The effect of vasopressin on oxygen availability

Annals of Surgery (Impact Factor: 8.33). 05/1979; 189(4):439-41. DOI: 10.1097/00000658-197904000-00009
Source: PubMed


Vasopressin has been used with increasing frequency to control gastrointestinal bleeding, the beneficial effect being attributed to marked splanchnic vasoconstriction. Because vasopressin may result in impaired cardiac function and because other potent vasoconstrictive substances have been shown to increase the pulmonary shunt and decrease arterial oxygenation, this study was undertaken to determind the effect of vasopressin on oxygen availability. Ten healthy anesthetized mechanically ventilated dogs received a five hour intravenous vasopressin infusion, 0.005 U/kg/min. The heart rate decreased moderately and briefly. The mean systemic arterial pressure increased and then decreased, both minimally. The pulmonary shunt and the arterial oxygen content decreased slightly. The total systemic resistance increased and the stroke volume decreased, both substantially. The pulmonary artery wedge pressure gradually increased. The oxygen availability decreased markedly. This study demonstrated that a vasopressin infusion causes a marked decrease in oxygen availability due primarily to a decreased stroke volume and, to a lesser extent during the first hour, to a decreased heart rate. The pulmonary shunt did not increase. Increased systemic resistance followed by a gradual increase in the pulmonary wedge pressure suggests that the decreased stroke volume resulted, at least in part, from an increased afterload and left ventricular failure. It is suggested that until the effect of vasopressin on the cardiopulmonary systems and hence oxygen availability is fully studied in critically ill patients, that it be used with caution and with appropriate hemodynamic monitoring.

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    • "This effect is seen, for example, with phenylephrine, which has almost pure α-adrenergic effects. Vasopressin may also decrease cardiac output by increasing vascular tone [8-10]. Considering our analogy, this effect may be expected – increasing the slope of the road, or making the surface too uneven, will eventually force most cyclists to get off their bicycles and walk, thus reducing their speed considerably! "
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    ABSTRACT: Cardiac output is the amount of blood the heart pumps in 1 minute, and it is dependent on the heart rate, contractility, preload, and afterload. Understanding of the applicability and practical relevance of each of these four components is important when interpreting cardiac output values. In the present article, we use a simple analogy comparing cardiac output with the speed of a bicycle to help appreciate better the effects of various disease processes and interventions on cardiac output and its four components.
    Preview · Article · Sep 2008 · Critical care (London, England)
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    ABSTRACT: We have investigated the effects on systemic, pulmonary, hepatic, and renal hemodynamics, and on blood gases of vasopressin, 0.4 U/min I.V. first alone, then in combination with nitroprusside 1-5 micrograms/kg/min I.V., in 12 patients with liver cirrhosis and portal hypertension. Portal pressures were estimated by the gradient between occluded and free hepatic vein pressures, hepatic blood flow was measured by indocyanine green infusion, renal blood flow by an isotopic method, and cardiac output by thermodilution. Vasopressin alone reduced cardiac output (-23%) and O2 delivery to the tissues (-25%), increased mean arterial pressure (+20%) and filling pressures of the heart (+136%), reduced portal pressures (-36%) (from 19 +/- 1 to 12 +/- 1 mmHg, mean +/- SEM), hepatic blood flow (-35%) (1.33 +/- 0.2 to 0.87 +/- 0.1 l/min), and renal blood flow (-16%) (0.77 +/- 0.07 to 0.65 +/- 0.05 l/min). Adding nitroprusside restored cardiac output, preload and afterload, and renal blood flow to pretreatment values. Oxygen delivery remained depressed (-12%) because of a negative effect on pulmonary gas exchange (physiologic shunt increased from 16 +/- 2 to 28 +/- 4%). Portal pressures remained reduced by 31% and hepatic blood flow by 25%. These results suggest that small doses of I.V. nitroprusside minimize the deleterious hemodynamic effects of vasopressin while maintaining the therapeutic benefit of portal pressure reduction in cirrhotic patients.
    Full-text · Article · Mar 1984 · Annals of Surgery
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