Diagnosis and management of acute hypoxemia after drainage of massive pericardial effusion

Diagnostic Bedside Ultrasonography for Acute Respiratory Failure and Severe Hypoxemia in the Medical Intensive Care Unit: Basics and Comprehensive Approaches

Bedside goal-directed ultrasound is a powerful tool for rapid differential diagnosis and monitoring of cardiopulmonary disease in the critically ill patient population. The bedside intensivist is in a unique position to integrate ultrasound findings with the overall clinical situation. Medically critically ill patients who require urgent bedside diagnostic assessment fall into 2 categories: (1) acute respiratory failure and (2) hemodynamic derangements. The first portion of this review outlines the diagnostic role of bedside ultrasound in the medically critically ill patient population for the diagnosis and treatment of acute respiratory failure, acute respiratory distress, and severe hypoxemia. The second portion will focus on the diagnostic role of ultrasound for the evaluation and treatment of shock states, as well as describe protocolized approaches for evaluation of shock during cardiopulmonary resuscitation. Different respiratory system pathologies that result in acute respiratory failure (such as increased interstitial fluid, alveolar consolidation, pleural effusion) cause characteristic ultrasonographic findings; diaphragmatic assessment may also add information. Intracardiac shunting can cause severe hypoxemia. Protocolized approaches for the evaluation of patients with acute respiratory failure or distress are discussed.

The intraoperative management of patients with pericardial tamponade

The anesthetic management of patients with pericardial tamponade is challenging, as they present with not only the cardiovascular compromise that defines pericardial tamponade, but often have comorbid conditions that increase the complexity of their management. This review describes the pathophysiology, etiology, clinical presentation, and anesthetic management of patients with pericardial tamponade, with an emphasis on the intraoperative period and the management of pericardial window procedures, the most common clinical scenario where anesthesiologists will encounter pericardial tamponade.

Prolonged right ventricular failure after relief of cardiac tamponade

PURPOSE

To report a case of severe and fatal cardiac complication following pericardiotomy to relieve a malignant tamponade. Right ventricular (RV) failure was responsible for major hypoxemia and for a persistent shunt through a patent foramen ovale. In the absence of pulmonary embolism and coronary occlusion, possible pathophysiologic mechanisms are discussed.

CLINICAL FEATURES

This 53-yr-old patient presented with oropharyngeal carcinoma previously treated by chemotherapy. One month later, he showed clinical and echocardiographic signs of cardiac tamponade. He had a circumferential pericardial effusion with complete end-diastolic collapse of the right cavities. After an emergent pericardiotomy, he rapidly presented severe hypoxemia. Transesophageal echocardiography showed an akinetic and dilated right ventricle, paradoxical septal wall motion and a normal left ventricular function. A contrast study revealed a right-to-left shunt. No residual pericardial effusion was detectable. Pulmonary angiography excluded a pulmonary embolism and the coronary angiogram was normal. Troponin Ic was elevated postoperatively and peaked on day two (3.78 micro g x L(-1)). The patient died of refractory shock with persistent intracardiac shunt and RV akinesia on day nine.

CONCLUSION

Although pulmonary embolism or thrombus of a coronary vessel are the most common causes of prolonged RV failure after pericardiotomy, other mechanisms may be invoked. The possibility is raised that a rapid increase in RV tension may induce the development of muscular injury and impair coronary blood flow, despite a normal coronary angiogram. These could result in a stunned myocardium and opening of a patent foramen ovale. We hypothesize that gradual decompression of a chronic pericardial effusion might be beneficial in patients at risk.

Presentation of non-Hodgkin's lymphoma as acute hypoxia caused by right ventricular compression

IMPLICATIONS

A case is presented of a woman developing acute right ventricular outflow tract obstruction because of mediastinal non-Hodgkin's lymphoma. Systemic blood flow was possible through a patent foramen ovale.

Pharmacologic exposure of an occult atrial septal defect

OBJECTIVE

To describe the diagnostic technique used to identify the presence of a symptomatic interatrial shunt obscured by normal intracardiac pressures and to discuss the unusual findings in this case and their relevance to the investigation of patients with unexplained hypoxemia.

DESIGN

Case report.

SETTING

Intensive care unit of a university teaching hospital.

PATIENT

A patient with a variant of the platypnea-orthodeoxia syndrome.

INTERVENTIONS

Intravenous administration of metaraminol.

MEASUREMENTS AND MAIN RESULTS

Clinical examination and routine investigations ruled out pneumonia or myocardial infarction as a cause of respiratory failure, and pulmonary angiography was normal other than for the demonstration of an interatrial communication. Repeated transthoracic echocardiograms failed to indicate the presence of a significant interatrial shunt that was eventually detected following temporary shunt reversal with intravenous metaraminol and confirmation by bubble-contrast transesophageal echocardiography and right heart catheter studies.

CONCLUSIONS

Symptomatic right-to-left intracardiac shunt may occur in patients with normal intracardiac and pulmonary artery pressures. The presence of a significant shunt cannot be ruled out by transthoracic echocardiography without the use of bubble contrast.