Use of CPAP in ED: a comparison between two different systems

In the ED, CPAP is frequently delivered via Venturi-generators, that afford high flows at a FiO2 that rarely exceedes 50% at the cost of lowering flow and preventing continuous pressure to be maintained. In recent years a different tool, the Boussignac system, that employes multiple O2 jets inside a plastic tube to attain gas flow sufficient to sustain continuous pressures at a FiO2 ranging from 60 to 90%, has been introduced. Aim of this study was to compare the efficacy of these two different systems on a clinical ground. For this purpose we retrospectively evaluated a series of 25 patients consecutively treated in our ED for AHRF. 12 out of them (11 ACPE, 1 CAP: group 1) were treated with a Venturi flow-generator (Vital Signs Vital flow 100, Totowa, NJ, USA), while 13 (9 ACPE, 4 CAP: group 2) underwent CPAP with the Boussignac device (Vygon, Ecouen, France). A PEEP level of 10 Cm H2O was used in both groups. FiO2 was set at 50% in group 1, while for group 2 it was estimated to range from 60 to 90% based on previous experimental studies. For both groups, epidemiologic, clinical and blood gas parameters were recorded at entry. PaO2, PaCO2, Respiratory Rate were recorded at 1 hour of treatment. Duration of treatment (DT), length of stay in the critical care area of the ED (LCC), length of hospital stay (LH) were recorded as outcome results. Data were compared between groups for statistical significance. Finally, all the above parameters were correlated to outcome results for the whole series of patients. In both groups CPAP sorted a significant improvement in PaO2 and RR. However, the improvement of PaO2 was more sensible in group 2, while improvement of RR was more evident in group 1, in wich this parameter tended to be lower at entry. All the patients in group 1 and 7 out of 13 in group 2 required a period of treatment in the critical care area of the ED. DT was shorter in group 2 and the difference was highly significant. At correlation of clinical parameters to outcome results, improvement of PaO2 from baseline to 1 hour of treatment resulted to inversely correlate to DT, while RR at 1 hour directly correlated with LCC. Based on these data, the two devices appear to be comparable in efficacy for the treatment of AHRF in the ED. However, Boussignac CPAP, prompting an higher FiO2, seems to allow a shorter duration of treatment. This may help to optimise the need for critical care utilization in this condition.