Study objectives: To determine the effects of hyperoxia on left ventricular (LV) function in humans with and without congestive heart failure (CHF).
Design: An acute physiologic study of the effect of hyperoxia on right-heart hemodynamics, LV contractility (peak positive rate of rise of LV pressure [+dP/dt]), time constant of isovolumic left ventricular relaxation (tau), and LV filling pressures.
Setting: Bayer Cardiovascular Clinical Research Laboratory at the Mount Sinai Hospital, Toronto, Ontario.
Patients: Sixteen patients with stable CHF and 12 subjects with normal LV function received the hyperoxia intervention.
Interventions: Patients received 21% O(2) by a nonrebreather mask, followed by 100% O(2) for 20 min, and 21% O(2) for a 10-min recovery period.
Results: In response to hyperoxia, there was a 22 +/- 6% increase in LV end-diastolic pressure (LVEDP) in the CHF group and a similar 29 +/- 14% increase in LVEDP in the normal LV function group (p < 0.05 for both; mean +/- SEM). Hyperoxia was also associated with a prolongation in tau of 10 +/- 2% in the CHF group (p < 0.05) and 8 +/- 2% in the normal LV function group (p < 0.05). No changes in +dP/dt were observed in either group.
Conclusions: Hyperoxia was associated with impairment of cardiac relaxation and increased LV filling pressures in patients with and without CHF. These observations indicate that caution should be used in the administration of high inspired O(2) fractions to normoxic patients, especially in the setting of CHF.