---

Diabetic Nephropathy: Anaesthetic Considerations

(MD Anaesthesia Examination Format)

---

1. DEFINITION & CLASSIFICATION

---

2. PATHOPHYSIOLOGY RELEVANT TO ANAESTHESIA

• Reduced GFR → impaired drug/metabolite excretion → prolonged drug action
• Proteinuria → hypoalbuminaemia → altered protein binding → higher free drug fraction
• Reduced tubular acid excretion → metabolic acidosis
• Impaired water and sodium handling → fluid overload or dehydration
• Impaired erythropoietin synthesis → normochromic normocytic anaemia

• Hypertension in >80% of patients
• Accelerated atherosclerosis → IHD, silent myocardial infarction (autonomic neuropathy masks angina)
• Left ventricular hypertrophy (from hypertension) → diastolic dysfunction
• Cardiomyopathy (diabetic + uraemic)
• Pericarditis/pericardial effusion in ESRD
• Prolonged QTc, arrhythmias

• Peripheral neuropathy (sensorimotor) - affects regional technique consent and positioning
• Autonomic neuropathy: gastroparesis (aspiration risk), orthostatic hypotension, resting tachycardia, impaired cardiovascular response to hypoxia and haemodynamic stress, bladder dysfunction
• Central neuropathy: uraemic encephalopathy in advanced disease

• Anaemia of CKD (normochromic normocytic)
• Uraemic platelet dysfunction (thrombocytopathy) - normal PT/APTT does not exclude coagulopathy
• Increased risk of thromboembolic events

• Compensatory hyperventilation for metabolic acidosis (Kussmaul respiration)
• Pulmonary oedema (fluid overload)
• Pleural effusions

• Hyperkalaemia (most immediately life-threatening)
• Hyponatraemia
• Metabolic acidosis (high anion gap)
• Hypocalcaemia, hyperphosphataemia
• Hypomagnesaemia
• Uraemic syndrome: nausea, vomiting, altered sensorium, pericarditis, pruritus, myopathy

• "Burnt-out diabetes" phenomenon: up to 1/3 of dialysis patients have spontaneous improvement in glycaemic control (reduced insulin requirements), risk of unexplained hypoglycaemia
• HbA1c may be falsely low in ESRD (shortened RBC lifespan, dialysis interference)

• Stiff joint syndrome ("prayer sign"): glycosylation of atlanto-occipital joint in 30-40% of diabetics - limited neck mobility, difficult intubation
• Cheiropathy affects atlantoaxial joint

---

3. PREOPERATIVE ASSESSMENT

History

• Duration and type of diabetes, glycaemic control (HbA1c, recent glucose logs)
• Stage of nephropathy; if on dialysis: modality, frequency, last session, volume removed
• Medications: antihypertensives, diuretics, insulin/OHAs, immunosuppressants, steroids
• Cardiovascular history: chest pain (may be silent), heart failure, prior MI, PVD
• Symptoms of autonomic neuropathy: postural symptoms, gastroparesis, voiding difficulty
• Arteriovenous fistula site (must be protected)

Examination

• Airway: restricted mouth opening, "prayer sign" (inability to appose palms suggests difficult airway), mallampati score
• Blood pressure (both arms), pulse character
• Fluid status: JVP, peripheral oedema, lung auscultation
• Neurological: peripheral sensation, reflexes
• Vascular access: examine AV fistula patency; avoid blood pressure, cannulae, or tourniquet on fistula arm

Investigations

Optimisation Before Elective Surgery

• Correct hyperkalaemia: K+ >5.5-6.0 mmol/L is absolute contraindication to elective surgery
• Correct acidosis (target HCO3- >18 mmol/L)
• Treat anaemia (target Hb >10 g/dL; erythropoietin, iron, blood transfusion if needed - but be careful of volume overload and sensitisation)
• Optimise blood pressure (<140/90 mmHg)
• Optimise glycaemic control (target glucose 6-10 mmol/L perioperatively; 4-12 mmol/L acceptable range)
• Dialysis timing: if patient is on haemodialysis, schedule surgery the day after dialysis; allow >6 hours after HD (heparin effect wears off in ~4 hours); avoid same-day surgery after HD if possible
• Treat fluid overload/pulmonary oedema
• Stop nephrotoxic drugs pre-operatively (NSAIDs, aminoglycosides, contrast agents)

Medication Management

• ACE inhibitors/ARBs: Continue controversially - may cause refractory intraoperative hypotension; decision individualised. Most centres hold on day of surgery if patient is not on them for heart failure
• Metformin: Stop 48 hours before surgery (risk of lactic acidosis, especially if contrast is used or haemodynamic instability)
• SGLT-2 inhibitors: Stop 3-4 days before surgery (risk of euglycaemic DKA; Empagliflozin, Dapagliflozin, Canagliflozin)
• GLP-1 agonists (Semaglutide, Liraglutide): Stop 1 week before surgery (delayed gastric emptying exacerbated by these drugs; aspiration risk - recent 2023-2024 guidance)
• Insulin: Dose adjustment as per hospital protocol (GKI - glucose-potassium-insulin infusion, or Basal-Bolus protocol)
• Diuretics: Continue (except on morning of surgery if K+ or BP are already at risk)
• Antihypertensives: Continue most (beta-blockers and calcium channel blockers should be continued)

---

4. INTRAOPERATIVE MANAGEMENT

Choice of Anaesthesia

• Avoids airway manipulation (relevant if difficult airway expected)
• Maintains renal perfusion better than GA in many cases
• Avoids hepatic/renal drug metabolism issues
• BUT: pre-existing peripheral neuropathy - document baseline neurological deficits before block; obtain informed consent that neuropathy may worsen (medico-legally important)
• Autonomic neuropathy: sympathectomy from spinal/epidural exaggerates hypotension - pre-hydrate cautiously, have vasopressors ready (phenylephrine or noradrenaline preferred over ephedrine which relies on intact sympathetic store)
• Coagulopathy assessment mandatory before neuraxial techniques

• Rapid Sequence Induction (RSI) if gastroparesis is present (common in autonomic neuropathy) - cricoid pressure, thiopentone or propofol + suxamethonium or modified RSI with rocuronium + sugammadex availability
• Suxamethonium: SAFE if pre-op K+ is within normal range (<5.5 mmol/L); raises K+ by ~0.5 mmol/L - use cautiously if K+ is borderline
• Propofol: safe in CKD/ESRD; pharmacokinetics not significantly altered
• Thiopentone: increased free fraction (hypoalbuminaemia) - reduce dose by 30-50%
• Ketamine: increased cardiovascular side effects in hypertensive CKD patients; use with caution
• Etomidate: suitable for haemodynamically unstable patients (adrenal suppression risk with single dose is less of a concern perioperatively)

• Anticipate difficult laryngoscopy (stiff joint syndrome, limited neck mobility)
• Have difficult airway trolley available
• Video laryngoscope as primary/backup

• Volatile agents (sevoflurane, desflurane, isoflurane): all safe at clinical doses in CKD/ESRD
  • Sevoflurane: produces Compound A (nephrotoxic in animal models, not clinically significant at low-flow >2 L/min fresh gas); generally considered safe
  • Desflurane and isoflurane: no nephrotoxic potential
• Total intravenous anaesthesia (TIVA) with propofol: safe; remifentanil ideal as metabolised by non-specific plasma esterases (not renal-dependent)
• Nitrous oxide: avoid (expands closed air spaces, bowel distension in uraemic ileus, diffuses into pericardial effusion)

• Use neuromuscular monitoring (TOF) throughout - essential in CKD
• Sugammadex: preferred reversal agent over neostigmine (predictable reversal); caution in severe CKD - sugammadex-rocuronium complex accumulates (but generally safe for single perioperative use)

• Maintain strict normovolaemia - CKD patients poorly tolerate both hypovolaemia (worsening AKI) and hypervolaemia
• Avoid excessive 0.9% NaCl (hyperchloraemic metabolic acidosis)
• Hartmann's/Lactate Ringer's: Contains 4 mmol/L K+ - use cautiously in hyperkalaemia, but generally safe in normovolaemic CKD
• Plasmalyte: Buffered, K+ 5 mmol/L; balanced; reasonable choice
• Colloids (albumin, starches): Avoid HES (hydroxyethyl starch) - nephrotoxic, worsens outcome in CKD; albumin can be used in specific indications
• Avoid unnecessary blood transfusions (sensitisation, volume overload) - use cell salvage

• Standard ASA/AAGBI monitoring: SpO2, NIBP, ECG, ETCO2, temperature
• Invasive arterial line: for major surgery, haemodynamic instability, frequent glucose/ABG monitoring
• Central venous pressure: guide fluid therapy (but alone is not a reliable predictor of fluid responsiveness)
• Urine output monitoring: >0.5 mL/kg/hr; oliguria may not be reliable indicator in CKD (baseline low output)
• TOF monitoring: essential
• Temperature: hypothermia worsens drug metabolism and platelet function (already impaired)
• Continuous blood glucose monitoring: target 6-10 mmol/L (avoid hypoglycaemia)

• Avoid hypotension (most important cause of acute-on-chronic kidney injury in perioperative period)
• MAP >65-70 mmHg (use preoperative baseline as reference)
• Vasopressors for refractory hypotension: Noradrenaline preferred (direct alpha agonist); phenylephrine acceptable; ephedrine less reliable in autonomic neuropathy (depleted sympathetic stores)
• Avoid abrupt hypertension (LVH predisposes to diastolic dysfunction, acute cardiac failure)

• Maintain adequate renal perfusion pressure
• Avoid nephrotoxic drugs (aminoglycosides, NSAIDs, contrast agents)
• Avoid ACE inhibitors in the immediate perioperative period if possible
• Avoid prolonged NSAID use for analgesia
• Careful positioning to avoid renal vascular compression
• Minimise duration of hypotension

---

5. POSTOPERATIVE MANAGEMENT

Analgesia

• Paracetamol: Safe (hepatic metabolism); first-line adjunct
• NSAIDs: AVOID - worsen renal function (inhibit prostaglandin-mediated afferent arteriolar vasodilatation)
• Regional/neuraxial techniques: Preferred for postoperative analgesia if feasible
• Opioids: Use remifentanil infusions or fentanyl PCA (with caution); avoid morphine, pethidine; monitor for excessive sedation
• Gabapentinoids (pregabalin, gabapentin): Require significant dose reduction in renal failure (renally excreted); risk of excessive sedation

Recovery

• Extended monitoring in HDU/ICU for major surgery or poor baseline function (GFR <30)
• Supplemental oxygen: CKD patients slow to emerge; continued SpO2 monitoring
• Strict fluid balance charting
• Electrolyte monitoring: K+, Na+, HCO3- in recovery
• Resume dialysis post-operatively as per renal team guidance
• Monitor for acute-on-chronic kidney injury (rising creatinine, falling UO)

Glycaemic Control

• Target perioperative glucose: 6-10 mmol/L
• Avoid hypoglycaemia (dangerous in already autonomically impaired patients with impaired hypoglycaemia awareness)
• GKI (Glucose-Potassium-Insulin) infusion or Basal-Bolus protocol
• Monitor glucose 1-2 hourly

Resume Medications

• Restart antihypertensives when haemodynamically stable
• Restart insulin/OHA as tolerated orally
• Delay restarting metformin until renal function confirmed stable (48-72 hours post-op)
• Delay SGLT-2 inhibitors until eating and drinking normally post-op

---

6. SPECIFIC CONSIDERATIONS BY SCENARIO

Patient on Haemodialysis (ESRD)

• Schedule surgery the day after HD; allow >6 hours after HD (heparin effect)
• Protect AV fistula arm at all costs (no BP, IV, tourniquet on that arm)
• Post-op dialysis as needed
• High risk of hyperkalaemia, fluid overload, and haemodynamic instability

Perioperative Dialysis

• HD removes many drugs (aminoglycosides, water-soluble drugs, vancomycin) - redose after dialysis
• Continuous renal replacement therapy (CRRT) in ICU for haemodynamically unstable patients

Emergency Surgery in Uncontrolled DN

• Risks: hyperkalaemia, acidosis, fluid overload, uraemic coagulopathy, aspiration
• Correct K+ acutely: calcium gluconate, insulin-dextrose, sodium bicarbonate, resonium, salbutamol nebulisation, dialysis if available
• RSI mandatory
• Choose cisatracurium + remifentanil-based TIVA

---

7. SUMMARY TABLE: KEY DRUG RECOMMENDATIONS

---

8. EXAM MEMORY AID

• D - Dialysis timing and AV fistula protection
• I - Intubation difficulty (stiff joint syndrome)
• A - Anaemia correction + Autonomic neuropathy assessment
• B - Blood glucose target 6-10 mmol/L; HbA1c unreliable
• E - Electrolytes (K+ < 5.5 mandatory); Echocardiogram if needed
• T - Thrombocytopathy (uraemic platelet dysfunction); Toxaemia of uraemia
• I - Inotropes/Vasopressors (noradrenaline > ephedrine)
• C - Cisatracurium + Remifentanil (safe drug pair in CKD)
• N - No NSAIDs, No morphine, No pethidine, No HES
• E - Extra monitoring: TOF, arterial line, glucose
• P - Propofol safe; Protein binding altered (reduce doses)
• H - Hypotension avoidance = kidney protection

---

• Chronic kidney disease and anaesthesia (BJA Education, PMC) - PMID 36097571
• Perioperative Management of Patients With ESRD - Kanda et al., J Cardiothorac Vasc Anesth 2017
• UpToDate: Anesthesia for patients with diabetes mellitus (updated Feb 2025)
• Barash, Cullen & Stoelting's Clinical Anesthesia, 9e
• KDIGO CKD guidelines