Correlation between the Perfusion Index and Intraoperative Hypothermia: A Prospective Observational Pilot Study

The Correlation Between Preoperative Perfusion Index and Intraoperative Hypothermia During Laparoscopic Radical Surgery for Urological Malignancies

This study aimed to explore the relationship between preoperative baseline perfusion index (PI) and intraoperative hypothermia during general anesthesia. PI reflects the peripheral perfusion status, which may be associated with the decrease of core temperature during general anesthesia, as the redistribution of temperature from the core compartment to the peripheral compartment depends on the peripheral perfusion status. A total of 68 patients underwent radical surgery for urological malignancies in this study. The baseline PI value was measured upon entering the operating room. Core temperature was continuously monitored using a nasal pharyngeal probe from anesthesia induction to the end of surgery, with temperature data recorded every 15 minutes. Univariate and multivariate logistic regression analyses were used to identify risk factors for intraoperative hypothermia. Intraoperative hypothermia occurred in 26 patients, whose baseline PI (2.70 ± 0.73) was significantly lower than that of the normothermic group (3.65 ± 1.05), with P<0.05. The baseline PI was independently associated with intraoperative hypothermia (PI: [OR] 0.375, 95% confidence interval [CI]: 1.584-6.876, p = 0.001). This study suggests that low baseline PI is an independent factor associated with intraoperative hypothermia. In future studies, PI value could be considered as a predictor for the treatment of intraoperative hypothermia.

Relationship between perfusion index and central temperature before and after induction of anesthesia in laparoscopic gastrointestinal surgery: A prospective cohort study

The perfusion index (PI) cutoff value before anesthesia induction and the ratio of PI variation after anesthesia induction remain unclear. This study aimed to clarify the relationship between PI and central temperature during anesthesia induction, and the potential of PI in individualized and effective control of redistribution hypothermia. This prospective observational single center study analyzed 100 gastrointestinal surgeries performed under general anesthesia from August 2021 to February 2022. The PI was measured as peripheral perfusion, and the relationship between central and peripheral temperature values was investigated. Receiver operating characteristic curve analysis was performed to identify baseline PI before anesthesia, which predicts a decrease in central temperature 30 minutes after anesthesia induction, and the rate of change in PI that predicts the decrease in central temperature 60 minutes after anesthesia induction. In cases with a central temperature decrease of ≥ 0.6°C after 30 minutes, the area under the curve was 0.744, Youden index was 0.456, and the cutoff value of baseline PI was 2.30. In cases with a central temperature decrease of ≥ 0.6°C after 60 minutes, the area under curve was 0.857, Youden index was 0.693, and the cutoff value of the PI ratio of variation after 30 minutes of anesthesia induction was 1.58. If the baseline PI is ≤ 2.30 and the PI 30 minutes after anesthesia induction is at least 1.58-fold the PI ratio of variation, there is a high probability of a central temperature decrease of at least 0.6°C within 30 minutes after 2 time points.

Association between preoperative toe perfusion index and maternal core temperature decrease during cesarean delivery under spinal anesthesia: a prospective cohort study

Background

The main mechanism of body temperature decrease during cesarean delivery under spinal anesthesia is core-to-peripheral redistribution of body heat, attributable to vasodilation. Perfusion index (PI) obtained with a pulse oximeter helps to assess peripheral perfusion dynamics by detecting the change in peripheral vascular tone. This study aimed to examine whether preoperative toe PI could predict the decrease in core temperature induced by spinal anesthesia during cesarean delivery.

Methods

Parturients undergoing scheduled cesarean delivery under combined spinal-epidural anesthesia from September 2019 to March 2020 were enrolled in this single-center prospective cohort study. All parturients received 0.5% hyperbaric bupivacaine (10 mg) with fentanyl (15 μg) intrathecally. A pulse oximeter probe was placed on the left second toe for continuous PI measurement. The 3 M™ Bair Hugger™ Temperature Monitoring System placed over the right temporal region was used to record core temperature over time. We evaluated the association between the maximum core temperature decrease, which is the primary outcome, and the preoperative toe PI at operating room (OR) admission using a segmented regression model (SRM) and a generalized additive model (GAM). The maximum core temperature decrease was defined as the difference between core temperature at OR admission and minimum intraoperative core temperature.

Results

Forty-eight patients were evaluated. In the SRM, the slope for the association between the maximum core temperature decrease and the preoperative toe PI changed from 0.031 to 0.124 after PI = 2.4%. Likewise, with the GAM, there was a small core temperature decrease when preoperative toe PI was greater than 2.0 to 3.0%.

Conclusions

Low preoperative toe PI was associated with maternal core temperature decrease during cesarean delivery under spinal anesthesia. Preoperative toe PI is a simple, non-invasive, and effective tool for the early prediction of perioperative core temperature decrease during cesarean delivery.

Trial registration

UMIN Clinical Trials Registry (registry number: UMIN000037965).