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PubMedDate not supplied

S100B blood levels correlate with rewarming time and cerebral Doppler in pediatric open heart surgery.

BACKGROUND: Brain hyperthermia, accompanying the rewarming phase of cardiopulmonary bypass (CPB), has been involved in the genesis of postoperative brain damage. Blood S100B levels are emerging as a marker of brain distress, and could offer a reliable monitoring tool at different times during and after open heart surgery. METHODS: Thirty-two patients undergoing repair of congenital heart disease with CPB and deep hypothermic circulatory arrest (DHCA) were monitored by S100B blood levels and middle cerebral artery Doppler velocimetry pulsatility index (MCA PI) before, during, and after surgical procedure at five predetermined time-points. RESULTS: Both S100B and MCA PI significantly increased, MCA PI values exhibiting a peak at the end of surgery time-point (p > 0.05), while S100B blood levels were increased at the end of CPB (p < 0.05). Multivariate analysis, with S100B levels measured at the end of CPB as dependent variable, showed a positive significant correlation with MCA PI (p = 0.04), with the CPB and the rewarming duration (p = 0.03 and p = 0.009, respectively). CONCLUSIONS: The present results show a significant correlation between a biochemical marker of brain damage and an index of increased cerebrovascular resistance, with higher levels during the rewarming CPB phase in pediatric open heart surgery.

Blood Volume↗
PubMed1997

Back from the dead: extracorporeal rewarming of severe accidental hypothermia victims in accident and emergency.

Severe accidental hypothermia in an urban environment is usually associated with drug or alcohol abuse or serious illness in elderly or debilitated patients. In the presence of cardiovascular instability, extracorporeal rewarming by cardiopulmonary bypass is the gold standard of treatment of such patients. Three cases of profound hypothermia with circulatory collapse are presented. Each was successfully resuscitated to a full neurological recovery using this method in an accident and emergency (A&E) department, although one died later of respiratory complications. All three cases had a serum potassium in the normal range at the start of treatment. Where facilities exist, extracorporeal rewarming can be performed in A&E for patients with profound hypothermia and circulatory collapse. Cardiopulmonary resuscitation must be continued throughout the rewarming process.

Alcoholism↗
PubMed1997

Inhibition of shivering increases core temperature afterdrop and attenuates rewarming in hypothermic humans.

During severe hypothermia, shivering is absent. To simulate severe hypothermia, shivering in eight mildly hypothermic subjects was inhibited with meperidine (1.5 mg/kg). Subjects were cooled twice (meperidine and control trials) in 8 degrees C water to a core temperature of 35.9 +/- 0.5 (SD) degrees C, dried, and then placed in sleeping bags. Meperidine caused a 3.2-fold increase in core temperature afterdrop (1.1 +/- 0.6 vs. 0.4 +/- 0.2 degree C), a 4.3-fold increase in afterdrop duration (89.4 +/- 31.4 vs. 20.9 +/- 5.7 min), and a 37% decrease in rewarming rate (1.2 +/- 0.5 vs. 1.9 +/- 0.9 degrees C/h). Meperidine inhibited overt shivering. Oxygen consumption, minute ventilation, and heart rate decreased after meperidine injection but subsequently returned toward preinjection values after 45 min postimmersion. This was likely due to the increased thermoregulatory drive with the greater afterdrop and the short half-life of meperidine. These results demonstrate the effectiveness of shivering heat production in attenuating the postcooling afterdrop of core temperature and potentiating core rewarming. The meperidine protocol may be valuable for comparing the efficacy of various hypothermia rewarming methods in the absence of shivering.

Adult↗
PubMed2003

Rewarming index of the lower leg assessed by infrared thermography in adolescents with type 1 diabetes mellitus.

The aim of this study was to determine whether infrared thermography before and after challenge of the lower leg in cold water may be a useful tool to detect abnormalities in skin blood flow in adolescent asymptomatic patients with type 1 diabetes mellitus (DM1) and to assess the optimal setting of skin temperature measurements. Twenty-five adolescents (10 female, 15 male, mean age 21.2 +/- 6.2 years, body mass index [BMI] 23.0 +/- 2.1 kg/m2) with a duration of DMI of 13.8 +/- 5.4 years and mean HbA1c levels 8.5 +/- 1.3% were compared to age- and sex-matched controls (BMI 22.9 +/- 2.2 kg/m2). Seven defined sites of the lower leg were assessed by infrared thermography before and for 10 min after exposure of the leg to 14 degrees C cold water. As skin temperature before exposure to cold water differs from individual to individual and basal temperature was significantly warmer in patients at the tip of the first (p < 0.05) and fifth (p < 0.05) toe, the rewarming index was calculated in order to compare data. Rewarming indexes of skin temperature during the whole measurement procedure (0-10 min) were significantly lower at the tip of the first (p < 0.05) and fifth (p < 0.01) toes and from minute 2-10 also at the inner ankle (p < 0.05) in patients compared to healthy controls. Rewarming indexes of the other four sites were not significantly different between patients and controls. Infrared thermography of the lower leg after cold water exposure is an easily applicable method and a useful tool to detect abnormalities of skin blood flow in adolescents with DM1 especially at the tips of the first and fifth toes and the inner ankle.

Adolescent↗
PubMed2000

[Rewarming of patients with accidental hypothermia with the help of heart-lung machine].

BACKGROUND: Different techniques have been used for treatment of victims with accidental hypothermia. We have used cardiopulmonary bypass (CPB) for rewarming hypothermic patients with circulatory failure or cardiac arrest. This report summarises our experiences with this patient group. MATERIAL AND METHODS: 23 patients, submersions (n = 15), avalanche (n = 1) and primary hypothermia (immersion/air cooling) (n = 7), were rewarmed using extracorporeal circulation with standard equipment for open-heart surgery. RESULTS: On a clinical basis, two patient populations could be identified; one group for whom asphyxia was probably present prior to and during cooling, and another group for whom asphyxia was unlikely. In the first group, one of 13 patients survived compared to the latter group where six out of ten survived. A search for laboratory and other variables that with certainty could contribute to the prediction of prognosis was unsuccessful. INTERPRETATION: Due to lack of safe prognostic predictors, all accidental hypothermic victims with circulatory failure should be rewarmed by cardiopulmonary bypass before further therapeutic decisions are made.

Accidents↗
PubMedDate not supplied

Cryopreservation of garlic shoot tips by vitrification: effects of dehydration, rewarming, unloading and regrowth conditions.

This paper investigates the effect of dehydration, rewarming, unloading and regrowth conditions and of bulb post-harvest storage duration on survival and regeneration of cryopreserved garlic shoot tips. PVS3 was the most effective of the seven vitrification solutions compared. Treating shoot tips with PVS3 for 150-180 min ensured 92 % regeneration after freezing. An air-drying treatment, performed either before or after the PVS3 treatment, was detrimental to regeneration of cryopreserved shoot tips. Rapid rewarming in a water-bath at 37 degree C gave higher regeneration than the slower rewarming procedures employed. Regeneration was similar using either sucrose or sorbitol unloading solutions. The growth regulator content of the recovery medium did not influence percentage regeneration. However, the fresh weight of explants cultured on medium containing 0.3 mg/L zeatin and 0.3 mg/L gibberellic acid was significantly higher than on other media. Post-harvest storage duration of bulbs dramatically influenced survival and regeneration of non-cryopreserved and cryopreserved shoot tips, which were nil for samples cryopreserved immediately after harvest and highest after 3 and 6 months of storage. The optimized cryopreservation protocol was applied to ten different garlic varieties, with regeneration percentages ranging between 72 and 95 %.

Cell Survival↗
PubMed2005

The impact of slow rewarming on inotropy, tissue metabolism, and "after drop" of body temperature in pediatric patients.

Pediatric patients undergoing surgical correction of congenital heart diseases using cardiopulmonary bypass (CPB) are subjected to hypothermia. Core temperature is cooled down to 26-28 degrees C during CPB. Postoperative hypothermia in these patients remains a source of long-intensive care unit (ICU) stay. Therefore, this study was performed to build a rewarming strategy aiming to improve the cardiac performance, minimize the early after-drop in both core and foot temperatures, and to achieve early achievement of homeostasis. Thirty pediatric patients of acyanotic congenital heart diseases were randomly allocated into one of three equal groups of 10. Group I was kept at 3 degrees C between nasopharyngeal and heater-cooler unit water temperatures during rewarming whereas group II and group III were kept at 5 degrees C and 7 degrees C, respectively. The following parameters were measured: 1) cardiac performance (cardiac index and peak velocity); 2) cumulative amrinone consumption, blood lactate levels, and total body oxygen consumption; 3) intraoperative and postoperative peak and trough core and foot temperatures; and 4) time to extubation and ICU stay. Group I patients showed statistically significant increase in cardiac index and peak velocity compared with groups II and III, at p < 0.05 and p < 0.025, respectively. Statistically, the consumption of amrinone was significantly decreased in group I compared with groups II and III, with p < 0.005 and p < 0.0005, respectively, at 6 hours postoperatively. Group I showed an insignificant increase in blood lactate level, where groups II and III showed significant increases compared with controls (p < 0.001 at 6 hours postoperatively). Intraoperatively, both trough core and peak foot temperatures of group I patients statistically were significantly higher than in group III patients at p < 0.0005 and p < 0.05, respectively. The same applies in the ICU as regards to the time to core temperature (p < 0.005) and the rate of foot warming (p < 0.01). It was found that a difference of 3 degrees C (group I) between nasopharyngeal and heater-cooler unit water temperatures during rewarming demonstrated the best outcome compared with 5 degrees C and 7 degrees C differences (groups II and III, respectively). This outcome was obvious in the following parameters: 1) the best cardiac performance (cardiac index and peak velocity); 2) the lowest values of cumulative amrinone consumption and blood lactate level; 3) the least after-drop in both core and foot temperatures; and 4) achievement of early homeostasis, shortest ICU stays, and conservation of the ICU resources.

Cardiopulmonary Bypass↗
PubMedDate not supplied

[Severe accidental hypothermia: rewarming by total cardiopulmonary bypass].

We present a case of a 20-year-old male with a history of habitual drug use who suffered extreme hypothermia (26 degrees C) after several hours' accidental exposure to low ambient temperature. The patient presented in deep coma with recurring ventricular fibrillation that yielded to electrical defibrillation once a central temperature of 27.4 degrees C was reached through internal rewarming with intravenous liquids and gastric lavage with warm water. Because this method was slow, we decided to continue rewarming with extracorporeal circulation through cannulation of the femoral vein and artery. The patient recovered consciousness after three hours, with no neurological secuelae. Emergency room staff have available the means for recognizing hypothermia and a protocol for its management. Extracorporeal circulation is an effective method for internal rewarming and must be used when the patient requires cardiopulmonary resuscitation or presents signs of severe hemodynamic instability.

Adult↗
PubMedDate not supplied

Rewarming cardiac surgery patients: radiant heat versus forced warm air.

This study compared time required to rewarm, incidence of shivering, and nurses' preferences in hypothermic postoperative cardiac surgery patients treated with a forced air warmer (Bair Hugger) or a noninfrared radiant heater (Thermal Ceiling). Data were collected on 38 subjects and 6 nonsubjects treated with warm blankets. Average minutes to rewarm were: forced air, 100.3; radiant heat, 99.3; and warm blankets, 188.2. The warm air subjects had significantly higher skin temperatures, lower incidence of shivering, and less severe afterdrop, suggesting that rewarming in these patients resulted from heat gained from the environment. Nurses preferred the forced air warmer to the noninfrared radiant heater.

Adult↗
PubMed1996

Rewarming: comparison of contemporary heat-exchangers.

Heat exchange methods must be efficient in order to minimize the patient's pump time. However, comparisons of heat exchangers have been rare. Therefore, the in vivo functions of the most popular, currently available heat exchangers, Sarns, Cobe, Medtronics Maxima, and an experimental model manufactured by Haemonetics were compared. Thirty-two pigs weighing between 63-74 kg were placed on cardiopulmonary bypass with right atrial and ascending aorta cannulation through a right thoracotomy. Thermocouples were placed in the pump tubing before and after the heat exchangers, in the water line before and after the heat exchangers, in the inlet and outlet line of the pump, and the esophagus, brain, bladder, rectum, liver, myocardium, and tympanic membranes of the pigs. They were cooled until the bladder temperature was reduced to 14 degrees C, and maintained at that temperature for 10 minutes. Rewarming was begun until the bladder temperature became 37 degrees C. The pump flow was maintained between 50-60 ml/kg/min with standard ventilation. Cobe, Sarns, Maxima, and Haemonetics heat exchangers were tested and their function determined by comparing the time necessary for rewarming. The Haemonetics heat exchanger required a significant shorter time than the others to rewarm the pigs to normal bladder temperature (Cobe 82.0 +/- 12.0, Sarns 80.3 +/- 15.4, Maxima 89.0 +/- 13.9 Haemonetics 68.7 +/- 13.4, p < 0.05). The principal advantage was seen at the lowest temperatures between the Haemonetics experimental heat exchanger and the other heat exchangers. No statistically significant superiority was seen at higher temperatures. The current heat exchangers are relatively comparable but improved performance is possible with available technology.

Animals↗
PubMed1997

Effects of surface-induced hypothermia and rewarming on canine cardiac contraction-relaxation cycle.

The aims of this study were to elucidate the effects of cooling and rewarming on cardiac contraction-relaxation cycle. Cardiac catheterization was carried out on eleven anaesthetized beagle dogs. The dogs were cooled between icebags until the temperature of the blood in the ascending aorta was 25 degrees C and then rewarmed. Heart rate increased transiently at the beginning of cooling down to 33 degrees C (P < 0.05). Cardiac output first tended to increase until a body temperature of 33 degrees C was achieved but then decreased (P < 0.05). The systolic period lengthened significantly (P < 0.001) when the body temperature decreased from 37 degrees C to 25 degrees C. Cardiac relaxation slowed down linearly with temperature during cooling. The peak value of the first order derivative of the ventricular pressure curve (dP/dtmax) increased at the beginning of cooling down to 33 degrees C, indicating enhanced systolic pressure rise in left ventricle but returned to baseline values at lower temperatures. However the ejection fraction, systolic period and the systemic vascular resistance increased at the temperatures below 33 degrees C despite the unaltered peak dP/dt and thus we conclude that the contraction force is augmented in the hypothermia. All the parameters measured recovered to normal during rewarming and no signs of heart failure were noted during the experiments.

Animals↗
PubMed1997

[Three patients with accidental hypothermia: customized rewarming].

Three patients, two men aged 47 and 33 years and a woman aged 33 years, became hypothermic after an accident with body temperatures of 34.5, 26.2 and 23.1 degrees C, respectively. Two of them developed circulatory disorders, for which reanimation was performed. All three patients recovered after active external heating using among other things warmed infusion fluids, a warmed waterbed, continuous arteriovenous rewarming and rewarming with the heart-lung machine. For the treatment to be successful, the type of rewarming selected should be guided by the degree of hypothermia, the circulatory situation and the severity of the accessory injuries.

Accidents, Traffic↗
PubMed1996

Changes in liver core temperature during preservation and rewarming in human and porcine liver allografts.

Liver core temperature during organ procurement, storage, and rewarming has not been reported in human orthotopic liver transplantations (OLT). We have shown in the rat that optimal temperature for liver storage is not 4 degrees C but 0 degree C to 1 degree C. Therefore, a study was undertaken in humans and in pigs to determine the pattern of temperature change during OLT. The porcine studies were performed, because it was not possible to follow human grafts during the period that they were sterilely packaged. Temperature depression in humans was rapid during organ perfusion, remained stable during organ dissection, and decreased again slightly, when after excision, the organ was perfused again. Temperature depression during the period of perfusion with University of Wisconsin (UW) solution was curvilinear with the initial rapid temperature depression followed by a period of slower temperature depression. Volume perfused versus time was linear during these periods and the relationship between temperature depression and volume infused was curvilinear. At the time of packaging, 65 +/- 12 minutes after start of cold perfusion, the liver core temperature was 5.7 degrees C +/- 1.3 degrees C. Studies in the pig showed that it took 75 to 100 minutes for liver core temperature to decrease below 5 degrees C, and core temperature reached a plateau at 1 degree C at 195 +/- 75 minutes after packaging. During the rewarming period in humans, while vascular anastomoses were being constructed, there was a rapid linear increase in temperature from 0.8 degree C, when the graft was removed from the cold, to 17.2 degrees C +/- 3.1 degrees C at 45.5 +/- 4.4 minutes later, just before portal reperfusion commenced. These studies show that it takes only a short time to cool livers down to 10 degrees C, but after flushing is stopped, temperature depression is markedly reduced, and ideal temperatures are not reached before packaging. Rewarming of livers during performance of vascular anastomoses is rapid and reaches temperatures at which substantial hepatic metabolism is occurring.

Animals↗
PubMed1998

Cooling and rewarming-induced IL-8 expression in human bronchial epithelial cells through p38 MAP kinase-dependent pathway.

p38 mitogen-activated protein kinase (MAP) kinase is activated by various stresses; however, little is known about cold stress which has been shown to cause various inflammatory diseases. In the present study, we examined the effect of cold stimulation on interleukin-8 (IL-8) expression and a role of p38 MAP kinase in IL-8 expression in human bronchial epithelial cells (BEC) in order to clarify the mechanism in hypothermic temperature-induced inflammation. The results showed that cold stimulation induced tyrosine phosphorylation of p38 MAP kinase but not IL-8 expression. IL-8 expression in BEC was induce when the temperature of incubation changed from 1 degree C to 37 degrees C (cooling and rewarming). The specific p38 MAP kinase inhibitor SB 203580 inhibited cooling and rewarming-induced IL-8 expression, indicating that cooling and rewarming-induced IL-8 expression in BEC was mediated through p38 MAP kinase-dependent pathway.

Bronchi↗
PubMed2001

Glutathione synthesis during the rewarming of rat hepatocytes preserved in the University of Wisconsin solution.

In this study, we used isolated rat hepatocytes to investigate the effect of nucleoside content of the preserved cells on the ability to synthesize glutathione (GSH) during the rewarming process. We cold-stored hepatocytes in University of Wisconsin (UW) solution (72 h, 0 degrees C, N(2)) without nucleosides and with the addition of 5 mM adenosine or 10 mM ATP. After 72 h of cold storage, we determined the GSH synthesis rate and the ATP content of the cells. We found a GSH synthesis rate similar to that of freshly isolated hepatocytes only in the group of cells cold-stored with 10 mM ATP. When we tested the cellular ATP concentrations, we found that controls and preserved cells with 10 mM ATP showed a similar value of ATP during the rewarming step. Our results suggested that the incorporation of ATP in the UW solution increased the ATP content and the rate of GSH synthesis of cold-stored hepatocytes during rewarming.

Adenosine↗
PubMed1993

Heat storage and body temperature during cooling and rewarming.

During calorimetric experiments with forced cooling and rewarming, changes in rectal temperature (Tre) and mean skin temperature (Tsk) allowed calculations of Burton's (1935) weighting coefficient "a", which relates body temperature change to change in mean body temperature (delta Tb). Calculating delta Tb from change in body heat content (delta Hb), which was determined from direct and indirect calorimetry, included individualized values for body specific heat based on body fat content. In five different cooling procedures there were two with cooling by exposure to cold water and three with cooling in a tubing suit; two of the procedures included mild exercise. The delta Hb ranged from -335 to -1600 kJ; rewarming restored body heat content. The mean (SEM) value of "a" in 119 determinations was 0.75 (0.01). This small variability in the coefficient probably came from the large values of delta Hb and from the use of maximal changes in Tsk and Tre, including afterdrop. Change in Tre by itself correlated with delta Tb, but with much variability. In forced body cooling and rewarming, 0.75 (delta Tre) + 0.25 (delta Tsk) gives an accurate estimate of delta Tb, hence change in body heat storage.

Adult↗
PubMed1990

Accidental hypothermia with cardiac arrest: complete recovery after prolonged resuscitation and rewarming by extracorporeal circulation.

A 51-year-old male remained immersed in sea water (6 degrees C) for 40 min. Brought ashore, the ECG showed asystole. Advanced life support was immediately commenced. On arrival in hospital his rectal temperature was 27 degrees C, but continued to fall to 24 degrees C. The ECG remained isoelectric. Cardiopulmonary resuscitation was continued until extracorporeal circulation was established 190 min after rescue. Upon rewarming ventricular fibrillation occurred which was converted to sinus rhythm with a bolus of lignocaine followed by D.C. conversion at 31.5 degrees C. When rewarming was complete after 60 min, signs of severe heart failure became evident. Sternotomy and pericardiotomy were performed to exclude cardiac tamponade. After 60 min of re-perfusion the patient was be weaned from bypass supported by a high-dose vasopressor infusion and nitroglycerine. He was discharged after 13 days with no evidence of any permanent organ damage. Given the advantage of providing circulatory support, extracorporeal circulation may be useful when rewarming hypothermic victims with cardiac arrest.

Extracorporeal Circulation↗
PubMed2001

Protection of the rat liver against rewarming ischemic injury by University of Wisconsin solution.

BACKGROUND/AIM: University of Wisconsin (UW) solution has been proven able to prevent liver injury during cold ischemia. During rewarming ischemia, however, the efficacy of this solution in preserving hepatocyte function is unclear. The aim of the present study was to investigate to what extent UW solution protects rat liver during rewarming ischemia. METHODS: Livers were washed out with cool physiologic saline or with UW solution and subjected to rewarming ischemia for periods of 20 min or 45 min followed by reperfusion using a blood-free perfusion model. RESULTS: In comparison with controls, ischemia for 20 min in saline-treated livers led to mild depression of hepatocyte function, while UW solution afforded complete protection of the liver. In UW-treated livers, compared with saline-treated livers exposed to ischemia for 45 min, portal flow was slightly but significantly higher, bile production was increased by 62%, and lactate dehydrogenase leakage into the perfusate was reduced by 61%. In an attempt to explain mechanisms of liver protection by UW solution, we found that UW solution inhibited conversion of hypoxanthine into uric acid, but this effect was not associated with decreased degradation of adenine nucleotides in the liver during ischemia. Following 30 min reperfusion, UW solution increased tissue levels of adenosine triphosphate (not significantly) and adenosine diphosphate (significantly). Further, UW solution markedly reduced tumor necrosis factor-alpha release by the liver both after ischemia and after reperfusion. CONCLUSIONS: These results create the hypothesis that UW solution may protect liver tissue during ischemia in liver surgery as well as during the implantation stage of liver transplantation.

Adenosine↗