Pre-operative evaluation for diabetic cardiac autonomic neuropathy and their behavior during regional anesthesia
1.1 Background: CAN (cardiac autonomic neuropathy) is a common form of diabetic neuropathy and causes abnormalities in heart rate control as well as central and peripheral vascular dynamics. There is 2- to 3- fold increase in cardiovascular morbidity and mortality intra-operatively for patients with diabetes. Hemodynamic instability during intra-operative period depends on the severity of autonomic dysfunction. Patients with severe autonomic dysfunction have a high risk of blood pressure instability and intra-operative blood pressure support is needed more often in those with greater impairment. Non-invasive diagnostic methods assessing autonomic function allow identification of patient at risk pre-operatively and better prepare the anesthesiologist for potential hemodynamic changes. This study aimed to evaluate the diabetic patient and control group pre-operatively for cardiac autonomic neuropathy with CANS – 504 (cardiac autonomic neuropathy analyzer) and compare hemodynamic instability in each group during spinal anesthesia
1.2. Methods: We performed cardiac autonomic function study with CANS – 504 in group I (diabetic with autonomic neuropathy) 20 patients, group II (diabetic without cardiac autonomic dysfunction) 20 patients, group III (control group – non diabetic without cardiac autonomic dysfunction ) 20 patients, preoperatively and monitor the blood pressure, pulse rate and ECG in these groups during spinal anesthesia.
1.3. Results: During spinal anesthesia in group I experienced hypotensive reactions and bradycardia significantly more often (75%) than in group II (40%) and group III (18%). In order to achieve stability in B.P the patient in group I had to be given vasoactive drugs much more often (55%) than patients of group II (30%) and those of group III (15%). In group I 33% ar non-reactive to vasoactive drugs and these patients need inotropic support to achieve B.P stability.
1.4. Conclusive: We found a significant correlation between degree of autonomic dysfunction and largest drop in B.P and variability in H.R and cardiac rhythm. These results prove the atypical hemodynamic behavior and extreme instability in B.P in diabetic autonomic neuropathy under spinal anesthesia. Therefore we consider it to be very helpful to check the cardiovascular refectory status of diabetic pre-operatively and may prepare anesthesiologist for potential hemodynamic changes.