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PubMed2004

Differential expression of neuronal fos protein after cold water drowning and controlled rewarming.

BACKGROUND: Cardiopulmonary bypass has often been applied to revive victims of cold water drowning. The success of resuscitative efforts in patients who have sustained severe hypothermia is largely determined by neurologic outcomes. Measurement of Fos, the protein product of the immediate-early gene c-fos, is a marker of cerebral injury. STUDY DESIGN: Twenty-eight infant lambs were sedated and ventilated. Group 1 lambs were immersed in a cold water bath for 2 hours (17.3 +/- 2.7 degrees C). Group 2 lambs were placed on normothermic cardiopulmonary bypass for 2 hours (37.7 degrees +/- 0.7 degrees C). Group 3 lambs were immersed in a cold water bath for 2 hours (17.6 degrees +/- 2.4 degrees C), and then rewarmed for a period of 2 hours on cardiopulmonary bypass (37.0 degrees +/- 0.6 degrees C). The lambs were euthanized and immunohistochemical analysis for neuronal Fos was performed. RESULTS: There was significant induction of Fos-labeled nuclear profiles (cells/1130 microm(2)) in group 3 in the hippocampal regions and dentate gyrus compared with groups 1 and 2 (p < 0.001). CONCLUSION: Isolated exposure to either hypothermia or cardiopulmonary bypass results in minimal expression of neuronal Fos; the significant induction of Fos in the group 3 animals may represent an ischemic-reperfusion phenomenon. Modifications of rewarming techniques that minimize Fos expression may improve neurologic outcomes in victims of cold water drowning.

Animals↗
PubMed2001

Effects of epinephrine in a pig model of hypothermic cardiac arrest and closed-chest cardiopulmonary resuscitation combined with active rewarming.

OBJECTIVE: The aim of the current study was to assess the effects of epinephrine in a pig model of hypothermic cardiac arrest followed by closed-chest cardiopulmonary resuscitation combined with active rewarming, simulating the clinical management of an arrested hypothermic patient in a hospital without cardiopulmonary bypass facilities. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: Twelve 12- to 16-week-old domestic pigs. INTERVENTIONS: Pigs were surface cooled to a body core temperature of 28 degrees C. After 4 min of untreated cardiac arrest, manual closed-chest CPR and thoracic lavage with 40 degrees C warmed fluid were started. After 3 min of external chest compression animals were randomly assigned to receive epinephrine (45, 45 and 200 microg/kg) or saline placebo in 5-min intervals. MEASUREMENTS AND MAIN RESULTS: Coronary perfusion pressure was about 15 mmHg in placebo group pigs. Coronary perfusion pressure was significantly higher after epinephrine, but restoration of spontaneous circulation was not more frequent (one of six epinephrine versus three of six saline placebo pigs, P=0.34). After 45 microg/kg epinephrine the arterial PO(2) was significantly lower when compared to the saline placebo. The third 200 microg/kg epinephrine dose resulted in a significantly enhanced mixed venous hypercarbic acidosis. CONCLUSIONS: After a short 4-min period of hypothermic cardiac arrest, epinephrine may not be necessary to maintain coronary perfusion pressure around the threshold usually correlating with successful defibrillation, even during prolonged closed-chest CPR combined with active rewarming. The enhanced mixed venous hypercarbic acidosis in epinephrine-treated animals may support the argument against repeated or high dose epinephrine administration during hypothermic CPR.

Analysis of Variance↗
PubMed2002

Effects of haemodilution and rewarming with regard to digital amputation in frostbite injury: an experimental study in the rabbit.

Peripheral vascular failure with haematological and haemodynamic changes occurs after frostbite injuries. In order to study the effects of normovolemic haemodilution on the extent of digital necrosis, the paws of rabbits were haemodiluted and frozen to -15 degrees C. Dextran or gelatin was used as the plasma substitute in two groups and the rewarming after the cold injury was performed either at room temperature (22 degrees C) or with hot water baths (38 degrees C). The extent of necrosis was significantly less in the rabbits haemodiluted with dextran or gelatin and rewarmed in hot water baths.

Amputation, Surgical↗
PubMed2004

Unusual complications after rewarming for deep accidental hypothermia.

Deep accidental hypothermia is an uncommon pathology. Successful management has been reported in isolated cases, but the majority of patients die from complications after rewarming. We report on a patient with deep accidental hypothermia after a mountaineering accident. He was successfully rewarmed with cardiopulmonary bypass, but presented several complications which led to death. These complications included the patient developing acute peritonitis and necrotizing fasciitis, which represent, to our knowledge, complications that have never been associated with deep accidental hypothermia before.

Fasciitis, Necrotizing↗
PubMed2004

Continuous measurement of cerebral blood volume and oxygenation during rewarming of neonates.

AIM: To investigate the effect of rewarming in preterm infants presenting with hypothermia at admission. METHODS: The tissue oxygenation index (TOI), changes in cerebral blood volume (DeltaCBV) and changes in intravascular oxygenation (DeltaHbD) were measured in eight preterm infants, presenting with a temperature less than 35 degrees C at admission. RESULTS: A significant increase in HbD and TOI was seen in four patients (group A), while a significant increase in CBV and a decrease in HbD was seen in four other patients (group B). Retrospective analysis showed that group A had important signs of peripartal asphyxia. CONCLUSION: While infants with peripartal asphyxia showed an important increase in oxygenation during rewarming, no significant changes were seen in the non-asphyxiated infants.

Asphyxia Neonatorum↗
PubMed2001

Negative pressure rewarming vs. forced air warming in hypothermic postanesthetic volunteers.

We compared changes in core temperature and systemic heat balance with a new negative pressure/warming device (Vital Heat(R) ) that uses negative pressure combined with heat to facilitate warming in vasoconstricted postoperative patients to those resulting from passive insulation or forced air. Seven healthy volunteers were anesthetized and cooled to a tympanic membrane temperature near 34 degrees C. Anesthesia was discontinued and shivering was prevented by using meperidine. The vasoconstricted volunteers were rewarmed for 2 h using three randomly assigned methods: 1) Vital Heat plus cotton blanket; 2) one layer of cotton blanket; 3) forced-air warming. Thermal flux was recorded from 15 skin-surface sites; metabolic heat production was estimated from total body oxygen consumption. Metabolic heat production remained constant throughout the study. Systemic heat loss remained constant during warming with cotton blankets but decreased significantly during the other treatments. Systemic heat balance increased significantly more with forced air (140 +/- 21 kcal) than with Vital Heat (66 +/- 19 kcal) or cotton blankets (47 +/- 18 kcal). Core temperature increased no faster with Vital Heat warming (1.3 +/- 0.4 degrees C) than with a cotton blanket (1.2 +/- 0.4 degrees C). In contrast, core temperature increased more rapidly with forced air warming (2.6 +/- 0.6 degrees C). In this study we show that calories from a negative pressure rewarming device are largely constrained to the forearm and that heat does not flow to the core thermal compartment.

Adult↗
PubMed1994

Efficiency of a new radiant heater for postoperative rewarming.

Effective rewarming devices have only become available recently. This investigation compares the efficiency of an new overhead radiant heater (ARAGONA Thermal Ceilings TM, CTCX, 1000 W) with that of an electric blanket (50 W) or a standard hospital blanket. 35 patients undergoing postoperative assisted ventilation and continued sedation were randomly assigned to one of the treatments. Shivering, oxygen uptake, heart rate and invasive blood pressure were measured and the increase in total body heat minus body heat production was calculated as heat balance. Results are given as medians (range). Subcutaneous temperatures were taken to calculate the mean skin temperature. The evaluation was undertaken for an oesophageal temperature interval of 35 degrees to 37 degrees C. All groups exhibited a similar mean oxygen uptake i.e. thermogenesis (3.5 (2.7-4.0) ml.kg-1.min-1, 3.3 (2.7-4.9) ml.kg-1.min-1;3.2 (2.4-5.1) ml.kg-1. min-1) which correspond to a resting energy expenditure. The time of rewarming of the radiant heat treated group (n = 12) (100 (76-143) min) for this interval was significantly reduced in comparison to both other groups (183 (116-320) min; 231 (115-340) min). A slightly positive heat balance was only achieved in the group treated by radiant heat, indicating that all metabolic heat was conserved or heat losses were compensated by transfer of external heat. Shivering was significantly reduced in the radiant heater group whereas the rate pressure product was insignificantly higher. We did not find any significant effect for the electric heating blanket in comparison to the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

Thermoregulatory responses of the newborn pig during experimentally induced hypothermia and rewarming.

Exposure to a temperature of 14 degrees C was used to induce a progressive hypothermia in fourteen conscious newborn piglets. Heat production, body (rectal) and skin (between the shoulders) temperatures and shivering intensity assessed as the electromyographic activity (EMG) of longissimus thoracis muscle were measured until body temperature reached 30 degrees C and during a recovery period of 2 h at an ambient temperature of 24 degrees C (n = 7) or 34 degrees C (n = 7). During body cooling, heat production increased up to 9.67 +/- 1.28 W (kg BW)-1, but started to decrease below a body temperature threshold of 34.4 +/- 0.7 degrees C. EMG activity increased (P < 0.023) curvilinearly during body cooling; the main increase occurred between body temperatures of 38 and 33 degrees C (+142%, P < 0.001), and changes in EMG activity between 33 and 30 degrees C were not significant (+18%, P > 0.1). A marked increase in circulating levels of glucose (+312%, P < 0.001), glucagon (+76%, P < 0.05), adrenaline (+172%, P < 0.05) and noradrenaline (+113%, P < 0.05) occurred during body cooling. Insulin levels were not detectable at 2 h of life and increased during body cooling. During 2 h of rewarming at 24 degrees C, heat production and EMG activity remained elevated, changes in carbohydrate metabolism were not completely reversed and the final body temperature was only 35.6 +/- 0.9 degrees C. Rewarming of the piglets was faster at 34 degrees C. There was a net influx of heat into the animals and heat production and shivering activity decreased when body temperature reached 33.9 +/- 0.5 degrees C; the final body temperature was 37.5 +/- 0.2 degrees C. Circulating levels of lactate, glucagon and catecholamines returned to control levels. These results show that in conscious piglets exposed to a constant cold temperature there is an inverse relationship between EMG activity and body temperature during moderate hypothermia and that the thermoregulatory response and carbohydrate metabolism of the piglet are seriously impaired below a body temperature of 34 degrees C.

Animals↗
PubMed1994

Effects of systemic cooling and rewarming on the evoked spinal cord potentials and local spinal cord blood flow in dogs.

Changes in evoked spinal cord potential (ESCP) and in local spinal cord blood flow (local SCBF) were measured simultaneously in eight dogs in the course of systemic cooling and rewarming using a water mattress. PaCO2 was maintained at 35-40 mm Hg (temperature-uncorrected values) by adjusting ventilatory volume every 1 degree C change of esophageal temperature under N2O (60%)-O2-isoflurane (1.15%) anesthesia. Local SCBF and arterial blood pressure decreased and ESCP latencies increased linearly with the decrease in body temperature to 23-24 degrees C. The conductive ESCPs (non-synaptic components) showed temporary augmentation in amplitude before eventual decrease under cooling. These showed a tendency to return to the precooling baselines after the initiation of rewarming. These results demonstrate that conductive ESCPs could be available for intraoperative monitoring of spinal function under hypothermia down to 23-24 degrees C.

Animals↗
PubMed2002

[Efficacy of propofol in controlling myoclonus during rewarming in a brain hypothermia patient].

Propofol is an intravenous anaesthetic agent having anticonvulsant property. We report here a case in which propofol was effective in controlling myoclonus during rewarming in brain hypothermia patient. A 35-year-old male patient was admitted in a comatose state with right-sided hemiparesis, anisocoria and absence of bilateral light reflex. On admission, a head CT showed traumatic subarachnoid hemorrhage, left subdural hematoma, 10 mm midline shift and tentorial herniation with massive brain swelling together with extensive hypodensity in the frontal, temporal and occipital lobes bilaterally. Left decompressive hemicraniectomy, removal of hematoma and brain hypothermia therapy were started immediately. Postoperative head CT showed 15 mm midline shift. The temperature of the jugular bulb was maintained at 34 degrees C for 2 days together with sedation using midazolam under artificial ventilation. The patient was gradually rewarmed at a rate of 0.5 degree C per day from the third hospital day. Myoclonus of sudden onset developed on the patient's head and upper extremities on the third hospital day. An intravenous bolus injection of 10 mg midazolam and continued intravenous infusion of midazolam were given but they did not completely stop myoclonus. A bolus of propofol 60 mg was given intravenously and continuous intravenous infusion of propofol 2 mg.kg-1.hr-1 was started after which the progression of myoclonus disappeared. Myoclonus was kept controlled until the continuous intravenous infusion of midazolam and propofol was discontinued on the sixth hospital day, after which myoclonus occurred again after extubation on the seventh hospital day. The clinical course of this case suggests that propofol might be an alternative effective agent to suppress refractory myoclonus.

Adult↗
PubMed2004

Efficacy of postoperative rewarming after cardiac surgery.

OBJECTIVE: To compare the efficacy of forced-air warmers and radiant heaters on rewarming after cardiac surgery in a prospective randomized study. METHODS: Fifty male patients who had undergone coronary artery bypass graft surgery were studied. The control group (Gr. C, n=10) was nursed under a standard hospital blanket. Two groups were treated with forced-air warmers: WarmTouch 5700 (Gr. WT, n=10) and Bair Hugger 500 (Gr. BH, n=10). Two other groups were treated by radiant heaters: the Aragona Thermal Ceilings CTC X radiant heater (Gr. TC, n=10) and a self assembled radiant heater of 4 Hydrosun 500 infrared lamps (Gr. HY, n=10). Changes of oesophageal temperature, mean skin temperature, mean body temperature and relative heat balance were calculated from oesophageal temperature, 4 skin temperatures and oxygen consumption (VO(2)). RESULTS: All actively treated groups with exception of the TC group showed significantly faster oesophageal warming than the control group. The mean body temperature increased 1.1 (0.7-1.7) degrees Ch(-1) in Gr. WT, 1.3 (0.7-1.5) degrees Ch(-1) in Gr. BH, 0.8 (0.5-1.4) degrees Ch(-1) in Gr. TC and 0.7 (0.4-1.0) degrees Ch(-1) in Gr. HY compared to Gr. C with 0.4 (0.2-0.7) degrees Ch(-1). The mean VO(2) and the maxima of the VO(2) during the study period did not differ significantly between the groups. CONCLUSION: In the current setting active warming, forced-air warming more than radiant warming, increased speed of rewarming two- to threefold in comparison to insulation with a blanket.

Aged↗
PubMed1987

Rewarming of the hypothermic rhesus monkey with electromagnetic radiation.

To obtain more detailed information relative to the potential usefulness of using radio frequency (RF) energy in treating hypothermia, anesthetized rhesus monkeys were used in a rewarming study that compared a conventional method (heating pad) with an RF induction coil system. Rectal temperature (Tre) of each subject was monitored, and enzyme and isoenzyme levels were determined from blood samples collected before, during, and up to 48 h after hypothermia in order to assess the effects of each rewarming method. The previously observed postprocedure rise in serum enzymes (most visible at 24 h) was again seen, with no statistically significant difference in the time course of serum enzyme levels between the two treatments for comparable durations of hypothermia. To test the limits of the ability of the RF induction coil system, successively more severe hypothermia was induced in the subjects to the point of cardiovascular collapse (Tre less than 20 degrees C); RF energy was successful in resuscitating the profoundly hypothermic subjects without discernible harmful effects.

Alanine Transaminase↗
PubMed1999

Different tolerance to hypothermia and rewarming of isolated rat and guinea pig hearts.

We examined the effect of hypothermia and rewarming on myocardial function and calcium control in Langendorff-perfused hearts from rat and guinea pig. Both rat and guinea pig hearts demonstrated a rise in myocardial calcium ([Ca]total) in response to hypothermic perfusion (40 min, 10 degrees C), which was accompanied by an increase in left ventricular end diastolic pressure (LVEDP). The elevation in [Ca]total was severalfold higher in guinea pig than in rat hearts, reaching 12.9 +/- 0.8 and 3.1 +/- 0.6 micromol.g dry wt-1, respectively. The rise in LVEDP, however, was comparable in the two species: 62.5 +/- 2.5 (guinea pig) and 52.5 +/- 5.1 mm Hg (rat). Following rewarming, [Ca]total remained elevated in guinea pig, whereas a moderate decline in [Ca]total was observed in the rat (13.6 +/- 1.9 and 2.2 +/- 0.3 micromol.g dry wt-1, respectively). Posthypothermic values of LVEDP were also significantly higher in guinea pig compared to rat hearts (42.5 +/- 6.8 vs 20.5 +/- 5.1 mm Hg, P < 0.027). Furthermore, whereas rat hearts demonstrated a 78 +/- 7% recovery of left ventricular developed pressure, there was only a 15 +/- 7% recovery in guinea pig hearts. Measurements of tissue levels of high energy phosphates and glycogen utilization indicated a higher metabolic requirement in guinea pig than in rat hearts in order to oppose the hypothermia-induced calcium load. Thus, we conclude that isolated guinea pig hearts are more sensitive to a hypothermic insult than rat hearts.

Adenosine Triphosphate↗
PubMed1996

Taurine reduces experimental liver injury after cold ischemic preservation and a period of rewarming prior to reperfusion.

Livers of male Wistar rats (250-300 g) were isolated and flushed with 10 ml of Ringer's solution and 10 ml of UW preservation solution. Then the organs were stored for 24 h at 4 degrees C in UW solution. Livers of Group 1 were rinsed with 10 ml of Ringer's solution and reperfused after hypothermic storage with oxygenated Krebs-Henseleit solution (95% O2; 5% CO2) in a nonrecirculating system at constant pressure (10 mmHg) and 37 degrees C. Livers of Group 2 were incubated for 30 min at 37 degrees C prior to reperfusion, in order to simulate rewarming of the organ upon surgical implantation. Livers of Group 3 were treated like Group 2, but taurine was admixed to the UW solution (1 mM). Livers of Group 1 showed little signs of a preservation/reperfusion injury, with low enzyme activities of the parenchymal ALT and endothelial purine nucleoside phosphorylase (PNP) in the postischemic rinse solution (ALT: 19.9 +/- 12.4; PNP: 3.3 +/- 0.4 U/liter), adequate portal flow values about 3 ml/g/min and high O2 uptake at the end of the experiment (VO2: 3.2 +/- 0.4 ml/100g/min). Livers of Group 2 exhibited nearly tenfold higher enzyme activities in the rinse solution (ALT: 247.0 +/- 94.7*; PNP: 29.5 +/- 17.0* U/l) and disturbed tissue perfusion with significantly reduced flow values of about 2 ml/g/min during the first 10 min of reperfusion. As a result, the recovery of O2 uptake was only 2.2 +/- 0.3 ml/100 g/min*. Addition of taurine (Group 3) resulted in a significant reduction of the enzyme loss (ALT: 96.2 +/- 50.0#; PNP:12.4 +/- 7.0# U/liter) and improved portal flow values and O2 uptake at the end of reperfusion (2.7 +/- 0.3 ml/100 g/min#). The results give evidence for the importance of the rewarming period after hypothermic storage, which is inevitable during implantation of the organ in vivo. Taurine seems to exert a protective effect, affecting both the vascular endothelium and parenchymal tissue (*p < 0.05 vs Group 1; # p < 0.05 vs Group 2).

Adenosine↗
PubMed1992

Rewarming of feet by lower and upper body exercise.

The capacity of different types of exercise to rewarm the body, especially the feet, was studied. Six healthy male subjects wearing winter clothing (2.4 clo, 0.37 degrees C.m2.W-1) were exposed on three occasions to -15 degrees C for 120 min. For the first 60 min the subjects were cooled while sitting motionless and for the latter 60 min they were submitted to cycle ergometer exercise (CE), arm ergometer exercise (AE) or step exercise (ST). The rate of work in CE (about 350 W) served as a reference value for AE and ST. The cooling resulted in an average 1.7 (SEM 0.03) degrees C decrease in mean body temperature (Tb) corresponding to a 425 (SEM 9) kJ heat debt. The ST increased most effectively mean skin, rectal and lower body skin temperatures as well as dry heat loss. The ST increased Tb by 0.83 (SEM 0.16) degrees C, CE by 0.10 (SEM 0.11) degrees C and AE by only 0.07 (SEM 0.12) degrees C. At the end of the exercise the foot temperature was approximately 6 degrees C higher in ST than in CE. The superior rewarming by ST was apparently due to its low mechanical efficiency. Because the increase in Tb could not explain all the changes in foot temperatures, increased circulation and metabolism of the feet would also appear to have been involved.

Adult↗
PubMed1995

Effects of taurine on liver preservation in UW solution with consecutive ischemic rewarming in the isolated perfused rat liver.

Taurine (2-aminoethane sulfonic acid) is a physiologic amino acid involved in cellular osmoregulation in various species including man. This study was intended to compare the respective effects of cold storage and consecutive ischemic rewarming of the liver postischemic hepatic flow and hepatocellular outcome upon reperfusion with or without the addition of taurine to the preservation medium. Livers from male Wistar rats were rinsed free of blood via the portal vein and stored ischemically at 4 degrees C in UW solution. Livers from group 1 were then rinsed again with 10 ml Ringer's solution and reperfused with Krebs-Henseleit buffer at a constant pressure of 10 mmHg for 45 min at 37 degrees C in a nonrecirculating manner. Livers from groups 2 and 3 were subjected to 30 min of warm ischemia subsequent to cold storage and prior to reperfusion with 10 mM taurine added to the UW solution in group 3. While there were only very few signs of hepatic injury in group 1, the additional period of warm ischemia (group 2) led to a significant reduction in early perfusate flow and enhanced enzyme leakage from the livers during postischemic rinse and reperfusion. Livers in group 3 exhibited an amelioration in hepatic circulation and significantly reduced enzyme release as compared to group 2. The results clearly demonstrate a remarkable impact of postischemic rewarming on graft viability. Furthermore, the addition of taurine to the preservation medium was shown to improve hepatic circulation and enhance viability of the liver upon reperfusion.

Adenosine↗
PubMed1980

Enhancement of cooling and rewarming by a jet water system in surface-induced deep hypothermia.

To shorten the time of cooling and rewarming in surface-induced deep hypothermia, we devised a jet water system for hypothermia which was constructed within the water bath of the operating-table. In the clinical applications for open heart surgery under surface-induced deep hypothermia, we found that the time required for cooling and rewarming, particularly the later, was significantly reduced without any adverse effects.

Adolescent↗
PubMed1989

Rewarming following hypothermic cardiopulmonary bypass in the malignant hyperthermia-susceptible patient: implications for diagnosis and perioperative management.

A 55-year-old, malignant hyperthermia-susceptible patient underwent myocardial revascularization without incident. Six hours postoperatively, he developed what was initially diagnosed as an MH crisis, for which he received intravenous dantrolene. The resultant muscle weakness prolonged the duration of postoperative mechanical ventilation and likely contributed to the development of a postoperative pneumonia. Plasma dantrolene levels were measured for the first 48 hours postoperatively and correlated with clinical findings. On reviewing the patient's perioperative course, it was felt that the hypermetabolic state was not due to MH. The patient's pattern of rewarming following hypothermic cardiopulmonary bypass was similar to non-MH-susceptible patients. Because of the difficulty in diagnosing a MH crisis after hypothermic bypass, it is recommended that patients receive prophylactic dantrolene preoperatively and after bypass. Nondepolarizing muscle relaxants should be given postoperatively to prevent shivering and respiratory acidosis while patients rewarm.

Cardiopulmonary Bypass↗