Pulmonary embolism. Modern concepts

Pulmonary embolism is a common disorder and an important cause of morbidity and mortality. Since genetic predisposition appears to explain only about one fifth of cases, identification of other risk factors is critical. Pulmonary embolism ranges from incidental, clinically unimportant thromboembolism to massive embolism with sudden death. The initial diagnostic approach in patients with suspected pulmonary embolism commonly involves transesophageal echocardiography and ventilation-perfusion scanning. In patients with indeterminate findings on these exams, thoracic spiral computed tomography, magnetic resonance imaging and magnetic resonance angiography have shown promise. Pulmonary angiography is becoming less used because it is invasive and expensive. Unfractioned heparin is considered the treatment of choice for most patients with pulmonary embolism, except those with hemodynamic instability, who may need thrombolytic therapy. There is limited information on the efficacy and safety of low-molecular-weight heparin for the initial treatment of symptomatic pulmonary embolism. An up to date review of the international literature focused in the epidemiology, pathophysiology, diagnosis, potential treatment and prognosis is presented.     

Pulmonary embolism

Pulmonary embolism (PE) is a common problem for which prompt diagnosis and treatment is essential to minimize mortality. The clinical presentation is more variable than sudden dyspnea and chest pain, especially in the critical care patient. Recognition of venous thromboembolic (VTE) risk factors can help develop a good clinical suspicion for PE. A wide range of diagnostic tests are available to the clinician. The ventilation/perfusion scan, pulmonary arteriogram, and lower extremity investigations are still important for diagnosis. Other noninvasive tests such as spiral CT with venography, echocardiography, and D-dimers are becoming more accepted. Heparin is the mainstay of PE therapy, but thrombolytic treatment may be lifesaving in the unstable patient. VTE prophylaxis should be considered in all post-operative or critical care patients.     

Pulmonary lymphangiectasia revisited

PURPOSE: Pulmonary lymphangiectasia (PL) is a rare, poorly documented disease characterized by abnormal pulmonary lymphatics. Although case reports are published, little is known about survivors past the neonatal period. METHODS: This is a retrospective review of histologically proven PL in fetuses, infants, and long term survivors since 1965. RESULTS: Eleven children (8 boys, 3 girls) and 8 aborted fetuses (7 male, 1 female) were identified. The fetuses weighed 463.4 g (177 to 681 g). Six were aborted between 19 to 24 weeks of gestation for multiple malformations or anencephaly, and 2 spontaneously aborted: one with PL only, the other with twin-twin transfusion syndrome. Clinical PL was diagnosed between 0 and 11 months of age. Six children died (2 neonatal, 4 within 10 days), 5 survived. Two deaths occurred after cardiac surgery. Among survivors, the symptomatology and frequency of admissions diminished over time. Symptoms included progressive respiratory distress, chronic cough, recurrent pneumonia, bronchial asthma, and choking. One child with bilateral chylothorax was later diagnosed with Noonan syndrome; 2 patients had minor cardiac malformations. Rapid deterioration occurred with mild respiratory infections with only supportive treatment available. Chest x-ray showed marked hyperinflation with interstitial infiltrate. CONCLUSIONS: This is the first long-term study of primary PL and will help counsel parents. Although fatal in the neonatal period, survival is possible if diagnosed past the neonatal period and improvement is expected.     

Pulmonary embolism during operation

A case of intra-operative pulmonary embolism is reported. Though this is evidently a rare occurrence, the diagnosis should be seriously considered when unexplained hypoxia occurs during operation. Appropriate investigation and treatment can then be initiated promptly.     

Pulmonary embolectomy for acute massive pulmonary embolism.

During the period from 1961 to 1981, 40 pulmonary embolectomies were performed in 39 patients who were in extremis at the time of initiation of cardiopulmonary bypass. In a 460-bed hospital with more than 17,000 acute admissions and 4,000 operations per year, this small number represents the few patients who are potentially salvageable by urgent embolectomy. Preoperative angiography was performed in 57% of the cases, and in another ten patients suspected of having pulmonary emboli, angiography prevented unnecessary thoracotomy. Despite their moribund condition, 43% of the embolectomy patients lived. Excluding two patients with tumor occlusion of the pulmonary arteries and three patients with chronic cor pulmonale from old pulmonary emboli, the survival rate was 50%. Ten patients died because of hypoxemia and hypotension prior to initiation of cardiopulmonary bypass, and seven died of myocardial depression of multiple etiologies. Portable cardiopulmonary bypass affords the possibility of survival in moribund patients with acute massive pulmonary embolism. Preoperative angiography is recommended to guide appropriate surgical management.     

Pulmonary embolism in the cardiac surgical patient.

Pulmonary embolism (PE) is thought to occur infrequently after cardiac operations, possibly because systemic heparinization during cardiopulmonary bypass prevents deep vein thrombosis. This retrospective study was undertaken to determine the actual incidence of PE after cardiac operations and to identify risk factors. Between January 1, 1985, and December 31, 1989, 5,694 adult patients (greater than 18 years old) had open heart operations at the Johns Hopkins Hospital. Thirty-two patients (20 men and 12 women) had PE within 60 days of operation, an overall PE incidence of 0.56%. The diagnosis of PE was established by ventilation/perfusion scan, pulmonary angiogram, or autopsy. Mortality among patients with PE was 34%. Using a case-control method, preoperative and postoperative risk factors for PE were identified by multivariate and multiple logistic regression analyses. Preoperative risk factors included bed rest (p less than 0.003), prolonged hospitalization before operation (p less than 0.004), and cardiac catheterization performed through the groin within 15 days before operation (p less than 0.01). Post-operative risk factors were congestive heart failure (p less than 0.008), prolonged bed rest (p less than 0.05), and deep vein thrombosis (p less than 0.03). This study demonstrates that PE is an unusual complication after cardiac operations, has a high mortality rate, and is often related to perioperative immobility and recent groin catheterization. These results also suggest that minimizing preoperative hospital stay may be important in PE prophylaxis.     

Pulmonary embolism following laparoscopic cholecystectomy

Laparoscopic abdominal surgery is considered a low-risk procedure for postoperative thromboembolic disease. We report two cases of pulmonary embolism following laparoscopic cholecystectomy, review the incidence of deep venous thrombosis and pulmonary embolism in laparoscopic cholecystectomy, and suggest a specific prophylactic scheme for patients undergoing laparoscopic cholecystectomy. In spite of the low incidence of postoperative thromboembolic disease following minimally invasive procedures, the risk of pulmonary embolism must not be underestimated and its symptoms must not be underdiagnosed.