No abstract

730CAN J ANESTH 2000 / 47: 8 / pp [730][731][732][733][734][735][736][737][738][739] Purpose: To develop a clinically useful and valid model for predicting difficult laryngoscopic tracheal intubation in patients with seemingly normal airways by adhering to the principles of multivariable model development.Methods: This was an observational study performed at a tertiary-care teaching hospital. Preoperatively, 444 randomly selected patients requiring tracheal intubation for elective surgery were assessed. In addition, 27 patients in whom tracheal intubation was difficult, but were not assessed preoperatively, were assessed postoperatively. One assessor, blinded to the intubation information, collected the predictor variables. A reliable definition for difficult intubation was used and all attempts were made to eliminate sources of bias. Multivariable modeling was performed using logistic regression and the model was validated using the bootstrapping technique.Results: Of the 461 patients included in the analysis, 38 were classified as difficult to intubate. Multivariable analysis identified three airway tests that were highly significant for predicting difficult tracheal intubation. These were: 1) "mouth opening", 2) "chin protrusion", and 3) "atlanto-occipital extension". Using these tests, a validated, highly reliable and predictive model is produced to determine the probability of difficult intubation for patients. At a selected probability cut-off value, the model is 86.8% sensitive and 96.0% specific. Conclusion:A simple and accurate multivariable model, consisting of three airway tests, is produced for predicting difficult laryngoscopic tracheal intubation. Additional studies will be required to determine the accuracy and feasibility of this model when applied to a large sample of new patients by multiple anesthesiologists.Objectif : Élaborer un modèle valide et utilisable en clinique pour prédire des difficultés d'intubation trachéale laryngoscopique chez des patients qui ont apparemment des voies aériennes normales. Utiliser, pour ce faire, les principes d'élaboration d'un modèle multivariable.Méthode : Il s'est agi d'une observation réalisée dans un hôpital d'enseignement de soins tertiaires. Avant l'opéra-tion, on a évalué 444 patients choisis au hasard qui avaient besoin d'intubation endotrachéale pendant une intervention planifiée. De plus, 27 patients chez qui l'intubation a été difficile n'ont été évalués qu'après l'intervention. Un assistant, qui ne connaissait pas les conditions d'intubation, a enregistré les variables de prédiction. Une défi-nition exacte de l'intubation difficile a été utilisée et on a tenté d'éliminer tout biais possible. Une modélisation à multivariables a été réalisée en utilisant une régression logistique et le modèle a été validé par la technique de l'amorce («bootstrapping»).Résultats : Des 461 patients inclus dans l'analyse, 38 ont été difficiles à intuber. L'analyse à multivariables a reconnu trois épreuves d'intubation comme hautement significatives pour prédire une intu...

An episode ofhypotension is common during cemented joint replacement, and has been associated with circulatory collapse and sudden death. We studied the mechanism of hypotension in two groups of six dogs after simulated bilateral cemented arthroplasty. In one group, with no lavage, the insertion of cement and prosthesis was followed by severe hypotension, elevated pulmonary artery pressure, decreased systemic vascular resistance and a 21% reduction in cardiac output. In the other group, pulsatile intramedullary lavage was performed before the simulated arthroplasties. Hypotension was less, and although systemic vascular resistance decreased, the cardiac output did not change. The severity ofthe hypotension, the decrease in cardiac output and an increase in prostaglandin metabolites were related to the magnitude of pulmonary fat embolism. Pulsatile lavage prevents much of this fat embolism, and hence the decrease in cardiac output. The relatively mild hypotension after lavage was secondary to transient vasodilatation, which may accentuate the hypotension caused by the decreased cardiac output due to a large embolic fat load. We make recommendations for the prevention and management of hypotension during cemented arthroplasty.