Respiratory and Metabolic Effects of Hypothermia

Dill, D. B.; Forbes, W. H.

doi:10.1152/ajplegacy.1941.132.3.685

Cited by 149 publications

(24 citation statements)

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“…occurring at 270 C. In the control series very slight changes were noted (Figure 1). Similar results have been described by others (6). The direct effect of cold on the sinus pacemaker appears to be responsible for the variations in heart rate.…”

Section: Pulse Ratesupporting

confidence: 90%

“…Variations in oxygen consumption up to 200%o which we observed in the four less deeply anesthetized dogs mentioned above were associated with marked shivering and increase in pulse rate. There is general agreement that shivering causes an increase in oxygen consumption (6 onset of shivering although such effects have been reported by others (7).…”

Section: Oxygen Consumptionsupporting

confidence: 54%

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The Cardiovascular Effects of Acutely Induced Hypothermia 12

Prec

Rosenman²,

Braun³

et al. 1949

J. Clin. Invest.

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with a mercury manometer. Pulse rates were obtained from electrocardiograms taken simultaneously with the other measurements.Cardiac output was calculated from the oxygen consumption and the arteriovenous oxygen difference according to Fick's formula (2). Two radio-opaque cardiac catheters were introduced through the external jugular veins and, with the aid of fluoroscopy, the distal ends were placed in the right auricle and in the pulmonary artery, respectively. The proximal ends of the catheters were connected with saline manometers for the recording of mean pressures. The location of the catheters and their zero pressures were verified at post-mortem examination. To ensure maximal mixing of the blood returning to the heart, samples of venous blood were taken from the pulmonary artery. Arterial blood was obtained from the cannulated femoral artery. In the course of each experiment, 100 to 150 cc. of blood were withdrawn and replaced with isotonic saline solution. The Van Slyke-Neill technic (3) was used in the analysis of blood Qa and CO2. Hematocrits were determined by the Wintrobe method (4), arterial blood being employed.Control measurements were made when the blood pressure and respiration of the animal became stabilized. The animals were then covered with chipped-ice packs. Body temperatures were recorded from thermometers placed deeply in the rectosigmoid area and protected from the ice packs. The mean cooling period was about two hours during which the body temperatures fell to 290 C. The animal was then dried, covered with thin sheets, and exposed to radiant heat. However, the body temperatures continued to fall to 270 C, before beginning to rise.The mean rewarming period lasted five to six hours, at the end of which body temperatures usually had returned to 37°C. Ten or 11 determinations were obtained in each experiment, measurements being taken after each 2 degree change of body temperature. Evaluation of the methodMeasurements of right auricular and pulmonary arterial pressures represent only the approximate mean values. The changes in pressure were considered to be of greater significance. During periods of extreme bradypnea resulting from severe respiratory center depression, great variations in concentration of blood gases occur during each respiratory cycle, and this produces errors in the direct Fick method. This inaccuracy is further increased by the fact that the usual means of collecting blood samples makes it impossible to obtain exactly 293

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Section: Pulse Ratesupporting

confidence: 90%

Section: Oxygen Consumptionsupporting

confidence: 54%

The Cardiovascular Effects of Acutely Induced Hypothermia 12

Prec

Rosenman²,

Braun³

et al. 1949

J. Clin. Invest.

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show abstract

“…On behalf of this difference, the P50 by the present method might be expected to be higher by 0.8 Torr than those by the gasometric procedure. Therefore, when corrected for this discrepancy the standard P50 value by us must be 26.8+1.1 Torr, which is almost identical with the previous values (DILL and FoRBES, 1941;BARTELS et al, 1961;SEVERINGHAUS, 1966;ENOKI et al, 1972). Hill's exponent, n (HILL, 1910) and CO2 Bohr coefficient agree with the published values of BARTELS et al (1961) andHLASTALA et al (1977).…”

Section: Discussionsupporting

confidence: 84%

“…Table 2 shows the comparison of the standard ODC data (pH 7.40, Pco2 40 Torr, 37°C) by our method with the previously published standard values (BARTELS et al, 1961;SEVERINGHAUS, 1966). These values agree well generally Japanese Journal of Physiology but our value for the P50 is a little higher (0.8-1.3 Torr) than those by DILL and FoRBES (1941), BARTELS et al (1961), andSEVERINGHAUS (1966). This difference may be caused by the technical errors inherent in the present procedure and/or by the actually higher P50 possessed by the present 25 Japanese adults.…”

Section: Discussionsupporting

confidence: 79%

A simple microtonometric method for whole blood oxygen dissociation curve and a critical evaluation of the "single point" procedure for blood P50.

et al. 1983

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We devised a rapid and simple method to obtain oxygen dissociation curve (ODC) for a small amount of blood with simple equipment. This system achieved the gas-blood equilibrium within 3 min. Oxygen saturation of the equilibrated blood was measured spectrophotometrically while the pH, Pco2, and Pot was measured with a Radiometer blood gas analyzer system. Whole procedures to construct ODC from the 6 point measurements could be performed within 1 hr. The standard ODC for 25 normal Japanese adults showed a mean P50 of 27.6±1.1 Torr (pH 7.40, Pco2 40 Torr, 37°C), a slightly higher value than previously reported. The discrepancy, however, can be eliminated when corrected for a slightly lower S02 by the present procedure. The standard curves for the adult blood at pH 7.20 and 7.60 and for the cord blood at pH 7.40 were also described. The "single point" procedure, a much quicker approach to measure the P50 (ABERMAN et al., 1975), was scrutinized by comparing with the "whole curve" method. The P50's by the two methods were not significantly different, mean±S.D. of the differences being 0.4±2.5 Torr (n=126) for the adult blood at pH 7.40, Pco2 40 Torr and 37°C. Similar results were obtained for the adult blood at pH 7.20 and 7.60 and for the cord blood at 7.40. We concluded that the "single point" method was sufficiently accurate and reliable.

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“…Shivering which, at least temporarily, accompanies hypothermia would elevate metabolism (16,41) and potentially diminish neuroprotection since lowered metabolism is probably one of the mechanisms by which hypothermia protects (1,10,23). Other neuroendocrine effects of unanesthetized hypothermia might also lessen protection.…”

Section: Figmentioning

confidence: 99%