Étude pilote portant sur la concordance entre l'osmolarité calculée et l'osmolalité mesurée des solutions d'alimentation parentérale

Resume Objectif : Comparer l’osmolarite calculee et  l’osmolalite mesuree de toutes les solutions d’ali­mentation parenterale preparees durant une journee de production. Methodologie : Il s’agit d’une etude pilote reali­see au departement de pharmacie du CHU Sainte-Justine en collaboration avec la Faculte de pharma­cie de l’Universite de Montreal. L’osmolarite calculee est obtenue a partir de notre outil informatise de gestion des ordonnances d’alimentation parenterale. L’osmolalite mesuree decoule de la moyenne des deux mesures obtenues par abaissement du point de congelation (Micro-Osmette) pour chaque echan­tillon de solution parenterale preparee durant une journee de production. Resultats : Vingt-sept sacs prepares le 6 mai 2009 ont ete retenus. Trente-trois pour cent des sacs de nutrition parenterale evalues ont une osmolalite fi­nale inferieure a 1000 mOsm/kg (n = 9). La difference relative entre les valeurs d’osmolarite calculees et les valeurs d’osmolalite mesurees varie entre 0 % et 48 % (mediane de 9 %). On observe que cette diffe­rence relative semble inferieure pour les solutions de moins de 1000 mOsm/kg lorsqu’on la compare aux solutions dont l’osmolalite mesuree est supe­rieure 1000 mOsm/kg. Conclusion : Cette etude pilote demontre que les valeurs d’osmolarite calculees, estimees par l’outil informatise de gestion des ordonnances d’alimenta­tion parenterale, sont majoritairement inferieures aux valeurs d’osmolalite mesurees. L’ecart observe entre les valeurs d’osmolarite calculees et d’osmola­lite mesurees varie en fonction de la composition de chaque solution. Cette difference doit etre prise en compte lors de la prescription de solutions d’alimen­tation parenterale. Abstract Purpose: To compare calculated osmolarity with measured osmolality of all total parenteral nutrition solutions prepared for one day of production. Methods: This pilot study was done at the phar­macy department of the CHU Sainte-Justine, to­gether with the Universite de Montreal faculty of pharmacy. Calculated osmolarity was determined using our computerized tool for management of to­tal parenteral nutrition prescriptions. Measured os­molality results from the average of the two values obtained by freezing point depression (Micro-Os­mette) for each sample of parenteral solution prepa­red during one production day. Results: Twenty-seven bags that were prepared on May 6 2009 were selected. Thirty-three percent of total parenteral nutrition bags had a final osmolality value that was less than 1000 mOsm/kg (n=9). The relative difference between calculated osmolarity values and measured osmolality values varied between 0% and 48 % (median of 9%). We observed that this relative difference seemed inferior for solu­tions with an osmolality of less than 1000 mOsm/kg, when compared to solutions with a measured osmo­lality superior to 1000 mOsm/kg. Conclusion: This pilot study demonstrates that the calculated osmolarity values that were estimated by a computerized total parenteral nutrition pres­cription management tool are largely inferior to the measured osmolality values. The observed devia­tion between calculated osmolarity and measured osmolality values varied as a function of the content of each solution. This difference must be conside­red when prescribing total parenteral nutrition solu­tions. Key words: total parenteral nutrition; osmolarity; osmolality; pediatrics; neonatology