Chest
Volume 92, Issue 3, September 1987, Pages 481-485
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Clinical Investigations
Continuous Positive Airway Pressure and Supplemental Oxygen in the Treatment of Cardiogenic Pulmonary Edema

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The efficacy of continuous positive airway pressure (CPAP) administered with a face mask was compared to oxygen supplementation in 40 patients with acute cardiogenic pulmonary edema. Baseline arterial blood gas values and pH, heart rate, respiratory rate, and blood pressure were recorded after patients breathed 28 percent oxygen with an ambient airway pressure for ten minutes. Thereafter, inspired oxygen concentration (FIo2) was increased by 0.10 and airway pressure was increased by 10 cm H2O in random sequence. Cardiopulmonary function was reassessed after a five-minute stabilization period at each level of oxygen supplementation and airway pressure. An increase in FIo2 and the application of CPAP both produced significant elevation in arterial blood oxygen tension. Use of CPAP was consistently associated with a decrease in respiratory rate, blood pressure, and rate pressure product, which were not observed with a mere enhancement of oxygen therapy. The improvement in the measured cardiopulmonary variables associated with CPAP therapy cannot be achieved by reversing hypoxemia with supplemental oxygen only.

Section snippets

Patients

The study group consisted of 40 patients who had respiratory failure with clinical and roentgenographic evidence of acute alveolar pulmonary edema of cardiac origin. The diagnostic criteria for respiratory failure were as follow: difficulty in breathing spontaneously expressed by the patient; signs of increased respiratory work, such as intercostal and suprasternal retractions or use of accessory respiratory muscles during inspiration; respiratory rate of more than 25 breaths per minute; or

RESULTS

The two groups were found to be comparable with regard to age, gender, underlying cause of pulmonary edema, cardiothoracic ratio, medical treatment (Table 1), and baseline cardiopulmonary function (Table 2). The study was not interrupted in any patient. No complication could be attributed to the type of therapy or to the equipment used.

DISCUSSION

Several reports describe a favorable therapeutic response to CPAP in patients with acute cardiogenic respiratory failure.1, 2, 4 An increase in functional residual capacity improves both gas exchange and the mechanical function of the lung producing simultaneous improvement in arterial blood oxygenation and reduction in respiratory work.7 Relief of respiratory distress with CPAP has been shown to be associated with significant hemodynamic improvement, reversal of hypertension and tachycardia,

ACKNOWLEDGMENTS

The authors wish to thank the physicians and the nursing staff of the Emergency Department and the Intensive Care Unit of the Helsinki University Central Hospital for their cooperation during this study, John B. Downs, M.D., for reviewing the manuscript, and Mary L. Tigner for editing it for style.

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Manuscript received July 21 revision accepted January 22.

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