Overview of improving tolerance of long-term mechanical ventilation.

In summary, advances in critical care and mechanical ventilation have resulted in an increased salvage of critically ill patients, a number of whom require long-term ventilation as a means of life support. In addition, the total number of patients receiving long-term ventilation has increased dramatically over the past couple of years, and they now are treated in many different locations throughout the health care delivery system (the intensive care unit, general medical floor, specialized weaning units, and the home). Moreover, patients who require long-term ventilation usually suffer from a complex blend of medical, physiologic, and psychological disorders that may impair tolerance of chronic ventilation.

Permissive hypercapnia in acute respiratory failure.

Objective: To evaluate the potential efficacy of pressure limitation with permissive hypercapnia in the treatment of acute respiratory failure/adult respiratory distress syndrome on the basis of current theories of ventilator-induced lung injury, potential complications of systemic hypercarbia, and available human outcome studies.

Data Sources: Articles were identified through MEDLINE, reference citations of published data, and consultation with authorities in their respective fields.

Study Selection: Animal model experimentation and human clinical trials were selected on the basis of whether they addressed the questions of pressure limitation with or without hypercapnia, the pathophysiologic effects of hypercapnia, or the concept of ventilator-induced parenchymal lung injury.

Performance of an intravenous gas exchanger (IVOX) in a venovenous bypass circuit.

To analyze quantitatively the performance of the intravenacaval blood gas exchanger (IVOX), we developed a right atrium-pulmonary artery venovenous extracorporeal bypass circuit. Oxygen transfer and carbon dioxide removal were calculated at different blood flow rates, different hemoglobin levels, and during permissive hypercapnia. Oxygen transfer increased linearly with blood flow up to 41 mL/min.