Importancia de las variables pre-analíticas en la calidad de la medición de los gases arteriales / Influence of pre analytical variables in the quality of arterial blood gas determination

Three hundred and nine consecutive arterial blood samples received at the central laboratory of a public hospital were analyzed. Patient data in the order form, reception conditions at the laboratory, transport media, time of arrival and analysis of each sample were recorded. Five percent of orders informed the hour of sampling 0.6 percent the patient's temperature and 18.1 percent the inspirated oxygen fraction. Bubbles or clots were present in 12.9 percent and 3.2 percent of samples respectively; 87.3 percent of samples were well sealed and the amount of blood withdrawn in relation to the syringe capacity was optimal in 47.2 percent of cases. Ninety three percent of syringes were transported with ice cubes that did no cover the syringe and 5.8 percent of samples were received at room temperature. The delay in analysis, since the time of reception at the laboratory, ranged from 0 to 55 min (mean 12.9 min). Several deficiencies in pre analytical variables in blood gas analysis were identified, most caused by neglect and susceptible of correction. Quality controls for this determination should be performed frequently