Pulse oximetry-based perfusion index as a non-invasive indicator of systemic hemodynamics during spinal anesthesia in cesarean delivery

Abstract

Background & Objectives: Placental perfusion is not autoregulated and is susceptible to effects of spinal anesthesia (SA) induced hypotension. The perfusion index (PI) is a non-invasive marker of peripheral vascular tone, and a higher PI indicates increased risk of hypotension following SA. This study aims to establish preoperative baseline PI in our local population and its correlation with incidence of intraoperative hypotension.

Methods: This prospective observational study recruited 35 parturients who underwent elective lower segment cesarean section (LSCS). Preoperatively, baseline heart rate (HR), systolic blood pressure (SBP), mean arterial pressure (MAP) and PI were documented. SA was performed with 8 to 10 mg of injection bupivacaine 0.5% (hyperbaric) at L3–L4 interspace followed by co-loading with 1 L Hartmann solution. Hypotension was defined as SBP less than 80% of baseline or less than 90 mmHg. A bolus of phenylephrine 50 µg was given as rescue medication to treat the hypotension. Intraoperatively, degree of decrease in SBP, MAP and HR, as well as the amount of phenylephrine required was recorded every minute until delivery of the baby and 3 min thereafter.

Results: The correlations between parturients’ baseline PI with the degree of decreases in systolic and mean arterial pressure (r = 0.81, P < 0.001 and r = 0.76, P < 0.001, respectively) and phenylephrine requirement (r = 0.761, p < 0.005) were recorded. This study identified that the patients with cut-off PI value of 3.2 were at higher risk for SA induced hypotension with a sensitivity of 85.9% and a specificity of 87.5% (P = 0.001).

Conclusion: The patients with baseline cut-off perfusion index value of more than 3.2 were at higher risk for spinal anesthesia induced hypotension in elective cesarean section.

Abbreviations: CO - cardiac output; LSCS - lower segment cesarean section MAP - mean arterial pressure; PI - perfusion index; SA - spinal anesthesia

Keywords: Hypotension; Pulse Oximeter; Perfusion Index; Spinal Anesthesia; Cesarean section;

Citation: Manap NSA, Zaini RHM, Shukeri WFWM, Omar SC, Abu Bakar MZ, Seevaunnamtum P. Pulse oximetry-based

perfusion index as a non-invasive indicator of systemic hemodynamics during spinal anesthesia in cesarean delivery. Anaesth. pain intensive care 2024;28(5):927−932; DOI: 10.35975/apic.v28i5.2570

Received: July 23, 2024; Reviewed: September 02, 2024; Accepted: September 10, 2024