Effets hémodynamiques du propofol

Abstract

The new form of propofol gives the same haemodynamic effects as the old one (propofol diluted in cremophor EL). There are few experimental studies concerning the haemodynamic effects of propofol. In the dwarf pig, Glen and Turner found a fall in arterial blood pressure and peripheral resistances, whilst the heart rate and cardiac output rose. In man, studies have shown that propofol gives haemodynamic effects similar to the other intravenous anaesthetic drugs, and especially thiopentone. In subjects with a healthy heart, and for doses included between 1,5 and 2,5 mg · kg −1, propofol gave a 25 to 30% fall in arterial blood pressure. There are also a 20% fall in peripheral resistances and a small fall (10%) in cardiac output. Blood pressure returned to its initial level 3 to 5 min after the injection. The heart rate was not much changed, and rather slowed, perhaps because of central vagotonia. When propofol was used to maintain anaesthesia, either by repeat injections, or by infusion, with the patient breathing spontaneously and not undergoing painful stimuli, blood pressure and heart rate remained steady within 55 to 65% of their initial values. Propofol appeared to avoid to some extent the increase in blood pressure and heart rate seen during intubation. When propofol and fentanyl were used together, the cardiovascular effects were more prononced than when they were used alone. Moreover, propofol appeared to limit to a large extent the hypertension due to intubation and sternotomy in patients undergoing aorto-coronary arterial graft surgery. Initial studies in patients suffering from coronary heart disease asked for a careful use of propofol in these patients, as the fall in arterial diastolic pressure, together with the tachycardia, could lead to a fall in coronary blood flow. However, a recent study has shown that propofol also induced a large fall in the myocardial oxygen consumption. In patients with cardiac failure, propofol only slightly altered the filling pressures. The small reduction in preload, together with the fall in peripheral vascular resistances, reduces the myocardial work load; as a result, propofol could be used in valve surgery.