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The normally air-free pleural cavity exists at subatmospheric pressure to promote pleural apposition and proper lung excursion. Owing to its unique bilayer structure, air introduced into this space either from within the thoracic cavity or from an extrathoracic source causes pleural separation and simple pneumothorax (PTX). Most simple pneumothoracies of a small or static volume in healthy patients do not appreciably impair cardiopulmonary function despite variable collapse of the lung. If increasing pressure develops within this pleural air collection, however, a cascade of pathophysiological changes can result from altered anatomical positions of heart, lung, and great vessels. The development of increasing pressure within the pleural space, with resultant ipsilateral lung collapse and hemithoracic expansion into the mediastinum and the contralateral lung, is termed tension pneumothorax (TPTX). The exact incidence of TPTX is unknown, but it is reported in up to 2 to 3% of all pneumothoracies. Certain medical and surgical disease states—many found within the critical care environment—place patients at higher risk for development of TPTX and also limit physiological tolerance to TPTX once it occurs. Although physical examination and chest radiography generally confirm the occurrence of TPTX, physiological monitoring may herald the development of increasing intrapleural pressure. Expeditious recognition and pleural decompression are necessary to prevent the untoward hemodynamic and respiratory consequences of TPTX. Significant morbidity and mortality may arise from TPTX if treatment is unduly delayed, particularly in mechanically ventilated patients.

Objective To determine the frequency of clinically important complications of femoral venous catheters. Design Prospective survey of major and minor complications. Setting A mixed medical/surgical ICU in a university hospital. Patients One hundred twenty-three patients admitted to the ICU who underwent femoral venous catheterization over a 2-yr period. Measurements and main results There were 150 catheters inserted in 123 patients for a mean duration of 6.4 days. There were no major complications including catheter-related sepsis. Minor complications consisted of arterial puncture (9.3%), local bleeding (10%), and local inflammation (4.7%). Critical care fellows had a significantly lower rate (6%) of insertion complications than interns or medical students (16%). We did not specifically look at the frequency of deep venous thrombosis. Conclusions Femoral venous catheterization offers an alternative site of insertion to the subclavian and jugular veins for central venous access in the critically ill. The occurrence rate of clinically important complications is acceptably low.

o Not Resuscitate (DNR) orders are established by competent patients or appropriate surro- gates to provide a mechanism for withholding specific resuscitative therapies in the event of a car- diopulmonary arrest. It is important for health care institutions to develop policies to deal with DNR or- ders in the setting of anesthesia and surgery as it is estimated that 15% of patients with DNR orders un- dergo a surgical procedure (1) and the frequency of DNR orders is increasing as the population becomes better informed about the Patient Self-Determination Act and advanced directives (2). Several surveys have documented confusion on the part of individual prac- titioners and have demonstrated that only a small percentage of institutions have specific policies re- garding perioperative DNR orders (3-6). This lack of consistency stems in part from the fact that surgery and anesthesia routinely involve physiologic stresses and suppression of vital signs far different from those experienced outside the operating room. The unique aspects of anesthesia create potential practical and ethical barriers to the implementation of perioperative DNR orders. In this paper, the complex medial and ethical issues surrounding the perioperative DNR or- ders are discussed, and the rationale for the recently introduced American Society of Anesthesiologists (ASA) guidelines is highlighted. Most of the surgery performed in patients with DNR orders is palliative and designed to improve patient comfort or simplify care. For many practitio- ners the definition of anesthesia includes routine sup- pression of respiration and performance of procedures such as endotracheal intubation and volume or drug infusion, which in other settings are often refused as

We used continuous positive airway pressure (CPAP) by face mask to treat 18 AIDS patients with Pneumocystis carinii pneumonia (PCP) who were in hypoxic respiratory failure. Candidates for mask CPAP were conscious, not hypercarbic, and able to protect their airway on ICU admission. Treatment was effective and well tolerated. Mean Po2 rose from 62 to 158 torr, respiratory rate decreased from 51 to 32 breath/min, and Pco2 was unchanged. Mean duration of treatment was 4.5 days. Only one patient developed a pneumothorax; there were no other major complications. Hospital mortality was 55%. CPAP by face mask allows speech and permits discussion of therapeutic limits. We present our protocol for using CPAP by face mask and conclude that CPAP is effective supportive therapy in hypoxic respiratory failure complicating PCP and AIDS.

We report a case of suspected carbon dioxide embolism occurring during laparoscopy. Among the sequelae was neurological dysfunction felt to be secondary to paradoxical embolization. The patient was treated with hyperbaric oxygen therapy. Hyperbaric oxygen should be considered when confronted with a clinically important gas embolism.