Table 2.

Clinical examples of postoperative complications

Grade	Organ system	Example
1	Cardiac	Arrhythmia cardioconverting with electrolytes
	Respiratory	Fluid overload requiring diuretics
	Neurological	Mild delirium, self-limiting
	Gastrointestinal	Drug-related diarrhoea
	Renal	Mild acute renal failure (not requiring treatment)
2	Cardiac	Atrial fibrillation requiring ß-blockade/digoxin
	Respiratory	Pneumonia needing antibiotics and/or oxygen
	Neurological	Transient ischaemic attack
	Gastrointestinal	Ileus needing nasogastric/further treatment
	Renal	Urinary tract infection needing antibiotics
3a	Cardiac	Bradyarrhythmia needing pacing wire
	Respiratory	Effusion needing chest drain
	Neurological	Extra/subdural haematoma needing evacuation
	Gastrointestinal	Pseudo-obstruction needing flatus tube
	Renal
3b	Cardiac	Tachyarrhythmia needing direct current cardioversion
	Respiratory	Bronchopleural fistula post thoracic surgery
	Neurological	Extra/subdural haematoma needing evacuation
	Gastrointestinal	Anastomic leakage needing surgery
	Renal	Stenosis of ureters after transplantation
4a	Cardiac	Heart failure requiring ionotropes
	Respiratory	Pneumonia needing intubation
	Neurological	Cerebrovascular accident/haemorrhage
	Gastrointestinal	Pancreatitis
	Renal	Acute renal failure
4b		Any combination of the above

Adapted from [11].