Intraoperative Management of Diabetic Autonomic Neuropathy

1. Recognise the Clinical Picture Before Induction

Assess preoperatively by asking about postural dizziness and early satiety. Test HR variability during deep breathing (normal >10 bpm at 6 breaths/min). — Morgan & Mikhail's Clinical Anesthesiology, p. 1410

2. Cardiovascular Instability — the Core Intraoperative Threat

• Intraoperative hypotension requiring vasopressor support (increased risk)
• Exaggerated pressor response to laryngoscopy/intubation — sympathetic overflow without normal buffering
• Perioperative cardiorespiratory arrest — well-documented risk
• Wide heart rate and BP fluctuations, especially during high-stress portions (intubation, surgical stimulation, reperfusion)
• Silent myocardial ischaemia — ST changes may occur without symptoms

"Diabetic patients with autonomic neuropathy are at increased risk for intraoperative hypotension requiring vasopressor support, as well as perioperative cardiorespiratory arrest. There may be an exaggerated pressor response to tracheal intubation." — Barash's Clinical Anesthesia, p. 4043

• Invasive arterial line before induction (especially if cardiovascular disease is present) — allows beat-to-beat BP monitoring and ABG/glucose sampling
• Attenuate the intubation pressor response: lignocaine IV, opioid blunting, or beta-blocker where indicated
• Have vasopressors ready at induction: phenylephrine or norepinephrine infusions; set up before anaesthetic delivery
• Avoid or cautiously use regional/neuraxial techniques: sympathetic block from spinal/epidural can precipitate severe hypotension in patients who already have autonomic insufficiency — if used, titrate slowly and have vasopressors pre-drawn
• Maintain perioperative beta-blockade and statins if the patient is on them

3. Hypoglycaemia Detection is Blunted

• Monitor blood glucose every 1–2 hours intraoperatively (finger-stick or continuous glucose monitor)
• Target: 140–180 mg/dL (avoid both hypoglycaemia and tight control)
• Treat hypoglycaemia (<80–100 mg/dL) with 25 g IV glucose (50 mL of 50% dextrose)
• If on insulin pump: pump suspends automatically, so less glucose correction may be needed
• Avoid assuming tachycardia or BP changes are due to "light anaesthesia" — exclude hypoglycaemia first

"Patients with diabetic autonomic neuropathy or treated with beta blockers may have attenuated hyperadrenergic signs [of hypoglycaemia]." — Miller's Anesthesia, p. 4229

4. Aspiration Risk from Gastroparesis

• Use rapid sequence induction (RSI) as the default airway approach
• Consider oral non-particulate antacid (sodium citrate) preoperatively
• Metoclopramide or erythromycin can be given preoperatively to enhance gastric motility and empty solid food particles
• Autonomic function tests may predict solid food in the stomach but NOT increased gastric volume or acidity — do not rely solely on them

5. Hypothermia Risk

• Active warming (forced-air warming blanket, warm IV fluids)
• Monitor core temperature continuously
• Hypothermia worsens coagulopathy, cardiac irritability, and insulin resistance — keep normothermic

6. Airway — Stiff Joint Syndrome

• Assess the "prayer sign" preoperatively (inability to appose palmar surfaces of fingers)
• Prepare for difficult airway — have video laryngoscope or fibreoptic scope available

7. Choice of Anaesthetic Technique

• All anaesthetic techniques are acceptable in diabetics; technique is dictated by surgery
• Regional/neuraxial: advantageous (reduces sympathetic stress response) BUT dangerous in DAN patients due to compounded sympatholysis — titrate slowly, have vasopressor infusion ready
• General anaesthesia: balanced technique with volatile agent + opioid + muscle relaxant is standard
• Peripheral neuropathy patients may be sensitive to local anaesthetics and have prolonged nerve block duration — reduce dose accordingly

8. Monitoring Summary

• Barash's Clinical Anesthesia, 9th ed., pp. 4042–4043
• Miller's Anesthesia, 10th ed., pp. 4228–4230
• Morgan & Mikhail's Clinical Anesthesiology, 7th ed., pp. 1410–1414