Nonthrombotic Embolism

Cholesterol Embolism

Overview

• Also known as atheroembolism or cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystal embolism
• Occurs when cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystals within an atherosclerotic plaque Plaque Primary Skin Lesions dislodge and embolize
• Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystals tend to:
  • Dislodge from proximal, large-caliber arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology 
  • Move to many more distal, small-to-medium arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology → simultaneous damage to multiple end-organs

Epidemiology and etiology

• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: unknown (many unrecognized cases)
• Typical patient characteristics:
  • Age: > 50 years
  • Gender Gender Gender Dysphoria: higher prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency in men than in women
  • Medical history: atherosclerotic disease
• Etiology:
  • Iatrogenic Iatrogenic Any adverse condition in a patient occurring as the result of treatment by a physician, surgeon, or other health professional, especially infections acquired by a patient during the course of treatment. Anterior Cord Syndrome following an invasive vascular procedure (75%):
    • Angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery
    • Cardiac catheterization Cardiac Catheterization Procedures in which placement of cardiac catheters is performed for therapeutic or diagnostic procedures. Cardiac Surgery
    • Endovascular grafting
  • Spontaneous (25%)
• Risk factors (similar to those associated with atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis):
  • Hypercholesterolemia Hypercholesterolemia A condition with abnormally high levels of cholesterol in the blood. It is defined as a cholesterol value exceeding the 95th percentile for the population. Lipid Disorders
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus 
  • Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity 
  • Smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases
  • Abdominal aortic aneurysms
• Worse atherosclerotic disease → higher risk for cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism embolization Embolization A method of hemostasis utilizing various agents such as gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and intracranial arteriovenous malformations, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage. Gastrointestinal Bleeding

Pathophysiology

• Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystals within a ruptured atherosclerotic plaque Plaque Primary Skin Lesions embolize → “showering” of debris into the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment → multiple emboli → lodge in arterioles Arterioles The smallest divisions of the arteries located between the muscular arteries and the capillaries. Arteries: Histology
• Results in multiple occlusions that affect multiple organs

Clinical presentation

The classic presentation includes skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions findings, abdominal pain Abdominal Pain Acute Abdomen, and progressive renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome following a vascular procedure. Neurological and ocular symptoms are also common if the emboli travel superiorly.

• Symptoms vary and depend on several factors:
  • Location of the embolic source:
    • The aortic arch Aortic arch Mediastinum and Great Vessels: Anatomy may embolize to the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, eye, or upper extremity.
    • Thoracic aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy or abdominal aorta Abdominal Aorta The aorta from the diaphragm to the bifurcation into the right and left common iliac arteries. Posterior Abdominal Wall: Anatomy may embolize to the GI tract or lower extremities.
  • Extent of embolization Embolization A method of hemostasis utilizing various agents such as gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and intracranial arteriovenous malformations, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage. Gastrointestinal Bleeding
  • Partial versus complete occlusion of the affected vessels 
  • Presence or absence of pre-existing vascular disease in the affected area
• Common dermatological presentations:
  • Cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination 
  • Ulcers 
  • Purpura 
  • Petechiae Petechiae Primary Skin Lesions
  • Firm, painful erythematous nodules Erythematous Nodules Hidradenitis Suppurativa
  • Livedo reticularis Livedo reticularis A condition characterized by a reticular or fishnet pattern on the skin of lower extremities and other parts of the body. This red and blue pattern is due to deoxygenated blood in unstable dermal blood vessels. The condition is intensified by cold exposure and relieved by rewarming. Chronic Kidney Disease: lace-like purplish discoloration of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions that blanches with pressure
  • Blue-toe syndrome: a retiform purpura Retiform Purpura Disseminated Intravascular Coagulation, blue discoloration of the toes 
• Renal presentations:
  • AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury:
    • Most commonly causes distal parenchymal ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage
    • Irregularly shaped emboli produce incomplete occlusion → secondary ischemic atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation 
    • Progressive renal dysfunction
    • Occurs weeks after a possible inciting event
    • Bland sediment
    • Flank pain Flank pain Pain emanating from below the ribs and above the ilium. Renal Cell Carcinoma and hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma are uncommon with cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism emboli (but common with thromboemboli that cause acute renal infarction Renal Infarction Imaging of the Urinary System)
  • Rhabdomyolysis Rhabdomyolysis Rhabdomyolysis is characterized by muscle necrosis and the release of toxic intracellular contents, especially myoglobin, into the circulation. Rhabdomyolysis:
    • Red-brown urine (due to myoglobinuria Myoglobinuria The presence of myoglobin in urine usually as a result of rhabdomyolysis. Rhabdomyolysis)
    • Electrolyte abnormalities
    • ↑ CK
• GI presentations:
  • General symptoms:
    • Abdominal pain Abdominal Pain Acute Abdomen
    • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
    • GI bleeding
  • GI ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage
  • Acute pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis
  • Hepatic cell necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage
  • Necrotizing cholecystitis Cholecystitis Cholecystitis is the inflammation of the gallbladder (GB) usually caused by the obstruction of the cystic duct (acute cholecystitis). Mechanical irritation by gallstones can also produce chronic GB inflammation. Cholecystitis is one of the most common complications of cholelithiasis but inflammation without gallstones can occur in a minority of patients. Cholecystitis
• Neurological presentations:
  • General symptoms:
    • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
    • Dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome)
    • Paralysis
    • Confusion
  • Transient ischemic attack Transient ischemic attack Transient ischemic attack (TIA) is a temporary episode of neurologic dysfunction caused by ischemia without infarction that resolves completely when blood supply is restored. Transient ischemic attack is a neurologic emergency that warrants urgent medical attention. Transient Ischemic Attack (TIA) 
  • Stroke 
• Ocular presentations:
  • Amaurosis fugax Amaurosis fugax Transient complete or partial monocular blindness due to retinal ischemia. This may be caused by emboli from the carotid artery (usually in association with carotid stenosis) and other locations that enter the central retinal artery. Carotid Artery Stenosis: temporary acute loss of vision Vision Ophthalmic Exam due to a lack of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure to the eye
  • Hollenhorst plaque Plaque Primary Skin Lesions on ophthalmoscopy: bright, refractile lesions in the retina Retina The ten-layered nervous tissue membrane of the eye. It is continuous with the optic nerve and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the choroid and the inner surface with the vitreous body. The outermost layer is pigmented, whereas the inner nine layers are transparent. Eye: Anatomy indicative of cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystal embolization Embolization A method of hemostasis utilizing various agents such as gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and intracranial arteriovenous malformations, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage. Gastrointestinal Bleeding from a proximal source (e.g., carotid artery)
  • Eye pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Blurred vision Blurred Vision Retinal Detachment

Diagnosis

The diagnosis is usually clinical. Definitive diagnosis requires a biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma.

• Laboratory testing: generally nonspecific
  • CBC: ↑ eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation, ↓ RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology, ↓ platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology 
  • Inflammatory markers: ↑ CRP, ↑ ESR ESR Soft Tissue Abscess
  • Organ-specific tests may be abnormal if the organ is affected:
    • ↑ Creatinine/BUN ( kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy)
    • ↑ Amylase Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Digestion and Absorption ( pancreas Pancreas The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. This organ has both exocrine and endocrine tissue. Pancreas: Anatomy)
    • ↑ Transaminases Transaminases A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. Autoimmune Hepatitis ( liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy)
• Imaging:
  • Useful in assessing the extent of atherosclerotic disease
  • Rarely useful in identifying the index plaque Plaque Primary Skin Lesions
  • Identification Identification Defense Mechanisms of multiple complex plaques or multiple ischemic strokes assists in presumptive diagnosis.
  • Modalities:
    • Transesophageal echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA) ( TEE TEE Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues using a transducer placed in the esophagus. Imaging of the Heart and Great Vessels): 1st-line approach for thoracic aortic sources
    • Chest CT
    • Chest MRI
    • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification imaging (may reveal multiple small ischemic lesions)
• Histopathology:
  • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma sample can be obtained from any affected organs (e.g., skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, kidney, muscle).
  • Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism clefts (“ghosts”) within the arterioles Arterioles The smallest divisions of the arteries located between the muscular arteries and the capillaries. Arteries: Histology:
    • Cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystals are dissolved during tissue fixation leaving behind clefts.
    • Crescent-shaped clefts with pointed ends
    • Elongated ovoid spaces

Management

• Supportive management for presenting symptoms:
  • Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways management
  • Avoid further vascular instrumentation if possible.
  • Anti-thrombotic therapy is controversial and generally not recommended.
• Prevention of kidney injury:
  • Aggressive saline hydration
  • Bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes
  • Mannitol Mannitol A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity. Osmotic Diuretics
  • Dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Peritoneal Dialysis and Hemodialysis may be needed if the injury is significant.
• Surgical plaque Plaque Primary Skin Lesions removal or exclusion (if the embolic source is clearly identified)
• Risk-factor reduction to prevent recurrent disease:
  • Aspirin Aspirin The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. Nonsteroidal Antiinflammatory Drugs (NSAIDs)
  • Statins Statins Statins are competitive inhibitors of HMG-CoA reductase in the liver. HMG-CoA reductase is the rate-limiting step in cholesterol synthesis. Inhibition results in lowered intrahepatocytic cholesterol formation, resulting in up-regulation of LDL receptors and, ultimately, lowering levels of serum LDL and triglycerides. Statins
  • BP control
  • Smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases cessation
  • Glycemic control

Fat Embolism

Overview

• Occurs when fat globules enter the pulmonary or systemic circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment 
• Most common in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with orthopedic trauma, especially:
  • Multiple fractures
  • Open (instead of closed) fractures
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency:
  • 20%–30% in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship after trauma
  • 1%–11% in long-bone fractures
  •  Occurs in 90% of individuals with severe skeletal injuries, but < 10% show any clinical findings
• Gender Gender Gender Dysphoria bias Bias Epidemiological studies are designed to evaluate a hypothesized relationship between an exposure and an outcome; however, the existence and/or magnitude of these relationships may be erroneously affected by the design and execution of the study itself or by conscious or unconscious errors perpetrated by the investigators or the subjects. These systematic errors are called biases. Types of Biases: men > women
• Age: most common in individuals between 10 and 40 years of age

Etiology

• Traumatic causes:
  • Orthopedic causes (vast majority of cases):
    • Long-bone fractures
    • Pelvic fractures Pelvic Fractures Pelvic fractures are a disruption in the cortex of a pelvic bone involving iliac wing fractures, acetabular fractures, or those causing loss of integrity of the pelvic ring (the sacrum and the 2 innominate bones). Patients often present with a history of trauma or a fall, limb length discrepancy, intense pain on palpation, and mechanical instability. Pelvic Fractures
    • Fractures of other marrow-containing bones (e.g., ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy)
  • Non-orthopedic causes (rare):
    • Cardiopulmonary resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome
    • Severe burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns
    • Crush injuries
    • Liposuction 
    • Bone marrow transplant Bone marrow transplant Transfer of hematopoietic stem cells from bone marrow or blood between individuals within the same species (homologous transplantation) or transfer within the same individual (autologous transplantation). Hematopoietic stem cell transplantation has been used as an alternative to bone marrow transplantation in the treatment of a variety of neoplasms. Organ Transplantation
• Nontraumatic causes (very rare):
  • Acute pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis 
  • Sickle-cell hemoglobinopathies Hemoglobinopathies A group of inherited disorders characterized by structural alterations within the hemoglobin molecule. Anemia: Overview and Types
  • Lipid infusion
  • Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage

Pathogenesis

Pathogenesis may be by 1 or both of the following mechanisms:

• Fat globules cause mechanical obstruction Mechanical Obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Imaging of the Intestines in the vasculature.
• Embolized fat may degrade into toxic intermediaries → leads to inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and endothelial injury

Clinical presentation

Signs and symptoms typically develop 24–72 hours after the inciting event.

• Classic triad of symptoms after trauma:
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
  • Neurological abnormalities
  • Petechial rash Rash Rocky Mountain Spotted Fever
• Cardiopulmonary symptoms:
  • Sudden onset tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination
  • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome 
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children
• Neurological symptoms:
  • Changes in mental status
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
• Dermatological symptoms: diffuse petechial rash Rash Rocky Mountain Spotted Fever
• Hematological signs:
  • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
  • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia

Diagnosis and management

Fat embolism is usually a clinical diagnosis after excluding other possibilities.

• Imaging:
  • Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests and/or CT in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with respiratory symptoms
  • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification CT or MRI in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with neurological symptoms
• Management:
  • No definitive treatment
  • Supportive care during natural resolution:
    • Ensure hemodynamic stability
    • Oxygenation and ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing as needed
    • Adequate nutrition and hydration
    • Prophylaxis Prophylaxis Cephalosporins for deep vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus ( DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis)
  • Early reduction and fixation of long-bone fractures

Air Embolism

Overview

An air embolism occurs when gas bubbles enter the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment and block blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure.

• 2 types:
  • Venous air embolism
  • Arterial air embolism
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: unknown

Pathophysiology and etiology

• Air embolisms occur when:
  • There is direct communication Communication The exchange or transmission of ideas, attitudes, or beliefs between individuals or groups. Decision-making Capacity and Legal Competence between air and the vasculature, AND pressure gradient Pressure gradient Vascular Resistance, Flow, and Mean Arterial Pressure favors air movement into the vessel (instead of bleeding, which would result in blood moving out of the vessel) 
  • Example: Procedures involving surgical incision Surgical Incision Surgical Site Infections above the heart create negative venous pressure with respect to the atmospheric pressure Atmospheric pressure The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned. Ventilation: Mechanics of Breathing.
• Venous air embolism: 
  • Obstruction occurs when the volume of air in a vessel exceeds the ability of the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy to remove gas (approximately 50 mL).
  • Large bubbles obstruct the pulmonary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology → ↓ blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure to lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy:
    • ↑ Central venous pressure Central venous pressure The blood pressure in the central large veins of the body. It is distinguished from peripheral venous pressure which occurs in an extremity. Central Venous Catheter
    • ↓ Pulmonary arterial pressure Pulmonary Arterial Pressure Pulmonary Hypertension Drugs
    • ↓ Systemic arterial pressure
  • Small bubbles obstruct the pulmonary arterioles Arterioles The smallest divisions of the arteries located between the muscular arteries and the capillaries. Arteries: Histology and microcirculation:
    • ↑ Pulmonary vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing
    • ↑ Pulmonary arterial pressure Pulmonary Arterial Pressure Pulmonary Hypertension Drugs
    • ↑ Right ventricular pressure
    • Local inflammation Local Inflammation Surgical Site Infections and endothelial damage → noncardiogenic pulmonary edema Noncardiogenic Pulmonary Edema Pulmonary Edema, bronchoconstriction, and hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage
  • Very small bubbles may pass through the capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology into arterial circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment.
  • Fatal volume: estimated range between 50 and 500 mL in venous circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment at a rate of 100 mL/sec
• Arterial air embolism:
  • Air occludes microcirculation → end-organ ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage
  • Ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage induces inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation → endothelial damage
  • Fatal volumes:
    • 2 mL in cerebral arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology
    • 0.5–1 mL in coronary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology

Clinical presentation

Presentation depends on the site and size of the embolism.

Venous air embolism → air travels to the right ventricle → pulmonary circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment:

• Mimics a thrombotic pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism (PE)
• Symptoms:
  • Sudden-onset dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children 
  • Decreased oxygen saturation Oxygen Saturation Basic Procedures
  • Lightheaded/ dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome)

Arterial air embolism → air travels to end organs → ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage:

• Most commonly affected organs:
  • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification → stroke
  • Heart → MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction
• Symptoms:
  • Sudden onset of focal neurological deficits Focal Neurological Deficits Brain Abscess (e.g., hemiparesis Hemiparesis The term hemiparesis refers to mild to moderate weakness involving one side of the body. Epidural Hemorrhage)
  • Changes in mental status
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
  • Chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways/ dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea

Diagnosis

Diagnosis is made by determining air in the intravascular space or organs of a patient with known risk factors. However, air is often rapidly reabsorbed and no longer present by the time the patient undergoes diagnostic testing; thus, the diagnosis is often made clinically.

• Imaging:
  • CT:
    • Head (most helpful): intraparenchymal gas, diffuse edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, areas of infarction
    • Chest: may demonstrate air in the cardiac chambers or large vessels
  • Transthoracic echocardiography Transthoracic Echocardiography Imaging of the Heart and Great Vessels: may reveal air in the cardiac chambers or large veins Large veins Veins: Histology
• ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG): 
  • Venous embolism: right heart strain (peaked T waves, right bundle branch block Right bundle branch block Bundle Branch and Fascicular Blocks, right axis deviation)
  • Arterial embolism: ST depression or elevation
• Arterial blood gas Arterial blood gas Respiratory Alkalosis:
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
  • Hypercarbia
  • Metabolic acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis

Management

Stabilize the patient:

• Airway Airway ABCDE Assessment: Secure the airway Airway ABCDE Assessment (intubate), if needed.
• Breathing
  • High flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure of oxygen
  • Mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing if needed
• Circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  • IV access 
  • Volume resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome
  • Vasopressors Vasopressors Sepsis in Children
  • Advanced cardiac life support if needed

Repositioning:

• Venous embolism:
  • Left lateral decubitus position with head down
  • Keeps air in the right ventricle and away from the pulmonary outflow tract
• Arterial embolism:
  • Supine position
  • Arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology are strong enough to overcome positioning; the supine position attempts to minimize cerebral edema Cerebral edema Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries. An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive hydrocephalus). Increased Intracranial Pressure (ICP) caused by a cerebral air embolism.

Definitive therapies:

• Hyperbaric oxygen Hyperbaric oxygen The therapeutic intermittent administration of oxygen in a chamber at greater than sea-level atmospheric pressures (three atmospheres). It is considered effective treatment for air and gas embolisms, smoke inhalation, acute carbon monoxide poisoning, caisson disease, clostridial gangrene, etc. The list of treatment modalities includes stroke. Decompression Sickness:
  • ↑↑ Levels of blood oxygen create a large gradient for nitrogen Nitrogen An element with the atomic symbol n, atomic number 7, and atomic weight [14. 00643; 14. 00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth’s atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells. Urea Cycle to move from the air bubbles into the blood → ↓ the size of the bubbles 
  • ↑ Oxygen helps treat tissue ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage (secondary benefit)
• Removal of embolized air (e.g., aspiration through a catheter)
• Chest compression Chest Compression Crush Syndrome:
  • Forces air into smaller vessels
  • Used as a last resort in unstable patients Unstable Patients Blunt Chest Trauma

Amniotic Fluid Embolism

Overview

Amniotic fluid embolism Amniotic Fluid Embolism Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth ( AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth) is a complication during labor and the immediate postpartum period Postpartum period In females, the period that is shortly after giving birth (parturition). Postpartum Complications.

• Caused by the entry of the amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity into the maternal circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment by:
  • Placental tears
  • Uterine vein rupture
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: 1:40,000 deliveries
• Mortality Mortality All deaths reported in a given population. Measures of Health Status:
  •  80% mortality Mortality All deaths reported in a given population. Measures of Health Status rate due to AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth 
  • AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth causes 10% of maternal deaths in developed countries.

Risk factors

• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery
• Instrumented vaginal delivery (e.g., forceps Forceps Surgical Instruments and Sutures or vacuum-assisted deliveries)
• Placental abnormalities Placental abnormalities Normal placental structure and function are essential for a healthy pregnancy. Some of the most common placental abnormalities include structural anomalies (such as a succenturiate lobe or velamentous cord insertion), implantation anomalies (such as placenta accreta and placenta previa), and functional anomalies (such as placental insufficiency). Placental Abnormalities (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities)
• Preeclampsia Preeclampsia A complication of pregnancy, characterized by a complex of symptoms including maternal hypertension and proteinuria with or without pathological edema. Symptoms may range between mild and severe. Pre-eclampsia usually occurs after the 20th week of gestation, but may develop before this time in the presence of trophoblastic disease. Hypertensive Pregnancy Disorders/ eclampsia Eclampsia Onset of hyperreflexia; seizures; or coma in a previously diagnosed pre-eclamptic patient (pre-eclampsia). Hypertensive Pregnancy Disorders

Pathogenesis

• Unclear
• Amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity enters maternal circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment and triggers:
  • Intense pulmonary vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure:
    • ↑ Pulmonary pressure → right ventricular failure → systemic hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
    • Hypoxemic respiratory failure Hypoxemic Respiratory Failure Respiratory Failure
    • Pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema
  • Abnormal immune responses are activated:
    • Intense inflammatory response (similar to SIRS)
    • Inflammatory mediators activate the coagulation cascade Coagulation cascade The coagulation cascade is a series of reactions that ultimately generates a strong, cross-linked fibrin clot. Hemostasis systemically → disseminated intravascular coagulation Disseminated intravascular coagulation Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation ( DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation) 
• DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation leads to:
  • Hemorrhage → further hemodynamic instability
  • Ischemic multi-organ failure
• Mechanical obstruction Mechanical Obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Imaging of the Intestines from the amniotic-fluid debris likely does not play a significant role.

Clinical presentation

AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth typically presents dramatically, as sudden-onset cardiopulmonary collapse occurring during labor or within 30 minutes after delivery.

• Signs:
  • Cardiopulmonary collapse: loss of breathing and pulse
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome/ cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination
  • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children 
• Other symptoms:
  • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
  • Changes in mental status
  • Seizure 
• DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation:
  • Usually develops shortly after an AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth
  • Leads to obstetric hemorrhage
• Fetal heart-rate abnormalities indicating distress (e.g., late decelerations, terminal bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias) if still pregnant

Diagnosis

AFE AFE Blocking of maternal circulation by amniotic fluid that is forced into uterine veins by strong uterine contraction near the end of pregnancy. It is characterized by the sudden onset of severe respiratory distress and hypotension that can lead to maternal death. Complications during Childbirth is a clinical diagnosis based on presentation. 

• Laboratory evaluation (primarily to help with resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome):
  • Coagulation profile:
    • ↑ Prothrombin time Prothrombin time Clotting time of plasma recalcified in the presence of excess tissue thromboplastin. Factors measured are fibrinogen; prothrombin; factor V; factor VII; and factor X. Hemostasis
    • ↓ Fibrinogen Fibrinogen Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides a and b, the proteolytic action of other enzymes yields different fibrinogen degradation products. Hemostasis
    • ↑ D-dimer D-dimer Deep Vein Thrombosis
  • CBC:
    • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types 
    • Leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus
    • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia 
  • Arterial blood gas Arterial blood gas Respiratory Alkalosis:
    • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
    • Acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis (both respiratory and metabolic)
• Imaging (once the patient is stable):
  • Chest radiography: bilateral diffuse infiltrates
  • Echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA) to assess cardiac function

Management

Survival depends on prompt diagnosis and effective resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome.

• Airway Airway ABCDE Assessment: Secure the airway Airway ABCDE Assessment.
• Breathing: mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing
• Circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment:
  • High-quality CPR CPR The artificial substitution of heart and lung action as indicated for heart arrest resulting from electric shock, drowning, respiratory arrest, or other causes. The two major components of cardiopulmonary resuscitation are artificial ventilation and closed-chest cardiac massage. Cardiac Arrest
  • 2 large-bore IVs → fluid resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome
  • Transfuse to combat DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation; typically a 1:1:1 ratio of:
    • Packed RBCs Packed RBCs Transfusion Products
    • Fresh frozen plasma Fresh Frozen Plasma Transfusion Products
    • Cryoprecipitate Cryoprecipitate Transfusion Products
  • Vasopressors Vasopressors Sepsis in Children
• Immediate delivery if the patient is still pregnant

Complications

• Hematological: DIC DIC Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade. This cascade results in both widespread microvascular thrombi contributing to multiple organ dysfunction and consumption of clotting factors and platelets, leading to hemorrhage. Disseminated Intravascular Coagulation
• Cardiovascular: hemorrhage and cardiac arrest Cardiac arrest Cardiac arrest is the sudden, complete cessation of cardiac output with hemodynamic collapse. Patients present as pulseless, unresponsive, and apneic. Rhythms associated with cardiac arrest are ventricular fibrillation/tachycardia, asystole, or pulseless electrical activity. Cardiac Arrest
• Pulmonary complications: pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema and ARDS
• Permanent neurological deficits due to cerebral hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage (85% of survivors)

Tumor and Foreign-body Embolism

Tumor Tumor Inflammation embolism

• Embolization Embolization A method of hemostasis utilizing various agents such as gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and intracranial arteriovenous malformations, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage. Gastrointestinal Bleeding of tumor Tumor Inflammation within the pulmonary vessels
• Rare, end-stage manifestation of malignancy Malignancy Hemothorax
• Can occur with any malignancy Malignancy Hemothorax, though most commonly associated with:
  • Renal-cell carcinoma
  • Hepatocellular carcinoma Hepatocellular carcinoma Hepatocellular carcinoma (HCC) typically arises in a chronically diseased or cirrhotic liver and is the most common primary liver cancer. Diagnosis may include ultrasound, CT, MRI, biopsy (if inconclusive imaging), and/or biomarkers. Hepatocellular Carcinoma (HCC) and Liver Metastases
  • Adenocarcinomas:
    • Breast
    • Stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach: Anatomy
    • Colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy
    • Lung
• Clinical presentation:
  • Subacute progressive dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Cough, with or without hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis
  • May present with signs of venous thromboembolism Thromboembolism Obstruction of a blood vessel (embolism) by a blood clot (thrombus) in the blood stream. Systemic Lupus Erythematosus ( dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage, right heart strain)
• Diagnosis is often made on autopsy:
  • Imaging studies are insensitive.
  • Lab studies are nonspecific.
• Poor prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

Foreign-body embolism

• Most commonly involves silicone and occurs after cosmetic or therapeutic injection
• Clinical presentation:
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Petechial rash Rash Rocky Mountain Spotted Fever
  • Neurological symptoms
• Management is supportive.

Summary