Hypotensive anesthesia with isoflurane and enflurane during total hip replacement: a comparative study of catecholamine and renin angiotensin responses.

Catecholamine and renin-angiotensin responses to enflurane- or isoflurane-hypotensive anesthesia were compared in a randomized study. Two groups of 10 patients undergoing total hip arthroplasty were premedicated with morphine hydrochloride (0.1 mg/kg). Anesthesia was induced with thiopental and the trachea intubated after pancuronium. Equal concentrations of each volatile agent (1.3 MAC) were administered until mean arterial blood pressure decreased to 50-60 mm Hg. Hemodynamic data and blood samples for measurements of plasma renin activity (PRA) and plasma epinephrine (E) and norepinephrine (NE) concentrations were collected 1) after induction and intubation but before the start of isoflurane or enflurane; 2) 15 min (T15) after the start of isoflurane or enflurane administration; and 3) 45 min (T45) after the start of isoflurane or enflurane administration. The desired level of hypotension was achieved at T15 with isoflurane and at T45 with both anesthetics. When hypotension was achieved, cardiac index and stroke index were significantly lower in the enflurane group while systemic vascular resistance index was lower in the isoflurane group. Increases in E and NE levels above baseline levels were significantly greater in the isoflurane group than in the enflurane group. Use of isoflurane to induce hypotension is associated with more rapid induction of hypotension, less depression of cardiac output, and better preservation of homeostatic responses than is use of enflurane.

[Hemodynamic monitoring in microneurosurgical excision by sub- and retro-sinus approach in seated position in acoustic neurinoma]. / Surveillance hémodynamique au cours de l'exérèse micro-neurochirurgicale par voie sous- et rétrosinusienne en position assise du neurinome de l'acoustique.

Haemodynamic data (thermodilution Swan-Ganz catheter and radial artery cannula) were collected in 17 patients (52.4 +/- 8 yr) during retrosigmoid approach for removal of an acoustic tumour in the seated position. Measurements were made before stimulation of posterior fossa structures (period 1) and during tumour dissection along the brain stem (period 2). Significant increases in systolic, diastolic and mean blood pressures, in pulmonary capillary wedge pressure, in cardiac index and in stroke index were observed during period 2, whereas heart rate, right atrial pressure and systemic vascular resistances were unaffected. The greater the size of the tumour and the difficulties in dissection, the greater were these intraoperative haemodynamic changes. In addition, the pulmonary arterial blood temperature and the noradrenaline plasma concentrations (double isotope enzymatic assay) increased significantly during period 2. In conclusion, the prolonged microsurgical technique of acoustic tumour dissection through the retrosigmoid approach may modify left ventricular loading conditions and may lead to pulmonary oedema, even if intravascular volume expansion was minimal and ventricular function was near normal.