From the Guidelines
Microemboli in the lungs can cause significant morbidity and mortality, and immediate medical attention is required if suspected, with treatment typically involving anticoagulation therapy and supportive oxygen therapy as needed. The effects of microemboli on the lungs can be severe, with symptoms ranging from mild shortness of breath to severe respiratory distress depending on the number and size of emboli 1. Microemboli occur when fragments break off from larger clots elsewhere in the body or when fat, air, amniotic fluid, or tumor cells enter the circulation and travel to the lungs.
Causes and Risk Factors
The causes of microemboli include deep vein thrombosis, trauma, surgery, and medical conditions such as cancer or heart disease. Risk factors for microemboli include immobility, surgery, trauma, cancer, and genetic disorders that affect blood clotting.
Diagnosis and Treatment
Diagnosis of microemboli typically involves imaging tests such as CT scans or pulmonary angiography, as well as laboratory tests to detect blood clots. Treatment typically involves anticoagulation therapy, starting with intravenous heparin or low molecular weight heparin, followed by oral anticoagulants such as warfarin or direct oral anticoagulants like rivaroxaban 1. Supportive oxygen therapy may be needed depending on oxygen saturation levels.
Prevention Strategies
Prevention strategies include early mobilization after surgery, compression stockings, and prophylactic anticoagulation in high-risk patients. Long-term management may require 3-6 months of anticoagulation therapy, with duration determined by the underlying cause and risk factors. Thrombolysis may be indicated in patients who are hemodynamically unstable, particularly in the presence of hypotension 1.
Key Considerations
Key considerations in the management of microemboli include the need for immediate medical attention, the importance of anticoagulation therapy, and the need for supportive oxygen therapy as needed. The risk of recurrent microemboli and the risk of anticoagulant-related bleeding must also be carefully considered. Overall, the management of microemboli requires a comprehensive approach that takes into account the underlying cause, risk factors, and individual patient needs.
From the Research
Effects of Microemboli on the Lungs
- Microemboli can cause tissue ischemia, followed by inflammatory response and complement activation in the lungs 2
- The microbubble obstructs blood flow in the capillary, leading to further obstruction of microcirculation and tissue damage 2
- Pulmonary microembolism can be a cause of acute respiratory failure, with small fibrin degradation products contributing to pulmonary damage 3
- Microemboli containing fibrin and leukocytes may be involved as contributory agents in some cases of acute respiratory failure 3
Pathophysiology of Microemboli
- Microbubbles originate mainly in extracorporeal lines and devices, such as cardiopulmonary bypass and dialysis machines, but may be endogenous in cases of decompression sickness or mechanical heart valves 2
- Microbubbles lodge in the capillary bed of various organs, mainly the lungs, causing tissue damage and inflammatory response 2
- The degree of histological damage is related to the number and size of microemboli and the duration of pulmonary microcirculatory obstruction 4
Clinical Implications
- Microemboli can be detected and prevented, with management strategies including the use of membrane oxygenators instead of bubble oxygenators 4
- Quantitation of particulate microemboli during cardiopulmonary bypass can help identify causes of microemboli, such as infusion of banked blood stored for more than 3 days or use of cardiotomy reservoirs 4
- Pulmonary perfusion patterns can be used to diagnose tumor microembolism, with multiple small subsegmental peripheral defects and a "fissure sign" on perfusion lung scan 5