We examined the hypothesis that mild hypothermia (rectal temperature 34 degrees C) results in the same survival time, whether induced spontaneously or intentionally, during untreated, lethal, uncontrolled hemorrhagic shock in rats. Sixty-four Sprague-Dawley male rats were randomly assigned to normothermia (Nth) (n=19), spontaneous mild hypothermia (Sp.Hth) (n=25) or controlled mild hypothermia (Con.Hth) (n=20) groups. After blood withdrawal of 3 mL/100 g over 15 minutes, followed by 75% tail amputation under spontaneous breathing and light anesthesia by i.p. injection of pentobarbital sodium, rats were observed without fluid resuscitation or hemostasis for 180 minutes or until death. The initial temperature of the Nth group was artificially maintained throughout the experiment. For the mild hypothermia groups, the Sp.Hth group was exposed to ambient temperature while the Con. Hth group was actively cooled to a target rectal temperature of 34 degrees C. In the Con.Hth group, all rats except one died before 180 minutes. All rats in the Nth group died within 38 minutes, and within 67 minutes in the Sp.Hth group. The average survival time was shortest in the Nth group at 20.3 +/- 5.3 minutes, followed by the Sp.Hth group at 30.1 +/- 13.5 minutes, and the Con.Hth group at 81.9 +/- 39.8 minutes (p 0.01). Tail bleed out volume was 0.51 +/- 0.19, 0.26 +/- 0.15 and 0.19 +/- 0.12 mL/100 g in the Nth, Sp.Hth and Con.Hth groups, respectively (p 0.05). In conclusion, spontaneous mild hypothermia did not prolong the survival time as much as controlled mild hypothermia in the rat model for untreated, lethal, uncontrolled hemorrhagic shock.
Animal ; Blood Pressure ; Body Temperature ; Hypothermia/*physiopathology ; *Hypothermia, Induced ; Male ; Rats ; Rats, Sprague-Dawley ; Shock, Hemorrhagic/*mortality/physiopathology/therapy

AIMTo investigate the effects of shivering on airway rewarming.

METHODSThe hypothermic dog model without shivering was established by immersing an anesthetized dog in cold water and administering atracurium to inhibit the dog shivering. The model dog respired warm fully humidified (40-45 degrees C, RH 99.9%) air and room temperature air(19 +/- 1 degrees C, RH 30% - 75%) to rewarm each for 2 hours, the priority of different temperature air respired was arranged randomly. After rewarming for 4 hours, the relaxed dog breathed warm humidified air by positive pressure ventilation in order to restore its spontaneous respiratory. Then the dog continued to respire warm humidified air spontaneously until the esophageal (Te) and rectal temperature (Tr) of the dog achieved the same degrees as the dog was immersed in the water. The metabolic heat production was detected by indirect calorimetry during the experiment.

RESULTS(1) When the shivering was inhibited, inhaling warm humidified air for 2 hours made the Tr and Te of the dogs increase 0.26-0.39 degrees C and 0.44-1.11 degrees C per hour respectively, inhaling air at room temperature for 2 hours made Tr and Te of the dogs decrease 0.24-0.51 degrees C and 0.58-0.67 degrees C per hour, respectively. And the changes in Tr and Te of the dogs were unrelated to the priority of inhaling air at different temperature. (2) When the dog with shivering respired spontaneously warm humidified air, the rewarming rates of Tr and Te were 2.26-2.33 degrees C/h and 1.96-2.38 degrees C/h respectively, quicker than those of the dogs whose shivering was inhibited. (3) Compared with metabolic heat production of the unshivering dog respiring warm humidified air by positive pressure ventilation, that of the shivering dog respiring warm humidified air spontaneously increased outstandingly, shivering thermogenesis made the rewarming rates increased obviously.

CONCLUSIONAirway rewarming is a method conducive to rewarming of hypothermia. When the body is shivering, the metabolic heat production increases obviously, that makes the rewarming rate increase markedly. So the shivering must be inhibited in order to eliminate the interference of shivering thermogenesis when the effects of airway rewarming are detected.

Animals ; Body Temperature Regulation ; Cold Temperature ; Dogs ; Hypothermia ; physiopathology ; therapy ; Hypothermia, Induced ; Male ; Respiratory Physiological Phenomena ; Shivering

Action Potentials ; Animals ; Electromyography ; Environmental Exposure ; Hypothermia ; Rats ; Rats, Wistar ; Seawater ; Thigh ; physiology ; physiopathology

OBJECTIVETo study the effect of selective moderate head cooling therapy on maximum length sequences brainstem auditory evoked potential (MLS-BAEP) in newborn piglets with hypoxic-ischemic brain damage.

METHODSSixteen newborn piglets aged 5-7 day old were randomly divided into three groups: normothermic control (n=4), HI (n=6) and mild hypothermia-treated (n=6). HI was induced through temporary occlusion of both carotid arteries, followed by mechanical ventilation with low concentration of oxygen (FiO2=0.06) for 30 minutes. Mild hypothermia was induced by equipment via circulating water. MLS-BAER was recorded before HI and at 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, 4 days, 7 days, 10 days, 13 days and 15 days after HI.

RESULTSCompared with the normothermic control group, all latencies and intervals tended to increase significantly at 72 hours in the HI group and reached peak values on day 7. From day 10, all latencies and intervals tended to decrease, but apart from wave I latency, still differed significantly from those of the normothermic control group. MLS-BAER variables did not reach normal values until day 15. Ⅲ latency, Ⅰ-Ⅲ interval and Ⅰ-Ⅴ interval were significantly reduced in the hypothermia-treated group between 60 and 7 days after HI compared with the HI group (P<0.05). V latency and Ⅲ-Ⅴ interval in the hypothermia-treated group were also reduced compared with the HI group between 72 hours and 7 days after HI (P<0.05).

CONCLUSIONSBoth peripheral and central auditory systems are disturbed by HI, which shows as a significant increase in MLS-BAER variables (all latencies and intervals) in newborn piglets. Involvement in central brainstem auditory system reaches a peak on day 7 after injury. MLS-BAER variables still cannot reach to normal values until day 15. Selective moderate head cooling therapy can significantly reduce brainstem damage induced by HI.

Animals ; Animals, Newborn ; Evoked Potentials, Auditory, Brain Stem ; Hypothermia, Induced ; Hypoxia, Brain ; physiopathology ; therapy ; Swine

Animals ; Female ; Gonads ; physiopathology ; Hypothermia ; chemically induced ; physiopathology ; Male ; Rats ; Rats, Wistar ; Sex Factors ; Soman ; adverse effects ; pharmacology

Animals ; Blood Pressure ; drug effects ; Chlorpyrifos ; toxicity ; Hypothermia ; chemically induced ; physiopathology ; Pesticides ; toxicity ; Rats ; Rats, Inbred LEC

Adolescent ; Adult ; Aged ; Body Temperature ; Craniocerebral Trauma ; physiopathology ; therapy ; Female ; Humans ; Hypothermia, Induced ; Male ; Middle Aged ; Treatment Outcome ; Young Adult

OBJECTIVETo study the effects of hypothermia on cardiac function in neonates after birth asphyxia.

METHODSFifty term newborns with Apgar score < 5 at 5 minutes were randomly divided into no cooling group (normothermia group, NG; rectal temperature = 36.5 degrees C +/- 0.5 degrees C, n = 27) and cooling group (hypothermia group, HG; rectal temperature = 34.5 degrees C +/- 0.3 degrees C, nasopharyngeal temperature = 34.0 degrees C +/- 0.5 degrees C, n = 23). The selective head cooling was applied to maintain nasopharyngeal temperature at 34 degrees C for 72 h in hypothermia group. Systolic and diastolic function was detected at the end of treatment by echocardiogram.

RESULTS(1) The heart rate was obviously decreased during the hypothermia treatment, and there was a significant difference between HG and NG [(103 +/- 15) bpm vs. (126 +/- 14) bpm, P < 0.05]. No cardiac arrhythmia and hypotension were found in all neonates. (2) There were no significant differences on the ejection fraction, stroke volume and cardiac output of left ventricle between the two groups (P > 0.05). No significant difference was found in the numbers of left and right ventricular diastolic dysfunction, pulmonary hypertension between the two groups (P > 0.05). (3) The level of cardiac troponin T (cTnT) in plasma was (0.47 +/- 0.15) ng/ml in HG, and (0.35 +/- 0.21) ng/ml in NG, and there was no significant difference between the two groups (P > 0.05).

CONCLUSIONNo significant cardiac dysfunction complication caused by the hypothermia treatment was found in term neonates after birth asphyxia.

Asphyxia Neonatorum ; physiopathology ; prevention & control ; Electrocardiography ; Heart ; physiopathology ; Heart Function Tests ; Humans ; Hypothermia, Induced ; methods ; Infant, Newborn ; Monitoring, Physiologic ; Troponin ; blood

OBJECTIVETo investigate the protective effect of verapamil and hypothermia on the spermatogenesis of rats after testicular torsion.

METHODSSixty healthy pubertal male Sprague-Dawley rats were equally divided into 5 groups: A (testis torsion), B (testis torsion + verapamil), C (testis torsion + hypothermia), D (testis torsion + verapamil + hypothermia) and E (control). After treatment, the left testis was removed for the observation of the histological changes under the microscope and measurement of the percentage of apoptotic cells by flow cytometry.

RESULTSHE staining showed disordered arrangement, reduced layers and decreased number of spermatogenic cells, apoptotic bodies, necrosis and partial invasion of inflammatory cells in all the groups but E, most obvious in Group A. The apoptosis rates of germ cells in Groups A, B, C, D and E were (32.11 +/- 2.20)%, (20.18 +/- 1.50)%, (20.02 +/- 1.90)%, (13.75 +/- 1.40)% and (8.56 +/- 0.90)%, respectively, and the Makler scores in the 5 groups were (14.47 +/- 1.35), (15.45 +/- 0.75), (15.48 +/- 0.75), (16.22 +/- 0.72) and (19.60 +/- 0.56), respectively, both with statistically significant differences (P < 0.01).

CONCLUSIONThe increased apoptosis of germ cells after testicular torsion-and-reposition may reduce the spermatogenesis of the testis. Either verapamil or local hypothermia can enhance testicular resistance against injuries, and the combination of the two can more efficiently prevent the germ cells from apoptosis.

Animals ; Apoptosis ; Hypothermia, Induced ; Male ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; physiopathology ; therapy ; Spermatic Cord Torsion ; physiopathology ; therapy ; Spermatogenesis ; Verapamil ; therapeutic use

OBJECTIVETo compare the effects of acupuncture anesthesia (AA) and local anesthesia (LA) on the blood pressure (BP) and the heart rate (HR) in chronic rhinitis patients accompanied inferior turbinate hypertrophy in low temperature radiofrequency ablation (RFA).

METHODSTotally 61 chronic rhinitis patients accompanied inferior turbinate hypertrophy were randomly assigned to the AA group (31 cases) and the control group (30 cases). All patients received RFA respectively under AA and RA. Their heart rate (HR), systolic pressure (SP), diastolic pressure (DP), and mean pressure (MP) were recorded and compared at 10 minutes after their entry into the operating room, immediately before surgery, intraoperation, and 5 min after operation.

RESULTSWhen compared with the control group at the same time points, the SP, DP, MP, and HR all decreased at intraoperation and 5 min after operation in the AA group. There was statistical difference in the SP on the right side at the 2nd melting point and the HR on the left side at the 2nd melting point between the two groups (P < 0.05). Compared with the same group at 10 min after entry into the operating room, the SP on the right side at the 1st melting point, the SP, DP, and MP on the right side at the 2nd melting point, the SP, DP, and MP on the left side at the 1st melting point, and the SP on the left side at the 2nd melting point all obviously increased with statistical difference (P < 0.05, P < 0.01). When compared with the same group at 10 min after entry into the operating room and immediately before surgery, there was no statistical difference in the SP, DP, MP, or HR of the AA group at intraoperation and 5 min after operation (P > 0.05). When compared with the same group at 10 min after entry into the operating room and immediately before surgery, there was no statistical difference in HR of the control group at intraoperation and 5 min after operation (P > 0.05).

CONCLUSIONPatients undergoing AA had less fluctuation of the BP and the HR, indicating AA had better analgesic effects.

Acupuncture Analgesia ; Adult ; Anesthesia, Local ; Blood Pressure ; Catheter Ablation ; methods ; Female ; Heart Rate ; Humans ; Hypertrophy ; physiopathology ; surgery ; Hypothermia, Induced ; Male ; Middle Aged ; Rhinitis ; physiopathology ; surgery ; Turbinates