Clinical applications of body ventilators.

Interest has been increasing in providing ventilatory support in the home for patients with chronic respiratory failure, mainly with the use of positive pressure ventilation via a chronic tracheostomy. However, body ventilators that assist ventilation by applying intermittent negative or positive pressure to the thorax, abdomen, or airway without requiring an artificial airway, can offer distinct advantages for selected patients over systems requiring a permanent airway. These ventilators include the iron lung, portable lung (Portalung), pneumowrap, chest cuirass, pneumobelt, rocking bed, and positive pressure provided via a face or nose mask. They have successfully stabilized or reversed chronic hypercarbia when used intermittently in patients with slowly progressive chronic respiratory failure due to certain neuromuscular diseases and kyphoscoliosis. How they achieve this stabilization has not been clarified, but reversal of chronic respiratory muscle fatigue following periodic rest probably contributes. These ventilators are generally less effective than positive pressure ventilation through a tracheostomy and should be reserved for patients with relatively stable chronic respiratory failure and intact upper airways. However, they have the advantages of simpler operation and less expense, and they allow maintenance of a normal airway.