Table 1.

Adverse effects of acute postoperative pain

Physiological
Cardiovascular
•↑ Sympathetic-nervous-system activity •Tachycardia •Hypertension •↑ Myocardial O2 demand •↓ Myocardial O2 supply •Risk of cardiac ischaemia
Respiratory
•↓ Ability to cough •↓ Functional residual capacity •Atelectasis •Ventilation: perfusion imbalance •Hypoxaemia
Gastrointestinal
•↓ GI motility •Ileus
Endocrine
•↑ Catabolic hormones (cortisol, adrenocorticotrophic hormone, growth hormone, catecholamines, angiotensin 2, and glucagon) •↓ Anabolic hormones (insulin and testosterone)
Renal
•Sodium and water retention (↑ catecholamines, ↑ activation of renin–angiotensin–aldosterone system, ↑ antidiuretic hormone) •↑ Excretion of potassium
Haematological
•↓ Cellular and humoral immune function •Hypercoagulable state
Metabolic
•Insulin resistance, ↓ insulin secretion •↑ Gluconeogenesis, ↑ glycogenolysis, hyperglycaemia •Muscle catabolism •↑ Lipolysis
Psychological
•Anxiety •Disrupted sleep •Social isolation •Helplessness •Pain catastrophisation •Risk factor for developing chronic post-surgical pain