Treatment of pneumothorax

A small pneumothorax of volume less than 20 per cent of the hemithorax in an asymptomatic patient can be treated conservatively. Only observation to avoid complications may be indicated. If room air (21 per cent oxygen) is in the pleural space, the daily expansion of the lung is about 1.25 per cent of the lung volume. Spontaneous resolution of the pneumothorax depends on the nitrogen gradient between the intrapleural gas and the surrounding tissue. Therefore an increase in the nitrogen gradient by breathing oxygen accelerates the reabsorption. A large pneumothorax (more than 20 per cent of the hemithoracic volume) should be treated either by needle aspiration or preferably by chest tube thoracostomy. Owing to the high recurrence rate, pleurodesis (with talc, tetracycline, fibrin glue, etc.) is recommended in spontaneous pneumothorax. Once a pneumothorax results in impaired oxygenation or circulatory symptoms the placement of a chest tube is mandatory. Reinflation of the lung can be improved by negative suction on the chest tube.

In mechanically ventilated patients, a pneumothorax must always be drained with a chest tube because of the high risk of developing tension pneumothorax. For the same reason it is advisable to place a chest drain prophylactically in patients with otherwise uncomplicated pneumothorax if general anesthesia and positive-pressure ventilation is planned.

Persistent large bronchopleural fistulas are frequently a problem during mechanical ventilation. Often a significant part of the inspired air leaves the lung via the fistula. CO2 removal might be impaired if the bypassing air does not participate in gas exchange, but this can often be solved by increasing the inspired minute ventilation. However, a large air leak can result in a decrease of the mean intrapulmonary pressure and development of alveolar collapse, particularly in volume-controlled ventilation. Thus, pressure-controlled ventilation with a constant inspiratory airway pressure might be more advantageous. Although successful in infants, high-frequency ventilation in adults with large bronchopleural fistulas failed to improve gas exchange or to decrease gas flow through the fistula compared with conventional ventilation. Occasionally, in unilateral fistulas, independent lung ventilation facilitates individual adaptation of the ventilatory setting. While the intrapulmonary pressure in the lung with the fistula can be decreased to support sealing, gas exchange can be maintained by ventilation of the other lung.

Chapter References

Connolly, J.P. (1993). Hemodynamic measurements during a tension pneumothorax. Critical Care Medicine, 21, 294-6.

Dreyfuss, D., Soler, P., Basset, G., and Saumon, G. (1988). High inflation pressure pulmonary edema. Respective effects of high airway pressure, high tidal volume, and positive end-expiratory pressure. American Review of Respiratory Disease, 137, 1159-64.

Gammon, R.B., Shin, M.S., and Buchalter, S.E. (1992). Pulmonary barotrauma in mechanical ventilation. Patterns and risk factors. Chest, 102, 568-72. Gustman, P., Yerger, L., and Wanner, A. (1983). Immediate cardiovascular effects of tension pneumothorax. American Review of Respiratory Disease, 127, 171-4.

Macklin, C.C. and Macklin, M.T. (1944). Malignant interstitial emphysema of the lungs and mediastinum as an important occult complication in many respiratory diseases and other conditions: an interpretation of the clinical literature in the light of laboratory experiment. Medicine, 23, 281-352.

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