Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of halothane, ether, carbon dioxide, and perfusion rewarming on the electrocardiogram was studied in 37 dogs subjected to surface-induced deep hypothermia. Significant anesthetic-related differences in P-R, QRS, Q-T and R-R intervals during cooling were not apparent; however, reduced arterial pressure, ventricular fibrillation, and a greater tendency for bradycardia requiring supportive measures were noted at low temperatures with halothane anesthesia. The use of 95% O2/5% CO2 significantly reduced the QTc at low temperatures; Other phenomena, including the occurrence and significance of J waves, are discussed. The relationship of the electrocardiogram to clinical and pathological results was evaluated and indicates that (1) properly managed resuscitation (manual massage and defibrillation) is not a serious hazard, (2) ether in 100% oxygen is the agent of choice for surface-induced deep hypothermia with prolonged circulatory arrest, and (3) halothane may be used in a procedure combining surface cooling and perfusion rewarming if given in a mixture of oxygen and carbon dioxide.
 ...
PMID:Electrocardiographic changes during surface-induced deep hypothermia. The influence of ether, halothane, carbon dioxide, and perfusion rewarming. 112 62

A computer controlled ventilation system was employed to maintain a constant end-expired CO2 percentage (FECO2) during a series of studies on young dogs aimed at measuring brain temperature differences during surface cooling hypothermia. The conclusion is that an FECO2 of six per cent or more is desirable if brain temperature differences are to be minimized. Additional experiments showed that ethyl alcohol and sodium nitroprusside infusions during cooling did not decrease brain temperature differences.
 ...
PMID:Computer controlled studies in surface cooling hypothermia: the effect of carbon dioxide on brain temperature. 125 90

Variations of the phosphate concentration in plasma were studied in two groups of 12 patients undergoing cardiac surgery with hypothermic cardiopulmonary bypass (CPB). Management of the acid-base status differed between the groups, according to whether or not carbon dioxide was added to the anesthetic gas mixture during hypothermia ('pH-stat' vs. 'alpha-stat' mode) following correction vs. no correction of pCO2 and pH for body temperature. Phosphate variations throughout the study were mostly within normal limits. From the start to the end of CPB, the mean rise in phosphate levels was 70% in the pH-stat group and 37% in the alpha-stat group (p < 0.001). During 3 hours after CPB, the phosphate values continued to rise by a mean of 25% in the alpha-stat patients, but fell by a mean of 3% in the pH-stat patients (p < 0.001). Such different phosphate patterns during and immediately after CPB may reflect profound metabolic disturbances and may be related to the altering effects of CO2 addition and respiratory acidosis on intracellular metabolic activity and phosphate homeostasis.
 ...
PMID:Effect of acid-base management with or without carbon dioxide on plasma phosphate concentration during and after hypothermic cardiopulmonary bypass. 143 46

The effects of temperature, halothane concentration, and arterial partial pressure of CO2 on corticomotor evoked potentials (CMEPs) and somatosensory evoked potentials (SSEPs) were studied. Hypothermia causes an increase in CMEP and SSEP latencies. Corticomotor evoked potential amplitude increases with hypothermia to reach a maximum at or below 28 degrees C. As the temperature decreases from 42 degrees C, SSEP amplitude initially increases to reach a maximum between 36 and 34 degrees C and then decreases with further reductions in temperature. Increased arterial partial pressure of CO2 decreases amplitude and increases latencies of the CMEPs and SSEPs. The concentration of halothane has no effect on CMEP amplitude or latency. However, SSEP amplitude is inversely related to halothane concentration, and SSEP latency is directly related to halothane concentration. These results suggest that physiologic variables must be carefully measured when evoked potentials are utilized in any animal or human study. Moreover, each type of evoked potential has a unique response to alterations of these variables.
 ...
PMID:Variations in corticomotor and somatosensory evoked potentials: effects of temperature, halothane anesthesia, and arterial partial pressure of CO2. 156 29

O2 consumption (VO2), CO2 production (VCO2), and minute ventilation (VE) have been measured during normoxia and hypoxia (10-20 min in 10% O2) in specimens of 27 species from 6 mammalian orders, ranging in body mass (M) from a few grams to several kilograms. In normoxia, both metabolism and VE scaled close to M3/4, VE/VO2 and VE/VCO2 therefore being independent of M. In hypoxia, VE/metabolism increased in all species (on average greater than 100%), mostly because of a drop in VO2. On average, VE was 23% above the normoxic value but in some species decreased below normoxia. VO2 dropped in all but one species, on average 35%. Body temperature decreased by variable amounts, usually more in the smallest species. The decrease in metabolism during hypoxia was positively correlated with the resting metabolic rate of the species in a manner very similar to what can be calculated from data of previously studied newborn mammals. Hence hypoxia may decrease metabolic rate by decreasing thermogenesis, with larger effects in smaller animals, whether newborns or adults, because of their higher thermogenic requirements. We conclude that 1) hypoxic hypometabolism is a general characteristic of the mammalian response to hypoxia and cannot be neglected in the interpretation of ventilatory and cardiovascular responses and 2) its magnitude is inversely related to the resting VO2 of the species and therefore could be less prominent or possibly absent in adults of larger species.
 ...
PMID:Metabolism and ventilation in acute hypoxia: a comparative analysis in small mammalian species. 162 57

In pigeons, during shallow nocturnal hypothermia induced by food deprivation, body temperature falls to values between 35 degrees C and 38 degrees C. Body temperature, oxygen consumption, and arterial blood pH and PCO2 were recorded during the entrance into such nocturnal hypothermic periods. In vivo pH was kept constant, while in vivo PCO2 increased slightly during hypothermia. This caused the temperature-corrected value of pH (pH*, measured at 40 degrees C) to fall by -0.014 units/degrees C, and the total CO2-content to rise by 3.2 mM, an increase of 16%. These changes in the acid-base balance represent, in effect, a respiratory acidosis that closely parallels the normal buffer line for pigeons. Q10 values, relating oxygen uptake to body temperature, were higher than 4.0 at the very beginning of the entrance into hypothermia, indicating that the metabolic rate was actively inhibited. However, the present results do not indicate any relationship between the acidosis and the inhibition of the metabolic rate.
 ...
PMID:Oxygen consumption and acid-base balance during shallow hypothermia in the pigeon. 162 38

Weaning of patients from IPPV after cardiopulmonary bypass (CPB) is usually monitored by frequent arterial blood gas analysis. Non-invasive monitoring has the advantage of providing continuous and instantaneous information and could reduce the frequency of arterial blood gas sampling. Twenty patients were studied to determine the reliability of capnometry and pulse oximetry in this situation. The effects of hypothermia and moderate haemodynamic instability were examined. A further 40 patients were then weaned using non-invasive monitoring. Correlation between PaCO2 and PETCO2 was 0.64-0.79 for the mass spectrometer and 0.67-0.81 for the infra-red analyser. No clinical problems arose. The detection rate for mild hypercarbia was 78.6 per cent and 50 per cent for hypoxia. Possible reasons for this are discussed. Once CO2 and O2 gradients are established, pulse oximetry and capnometry provide sufficiently reliable monitoring to enable weaning from IPPV, with the advantage of continuous display, and allow a reduction in the use of arterial blood gas analyses.
 ...
PMID:Weaning from ventilation after cardiopulmonary bypass: evaluation of a non-invasive technique. 175 13

Canine thyroid tissue (CTy) was subjected to hyperbaric oxygen culture (HOC) under conditions that affect immunoalteration in murine thyroid tissue (MTy). Survival of autografts and allografts implanted under the kidney capsule was determined after 21 days by 125I uptake and histology. Unlike MTy, autograft CTy subjected to normothermic HOC (95% O2, 5% CO2; 1.76 kg/cm2) for 48 h did not survive (0/8) whereas decrease of culture duration to 24 h resulted in autograft CTy survival (3/3). Under hypothermia (5 degrees C), HOC could be extended to 7 days with autograft CTy survival (3/3 after 4 days and 3/3 after 7 days). Allograft CTy after 24 h of normothermic HOC and 7 days of hypothermic HOC was rejected. Indicators of oxygen free radical injury were determined:catalase activity was comparable in MTy and CTy (means 14.82 and 6.3-10.8 mm/mg protein, respectively) but superoxide dismutase activity was low in CTy (means 0.01-0.29 and 4.75 U/mg protein, respectively). Malondialdehyde content after 48 h of normothermic HOC was higher in CTy than in MTy (means 2215 and 1275 nmol/g, respectively). The results show that CTy is injured by HOC under conditions tolerated by MTy, and that this difference is related to the greater sensitivity of CTy to oxygen free radical injury.
 ...
PMID:A comparison of the effects of hyperbaric oxygen culture on survival of murine and canine thyroid gland grafts. 191 Apr 28

The effect of pentobarbital anaesthesia on spontaneous recovery from hypoxic apnoea (autoresuscitation) was investigated in SWR/J mice. Experiments were performed in 17 to 23 day old animals, in which the mechanism often fails, and in adults, in which it is usually successful. Mice, matched for age and weight, were injected with pentobarbital (62.5 mg/kg) or saline. Hypoxic apnoea was induced with 97% N2-3% CO2 and air given at its onset. To determine whether the effect of pentobarbital depended on hypothermia, we performed experiments in 17-23-day-olds with and without maintenance of body temperature. In the 'hypothermic' experiments one of 27 mice given pentobarbital died, compared with 10 of 22 controls (P less than 0.005). In the 'isothermic experiments', none of 15 mice given pentobarbital died, compared to 7 of 13 controls (P less than 0.005). All adults in both groups survived. Pentobarbital had a different effect on eupnoea and gasping: resting ventilation was depressed but gasp ventilation increased, and the duty cycle of gasps but not eupnoeic breaths was altered. Pentobarbital may facilitate autoresuscitation because gasping is unimpaired but oxygen consumption and lactate production are reduced, allowing cardiac function and cerebral survival until PO2 is restored.
 ...
PMID:Effect of pentobarbital on spontaneous recovery from hypoxic apnoea in mice. 192 12

Working rat hearts were perfused for 15 minutes at 37 degrees C before switching to a Langendorff perfusion (60 mm Hg aortic pressure) at 10 degrees C for 40 minutes of hypothermic arrest. Ventricular function was allowed to recover for 15 minutes at 37 degrees C by reestablishing the prehypothermic conditions. The perfusate was Krebs-Henseleit bicarbonate buffer containing 3% bovine serum albumin and either glucose (11 mmol/L) or glucose (11 mmol/L) plus palmitate (1.2 mmol/L) and gassed with 95% O2 and 5% CO2. In hearts receiving glucose alone as substrate, coronary flow was maintained constant during the 40 minutes of hypothermic arrest and returned to prehypothermic rates with rewarming. Ventricular function, as estimated by peak systolic pressure and heart rate, recovered to the prehypothermic level. When palmitate was added, coronary flow decreased continuously throughout the hypothermic perfusion (22% decrease by 40 minutes), and ventricular pressure development was lower throughout the rewarming perfusion. Tissue levels of adenosine triphosphate and creatine phosphate were well maintained and long-chain acyl coenzyme A and acyl carnitine decreased during hypothermia regardless of the substrate provided. With rewarming, tissue levels of adenosine triphosphate and creatine phosphate decreased in those hearts receiving palmitate. Omission of fatty acid either during hypothermia or during the first 5 minutes of rewarming improved recovery of function. Addition of oxfenicine to inhibit fatty acid oxidation, or inhibition of Ca2+ overload by verapamil and low perfusate Ca2+, prevented the effects of palmitate on ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Fatty acids suppress recovery of heart function after hypothermic perfusion. 192 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>