Effect of Preoperative Prewarming on Serum Lactate Levels in Patients Undergoing Elective Nephrectomy

Effect of Preoperative Active Prewarming on Serum Lactate Levels and Perioperative Outcomes in Patients Undergoing Elective Nephrectomy: A Prospective Observational Study

The goal of this observational study is to learn whether warming patients before surgery, called "prewarming," affects blood lactate levels (a marker of how well tissues are getting oxygen) and recovery in adults having planned (elective) kidney removal surgery (nephrectomy).

The main questions this study aims to answer are:

• Does prewarming lower the rise in blood lactate seen during and after surgery?
• Does prewarming affect time spent in the intensive care unit (ICU), the need for a blood transfusion, or the rate of complications after surgery?

Researchers will compare two groups of adults having this surgery. One group receives brief active warming before anesthesia (the "prewarming" group). The other group does not receive this warming (the "control" group). The anesthesia team decides whether to use prewarming and for how long, as part of routine care; the study does not change this decision. Researchers will compare the two groups to see whether prewarming is linked to lower lactate levels and better recovery.

Participants will:

• Receive their usual, routine surgery and anesthesia care
• Have blood pressure, heart rate, body temperature, and blood tests, including lactate, checked before and after surgery, as already done in routine care
• Have their ICU stay, need for blood transfusion, and any complications recorded

This study does not add any extra tests, procedures, or blood draws beyond routine clinical care.

Study Overview

• Status: Recruiting
• Conditions: Hyperlactatemia; Intraoperative Hypothermia; Nephrectomy / Methods
• Intervention / Treatment: Device: Preoperative active warming (prewarming)

Detailed Description

Nephrectomy is a major surgical procedure, performed via open or laparoscopic approaches, that is associated with a substantial physiological stress response. Reduced tissue perfusion and increased anaerobic metabolism during major surgery can raise serum lactate levels, and maintaining perioperative metabolic stability is an important goal in these patients.

Prewarming refers to active warming of a patient's body surface before induction of anesthesia, with the aim of reducing intraoperative core-temperature drop and its downstream effects on tissue perfusion and oxygenation. Clinical practice regarding the use and duration of prewarming varies among anesthesiologists, and there is no fixed institutional protocol dictating whether, or for how long, it should be applied.

This is a prospective, single-center, observational study conducted over a one-year period. Consecutive adult patients undergoing elective nephrectomy who meet the eligibility criteria will be enrolled and followed as part of routine clinical care (see Eligibility Criteria for full details). Whether a given patient receives prewarming, and for how long (typically 10-15 minutes when used), is determined solely by the anesthesia team providing care in the operating room; the study does not intervene in this clinical decision or modify usual care in any way. Outcomes will be compared between patients who receive prewarming and those who do not.

For each patient, a range of preoperative and postoperative physiological and laboratory parameters is recorded as part of routine perioperative monitoring (see Outcome Measures for the specific parameters and their timing). In addition, length of stay in the intensive care unit, need for blood transfusion, and the occurrence and type of postoperative complications are documented. All data are obtained from existing anesthesia records, nursing charts, laboratory results, intensive care information systems, and patient files, and are transcribed onto a predefined case report form; the study does not add any invasive procedures, blood draws, or deviations from routine clinical protocol.

Continuous variables will be compared between the prewarming and control groups using the independent-samples t-test or Mann-Whitney U test, as appropriate, and categorical variables will be compared using the chi-square test or Fisher's exact test. Regression analysis will be used to examine associations between prewarming and outcomes. A p-value <0.05 will be considered statistically significant. A power analysis (G*Power v3.1.9.2), assuming a medium effect size (Cohen's d=0.5) for the primary between-group lactate comparison, indicated that at least 64 participants per group (128 total) would be needed to achieve 80% power at α=0.05.

• Study Type: Observational
• Enrollment (Estimated): 128

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Sisli
    • Istanbul, Sisli, Turkey (Türkiye), 34384
      • Recruiting
      • Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization
      • Contact: Mehmet Mutlu, Assoc. Prof.; Phone Number: +905363458888; Email: drmmutlu@gmail.com

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Adult patients aged 18-90 years, ASA I-III, undergoing elective nephrectomy (open or laparoscopic) at the study site, enrolled consecutively over a one-year period.

Description

Inclusion Criteria:

• Scheduled for elective nephrectomy
• Adults aged 18-90 years
• ASA (American Society of Anesthesiologists) physical status classification I-III
• Signed informed consent form

Exclusion Criteria:

• Emergency nephrectomy
• Concurrent additional major surgical procedure planned in the same session
• Age under 18 or over 90 years
• ASA physical status classification IV or higher
• Incomplete preoperative records (missing pre- or postoperative measurement of at least one primary outcome variable)

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Prewarming Group; Patients who receive active preoperative warming, applied by the anesthesia team during operating room preparation, typically for approximately 10-15 minutes before induction of anesthesia, as part of routine clinical care.	Device: Preoperative active warming (prewarming); Application of an active warming device to the patient's body surface during operating room preparation, before induction of anesthesia, for approximately 10-15 minutes at the discretion of the anesthesia team. The decision to apply prewarming, and its duration, follows routine clinical practice and is not standardized by the study protocol.; Other Names: Active preoperative warming
Control Group; Patients who do not receive active preoperative warming before induction of anesthesia, per the routine practice of the anesthesia team providing care. All patients receive standard intraoperative and postoperative warming per usual care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Serum Lactate Concentration	Change in serum lactate concentration from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Systolic and Diastolic Blood Pressure	Changes in systolic and diastolic arterial blood pressure from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Change in Heart Rate	Change in heart rate from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Change in Body Temperature	Change in body temperature from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Change in Hemoglobin Level	Change in hemoglobin concentration from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Change in Hematocrit	Change in hematocrit from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Change in Serum Osmolality	Change in serum osmolality from the preoperative assessment to the postoperative assessment, compared between the prewarming and control groups.	From the preoperative assessment to 24 hours after surgery
Length of Intensive Care Unit Stay	Duration of stay in the intensive care unit, compared between the prewarming and control groups.	Up to 48 hours after surgery
Need for Blood Transfusion	Proportion of patients requiring blood transfusion and the total number of units transfused during the first 48 hours after surgery, compared between the prewarming and control groups.	During the first 48 hours after surgery
Incidence of Postoperative Complications	Presence and type of postoperative complications (respiratory, cardiac, renal, infectious, hematologic, or other), compared between the prewarming and control groups.	From surgery to 24 hours after surgery

Collaborators and Investigators

• Sponsor: Beyzanur Aydoğdu

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2025
• Primary Completion (Estimated): November 15, 2026
• Study Completion (Estimated): November 15, 2026

Study Registration Dates

• First Submitted: July 7, 2026
• First Submitted That Met QC Criteria: July 10, 2026
• First Posted (Actual): July 14, 2026

Study Record Updates

• Last Update Posted (Actual): July 14, 2026
• Last Update Submitted That Met QC Criteria: July 10, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative complications; Intensive care unit; Anesthesia; Nephrectomy; prewarming; Perioperative hypothermia; serum lactate; Preoperative warming
• Additional Relevant MeSH Terms: Pathologic Processes; Metabolic Diseases; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Postoperative Complications; Hyperlactatemia
• Other Study ID Numbers: CT-ERHO-AR-BA-03; E-48670771-514.99-293554897 (Other Identifier: PROF. DR. CEMIL TASCIOGLU SEHİR HASTANESİ ETİK KURUL BİRİMİ)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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