C2RISK FACTORS NON-PHARMACOLOGICAL

Study detailsPatient detailsFactors adjusted forAnaesthesia/surgeryFurther details
Abelha 2005; prospective cohort study; country portugal; total number of patients: 185Age: 66.0 y (sd 12.6), range 25 to 94; ASA grade ASA I 3%, ASA ii 39%, ASA III 49%, ASA IV 10%; temperature measured at tympanic membrane; some had warming mechanismsMagnitude of surgery, IV crystalloids, preop patient temp, saps ii + adjusted for: anaesthesia type, anaesthesia duration, temperature monitoring, FAW, packed erythrocytes. Univariate: age, gender, body weight, BMI, ASA, emergency, IV colloids, plasmaType of anaesthesia: mixed general/regional/combined; type of surgery: non-cardiac; theatre temperature 20–22°C(not adjusted for)Multivariate analysis only contained those with p<0.1 in univariate analysis. 29/185 patients died. Preop ward temperature 36.37 (sd 0.49); range 35.00 to 38.60°C. 22/185 (12%) had temperature monitoring; 81/185 (44%) had FAW.
Baker 1995; prospective cohort study; country Canada; total number of patients: 56Age: 59.9 (sd 11.9); ASA grade: not stated; temperature measured at pulmonary artery; no FAW, but warmed blankets and blood warmedAge, gender, weight, height, history of previous cardiac surgery, pre- bypass temperature, time on cpb, fluid balance on cpb, type of surgery, nitroglycerin in theatre, airway humidifier, alpha agonists, volume warmed IV fluids, volume of unwarmed fluidsType of anaesthesia: general; type of surgery: cardiac normothermia cpb; theatre temperature not statedPatients having elective/urgent cardiac surgery under normothermic bypass. No FAW, but warmed blankets used at nurse’s discretion; blood kept at 37°C, but IV fluids not warmed. Premed morphine/perphenazine. 15 had IPH.
Closs 1986; prospective cohort study; country UK; total number of patients: 31Age: 53.6 y (cholecystectomy) and 72 y (fnf); ASA grade: not stated; temperature measured at aural; no warming mechanisms statedMultivariate analysis only recorded r and r2 not coefficients or p-values. Adjusted for age, theatre temperature, time spent in recovery, triceps skinfold thickness or body densityType of anaesthesia: not stated; type of surgery: abdominal and orthopaedic; theatre temperature not stated (even though in regression analysis)Temperature not measured during surgery or in immediate postoperative period because of problems of access. Cholecystectomy; n=17) and fractured femur; n=14)
Danelli 2002; RCT study; country Italy; total number of patients: 44Age: mean 64 and 62 y (sd 8); range 18 minm to 75 max); ASA gradeI–II; temperature measured at bladder; no warming devices but fluids warmedRCT, comparable at baseline for age, gender, weight, height, blood loss, crystalloid infusion. Duration of surgery was significantlty longer in the laparoscopic group (mean difference 1.1 h)Type of anaesthesia: combined general/regional; type of surgery: abdominal; theatre temperature 21–23°C, laminar flow, rel humidity 40–45%Colorectal resection, duration 255 and 180 min (medians). Obese patients excluded. Premed with midazolam. Ga induction thiopental/fentanyl/atracurium; maintained isoflurane. Epidural block up to t4 with ropivacaine. Infused solns warmed to 37°C.
El-gamal 2000; prospective cohort study; country Egypt; total number of patients: 40Age: 2 groups: 33 y (sem 2); 20–40 & 67 (sem 2); 60–75y; ASA gradeI–II; temperature measured at tympanic membrane; no warming mechanisms stated2 selected cohorts, 20 aged 20–40y, 20 aged 60–75. Following held constant: ASA I–II, type of surgery (lower extremity orthopaedic), type of anaesthetic (GA). Comparable at baseline for bmi, duration of surgery, IV fluid volume; preop core temperatureType of anaesthesia: general; type of surgery: orthopaedic; theatre temperature 25.6 or 25.9°C(SEM 0.3); range 24.2 to 28.5Exclusions cardiac/pulmonary disease, thyroid disorders, raynaud’s disease, dysautonomia, preoperative fever. Duration of surgery 1.7–1.8 h (sem 0.08). IV crystalloids given at room temperature
Flores-maldonado 1997; prospective cohort study; country México; total number of patients: 130Age: 5 to 90 y (mean 42 sd20); ASA grade I: 50%; ASA II: 40%; ASA III/IV 10%; temperature measured at tympanic membrane; no warming mechanisms statedAge, gender, theatre temperature, duration of surgery, magnitude of surgery, blood transfusion, type of anaesthesia x3Type of anaesthesia: mixed general/regional groups; type of surgery: mixed; theatre temperature mean 22.9 (sd 1.2)°CPatients with fever, head or neck surgery and ear or upper respiratory tract infection not admitted into follow up. Emergency (35%) and elective. 53 patients had IPH. 19% had ‘miscellaneous’ anaesthesia. Initial temp not stated.
Frank 1992; RCT study; country USA; total number of patients: 97Age: 35 to 94y; mean 64.5, sd 1.1; ASA grade: not stated or considered; temperature measured at sublingual reliable; no wd but fluids warmedAnova/multiple regression adjusted for
  1. age
  2. type of anaesthesia
  3. theatre temperature, duration in operating room, volume of IV crystalloid, blood transfusion units.
Also included were 3 interaction terms: (i) x (ii), (i) x (iii), (ii) x (iii)
Type of anaesthesia: RCT general/epidural; type of surgery: vascular; theatre temperature mean 20.9 °C (SD 0.13); range 18.7 to 22.9°CAssignment to theatres based on scheduling rules/availability. Different analgesia for general (morphine pca) and epidural (fentanyl) anaesthesia. All had im midazolam premed. Lower extremity vascular bypass grafting. Preop temp not stated. Althought this was an RCT for type of anaesthesia, we assessed it as a cohort study because the other variables were assigned in non-random way.
Frank 1994; RCT study; country USA; total number of patients: 30Age: median 62 y (48–70); ASA gradeI–II; temperature measured at tympanic membrane; no warming devices but fluids warmedStratified RCT (on surgeon); also analysed as subgroups by age. Baseline comparable for age, body weight, duration surgery, theatre temp, PACU temperature, blood transfusion. Not comparable: crystalloid admin (significantly higher in GA)Type of anaesthesia: randomised to epidural/general; type of surgery: urology; theatre temperature 21.7 (sem 0.4) ea and 22.0 (sem 0.4) gaRadical prostatectomy for prostate cancer, all had midazolam on arrival in or. Pre-induction IV ringers at room temp, then fluids warmed to 37°C. Gases warmed to 38°C& humidified. No warming devices. All patients had epidural catheter. PACU temp 23.3°C. (sem 0.3)EA; 23.0°C (sem 0.3) GA. No patient had Raynauds disease, preop fever, thyroid disorder.
Frank 2000; prospective cohort study; country USA; total number of patients: 44Age: 57 years (SD 7) range 47–67; ASA grade not stated or considered; temperature measured at tympanic membrane; no warming devices but fluids warmedAge, duration of surgery, theatre temperature, body mass, %body fat, height of spinal block (+univariate bmi)Type of anaesthesia: spinal; type of surgery: urology; theatre temperature mean 20.9°C (sd 0.13) range 18.7 to 22.9.All patients male undergoing radical prostatectomy under spinal anaesthesia (midazolam + 18–20 mg bupivacaine/20 mcg fentanyl). Regression with backward elimination. Preop temperature 37°C.
Hendolin 1982; RCT study; country Finland; total number of patients: 38Age: GA 66.6y (SD6.6); EA 70.9 (SD8.9); ASA grade mean 2.3 or 2.6 (SD 0.6); temperature measured at aural and nasopharyngeal; wd not stated but blood warmedRCT. Baseline comparability age, weight, height, bmi, ASA. Factors kept constant: type of surgery, duration of surgeryType of anaesthesia: randomised to epidural/general; type of surgery: urology; theatre temperature 24°C; rel humidity 40–55%Retropubic prostatectomy, all had diazepam premedication 45 min preop. GA: induction thiopentone; 70% N20/O2 + pethidine. Ventilator 10 ml/kg. EA at 3rd lumbar vertebra (up to t5); butanilicaine. Blood warmed. Half had polygeline. Sig diff in periop blood loss. Preoperative temperature 36.2°C (SEM 0.1). Note that nasopharyngeal temperature measurement is not thought to be very accurate.
Hind 1994a; prospective cohort study; country UK; total number of patients: 30Age: 51.43 y (SD 12.01); range 37 to 76; ASA grade not stated; temperature measured at oesophageal; no warming mechanisms stated1st of 2 multivariate analyses that fitted the data. Factors included: age, theatre temperature, body fat index, IV fluids, total blood loss (from univariate correlations). Excluded: surgery duration, theatre humidity. Constant: type of anaesthesia.Type of anaesthesia: general; type of surgery: abdominal; theatre temperature 21.3°C (SD 1.2); 19.6–23.3. Rh: 56% (4); 50–65All patients female and surgery was in afternoon. Elective gynaecological surgery. GA: induction: omnopon/scopolamine; maintenance: thiopentone/suxamethonium/vecuroniu m/isoflurane/augmentin. Skin prep prewarmed (38–40°C), abdominal packs (40°C) duration of surgery 1–2h. Significant correlations found between age and theatre temperature, body fat, IV fluids, blood loss. Body fat correlated with theatre temperature.
Hind 1994b; prospective cohort study; country UK; total number of patients: 30Age: 51.43 years (SD 12.01); range 37 to 76; ASA grade not stated; temperature measured at oesophageal; no warming mechanisms stated2nd of 2 multivariate analyses that fitted the data. Factors included: theatre temperature, body fat index, IV fluids, total blood loss (from univariate correlations). Excluded: surgery duration, theatre humidity. Constant: type of anaesthesia.Type of anaesthesia: general; type of surgery: abdominal; theatre temperature 21.3°C(SD1.2); 19.6–23.3. Rh: 56% (4); 50–65All patients female and surgery was in afternoon. Elective gynaecological surgery. Ga: induction: omnopon/scopolamine; maintenance: thiopentone/suxamethonium/vecuronium/isoflurane/augmentin. Skin prep prewarmed (38–40°C), abdominal packs (40°C) duration of surgery 1–2h. Significant correlations found between age and theatre temperature (high correlation), body fat, IV fluids, blood loss. Body fat correlated with theatre temperature.
Kasai 2002; case control study; country Japan; total number of patients: 400Age: 63 (SD11); ASA gradeI–II; temperature measured at tympanic membrane; circulating water mattress 38 °C + warmed fluidsAge, height, weight, gender, preop systolic bp, preop core temperature, preop heart rateType of anaesthesia: combined general/regional; type of surgery: abdominal; theatre temperature 22 to 24°CCases >36.0°C; controls <35.0°C. Patients excluded if had blood transfusion or CV drugs for hypotension. Preop temp 36.7 )°C (SD 0.6.
Kitamura 2000; prospective cohort study; country Japan; total number of patients: 27Age: 59 and 62 years (SD12) (data given by sugroup); ASA grade: not stated; temperature measured at tympanic membrane; no warming devices2 cohorts, diabetic & controls, divided into young and old controls, & diabetic neuropathy positive or not. All groups comparable for age, bmi, IV fluid rate, surgery duration, ambient temp. Constant: type of anaesthesia. Sig diff for diastolic bp in tiltType of anaesthesia: general; type of surgery: abdominal; theatre temperature 23°CUnclear how cohorts selected. Patients with bmi > 28% excluded. No premeds. Induction fentanyl/propofol; maintenance 70% N20/isoflurane; IV fluids not warmed (10–15 ml/kg/h). Patients had FAW after study. 70–90% operations were >2h. No blood transfusion.
Kongsayearseepong 2003; prospective cohort study; country Thailand; total number of patients: 184Age: 15–93 years; ASA grade 19% ASA I; 55% ASA II; 26% ASA > II; temperature measured at tympanic membrane; some had active warmingAge, body weight, preop body temp, ASA, diabetic neuropathy, emergency surgery, magnitude of surgery, temp monitoring used, type of anaesthesia, IV fluid, duration of surgery, ambient temp (+ univariate: gender, FAW, duration of anaesthesia)Type of anaesthesia: mixed general/regional/combined; type of surgery: non-cardiac; theatre temperature mean 19.5 to 20.6°C(SD 1.9)Patients <15y/hyperthermic excluded. 21% <41y; 47% 41–70y; 32% >70y. Multivariate analysis only contained those with p<0.2 in univariate analysis. 11/184 patients died. Preop temperature 37.0 (sd 0.7) range 34.5 to 39.3°C. 53/184 (29%) had temperature monitoring; 90/184 (49%) had FAW.
Kurz 1995; prospective cohort study; country Austria; total number of patients: 40Age: mean 59 years (SD 14), range 26–79 y; ASA gradeI–II; temperature measured at oesophageal; no wd but fluids warmedMultivariate included gender, height, weight, % body fat, surface area and weight/surface area ratio. Type of surgery comparable for different size patients. Type of anaesthesia constant. No consideration taken of age or ASA grade.Type of anaesthesia: general; type of surgery: abdominal; theatre temperature maintained at 21.0°C(SD 0.4)Elective colon surgery; mean duration of surgery 3.8 h (SD1.3). Irrigation fluids warmed to body temperature, but no warming devices or fluid warmers. GA: induction thiopental/fentanyl/vercuronium; maintenance isoflurane/60%n2o/o2
Lau 2001; prospective cohort study; country China (Hong Kong); total number of patients: 18759Age: 13% <15y; 62% 15–64; 24% >65; ASA grade I:52%; ASA II:33%; ASA III 8%; ASA IV 2%; ASA V:0.3%; not identified 4%; temperature measured at not stated; warming mechanism not statedAge, ASA grade, type of anaesthesia, hospital. All of these were categorical variables.Type of anaesthesia: mixed general/regional/combined; type of surgery: mixed; theatre temperature not statedOnly for patients having surgery greater than 2 h duration. All 23 public hospitals in Hong Kong June/July 1998. 13.4% patients were <15y. 69% elective. 45% major surgery; 29% intermediate. Theatre temperature, warming devices not mentioned.
Mizobe 2005; RCT study; country Japan; total number of patients: 16Age: 20 to 60 y; ASA gradeI–II; temperature measured at oesophageal; no warming mechanisms statedRCT. Comparable at baseline for age, gender, weight, height, arterial pressure, heart rate, core temperatureType of anaesthesia: combined general/regional; type of surgery: abdominal; theatre temperature 24°C; rel humidity 40%Positive end expiratory pressure (peep) 10 cm H2O vs zero end expiratory pressure (zeep). Lower abdominal surgery. Induction: propofol/vecuronium bromide; maintained: isoflurane/66%n2o/o2.
Morris 1971; prospective cohort study; country USA; total number of patients: 22Age: mean 53 y (23 to 85); ASA grade; temperature measured at oesophageal; no warming mechanisms statedSub group analysis for age, theatre temperature, operative site and fluids infused. No significant difference in age or volume of fluids infused or site of op between lower and higher temperature theatres. Type of anaesthesia constant; surgery >2h.Type of anaesthesia: general; type of surgery: abdominal; theatre temperature cool theatre 18–21°C; warm theatre 21–24°CAll operations lasted >2h and evaluated during 0–2h. Intraabdominal. Premed varied. Ga: induction thiamylal/succinylcholine. Maintenance IV narcotic/N20 (2–4l/m)/O2(2l/m). Mean preop temperatures 36.9°C(SD 0.2)
Nakajima 2002; RCT study; country Japan; total number of patients: 16Age: mean 47 to 52 y (range 20–60); ASA gradeI–II; temperature measured at tympanic membrane; no warming mechanisms statedRCT, comparable at baseline for age, gender, height, weight, heart rate, arterial pressure, theatre temperature, fluids, sensory block, pre-induction temperatureType of anaesthesia: combined general/regional; type of surgery: abdominal; theatre temperature mean 23.9 to 24.2°C (SD 0.4); rel humidity 40%Open lower abdominal surgery (colorectal or gynae). None obese. All fasted for 8h, am operations; positioned after 10 min. In theatre 30 min before induction. GA: propofol induction, isoflurane/66%N2O/O2; epidural: bupivacaine, median T9 or T10 (T7–T12)
Nguyen 2001; RCT study; country USA; total number of patients: 101Age: mean 43 to 48 years (SD 8); ASA grade not stated; temperature measured at tympanic membrane; all had FAW but fluids not warmedType of anaesthesia: general; type of surgery: abdominal; theatre temperature 20 to 22°CGastric bypass. Stratified into two BMI groups: 40–49 kg/m2 and 50–60 kg/m2. All patients obese and <60y. All patients had compression sleeves and thigh high antiembolic stockings. Midazolam premed; induction: pentothal+succinylcholine; fentanyl/isoflurane oral temperatures preoperatively; oesophageal intraoperatively and tympanic membrane postoperatively.
Roberts 1994; retrospective cohort study; country USA; total number of patients: 77Age: mean 51 years; ASA grade; temperature measured at oesophageal; no warming devicesUnivariate analysisType of anaesthesia: general; type of surgery: urology; theatre temperature not statedPercutaneous nephrolithotomy. Passive warming (hat, inluding plastic seal), room temperature fluids. Mean core temperature at induction 36.7°C.
Steinbrook 1997; RCT study; country USA; total number of patients: 13Age: GA: 47 years (SD 5); combined: 38 (SD 13); ASA gradeI–III (IV and above excluded); temperature measured at oesophageal; no warming devicesRCT. Comparable at baseline for height, blood loss, opioids, preop temperature. Not comparable for age, weight, intraoperative fluids (may not be significant difference).Type of anaesthesia: mixed; type of surgery: abdominal; theatre temperature 20 to 22°CAll had premedication midazolam/fentanyl. Major intraabdominal surgery. Fluids not warmed. FAW or fluid warming given if temperature <35°C. May be confounded by this process.
Stewart 1998; prospective cohort study; country Australia; total number of patients: 107Age:; ASA grade; temperature measured at bladder; all had active warmingAnovaType of anaesthesia: mixed; type of surgery: abdominal; theatre temperature 22°CThis study was not considered further because it was confounded: all having open surgery had combined gen/epidural & all receiving laparoscopic surgery had general anaesthesia. All patients were warmed with a FAW set at 40°C and IV fluids were warmd
Vorrakitpokatorn 2006; prospective cohort study; country Thailand; total number of patients: 128Age: 48.9 years (SD 13.54); 12.5% >65 years; ASA grade I 59%; ASA II: 31%; ASA III 9%; temperature measured at tympanic membrane; no warming mechanisms statedAge, duration of surgery, volume of irrigation fluid, blood transfusion units. Constant: type of anaesthesia.Type of anaesthesia: general; type of surgery: urology; theatre temperature not statedAge >18y; all patients had first time surgery for percutaneous nephrolithotomy. All patients had antibiotics. 56% had IPH intraoperatively. Some patients appeared to have FAW.
Yamakage 2000; prospective cohort study; country Japan; total number of patients: 60Age: 58 years (SD10); ASA gradeI–II; temperature measured at rectal; no warming devices but fluids warmedType of anaesthesia held constant at baseline: duration of anaesthesia effectively constant because considered at particular times less than duration of operation. Age partly adjusted in body fat calculator.Type of anaesthesia: general; type of surgery: orthopaedic; theatre temperature 23.2°C(SD 0.7); rel humidity 31% (sd 8%)Surgery on lumbar vertebrae (e.g. Disk herniation, spondylolisthesis); prone position. Premed pentobarbital. GA: induction thiamylal/vercuronium; maintenance isoflurane/N20/O2; fluids warmed to 37°C. Initial temperature 37.1°C(SD 0.4).

From: APPENDIX C, CHARACTERISTICS OF INCLUDED STUDIES

Cover of The Management of Inadvertent Perioperative Hypothermia in Adults
The Management of Inadvertent Perioperative Hypothermia in Adults [Internet].
NICE Clinical Guidelines, No. 65.
National Collaborating Centre for Nursing and Supportive Care (UK).
Copyright © 2008, National Collaborating Centre for Nursing and Supportive Care.

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