There are various concepts that help explain the diagnosis and management of ICU patients, who often have a degree of similar physiology – including shock and systemic Inflammatory response syndrome. This very often results in organ system dysfunction/failure, often starting with one organ and sometimes progressing to multi-organ failure.

ICU patients are a varied group including trauma, various medical conditions (heart failure, pneumonia, stroke, epilepsy, diabetic coma, sepsis from any cause, thromboembolism) surgical conditions including postoperative complications, and chemotherapy related problems.

Oxygen delivery (DO2 ) is a key concept here, described by a simplified delivery equation,

DO2 = cardiac output × SaO2 × [Hb].

Cardiac output (CO) is the product of stroke volume (SV) and heart rate (HR), so the equation can be rewritten:

DO2 = SV× HR × SaO2 × [Hb]

Which gives four areas to target optimization.

Sepsis is a common cause of clinical problems. It requires rapid management of ‘the sepsis six’: blood lactate measurement, blood cultures, intravenous antibiotics, administration of oxygen, intravenous fluids and urinary output measurement.