Forced-Air Warming for Preventing Perioperative Hypothermia During Total Knee Arthroplasty

Effect of Intraoperative Forced-air Warming on Perioperative Hypothermia and Related Complications in Patients Undergoing Total Knee Arthroplasty: A Historical Control Study

Perioperative hypothermia is a common complication during total knee arthroplasty (TKA) and may increase the risk of shivering, delayed anesthetic recovery, and postoperative complications. This historical control study aims to evaluate the effectiveness and safety of intraoperative forced-air warming in preventing perioperative hypothermia in patients undergoing primary unilateral TKA.

A total of 240 patients were included. Patients in the historical control group received routine passive warming measures, while patients in the intervention group received additional forced-air warming during the perioperative period. Core body temperature, incidence of inadvertent perioperative hypothermia, anesthetic recovery outcomes, postoperative complications, and safety outcomes were evaluated.

Study Overview

• Status: Completed
• Conditions: Total Knee Arthroplasty; Perioperative Hypothermia
• Intervention / Treatment: Device: Forced-Air Warming; Other: Routine Passive Warming

Detailed Description

This single-center historical control study was conducted at Shanghai 6th People's Hospital between May 2018 and December 2018 to evaluate the effectiveness of intraoperative forced-air warming for preventing perioperative hypothermia in patients undergoing total knee arthroplasty (TKA).

A total of 240 patients undergoing primary unilateral TKA were enrolled and divided into two groups according to the study period. Patients enrolled between May 2018 and August 2018 were assigned to the historical control group and received routine passive warming measures, including warmed intravenous fluids, warmed irrigation fluids, operating room temperature control, and cotton blanket coverage. Patients enrolled between September 2018 and December 2018 were assigned to the intervention group and received additional active warming using a forced-air warming system during the perioperative period.

The forced-air warming system was initiated 30 minutes before anesthesia induction and continued until transfer to the post-anesthesia care unit (PACU). Core temperature was continuously monitored using a temperature-sensing urinary catheter.

The primary outcomes included perioperative core temperature changes and the incidence of inadvertent perioperative hypothermia, defined as core temperature below 36°C at any perioperative time point. Secondary outcomes included postoperative shivering, emergence agitation, anesthetic recovery time, blood loss, postoperative complications, and safety outcomes including skin burns and surgical site infection.

This study was approved by the Ethics Committee of Shanghai 6th People's Hospital (Approval No. 05.12.19035). Written informed consent was obtained from all participants before enrollment.

• Study Type: Interventional
• Enrollment (Actual): 240
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200233
      • Shanghai 6th People's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age between 60 and 85 years
• ASA physical status I or II
• Diagnosed with knee osteoarthritis
• Undergoing first unilateral primary total knee arthroplasty
• Able to provide written informed consent

Exclusion Criteria:

• Abnormal coagulation function (international normalized ratio >1.2)
• Preoperative body temperature >37.5°C or <36°C
• Cognitive or psychiatric disorders affecting communication
• Moderate or severe anemia
• Body mass index >30 kg/m² or <18.5 kg/m²
• Moderate or severe malnutrition
• Surgery duration longer than 4 hours
• Intraoperative blood loss greater than 500 mL
• Transfer to surgical intensive care unit after surgery

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Forced-Air Warming Group; Participants received routine passive warming measures plus active warming using a forced-air warming system during the perioperative period.	Device: Forced-Air Warming; Active perioperative warming using a forced-air warming system initiated 30 minutes before anesthesia induction and continued until transfer to the post-anesthesia care unit.
Active Comparator: Routine Warming Group; Participants received routine passive warming measures including warmed fluids, operating room temperature control, and cotton blanket coverage.	Other: Routine Passive Warming; Routine perioperative warming measures including warmed intravenous fluids, warmed irrigation fluids, operating room temperature control, and cotton blanket coverage.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Inadvertent Perioperative Hypothermia	The proportion of participants with core body temperature below 36.0°C at any perioperative time point.	From anesthesia induction to 90 minutes after anesthesia completion
Perioperative Core Temperature Change	Core body temperature measured using a temperature-sensing urinary catheter at predefined perioperative time points.	From operating room entry to 90 minutes after anesthesia completion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Shivering	Incidence and severity of postoperative shivering assessed using a 0-4 shivering scale.	From the end of surgery to 24 hours postoperatively
Emergence Agitation	Incidence and severity of emergence agitation assessed using the Richmond Agitation-Sedation Scale (RASS, -5 to +4), where higher positive scores indicate greater agitation.	From 30 minutes after surgery to 2 hours postoperatively
Anesthetic Recovery Time	Recovery outcomes including awakening time, extubation time, and PACU length of stay.	From the end of anesthesia to 2 hours postoperatively
Intraoperative Blood Loss	Estimated blood loss recorded during the surgical procedure.	During surgery
Postoperative Complications	Incidence of postoperative complications including delirium, nausea and vomiting, cardiac adverse events, skin burns, and surgical site infection.	From the end of surgery to 30 days postoperatively

Collaborators and Investigators

• Sponsor: Shanghai 6th People's Hospital
• Investigators: Principal Investigator: Danling Fang, RN, Shanghai 6th People's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2018
• Primary Completion (Actual): December 31, 2018
• Study Completion (Actual): January 31, 2019

Study Registration Dates

• First Submitted: May 13, 2026
• First Submitted That Met QC Criteria: May 21, 2026
• First Posted (Actual): May 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 21, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Total Knee Arthroplasty; Temperature Management; Anesthesia Recovery; Forced-Air Warming; Perioperative Hypothermia
• Other Study ID Numbers: TKA-FAW-2018-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be publicly shared because the study involves retrospective clinical data and institutional privacy restrictions.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No