Showing papers by "Warren M. Zapol published in 1978"

Membrane lung therapy of acute respiratory failure.

Abstract: Intensive care physicians treating patients with severe acute respiratory failure have followed over the past ten years the stepwise development and clinical testing of membrane artificial lungs. Perfusion with these devices was predicated on the premise that by maintaining for several days the body's normal arterial oxygen and carbondioxide tensions we would enable acutely injured lung to heal and the patient to survive. In order to test this hypothesis, a randomised study was performed in patients with severe acute hypoxemia contrasting conventional mechanical ventilation with such ventilation supplemented by venoarterial membrane lung partial perfusion [ 1 ]. Ninety adult patients were treated over two and one-half years by nine centres in a US National Heart and Lung Institute collaborative study; forty-two patients were treated with venoarterial bypass plus mechanical ventilation, forty-eight by mechanical ventilation alone. The study showed no difference in the probability of survival with either therapy: four patients survived in each group; most died with near total pulmonary failure [2]. For the 66% of the study patients suffering from bacterial and viral pnuemonia bypass provided no advantage. Since we did not study statistically significant numbers of patients with other acute lung diseases (post traumatic acute respiratory failure, pneumocystis carinii pneumonia, fulminant pulmonary embolism, etc.) no conclusion can be drawn on the relative probability of survival from these diseases with bypass therapy. However, none of the six study post-trauma patients or nine pulmonary embolism patients survived. Thus those physicians with expertise and confidence in both bypass and standard respiratory therapy may, if they wish, continue to use partial perfusion to treat these more reversible severe acute lung disorders. Others may choose not to employ this treatment as it remains more expensive, time consuming and difficult to carry out than mechanical ventilation [3 ]. Thus the membrane lung has been proven to be as limited as such other mechanical assistance devices as the intraaortic balloon pump and haemodialysis machine. While each supports a vital body function, it cannot heal the injured organ. The usefulness of membrane lung therapy now awaits advancements in our understanding of severe acute lung disease. Many investigators are proceeding to unravel the complex pathophysiology of this fulminant and frightening syndrome of diverse etiology which claims the lives of 90% of those it attacks. For some, the bypass machine will provide a tool to analyse the pulmonary circulation and understand the major increase of pulmonary vascular resistance [4]. Others will probe the pathology, physiology and pharmacotherapy of these diseases. Technology now has outstripped our knowledge of respiratory pathophysiology. The time has come to focus our energies and resources on understanding the basis of acute pulmonary injury; we must interrupt the destructive processes. Then, buying time with membrane lungs will also buy survival.