2

Citation Design/Method Sample/Setting Major Variables studied and their

definitions

Measurement and Data analysis

Findings Results Conclusions Appraisal: Worth to Practice

1. Oh EJ, et al.

This is an RCT, prospective parallel-group; adult LDLT; n=40 (20/20); 30-min forced- air prewarming vs no prewarming. 40 adult patients (18–80 yr old) undergoing an elective living donor liver transplantation were enrolled from October 2018 to April 2019. Patients with preoperative fever (> 38.0 °C) or hypothermia (< 36.0 °C), earlier history of transplant, encephalopathy, septic condition, autonomic neuropathy, thyroid dysfunction, model for end- stage liver disease score > 30, and the risk

The sample size was designed centered on the preceding study, representing that 30-min prewarming previous to surgery decrease the intraoperative low temperature incidence by 91.3%.

IV: prewarming (yes/no). DV: intraop hypothermia incidence/duration; temp trajectory; lactate/coag; postop outcomes. Liver transplant people could be disturbed more by Factors such as hypothermia, prewarming reduce intraop hypothermia by 85% with 20 patients necessary in each group (β=0.8, α=0.05, and 10% dropout rate).

PA core temp q5 min, prespecified labs. t/Mann– Whitney, χ²/Fisher, RM-ANOVA. a priori α=0.05.

In the preop room, core temperature was identified via the tympanic membrane by means of an infrared thermometer (Thermoscan 5, Braun, Kronberg, Germany) before and after the surgery. In the OR, the temp was identified once via the tympanic membrane with an infrared thermometer (Thermoscan 5 IRT 4520, Braun, Kronberg, Germany) beforehand the induction of anesthesia. Afterward the PAC, the temp was uninterruptedly deliberate in the pulmonary artery and repeatedly noted Q 5 min into the electric record of anesthesia. The PAC was

Hypothermia any drop : 60% vs 95% (P=0.020); after induction: 20% vs 85% (P<0.001); duration: 60 vs 383 min (P=0.002); temp nadir less (P=0.040); slope slower (P=0.007); lactate change greater (P=0.034); other NS. Clinical influence of intraop hypothermia and the profits of normothermia are well settled in numerous surgical locations, they have not been well established in liver transplantation. The findings enhance a significant indication on scientific advantages of intraop normothermia during liver transplant.

In conclusion, forced-air prewarming reduce the occurrence and length of intraop hypothermia with possible advantage while temporary avoiding the core-to- peripheral heat redistribution.

Level I RCT; high internal validity; single center/small N; Worth to practice.

of malignant hyperthermia were excluded from the study. This prospective, parallel-group, assessor-blind randomized controlled trial was accepted by the Samsung Medical Center Institutional Review Board on 6/4/2018 (SMC 2018-05-061- 005) and listed at the Clinical Research Information Service on 8/1/2018. Informed consent was gotten from the members and all approaches remained completed in agreement with the pertinent rules.

disconnected proximately before moving the pt to ICU based on the policy of the center.

2. Becerra Á, et al.

Double-blind, randomized controlled trial in patients undergoing

Sample size study in 56 patients receiving spinal anesthesia, in which

IV: Duration of prewarming (0/15/30/45 min). DVs: Rectal temperature over

Tympanic thermometer preop (average of 3 readings); esophageal

Recurrent measures multivariate examination of covariance demonstrated by

Pre-induction temperature after prewarming was +0.3 °C (15 min vs control, 95% CI

This RCT on surgeries ongoing < 60 min under GA shows that active

Level I (RCT), strong internal validity, double- blind design, large N, dose–

bladder or prostatic transurethral resection under anesthesia.

hypothermia established in 96% of non- prewarmed people. Power analysis was performed to detect a temp change of 0.15 °C (± 0.05 °C) at the end of the procedure. To notice changes in the esophageal temp, 40 pts in each group were appraised to offer 80% power at an alpha level of 0.05. Surgery lasted < 60 min and numerous temp amounts were documented intraop at 15, 30, & 45 min. Since in some pts the surgery took < 30 min, temp at 30 or 45 min might not be measured. Under the anticipation of absent information at 30 or 45 min in many pts, the sample size was augmented to 293 pts.

time (primary), hypothermia at end of surgery (<36.0 °C), shivering at arrival to PACU (observer-visible), pain at 30 min in PACU (NRS), Length of stay in PACU, and postoperative complications (cardiac events, bleeding, transfusion).

thermometer intraop; temperatures every 15 min; NRS pain (ordinal); PACU LOS (min). No fluids/irrigation warmed; OR temp also recorded. No reliability coefficients reported (expected: trained staff; standardized devices). Categorical χ²; means t-test; non- normal Kruskal– Wallis; periop temperatures analyzed with repeated-measures MANCOVA (with Dunnett contrasts compared to control group) adjusting for baseline; one-way ANOVA for PACU LOS; Kaplan–Meier + log-rank for LOS; α=0.05; R 3.3.1.

the temp response at each reflection time rendering to prewarming. The models were inspected between temp variables in subjects permitting to prophylaxis. 297 patients were enrolled and casually appointed 76 pts to control group, 74 pts to 15- min group, 73 pts to 30-min group, and 74 pts to the 45-min group. Temp in the control group earlier than induction was 36.5 ± 0.5 °C. Behind prewarming, core temp was meaningfully superior in 15- and 30-min groups (36.8 ± 0.5 °C, p =0.004; 36.7 ± 0.5 °C, p=0.041, respectively). Body temp at the finish of surgery was considerably inferior in the control group (35.8 ± 0.6 °C) than in the 3 prewarmed groups (36.3 ± 0.6 °C in 15-min, 36.3

0.1 to 0.4, p=0.004); +0.2 °C (30 min, 0.0 to 0.3, p=0.041) and NS (p=0.203) (45 min). The end-of- surgery temp was higher in the prewarming groups than in the control group (mean±SD): 35.8±0.6 °C for control vs 36.3±0.6/0.5/0.6 °C (15/30/45 min), all p<0.001. MANCOVA analysis revealed the overall effects of prewarming (p<0.001) and of time×treatment (p<0.001) to be significant. The overall temperature was increased by a mean of 0.4 °C with both 30 min and 45 min prewarming vs control (p=0.010 and p=0.003, respectively) but not with 15 min (p=0.099) during surgery. Hypothermia at the end of surgery was less common with prewarming: 54%

prewarming for at least 15 min decreases redistribution hypothermia, the reduction of body temp through periop time, and the occurrence of hypothermia at the end of the time of surgery. Clinical relevant findings is that prewarming time-periods also decrease postop shivering, postop pain, and interval of stay in PACU.

response (time) arms, appropriate longitudinal stats. Single center; short urologic GA with LMA (generalizability) ; esophageal temp; irrigating fluids not warmed; male- predominant cohort. Worth to practice use forced-air prewarming (aim 30 min when feasible; ≥15 min still beneficial).

± 0.5 °C in 30-min, and 36.3 ± 0.6 °C in 45-min group) (p <0.001). Prewarming previous to short- term transurethral resection under GA decrease the body temp drop during the periop time. Also reducing the degree of postop complications.

(control) vs 23%/25%/30% (15/30/45 min), p<0.001. The PACU incidence of shivering was lower in the prewarming groups than in the control group: 42% in the control vs 0% (30 min) and 4% (15 and 45 min), with OR 0.058 (95% CI 0.017 to 0.201). Pain (NRS 30 min) was lower in all prewarming groups than in the control (between-group diff ≈ 1.0 to 1.2, all p<0.001). PACU LOS was shorter after prewarming by 34/42/38 min (15/30/45 min) vs control; p=0.001.

3. Shim J- W, et al.

A total of 68 pts for elective PNL were enrolled for this report from January-June 2022, but 2 pts were excluded since there was a change in the plan of the surgery. Once randomization

We calculated the sample size using a two-sided Fisher’s exact test at a significance level of p < 0.05. With a 5% risk of type 1 error and a 20% risk of type 2 error, 30 patients were

The demographic findings included sex, age, body mass index, ASA classification I and II, and comorbidities (i.e., hypertension, diabetes mellitus, hepatitis B, and tuberculosis). The surgical findings

Tympanic infrared temps (preop and in PACU), esophageal core temp (intraop), timepoints T0–T9, shivering by clinical definition, operating room (OR) 23 °C, room-temperature IV fluids and irrigation, continuous variables

Serial changes in perioperative core body temp were evaluated using the Friedman test, with post hoc analysis performed using the Wilcoxon signed– rank test. All statistical tests were two-sided, and a

The main finding of this study was that 10 min of preoperative warming using a forced- air warming device was effective in reducing early hypothermia during PNL. In addition,

Prewarming for 10 min decreased early hypothermia, preserved intraoperative body temperature, and improved postoperative recovery in the PACU.

Level I (RCT); proper randomization and statistics; blinding of the assessor; clinically relevant endpoints. Limitations: single center study; small

was done, pts in the prewarming group (n = 32) got warm using a forced-air warming machine for 10 min in preop before transfer to the OR, while the controls (n = 34) did not. The hypothermia incidence inside the 1st hr after general anesthesia was induced was the primary outcome. Periop body temp and postop retrieval results were also assessed.

required in each group. We enrolled 68 patients, considering a dropout rate of 10%.

included operation site (right, left, or both sides), total case length, patient positioning time, and administered volumes of irrigation and intravenous fluids. Duration of recovery in the PACU, hospital stay, and Clavien– Dindo classification were also recorded.

(temperature) = continuous, outcomes such as hypothermia/shiveri ng = nominal, no reliability coefficients reported.Normality assessed by Shapiro–Wilk, χ 2 /Fisher’s exact tests (categorical variables), t-test or Mann–Whitney (continuous variables between groups), Friedman’s test for serial temperature measurements (Wilcoxon signed- rank test for post hoc analysis), two- sided α=0.05, SPSS version 24.

p-value < 0.05 was considered significant. All analyses were performed with SPSS Statistics software (version 24.0; IBM Corp., Armonk, NY, USA).

the prewarmed patients experienced less of a decrease in their core body temperature during surgery, compared to the controls. Prewarming also significantly decreased the incidence of shivering and recovery duration in the PACU. These findings demonstrate that prewarming practices, including the use of forced- air warming, can be beneficial in maintaining intraoperative body temperature during complex and lengthy surgeries like liver transplantation

sample; patients were not blinded; PNL setting (prone position, irrigation) may limit external validity. Worth to practice: Yes– implement ≥10 minutes prewarming if 30 minutes is not possible.

4.Cho J, et al.

This study was accepted by the Institutional Review Board of Sanggye Paik Hospital (approval no. 2021-05-004). It

Sample size was obtained by approximating a core temp variance of up to 0.5°C as the wanted therapeutic effect

Prewarming (10 min with a forced- air blanket) + warmed IV fluid versus no prewarming + room-temp IV fluid.

Tympanic (baseline, pre-op, PACU, awake) and esophageal probe (intra-op). Thermal comfort: 10-point scale (0 = cold, 5 = neutral, 10 = hot).

Intraoperative hypothermia: 64% of control group vs. 29% of prewarming group (p = 0.015). Average magnitude of temp decreases were found of 0.93

Brief prewarming for 10 min plus warmed IV fluid considerably decrease intraop hypothermia and augmented patient-

A feasible and simple intervention, a brief period (10 minutes) of prewarming combined with warmed IV fluids is effective at

Randomized design, clinically important intervention, validated measurements, results easy to apply. Small

is a prospective, randomized, single-blinded, controlled study intended in agreement with Consolidated Standards of Reporting Trials guidelines for randomized clinical trials. Composed informed agreement was gotten from all members. This study was listed at clinicaltrials.gov earlier to patient registration (registration no. NCT04991272).

since this is the change connected to hypothermia- induced complications. The sample size for every group was 23 (ɑ = 0.05, ß = 0.9) using G Power version 3.1.9.4 (Franz Faul, Universitat Kiel, Germany). Presumptuous a dropout rate of 5%, 50 members were necessary.

Intraoperative hypothermia (incidence of core temperature <36.0°C). Change in core body temperature (difference of T0– Tend). Patient- reported thermal comfort. Incidence of postoperative shivering.

Student’s t-test, Chi- square, Mann- Whitney U, Fisher’s exact test, linear mixed model (SPSS v22, SAS v9.4). p- value < 0.05.

± 0.3°C in control VS 0.55 ± 0.4°C prewarming, p = 0.0001. The rate of temp decrease was 0.012 ± 0.004°C/min vs. 0.008 ± 0.004°C/min, p = 0.001, and the thermal comfort meaningfully was higher in group prewarming (p = 0.004).

reported thermal comfort.

reducing intraoperative hypothermia in patients undergoing TURB/TURP procedures. Even short operations may benefit from this strategy

sample size, single-center study, uneven group demographics (weight, ASA class), brief prewarming was interrupted during patient transport to operating room. High—brief period prewarming is feasible and easy to apply even in busy clinical practice. Level II (Randomized Controlled Trial). Simple intervention reduces hypothermia and improves thermal comfort with no apparent risks.

5. Yi N, et al.

Prospective, randomized, single-blinded controlled trial. Composite warming (forced- air warming + water blanket + preheated OR + postoperative rewarming) vs.

N = 74 patients (37 composite warming, 37 forced-air warming). Adult patients (18–75 years) scheduled for elective open hepatectomy for

Composite warming strategy compared to forced-air warming only. Incidence of intraoperative hypothermia (core temperature <36°C). Intraoperative

Nasopharyngeal probe intraop was measure and recorded Q 5 min, temp data analyzed every 30 min); tympanic thermometer in PACU. Numeric Rating Scale (NRS) and Visual Analog

Intraoperative hypothermia (perioperative core temperature <36 °C): 21.6% in the composite group vs. 48.6% in the forced-air group, p = .015. Mean anesthesia time was

Composite warming with multiple modalities compared to simple prewarming with forced-air (controls) significantly reduced the incidence of intraoperative

Composite warming with a multimodal approach is superior to simple prewarming with forced-air in patients undergoing open hepatectomy. Blood loss ≥245 mL, fluid volume

Worth to Practice/Level. Randomized design, clear warming protocols for both groups, robust statistical analysis. Intervention likely benefits

forced-air warming alone.

hepatocellular carcinoma. Single-center: First People’s Hospital of Neijiang, China.

temperature changes. Intraop blood loss, fluid replacement, duration of anesthesia. PACU stay time.

Scale (VAS). The blood loss was measured with a pre-heparinized suction system, with precise volume of fluid subtracted. Independent t-test (for normally distributed continuous data), ANOVA, Chi- square/Fisher’s exact tests (categorical data), ROC curves and multivariate logistic regression (SPSS v26 software). P < .05 = statistically significant.

significantly shorter with composite warming (228 vs. 250 minutes, p = .002).Significantly lower intraoperative blood loss with composite warming (192 vs. 260 mL, p < .001).Fluid volume (replacement fluids) was significantly lower with composite warming (913 vs. 1473 mL, p = .035).PACU observation time was significantly lower with composite warming (20 vs. 29 minutes, p = .017).Numeric and visual pain scores were not significantly different between groups.Hospital stay was not significantly different between groups.Minor (mostly Grade I–II) complications occurred in several patients but was not significantly different in severity

hypothermia, intraoperative blood loss, the amount of fluid replacement required, and PACU observation time. The differences were most pronounced in surgical times >3 hours.

≥1535 mL, and anesthesia duration ≥265 min were independently associated with increased risk of hypothermia.

high-risk surgical group. Single- center, small sample size, anesthetic drugs not matched between groups, only liver cancer patients, reducing generalizability to other groups.Moderate – composite intervention requires several modalities (forced-air + water blanket + pre-heated OR) and is more resource- intensive than simple prewarming. Level I (Randomized Controlled Trial). Yes – especially in the setting of long abdominal procedures with increased risk of perioperative hypothermia.

between the two groups.

6. Okgün Alcan A, et al.

Compare the efficiency of forced-air warming system with resistive warming mattress in reducing the incidence of intraoperative inadvertent hypothermia (IIH). Compare these active methods with their combination. Prospective, parallel-group, randomized controlled trial (3 arms). .

N = 123, 41 patients per group. Age: Adults 18–64 years. ASA classification: I– III.Operating rooms in a training & research hospital in Izmir, Turkey.Elective orthopedic procedures >30 min, performed under spinal anesthesia.

Independent variable (predictor, manipulated) = method of warming (3 levels). Dpendent variables (outcomes, predicted, measured) = incidence of IIH (core temp <36°C), intraoperative changes in temperature, incidence of shivering or feeling cold, cyanosis, patient satisfaction (VAS 0–10).

Temperature: Infrared tympanic thermometer (baseline, q15min during operation, and at end of surgery).Patient satisfaction: 10 cm visual analog scale. Shapiro-Wilk for normal distribution; Chi-square, Fisher’s exact, Kruskal- Wallis for between- group comparisons. p < .05 is significant.

Incidence of IIH: Group 1 = 9.8%, Group 2 = 9.8%, Group 3 = 4.9% (no sig. diff., p = .647). Mean intraop temps: 36.51°C Group 1, 36.51°C Group 2, 36.63°C Group 3. (no sig. diff. ). Group 1 = 17%, Group 2 = 18%, Group 3 = 61% (highest in Group 3, p = .002). Group 1 = 60.8%, Group 2 = 63.6%, Group 3 = 73.2% (highest in Group 3, p = .008). Group 1 = VAS 7.69 ± 1.1, Group 2 = VAS 8.08 ± 0.91, Group 3 = VAS 8.65 ± 0.89 (highest in Group 3, p = .005).

All effective strategies to maintain normothermia involved active warming. No combination strategy was more effective than the use of a single method in reducing the incidence of IIH.Patients in the combination group experienced more shivering and cold sensation; however, they reported greater overall satisfaction.

Resistive and forced-air modalities are both effective when used alone. Dual modality use did not offer significant benefit over single modalities for the prevention of hypothermia but is associated with higher patient satisfaction at the expense of increased shivering/cold sensation.

Level II, RCT, sample size, stratified randomization, and choice of outcome measures. Findings are not generalizable beyond young adult orthopedic surgical population, relatively short/moderate duration surgeries (longer surgeries might benefit more from any active warming methods), and spinal anesthesia (in combined spinal epidural technique. The outcome might have been different in a more severe surgical trauma such as open surgery. Intravenous fluids were not recorded.Easy,

both methods are already in clinical use. Combination of methods increases total cost, nursing workload, and waste products. Worth to practice but no need to combine methods; either one is enough to maintain normothermia.

7. Desai R, et al.

Prospective, randomized, non-blinded clinical trial. Patients randomized to 4 arms with different pre- and intraoperative warming combinations: Conductive warming (CW)/CW, Forced-air warming (FAW)/FAW, No prewarming (NAPW)/CW, No prewarming (NAPW)/FAW.

N = 182 adult patients undergoing planned surgery under general anesthesia of intermediate duration (90–240 min).Single tertiary academic hospital: Cooper University Hospital, Camden, NJ, USA. Population: Broad surgical mix: abdominal, gynecologic, breast, reconstructive, urologic procedures.

IV: Warming strategy: CW vs FAW; with or without prewarming. DV: Primary: Area under the curve (AUC) of intraoperative core temperature <36°C.Secondary: Incidence of hypothermia, relative hypothermia (AUC/case duration), LOS, blood loss, transfusion, comfort (Likert 0– 10).

Core temperature measured with esophageal probe (recorded every 15 min). Measured on Likert scale 0–10. Mixed-model analysis (adjusted for 10 surgical blocks) as primary analysis of AUC, Kruskal-Wallis for nonparametrics, Chi-square/Fisher’s for categorical analyses. Statistical analysis with SAS 9.4 & R 4.2.2. Two- tailed p-values, significant at p < .05.

Findings (include 2–3 major results with brief supporting explanation) Area under the curve (AUC) of intraoperative core temperature below 36°C: AUC <36°C (median) for CW/CW = 4.7; FAW/FAW = 8.0; NAPW/CW = 7.4; NAPW/FAW = 19.9. CW/CW and NAPW/CW groups had AUC <36°C that were ~51% and ~54% less than in NAPW/FAW group. Relative AUC (AUC/case

CW (with or without prewarming) was superior to FAW when prewarming was not used. With prewarming, CW and FAW had similar performance. Prewarming significantly increased the efficacy of FAW.

CW is superior to FAW if used without prewarming. When used with prewarming, FAW is non-inferior to CW. Prewarming with FAW appears to be an essential component in order to achieve its maximum efficacy.

This RCT supports perioperative warming with either CW or FAW + prewarming. Worth to Practice Large RCT with multi- specialty population and rigorous statistical model. Study examined clinically relevant and important outcomes. Study underpowered for prespecified sample size (intended to

duration) was significantly lower for FAW/FAW and NAPW/CW vs NAPW/FAW (48% less hypothermia, p ≈ 0.04). No significant differences were found between arms for secondary outcomes (LOS, blood loss, transfusion, complications).

enroll 216 but recruited only 182) and may have been underpowered for the planned per protocol analysis. Largely female sample (80%). Arms using conductive warming were not balanced with arms using forced air warming (i.e., no CW/FAW crossover arms). In the NAPW arms, the use of warming blankets was not standardized.Usi ng either FAW and CW devices is high: both are available on most hospital wards and ORs. Use of prewarming is likely highly feasible and practical.

8. Yoo JH,et al.

Prospective, randomized, partially blinded controlled trial.

N = 120 patients randomized; 116 analyzed (58 per group).Adults

Blanket position (upper vs. lower body). Primary: Incidence of intraoperative

Core temperature: Nasopharyngeal probe intraop (measurements every 15 min);

Intraoperative hypothermia: 55.2% (upper) vs. 75.9% (lower), OR 0.392 (95% CI:

Upper-body warming was more effective than lower-body warming in

In adult patients undergoing spine surgery in the prone position, upper-body blanket

Level II, RCT design with robust methodology and statistical

≥19 years, ASA I–III. Excluded: BMI >35, preop temp >38°C or <36°C, pregnant.Depart ment of Anesthesiology, Soonchunhyang University Hospital, Seoul, South Korea (2019).

and postoperative hypothermia (temperature <36.0 °C). Secondary: Changes in perioperative temperatures; duration/severity of hypothermia, incidence of PACU shivering, thermal comfort (VAS 0– 100), satisfaction (Likert 0–4), PACU LOS.

tympanic preop and PACU.Thermal comfort: 100 mm visual analog scale. Shivering: 4-point scale (0–3). Patient satisfaction: Likert 0–4. Intention-to- treat. t-test/Mann– Whitney, Chi- square/Fisher’s exact, mixed-effects model, Bonferroni post-hoc, multivariable logistic regression (risk factors).

0.177–0.866), p = 0.019.Postoperative hypothermia: 21.4% (upper) vs. 49.1% (lower), OR 0.282 (95% CI: 0.124–0.643), p = 0.002.Severity: Lower group experienced more moderate–severe hypothermia than the upper group.Duration of intraoperative hypothermia: Upper warming was associated with a shorter duration of intraoperative hypothermia (20 vs. 102 min, p = 0.005).Blood loss, transfusion, shivering, thermal comfort, satisfaction, PACU LOS: no significant differences between groups. Independent risk factors for intraoperative hypothermia: ASA II–III, anesthetic duration ≥225 min, and BSA/weight ratio ≥0.025 m2/kg. Independent protective factors:

reducing the incidence of intra- and postoperative hypothermia during prone spine surgery. Thermal comfort and satisfaction outcomes were not different between groups.

warming was superior to lower- body warming in the prevention of intra- and postoperative hypothermia. The risk of intraoperative hypothermia increases with increasing ASA classification, long duration of anesthesia, and a high BSA-to- weight ratio.

analysis, including mixed- effects and regression modeling, clinically relevant primary and secondary outcomes.Single- center study with modest sample size, enrolled only thoracolumbar spine surgery patients, no long- term outcomes or follow- up.High— blankets are widely available and inexpensive, easily applied to patients.Worth to Practice, clinically meaningful benefit demonstrated for spine surgery patients positioned in the prone position.

upper body warming, OR temp ≥20.0 °C, and preop temp ≥36.5 °C.

9. Gulia A, et al.

Prospective randomized controlled trial. Randomized assignment of patients to underbody vs. over-body forced air warming blanket during laparoscopic colorectal surgery

60 adult patients (ASA I–II, 18–65 yr old).All elective laparoscopic colon surgeries.Single tertiary care center (AIIMS, New Delhi, India). Randomized 30 per group.Excluded uncontrolled HTN, CAD, morbid obesity, preop temp >37.5°C, surgeries <2 hr

IV: Type of forced air warming blanket (underbody vs. over-body). DV: Core temperature (°C) intraoperatively. Postoperative shivering (yes/no). Time to reach Aldrete score of 10 in PACU. Hemodynamics (HR, MBP, EtCO2). . . .

Core temperature: nasopharyngeal probe. Hemodynamics: ECG, MBP, HR, EtCO₂ monitored intraoperatively. Aldrete score used for PACU recovery. Linear mixed model (temperature trends). Unpaired Student t- test (continuous variables). Fisher’s exact test/Chi- square test (categorical variables). Significance threshold p<0.05 (p<0.012 for repeated measures)

Core temp higher in underbody group at 60, 90, 120, 150 min (all p<0.01).Aldrete score 10 achieved faster in underbody group (14.3±2.5 vs. 16.8±3.6 min, p=0.003).Shivering: 1 case (underbody) vs. 4 cases (over- body). No significant differences in MBP, HR, EtCO₂, fluids, urine output

Both warming systems effectively prevented significant hypothermia. Underbody blanket provided slightly higher intraoperative temperatures and faster PACU recovery, but clinical differences were minimal. Incidence of shivering was lower with underbody blanket.

Underbody and over-body forced air warming blankets are comparably effective in preventing intraoperative hypothermia in laparoscopic colorectal surgeries.No clinically meaningful superiority of one system over the other

Level II (well- designed RCT with some limitations). RCT design, homogenous population, standardized anesthesia protocol, prospective registration.Singl e-center, small sample size (n=60), limited generalizability, only laparoscopic colon surgery studied.Minimal; no adverse skin or systemic complications reported.High— forced air warming already widely available in perioperative practice.Supports continued use of forced air warming systems, either underbody or

over-body, with underbody showing minor advantages.

10. Yin W, et al.

Prospective, single-center, randomized, controlled trial; CONSORT; two arms; same FAW blanket under body but at different sides of the patient (under vs. over) during arthroscopic shoulder surgery (lateral decubitus position).

N=100 enrolled; 96 analyzed (UB=47, OB=49) Adults, American Society of Anesthesiologists (ASA) I–II, 18– 70 years old, estimated duration of surgery >80 min. Exclusions: BMI>30, thyroid dysfunction, severe vascular disease, contraindication to nerve block, or patient refusal. Setting: Sichuan Provincial Orthopedic Hospital, People’s Republic of China (January 14 to October 30, 2021; trial registration: ChiCTR2100042 071).

IV: Placement of the FAW blanket (underbody blanket under the patient vs. over the patient). DV:Intraoperative near-core temperature; postoperative hypothermia, defined as temperature <36 °C; and postoperative shivering (yes/no).

Continuous core temperature with the iThermonitor WT705 wireless axillary sensor (validated for estimating core temperature); intermittent: baseline (Ta), prior to induction of GA (Tb), prewarming (T0), then every 15 min to 90 min. Data examined with independent t-tests for constant results, χ²/Fisher’s exact for categorical; 2-tailed α=0.05; calculated sample size with 80% power to detect an estimated 0.6 °C difference in temperatures assuming standard deviation 0.6

At 45 min post T0 until the end of surgery, all OB > UB (p<0.05 for all: T45 p=0.01; T60 p=0.003; T75 p<0.001; T90 p<0.001). At 90 min: OB 36.1 ± 0.4 °C vs. UB 35.8 ± 0.4 °C, p<0.001 (OB higher). Postoperative temperature 36.2 ± 0.4 °C (OB) vs. 35.9 ± 0.4 °C (UB), p<0.001 (OB higher).Postoperati ve hypothermia 32.7% (OB) vs. 57.4% (UB), p=0.023 (OB lower).Postoperativ e shivering 8.2% (OB) vs. 19.1% (UB), p=0.143 (NS for difference).

Placing the underbody blanket over patients achieved modestly higher intraoperative temperatures and significantly reduced postoperative hypothermia, but with small absolute temperature differences that did not exceed the prespecified threshold of clinical relevance (0.6 °C). Fewer patients were hypothermic postoperatively in the OB group— clinically meaningful for the prevention of inadvertent perioperative hypothermia (IPH) in shoulder arthroscopy with room-temperature irrigation.

Using a full-access underbody FAW blanket, we recommend that the blanket be placed over patients for arthroscopic shoulder surgery to more effectively prevent inadvertent perioperative hypothermia. Both blanket positions provided active warming but OB positioning yielded superior temperature profiles and a lower rate of hypothermia.

Level II, RCT design; adequately large analyzed sample (n=96); standardized anesthetic and surgical techniques and perioperative management; continuous temperature monitoring with a validated device; prespecified threshold for clinical relevance. Single-center study; single surgery and body position (arthroscopic shoulder surgery, lateral decubitus position); irrigation not warmed; no comparison with the standard upper-body OB blanket. Minimal (routine and safe

FAW technique). High (only implementation required is choice of blanket placement). Worth to Practice the OB placement of the underbody FAW blanket is preferred for shoulder arthroscopy to lower postoperative hypothermia.