Intraoperative core temperature and infectious complications after colorectal surgery: A registry analysis

Inadvertent perioperative hypothermia and surgical site infections after liver resection

BACKGROUND

In the overall surgical population, inadvertent perioperative hypothermia has been associated with an increased incidence of surgical site infection (SSI). However, recent clinical trials did not validate this notion. This study aimed to investigate the potential correlation between inadvertent perioperative hypothermia and SSIs following liver resection.

METHODS

This retrospective cohort study included all consecutive patients who underwent liver resection between January 2019 and December 2021 at the First Affiliated Hospital, Zhejiang University School of Medicine. Perioperative temperature managements were implemented for all patients included in the analysis. Estimated propensity score matching (PSM) was performed to reduce the baseline imbalances between the normothermia and hypothermia groups. Before and after PSM, univariate analyses were performed to evaluate the correlation between hypothermia and SSI. Multivariate regression analysis was performed to determine whether hypothermia was an independent risk factor for postoperative transfusion and major complications. Subgroup analyses were performed for diabetes mellitus, age > 65 years, and major liver resection.

RESULTS

Among 4000 patients, 2206 had hypothermia (55.2%), of which 150 developed SSI (6.8%). PSM yielded 1434 individuals in each group. After PSM, the hypothermia and normothermia groups demonstrated similar incidence rates of SSI (6.3% vs. 7.0%, P = 0.453), postoperative transfusion (13.3% vs. 13.7%, P = 0.743), and major complications (9.0% vs. 10.1%, P = 0.309). Univariate regression analysis revealed no significant effects of hypothermia on the incidence of SSI in the group with the highest hypothermia exposure [odds ratio (OR) = 1.25, 95% confidence interval (CI): 0.84-1.87, P = 0.266], the group with moderate exposure (OR = 1.00, 95% CI: 0.65-1.53, P = 0.999), or the group with the lowest exposure (OR = 1.11, 95% CI: 0.73-1.65, P = 0.628). The subgroup analysis revealed similar results. Regarding liver function, patients in the hypothermia group demonstrated lower γ-glutamyl transpeptidase (37 vs. 43 U/L, P = 0.001) and alkaline phosphatase (69 vs. 72 U/L, P = 0.016). However, patients in the hypothermia group exhibited prolonged activated partial thromboplastin time (29.2 vs. 28.6 s, P < 0.01).

CONCLUSIONS

In our study of patients undergoing liver resection, we found no significant association between mild perioperative hypothermia and SSI. It might be due to the perioperative temperature managements, especially active warming measures, which limited the impact of perioperative hypothermia on the occurrence of SSI.

Modified intraoperative temperature management prevents prolonged length of stay after head and neck surgery with free flap reconstruction

The present study aimed to investigate the association between intraoperative body temperature and prolonged length of stay (PLOS) after free flap reconstruction. A total of 753 patients who underwent head and neck surgery with free flap reconstruction were collected and randomly assigned into primary and validation cohorts. In the primary cohort, univariable and multivariable analyses were conducted to evaluate associations between intraoperative time-weighted (TW) temperature (TW average [TWA] temperature, TW hypothermia and TW hyperthermia) and PLOS. Nomograms were developed with and without intraoperative TW temperature, and validated in the validation cohort. Severe intraoperative TW hypothermia (OR = 1.004; 95% CI: 1.000, 1.007; p = 0.032) was identified as an independent risk factor for PLOS. Intraoperative TWA temperature and TW hypothermia showed linear related predictive effect for PLOS. The nomogram incorporating intraoperative TW temperature showed higher C-index (0.652, 95% CI: 0.591, 0.713) and improved net reclassification improvement for non-event (0.277, 95% CI: 0.118, 0.435; p < 0.001). Lower TWA temperature with mild TW hypothermia had a preventive effect on PLOS with a linear association, which may provide a modified range for intraoperative temperature management. The proposed nomogram incorporating intraoperative TW temperature could be used to develop personalized preventive strategies for PLOS after free flap reconstruction. IRB NUMBER: SYSEC-KY-KS-2022-037. CLINICAL TRIAL REGISTRATION NUMBER: Not applicable.

[Correlation Between 6 Characteristics of Perioperative Hypothermia and Allogeneic Red Blood Cell Transfusion in Abdominal Surgery Patients]

Objective

To explore the correlation between six characteristics of perioperative hypothermia and allogeneic red blood cell (RBC) transfusions in patients who underwent abdominal surgeries.

Methods

Patients who underwent abdominal surgeries at West China Hospital, Sichuan University between October 2019 and July 2021 were retrospectively enrolled. A wearable wireless temperature sensor was used to continuously monitor the core body temperature of patients throughout the perioperative period. The perioperative temperature nadir, maximum temperature loss, percentage of time with hypothermia, time-weighted average temperature, area under the curve (AUC) at 36 ℃, and AUC at 37 ℃ were calculated for the period from entering the operation room to 24 hours after the end of anesthesia. The restricted cubic spline (RCS) and multiple logistic regression models were used to explore the correlation between these temperature characteristics and perioperative allogeneic RBC transfusions.

Results

A total of 3119 patients were included in the study, with an allogeneic RBC transfusion rate of 2.8%. The RCS model showed that allogeneic RBC transfusion was associated with the perioperative temperature nadir (Poverall=0.048) and AUC at 36 ℃ (Poverall=0.026) and no statistical significance was found in the nonlinear test. The association between allogeneic RBC transfusions and other temperature characteristics was not statistically significant. According to the RCS model results, cut-off points were taken to form groups based on the body temperature characteristics. Multivariate logistic regression showed that the perioperative temperature nadir<35.5 ℃ (odds ratio [OR]=2.47, 95% confidence interval [CI]: 1.21-5.03) and AUC at 36 ℃≥100 ℃·min (OR=2.24, 95% CI:1.09-4.58) were associated with increased demand for allogeneic RBC transfusion.

Conclusion

Hypothermia is associated with an increased need for perioperative allogeneic RBC transfusions and has a cumulative effect over time. For patients at high risk of bleeding, attention should be paid to the prevention of perioperative hypothermia and reduction in the cumulative exposure to hypothermia, thereby reducing the need for blood transfusion.

Impact of Intraoperative Hypothermia on Autologous Breast Reconstruction

OBJECTIVE

Studies have identified perioperative hypothermia as a risk factor for impaired wound healing, increased hospital length of stay, and surgical site infection. This study examines the effect of intraoperative hypothermia on postoperative outcomes in autologous microvascular free flap breast reconstruction.

METHODS

This was a retrospective review of 55 patients who experienced intraoperative hypothermia, defined as less than 35.0°C core body temperature and 99 normothermic patients who underwent autologous-based microvascular free flap breast reconstruction from 2013 to 2021. Demographics, comorbidities, smoking status, intraoperative warming devices, type of autologous reconstruction, hypothermia (and its duration), and length of surgery were collected. The outcomes assessed were infection rate, reoperation within 90 days, skin necrosis, wound healing complications, hematoma, seroma, and readmission within 90 days.

RESULTS

In the study population of 154 consecutive patients, 8.4% had type 1 or type 2 diabetes and 3.2% were current smokers. A total of 90.3% of patients (139) underwent deep inferior epigastric perforator flap reconstruction, 7.1% (11) superficial inferior epigastric artery flap reconstruction, and 4 (2.6%) another free flap type. A total of 35.7% of the patients (55) experienced intraoperative hypothermia defined as less than 35.0°C. In the hypothermic group, a higher proportion of patients had wound healing complications (52.7% vs 29.3%, P < 0.05), hematoma (16.4% vs 5.1%, P < 0.05), and readmission for postoperative complications (34.5% vs 14.1%, P < 0.05). There was also a trend toward higher incidence of seroma (7.3% vs 5.1%), surgical site infection (12.7% vs 9.1%), skin necrosis (12.7% vs 9.1%), and unplanned reoperation within 90 days (10.9% vs 7.1%). Further analysis via Firth logistic regression demonstrated intraoperative hypothermia predicted postoperative hematoma (odds ratio [OR], 3.68; 95% confidence interval [CI], 1.17-11.60; P < 0.05), readmission within 90 days (OR, 3.20; 95% CI, 1.45-7.08; P < 0.05), and wound healing complications (OR, 2.69; 95% CI, 1.36-5.33; P < 0.05).

CONCLUSIONS

This study demonstrates that intraoperative hypothermia is a significant risk factor for postoperative wound healing complications, hematoma, and readmission within 90 days in autologous breast reconstruction. Because of a finite amount of donor sites, it is important to find ways to minimize the risk of postoperative complications. Our results support that maintaining strict normothermia during autologous breast reconstruction can significantly improve patient outcomes and reduce morbidity.

Impact of a quality improvement intervention on the incidence of surgical site infection in patients undergoing colorectal surgery: Pre-test-post-test design

AIMS AND OBJECTIVES

The aim of this study was to measure the impact of a complex quality improvement intervention on the incidence of SSI in patients undergoing elective colorectal surgery.

BACKGROUND

Surgical site infections are a major postoperative complication for patients undergoing colorectal surgery. Prevention of SSIs necessitates a complex intervention requiring many elements to be in place to ensure the successful implementation of prevention measures.

DESIGN

This study was a non-equivalent pre-test post-test design where consecutive patients undergoing colorectal surgery were surveyed for surgical site infections for 30 days postoperatively and is reported using the SQUIRE 2.0.

METHODS

A baseline cohort of patients was retrospectively reviewed in a single centre to ascertain the surgical site infection incidence rate in the first 6 months of 2018 (T0) and prospectively at two 6-month time periods in 2019 (T1, T2) following the introduction of a complex intervention. There were 311 patients included across three time periods.

RESULTS

There was a notable decrease in surgical site infection incidence rates from baseline over the course of the study. Univariate analysis identified Body Mass Index, a wound contamination classification of dirty or contaminated, duration of surgery >75th percentile and a National Healthcare Safety Network risk index score of 3 as factors that significantly increase the probability of developing a surgical site infection. Multivariate analysis identified duration of surgery and body mass index increased the probability of an SSI. The results of the logistical regression model found that there was a significant reduction in the probability of an SSI between T0 and T2.

CONCLUSIONS

The implementation of a complex intervention led to a reduction in the incidence of surgical site infections and improved implementation of evidence-based practices as part of a care bundle in relation to the prevention of surgical site infections in patients undergoing elective colorectal surgery.

RELEVANCE TO CLINICAL PRACTICE

A multicomponent multidisciplinary complex intervention as part of a quality improvement project can successfully reduce the incidence rates of surgical site infections in patients who require elective colorectal surgery. Normalisation Process Theory provides guidance and support in implementing complex interventions for the prevention of surgical site infection.

PATIENT OR PUBLIC CONTRIBUTION

Patients provided post-discharge information on their wound healing as part of the surveillance component of the intervention. Five patients reviewed and provided feedback on a patient information booklet which was developed from this quality improvement intervention. A multidisciplinary steering group guided all stages of the project.

Safety of intraoperative hypothermia for patients: meta-analyses of randomized controlled trials and observational studies

BACKGROUND

Previous studies have shown that intraoperative hypothermia was associated with higher risks of clinical adverse events, but we found otherwise from recent evidences. This study aims to synthesize the existing evidence evaluating safety of intraoperative hypothermia.

METHODS

Articles, reviews, ongoing trials and grey literatures were retrieved from PubMed, The Cochrane Library, Clinical Trails and CNKI (a Chinese national database) till February 2nd, 2019. Both randomized controlled trials and observational studies compared incidences of all sorts of intra- and post-operative consequences between hypothermia and normothermia were included. Researches comparing different warming systems were excluded. We also examined risks of hypothermia using lowered standards (35.5 °C and 35 °C) from a Chinese trial (ChiCTR-IPR-17011099).

RESULTS

A total of 9 RCT studies and 11 observational studies were included. RCT-synthesized results showed that intraoperative hypothermia was associated with higher risks of bleeding (MD = 131.90, 95%CI: 117.42, 146.38), surgical site infection (RD = 0.14, 95%CI: 0.06, 0.21) and shivering (RD = 0.32, 95%CI: 0.06, 0.58) but with no significant differences in duration of surgery, hospital stay or mortality. Observational study-synthesized evidences showed that intraoperative hypothermia did not result in higher risks in any of these adverse events. Results didn't change even if the standard of hypothermia was lowered by 0.5-1.0 °C.

CONCLUSIONS

The study indicates that the synthesized risks resulted by intra-operative hypothermia might be overestimated and the eligibility of 36 °C to define hypothermia is not sensitive enough. Given body-temperature protection has not been popularized in China, it is still critical to normalize the hypothermia prevention at this stage.