Sympathetic blockade via epidural anaesthesia significantly increased photoplethysmography-derived total and pulsatile tissue blood volume in the toes, while decreasing compliance in the fingers.
Observational
Does epidural anaesthesia-induced sympathetic blockade alter total and pulsatile tissue blood volume as measured by photoplethysmography?
Photoplethysmography can detect haemodynamic changes following sympathetic blockade during epidural anaesthesia, potentially aiding in assessing anaesthesia depth and managing vascular adverse effects.
Epidural anaesthesia, used for pain relief, is based on blocking the sensory and the sympathetic nerves in the lower part of the body. Since the sympathetic nervous system regulates blood vessel diameter, the sympathetic block is also associated with several haemodynamic changes. In the current study photoplethysmography (PPG) was measured on toes and fingers of patients undergoing epidural anaesthesia. Three parameters, which are related to the change in total and pulsatile tissue blood volume, were derived from the PPG baseline and amplitude. All parameters showed statistically significant increase in the toes after the sympathetic block, indicating higher arterial and venous blood volume and higher pulsatile increase in the arterial blood volume (higher arterial compliance) in the toe. These haemodynamic changes originate from the lower tonus of the arterial and venous wall muscles after the sympathetic block. In the fingers the PPG parameters based on the change in PPG amplitude decreased after the sympathetic block, indicating lower compliance. The measurement of the haemodynamic changes by PPG enables the assessment of the depth of anaesthesia, and can help control the adverse effects of the blockade on the vascular system.
Babchenko et al. (Tue,) conducted a observational in Patients undergoing epidural anaesthesia. Epidural anaesthesia (sympathetic blockade) vs. Baseline was evaluated on Changes in total and pulsatile tissue blood volume derived from PPG baseline and amplitude. Sympathetic blockade via epidural anaesthesia significantly increased photoplethysmography-derived total and pulsatile tissue blood volume in the toes, while decreasing compliance in the fingers.