DRG Category: 175
Mean LOS: 5.1 days
Description: Medical: Pulmonary Embolism With Major Complication or Comorbidity or Acute Cor Pulmonale
An embolism is any undissolved mass that travels in the circulation and occludes a blood vessel. A fat embolism, which is an unusual complication from a traumatic injury, occurs when fat droplets enter the circulation and lodge in small vessels and capillaries, particularly in the lung and brain. Two theories exist that explain the pathophysiology of fat emboli: the mechanical theory and the biochemical theory. The mechanical theory states that trauma disrupts fat cells and tears veins in the bone marrow at the site of a fracture. Fat droplets enter the circulation because of increased pressure of the interstitium at the area of injury. The biochemical theory states that a stress-related release of catecholamines after trauma mobilizes fat molecules from a tissue. These molecules group into fat droplets and eventually obstruct the circulation through an inflammatory response and the release of local toxic mediators. In addition, free fatty acids destroy pulmonary endothelium, increase capillary permeability in the lungs, and lead to pulmonary edema.
The result of either theory is the accumulation of fat droplets that are too large to pass easily through small capillaries, where they lodge and break apart into fatty acids, which are toxic to lung tissues, the capillary endothelium, and surfactant. Pulmonary hypertension, alveolar collapse, and even noncardiac pulmonary edema follow. If the patient has a patent foramen ovale (an opening in the wall between the right and left atria), the embolus may pass into the systemic circulation and affect the brain or kidneys. Mortality rates are approximately 10% to 20%. Patients with increased age, underlying medical conditions, and poor physiological reserves have poorer health outcomes than other patients.
Fat embolism is associated with severe traumatic injury with accompanying long-bone (tibial or femoral) or pelvic fractures and generally occurs within 3 days of the fracture. It has also been reported in patients with severe burns, head injury, or severely compromised circulation. Nontraumatic disease states that have occasionally been associated with fat embolism include acute pancreatitis, alcoholism, diabetes mellitus, sickle cell disease, and osteomyelitis. Procedures such as liposuction, orthopedic surgery, joint replacement, abdominal surgery, and cardiac massage (closed chest) are also associated with fat embolism. It is also associated with parenteral lipid infusion and corticoid administration. Fat embolisms are the most common nonthrombotic cause of pulmonary emboli.
Many patients who develop the disorder are under age 30 years and have severe associated traumatic injuries. Males are more likely than females to have a significant traumatic injury. Older adults have a poorer outcome than their younger counterparts.
Ethnicity, race, and sexual/gender minority status have no known effect on the risk for fat embolism.
While no global data are available, developed countries have a continuing problem with motor vehicle crashes leading to significant traumatic injuries. The surgeries that present risks for fat emboli are more common in developed countries than in developing countries. Traffic crashes are a growing problem in developing countries as more vehicles crowd roads that are not always well constructed. Around the world, fat emboli are common occurrences following trauma.
ASSESSMENT
History
Elicit a history of recent traumatic injury, particularly blunt trauma leading to long-bone or pelvic fractures. In most patients, the injury is obvious because of the presence of wounds, fractures, casts, or traction devices. Some patients exhibit changes in mental status such as restlessness, delirium, or drowsiness progressing to coma and even seizures. Others complain of fever, anxiety, unexplained discomfort, or respiratory distress (shortness of breath, cough).
Fat embolization may be classified into three distinct forms based on the patient's progression of symptoms: subclinical, classic, and fulminant. Approximately half of patients with uncomplicated fractures have subclinical fat emboli, which resolve spontaneously within a few days. Patients with the classic form generally have a latent period of 1 to 2 days, followed by the development of symptoms that include mental status changes, shortness of breath, fever, tachycardia, and petechiae. The fulminant form is characterized by an early onset of neurological and respiratory deterioration as well as the onset of signs of right ventricular failure (distended neck veins, liver congestion, peripheral edema). A rapid onset of neurological deterioration in patients who sustained severe injuries and multiple fractures but who were initially conscious suggests a fat embolism.
The most common symptoms are related to cardiopulmonary function and include tachycardia, dyspnea, fever, and signs of hypoxemia, including restlessness, agitation, confusion, or even stupor. Some patients may have a seizure. Note that neurological changes usually occur 6 to 12 hours before respiratory system changes and rarely without impending respiratory involvement.
Inspect the patient's skin for petechiae, a classic sign that appears 1 to 2 days after injury in more than half of patients with fat embolism. Petechiae are of short duration, last only 4 to 6 hours, and appear most commonly on the neck, upper trunk, conjunctivae, or retina. An ophthalmic examination may reveal fat globules in the retinal vessels. Approximately half of the patients who display neurological symptoms also develop microinfarcts of the retina. When auscultating the patient's heart and lungs, a rapid heart rate and respiratory rate with rales, rhonchi, and possibly a pleural friction rub are usually heard.
Psychosocial
Because fat embolism is a complication of other disease processes or traumatic injuries, the addition of another life-threatening complication could be the final breaking point for the family or significant others involved. Evaluate the patient's social network to determine what support is available during the acute illness.
Test | Normal Result | Abnormality With Condition | Explanation |
---|---|---|---|
Platelet count | 150,000–450,000/mm3 | Decreased < 15,000 mm3 | Platelets are used up in the clotting process |
Pao2 | 80–95 mm Hg | <60 mm Hg | Hypoxemia occurs because of problems with ventilation and perfusion due to obstruction of pulmonary circulation |
Electrocardiogram | Normal rate; rhythm; and P, Q, R, S, and T waves | Tachycardia, right bundle branch block, depressed ST segments | Obstruction of the pulmonary circulation leads to right heart strain |
Other Tests: Increased serum lipase, fat in the urine, fibrinogen, complete blood count, patchy infiltrates on chest x-ray, ventilation perfusion scans, computed tomography and magnetic resonance imaging, pulse oximetry to detect arterial oxygen saturation, transesophageal echocardiography, calcium levels, arterial blood gas analysis
Diagnosis
DiagnosisImpaired gas exchange related to pulmonary capillary inflammation and arteriovenous shunting as evidenced by dyspnea, restlessness, and/or agitation
Outcomes
OutcomesRespiratory status: Gas exchange; Respiratory status: Ventilation; Symptom control; Symptom severity; Comfort level
PLANNING AND IMPLEMENTATION
Support for Airway, Breathing, and Circulation
Management of the patient with severe symptoms of fat emboli almost always requires support of the patient's airway and breathing with supplemental oxygen, airway pressure release ventilation, and possibly endotracheal intubation and mechanical ventilation. Patients with a deteriorating mental status, dropping arterial oxygen saturations, and decreasing levels of Pao2 (less than 50 mm Hg) may need positive pressure ventilation with positive end-expiratory pressure and possibly pressure control ventilation. Serial monitoring with pulse oximetry is important. Tachycardia may resolve with treatment of hypoxemia, but if hypotension and circulatory depression occur, fluid resuscitation, blood transfusion, and vasoactive medications may be required. However, volume overload may worsen hypoxemia, so volume is administered judiciously, and pulmonary artery catheterization may be necessary.
The nurse and trauma surgeon or orthopedist work together to prevent fat emboli whenever possible by encouraging adequate gas exchange; this entails clearing secretions and promoting good ventilation. Discuss the patient's activity restrictions with the physician. To limit the effects of immobilization, turn the patient frequently and, when the patient is ready, get the patient out of bed. If the injuries allow, encourage dangling or ambulation. Maintain the patient's hydration by IV or enteral fluids, as prescribed, and provide prophylaxis for deep venous thrombosis and stress-related gastrointestinal bleeding. Hematological laboratory measures are followed carefully to determine the need for blood component therapy.
Pharmacologic
Diuretics may be needed if pulmonary edema develops. Many experts recommend prophylactic use of corticosteroids, particularly methylprednisolone, for patients at high risk for fat emboli, but they seem less effective after fat emboli develop. Some experts suggest that the introduction of steroids may help treat pulmonary manifestations by decreasing the inflammatory response of the pulmonary capillaries as well as by stabilizing lysosomal and capillary membranes; corticosteroid use is not supported by randomized controlled trials. Analgesics are also necessary to manage the pain of the traumatic injury.
The best treatment of fat emboli is preventing their occurrence. Surgical stabilization of extremity fractures to reduce bone movement probably minimizes the release of fatty products from the bone marrow. The location of the fracture determines whether the surgeon uses internal or external fixation techniques.
Pharmacologic Highlights
General Comments: Medications provide supportive management rather than curative measures.
Medication or Drug Class | Dosage | Description | Rationale |
---|---|---|---|
Corticosteroids, often methylprednisolone | Varies with drug | Anti-inflammatories | Decrease inflammatory response of pulmonary capillaries; stabilize lysosomal and capillary membranes; use is controversial |
Other Drugs: Analgesics are also necessary to manage the pain of the traumatic injury.
The highest priority is maintaining the airway and breathing to reduce the effects of hypoxemia. Ongoing monitoring of the pulmonary system is essential, coupled with interventions such as suctioning and placement of an oral airway. Serial assessments of the heart rate and blood pressure are important to ongoing assessment of the circulatory system. If the cardiopulmonary system becomes compromised (ongoing hypoxemia, unresolved tachycardia, persistent hypotension), further consultation with the trauma service is essential.
Patients need to be active participants in their care. Before they undergo activity or coughing and deep-breathing exercises, make sure that the patient's pain is controlled. In addition to administering prescribed medications, explore nonpharmacologic alternatives to pain management, such as diversionary activities and guided imagery.
The patient's and family's level of anxiety is apt to be exacerbated by the critical care environment. Explain all the equipment and answer questions honestly and thoroughly. If the patient has to undergo endotracheal intubation, provide a method for communication, such as a magic slate or point board. Work with the family to allow as much visitation as the patient's condition allows. Remember that although young people in their late teens often appear to be adults, they often regress during a serious illness and need a great deal of support from their parents and significant others.
Evidence-Based Practice and Health Policy
Tsitsikas, D., Bristowe, J., & Abukar, J. (2020). Fat embolism syndrome in sickle cell disease. Journal of Clinical Medicine, 9, 3601–3616.
A patient who has recovered from the underlying disease process or injury is no longer at risk for developing fat embolism and can be discharged. Teach the patient about any medications and treatments needed before the patient leaves the hospital. Explain the disease process and how it occurred, and note that recurrence is doubtful unless the patient experiences another traumatic injury. Arrange for any follow-up care with the primary healthcare provider.