Preoperative autonomic function assessment as a predictor of post induction hypotension in diabetic patients undergoing elective surgeries

Diabetes mellitus is a prevalent chronic disease in India, leading to multiple anesthetic challenges including cardiovascular instability and autonomic dysfunction. Diabetic autonomic neuropathy impairs cardiovascular reflexes and predisposes patients to severe post-induction hypotension (PIH), which is associated with poor perioperative outcomes including acute renal damage, major adverse cardiac events, and increased mortality risk. Current evidence regarding the predictive value of autonomic function tests for PIH in diabetic patients remains insufficient.

Aim

To assess whether preoperative autonomic function tests can predict post induction hypotension in diabetic patients undergoing elective surgeries under general anaesthesia.

Primary Objective

To assess the correlation  betweenvariables derived from  three autonomic function tests - Electrochemical Skin Conductance (ESC), Baroreceptor Sensitivity (BRS), and Heart Rate Variability (HRV) - with incidence of post induction hypotension in diabetic  patients undergoing elective surgeries under general anaesthesia.

Secondary Objectives

1. To determine the incidence of Post-Induction Hypotension (arterial hypotension occurring during the first 20 minutes after anesthesia induction)
2. To determine the incidence of Early Intraoperative Hypotension (arterial hypotension up to 30 minutes post-incision)
3. To evaluate the need and amount of vasopressor administration to correct hypotension

Methodology

This single-center prospective observational cohort study will enroll 214 diabetic patients (ASA I-III, aged 18-80 years) undergoing elective surgery under general anesthesia. Participants will undergo three non-invasive autonomic function tests one or 2 days  before surgery: Electrochemical skin conductance (ESC) via Sudoscan®, Heart rate variability(HRV) analysis, and Baroreceptor sensitivity test (BRS) testing. During surgery, standardized monitoring will record hemodynamic parameters every 2 minutes for 20 minutes post-induction and 30 minutes post-incision. Hypotension is defined as MAP <65 mmHg, SBP <90 mmHg, or 30% drop in MAP from baseline.

Outcome Measures

1. To derive CAN score using electrochemical skin conductance ,high and low frequency power in baroreflex sensitivityand time domain and frequency domain paramaters in heart rate variability test.
2. To determine the incidence of post induction hypotension (PIH),i.e. arterial hypotension occuring during first 20 mins after anesthesia induction.
3. To determine the incidence of early intraoperative hypotension(eIOH), i.e. arterial hypotension upto 30 mins post incision.
4. To assess the correlation between variables derived from three autonomic function tests- Baroreceptor sensitivity(BRS),Heart rate variability(HRV) and Electrochemical skin conductance(ESC) with incidence of post induction hypotension.
5. To evaluate the need and amount of vasopressor administration to correct hypotension