Effect of Hypothermia During Cardiopulmonary Bypass on Peripheral Resistance

Lopez-Belio, M; Tasaki, G; Balagot, Reuben C.; Sánchez-Valdeón, Leticia; Gómez, Francisco; Julian, Ormand C.

doi:10.1001/archsurg.1960.01300020111017

Cited by 13 publications

(1 citation statement)

References 6 publications

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“…Although various studies have reported the apparent loss of vascular tone induced by perfusion hypothermia (Peirce and Law, 1962;Neville et al, 1961;Ankeney and Murthy, 1962;Sealy et al, 1963;Lesage et al, 1962), and still others have measured the effects of both perfusion and surface cooling on arterial resistance (Oz et al, 1960;Sealy et al, 1963;Lesage et al, 1962;Sealy et al, 1958;Lopez-Belio et al, 1960;Salisbury et al, 1963;Svanes et al, 1970;Chen and Chien, 1977), changes in venous compliance, unstressed vascular volume, and venous resistance have not been reported. In contradistinction, there is abundant literature, most recently summarized by Chen and Chien (1977), covering the effects of all types of hypothermia on fluid balance.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of the increased vascular capacity produced by mild perfusion hypothermia in the dog.

Green¹,

Jackman²

1979

Circulation Research

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SUMMARY The mechanism of the increased vascular capacity produced by perfusion hypothermia was investigated in 20 anesthetized dogs. A right heart bypass preparation separated cardiac output (CO) into splanchnic (Q.) and nonsplanchnic (termed peripheral, Q p ) flows. Each channel drained by gravity into an external reservoir. Blood was then returned to the pulmonary artery at a constant flow of 80 ml/kg per min. Venous resistance and compliance of splanchnic (Ry, and C,) and peripheral (Rv p and Cp) channels were calculated from transient and steady state volume shifts which occurred following rapid drops in venous pressure. Arterial pressure (P.), hematocrit (H), plasma protein concentration, and changes in reservoir volume (AV^.) were also measured. PERFUSION hypothermia is the means by which body temperature can be lowered by selectively cooling the temperature of blood passing through an extracorporeal circuit. It has been long recognized that mild perfusion hypothermia (decreasing temperature to around 30°C) produces a decrease in extracorporeal reservoir blood volume at constant pump flow or a decrease in venous return at constant blood volume (i.e., an increase in vascular capacity) in both man and dog (Brown, 1962;Drew, 1966;Gollan et al., 1952;Yeh et al., 1961;Lindberg, 1959;Oz et al., 1960;Pierucci et al., 1960). Although there are several books (Cooper and Ross, 1960;Blair, 1964;Popovic and Popovic, 1974) and innumerable papers in the literature covering the subject of hypothermia, there are relatively few physiological reports of the effects of perfusion hypothermia. Furthermore, a review of the literature indicates that differences of opinion exist concern- ing the mechanism(s) of the increase in vascular capacity produced by perfusion hypothermia. This study was undertaken in an attempt to clarify the mechanism(s) responsible for this increase in vascular capacity. Methods Surgical ProceduresTwenty mongrel dogs with a mean weight of 23.0 ± 0.53 (SE) kg were anesthetized with sodium thiamylal, 18 mg/kg, iv. The anesthesia was maintained with 70% nitrous oxide in oxygen and halothane. A tracheotomy was performed and the dog was ventilated at an appropriate tidal volume and frequency for its size. A ventral laparotomy was then performed, followed by a splenectomy. The abdominal incision was not closed. The extracorporeal perfusion system used in this study (Fig. 1) has been described previously (Green, 1977;Green et al., 1978aGreen et al., , 1978b. In brief, the hepatic venous outflow of the splanchnic circulation and the circulation from the rest of the body, the peripheral channel, were isolated and cannulated. The venous return from these beds drained by gravity through separate Starling resistors and a Carolina Medical square wave electromagnetic flowmeter into an exby guest on

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