Supplemental Table 1. Characteristics of studies performed in the perioperative setting with no induced hypothermia Author, Yr Intervention Setting Study Groups Summary

(1)

Supplemental Table 1. Characteristics of studies performed in the perioperative setting with no induced hypothermia Author, Yr Intervention Setting Study Groups

Summary

Shivering Measure

Results Trial

Characteristics^a Alfonsi,

2003 (23)

Forced-air warming system - Body

- Postoperatively

- Knee or shoulder arthroscopy - General anesthesia

1. Set at 43°C 2. Single cotton

blanket

Clinical assessment (3- point scale) and O₂ consumption since within 5 min of extubation

Lowered core temperature at shivering threshold in the treatment group (P<0.0001);

No difference in the duration of shivering (P=N/A)

1. RCT 2. 18 (9/9) 3. 6/7

Bock, 1998 (24)

Forced-air warming system - Upper body - Pre (30min)- &

Intraoperatively

- Major abdominal surgery

- General anesthesia

1. Set at 40-42°C 2. Passive protection

Determined postoperatively

Less shivering in the treatment group (P=N/A)

1. RCT 2. 40 (20/20) 3. 3/7

Horn, 2002 (25)

Forced-air warming system - Upper body - Pre (15min)- &

Intraoperatively

- Elective cesarean delivery

- Epidural anesthesia

1. Set at 43°C 2. Single cotton

blanket

4-point shivering scale during delivery

Less incidence of shivering in the treatment group (P<0.05)

1. RCT 2. 30 (15/15) 3. 6/7

Jackson, 1997 (26)

Forced-air warming system - Whole body - Postoperatively

(3hrs)

- Hypothermic patients

(<=35.9°C) after operation

1. Set at 42-46°C 2. Two standard cotton

blankets

Visual observation during the first three 15- min periods of the study

Less incidence of

shivering (P<0.05) for the periods of 15-30 min and 30-45 min, but not for 0- 15 min

1. RCT 2. 20 (10/10) 3. 3/7

Krenzischek , 1995 (27)

Forced-air warming system - Whole body - Intra- &

Postoperatively (2hrs)

- Vascular, thoracic, or abdominal surgery - Epidural or

general anesthesia

1. Aiming to maintain core temperature at or near 37°C 2. Warmed cotton

blankets

Shivering score during the postoperative period

Less incidence of shivering in the treatment group

1. RCT 2. 29 (15/14) 3. 5/7

Lennon, 1990 (28)

Forced-air warming system - Whole body - Postoperatively

- Hypothermic patients (<=35°C) after operation - Not described

1. Maximum

temperature of 43°C 2. Cotton blanket

warmed to 37°C

Recorded in the recovery room until discharge

Less incidence of shivering at 15 min and 45 min in the treatment group (P<0.05)

1. RCT 2. 30 (15/15) 3. 3/7 Mason, Forced-air - Roux-en-Y gastric 1. Set at 383°C 4-point shivering scale Lower shivering score in 1. RCT

(2)

1998 (29) warming system - Lower body - Intraoperatively

bypass with obese patients

2. Warmed cotton blankets

during the first 2 hours after surgery

the treatment group (P<0.05)

2. 64 (32/32) 3. 6/7 Mogera,

1997 (30)

Forced-air warming system - Whole body - Intraoperatively

- Elective intracranial surgery

1. Set at 36.5-38°C 2. Cotton sheet

Absent, mild, and severe based on

electrocardiographic artifacts and clinical observation at the end of surgery

Less incidence of shivering in the treatment group (P=N/A)

1. RCT 2. 30 (15/15) 3. 4/7

Pu, 2014 (31)

Forced-air warming system - Under body - Intraoperatively

- Open and laparoscopic gastrointestinal surgery

1. Set at maximum temperature of 41°C 2. A quilt

Assessed at the end of anesthesia

Less incidence of shivering (P=0.034)

1. RCT 2. 110 (55/55) 3. 4/7

Yoo, 2009 (32)

Forced-air warming system - Not clear - Intraoperatively

- Elective shoulder arthroscopic surgery

1. Set at 36-38°C 2. A cotton blanket

Recorded on arrival in the PACU

Less incidence of shivering (P=N/A)

1. RCT 2. 44 (22/22) 3. 4/7 Camus,

1993 (33)

Forced-air warming system + cotton blanket - Lower body - Intraoperatively

- Elective

abdominal surgery - General anesthesia

1. Set at 43°C + two cotton sheets 2. Set at 43°C

3. No warming process

electrocardiographic artifacts and clinical observation during recovery

Less incidence and duration of shivering (p<0.05)

1. RCT 2. 33 (11/11/11) 3. 4/7

Horn, 2012 (34)

Forced-air warming system + cotton blanket - Not described - Preoperatively

- Elective surgery - General

anesthesia,

1. Set at 44°C for 30 min

4. Passive insulation

4-point shivering scale in the postoperative care unit

Less incidence of shivering in the prewarmed groups (P<0.05)

1. RCT 2. 200

(50/43/52/55) 3. 5/7

Smith, 1994 (35)

Forced-air warming system + cotton blanket - Upper body - Intraoperatively

- Arthroscopic knee surgery

1. Set at 43.3±2.8°C + cotton blanket 2. Warmed cotton

blankets

Observed in the PACU Less duration of shivering in the treatment group (P<0.05);

No difference in the incidence of shivering (P>0.05)

1. RCT 2. 75 (38/37) 3. 5/7

(3)

Smith, 1994 (35)

Forced-air warming system + cotton blanket - Upper body - Intra- &

Postoperatively

- Arthroscopic knee surgery

1. Set at 43.3±2.8°C + cotton blanket 2. Warmed cotton

blankets

Observed in the PACU Less duration of shivering in the treatment group (P<0.05);

No difference in the incidence of shivering (P>0.05)

1. RCT 2. 52 (31/21) 3. 4/7

Vanni, 2003 (36)

Forced-air warming system + cotton blanket - Not described - Intraoperatively

- Elective

1. Body covered preoperatively and upper body covered intraoperatively, both set at 42 to 46°C + one cotton sheet.

2. Body covered intraoperatively, set at 42 to 46°C + one cotton sheet.

3. No special precautions were taken to avoid hypothermia

Less incidence of shivering in the treatment groups (P<0.01)

1. RCT 2. 30 (10/10/10) 3. 6/7

Chung, 2012 (37)

1. Forced-air warming system

2. Pre-warmed IV fluid

- Preoperatively (15min)

- Elective cesarean section

- Spinal anesthesia

1. IV fluid at room temperature + Upper body forced air- warming system, set at 43°C

2. Pre-warmed IV fluid (40°C) + Upper body forced air- warming system switched off 3. IV fluid at room

temperature + Upper body forced air- warming system switched off

5-point shivering scale during and after cesarean section

Significant difference among the three groups (P=0.035)

1. RCT 2. 45 (15/15/15) 3. 4/7

Butwick, Forced-air - Cesarean delivery 1. Set at 43°C Shivering scale of 0 to 4, No significant differences 1. RCT

(4)

2007 (38) warming system - Lower body - Intraoperatively

- Spinal anesthesia 2. Identical cover switched off

starting before initiating anesthesia for a

maximum of 135 min

in the incidence and intensity of shivering (P>0.05)

2. 30 (15/15) 3. 7/7 Fallis, 2006

(39)

Forced-air warming system - Upper body - Intraoperatively

- Spinal or epidural anesthesia

1. Set at 43°C 2. Warmed cotton

blankets

4-point shivering scale until exiting the OR

No significant difference (P>0.05)

1. RCT 2. 62 (32/30) 3. 6/7 Glosten,

1993 (40)

Forced-air warming system - Whole body - Preoperatively

(2hrs)

- Healthy volunteer - Epidural

anesthesia

Set at 38°C

Same subjects rested uncovered for 2 hours before epidural injection

Noted during anesthesia Less incidence of shivering when prewarmed (P=0.049);

Less duration of shivering when prewarmed

(P=0.005)

1. Crossover RCT 2. 7

3. 2/6

Camus, 1993 (33)

Electric warming blanket

- Lower body - Intraoperatively

- Elective

1. Set at 42-43°C 2. No warming process

Less incidence, intensity, and duration of shivering in the treatment group (p<0.05)

1. RCT 2. 22 (11/11) 3. 4/7

Camus, 1997 (41)

- Whole body - Intraoperatively

- Non-hemorrhagic abdominal surgery - General anesthesia

1. Set at 40°C 2. No warming unless

core temperature decreased to less than 35°C

Evaluated during recovery

1. RCT 2. 18 (10/8) 3. 3/7

Just, 1993 (42)

- Whole body - Preoperatively

(

≥

90min)

- Elective total hip arthroplasty - General anesthesia

1. Set at 42-43°C 2. A cotton sheet without other warming process

Evaluated in the recovery room

1. RCT 2. 16 (8/8) 3. 3/7

Yildirim, 2012 (43)

Electric warming pad

- Open

cholecystectomy - General anesthesia

1. Set at 37°C

Shivering score on scale of 0 to 4 in the recovery room

Less incidence of shivering in the treatment group (P=0.042)

1. RCT 2. 80 (40/40) 3. 5/7 Chakladar,

2014 (44)

Electric warming mattress

- Spinal, epidural, or general

1. Set at 40°C

Shivering scale of 0 to 3 No significant difference (P>0.05)

1. RCT 2. 116 (58/58) 3. 6/7

(5)

anesthesia Sharkey,

1987 (45)

Radiant heat exposure - Postoperatively

- Patients who shivered after cesarean section or postpartum tubal ligation - General, spinal, or

epidural anesthesia

1. Suspended heating lamps over sternum for up to 30 min 2. Pre-warmed blanket

EMG recording of shivering in the post operative recovery area

Less incidence after 10 min of intervention and less duration of shivering in the treatment group (p<0.001)

1. RCT 2. 30 (15/15) 3. 5/7

Sharkey, 1987 (45)

Radiant heat exposure - Postoperatively

- Patients who shivered after cesarean section or postpartum tubal ligation - General, spinal, or

epidural anesthesia

Suspended heating lamps over sternum;

Lamps on for 3 min, then off for 2 min, followed by second cycle of repetition

EMG recording of shivering in the post operative recovery area

Less incidence of shivering when lamps turned on. (P=N/A)

1. One group repeated

treatment design 2. 30

3. 3/6

Ihn, 2008 (46)

1. Water- circulating mattress 2. Forced-air

warming system - Intraoperatively

- Total abdominal hysterectomy - General anesthesia

1. Circulating water mattress, set to 41°C 2. Whole body forced-

air warming, set at 43°C

3. Upper body forced- air warming, set at 43°C

5-point shivering scale after emergence from anesthesia

Less incidence and intensity in forced-air warming groups compared to water circulating mattress group (P<0.05)

No significant difference between group 2 and 3 (P>0.05)

1. Randomized trial 2. 90 (30/30/30) 3. 4/7

Kim, 2014 (47)

1. Water- circulating mattress 2. Forced-air

warming system

- Intraoperatively

- Total knee arthroplasty - Spinal anesthesia

1. Set at 41°C 2. Upper body, Set at

43°C

Shivering scale of 0 to 5 during surgery and in the recovery room

Less incidence and severity of shivering in forced-air warming group compared to water circulating mattress group (P<0.05)

1. Randomized trial 2. 46 (23/23) 3. 3/7

Janicki, 2001 (48)

1. Water- circulating garment

- Open abdominal procedures - General anesthesia

1. Whole body water- circulating garment, set at 36.8°C

Observed at the PACU or surgical intensive care unit

No significant differences in the incidence (P>0.05)

(6)

2. Forced-air warming system - Intraoperatively

2. Upper body forced air blanket, set at 43°C

Leung, 2007 (49)

1. Electric heating pad

2. Forced-air warming system - Intraoperatively

- Elective laparotomy - General anesthesia

1. Electric heating pad placed on the operating table, set at 39°C

2. Upper body forced- air warming, set at 43°C

Observed in the post- anesthetic room

No difference in the incidence (P>0.05)

Weyland, 1994 (50)

1. Radiant heat exposure 2. Electric heating

blanket - Postoperatively

- Patients remained intubated and continued sedation - General anesthesia

1. Whole body heating with radiant heater, at a distance of 75cm from the chest 2. Whole body electric

heating blanket 3. Standard hospital

blanket

Documented according to a scale from 0 to 4

Less incidence in radiant heater group compared to electric blanket

(P<0.05)

1. RCT

2. 35 (12/12/11) 3. 3/7

Casati, 1999 (51)

Forced-air warming system - Intraoperatively

- Total hip arthroplasty - Combined spinal-

epidural anesthesia

1. Both arms covered, set at 38°C 2. Both legs covered,

set at 38°C

Recorded in the recovery room

1. RCT 2. 48 (24/24) 3. 4/7

Camus, 1996 (52)

Warmed IV fluid (Hotline) - Intraoperatively

- Major abdominal surgery

1. Warmed IV fluids (37°C)

2. IV fluids at room temperature

1. RCT 2. 18 (9/9) 3. 4/7

Hong-xia, 2010 (53)

- Abdominal surgery

1. Warmed IV normal saline (37°C) 2. IV normal saline at

room temperature

4-point shivering scale (0 to 3) during recovery

Less incidence of shivering at grade >=2 in the treatment group (P<0.01)

1. RCT 2. 30 (15/15) 3. 4/7 Kim, 2014

(54)

Warmed IV fluid (warmed cabinet)

- Ambulatory urological surgery - General anesthesia

1. Pre-warmed IV fluids (41°C) 2. IV fluids at room

Graded into 0 to 2 in the PACU

1. RCT 2. 53 (27/26) 3. 6/7

(7)

temperature No difference in the incidence of grade 2 shivering

Okeke, 2007 (55)

Warmed irrigation fluid + Warmed IV fluid - Intraoperatively

- Transurethral resection of the prostate gland (TURP)

- Spinal anesthesia

1. Warmed irrigation fluid and warmed IV fluids at 38°C 2. Warmed irrigation

fluid at 38°C along with IV fluid at room temperature 3. Irrigation and IV

fluids at room temperature

Observed during the procedure

(Out of the patients who felt cold) Less incidence of shivering in the treatment groups (P<0.001)

1. RCT

2. 120 (40/40/40) 3. 2/7

Jorgensen, 2000 (56)

Warmed IV fluid - Pre (15min)- &

Intraoperatively (20min)

- Spinal anesthesia

1. Warm IV saline (37°C)

2. Cold IV saline (21°C)

4-point scale before delivery

No significant difference in the incidence and intensity of shivering (P>0.05)

1. RCT 2. 113 (57/56) 3. 6/7

Smith, 1998 (57)

Intraoperative intervention under - Elective

gynecological surgery

1. IV fluid warmed at 38-39°C

2. IV fluid at room temperature (21°C)

Recorded as none, mild or severe in the PACU

No significant difference in the incidence and intensity of shivering (P>0.05)

1. RCT 2. 38 (18/20) 3. 4/7

Woolnough, 2009 (58)

IV fluid warming system (Warming cabinet or Hotline)

- Intraoperatively

- Combined spinal and epidural anesthesia

1. IV fluid warmed at 45°C via a Hotline fluid warmer 2. IV fluid heated in a

warming cabinet set at 45°C

3. IV fluid at room temperature

3-point scale after the anesthesia

No significant difference in the incidence of shivering (P>0.05)

1. RCT 2. 75 (25/25/25) 3. 7/7

Neoh, 1989 (59)

Warmed irrigation fluids - Intraoperatively

- Transurethral resection of the prostate

- Spinal anesthesia

1. Irrigation fluids between 25.5 and 33°C

2. Irrigation fluids between 21.5 and 23°C

Observed during the procedure

1. RCT 2. 24 (13/11) 3. 3/7

(8)

Oh, 2014 (60)

Warmed irrigation fluid - Intraoperatively

- Arthroscopic shoulder surgery - General anesthesia

1. Irrigation fluids warmed to 36°C 2. Irrigation fluids of

room-temperature

Observed in PACU No significant difference in the incidence of shivering (P=0.347)

1. RCT 2. 72 (36/36) 3. 4/7 Hamza,

2005 (61)

Heated

humidified (HH) intra-peritoneal CO₂

- Intraoperatively

- Roux-en-Y gastric bypass with obese patients

1. Warmed (37°C) and humidified (95%

relative humidity) intraperitoneal CO₂ insufflation gas 2. Room temperature

intraperitoneal insufflation gases

Observed in the PACU Less incidence of shivering in the treatment group (P=0.03)

1. RCT 2. 46 (23/21) 3. 5/7

Frank, 2000 (62)

HH inspiratory O₂

- Postoperatively (90min)

- Abdominal surgery

1. Warmed (42°C) humidified high- flow O₂therapy by nasal cannula 2. Anhydrous room

temperature O₂ delivered by face mask

4-point shivering score No significant difference in the incidence of shivering (P=0.67)

1. RCT 2. 30 (15/15) 3. 4/7

Goldberg, 1992 (63)

1. HH 2. Heat and

moisture exchanger (HME) - Intraoperatively

- Lower abdominal procedures - General anesthesia

1. HH, set at 37°C 2. HME

3. No warming device

Recorded in the post- anesthesia care unit

No difference between HH and HME (P>0.05)

1. RCT

2. 51 (14/21/16) 3. 4/7

Linko, 1984 (64)

1. HH 2. HME

- Intraoperatively

- Major intra- abdominal surgery - General anesthesia

1. HH to 40°C 2. HH to 37°C 3. HME

Postoperative shivering score

No difference between groups (P>0.05)

1. Randomized trial 2. 30 (10/10/10) 3. 3/7

Patel, 1996 (65)

1. Hotline 2. Flotem IIe - Intraoperatively

- Major elective orthopedic or gynecologic surgery

1. Received IV fluid warmed with Hotline device 2. Received IV fluid

warmed with Flotem IIe device

Recorded as none, mild or severe in the recovery room

Less incidence and less intensity of shivering in Hotline group. (P=0.04)

Buggy &

Hughes,

Space blanket -

≥

60% of body

- Elective orthopedic and

1. Space blanket placed between gown and

Observed in the recovery room

Less incidence of shivering in the treatment

1. RCT 2. 68 (34/34)

(9)

1994 (66) surface

- Intraoperatively

plastic surgery on the limbs

surgical drapes 2. Routine surgical

drapes

group (P < 0.001)

3. 3/7

Buggy &

Gardiner, 1995 (67)

Space blanket - Whole body - Intraoperatively

- Delivery - Epidural

anesthesia

1. Space blanket placed between gown and cotton sheet 2. Standard cotton

covering

4-point scale during labor

Reduction in the intensity in the treatment group (P<0.05)

1. RCT 2. 50 (25/25) 3. 4/7 Observed within 60 min

of receiving the epidural analgesia

No significant difference in the incidence of shivering between two groups

(P>0.05) Koeter,

2013 (68)

Space blanket - Whole body - Pre- &

Postoperatively

- Total knee or hip replacement - General or spinal

anesthesia

1. Space blanket 2. No covering

4-point shivering scale in the ward before and after surgery

No difference (P=N/A) 1. RCT 2. 58 (29/29) 3. 5/7 Sun, 2004

(69)

Elastic bandages - Lower body - Intraoperatively

- Epidural anesthesia

1. Wrapped with tight elastic bandages 2. Loosely covered with no tension by elastic bandages

Observed until delivery No significant difference in the incidence of shivering (P=0.61)

1. RCT 2. 60 (30/30) 3. 4/7

Yeh, 2012 (70)

Electro- acupuncture - Preoperatively

(30min)

- Elective

ureteroendoscopy surgery

- Spinal anesthesia

1. Inserted acupuncture needle with electro- stimulation for 30 minutes

2. Placebo acupuncture

Shivering score (0 to 4) during surgery

Less incidence and intensity of shivering in the treatment group (P=0.003)

1. RCT 2. 80 (40/40) 3. 7/7

Kurz, 1995 (71)

Forced-air warming system + Warmed fluid - Upper body - Intraoperatively

- Elective colon surgery

1. Set at 40°C + Fluid at 37°C

2. Routine thermal management

3-point scale postoperatively

Less shivering in the treatment group (P=N/A)

1. RCT 2. 74 (35/39) 3. 6/7

Zhao, 2005 (72)

Forced-air warming system + Warmed fluid - Lower body - Intraoperatively

- Elective

1. Set at 42-43°C + Fluid at 39°C 2. A cotton sheet

Evaluated as absent, mild, medium, and severe in PACU

Less incidence of shivering (P<0.01)

1. RCT 2. 40 (20/20) 3. 4/7

Bredahl, 1995 (73)

1. Radiant heat exposure

- Elective major surgery

1. Radiant heater mounted 65cm

Shivering score during the 2h study period

1. Randomized trial 2. 30 (15/15)

(10)

2. Space blanket - Postoperatively

- General (+epidural) anesthesia

above the patient 2. Space blanket, in addition to three cotton blankets

3. 3/7

Patel, 1997 (74)

1. Space blankets + IV fluid warming system (Hotline) 2. Forced-air

warming system - Intra- (+post)

operatively

- Elective gynecological, orthopedic, or general surgery - General anesthesia

1. 75-85% of body surface warmed with space blankets intra- and post-operatively + Warmed IV fluids, set at 42°C

2. Upper-body forced- air blanket, set at 43°C, intraoperatively + IV fluid, set at 21°C

Recorded as absent, mild, or severe in the recovery room

a1. Study design; 2. Sample size in the format of “total number of participants (number in group 1, number in group 2, …)”; 3. Study quality score in the format of “score of the study/maximum score”

RCT: randomized controlled trial, PACU: post anesthesia care unit, OR: operating room, EMG: electromyography, HH: heated humidifier, HME: heat and moisture exchanger