Left ventricular response to continuous positive airway pressure: role of left ventricular geometry.

BACKGROUND

Continuous positive airway pressure (CPAP) may be a useful adjunct in patients with congestive heart failure.

OBJECTIVES

To evaluate the relationship between left ventricular geometry and hemodynamic response to CPAP.

METHODS

Right heart catheter studies were performed in 26 patients before, during and after application of CPAP (8 cm H(2)O) over 15 min. Response to therapy was defined as an increase in stroke volume using CPAP.

RESULTS

Cardiac output decreased from 6.9 +/- 1.9 to 6.2 +/- 1.4 liters/min (p = 0.01) with a slight increase after cessation of CPAP (not significant). There was no significant change in stroke volume (92 +/- 34 vs. 90 +/- 31 ml, p = 0.584) or pulmonary capillary wedge pressure (14.7 +/- 7.0 vs. 14.2 +/- 6.5 mm Hg, p = 0.26). There was a correlation between hemodynamic effects of CPAP therapy and left ventricular end-diastolic volume (r = 0.515, p = 0.01), mass-volume ratio (r = -0.41, p = 0.04) and pulmonary capillary wedge pressure (r = 0.654, p = 0.001) at baseline. Half the patients (n = 13) were categorized as responders with an average increase in stroke volume of 11.5 +/- 2.1%. Responders showed significantly higher left ventricular end-diastolic volume, pulmonary capillary wedge pressure and lower mass-volume ratio.

CONCLUSION

Patients with high pulmonary capillary wedge pressure, elevated end-diastolic volumes and a low left ventricular mass-volume ratio might profit from CPAP therapy.