Extubation Failure After Successful Spontaneous Breathing Trial: Prediction Is Still a Challenge!

n/

Performance of different continuous positive airway pressure helmets equipped with safety valves during failure of fresh gas supply

Purpose: We assessed the performance of different continuous positive airway pressure (CPAP) helmets equipped with a safety valve during discontinuation of fresh gas flow. Methods: This was a physiological study of five healthy volunteers. We delivered CPAP (fresh gas flow 60 l/min, FiO260%, PEEP 5 cmH2O) with three different helmets in a random sequence: 4Vent (R\uc3\ubcsch), HelmHAR-cp (Harol) and CaStar CP210 (StarMed). For each helmet we randomly applied, for up to 4 min, three disconnections of fresh gas flow: helmet inlet (Dinlet), flowmeter (Dflowmeter) and gas source (Dsource). We continuously recorded from a nostril: end-tidal CO2(PetCO2), inspiratory CO2(PiCO2), fraction of inspired oxygen (FiO2) and respiratory rate (RR). Results: During every disconnection we observed an increase in PiCO2and PetCO2with a drop in FiO2, while RR did not change. FiO2decreased more quickly in the CaStar, equipped with the largest safety valve, during Dsourceand Dflowmeter, while FiO2decreased more quickly during Dinletin CaStar and in 4Vent. PiCO2resulted in a lower increase in CaStar during Dsourceand Dflowmetercompared to 4Vent. PetCO2in CaStar increases more slowly compared to 4Vent during Dsourceand more slowly compared to the other two helmets during Dflowmeter. During Dinletsimilar degrees of CO2rebreathing and PetCO2were recorded among all the helmets. Conclusions: To minimize CO2rebreathing during disconnection of the fresh gas supply while performing helmet CPAP, it is desirable to utilize large helmets with a large anti-suffocation valve. Monitoring and alarm systems should be employed for safe application of helmet CPAP. \uc2\ua9 2011 jointly held by Springer and ESICM

Effects on membrane lung gas exchange of an intermittent high gas flow recruitment maneuver: preliminary data in veno-venous ECMO patients

Gas exchange capabilities of polymethylpentene membrane lungs (MLs) worsen over time. ML deterioration is related to protein deposit and clot formation. Condensation and trapping of water vapor inside ML hollow fibers might affect ML performances as well. Increasing sweep gas flow (GF) could remove such fluid. The purpose of this study was to evaluate the effects on ML gas exchange of a recruitment maneuver (RM) based on a brief increase in GF, during veno-venous ECMO support. Short-term (15\uc2 min) effects of 20 RMs were assessed. RM raised ML CO2 removal from 149\uc2 \uc2\ub1\uc2 37 to 174\uc2 \uc2\ub1\uc2 41\uc2 ml/min (p\uc2&nbsp

Respiratory electrodialysis a novel, highly efficient extracorporeal CO2 removal technique

Rationale: We developed an innovative, minimally invasive, highly efficient extracorporeal CO2 removal (ECCO2R) technique called respiratory electrodialysis (R-ED). Objectives: To evaluate the efficacy of R-ED in controlling ventilation compared with conventional ECCO2R technology. Methods: Five mechanically ventilated swine were connected to a custom-made circuit optimized for R-ED, consisting of a hemofilter, a membrane lung, and an electrodialysis cell. Electrodialysis regionally modulates blood electrolyte concentration to convert bicarbonate to CO2 before entering the membrane lung, enhancing membrane lung CO2 extraction. All animals underwent three repeated experimental sequences, consisting of four steps: baseline (1 h), conventionalECCO2R(2 h), R-ED (2 h), and finalNOECCO2R (1 h). Blood and gas flow were 250 ml/min and 10 L/min, respectively. Tidal volume was set at 8 ml/kg, and respiratory rate was adjusted to maintain arterial PCO2 at 50 mm Hg. Measurements and Main Results: During R-ED, chloride andH1 concentration increased in blood entering the membrane lung, almost doubling CO2 extraction compared with ECCO2R (11266 vs. 6465 ml/min, P,0.001). Compared with baseline, R-ED and ECCO2R reduced minute ventilation by 50% and 27%, respectively. Systemic arterial gas analyses remained stable during the experimental phases. No major complication occurred, but there was an increase in creatinine level. Conclusions: In this first in vivo application, we proved electrodialysis feasible and effective in increasingmembrane lung CO2 extraction. R-ED was more effective than conventional ECCO2R technology in controlling ventilation. Further studies are warranted to assess the safety profile of R-ED, especially regarding kidney function