Renal failure

Effect on drug handling

• Protein-bound drugs have increased free fractions due to acidosis and hypoalbuminaemia
• Lipid-insoluble drugs are excreted renally
• The kidney excretes hepatic metabolites of lipid-soluble drugs
• Uraemia may change the structure and function of drugs

Fluids and electrolytes

• Hypervolaemia
• Oedema
• Hypertension
• Metabolic acidosis
• Hyperkalaemia (may rise with suxamethonium, catabolic stress, acidosis, potassium-sparing diuretics)
• Hypermagnesaemia (inadequate dialysis)
• Hypocalcaemia : 2^o/3^o hyperparathroidism and leading to bone resorption, osteoporosis, osteomalacia and fractures

Medical conditions with uraemia

• Hypertension
• Pericarditis and effusion
• Atherosclerosis and ischaemic heart disease
• Pulmonary oedema
• Atelectasis, pneumonia and adult respiratory distress syndrome
• Depressed immunity
• Poor wound healing
• Peptic ulceration with elevated gastrin - increased risk of aspiration

Anaemia

• Normochromic, normocytic
• 2^o to decreased erythropoietin secretion
• Multiple transfusions increase risk of acquired infection
• Uraemic coagulopathy

Assessment

• Physical status and timing of last dialysis
• Vascular access sites should be noted with reference to any shunts
• Optimal time 24 hours post-haemodialysis but peritoneal dialysis can be carried on until surgery
• Transfusion during dialysis preferably
• Urea and electrolytes: correct hypertension and hyperkalaemia
• Clotting correction

Conduct

• Consider regional anaesthesia
• Avoid lactate-containing solutions
• Patient positioning - re: shunt sites
• Watch fluid status/central venous pressure monitoring
• IV lines away from shunts
• Measure urine output
• Rapid sequence induction due to increased risk of aspiration
• Pre-oxygenation due to anaemia

Drugs

• Suxamethonium may have a prolonged effect and may induce arrhythmias
• Avoid hypotension with induction agents
• Atracurium/vecuronium agents of choice
• Avoid enflurane, as toxic metabolite formed
• Treat hypotension with fluid
• Dopamine may increase renal perfusion

Postoperatively

• Watch for fluid overload
• Dehydration
• Residual neuromuscular blockade
• Watch urea and electrolytes
• Analgesia with regional or carefully titrated opioids