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Normobaric hyperoxia reduces cardiac index in patients after coronary artery bypass surgery
Johann M Harten1, Keith J Anderson, John Kinsella
1Department of Anaesthesia, University of Glasgow, Glasgow Royal Infirmary, Glasgow, United Kingdom. jharten@doctors.org.uk
Objective:
The purpose of this study was to assess the hemodynamic changes in response to normobaric hyperoxia in patients immediately after coronary artery bypass surgery.
Design:
Observational study.
Setting:
Single-center university hospital.
Participants:
Patients immediately after coronary artery bypass surgery.
Intervention:
Change of fractional inspired oxygen concentration from baseline (< or =0.60) to 1.0 and return to baseline.
Measurements And Main Results:
Cardiovascular changes were assessed with a lithium dilution technique. Cardiac index decreased from 2.82 to 2.52 L/min/m2 (10.6%). Heart rate decreased from 85.9 to 82.5 beats/min (4.0%), and the systemic vascular resistance index increased from 1,858 to 2,304 dyne/s/cm5/m2 (24.1%). Stroke index or mean arterial pressure did not change significantly. On reducing the FIO2 from 1.0 to the baseline FIO2 , there was significant reversal of the previous changes in heart rate and systemic vascular resistance. Heart rate increased from 82.5 to 84.0 beats/min (1.8%), and the systemic vascular index decreased from 2304 to 1932 dyne/s/cm5/m2 (16.1%). The cardiac output did not return to baseline, and the mean arterial pressure decreased from 69.6 to 64.4 mmHg (7.6%).
Conclusions:
Exposing patients after coronary artery surgery to hyperoxia induces significant hemodynamic changes.
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