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PubMed1980

Cardiac arrest and reactivation by changes of temperature in the isolated, blood-perfused canine heart.

Effects of temperature for inducing cardiac arrest by cooling and the reactivation by rewarming were investigated in the spontaneously beating canine atrium. Moreover, effects of temperature on paced atria and ventricles were also studied. By cooling, atrial rate was linealy decreased from 111 beats/min and then sinus arrest occurred at 20 +/- 0.3 degrees C (mean +/- SE). Just before the arrest, sinus rate was 29 +/- 2.7 beats/min in 6 atrial preparations. On the other hand, atrial contraction was rather increased until about 25 degrees C and then slightly decreased by cooling. In paced preparations, contraction of the atrium and ventricle initially increased and then decreased with pulsus alternans below the control level by cooling. Finally, pacing failure usually occurred. When the reactivation was induced by rewarming after atrial arrest, atrial rhythm was suddenly recovered at about 25 degrees C, but the contraction was minimum and gradually recovered to the control level. From these results, it is suggested that atrial arrest by cooling may be due to sinoatrial conduction block and that the sinoatrial junction area may have an important role on the reactivation by rewarming. Moreover, the recovery of contraction by rewarming may be affected by several factors which may depress the tension development.

Animals↗
PubMed1995

A method of short-term cryostorage and selection of viable sperm for use in the various assisted reproductive techniques.

The objective of this study was to determine if spermatozoa, following short-term cryostorage at 5 degrees C in Test-Yolk buffer (TYB; ZBL, Inc., Lexington, KY, USA), could be recovered and improved via the SpermPrep filtration method and to assess the possibly enhanced fertilizing capacity of the selected spermatozoa. Semen specimens from 20 men were collected, evaluated, diluted 1:1 (v/v) with TYB, divided into aliquots and cooled to 5 degrees C for 24 and 48 hr. Semen samples were assessed for volume, sperm count, percentage and grade of motility, percentage of morphologically normal spermatozoa and outcome of the sperm penetration assay (SPA). After storage, aliquots were rewarmed at 37 degrees C, centrifuged, and the pellet was resuspended in 1.0 ml of SpermPrep media (ZBL, Inc.). Following 15 min of incubation, the rewarmed spermatozoa were filtered via the SpermPrep I filtration column (ZBL, Inc.) and assessed accordingly. The results obtained in this study indicate that the short-term cryostorage procedure yielded spermatozoa of adequate qualitative characteristics when compared to the fresh spermatozoa. Furthermore, filtration of rewarmed specimens yielded spermatozoa of significantly higher qualitative characteristics and superior fertilizing capacity following a short-term cryostorage period in TYB when compared to fresh and rewarmed spermatozoa (p < 0.05). This method of short-term cryostorage in TYB and selection of superior spermatozoa via the SpermPrep filtration method could further enhance the fertilizing ability of patients who produce spermatozoa characterized by deficient capacitation, acrosome reaction and subsequent fertilization.

Cryopreservation↗
PubMed1998

Cold-induced microtubule disruption and relocalization of membrane proteins in kidney epithelial cells.

Cold preservation of kidneys is commonly used in human transplantation and in vitro studies. However, although disruption of the cytoskeleton by cold has been demonstrated in cultured cells, the effect of cold treatment on intact kidney is poorly understood. In this study, specific antibodies were used to examine the effect of hypothermia on the cytoskeletal network and the trafficking of some membrane proteins in the urinary tubule. Rat kidneys were cut into thin slices (approximately 0.5 mm) that were divided into several groups: (1) some were immediately fixed in paraformaldehyde, sodium periodate, and lysine (PLP); (2) some were stored at 4 degrees C for 15 min or 4 h before being fixed in cold PLP; or (3) after 4 h cold treatment, some slices were rewarmed to 37 degrees C for 15, 30, and 60 min in a physiologic solution, pH 7.4, and were then fixed in warm PLP. Immunofluorescence staining revealed an almost complete disruption of the microtubule network in proximal tubules after 15 min cold treatment, whereas microtubules in other segments were affected after 4 h. A partial recovery of the microtubule network was observed after 60 min rewarming. In contrast, actin filaments seemed to be resistant to cold treatment. gp330, aquaporin-2, H+ ATPase, and the AE1 anion exchanger were all relocated into numerous vesicles that were distributed throughout the cytoplasm after hypothermia followed by rewarming, whereas Na-K-ATPase retained its basolateral localization. The vasopressin-stimulated insertion of aquaporin-2 water channels into the apical membrane was inhibited during the initial rewarming period after cold exposure. Thus, cold preservation of tissues might impair, at least transiently, the polarized membrane expression and function of some transport proteins in renal epithelial cells.

Actins↗
PubMed1988

Metabolic heat production of neonatal calves during hypothermia and recovery.

Metabolic heat production and rectal temperature were measured in 19 newborn calves (41.8 +/- 3.7 kg) during hypothermia and recovery when four different means of assistance were provided. Hypothermia of 30 degrees C rectal temperature was induced by immersion in 18 degrees C water. Calves were rewarmed in a 20 to 25 degree C air environment where thermal assistance was provided by added thermal insulation or by supplemental heat from infrared lamps. Other calves were rewarmed by immersion in warm water (38 degrees C), with or without a 40-ml drench of 20% ethanol in water. Resting (prehypothermia) and cold-induced summit metabolism of the calves was 2.5 +/- .1 and 8.2 +/- .22 W/kg and occurred at rectal temperatures of 39.5 +/- .06 and 36.2 +/- .26 degrees C, respectively. During cooling, metabolic heat production declined at the rate of .65 W/kg per degrees C decline in rectal temperature. The time required to regain euthermia from a rectal temperature of 30 degrees C was longer for calves with added insulation and those exposed to heat lamps than for the calves in the warm water and warm water plus ethanol treatments (90 and 92 vs 59 and 63 +/- 6.4 min, respectively). During recovery, the calves rewarmed with the added insulation and heat lamps produced more heat metabolically than the calves rewarmed in warm water. Total heat production during recovery was 34.1, 31.1, 18.3, 16.9 +/- 1.07 kJ/kg for the calves with added insulation, exposed to the heat lamps, in warm water and in warm water plus an oral drench of ethanol, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Reduction of cold injury by superoxide dismutase and catalase.

The pathophysiology of cold injury was examined by cooling a hind leg of an anesthetized New Zealand white rabbit. A flow probe and a thermocouple were placed in the leg to be cooled to monitor the blood flow and tissue temperature. After baseline measurements, the leg was cooled with a freezing mixture up to 0 degrees C, which was followed by rewarming. The other leg served as control. In the experimental group, liposome-bound superoxide dismutase and catalase were infused through the femoral vein 15 minutes prior to putting the freezing mixture on the leg. Salicylic acid was injected through the femoral vein at the end of some experiments to assay hydroxy radical (OH). Our results demonstrated reduction of local blood flow in cold-exposed leg, indicating development of ischemia. Creatine kinase and lactage dehydrogenase were increased during rewarming in conjunction with hydroxyl radical formation, phospholipid breakdown, and lipid peroxidation. Treatment with superoxide dismutase and catalase reduced OH formation, prevented phospholipid degradation, and decreased creatine kinase, lactate dehydrogenase, and malonaldehyde formation. These results indicate that rewarming of cooled tissue is associated with "rewarming injury" similar to "reperfusion injury", and that oxygen-derived free radicals play a significant role in the pathophysiology of such injury.

Animals↗
PubMed1975

Treatment of experimental frostbite with intra-arterial sympathetic blocking drugs.

A number of experimental and clinical studies have shown that early regional surgical sympathectomy decreases tissue loss following frostbite, presumably by relieving vasospasm and increasing blood flow. This study was performed to determine if a decrease in tissue loss following a standard cold injury could be obtained following a regional "medical sympathectomy" achieved by the intra-arterial administration of sympathetic blocking drugs. A standard cold injury was produced in rabbits and the animals were divided into nine treatment groups. Various treatment modalities were evaluated, including rapid rewarming, intra-arterial reserpine and tolazoline, and intravenous low molecular weight dextran. In the slowly rewarmed animals, the usual clinic situation, the regional intra-arterial administration of reserpine and tolazoline significantly reduced tissue loss, equalling the results obtained in the rapidly rewarmed group. These results indicate that the early achievement of a regional "medical sympathectomy" may be of benefit in reducing tissue loss following frostbite in patients, especially in those in whom rapid rewarming cannot be performed.

Animals↗
PubMed2002

Effects of pH management during deep hypothermic bypass on cerebral microcirculation: alpha-stat versus pH-stat.

OBJECTIVE: There is controversy regarding the optimal pH strategy during deep hypothermic bypass in children. We directly visualized the effects of the pH-stat and alpha-stat strategy on cerebral microcirculation (including leukocyte/endothelial cell interactions) in a piglet model using intravital fluorescence microscopy. METHODS: Two groups of 5 piglets (mean weight 9.6+/-1.3 kg) with a cranial window over parietal cerebral cortex underwent 10-minute normothermic bypass, 40-minute cooling on cardiopulmonary bypass ([CPB] Hct 30%, 100 mL/kg/min), 60-minute circulatory arrest at 15 degrees C, and 40-minute rewarming with alpha-stat (group alpha) or pH-stat (group pH). Plasma was labeled with fluorescein-ITC-dextran for assessment of microvascular diameter. Circulating leukocytes were labeled and observed in postcapillary venules for adhesion before and up to 120 minutes after CPB. Cerebral tissue oxygenation was evaluated by quantification of NADH autofluorescence, which increases during ischemia. RESULTS: At the end of normothermic bypass diameter of cerebrocortical microvessels increased to 116+/-9% (alpha) versus 119+/-10% (pH) of pre-CPB baseline values. During cooling microvascular diameter decreased in group alpha and significantly increased in group pH (89+/-11% (alpha) versus 132+/-13% (pH) at the end of cooling; P<0.001). During the first 10 minutes of rewarming, the cerebral microvascular diameter was significantly larger when the pH stat strategy was used. Tissue oxygenation at the end of cooling was significantly greater in the pH-stat group (P=0.008). On reperfusion, the pH-stat strategy resulted in significantly more rapid return of tissue oxygenation toward baseline although at the end of rewarming the metabolic recovery was complete in both groups. The whole body lactate during early rewarming was significantly less with the pH stat strategy. There was no significant difference between the groups regarding the number of adherent leukocytes throughout the time course of the experiment. CONCLUSIONS: pH-stat management increases tissue oxygenation during deep hypothermic bypass and after circulatory arrest. Leukocyte/endothelial cell interactions during hypothermic bypass are mild with both alpha-stat and pH-stat.

Animals↗
PubMed1992

Accidental hypothermia.

Hypothermia continues to be a major public health problem and a challenge to health care providers. The very young, the very old, and the poor are at greatest risk. Life-threatening physiologic changes make rapid rewarming mandatory. Numerous rewarming methods have been described in the literature; the decision to use any of the methods available depends on the degree of hypothermia present, the condition of the patient, and the rewarming rate possible with the method chosen. Cardiopulmonary bypass, if available, is the optimal method for rewarming the severely hypothermic patient.

Algorithms↗
PubMed2005

[Effects of taurine on early changes of excitatory amino acids in rabbit brain due to deep hypothermic circulatory arrest].

OBJECTIVE: To study the effects of taurine (Tau) on early changes of excitatory amino acids (EAA) in hippocampus rabbit brain due to deep hypothermic circulatory arrest (DHCA). METHODS: Sixteen New Zealand rabbits were randomly allocated into 2 groups: Tau 150 mg/kg group (group I, n = 8), control group (group II, n = 8). Cardiac pulmonary bypass (CPB) was set up after cerebral microdialysis model was established. High performance liquid chromatography was employed to monitor the continuous changes of glutamic acid (Glu), aspartic acid (Asp), Tau and glycine (Gly) in the hippocampus CA1 region at anaesthesia periods, CPB stage, pre 30 minutes in DHCA, post 30 minutes in DHCA, pre 30 minutes in rewarming, post 30 minutes in rewarming. RESULTS: The increase of Glu in group II was (5.1 +/- 1.5) and (4.1 +/- 1.4) times higher than that at anaesthesia periods (t = 3.74, 5.45, P < 0.01), and the increase of Glu in group I was (2.1 +/- 1.5) and (1.1 +/- 0.4) times than that at anaesthesia periods at pre 30 minutes and post 30 minutes rewarming stage respectively. Rising of Gly in group II was 6.7 (3.6, 13.6) times than that at anaesthesia periods (T = 75.00, P < 0.05), the rising of Gly in group I was 4.2 (3.8, 11.5) times at post 30 minutes in DHCA. Rising of Tau in group I was 6.9 (3.0, 14.2) and 10.6 (2.8, 22.5) times than that at anaesthesia periods (T = 75.00, P < 0.05 and T = 90.00, P < 0.05) and rising of Tau in group II was 4.0 (3.0, 5.7) and 3.2 (1.2, 7.6) times than that at anaesthesia periods at post 30 minutes in DHCA and pre 30 minutes rewarming stage respectively. Asp was no evident change at every periods. CONCLUSION: DHCA might increase the excitatory amino acids in the early phases of circulatory restoration. Exterior Tau 150 mg/kg could inhibit release of EAA.

Animals↗
PubMed2005

In vitro validation of the Affinity NT oxygenator arterial outlet temperatures.

During cardiopulmonary bypass, the rates of cooling and rewarming and the maximum temperatures attained are implicated in patient morbidity. Thus, accurate oxygenator arterial outlet temperature measurements are needed. The purpose of this study was to determine the accuracy of the arterial outlet temperature probe on the "Affinity NT" membrane oxygenator in measuring perfusate temperatures. An in vitro circuit was used. Crystalloid solution was recirculated through an Affinity NT membrane oxygenator and, to simulate the patient, a second oxygenator. Water was recirculated through the heat exchanger of the second oxygenator via a reservoir. A myocardial temperature probe was inserted in-line 4 cm distal to the Affinity NT oxygenator arterial outlet temperature probe and was considered to measure the actual temperature of the perfusate. Temperatures were simultaneously recorded from the in-line probe, arterial outlet probe, and reservoir every second. Twenty-seven trials were run using random combinations of three Affinity NT oxygenators and three in-line probes. Each trial entailed cooling an initially normothermic reservoir to 28 degrees C and then rewarming it to normothermia again. The arterial outlet temperature probe on the Affinity NT membrane oxygenator underestimated the perfusate temperatures during early rewarming (bias of 0.72 degrees C; precision of +/-1.15 degrees C) and late rewarming (bias of 0.52 degrees C; precision of +/-0.97 degrees C). An overestimation of the perfusate temperatures occurred during early cooling (bias of -0.57 degrees C; precision of +/-1.37 degrees C). Only during the late cooling phase was the arterial outlet temperature probe accurate (bias of -0.02 degrees C; precision of +/-0.3 degrees C). The perfusionist should be aware of the temperature probe monitoring characteristics of the oxygenator to safely perfuse the patient.

Cardiopulmonary Bypass↗
PubMed1992

Effects of Prior Physical Activity on Skin Surface Temperature Response of the Ankle During and After a 30-minute Ice Pack Application.

The effects of various durations of treadmill running on ankle skin temperature response during and following ice application were investigated. We measured the ankle skin surface temperature of 12 male subjects with a telethermister (YSI Model 44) during each of three conditions: control and two exercise conditions that involved treadmill running for 15 or 30 minutes, followed by a 30-minute ice pack application and 90 minutes rewarming. The control condition involved no exercise prior to ice pack application. Ankle skin temperature increased significantly during 15 and 30 minutes of exercise, although the temperature difference between the two conditions was not statistically significant. Mean skin cooling temperatures were slightly, though not significantly, higher following exercise than following no exercise. The rate of cooling, however, was unaffected by prior exercise. Mean skin temperatures during rewarming were significantly higher following the exercise conditions, but the rate of rewarming was unchanged by exercise. Mean rewarming temperatures were higher in the 30-minute exercise condition than in the 15-minute exercise condition. Longer ice applications or shorter reapplications may be necessary following exercise of at least 15 minutes, but further investigation is necessary to substantiate this supposition.

Journal Article↗
PubMed1996

Ankle and thigh skin surface temperature changes with repeated ice pack application.

OBJECTIVE: Most of the research on cold applications has been performed on nonexercising supine subjects during a single cold pack application. Most athletic injuries occur during exercise, which increases skin temperature. Exercise before ice application will also increase ankle skin temperature during the rewarming phase. The purpose of this study was to examine the effects of activity on subsequent ice pack applications and rewarming using standard immediate care procedures. DESIGN AND SETTING: Three experimental conditions (20-, 30-, and 40-minute ice pack applications) were applied to 12 subjects in a repeated measures design. Subjects rode a bicycle ergometer for 15 minutes before ice application to the ankle and opposite thigh, and were active (walking with crutches, simulated showering and dressing) for 20 minutes following application. Subjects rested with the limb elevated for an additional 40 minutes. Ice packs were then reapplied for the appropriate time (20, 30, or 40 minutes) followed by 60 minutes of rest with the limb elevated. SUBJECTS: Twelve (8 males, 4 females) college-aged volunteers. Only subjects with good-to-high fitness levels were accepted for this study. MEASUREMENTS: Ankle skin, thigh skin, and atmospheric temperatures were measured every minute using an Isothermex (Columbus Instruments, Columbus, OH). RESULTS: Thigh temperature changes during the first ice application were greater during the 30- and 40-minute conditions than the 20-minute condition. Ankle and thigh temperature changes during the first ice application and rewarming, and for the entire trial were greater during the 40-minute condition than the 20-or 30-minute conditions. Throughout the first ice application and rewarming, and the entire trial, thigh temperature changes were greater during the 30-minute condition than the 20-minute condition. CONCLUSIONS: During immediate care procedures following injury, ice packs should be reapplied immediately following showering, changing clothes, and returning home.

Journal Article↗
PubMed2000

Induced and accidental hypothermia.

OBJECTIVE: To review human thermoregulation and the pathophysiology and management of induced and accidental hypothermia. DATA SOURCES: A review of studies reported over ten years from 1990 to 2000 and identified through a MEDLINE search of the English-language literature on thermoregulation and induced and accidental hypothermia. SUMMARY OF REVIEW: Hypothermia is defined as a core temperature less than 35 degrees C, and may be therapeutic (i.e. induced for clinical benefit) or accidental. Hypothermia induced prior to cardiovascular or neurosurgical procedures (i.e. therapeutic hypothermia) allows for a greater hypotensive operative period with less risk of cerebral or cardiac ischaemic injury. Hypothermia induced following tissue injury (e.g. closed head injury, cerebrovascular accident, adult respiratory distress syndrome) has also been used to reduce ischaemic tissue injury, although significant clinical benefits have not yet been demonstrated. Inadvertent hypothermia (i.e. accidental hypothermia) is classed as mild from 33 degrees C-35 degrees C, moderate from 30 degrees C-33 degrees C and severe if less than 30 degrees C. Treatment includes surface and core warming methods, all of which have a valid basis from experimental studies. However, no prospective, randomised controlled clinical trials exist that have compared the various rewarming methods. Currently, passive rewarming methods (e.g. reflective metalloplastic sheets, blankets) are recommended for patients with mild hypothermia (> 33 degrees C), active surface rewarming (e.g. heated blankets, hot air circulators) for moderate hypothermia (> 30 degrees C), active core rewarming (e.g. heated haemodialysis, haemodiafiltration or peritoneal dialysis) for severe hypothermia (< 30 degrees C), and heated cardiopulmonary bypass for severe hypothermia with cardiopulmonary arrest. CONCLUSIONS: Operative hypothermia reduces ischaemic injury during cardiac and neurosurgical procedures. Hypothermia induced following tissue injury has not yet been shown to be of benefit. Management of accidental hypothermia requires passive and active warming methods, the indication of each depending on the availability of the method and severity of hypothermia.

Journal Article↗
PubMed2006

[Pathophysiology and management of perioperative hypothermia].

The paper is a review of pathophysiology and management of perioperative hypothermia. The advanced methods of rewarming, such as passive and active: external and core used in clinic allow for efficient management ant prophylactics of hypothermia. Thermotherapy with use of infrared ceiling heaters CTS and mobile MTC as well as Infutherm system applying by authors are desirable and even indispensable in contemporary equipment of surgery clinics, cardiovascular surgery clinics and burn centers. The ideal rewarming method should be safe and enable fast, reliable and predictable warming or rewarming. The clinical parameter to determine the efficacy of rewarming is the change of core temperature. There is no doubt that active warming with forced-air warmers (Warm Touch 5700 and Bair Hugger 500) or radiative heaters (IR-A:Hydrosun 500, IR-C radiation: CTC X, MTC) is more effective than use of standard, passive insulation hospital blankets or convectional heaters. Actually the forced-air warmers are counted to be more useful in cardiovascular surgery hypothermia management, because of fast rate core temperature rise and faster rise in mean skin temperature compared to the control group. CTC X and MTC Aragona radiative heaters are useful in burn management being the most effective when the distance of heater from the patient body is less than 80 cm. The observation of 60 consecutive extensive burns leads to conclusion that long-lasting dressings in burn patients when the whole body is not covered and protected, can be performed safely only in conditions excluding heat losses and core temperature drop. While the cold intravenous fluids may significantly contribute to the temperature drop depending on the volume infused, the use of fluids warming systems as well as external heat application is absolutely indicated to improve the heat balance of the patient body.

Burns↗
PubMed1991

[Accidental hypothermia. Risk factors in 29 patients with body temperature of 30 degrees C and below].

29 patients with a body temperature below 30 degrees C (mean 26.4 degrees C) were treated during the period 1982-88, both years inclusive. Eight patients were severely hypotensive (systolic blood pressure less than 60 mm Hg) and two had ventricular fibrillation on admission. Bradycardia (less than 60 beats per minute) was noted in ten patients. 12 patients were rewarmed by surface warming, 17 by extracorporeal circulation with femoral cannulation. 22 patients (76%) were discharged alive. Age, sex, body temperature, method and rate of rewarming, serum electrolytes, acidosis and the use of blood components did not influence the outcome. Renal failure was the only complication associated with a fatal outcome. Severe hypotension on admission tended to increase mortality, but logistic regression analysis identified the mode of cooling as the only independent risk factor for death. A patient cooled indoors had an odd risk of 10.6 of hospital mortality compared to one found outdoors. For the sake of convenience, in hospitals with the available resources rewarming by extracorporeal circulation may be used in patients with circulatory arrest, since this is the easiest way to control and support failing circulation. In all other cases carefully monitored surface rewarming should be used as this necessitates less use of hospital resources and produces equally good results.

Accidents↗
PubMed1991

Hypothermic preservation of hepatocytes. III. Effects of resuspension media on viability after up to 7 days of storage.

Hepatocyte suspensions provide a rapid method to determine how hypothermic storage affects liver cell metabolism and viability. Using these studies, improved methods of hypothermic liver preservation for transplantation may be developed. In this study, rat hepatocytes were cold-stored for up to 7 days in University of Wisconsin liver preservation solution. At the end of each day of storage hepatocytes were resuspended in Krebs-Henseleit buffer or tissue-culture medium (Liebovitz-15; Fischer's; modified Fischer's, which was similar to Fischer's but with glycine and cysteine added; or Waymouth's medium). Hepatocyte viability was assessed by rewarming and oxygenating the suspensions and measuring the percentage of leakage of lactate dehydrogenase from the cells, the cellular concentration of potassium and the stimulation of respiration by succinate, all measures of plasma membrane integrity. Additionally, concentrations of ATP and glutathione after rewarming and reoxygenation in the various resuspension media were measured. Hepatocyte permeability to lactate dehydrogenase did not increase during cold storage of 1 to 7 days (7.2% +/- 2% leakage), indicating that most of the hepatocytes remained viable during cold storage. However, when rewarmed, loss of viability (leakage of lactate dehydrogenase) was dependent on the composition of the resuspension media. In Krebs-Henseleit buffer, viability was reduced after 2 and 3 days of storage (lactate dehydrogenase leakage on rewarming = 70% to 90%). Leakage of lactate dehydrogenase was reduced significantly after resuspension in tissue-culture media. After 6 days of storage, lactate dehydrogenase leakage from hepatocytes stored in Liebovitz- 15 or modified Fischer's was only about 30%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

[The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion].

The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion were compared with non-pulsatile pumping. Twelve dogs were classified into 2 groups by the perfusion technique used. Animals were core cooled to 20 degrees C esophageal temperature with 80 ml/kg/min perfusion rate and maintained at the level for 2 hours with low flow perfusion (LFP) (30 ml/kg/min), then rewarmed to 35 degrees C with 80 ml/kg/min flow rate. As compared with the non-pulsatile group, pulsatile group demonstrated greater urine output during rewarming (p less than 0.05) and greater lymph flow during core cooling (p less than 0.05). The non-pulsatile group showed higher lymph/plasma protein concentration ratio (Lc/Pc) during LFP and rewarming (p less than 0.05), and greater plasma protein clearance during rewarming (p less than 0.05), and much higher increase of interstitial fluid pressure. The lesser water retention during bypass was also noted in the pulsatile group (28.6 +/- 27.6 ml/kg vs 85.4 +/- 52.1 ml/kg, p less than 0.05). These findings have suggested that the pulsatile perfusion may be useful for the infant cardiopulmonary bypass reducing tissue edema and preserving better renal function.

Animals↗
PubMedDate not supplied

The significance of colloid osmotic pressure during induced hypothermia.

Colloid osmotic pressure (COP) during hypothermia with and without total circulatory arrest was evaluated in 20 adult mongrel dogs (average body weight = 18.6 kg). All animals were surface-cooled to 20 degrees C (rectal temperature) under halothane-diethyl ether azeotrope anesthesia and divided into 4 equal groups. In Groups I (non-arrest) and II (60 minute-arrest) 10% low molecular weight dextran (LMWD; 1 gm/kg = 10 ml/kg) was administered during cooling. Physiological saline (10 ml/kg) was given in Groups III (non-arrest) and IV (60 minute-arrest) during cooling. COP in LMWD groups increased significantly during cooling and was consistently higher than it was in the saline groups during rewarming. There were no significant differences in heart rate (HR), mean arterial pressure (MAP), central venous (CVP) and pulmonary artery wedge pressures (PAW) between the 4 groups during cooling. The increase in hematocrit (Hct) in animals that received saline was significant at the end of cooling and during rewarming. Hct was not significantly changed in Group I throughout the procedure, whereas in Group II (60 minute-arrest) it increased significantly during rewarming despite the administration of LMWD. Rewarming time in Group II was significantly shorter than in Group IV (144.2 +/- 9.6 min vs 193.2 +/- 32.6 min, respectively). We conclude that the administration of LMWD effectively reduces hemoconcentration and is also beneficial for maintaining better peripheral circulation.

Animals↗