What did the study look at?
Hip arthroscopy (keyhole surgery on the hip joint using a camera) is a relatively long procedure during which large volumes of irrigation fluid flow through the joint. These fluids are usually stored at room temperature and are cooler than the body. A fall in core body temperature below 36°C during surgery is called intraoperative hypothermia.
The main aim was to test whether heated irrigation fluid prevents hypothermia. The secondary aims were to see whether core temperature measured rectally differs from temperature measured at the temple, and which method picks up changes more quickly.
How was it done?
This was a prospective randomised controlled trial (level of evidence 2), registered at ClinicalTrials.gov. Patients aged 18 to 50 scheduled for a first hip arthroscopy for femoroacetabular impingement syndrome (bony shapes that pinch the hip joint) between October 2021 and October 2023 were included.
- A coin toss assigned patients to room-temperature fluid (60 patients) or fluid heated to 36-38°C (56 patients).
- All operations took place in the same theatre, set each morning to 19°C, with a warming blanket placed under the patient.
- Body temperature was measured every 15 minutes both with a rectal probe and with a laser thermometer at the temple. A reading below 36°C by either method was counted as hypothermia.
- Episodes of fast heart rate (above 100 beats per minute, tachycardia) during surgery were also reviewed from the records.
What did it find?
- The groups were similar in age, sex, type of anaesthesia, length of surgery and volume of fluid used.
- Hypothermia occurred in 32 patients (53.3%) with room-temperature fluid and in 24 patients (42.9%) with heated fluid. The difference was not statistically significant (P = .425). Across all patients, the rate was 48.3%.
- Of the 56 patients with hypothermia, it was first detected by the rectal probe in 54 and by the temple measurement in 2.
- Rectal measurement detected hypothermia after a mean of 69.6 ± 47.2 minutes, compared with 138.2 ± 56.8 minutes at the temple (P < .001).
- Tachycardia was more frequent (30.8% vs 4.0%) and lasted longer in patients who developed hypothermia.
- No major or minor complications were recorded.
The authors also discuss whether, because every case was detected rectally and the fluid collects below the abdomen, a temporary regional fall in temperature around the hip might be involved, and say this deserves further study.
The authors' conclusion
The authors conclude that using either room-temperature or heated irrigation fluid did not influence the incidence of hypothermia. Rectal measurement of core body temperature detected hypothermia earlier during hip arthroscopy.
Limitations
- The study was carried out at a single centre by a single surgeon; results may differ in other theatre settings.
- There was no control group to show whether hip arthroscopy itself, rather than other factors related to surgery or anaesthesia, caused the hypothermia.
- No gold-standard method (pulmonary artery catheter) was used to check the accuracy of the two measurements, which risks overestimating hypothermia.
- Long-term complications and clinical results were not examined, and the wide variation in operating time may have diluted the findings.
Reference
Fırat A, Veizi E, Kalaycı İ, Sezgin BS, Erdoğan Y, Gürsoy S, Capurro-Soler B, Koutserimpas C. (2025). Heated Irrigation Fluids Did Not Reduce the Prevalence of Rectally Measured Hypothermia During Hip Arthroscopic Surgery Compared With Room-Temperature Fluids: A Prospective Randomized Trial. Orthopaedic Journal of Sports Medicine, 13(6): 23259671251350401. ClinicalTrials.gov: NCT05396924. Licence: CC BY-NC-ND 4.0.
DOI: 10.1177/23259671251350401
Free full text: PubMed Central (PMC12202897)
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
