Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomised controlled trial

doi:10.1016/S0140-6736(01)06071-8

The Lancet

Volume 358, Issue 9285, 15 September 2001, Pages 876-880

https://doi.org/10.1016/S0140-6736(01)06071-8 Get rights and content

Summary

Background

Wound infection after clean surgery is an expensive and often underestimated cause of patient morbidity, and the benefits of using prophylactic antibiotics have not been proven. Warming patients during colorectal surgery has been shown to reduce infection rates. We aimed to assess whether warming patients before short duration, clean surgery would have the same effect.

Methods

421 patients having clean (breast, varicose vein, or hernia) surgery were randomly assigned to either a non- warmed (standard) group or one of two warmed groups (local and systemic). We applied warming for at least 30 min before surgery. Patients were followed up and masked outcome assessments made at 2 and 6 weeks.

Finding

Analysis was done on an intention-to-treat basis. We identified 19 wound infections in 139 non-warmed patients (14%) but only 13 in 277 who received warming (5%; p=0·001). Wound scores were also significantly lower (p=0·007) in warmed patients. There was no significant difference in the development of haematomas or seromas after surgery but the non-warmed group were prescribed significantly more postoperative antibiotics (p=0·002)

Interpretation

Warming patients before clean surgery seems to aid the prevention of postoperative wound infection. If applied according to the manufacturers guidelines these therapies have no known side-effects and might, with the support of further studies, provide an alternative to prophylactic antibiotics in this type of surgery.

Introduction

Wound infection remains one of the most common causes of morbidity in the surgical patient despite advances in surgical practice and the widespread use of prophylactic antibiotics. The average cost of a surgical wound infection has proved difficult to estimate,¹ but hospital costs alone may be over £1500 per patient.2, 3 The costs of treatment after discharge from hospital, where most wound infections are now diagnosed,4, 5, 6 or the cost to the patient in prescription charges, loss of earnings and a reduced quality of life, are rarely taken into account.

Clean surgery is defined as uninfected, operative surgery, where no inflammation is encountered and the respiratory, alimentary, and genitourinary tracts are not opened.⁷ The importance of infection rates in clean surgery should not be underestimated as they might be seen as an indicator of quality and used to determine surgical performance.8, 9

Most studies suggest that the infection rate in clean surgery is 5% or lower.4, 10, 11, 12, 13 However, other studies have shown that if patients are followed up intensely for 6 weeks after surgery, and the definition of infection is not solely limited to the presence of a purulent discharge, then infection rates might be nearer 10%.6, 8, 14

Many factors have been shown to reduce the incidence of surgical wound infection, most of which are now part of best practice. The value of prophylactic antibiotics in clean-contaminated and contaminated surgery is not contentious but the benefits of prophylactic antibiotics in reducing wound infection rates after clean surgery remain unclear. Although it has been suggested that antibiotics are beneficial¹⁵ this idea has not been supported by other studies.14, 16

Animal and human studies have shown that intraoperative hypothermia increases the risk of wound infection.17, 18, 19 Intraoperative hypothermia is likely to cause a reduction in peripheral circulation, which may increase tissue hypoxia and make the wound more susceptible to infection, even if contamination levels are low. The process of warming using a warm air blanket, to prevent hypothermia, is becoming common practice for most major surgery but the benefits of warming during clean surgical procedures, where surgery usually lasts less than an hour.

An alternative may be to warm patients before short duration, usually day case, surgery. We aimed to assess the use of a local warming device and a warm air blanket for the reduction of infection after clean wound surgery.

Section snippets

Patients and methods

We did a randomised controlled trial to investigate the effects of preoperative warming using a local warming device and a warm air blanket on postoperative wound infection rates after clean surgery. We obtained local research ethics committee approval and informed consent from all patients. All data collection took place within the same district general hospital.

Results

From April, 1999, to May, 2000, 421 patients were recruited into the study (figure). One patient randomly assigned to local warming had his operation cancelled and four patients (two local warming and two standard) were lost to follow-up, leaving 416 patient data sets for further analysis.

139 patients received standard treatment, 138 received local warming, and 139 received systemic warming. Nine protocol violations occurred, all in the warming groups. These were mainly due to logistical

Discussion

All surgical patients are at risk of a wound infection and this risk increases if tissue perfusion is poor after surgery.²³ We have shown that a 30 min period of warming, before surgery, reduces infection rates from 14% to 5%. The length of surgery was short and core temperatures in the recovery room do not suggest that patients were hypothermic However, due to the whole surgical episode of preoperative anxiety, prolonged fasting, anaesthetic drugs, and surgery our patients are still likely to

References (27)

DJ Byrne et al.
Wound infection rates: the importance of definition and post-discharge wound surveillance
J Hosp Infect
(1994)
WilsonAPR
Surveillance of wound infections
J Hosp Infect
(1995)
PJE Cruse et al.
The epidemiology of wound infection
Surg Clin North Am
(1980)
A Bremmelgaard et al.
Computer-aided surveillance of surgical infections and identification of risk factors
J Hosp Infect
(1989)
R Gupta et al.
Antibiotic prophylaxis for post-operative wound infections in clean elective breast surgery
Eur J Surg Oncol
(2000)
T Ikeda et al.
Local radiant heating increases subcutaneous oxygen tension
Am J Surg
(1998)
W Lynch et al.
Costing wound infections in a Scottish Hospital
Pharmaco Economics
(1992)
D Zoutman et al.
Total and attributable costs of surgical wound infections at a Canadian tertiary-care centre
Infect Control Hosp Epidemiol
(1998)
KB Kirkland et al.
The impact of surgical-site infections in the 1990's: attributable mortality, excess length of hospitalization, and extra costs
Infect Control Hosp Epidemiol
(1999)
DJW Law et al.
The importance of surveillance after discharge from hospital in the diagnosis of wound infection
Ann R Coll Surg Engl
(1990)

NJ Keeling et al.

Inpatient and post-discharge wound infections in general surgery

Ann R Coll Surg Engl

(1995)

Post-operative wound infections: factors influencing the incidence of wound infections

Ann Surg

(1964)

IS Bailey et al.

Community surveillance of complications after hernia repair

BMJ

(1992)

Cited by (546)

The Effect of Prewarming on Perioperative Hypothermia: A Systematic Review and Meta-analysis of Randomized Controlled Studies
2024, Journal of Perianesthesia Nursing
One of the methods for maintaining perioperative normothermia is prewarming. This study was conducted to investigate the effect of a preoperative prewarming intervention on perioperative body temperature.
Systematic review and meta-analysis.
A literature review was conducted using PubMed, CINAHL, Cochrane Central, Science Direct, Springer Link, Scopus, Web of Science, and Ovid databases. Randomized controlled trials that investigate the effect of prewarming on body temperature in the prevention of perioperative hypothermia were included. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Methodological quality was assessed using the Cochrane Collaboration “risk of bias” tool. Meta-analysis was performed with Comprehensive Meta-Analysis, version 2. Moderator analysis and publication bias assessment were performed. Funnel plots were analyzed using Orwin's fail-safe N, Trim, and Fill test method to investigate the source of heterogeneity.
A total of 907 studies were found. The systematic review included 27 studies. Of these, 23 were included in the intraoperative meta-analysis, and 16 were included in the postoperative meta-analysis. According to the meta-analysis results, the prewarming intervention was effective in maintaining normothermia in the intraoperative (Hedge's g = 0.972, 95% confidence intervaI = 0.674 to 1.270) and postoperative (Hedge's g = 0.818, 95% confidence intervaI = 0.520 to 1.114) periods.
The findings of this systematic review and meta-analysis showed that preoperative prewarming played a significant role in providing and maintaining perioperative normothermia.
Modified intraoperative temperature management prevents prolonged length of stay after head and neck surgery with free flap reconstruction
2023, Journal of Cranio-Maxillofacial Surgery
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.
SYSEC-KY-KS-2022-037.
Not applicable.
Impact of warm saline irrigation, hyperthermic intraperitoneal chemotherapy on postoperative pain in primary ovarian cancer from the KOV-HIPEC-01 randomized trial
2023, Gynecologic Oncology
Hyperthermic intraperitoneal chemotherapy (HIPEC) has emerged as a treatment option at the time of cytoreductive surgery after neoadjuvant chemotherapy. The effect of active warming of HIPEC on postoperative pain needs to be investigated. This study aimed to investigate whether HIPEC reduces postoperative pain.
From the KOV-HIPEC-01 trial, a randomized controlled trial of HIPEC for advanced primary ovarian cancer, 184 patients with a residual tumor size <1 cm were randomly assigned to the HIPEC and control groups at a 1:1 ratio. The consumption of analgesics and pain scales were analyzed. Hyperthermic intraperitoneal chemotherapy was administered after cytoreductive surgery. The primary objective was to compare the consumption of opioids measured in morphine milligram equivalents and non-opioids measured as the maximum daily dose between the HIPEC and control groups. The secondary objective was to compare the minimum and maximum pain intensities on numeric rating scales between the two groups using a linear mixed model.
Lesser consumption of non-opioids, with a lower mean maximum daily dose on postoperative days 1 and 2, was observed. The HIPEC group also experienced lower maximum pain intensities on postoperative day 1. No overall differences in the minimum or maximum pain intensities were observed on postoperative day 7.
The addition of HIPEC to cytoreductive surgery did not lead to increased postoperative pain, as demonstrated by a reduction in the use of analgesics and lower scores on postoperative pain scales during the early postoperative period.
Influence of environmental temperature and heatwaves on surgical site infection after hip and knee arthroplasty: a nationwide study
2023, Journal of Hospital Infection
Previous studies reported higher incidence of surgical site infection (SSI) after procedures performed in summer or with high temperatures. However, no study used detailed climate data to assess this risk after hip and knee arthroplasty, and no study specifically investigated the role of heatwaves.
To assess the impact of higher environmental temperatures and heatwaves on SSI rates after hip and knee arthroplasty.
Data on hip and knee arthroplasty procedures performed between January 2013 and September 2019 in hospitals participating in the Swiss SSI surveillance were linked to climate data extracted from weather stations located in their vicinity. The association between temperature, heatwaves and SSI was studied using mixed effects logistic regression models fitted at the patient level. Poisson mixed models were fitted for both calendar year and month of the year to investigate the SSI incidence trajectory over time.
We included 116,981 procedures performed in 122 hospitals. Significantly higher SSI rates were observed for procedures performed in the summertime (incidence rate ratio 1.39, 95% CI (1.20–1.60), P<0.001; reference: autumn) or in calendar months in which the mean temperature was above 20 °C (reference 5–10 °C; odds ratio 1.59, 95% CI (1.27, 1.98), P<0.001). We observed a slight but non-significant increase in the rate of SSI during heatwaves (1.44% versus 1.01%, P=0.2).
SSI rates after hip and knee replacement appear to increase with higher environmental temperature. To establish whether, and to what extent, heatwaves increase the risk of SSI, studies involving geographical areas with larger variability in temperature are needed.
Surgical site infections
2023, Surgery (United Kingdom)
Surgical site infections (SSIs) are infections at the site of surgery within 30 or 90 days of the operation, depending on the procedure. They are a significant complication of both elective and emergency surgery and are the second highest cause of hospital-acquired infections. They have a huge cost to the NHS and lead to increased morbidity and mortality. Significant research has been done to find the causes and help create solutions, culminating in international guidelines published by the World Health Organization (WHO) in 2016. This article will discuss the different types of SSIs, the common causes and infective organisms and what the WHO have suggested we can do to prevent them.
The effects of prolonged intraoperative hypothermia on patient outcomes in immediate implant-based breast reconstruction
2023, Journal of Plastic, Reconstructive and Aesthetic Surgery
The importance of thermoregulation in surgical procedures has become a recent focus for anesthesiologists and surgeons to improve patient outcomes. In breast surgery, maintenance of normothermia has been shown to reduce surgical-site infections. However, there is a paucity of information evaluating the relationship between intraoperative core body temperatures and reconstructive surgical outcomes.
A retrospective review of patients who underwent immediate breast reconstruction following mastectomy from 2015 to 2020 was performed. Patients were classified into a majority normothermic (NT) group if patients spent greater than half of the operative time ≥36 °C or a majority hypothermic (HT) group if patients spent greater than or equal to half of the operative time <36 °C. Patient demographics, comorbidities, surgical techniques, and postoperative complications were recorded. Complications were classified according to the Clavien–Dindo Classification. Univariate and multivariate statistics were used to assess significant relationships.
A total of 329 patients met inclusion criteria, of which 174 were in the NT group and 155 were in the HT group, yielding 302 and 264 total breasts, respectively. There was no significant difference in rates of infection (p = 1.0), seroma (p = 0.27), hematoma (p = 0.61), or wound dehiscence (p = 1.0). However, patients in the HT group had significantly more overall ischemic complications (p = 0.009) and, specifically, grade IIIb ischemic complications (p = 0.04). After controlling for tobacco use, body mass index, mastectomy pattern, radiation, operating surgeon, and mastectomy weight, multivariate analysis showed increased ischemic complications in the HT group (p = 0.04).
Prolonged intraoperative hypothermia can increase the risk for the development of ischemic wounds such as tissue necrosis or eschar formation that require operative intervention. This presents reconstructive complications that increase both patient and health system burdens that could be addressed through the maintenance of normothermia. Further studies using real-time flap temperature would provide more accurate insight into the relationship between temperature and implant-based breast reconstruction.

View all citing articles on Scopus

View full text

ArticlesEffects of preoperative warming on the incidence of wound infection after clean surgery: a randomised controlled trial

Summary

Background

Methods

Finding

Interpretation

Introduction

Section snippets

Patients and methods

Results

Discussion

J Hosp Infect

J Hosp Infect

Surg Clin North Am

J Hosp Infect

Eur J Surg Oncol

Am J Surg

Costing wound infections in a Scottish Hospital

Pharmaco Economics

Total and attributable costs of surgical wound infections at a Canadian tertiary-care centre

Infect Control Hosp Epidemiol

The impact of surgical-site infections in the 1990's: attributable mortality, excess length of hospitalization, and extra costs

Infect Control Hosp Epidemiol

The importance of surveillance after discharge from hospital in the diagnosis of wound infection

Ann R Coll Surg Engl

Inpatient and post-discharge wound infections in general surgery

Ann R Coll Surg Engl

Post-operative wound infections: factors influencing the incidence of wound infections

Ann Surg

Community surveillance of complications after hernia repair

BMJ

Articles
Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomised controlled trial