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BACKGROUND: This study assessed the effects of a new interface that combined CPAP 10 cm H2O by using a helmet with high-flow nasal cannula (HFNC) at varying flows in healthy volunteers. Outcome measures included pharyngeal pressures, diaphragm kinetics, breathing frequency, the temperature inside the helmet, and comfort. METHODS: After baseline assessment during spontaneous breathing, HFNC was applied at flows of 30, 40, and 50 L/min. Successively, the volunteers underwent helmet CPAP at 10 cm H2O and CPAP + HFNC at flows of 30, 40, and 50 L/min. We measured the variations of pharyngeal pressures at end-expiration and end-inspiration, referenced to spontaneous breathing for HFNC and to CPAP for CPAP + HFNC, diaphragm displacement and thickness at end-expiration and thickness at end-inspiration, breathing frequency, the temperature inside the helmet, the occurrence of the fog effect, and comfort. RESULTS: Variations of pharyngeal pressures at end-inspiration changes were small overall and clinically unimportant. With the mouth closed, at increasing HFNC flow, variations of pharyngeal pressures at endexpiration increased during both HFNC (from 2.8 up to 7.7) and, to a lesser extent, CPAP + HFNC (from 2.7 up to 3.8) (P < .001 for all comparisons). These variations were attenuated during open-mouth breathing. HFNC > 40 L/min and CPAP + HFNC ≥ 40 L/min compared with spontaneous breathing and CPAP, respectively, increased diaphragm displacement (P = .001), thickness at end-inspiration and thickness at end-expiration (P < .003 for both). At all flows, breathing frequency was slightly, although significantly, lower with CPAP + HFNC than with HFNC alone (P < .003). The temperature inside the helmet increased slightly and insignificantly at flows of ≤40 L/min with CPAP + HFNC compared with CPAP alone. The fog effect never occurred, whereas comfort was always rated as optimal, without differences between trials. CONCLUSIONS: CPAP + HFNC was well tolerated, with no adverse effects. Based on our findings, there was no need to vary the CPAP level when adding HFNC. At least in healthy subjects, CPAP + HFNC at 30 L/min seemed to be the best combination. [ABSTRACT FROM AUTHOR]

Background: Veno-venous extracorporeal membrane oxygenation (V-V ECMO) is a rapidly expanding life-support technique worldwide. The most common indications are severe hypoxemia and/or hypercapnia, unresponsive to conventional treatments, primarily in cases of acute respiratory distress syndrome. Concerning potential contraindications, there is no mention of microbiological history, especially related to multi-drug resistant (MDR) bacteria isolated before V-V ECMO placement. Our study aims to investigate: (i) the prevalence and incidence of MDR Gram-negative (GN) bacteria in a cohort of V-V ECMOs; (ii) the risk of 1-year mortality, especially in the case of predetected MDR GN bacteria; and (iii) the impact of annual hospital V-V ECMO volume on the probability of acquiring MDR GN bacteria., Methods: All consecutive adults admitted to the Intensive Care Units of 5 Italian university-affiliated hospitals and requiring V-V ECMO were screened. Exclusion criteria were age < 18 years, pregnancy, veno-arterial or mixed ECMO-configuration, incomplete records, survival < 24 h after V-V ECMO. A standard protocol of microbiological surveillance was applied and MDR profiles were identified using in vitro susceptibility tests. Cox-proportional hazards models were applied for investigating mortality., Results: Two hundred and seventy-nine V-V ECMO patients (72% male) were enrolled. The overall MDR GN bacteria percentage was 50%: 21% (n.59) detected before and 29% (n.80) after V-V ECMO placement. The overall 1-year mortality was 42%, with a higher risk observed in predetected patients (aHR 2.14 [1.33-3.47], p value 0.002), while not in 'V-V ECMO-acquired MDR GN bacteria' group (aHR 1.51 [0.94-2.42], p value 0.090), as compared to 'non-MDR GN bacteria' group (reference). Same findings were found considering only infections. A larger annual hospital V-V ECMO volume was associated with a lower probability of acquiring MDR GN bacteria during V-V ECMO course (aOR 0.91 [0.86-0.97], p value 0.002)., Conclusions: 21% of MDR GN bacteria were detected before; while 29% after V-V ECMO connection. A history of MDR GN bacteria, isolated before V-V ECMO, was an independent risk factor for mortality. The annual hospital V-V ECMO volume affected the probability of acquiring MDR GN bacteria. Trial Registration ClinicalTrial.gov Registration Number NCTNCT06199141, date 12.26.2023., (© 2024. The Author(s).)