In the fixed effect model , the warming group had significantly less pain and lower incidence of wound infection , compared with the no-warming group .
In the r and om effect model , the warming group was also associated with lower risk of post-anesthetic shivering .
Both in the r and om and the fixed effect models , the warming group was associated with significantly less blood loss .
Perioperative warming of surgical patients is effective in reducing postoperative wound pain , wound infection and shivering .
Systemic warming of the surgical patient is also associated with less perioperative blood loss through preventing hypothermia-induced coagulopathy .
OBJECTIVE The objective of this review was to systematic ally analyze the trials on the effectiveness of perioperative warming in surgical patients .
Aggressive Warming Reduces Blood Loss During Hip Arthroplasty
We evaluated the effects of aggressive warming and maintenance of normothermia on  surgical blood loss and allogeneic transfusion requirement . We r and omly assigned 150 patients undergoing total hip arthroplasty with spinal anesthesia to  aggressive warming ( to maintain a tympanic membrane temperature of 36.5 ° C ) or conventional warming ( 36 ° C ) . Autologous and allogeneic blood were given to maintain a priori design ated hematocrits . Blood loss was determined by a blinded investigator based on sponge weight and scavenged cells ; postoperative loss was determined from drain output . Results were analyzed on an intention-to-treat basis . Average intraoperative core temperatures were warmer in the patients assigned to aggressive warming ( 36.5 ° ± 0.3 ° vs 36.1 ° ± 0.3 ° C , P < 0.001 ) . Mean arterial pressure was similar in each group preoperatively , but was greater intraoperatively in the conventionally warmed patients : 86 ± 12 vs 80 ± 9 mm Hg , P < 0.001 . Intraoperative blood loss was significantly greater in the conventional warming ( 618 mL ; interquartile range , 480–864 mL ) than the aggressive warming group ( 488 mL ; interquartile range , 368–721 mL;P = 0.002 ) , whereas postoperative blood loss did not differ in the two groups . Total blood loss during surgery and over the first two postoperative days was also significantly greater in the conventional warming group ( 1678 mL ; interquartile range , 1366–1965 mL ) than in the aggressively warmed group ( 1,531 mL ; interquartile range , 1055–1746 mL , P = 0.031 ) . A total of 40 conventionally warmed patients required 86 units of allogeneic red blood cells , whereas 29 aggressively warmed patients required 62 units ( P = 0.051 and 0.061 , respectively ) . We conclude that aggressive intraoperative warming reduces blood loss during hip arthroplasty . Implication s Aggressive warming better maintained core temperature ( 36.5 ° vs 36.1 ° C ) and slightly decreased intraoperative blood pressure . Aggressive warming also decreased blood loss by approximately 200 mL. Aggressive warming may thus , be beneficial in patients undergoing hip arthroplasty
In the fixed effect model , the warming group had significantly less pain and lower incidence of wound infection , compared with the no-warming group .
In the r and om effect model , the warming group was also associated with lower risk of post-anesthetic shivering .
Both in the r and om and the fixed effect models , the warming group was associated with significantly less blood loss .
Perioperative warming of surgical patients is effective in reducing postoperative wound pain , wound infection and shivering .
Systemic warming of the surgical patient is also associated with less perioperative blood loss through preventing hypothermia-induced coagulopathy .
OBJECTIVE The objective of this review was to systematic ally analyze the trials on the effectiveness of perioperative warming in surgical patients .