[A study of blood loss during surgery for scoliosis. Posterior approach in 319 adolescents]. / Etude du saignement dans la chirurgie de la scoliose. Interventions par voie postérieure chez 319 adolescents.

A retrospective study including 319 patients was realized from 1984 to 1993 in order to evaluate during scoliosis surgery the incidence on bleeding of the type of scoliosis and the anesthetic procedure. Blood losses were below one litre thus reducing the homologous blood transfusions. The patient was in prone position on a modified Wilson frame which facilitates venous return from the dorsal region. A moderate controlled hypotension was realized by combination of halothane, intravenous nitroglycerin (NG) and beta-blocking drugs (when required). Somatosensory evoked potentials were continuously monitored during surgery. A compression of the dorsal region was realized postoperatively in order to reduce blood loss. The blood losses were compared using Student's t-test. The mean perioperative bleeding was 9.8 ml.kg-1 for idiopathic scoliosis (no transfusion required), 14.1 ml.kg-1 for secondary scoliosis (p < 0.05 vs idiopathic) and 29.3 ml.kg-1 for neuromyopathic scoliosis (p < 0.05 vs idiopathic), indicating a major influence of muscle atonia on bleeding. The moderate controlled hypotension by iterative injection of NG and beta-adrenergic blocking drugs provided a safe and reversible hypotension.

[In vitro and in vivo effects of propofol on the hemoglobin dissociation curve]. / Effets du propofol sur la courbe de dissociation de l'oxyhémoglobine in vivo et in vitro.

This study assessed in vivo and in vitro the effects of propofol on the affinity of hemoglobin for oxygen in seven ASA 1 adults. For the in vivo study, venous blood samples were withdrawn before and after premedication, after the injection of 2.5 mg.kg-1 of propofol and after 15 minutes of maintenance at an infusion rate of 0.2 mg.kg-1.min-1. For the in vitro study, propofol was added to the blood withdrawn before premedication in order to obtain two samples at a concentration of 1 microgram.mL-1 and 2 micrograms.mL-1 respectively. Propofol changed neither in vivo, nor in vitro, the P50 and the number of Hill indicating the angle of the slope of the dissociation curve, nor in vivo the concentration of 2,3-DPG.