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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To facilitate perfusion rewarming without the use of total body heparinization or an oxygenator following open-heart correction with surface hypothermia, we divised a pump circuit. The circuit, totally primed with 100 c.c. of saline, consists of polyurethane-polyvinyl-graphite (PPG) coated Tygon tubes (with one end tapered by heat treatment) and a copper-coil heat exchanger. A roller pump was used to achieve partial bypass from the left atrium to the ascending aorta with flow rates up to 70 c.c. per kilogram per minute. Experiments in dogs resulted in rapid rewarming, immediate return of cardiac function, and hematologic alterations similar to those noted during surface rewarming. The safety of the method was also demonstrated. Prothrombin time, partial thromboplastin time, and platelet values returned to control levels upon rewarming, and no thromboemboli or bleeding problems were noted. Six clinical experiences were accumulated. Details of the method, hematologic and blood chemical analyses in dogs, and the first clinical trial in a 3-month-old infant with transposition of the great vessels are reported.
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PMID:Heparinless, oxygenatorless perfusion rewarming following surface-induced deep hypothermia for open-heart surgery. 126 65

Ten percent pentastarch is a low-molecular-weight hydroxyethyl starch with greater oncotic pressure and shorter intravascular persistence than 6% hetastarch. To evaluate its safety and efficacy as a component of cardiopulmonary bypass priming solution, we prospectively studied 90 patients undergoing coronary artery bypass grafting or valve replacement necessitating cardiopulmonary bypass (bubble oxygenator and moderate systemic hypothermia). Sixty patients were randomized to receive 75 gm of either 10% pentastarch (group P) or 25% albumin (group A), and 30 patients received lactated Ringer's solution alone (group C). Intravascular colloid osmotic pressure during cardiopulmonary bypass was highest with either of the colloid primes (15-minute measurement: group P, 15.7 +/- 2.2 mm Hg (mean +/- standard deviation); group A, 15.2 +/- 2.0 mm Hg; group C, 11.3 +/- 1.7 mm Hg; p less than 0.05, groups P and A compared with group C). This was associated with a lower volume requirement during cardiopulmonary bypass to maintain the venous reservoir (group P, 333 +/- 318 ml; group A, 483 +/- 472 ml; group C, 1332 +/- 1013 ml; p less than 0.05, groups P and A compared with group C). Urine output during cardiopulmonary bypass was similar in each group. Net intraoperative fluid balance was lowest in the colloid groups (groups P and A, 5.7 +/- 1.4 L; group C, 6.9 +/- 1.3 L; p less than 0.05, groups P and A compared with group C). Cardiac index shortly after weaning from cardiopulmonary bypass was greatest in group P (group P, 3.2 +/- 0.9; group A, 2.8 +/- 0.8; group C, 2.7 +/- 0.6 dyne.sec.cm-5; p less than 0.05, group P compared with group C). Changes in alveolar-arterial oxygen gradients, shunt fraction, and effective compliance were similar in all groups. During cardiopulmonary bypass, pentastarch appeared to cause the greatest degree of hemodilution, as suggested by the lowest hemoglobin, factor VII and IX levels and platelet count. The activated partial thromboplastin time was significantly prolonged during and immediately after cardiopulmonary bypass in group P relative to groups A and C (p less than 0.05), although there were no significant differences in the activated clotting time before cardiopulmonary bypass, during cardiopulmonary bypass, or after heparin neutralization. As well, clinical indices of hemostasis, including mediastinal drainage, red cell, platelet, and fresh frozen plasma requirements, and reoperation for excessive postoperative bleeding, were similar. We conclude that pentastarch, when used in cardiopulmonary bypass prime, is as safe as either albumin or Ringer's solution alone.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The safety and efficacy of ten percent pentastarch as a cardiopulmonary bypass priming solution. A randomized clinical trial. 137 60

Hypothermic patients commonly develop coagulopathy, but the effects of hypothermia on coagulation remain unclear because clinical laboratories routinely perform clotting tests only at 37 degrees C. Measurements of activated partial thromboplastin times (APTT), prothrombin times (PT), and thrombin times (TT) were performed on plasma from normothermic and hypothermic rats at a range of temperatures (25 degrees-37 degrees C) to assess the effects of hypothermia on apparent clotting factor levels and clotting factor activities. In general, clotting times were more severely prolonged when test temperatures were hypothermic than when body temperatures were hypothermic. Indeed, little to no prolongation resulted from body hypothermia alone. These findings reveal the observed disparity between clinically evident hypothermic coagulopathy and near-normal clotting studies. Clotting studies performed at 37 degrees C will not confirm hypothermic coagulopathy. These results indicate that the appropriate treatment for hypothermia-induced coagulopathy is rewarming rather than administration of clotting factors.
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PMID:The disparity between hypothermic coagulopathy and clotting studies. 140 19

Planned intra-abdominal packing for surgically uncontrollable hemorrhage from liver and retroperitoneal injuries exacerbated by hypothermia, acidosis, and coagulopathy regained popularity over the past decade. The authors reviewed 39 patients injured between August 1985 and September 1990; 31 packed for liver injuries, eight for nonliver injuries. The overall mortality rate was 44% (17/39); 9 (23%) exsanguinated, 3 (8%) died of head injuries, 3 (8%) of multisystem organ failure, 2 (5%) of late complications. The mean age was 33.9 +/- 16.2 (range, 16 to 79); there were 26 men and 13 women. Relaparotomy for pack removal was performed 2.0 +/- 1.1 days (range, 1 to 7) after initial operation. The authors identified intraoperative risk factors of pH less than or equal to 7.18, temperature less than or equal to 33 C, prothrombin time greater than or equal to 16, partial thromboplastin time greater than or equal to 50, and transfusion of 10 units or more of blood as highly predictive of outcome. Patients with four to five risk factors (n = 3) had a 100% mortality rate (p less than 0.04); two to three risk factors (n = 12), 83% mortality rate (p less than 0.003), compared with zero to one risk factors (n = 24), 18% mortality rate. Complications developed in six of 22 survivors (27%): 5 abdominal abscesses (23%), 2 wound dehiscences (9%), and 2 enterocutaneous fistulae (9%). Intra-abdominal packing will not stop all bleeding; 23% of the patients exsanguinated. In 77%, packing helped achieve hemostasis we believed was not otherwise possible. Packing may be done to prevent the development of acidosis, hypothermia, and coagulopathy or may be done early in the treatment of cold, acidotic patients rather than massive transfusion in the face of surgically uncorrectable bleeding.
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PMID:Abdominal packing for surgically uncontrollable hemorrhage. 161 83

The rapid infusion system (RIS), which can deliver fluids/blood products rapidly at precise rates and normothermic conditions, was compared with conventional fluid administration (CFA) in a randomized study of 36 hypovolemic trauma patients. Admission stratification criteria of the groups were similar relative to age, Glasgow Coma Score (GCS), Injury Severity Score (ISS) and plasma lactate. Despite the lack of difference in blood loss between the 24-h survivors of the two groups, the CFA group required greater total fluids (23.6/20.21), red blood cells (5.5/4.61), fresh frozen plasma (FFP) (2.8/1.91), platelets (523/204 ml), and crystalloids (12.9/10.61). Lactate levels were lower in the RIS group at virtually all times from hours 1 to 24 (4.3/5.3 mM/l, t-value = 3.3, DF = 279, P = 0.001). Post-admission hypothermia was greater in the CFA group at all times during the first 24 h (35.2/36.4 degrees C, t-value = 5.6, DF = 250, P = 0.001). The mean partial thromboplastin time was significantly higher in the CFA group (47.3/35.1 s, t-value = 3.1, DF = 279, P = 0.002). The PTT and PT were related to the degree of lactic acidosis (P = 0.0001) and hypothermia (P = 0.001) but not to the amount of FFP given (P = 0.14). The hospital costs, days in the ICU, and days on the ventilator were greater for the CFA group, as was the incidence of pneumonia (0/11 vs. 6/17; P = 0.03). Hypovolemic trauma patients resuscitated with the RIS needed fewer fluid/blood products and had less coagulopathy; more rapid resolution of hypoperfusion acidosis; better temperature preservation; and fewer hospital complications than those resuscitated with conventional methods of fluid/blood product administration.
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PMID:The rapid infusion system: a superior method for the resuscitation of hypovolemic trauma patients. 165 23

Previous studies of hypothermia and blood coagulation have focused on alterations in the levels of blood clotting elements using coagulation tests performed under normothermic conditions. However, because of the enzymatic nature of activated clotting factors, hypothermia should also be expected to affect clotting factor activities. Multiple determinations of activated partial thromboplastin times (APTT), prothrombin times (PT), and thrombin times (TT) were performed on commercially available normal human plasma at assay temperatures similar to those encountered clinically (25-37 degrees C). Both the APTT and the PT were significantly prolonged at temperatures below 35 degrees C (P less than 0.05). Clotting time correlated significantly with assay temperature in a negative exponential fashion for all three tests (r = -0.97 for APTT, -0.93 for PT, -0.71 for TT, P less than 0.001 for all regressions). Clotting time prolongation appears proportional to the number of enzymatic steps involved. These data indicate that the coagulopathy observed during hypothermia is, in part, independent of clotting factor levels.
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PMID:Hypothermia and blood coagulation: dissociation between enzyme activity and clotting factor levels. 225 17

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.
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PMID:Heparinless extracorporeal bypass for treatment of hypothermia. 229 71

Puppies 6-12 kg underwent cardiopulmonary bypass with profound hypothermia. Thirteen animals received 200 ng kg-1 min-1 of PGI2 during bypass whilst 11 control animals received equivalent volumes of glycine buffer (placebo) over a similar period. Results indicated preservation of platelets, leukocytes and fibrinogen levels, together with shortened activated partial thromboplastin times and fewer fibrinogen degradation products post-bypass in PGI2-treated animals. There was an initial fall in blood pressure and systemic vascular resistance in PGI2 treated animals, but pulmonary pressures and resistances, cardiac outputs, and heart rates showed no significant differences from controls. Higher and more satisfactory end of bypass and post-bypass blood pressure levels, together with a lesser fall-off in mean total pulmonary compliance, and shortened bypass times were achieved in treated animals. PGI2 appeared to afford some protection against lung damage as observed by histological studies. All beneficial effects appeared to be significantly greater amongst smaller animals. The results indicate possible benefits from the use of PGI2 in infant open heart surgery.
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PMID:The effects of prostacyclin (PGI2) on haematological and haemodynamic parameters, and lung histology in puppies undergoing cardiopulmonary bypass surgery with profound hypothermia. 388 67

In the present study, an effort was made to establish the procedure for 60 minutes selective profound hypothermia below 20 degrees C of the abdominal viscera. In 6 mongrel dogs, hemodynamic changes were investigated during 60 minutes normothermic vascular exclusion of the abdominal viscera by occluding the aorta and inferior caval vein just above the diaphragm. Hemodynamic state just after the combined occlusion of these vessels was stable, but 60 minutes occlusion was followed by hypoperfusion of the cranial half of the body. In 15 mongrel dogs, the 60 minutes selective profound hypothermia below 20 degrees C of the abdominal viscera was performed after occluding these vessels with an aid of extracorporeal circuit. Pooled blood in the splanchnic region during hypothermia was warmed and drained to jugular vein to maintain the hemodynamic state in the cranial half of the body. Twelve of 15 dogs survived 2 weeks after the procedure with minimal hepatic damage. In 7 mongrel dogs, blood coagulation system was investigated. Decrease of platelet, fibrinogen, plasminogen, anti-thrombin III, prothrombin and cold insoluble globulin concentration, elongation of prothrombin time and partial thromboplastin time, and elevation of FDP occurred during and after the selective profound hypothermia. But these changes were self limiting and recovered soon after heparin neutralization. In 9 mongrel dogs, extended pancreatectomy with splenectomy and combined resection of portal vein using selective profound hypothermia was performed. Bleeding and splanchnic congestion during extended pancreatectomy was minimum. Five of 9 dogs survived 2 weeks with slight hepatic and renal damage.
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PMID:[Experimental studies on the selective profound hypothermia of the abdominal viscera by descending aorta and inferior caval vein occlusion]. 667 63

Hypothermia prolongs clotting times when the tests are performed at hypothermic temperatures, in contrast to standard clinical tests performed at 37 degrees C. The relative impact of hypothermia on plasma clotting factor activity was investigated by determining the specific clotting factor deficiencies required to produce an equivalent effect. Clotting factor concentration curves were constructed for clotting factors II, V, and VII through XII using assayed reference plasma (ARP) diluted with specific factor-deficient plasmas (FDP). Prothrombin times and partial thromboplastin times were measured as appropriate for each factor at test temperatures ranging from 37 degrees to 25 degrees C using a modified fibrometer. The clotting times for each temperature with undiluted ARP were compared with the clotting times at 37 degrees C obtained with FDP dilution. Hypothermia at temperatures below 33 degrees C produces a coagulopathy that is functionally equivalent to significant (< 50% of normal activity) factor-deficiency states under normothermic conditions, despite the presence of normal clotting factor levels.
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PMID:Functional equivalence of hypothermia to specific clotting factor deficiencies. 808 2


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