Infrared thermographic assessment of spinal anaesthesia-related cutaneous temperature changes during caesarean section

Infrared thermographic assessment of cutaneous temperature changes during labour epidural analgesia initiation: an observational pilot study

BACKGROUND

Inadequate labour epidural analgesia within 30 to 45 minutes of insertion is typically considered primary epidural failure and deemed unsuccessful. Early prediction of analgesic success would have clinical benefit, enabling corrective interventions. Sympathectomy accompanying a successful epidural block can cause foot temperature changes. We sought to evaluate the relationship between foot temperature changes and successful epidural, defined as adequate analgesia in 45 minutes of epidural administration. For the purpose of this study, we defined primary epidural failure as inadequate analgesia within 45 minutes of administration.

METHODS

Following ethical committee approval, this observational study was conducted in a tertiary level obstetric centre between January 2021 and March 2024. Patients attending for induction of labour were included: those with labour epidural analgesia comprised the epidural study group, and those without served as a control group. A FlirT540 infrared thermography camera was used to take bilateral foot images every 5 minutes for 30 minutes. Images were taken following epidural administration in the epidural group, and at any convenient time once in established labour in the control group. We studied temperature changes over time in the both groups, and compared the temperature changes in patients with successful and failed epidurals.

RESULTS

Thirty-eight patients were included in the epidural group and 11 in the control group. Twenty-nine patients (76.3%) had successful analgesia and nine patients (23.7%) had primary epidural failure. Patients with successful analgesia had a statistically significant rise in temperature after 10 minutes. The maximum rate of increase was between 5 and 15 minutes and was 0.5 (0.1)°C per minute on both sides. Primary epidural failure was associated with minimal temperature changes, while all patients who had a 2°C rise in hallux temperature at 10 minutes had successful analgesia.

CONCLUSIONS

Sympathetic blockade associated with a successful analgesic epidural block produces cutaneous temperature elevation at the plantar surface of the hallux. These can be detected within 10 minutes of epidural administration and have a potential role in guiding timely troubleshooting of an unsuccessful epidural.

Observational study of peripheral skin temperature changes following spinal anaesthesia for caesarean birth

BACKGROUND

Spinal anaesthesia is widely used in obstetric anaesthesia practice but there is limited knowledge about the development of sympathetic blockade following spinal anaesthesia for caesarean birth. This study investigated the characteristics of sympathetic blockade by measuring peripheral skin temperature changes in the feet of patients given spinal anaesthesia for elective caesarean birth.

METHODS

A prospective observational study was conducted involving 60 eligible parturients scheduled for elective caesarean birth with spinal anaesthesia. Skin temperature probes were attached to the dorsum of both feet, and temperature measurements were recorded every minute. The dose of spinal anaesthesia given, and other relevant patient data, were collected.

RESULTS

All participants had successful spinal anaesthesia. Following spinal anaesthesia, a sustained rise in skin temperature of both feet was observed, indicating the presence of sympathetic blockade. The maximum rate of temperature increase occurred between 6 and 15 min after the intrathecal injection and plateaued from 22 min after the injection. Control participants did not show any changes in foot temperature.

CONCLUSIONS

This study demonstrates that successful spinal anaesthesia for caesarean birth results in a consistent and reliable rise in skin temperature of the feet that is evident after six minutes from intrathecal injection. The observed temperature changes provide indirect objective evidence of bilateral sympathetic blockade. Measurement of feet skin temperatures may serve as an additional objective indicator of successful spinal anaesthesia, along with tests of lower limb motor block and sensory block height. These findings contribute to the understanding of sympathetic blockade during spinal anaesthesia.