This study was performed to evaluate the understanding of an increased alveolar-arterial oxygen gradient (Aa-gradient) among hospital-based health care professionals in an university-affiliated teaching hospital.
A common clinical scenario was chosen with a setting of “pure” oxygen inhalation (FiO2 of 1.0) and a “normal” arterial PO2 of 100 mm Hg with a pCO2 of 40 mm Hg. One hundred subjects, consisting of students, medical residents, fellows of different subspecialties, attendings, nurses and respiratory therapists, were interviewed. Evaluation with and without a personal digital assistant device (PDA)-based Aa-gradient program was performed (MedCalc 2001). A subgroup of twenty individuals was randomized with a coin toss. The study group was unbiased and had no prior knowledge of the study question. EpiInfo, version 6, Statcalc, was used for evaluation.
Of the randomized 20 subjects, 10 out of 10 individuals had correct answers with the use of a PDA. Only 2 out of 10 subjects estimated an Aa-gradient of greater than 200 without prior PDA use (p = 0.0003, confidence interval 1.5-17.3). A scatter plot shows the estimated A-a gradient (AaDO2) and the level of education. The mean estimated Aa-gradient was 128 with a range of 0-500. Four subjects stated that they did not know the answer and 7 individuals were excluded because of prior knowledge of the study results.
Appreciation of the large Aa-gradient in patients with a pO2 of 100 on FiO2 of 1.0 was not evident. Increased awareness is useful because an Aa-gradient of 563 is potentially fatal if adequate intervention is not undertaken. The PDA-based program significantly improved awareness of acute lung injury and acute respiratory distress syndrome.
A real-time PDA-based Aa-gradient program increases the appreciation of acute lung injury and acute respiratory distress syndrome. This may change the aggressiveness of the diagnostic and therapeutic approach to critically ill patients.
S. Amanullah, None.