Diabetic autonomic neuropathy is a critical complication frequently encountered in anaesthetic and surgical practice. Power spectral analysis is a noninvasive tool for monitoring frequency analysis of heart rate variability (HRV) and autonomic control of the heart. This study examined HRV changes in preoperative diabetic patients without overt signs of autonomic dysfunction and in matched controls (n=18 per group). HRV values at -15 degrees, 0 degrees, 15 degrees, 45 degrees and sitting positions were compared between groups and for each position. HRV in diabetic patients was lower than in controls at all positions (absolute units). Low-frequency power (normalized units) and the low-frequency/high-frequency ratio increased significantly at 45 degrees and in sitting positions in controls but not in diabetic patients. Pre-existing autonomic derangements in diabetic patients without overt clinical symptoms can be aggravated by high-degree tilting or sitting positions. Consequently, great care should be taken during the intra- and perioperative management of these patients.
This study investigated the effect of local anaesthetic temperature on block of the first sacral segment. Twenty-four patients undergoing lumbar epidural anaesthesia at L2-3 or L3-4 were randomly divided in double-blind fashion into two groups to receive 22 ml of lignocaine 2% with adrenaline 1:200,000, sodium bicarbonate and fentanyl, at either 21°C (cold group) or 37°C (warm group). The sensory block was assessed by loss of sensation to pinprick and the pain threshold after repeated electrical stimulation at L2, S1 and S3 dermatomes. Motor block was evaluated using the modified Bromage scale. Patient characteristics were comparable between the groups. Onset of block at the first sacral segment (S1) was faster in the warm group than in the cold (10 vs 17.5 minutes, P <0.001). The pain threshold at S1 was significantly higher in the warm group. We concluded that epidural lignocaine 2% with adrenaline 1:200,000, sodium bicarbonate and fentanyl injected at 37°C hastens S1 block within 10 minutes of administration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.