ATRIAL-NATRIURETIC-PEPTIDE RELEASE IN RESPONSE TO DIFFERENT POSITIVE END-EXPIRATORY PRESSURE LEVELS

Objective. To assess the influence of different positive end-expiratory pressure (PEEP) levels on plasma atrial natriuretic peptide concentrations. Design: Prospective, randomized study. Setting. Intensive care unit of a university hospital. Patients. Twenty-seven patients who were mechanically ventilated due to acute respiratory failure. Intervention: None. Measurements and Main Results. The patients were randomized into three groups: in each group, a defined PEEP level (5, 10, or 15 cm H2O, respectively) was applied, alternating with zero PEEP (0 cm H2O) in consecutive order (reversal experiment). Blood samples for the determination of atrial natriuretic peptide concentrations were drawn from the pulmonary artery and the radial artery catheters. There were no decreases in atrial natriuretic peptide concentrations with a PEEP of 5 cm H2O, but significant decreases could be shown for PEEP values of 10 and 15 cm H2O. The patients of all groups were subjected to PEEP levels of 5, 10, 15, and 20 cm H2O in randomized order (step experiment). The data demonstrated a significant inverse correlation between changes in PEEP levels and changes in plasma atrial natriuretic peptide concentrations. Conclusion: The data suggest that the release of atrial natriuretic peptide is influenced by a PEEP of greater-than-or-equal-to 10 cm H2O, while a PEEP of less-than-or-equal-to 5 cm H2O does not disturb this cardiac endocrine function.