M. Bertrand

Hématome sous-dural aigu après soustraction–drainage du LCR par voie lombaire chez deux patients opérés d’anévrismes thoraco-abdominaux

Resume Le drainage–soustraction du liquide cephalorachidien (LCR) par voie lombaire pour prevenir les accidents medullaires de la chirurgie des anevrismes thoraciques ou thoraco-abdominaux (AT/ATA), fait l’objet d’un veritable engouement parmi les equipes prenant en charge ce type de patients. Alors que le benefice de cette technique fait encore l’objet de discussion, nous rapportons deux accidents a type d’hematome sous-dural (HSD) retarde chez deux de nos patients, apres application de cette technique. Le clampage de l’aorte entraine une baisse brutale et severe de la pression de perfusion medullaire, une augmentation de la pression intracrânienne et par les modifications de repartition du retour veineux, une augmentation de la pression du liquide cephalorachidien. Cette derniere entraine une diminution de la pression de perfusion medullaire. La soustraction de LCR vise a ameliorer la perfusion medullaire puisqu’elle retablit une pression de perfusion proche de la normale. Les deux cas cliniques rapportes viennent s’ajouter au passif d’une methode de prevention du risque medullaire qui, pour seduisante qu’elle soit, n’a pas encore fait la preuve de son efficacite a diminuer la frequence et/ou la gravite des accidents medullaires de la chirurgie des AT/ATA. En l’etat actuel, cette technique devrait etre reservee aux patients chez qui le rapport benefice/risque est favorable, soit en corollaire aux patients a risque medullaire connu, documente par exemple par une arteriographie medullaire. La mise en place et le retrait du catheter doivent se faire dans les conditions habituelles de ponction medullaire, pour ce qui concerne les traitements anticoagulants et antiplaquettaires.

Retentissement hémodynamique du clampage de la carotide chez l'opéré coronarien

: To determine both the incidence of myocardial ischaemia and haemodynamic response to carotid cross-clamping in coronary artery disease, 30 patients undergoing carotid endarterectomy were studied with a clear history of effort related disabling angina pectoris. Myocardial ischaemia was detected by a recording of lead CM5 of the electrocardiogram. A radial arterial and a thermodilution pulmonary catheter were inserted to obtain haemodynamic measurements before and after carotid cross-clamping and unclamping. Anaesthesia was induced with increments of thiopental, fentanyl 6 micrograms X kg-1 and pancuronium. Additional fentanyl (2 micrograms X kg-1) was injected before skin incision and before carotid cross-clamping. Carotid cross-clamping results in a significant increase in both mean arterial blood pressure and capillary wedge pressure. Two patients experienced myocardial ischaemia with ST segment depression during carotid cross-clamping. Nitroglycerin infusion led to the improvement of ST segment depression. When halothane was additionally administered to patients who developed hypertension in response to carotid cross-clamping, arterial blood pressure returned to normal value. These results indicate that carotid cross-clamping increases determinants of myocardial oxygen demand and may cause myocardial ischaemia in patients suffering from angina pectoris.

Thrombopénie croisée aux héparines et au danaparoïde

Resume Les thrombopenies d’origine allergique (TIH) et croisees a l’heparine non fractionnee (HNF) et aux heparines de bas poids moleculaire (HBPM) sont connues, et la prise en charge des patients atteints assez bien codifiee. L’arret de la ou des heparines suspectes est imperatif. Un des traitements substitutifs aux heparines est le danaparoide (Orgaran®). Cette molecule est pourtant a l’origine de thrombopenies, parfois croisees avec les heparines. Cette observation permet de rappeler cette possibilite rare mais reelle.

Etude de l'activité baroréflexe lors de l'endartériectomie carotidienne sous anesthésie générale

The baroreceptor reflex was studied in eleven patients, aged 69 ± 6 years, scheduled for carotid endarterectomy under general anaesthesia. Nine were hypertensive. The anaesthetic protocol was the same for all the patients : premedication with morphine and scopolamine, induction with 5 mg · kg−1 thiopentone, 6 μg · kg−1 fentanyl and 0.01 mg · kg−1 pancuronium bromide. All the patients were intubated and ventilated with a mixture of nitrous oxide and oxygen. Fentanyl, 100 μg, was routinely given at the time of incision. Baroreflex sensitivity was tested using Smyths method, with a bolus of 75 μg trinitrin and plotting changes in heart rate against those in systolic blood pressure. Electrocardiogramme, invasive arterial blood pressure and airway pressure were simultaneously recorded. Paco2 and Pao2 were measured during arterial clamping. The tests were carried out before clamping, 2 min later and 10 to 20 min after the last injection of fentanyl. In the seven patients for whom clamping lasted more than 15 min, a further test was carried out after administration of 0.4 ± 0.05 vol % halothane (Datex analyser) for 5 min. During anaesthesia, baroreflex sensitivity was low (1.8 ± 0.3 ms · mmHg−1). After clamping, there was only a significant change in Pasys, with no changes in heart rate or blood gas values (129 ± 8 mmHg before clamping ; 167 ± 12 mmHg after clamping ; n = 8 ; p < 0.01). After halothane administration, the sensitivity slope decreased, but not significantly. Moreover, halothane decreased the R-R intervals (1140 ± 84 after clamping ; 963 ± 76 under halothane ; n = 6 ; p < 0.05). In patients undergoing carotid endarterectomy under general anaesthesia, baroreflex sensitivity was reduced ; this was probably mainly due, not only to the various anaesthetic drugs used, but also to the chronic hypertension, the age of the patients and the atheromatous disease.