***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : Hypothermia during and after major abdominal surgery decreases host defenses , increases the incidence of coagulopathy and may alter blood pressure , cardiac contractility and myocardial stability . Methods : We design ed a prospect i ve r and omized study to compare the benefits of a forced air warming system with warm blanket treatments in minimizing the effects of hypothermia on 64 morbidly obese patients undergoing Roux-en-Y gastric bypass .  Results : Patients in the forced air warming group ( n = 32 ) had significantly higher perioperative body core temperature , lower central venous pressure and blood pressure readings , lower incidence of shivering , less blood loss intraoperatively and achieved a higher post anesthesia Aldrete Score than those patients in the warmed blanket group ( n = 32 ) . Conclusion : The forced air warming system is safe , cost effective and beneficial in minimizing the undesirable consequences of hypothermia in morbidly obese patients undergoing Roux-en-Y gastric bypass BACKGROUND Mild perioperative hypothermia , which is common during major surgery , may promote surgical-wound infection by triggering thermoregulatory vasoconstriction , which decreases subcutaneous oxygen tension . Reduced levels of oxygen in tissue impair oxidative killing by neutrophils and decrease the strength of the healing wound by reducing the deposition of collagen . Hypothermia also directly impairs immune function . We tested the hypothesis that hypothermia both increases susceptibility to surgical-wound infection and lengthens hospitalization . METHODS Two hundred patients undergoing colorectal surgery were r and omly assigned to routine intraoperative thermal care ( the hypothermia group ) or additional warming ( the normothermia group ) . The patient 's anesthetic care was st and ardized , and they were all given cefam and ole and metronidazole . In a double-blind protocol , their wounds were evaluated daily until discharge from the hospital and in the clinic after two weeks ; wounds containing culture-positive pus were considered infected . The patients ' surgeons remained unaware of the patients ' group assignments . RESULTS The mean ( + /- SD ) final intraoperative core temperature was 34.7 + /- 0.6 degrees C in the hypothermia group and 36.6 + /- 0.5 degrees C in the normothermia group ( P < 0.001 ) Surgical-wound infections were found in 18 of 96 patients assigned to hypothermia ( 19 percent ) but in only 6 of 104 patients assigned to normothermia ( 6 percent , P = 0.009 ) . The sutures were removed one day later in the patients assigned to hypothermia than in those assigned to normothermia ( P = 0.002 ) , and the duration of hospitalization was prolonged by 2.6 days ( approximately 20 percent ) in hypothermia group ( P = 0.01 ) . CONCLUSIONS Hypothermia itself may delay healing and predispose patients to wound infections . Maintaining normothermia intraoperatively is likely to decrease the incidence of infectious complications in patients undergoing colorectal resection and to shorten their hospitalizations Forced-air warming is the most commonly used and effective method of active warming . A new radiant warming device ( Suntouch ™ , Fisher and Paykel ) may provide an alternative when the skin surface available for warming is limited . We conducted a r and omized controlled trial to compare the efficacy of the Suntouch ™ radiant warmer and forced-air warming . With ethics committee approval , 60 surgical patients having procedures anticipated to be more than two hours in duration were recruited . Patients were r and omized to either radiant warming or forced-air warming . All intravenous fluids were warmed but prewarming was not used . The final intraoperative core temperatures ( ° C ) for the radiant warming and forced-air warming groups were 36.0±0.5 and 36.4±0.6 ( P=0.002 ) respectively . No other patient variables were significantly different . The Suntouch ™ is not as effective as the forced air warming for intraoperative warming during long surgical procedures . The device may be useful when forced-air warming is not possible Unintentional hypothermia is common in patients undergoing " routine anesthesia in surgery " . The aims of the study were to estimate the difference of changes of body temperature during abdominal and limb operations and to evaluate the effectiveness of the heated humidifier for reducing intraoperative heat loss .  Forty-three patients were r and omly being allocated into 3 groups . Group I consisted of 14 patients undergoing abdominal operation without the use of heated humidifier . Another 22 patients were being assigned as group II to have a heated humidifier on the inspiratory limb of the breathing circuit . The inspired gas was warmed to 39 degrees C and the relative humidity was 90 % . 7 patients undergoing limb operation were attributed to group III without using heated humidifier to humidify and warm up the inspired gas . For body temperature monitoring , the probe was placed on the patient 's nasopharynx and the temperature was measured immediately before induction of anesthesia , post-intubation , and then once again every 15 minutes up to 3 hours after induction . All patients in the 3 groups showed a rapid decrease of body temperature in the first hour and then the hypothermic change was slow down . The lowest level of body temperature was reached at about 2 hours after induction . Patients undergoing abdominal operation decreased body temperature greater than those undergoing limb operation for about 2 degrees C after 3 hours of anesthesia and surgery . Warming and humidifying the inspired gas effectively reduced the heat loss . We concluded that abdominal operation induce hypothermia more than limb operation . The use of heated humidifier was effective in maintaining body temperature Background : This study was design ed to compare the efficacy of two different sites of active forced air warming , upper body or lower body , to maintain normothermia ; and their respective effect on thenar skin temperature in relation to the accelerographic monitoring of neuromuscular blockade during long‐lasting abdominal surgery Perioperative hypothermia is a common problem in anesthesia practice . Regional anesthesia , like general anesthesia , influences the thermoregulatory process . The aim of our study was to compare the efficacy of ondansetron and meperidine in the prevention of shivering during and after spinal anesthesia . Methods : In this double-blind study , 75 patients were r and omized into 3 groups . Group O and Group M were given ondansetron 8 mg and meperidine 0.4 mg/kg intravenously immediately before spinal anesthesia , respectively . Group C received saline at identical times . The core temperatures and the incidence of shivering were recorded . Association between maximum block height and mean rectal temperatures of the patients were also evaluated . Results : The core temperature was preserved in both ondansetron and meperidine groups with respect to the control group . Shivering was observed in 8 % of patients in groups O and M and 36 % in group C. The correlation between maximum block height and mean rectal temperatures was lost in the ondansetron and meperidine groups . Conclusion : Ondansetron and meperidine have similar antishivering effects . In addition , both ondansetron and meperidine altered the correlation between the core temperature and block level during spinal anesthesia We evaluated the efficacy of forced‐air warming to maintain normothermia during liver transplantation . In a prospect i ve , clinical trial 20 patients were r and omly assigned to  routine thermal management ( circulating‐water mattress set at 42 ° C , intravenous fluid warming to 37 ° C and passive insulation ) or routine management with additional forced‐air warming of head , chest , and arms . Core temperature was measured in the pulmonary artery . Morphometric and demographic characteristics were similar in each group , as was total administered fluid volume replacement . Core temperatures in each group decreased by about 0.6 ° C during the first 70min of anaesthesia and then by 0.9 ° C within 90 to 120 min in the patients given routine thermal management , but only by 0.4 ° C in those warmed with forced‐air . Subsequently , core temperatures in the control group increased to only 35.7 , SD 0.25 ° C whereas those in the patients given forced‐air warming increased to 36.5 , SD 0.2 ° C . Despite the relatively high ambient temperature , patients warmed only with a circulating‐water mattress and passive insulation became hypothermic during surgery . In contrast , when forced‐air warming was added to this routine thermal management , patients were normothermic at the end of surgery . Forced‐air warming  prevented intra‐operative hypothermia during liver transplantation CONTEXT AND OBJECTIVE Inadvertent perioperative hypothermia is common during spinal anesthesia and after midazolam administration . The aim of this study was to evaluate the effects of intraoperative skin-surface warming with and without 45 minutes of preoperative warming in preventing intraoperative and postoperative hypothermia caused by spinal anesthesia in patients with midazolam premedication . DESIGN AND SETTING Prospect i ve and r and omized study at Hospital das Clínicas , Universidade Estadual Paulista , Botucatu . METHODS Thirty patients presenting American Society of Anesthesiologists ( ASA ) physical status I and II who were scheduled for elective lower abdominal surgery were utilized . The patients received midazolam premedication ( 7.5 mg by intramuscular injection ) and st and ard spinal anesthesia . Ten patients ( Gcontrol ) received preoperative and intraoperative passive thermal insulation . Ten patients ( Gpre+intra ) underwent preoperative and intraoperative active warming . Ten patients ( Gintra ) were only warmed intraoperatively . RESULTS After 45 min of preoperative warming , the patients in Gpre+intra had significantly higher core temperatures than did the patients in the unwarmed groups ( Gcontrol and Gintra ) before the anesthesia ( p < 0.05 ) but not at the beginning of surgery ( p > 0.05 ) . The patients who were warmed intraoperatively had significantly higher core temperatures than did the patients in Gcontrol at the end of surgery ( p < 0.05 ) . All the patients were hypothermic at admission to the recovery room ( T CORE < 36 degrees C ) . CONCLUSIONS Forty-five minutes of preoperative warming combined with intraoperative skin-surface warming does not avoid but minimizes hypothermia caused by spinal anesthesia in patients with midazolam premedication UNLABELLED Perioperative hypothermia poses a challenge because of its deleterious effects on patient recovery .  The current practice of applying two cotton blankets on patients during surgery is thought to be less ideal than using reflective insulation or forced-air warming . We studied 300 patients who underwent unilateral total knee replacement and were r and omized equally to three groups : ( a ) the two-cotton-blanket group , ( b ) the one-reflective-blanket with one-cotton-blanket group , and ( c ) the forced-air-warming with one-cotton-blanket group .  Tympanic temperature readings were taken before surgery in the induction room , on arrival at the recovery room , and at 10-min intervals until discharge from the recovery room . On arrival at the recovery room , the forced-air-warming group had significantly higher temperatures ( adjusted for sex , age , and patient 's induction room temperature ) of 0.577 degrees C + /- 0.079 degrees C ( 95 % confidence interval [ CI ] , 0.427 - 0.726 ; P < 0.001 ) and 0.510 degrees C + /- 0.08 degrees C ( 95 % CI , 0.349 - 0.672 ; P < 0.001 ) more than the reflective-blanket and two-cot-ton-blanket groups , respectively . The forced-air-warming group took a significantly ( P < 0.001 ) shorter time of 18.75 min ( 95 % CI , 13.88 - 23.62 ) to achieve a temperature of 36.5 degrees C in the recovery room as compared with 41.78 min ( 95 % CI , 36.86 - 46.58 ) and 36.43 min ( 95 % CI , 31.23 - 41.62 ) for the reflective-blanket and two-cotton-blanket groups , respectively . The reflective technology was less effective than using two cotton blankets , and the forced-air warming was most efficient in maintaining perioperative normothermia . IMPLICATION S Perioperative hypothermia has deleterious effects on patient recovery . We found in patients having knee surgery that reflective technology was less effective than using two cotton blankets , whereas active surface warming with the forced-air method was most effective in maintaining normothermia UNLABELLED Core hypothermia during the first hour after induction of general anesthesia results largely from an internal core-to-peripheral redistribution of body heat . This redistribution results from both central inhibition of tonic thermoregulatory vasoconstriction in the arteriovenous shunt and anesthetic-induced vasodilation . We therefore tested the hypothesis that acute administration of phenylephrine , a pure alpha-adrenergic agonist , reduces the magnitude of anesthetic-induced core-to-peripheral redistribution of body heat . Patients undergoing minor oral surgery were r and omly assigned to an infusion of 0.5 microgram.kg-1.min-1 phenylephrine i.v . or no treatment ( control ) . The phenylephrine infusion was started immediately before anesthesia was induced with 2.5 mg/kg propofol i.v . Subsequently , an 
    Output:
    
Forced air warming was effective in maintaining intraoperative normothermia when compared to passive warming , routine thermal care and no form of warming .
Forced air warming in pregnant women scheduled for caesarean delivery under regional anaesthesia  prevented maternal and foetal hypothermia .
In contrast , passive warming with tight elastic b and ages wrapped around the legs ( passive insulation ) in the same patient population had no significant benefits in preventing maternal hypothermia .
However , in arthroscopic knee surgery patients , forced air warming did not result in a decrease in the incidence of postoperative shivering indicating that it was not effective or feasible to extend active warming into recovery in this patient population .
Forced air warming  was effective than circulating water mattress in preventing hypothermia in patients who underwent repair of infrarenal aortic aneurysms .
Forced air warming  was effective against radiant warming in maintaining intraoperative normothermia in lengthier surgical procedures .Prewarming in different patient population s prevents redistribution hypothermia , especially after one hour of anaesthesia induction .
Intravenous and irrigating fluids warmed ( 38 - 40 ° C ) to a temperature higher than that of room temperature by different fluid warming devices ( both dry and water heated ) proved significantly beneficial to patients in terms of stable haemodynamic variables , and higher core temperature ( core T ) at the end of the surgery ( transurethral prostatectomy and orthopaedic surgery ) .
However , prewarming irrigation fluids in knee arthroscopy patients did not prove beneficial in maintaining normothermia .
Water garment warmer was significantly ( P < 0.05 ) effective than forced air warming in maintaining intraoperative normothermia in orthotopic liver transplantation patients .
Extra warming with forced air compared to routine thermal care was effective in reducing the incidence of surgical wound infections and postoperative cardiac complications , as well as shorten the length of hospital stay .
Passive warming with reflective heating blankets or elastic b and ages wrapped around the legs tightly were found to be ineffective in reducing the incidence or magnitude of hypothermia .
Low-flow anaesthesia with active forced air warming was effective in stabilising patient 's core T during surgical procedures when compared to low-flow anaesthesia alone or low-flow anaesthesia with passive insulation .
Phenylephrine i.v .
infusion result ed in a significantly less reduction in core T after first hour of anaesthesia and patients were warmer until the end of the surgery ( minor oral surgery ) .
Active warming with forced air warming units keeps all patients warmer in the intraoperative and postoperative periods .
Forced air warming compared with alternate forms of warming reduces the incidence of shivering and wound infections , increases thermal comfort and reduces morbid cardiac events .