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PubMed1999

Accidental hypothermia.

Individuals at extremes of age and those who have certain underlying medical conditions are at greatest risk for hypothermia. Hypothermia may occur during any season of the year and in any climate. Prompt recognition of hypothermia and early institution of the rewarming techniques are imperative for a successful outcome with minimal complications. Several rewarming techniques are available and the decision to use any of them depends on the degree of hypothermia, the condition of the patient, and the rewarming rate possible with the technique chosen.

Electrocardiography↗
PubMed1994

[Severe accidental hypothermia].

Two cases of severe accidental hypothermia (core temperature below 25 degrees C) are reported. Both occurred in an urban area during the same winter period. Both patients had the same age and similar clinical symptoms. In the first patient, the EEG, the echocardiography and the blood gases were in favour of a good tolerance of hypothermia, which led to choice a non aggressive rewarming method. The latter included the rewarming of inhaled gas mixture as well as i.v. fluids and gastro-intestinal lavage fluid. The outcome was uneventful. In the second patient, the visceral and biological consequences were more important (pH: 6.80, blood glucose concentration: 1.48 mmol.L-1, major coagulation disorders). Therefore a rapid rewarming via a cardiopulmonary bypass was preferred. The patient died from a prolonged shock with disseminated intravascular coagulation. The use of cardiopulmonary bypass which is essential in case of cardiac arrest rhythm, is controversial in case of severe hypothermia with a still beating heart.

Acidosis↗
PubMed1999

Effects of phentolamine on tissue perfusion in pediatric cardiac surgery.

OBJECTIVE: To evaluate whether the deleterious effects of cardiopulmonary bypass (CPB) can be overcome by phentolamine-induced pharmacologic vasodilation in pediatric patients with congenital heart disease. DESIGN: Prospective, randomized, clinical study. SETTING: Single university hospital. PARTICIPANTS: Forty-three pediatric patients undergoing open cardiac surgery for repair of congenital heart disease. INTERVENTIONS: Patients were randomly allocated into two groups. Patients in group 1 (n = 22) received 0.2 mg/kg of phentolamine during the cooling and rewarming periods of CPB. Group 2 patients (n = 21) did not receive phentolamine. Temperature measurements (rectal [R], nasopharyngeal [N], and toe [P]) and serum lactate values were obtained before, during, and after CPB; systemic oxygen consumption was evaluated during CPB. MEASUREMENTS AND MAIN RESULTS: At the end of the CPB period and at the end of the operation, lactate values of group 1 (1.87+/-0.37 and 1.8+/-0.39 mmol/L, respectively) were significantly lower than values of group 2 (2.24+/-0.28 and 2.33+/-0.33 mmol/L; p < 0.05 and p < 0.05, respectively). At the beginning of the rewarming period N-R temperature gradients of group 1 (0.14 degrees C+/-0.92 degrees C) were lower than group 2 (-0.58 degrees C+/-1.84 degrees C) values (p < 0.05). Central-peripheral temperature gradients of group 1 obtained at the end of the CPB period (N-R = 2.18 degrees C+/-0.69 degrees C; N-P = 7.84 degrees C+/-1.54 degrees C; R-P = 5.66 degrees C+/-1.70 degrees C) were significantly lower than the values of group 2 (N-R = 2.80 degrees C+/-0.91 degrees C, N-P = 9.97 degrees C+/-2.02 degrees C; R-P = 7.18 degrees C+/-2.10 degrees C; p < 0.05; p < 0.001; p < 0.05). At the end of the operation values of group 1 (N-R = 0.48 degrees C+/-0.31 degrees C; N-P = 6.30 degrees C+/-1.23 degrees C; R-P = 5.82 degrees C+/-1.16 degrees C) were significantly lower than the values of group 2 (N-R = 0.94 degrees C+/-0.56 degrees C; N-P = 8.69 degrees C+/-0.28 degrees C; R-P = 7.75 degrees C+/-2.15 degrees C; p < 0.05; p < 0.001; p < 0.001). The systemic oxygen consumption values of group 1 were higher than group 2 (6.26+/-1.82 v 5.17+/-1.05 mL/min/kg; p < 0.05) after complete rewarming. Mean arterial pressure (MAP) values of group 1 (58.9+/-6.4 mmHg) were lower than group 2 (63.4+/-6.7 mmHg) at the period after CPB (p = 0.03). CONCLUSION: The results suggest that the use of phentolamine during CPB is associated with limited systemic anaerobic metabolism and more uniform body perfusion.

Adrenergic alpha-Agonists↗
PubMed2003

Cardiopulmonary resuscitation after near drowning and hypothermia: restoration of spontaneous circulation after vasopressin.

Recent animal data have challenged the common clinical practice to avoid vasopressor drugs during hypothermic cardiopulmonary resuscitation (CPR) when core temperature is below 30 degrees C. In this report, we describe the case of a 19-year-old-female patient with prolonged, hypothermic, out-of-hospital cardiopulmonary arrest after near drowning (core temperature, 27 degrees C) in whom cardiocirculatory arrest persisted despite 2 mg of intravenous epinephrine; but, immediate return of spontaneous circulation occurred after a single dose (40 IU) of intravenous vasopressin. The patient was subsequently admitted to a hospital with stable haemodynamics, and was successfully rewarmed with convective rewarming, but died of multiorgan failure 15 h later. To the best of our knowledge, this is the first report about the use of vasopressin during hypothermic CPR in humans. This case report adds to the growing evidence that vasopressors may be useful to restore spontaneous circulation in hypothermic cardiac arrest patients prior to rewarming, thus avoiding prolonged mechanical CPR efforts, or usage of extracorporeal circulation. It may also support previous experience that the combination of both epinephrine and vasopressin may be necessary to achieve the vasopressor response needed for restoration of spontaneous circulation, especially after asphyxial cardiac arrest or during prolonged CPR efforts.

Adult↗
PubMed2000

Hypothermia injury/cold-induced apoptosis--evidence of an increase in chelatable iron causing oxidative injury in spite of low O2-/H2O2 formation.

When incubated at 4 degrees C, cultured rat hepatocytes or liver endothelial cells exhibit pronounced injury and, during earlier rewarming, marked apoptosis. Both processes are mediated by reactive oxygen species, and marked protective effects of iron chelators as well as the protection provided by various other antioxidants suggest that hydroxyl radicals, formed by classical Fenton chemistry, are involved. However, when we measured the Fenton chemistry educt hydrogen peroxide and its precursor, the superoxide anion radical, formation of both had markedly decreased and steady-state levels of hydrogen peroxide did not alter during cold incubation of either liver endothelial cells or hepatocytes. Similarly, there was no evidence of an increase in O2-/H2O2 release contributing to cold-induced apoptosis occurring on rewarming. In contrast to the release/level of O2- and H2O2, cellular homeostasis of the transition metal iron is likely to play a key role during cold incubation of cultured hepatocytes: the hepatocellular pool of chelatable iron, measured on a single-cell level using laser scanning microscopy and the fluorescent indicator phen green, increased from 3.1 +/- 2.3 microM (before cold incubation) to 7.7 +/- 2.4 microM within 90 min after initiation of cold incubation. This increase in the cellular chelatable iron pool was reversible on rewarming after short periods of cold incubation. The cold-induced increase in the hepatocellular chelatable iron pool was confirmed using the calcein method. These data suggest that free radical-mediated hypothermia injury/cold-induced apoptosis is primarily evoked by alterations in the cellular iron homeostasis/a rapid increase in the cellular chelatable iron pool and not by increased formation of O2-/H2O2.

Animals↗
PubMed1999

The effects of prostaglandin E1 on intraoperative temperature changes and the incidence of postoperative shivering during deliberate mild hypothermia for neurosurgical procedures.

UNLABELLED: We investigated the effects of i.v. prostaglandin E1 (PGE1) on intraoperative changes of core temperature and the incidence of postoperative shivering in neurosurgical patients undergoing deliberate mild hypothermia. Eighty-three patients were randomly assigned to one of three groups: patients in the control group did not receive PGE1, whereas patients in the PG20 group and PG50 group received PGE1 at a dose of 0.02 and 0.05 microg x kg(-1) x min(-1), respectively. The administration of PGE1 was started just after the induction of anesthesia and continued until the end of anesthesia. Anesthesia was maintained with nitrous oxide in oxygen, sevoflurane, and fentanyl. After the induction of anesthesia, patients were cooled using a water blanket and a convective device blanket. Tympanic membrane temperature was maintained at 34.5 degrees C. During surgical wound closure, patients were rewarmed. Intraoperative changes in tympanic membrane and skin temperatures and the incidence of postoperative shivering were compared among groups. Demographic and intraoperative variables were similar among groups. There were no significant differences in tympanic temperatures among groups at each point during the operation. Skin temperature 30 min after rewarming and just after tracheal extubation was significantly lower in the PG20 group than in the PG50 group. Postoperative shivering was more frequent in the PG20 group (43%) than in the control (13%) and PG50 (17%) groups. These results suggest that the intraoperative administration of PGE1 does not affect changes in core temperature during deliberate mild hypothermia and that PGE1 at a dose of 0.02 microg x kg(-1) x min(-1) may increase the occurrence of postoperative shivering. IMPLICATIONS: Deliberate mild hypothermia has been proposed as a means of providing cerebral protection during neurosurgical procedures. Vasodilating drugs may be used during deliberate mild hypothermia to maintain peripheral circulation and to enhance the cooling and rewarming rate. In the present study, however, we found no benefit from i.v. prostaglandin E1 administration during deliberate mild hypothermia in neurosurgical patients.

Alprostadil↗
PubMed1997

Cerebral oxygenation during warming after cardiopulmonary bypass.

OBJECTIVES: To evaluate jugular venous oxygen saturation (SjVO2), measured with a fiberoptic oximetry catheter, and brain tissue oxygen saturation, measured by near-infrared spectroscopy (NIRSO2), as monitors of cerebral oxygenation during cardiopulmonary bypass surgery. DESIGN: Prospective, clinical study. SETTING: Operating room of a Veterans Administration Hospital. PATIENTS: Nineteen patients undergoing moderate hypothermic cardiopulmonary bypass surgery. INTERVENTIONS: SjvO2 and NIRSO2 were monitored in the patients during the surgical procedure. MEASUREMENTS AND MAIN RESULTS: Moderate hypothermic cardiopulmonary bypass surgery had two distinct cerebral hemodynamic phases. While the patients were hypothermic, SjvO2 averaged 80 +/- 7% and none of the patients had an increase in cerebral lactate production. During the rewarming period, however, reductions in SjvO2 to < 50% occurred in 16 (84%) patients and increased cerebral anaerobic metabolism developed in 11 (58%) patients. SjvO2 during rewarming was dependent on mean arterial pressure, with 60 mm Hg appearing to be a critical value. Two other factors appeared to also contribute to the jugular desaturation, a low hematocrit and a rapid warming time. The SjvO2 catheter had excellent performance during the surgery. The average difference between paired measurements of SjvO2 by the catheter and in blood samples was -0.4 +/- 4.25%, and the correlation between the two measurements was highly significant (r2 = .93; p < .001). The NIRSO2 trended with the SjvO2 in most patients (r2 = .63; p < .001). CONCLUSIONS: The study confirms other studies showing that jugular venous desaturation can occur during rewarming after cardiopulmonary bypass surgery. Presently, SjvO2 appears to be a better monitor of cerebral oxygenation than NIRSO2. However, NIRSO2 has promise as a noninvasive monitor of cerebral oxygenation if future developments allow more quantitative measurements of oxygen saturation.

Aged↗
PubMedDate not supplied

Using evidence-based practice to develop a protocol for postoperative surgical intensive care unit patients.

Sixty adult postoperative patients from the surgical intensive care unit with core temperatures <35.4 degrees C, as measured by a pulmonary artery catheter, were randomly assigned to one of three treatment options for hypothermia. Results of this study confirmed findings in the literature that forced warm air generated quickest rewarming times. A rewarming protocol for hypothermic patients was developed and implemented. Performance improvement activity demonstrated high compliance rates with nurses using the rewarming protocol.

Aged↗
PubMed2001

Reversible temperature-sensitive alterations in lung fluid balance.

Hypothermia is intentionally imposed during the harvesting of lungs for transplantation. The aim of this study was to investigate the fluid balance alterations in rat lung preparations exposed to hypothermic perfusion. Lowering perfusate temperature from 37 degrees C to values between 27 and 7 degrees C caused an immediate, marked pulmonary hypertension and vasoconstriction accompanied by rapid development of pulmonary edema (+1.15 g, or approximately 90%, gain in lung weight within 5 min). However, on rewarming, vasoconstriction was immediately reversed. Edema was resolved, but along a two-component time course: an immediate reduction of lung weight on rewarming (t 1/2 of 0.5 min) that mirrored the recovery of pulmonary artery pressure and vasoconstriction, and also a slower pressure-independent component of recovery (t 1/2 of 3.5 min). Ouabain (300 microM) markedly inhibited the lung's ability to recover from edema, indicating that fluid clearance from lung tissue was the result of activation of ouabain-sensitive (Na+,K+)-ATPase pump. Results could not be explained by vascular or airspace injury as lung sections from hypothermic lungs appeared normal. The findings indicate that hypothermia induces pulmonary edema formation, which can be rapidly cleared upon rewarming by activation of ouabain-sensitive (Na+,K+)-ATPase pump. Thus, impaired fluid clearance from lung extravascular spaces may be a critical factor limiting gas exchange in transplanted lungs exposed to hypothermia.

Animals↗
PubMed2003

After spontaneous hypothermia during hemorrhagic shock, continuing mild hypothermia (34 degrees C) improves early but not late survival in rats.

BACKGROUND: Spontaneous hypothermia is common in victims of severe trauma. Laboratory studies have shown benefit of induced (therapeutic) mild hypothermia (34 degrees C) during hemorrhagic shock (HS). Clinical data, however, suggest that hypothermia, which often occurs spontaneously in trauma patients, is detrimental. Because critically ill trauma patients are usually cool, the clinical question, which has not been explored in the laboratory with long-term outcome, is whether maintaining hypothermia or actively rewarming the patient improves outcome. We hypothesized that after spontaneous cooling during HS, continuing mild therapeutic hypothermia during resuscitation is beneficial compared with active rewarming. METHODS: In study A, under light isoflurane anesthesia, 24 Sprague-Dawley rats were bled over 10 minutes to, and maintained at, mean arterial pressure (MAP) of 40 mm Hg until reuptake of 30% of maximal shed blood volume was needed. Rectal temperature (Tr) decreased spontaneously to, and was then maintained at, 35 degrees C during HS. Fluid resuscitation included the remaining shed blood and up to 400 mL/kg of lactated Ringer's solution with 5% dextrose over 4 hours. During resuscitation, three groups (n = 8 each) were studied: normothermia (rapid rewarming to Tr 37.5 degrees C at the beginning of resuscitation); hypothermia-2 h (cooling to Tr 34 degrees C to resuscitation time 2 hours); and hypothermia-12 h (cooling to Tr 34 degrees C to 12 hours). Rats were observed to 72 hours. In study B, more severe HS than in study A was studied. HS was induced with 3 mL/100 g blood withdrawal over 15 minutes followed by maintenance of MAP of 40 mm Hg until 50% of maximal shed blood volume was needed. Two groups (n = 8 each) were studied: normothermia and hypothermia-12 h. Data are presented as mean +/- SD or median (range). RESULTS: In study A, both hypothermia groups had higher MAP and lower heart rates during resuscitation than the normothermia group (p < 0.01). Survival to 72 hours was achieved in three of eight rats in the normothermia group and two of eight in each hypothermia group. Thirteen of 17 deaths occurred after 24 hours. In study B, for resuscitation, the hypothermia group needed less fluid (53 +/- 6 mL vs. 79 +/- 32 mL, p < 0.05), but had higher MAP (p < 0.01), lower heart rate (p < 0.01), and lower lactate level (p = 0.06). All rats died before 72 hours. The hypothermia group had longer survival time (24.5 [13-48.5] hours) than the normothermia group (7.5 [1.5-19] hours) (p = 0.003 by life table analysis). CONCLUSION: After spontaneous cooling during moderately severe HS, mild, controlled hypothermia during resuscitation does not seem to affect long-term survival. After more severe HS, hypothermia increases survival time. Hypothermia supports arterial pressure during resuscitation from severe HS.

Animals↗
PubMed2004

Comparison of pH-stat versus Alpha-stat during hypothermic cardiopulmonary bypass in the prevention and control of acidosis in cardiac surgery.

OBJECTIVES: To compare the effects of blood-gas management using either alpha-stat (temperature-uncorrected blood-gas management) or pH-stat (temperature-corrected blood-gas management) strategies, 30 patients undergoing coronary artery bypass surgery allocated randomly to either one of the approaches were studied. Acid-base balance, tissue oxygenation, and biochemical parameters were measured at distinct times: before bypass, after 15 min of hypothermia at 32 degrees C, after 45 min of hypothermia at 32 degrees C, after 15 min of rewarming at 37 degrees C, and 45 min after the end of bypass in normothermic conditions. RESULTS: The groups were similar with regard to physical characteristics, physiological parameters, and bypass time. In the pH-stat group, CO2 administered with the aim of correcting pH for the patients hypothermic temperature caused a significant increase in temperature-uncorrected PaCO2 and a decrease in arterial temperature-uncorrected pH at 45 min. During the rewarming period and following bypass, the pH was lower and PaCO2 higher in the pH-stat group (P < 0.001). CONCLUSION: It was found that during the rewarming period and following bypass, the resulting acidosis caused by the procedure was less in the alpha-stat group. It was found that there were no difference between the two groups, with regard to tissue perfusion, as is seen by the tissue oxygenation parameters and lactic acid concentration.

Acid-Base Equilibrium↗
PubMed1995

The management of temperature during cardiopulmonary bypass: effect on neuropsychological outcome.

Laboratory studies demonstrate that mild degrees of brain cooling (2 degrees C to 5 degrees C) confer substantial protection from ischemic brain injury, and that mild elevation of brain temperature can be markedly deleterious. During hypothermic cardiopulmonary bypass (CPB) patients are made hypothermic and then rewarmed at a time when they are exposed to neurological insults. Our studies show that during rewarming, peak brain temperatures near 39 degrees C often are achieved inadvertently. We hypothesize that maintaining brain temperature < or = 34 degrees C during and after CPB will reduce the incidence of postoperative neuropsychological deficits. We present safety data from a study of 30 patients assigned either to conventional hypothermic CPB with rewarming or a protocol where brain temperature is raised only to 34 degrees C at the time of separation from CPB. There was no difference in bleeding, cardiac morbidity, or time to extubation between groups. We designed a neuropsychological test battery to detect postoperative neuropsychological deficits and tested its usefulness in a preliminary sample of 15 patients undergoing hypothermic CPB. We found patient acceptability and compliance were good. Sensitivity also seemed adequate in that 30% of patients were identified as having deteriorated at 1 week postoperatively compared to preoperatively, a result similar to that reported by others. Clinical trials of the efficacy of mild hypothermia in modulating brain injury in humans are needed before techniques of CPB can be designed to optimize neuroprotection.

Aged↗
PubMed2006

Temperature during cardiopulmonary bypass: the discrepancies between monitored sites.

We performed studies in patients to determine whether temperature recordings from sites commonly monitored during hypothermic cardiopulmonary bypass adequately reflect cerebral temperature. In Study I (n = 12), temperatures monitored in the jugular bulb (JB) were compared with those recorded in the nasopharynx, esophagus, bladder, and rectum. In Study II (n = 30), temperature was also monitored in the arterial outlet of the membrane oxygenator. A calibrated recorder continuously and simultaneously recorded all temperatures. Study I found large temperature discrepancies between the JB and all other body sites during cooling and rewarming. There was considerable interindividual variability in the degree of discrepancy between the JB and other sites. Study II produced similar results but also showed that JB temperature reached equilibration with the temperature of blood entering the patient via the arterial outlet of the membrane oxygenator after cooling for 3.3 +/- 1.3 min and after rewarming for 16.5 +/- 5.5 min. Analysis of variance revealed that this arterial outlet site had the smallest average discrepancy of all temperature sites relative to the JB site (P < 0.001). In summary, temperatures measured in body sites over-estimated JB temperature during cooling and under-estimated it during rewarming, whereas arterial outlet blood temperature provided a good approximation.

Aged↗
PubMed2001

Severe accidental hypothermia treated in an ICU: prognosis and outcome.

STUDY OBJECTIVES: To assess the characteristics and outcomes of patients admitted to an ICU for severe accidental hypothermia, and to identify risk factors for mortality. METHODS: All consecutive patients admitted to an ICU between January 1, 1979, and July 31, 1998, with a temperature of < or = 32 degrees C were retrospectively analyzed. Rewarming was always conducted passively with survival blankets and conventional covers. Prognostic factors were studied by means of univariate analysis (Mann-Whitney U and chi(2) tests) and multivariate analysis (logistic regression). RESULTS: Forty-seven patients were enrolled (mean +/- SD age, 61.7 +/- 16 years). Five patients had a cardiac arrest before ICU admission. Patient characteristics at ICU admission were as follows: temperature, 28.8 +/- 2.5 degrees C; systolic BP, 85 +/- 23 mm Hg; heart rate, 60 +/- 24 beats/min; Glasgow Coma Scale, 10.4 +/- 3.7; and simplified acute physiology score (SAPS) II, 50.9 +/- 27. Mechanical ventilation was necessary in 23 cases, and 22 patients in shock received vasoactive drugs. The mean length of stay in the ICU was 6.7 +/- 9 days. Eighteen patients (38%) died, but ventricular arrhythmia was never the cause. Univariate analysis identified several prognostic factors (p < 0.05): age (57 +/- 16 years vs 69 +/- 14 years), systolic arterial BP (93 +/- 20 mm Hg vs 71 +/- 21 mm Hg), blood bicarbonate level (23.5 +/- 5.2 mmol/L vs 16.6 +/- 6.2 mmol/L), SAPS II score (35.3 +/- 19.5 vs 72 +/- 21), mechanical ventilation (34% vs 81%), vasopressor agents (42% vs 82%), rewarming time (11.5 +/- 7.2 h vs 17.2 +/- 7 h), and discovery of the patient at home (2.3% vs 54.5%). The initial temperature did not influence vital outcome (28.9 +/- 2.6 degrees C vs 28.6 +/- 2.2 degrees C). Only the use of vasoactive drugs (odds ratio, 9; 95% confidence interval, 1.6 to 50.1) was identified as a prognostic factor in the multivariate analysis. CONCLUSION: Severe accidental hypothermia is a rare cause of ICU admission in an urban area. Its mortality remains high, but there is no overmortality according to the SAPS II-derived prediction of death. Shock, requiring treatment with vasoactive drugs, is an independent risk factor for mortality, while initial core temperature is not. It remains to be determined whether aggressive rather than passive rewarming procedures are better.

Adult↗
PubMed2003

Treatment of term infants with head cooling and mild systemic hypothermia (35.0 degrees C and 34.5 degrees C) after perinatal asphyxia.

OBJECTIVE: To assess the safety of selective head cooling in birth-asphyxiated term newborn infants while maintaining the rectal temperature at 35.0 degrees C or 34.5 degrees C. METHODS: Twenty-six term infants with Apgar <or=6 at 5 minutes or cord/first arterial pH <7.1, plus evidence of encephalopathy, were studied. After parental consent had been obtained, 13 infants received selective head cooling with the rectal temperature maintained at 35.0 degrees C in 6 infants and at 34.5 degrees C in 7 infants. The remaining 13 infants were normothermic. Cooling was achieved by circulating water at 10 degrees C through a cap placed around the head. Rectal, fontanelle, and nasopharyngeal temperatures were monitored. RESULTS: One cooled infant died 2 days after rewarming, and 3 control infants died. Seizures occurred in 9 (69%)of 13 cooled infants and 5 (38%) of 13 control infants. Respiratory support within the first 72 hours of life was required in 10 of 13 infants in both the cooled and control groups. Three cooled infants and 1 control infant received nitric oxide for persistent pulmonary hypertension. During the same interval, 6 of the cooled infants and 4 of the control infants had episodes in which their blood pressure fell to <40 mm Hg; in 2 infants in each group, the lowest blood pressure was below 35 mm Hg. No requirement for volume expansion or increased inotropic support was seen in any infant during stepwise rewarming. All of the cooled infants demonstrated a fall in heart rate during cooling, but the rate was <80/min in only 2 cases and no infant had a rate <70/min. No infant demonstrated an abnormal rhythm or was clinically compromised by the change in heart rate. One infant cooled to a rectal temperature of 34.5 degrees C had a prolonged QT interval of 570 ms associated with a heart rate of 85/min on electrocardiogram aged 34 hours. This returned to normal after rewarming. Platelet counts below 150 x 10(9)/L, hypoglycemia below 2.6 mmol/L, and highest creatinine were not statistically different between cooled and control infants. Positive precooling blood cultures were found in 1 cooled and 1 control infant. The mean cap water input temperature used during cooling was 10 +/- 1 degrees C. During active cooling, the mean difference between rectal and nasopharyngeal temperature was 1.4 degrees C in the infants who were not receiving respiratory support, but this gradient could not be measured in those who were receiving respiratory support that involved delivery of warmed gases to the nasopharynx. CONCLUSIONS: This study suggests that selective head cooling combined with mild systemic hypothermia of 34.4 degrees C or 35.0 degrees C is a stable, well-tolerated method of reducing cerebral temperature in term newborn infants after perinatal asphyxia.

Anticonvulsants↗
PubMed2006

Hypothermia with profound anemia and pancreatitis.

A patient with severe hypothermia presented with an initial rectal temperature of 28.3 degrees C coupled with a hemoglobin of 2.2 g x dL(-1) and acute pancreatitis. Although hypothermia decreases oxygen and substrate consumption by tissues and can be cerebro-protective, the ideal rewarming strategy is unclear when the oxygen-delivery system is profoundly deficient, as with severe anemia. In this patient, truncal active external rewarming with a forced-air system, heated inhalation, and slow warmed transfusion yielded a 1.5 degrees C x h(-1) rate of rewarming and a good outcome. We discuss the numerous protective and detrimental factors affecting oxygenation and ventilation during hypothermia coupled with profound anemia and the possible etiologic explanations for coexistent hypothermia and pancreatitis.

Anemia↗
PubMedDate not supplied

Freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems.

The freeze-thawing behaviour of highly concentrated aqueous alkali chloride-glucose systems was investigated by differential scanning calorimetry (DSC). In the aqueous NaCl-glucose solution system, single or double glass transitions followed by the corresponding devitrification exotherms were observed during rewarming. In the aqueous KCl-glucose solution system, on the other hand, a single glass transition followed by an exotherm was observed during rewarming. The presence of double glass transitions observed for a certain composition of the aqueous NaCl-glucose solution was taken as an evidence for the liquid-liquid immiscibility at low temperatures. Two kinds of crystallisation accompanied by exotherms during rewarming were identified by X-ray diffraction as ice and ice/NaCl x 2H(2)O, or ice/KCl eutectic component.

Calorimetry, Differential Scanning↗
PubMed2002

[Accidental hypothermia--a challenge for rescue service and intensive care].

Accidental hypothermia is a rare clinical picture with different causes. Specific features are shown by patients who have accidents in water, due to rapid cooling. The SARRRAH project (Search and Rescue, Resuscitation and Rewarming in Accidental Hypothermia) was launched to secure fast and professional medical care right up to rewarming by extracorporal circulation. The University of Rostock takes part in this project. Based on the course of accidental hypothermia in fifteen patients, the authors report on the treatment of this life-threatening situation with special regard to the use of extracorporal circulation and present their first results. The core temperature of these patients lay between 16.0 and 34.0 degrees C. Eight of the patients had cardiac arrest at the scene of the accident. Seven of the patients with cardiac arrest were treated with extracorporal circulation in addition to cardiopulmonary resuscitation, which was started pre-clinically and continued in hospital. In one patient, extracorporal circulation was used at an initial temperature of 25.4 degrees C without previous cardiopulmonary resuscitation. Six of these fifteen patients with accidental hypothermia died. Five of the non-survivors belonged to the group of eight patients who were rewarmed by extracorporal circulation. With one exception, they also had the lowest core temperatures. Only a homogeneous and up-to-date documentation will allow further conclusions to be made for improving the concept of therapy.

Adolescent↗