Efficacy of Preoperative Warming with Wireless Temperature Monitoring in Laparoscopic Colorectal Cancer Resection: A Randomized Controlled Trial

Technical Summary: Efficacy of Preoperative Warming with Wireless Temperature Monitoring in Laparoscopic Colorectal Cancer Resection

Problem Statement
Perioperative hypothermia (IPH), defined as a core body temperature below 36°C, is a prevalent surgical complication with incidence rates ranging from 50% to 90%, particularly in laparoscopic procedures where pneumoperitoneum and anesthesia contribute to heat loss. IPH is associated with significant adverse outcomes, including surgical site infections (SSI), coagulation dysfunction, delayed anesthetic metabolism, increased shivering, and prolonged recovery times. While guidelines recommend dynamic, continuous temperature monitoring, current clinical practice often relies on invasive methods (unsuitable for conscious patients) or static, single-time-point measurements that fail to capture the dynamic trajectory of core temperature changes. Furthermore, while preoperative warming is known to reduce heat redistribution, its efficacy when combined with continuous, non-invasive wireless monitoring in laparoscopic colorectal cancer (CRC) surgery requires further investigation.

Methodology
This study was a single-center, prospective, randomized controlled trial (RCT) conducted at the First Affiliated Hospital of Wenzhou Medical University.

• Participants: 180 patients scheduled for elective laparoscopic radical resection of colorectal cancer under general anesthesia were enrolled. Inclusion criteria included ages 18–75, ASA physical status I–III, normal preoperative temperature, and a BMI of 18.5–28 kg/m².
• Intervention Groups: Patients were randomly allocated (1:1) into two groups:
  • Pre-warming Group (P): Received 30 minutes of forced-air pre-warming (38°C) applied to the torso and limbs in the preoperative preparation room, in addition to standard intraoperative warming.
  • Routine Warming Group (C): Received standard care (thin blanket) in the preoperative room, followed by identical intraoperative warming measures.
• Standardized Care: Both groups received identical intraoperative management, including forced-air warming (38°C, adjustable to 43°C if needed), warmed IV fluids and irrigation (38°C), and operating room temperatures maintained between 21°C and 24°C.
• Monitoring Technology: A key methodological feature was the use of the iThermonitor®, a wireless, non-invasive temperature sensor placed in the axilla. This device provided continuous, dynamic temperature monitoring from the preoperative waiting area through the operating room and into the Post-Anesthesia Care Unit (PACU), eliminating the need for measurement tool switching.
• Outcomes: The primary outcome was the incidence of IPH (T < 36°C) between entry to the operating room and departure from the PACU. Secondary outcomes included temperature fluctuations, time to hypothermia onset, duration of hypothermia, recovery metrics (extubation time, PACU stay), complications (shivering, PONV, agitation), pain scores, coagulation parameters, inflammatory markers, and hospitalization costs.
• Statistical Analysis: Analyses were performed using R software. Continuous variables were compared via t-tests or Mann–Whitney U tests; categorical variables via χ² or Fisher's exact tests. Regression models (linear, Poisson, negative binomial, ordinal logistic, and Gamma GLM) were utilized to estimate risk ratios (RR), mean differences (MD), and odds ratios (OR) with 95% confidence intervals.

Key Results

• Hypothermia Incidence: The pre-warming group demonstrated a significantly lower incidence of perioperative hypothermia compared to the routine group (33.3% vs. 76.6%; P < 0.001). The risk ratio for hypothermia in the routine group was 2.30 (95% CI 1.50–3.53).
• Temperature Dynamics: Core body temperatures in the pre-warming group were significantly higher at all perioperative time points from T1 to T9 (P < 0.05). Among patients who did develop hypothermia, the pre-warming group experienced a significantly delayed onset of hypothermia and a significantly shorter duration of hypothermia (P < 0.05).
• Recovery and Complications: The pre-warming group showed significantly better outcomes in:
  • Time to recovery of consciousness and extubation.
  • Incidence of postoperative shivering, agitation, and postoperative nausea and vomiting (PONV).
  • Time to first flatus (indicating faster gastrointestinal recovery).
  • Postoperative pain scores (VAS) and PCA pump usage at 24 hours.
  • Total hospitalization costs (significantly lower in the pre-warming group).
  • Note: No significant differences were observed between groups regarding delayed emergence, PACU length of stay, or coagulation parameters (APTT, PT).
• Inflammatory and Coagulation Markers: There were no significant differences between groups in white blood cell counts, IL-6, IL-10, or acid-base balance (pH, HCO₃⁻) on postoperative day 1.
• Subgroup Analysis: Interaction tests revealed no significant differences in the intervention's effect across subgroups defined by age, sex, BMI, surgery type, or duration, suggesting the benefits of pre-warming are consistent across these variables.

Significance and Claims
The authors claim that combining 30 minutes of preoperative forced-air warming with continuous wireless temperature monitoring (iThermonitor®) effectively reduces both the incidence and severity of perioperative hypothermia in patients undergoing laparoscopic radical colorectal cancer surgery.

The study posits that this approach:

1. Improves Clinical Outcomes: By stabilizing core temperature, pre-warming reduces hypothermia-related complications (shivering, PONV) and accelerates postoperative recovery (earlier extubation, faster return of bowel function).
2. Enhances Economic Efficiency: The reduction in complications and length of stay translates to significantly lower total hospitalization costs.
3. Validates Monitoring Technology: The use of the iThermonitor® allows for accurate, continuous, non-invasive tracking of core temperature dynamics, overcoming the limitations of static measurements and invasive probes.
4. Supports ERAS Protocols: The findings align with Enhanced Recovery After Surgery (ERAS) goals by promoting rapid recovery and reducing the economic burden on healthcare systems.

The authors conclude that while routine intraoperative warming alone is insufficient to prevent hypothermia in this population, the addition of preoperative warming provides a robust, clinically beneficial strategy. They acknowledge limitations, including the single-center design, the specific focus on minimally invasive surgery, and the lack of long-term infection data, calling for future multi-center studies to further validate these findings.