Background & Objectives: Patients with diabetes are at increased risk of complications and death in the peri-operative period compared to non-diabetics. Cardiac autonomic neuropathy (CAN) is a frequent complication of type 1 and 2 diabetes, attenuating the compensatory response of the cardiovascular system to anaesthesia. The resulting hypotension may lead to ischemia of vital organs. We hypothesize that the presence of CAN is associated with peri-operative hypotension.
The purpose of this study is to investigate the utility of pre-operative screening for CAN to predict peri-operative hypotension and the vasopressor need amongst diabetic patients.
Materials & Methods: Diabetic patients undergoing elective surgery in general- or spinal anaesthesia are recruited into a double-blinded cross-sectional study. The presence of CAN is investigated days to weeks prior to surgery by internationally accepted standard tests: i) heart rate variability during 5 minutes´ rest (HRV-5), ii) paced breathing, iii) posture change, and iv) Valsalva’s maneuvre.
Current medication, type, duration and possible late complications of diabetes are recorded. The patient’s blood pressure is measured non-invasively on both arms. Peri-operative data are extracted from the anaesthesia record.
Results: We present data (mean ±sd) from 26 diabetic patients, of whom 22 had type 2 diabetes. The average age and BMI were 62±9 years and 31±6 kg/m2, respectively. All patients underwent general anaesthesia. The preliminary analysis show an association between HRV-5 and hypotension during the induction of anaesthesia (i.e. from the administration of a sedative bolus medication and the subsequent 10 minutes). Linear regression analysis showed that a lower HRV-5 was associated with a greater decrease in blood pressure (P=0.01).
When stratified by low, medium, and high HRV-5, the lowest measured mean arterial blood pressure (MAP) was 58±18, 60±9, 71±14 mmHg, respectively. Furthermore, patients with a dip in MAP below 60 mmHg tended to have a lower HRV-5 compared to the other patients (P=0.06). The remaining CAN tests were not associated with MAP.
Conclusion: The preliminary results show that peri-operative hypotension is associated with HRV-5. Once the study is completed, we are able to assess the utility of CAN screening to predict peri-operative hypotension. If successful, a pre-operative screening for CAN may aid the planning of cardiovascular monitoring during anaesthesia.
1.Huang et al. Pre-operative measurement of heart rate variability predicts hypotension during general anesthesia. Acta Anaesthesiol Scand. 2006 May;50(5):542–8
2.Vinik et al. Diabetic autonomic neuropathy. Diabetes Care. 2003 May;26(5): 1553–79.
Disclosure of Interest: None declared