The Effect of Filters on CPAP Delivery by Helmet.

BACKGROUND: When helmet CPAP is performed using a Venturi system, filters are frequently interposed in the respiratory circuit to reduce noise within the helmet. The effect of the interposition of these filters on delivered fresh gas flow and the resulting FIO2 is currently unknown. METHODS: In a bench study, 2 different Venturi systems (WhisperFlow and Harol) were used to generate 3 different gas flow/FIO2 combinations (80 L/min-FIO2 0.6, 100 L/min-FIO2 0.5, 120 L/min-FIO2 0.4). Different combinations of filters were applied at the flow generator input line and/or at the helmet inlet port. Two types of filters were used for this purpose: a heat and moisture exchanger filter and an electrostatic filter. The setup without filters was used as baseline. Gas flow and FIO2 were measured for each setup. RESULTS: Compared to baseline, the interposition of filters reduced the gas flow between 1-13% (P < .001). The application of a filter at the Venturi system or at the helmet generated a comparable flow reduction (-3 ± 2% vs -4 ± 2%, P = .12), whereas a greater flow reduction (-7 ± 4%) was observed when filters were applied at both sites (P < .001). An increase in FIO2 up to 5% was observed with filters applied. A strong inverse linear relationship (P < .001) was observed between the resulting gas flow and FIO2 . CONCLUSIONS: The use of filters during helmet CPAP reduced the flow delivered to the helmet and, consequently, modified FIO2 . If filters are applied, an adequate gas flow should be administered to guarantee a constant CPAP during the entire respiratory cycle and avoid rebreathing. Moreover, it might be important to measure the effective FIO2 delivered to the patient to guarantee a precise assessment of oxygenation.

Ultrasound-guided peripheral intravenous catheters insertion in patient with difficult vascular access: Short axis/out-of-plane versus long axis/in-plane, a randomized controlled trial.

PURPOSE: The aim of this study was to evaluate the rate of successful peripheral cannulation between short-axis and long-axis ultrasound guided techniques. METHODS: A single-center, two-arm randomized controlled, intention-to-treat, open-label study was conducted at the Emergency Department, between August and November 2020. Patients requiring a peripheral intravenous catheter insertion and identified as having a difficult intravascular access, were enrolled and followed for up to 96 h.The primary endpoint was the correct placement of the peripheral intravenous catheter. The secondary endpoints were number of venipunctures, intra-procedural pain, local complications, and positive blood return during the follow up. RESULTS: A total of 283 patients were enrolled: 141 subjects were randomized to the short-axis and 142 to the long-axis group. Success rate was 96.45% (135/141; 95% CI, 91.92%-98.84%) in the short-axis group compared with 92.25% (132/142; 95% CI, 86.56%-96.07%) in the long-axis group (p = 0.126). No significant differences were found in terms of intraprocedural pain and local complications. Higher rate of positive blood return at 72 h [3/17 long-axis, 14/17 short-axis (p = 0.005)] and 96 h [1/10 long-axis, 9/10 short-axis 96 h, (p = 0.022)] was found for the short-axis group. CONCLUSIONS: No differences were found between short-axis and long-axis techniques in terms of success rate, intraprocedural pain, and local complications. Despite this, a slightly higher success rate, a lower number of venipunctures, and a higher rate of positive blood return at 72 and 96 h together with an easier ultrasound technique could suggest a short-axis approach.