Carefully & constantly monitor CV & resp vital signs & state of consciousness; level of anesth; ECG in patients treated w/ anti-arrhythmic drugs class III (eg, amiodarone). May cause acute toxicity effects on CNS & CVS. Ventricular arrhythmia/fibrillation, sudden CV collapse & death w/ high systemic conc. Increased risk of high or total spinal blockade in elderly & in late stages of pregnancy. Hypotension & bradycardia. Massive ascites, large abdominal tumors or late pregnancy; cardiac decompensation; hypovolemia. Intercostal paralysis; resp embarrassment in patients w/ pleural effusions. Increased risk of intraspinal abscess formation in the post-op period w/ septicemia. Ageing or other compromising factors eg, partial or complete heart conduction block, advanced liver or renal dysfunction. CV & resp depression. Neurological disorders eg, multiple sclerosis, hemiplegia, paraplegia & neuromuscular disorders. Pregnancy. Elderly.