Assess intravascular volume and
electrolyte imbalances, especially potassium. Correct all anomalies
preoperatively. Systematic review of cardiovascular and respiratory status
(clinical, ECG, chest radiographs, echocardiography, arterial blood gas analysis).
Investigations: CBC (note severity of anemia), clotting times, urea, creatinine, and
electrolytes, liver function tests. The effects of sedative drugs for
premedication are unpredictable because of the changes in plasma protein
levels and the altered pH.