Acute hyperoxaemia-induced effects on regional blood flow, oxygen consumption and central circulation in man

• Aim:  Despite numerous in vitro and animal studies, circulatory effects and mechanisms responsible for the vasoconstriction seen during hyperoxaemia are yet to be ascertained. The present study set out to: (i) set up a non-invasive human model for the study of hyperoxia-induced cardiovascular effects, (ii) describe the dynamics of this effect and (iii) determine whether hyperoxaemia also, by vasoconstriction alters oxygen consumption (O2).Methods:  The study comprised four experiments (A, B, C and D) on healthy volunteers examined before, during and after 100% oxygen breathing. A: Blood flow (mL min−1·100 mL−1 tissue), venous occlusion plethysmography was assessed (n = 12). B: Blood flow was recorded with increasing transcutaneous oxygen tension (PtcO2) levels (dose–response) (n = 8). C: Heart rate (HR), stroke volume, cardiac output (CO) and systemic vascular resistance (SVR) was assessed using echocardiography (n = 8). D: O2 was measured using an open circuit technique when breathing an air-O2 mix (fraction of inhaled oxygen: FiO2 = 0.58) (n = 8).Results:  Calf blood flow decreased 30% during O2 breathing. The decrease in calf blood flow was found to be oxygen dose dependent. A similar magnitude, as for the peripheral circulation, of the effect on central parameters (HR/CO and SVR) and in the time relationship was noted. Hyperoxia did not change O2. An average of 207 (93) mL O2 per subject was washed in during the experiments.Conclusion:  This model appears suitable for the investigation of O2-related effects on the central and peripheral circulation in man. Our findings, based on a more comprehensive (central/peripheral circulation examination) evaluation than earlier made, suggest significant circulatory effects of hyperoxia. Further studies are warranted to elucidate the underlying mechanisms.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

Nyckelord

blood flow

consumption

hyperoxaemia

hyperoxia

oxygen

vasoconstriction

MEDICINE

MEDICIN

Publikations- och innehållstyp

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