Continuous positive airway pressure improves oxygenation in dogs after the aspiration of blood.
Fourteen dogs were anesthetized, intubated, and breathed room air spontaneously. We then instilled 2 ml/kg of fresh nonheparinized donor blood into their tracheas. Seven dogs received no treatment and served as controls (group A); respiratory rate (RR) increased from 25 +/- 11 (mean +/- SD) to 103 +/- 33 breath/min, HR decreased from 179 +/- 28 to 136 +/- 42 beat/min, PaO2 decreased from 82 +/- 10 to 30 +/- 4 torr, pulmonary venous admixture (Qsp/Qt) increased from 0.14 +/- 0.10 to 0.72 +/- 0.06, and venous oxygen tension (PVO2) decreased from 46 +/- 4 to 22 +/- 5 torr 10 min after the aspiration of blood; all changes were statistically significant (p less than .05). After 4 h, RR and HR returned to control values, but PaO2 was only 58 +/- 10 torr. Cardiac output, oxygen consumption (VO2), and pulmonary and systemic BP and resistances were not significantly affected. Thirty-five min after the other 7 dogs aspirated blood (group B), 10 cm H2O of continuous positive airway pressure (CPAP) was applied while they breathed spontaneously. CPAP reduced Qsp/Qt to 0.31 +/- 0.10 and 0.15 +/- 0.11 30 and 90 min after its application, respectively (p less than .05). By 4 h, the PaO2 of group B dogs was 81 +/- 15 torr (p less than .05 compared with group A). CPAP also increased arteriovenous oxygen content difference (C[a-v]O2) compared with the nontreated dogs. Four hours after the aspiration of blood, all dogs were extubated. Twenty-four hours later, arterial blood gases were normal in all dogs of both groups.(ABSTRACT TRUNCATED AT 250 WORDS)