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Purpose: Standard polyvinylchloride (PVC) endotracheal tube (ETT) cuffs do not protect from aspiration across the cuff, a leading cause of ventilator-associated pneumonia (VAP). In a long-lasting in vitro study we compared the effect of different cuff materials (PVC, polyurethane, and guayule latex), shapes (cylindrical, conical), and positive end expiratory pressures (PEEP) in reducing fluid leakage across the cuff. Methods: We compared fluid leakage across a cylindrical double-layer guayule latex prototype cuff, three cylindrical PVC cuffs (Mallinckrodt Hi-Lo, Mallinckrodt HighContour, Portex Ivory), one conical PVC cuff (Mallinckrodt TaperGuard), and two polyurethane cuffs (Mallinckrodt SealGuard, conical; Microcuff, cylindrical). Ten centimeters of dyed water was poured above the cuffs inflated (pressure 30 cmH 2O) in a vertical cylinder (diameter 20 mm). A respiratory circuit connected the bottom of the cylinder to a breathing bag inflated at four pressures (PEEP = 0, 5, 10, 15 cmH2O). Pictures were taken every 60 s for 24 h to measure leakage as a reduction in the water column above the cuff. Five new ETTs of each type were tested. Results: The guayule latex cuffs showed no leakage at all the PEEP levels. Both the cylindrical and conical polyurethane cuffs showed limited leakage (2.1 ± 1.8 cm of water) only for PEEP zero. The PVC cuffs showed reduced leakage with increasing PEEP: 8.4 ± 1.5, 7.8 ± 2.2, 2.2 ± 1.0, and 0 cm of water at 0, 5, 10, and 15 cmH2O, respectively. Among all the PVC cuffs, the conical shape ensured higher sealing properties. Conclusions: The guayule latex cuffs always prevented fluid leakage; the polyurethane and PVC cuffs required incremental levels of PEEP to prevent fluid leakage ever-present at zero PEEP. © Copyright jointly held by Springer and ESICM 2010.

Purpose: We investigated the effects of periodical high pressure breaths (SIGH) or biphasic positive pressure ventilation (BIPAP) during helmet continuous positive airway pressure (CPAP) in patients with acute hypoxic respiratory failure. Methods: We used a recently developed electromechanical expiratory valve (TwinPAP®, StarMed, Mirandola, Italy), which is time-cycled between two customizable positive end-expiratory pressure (PEEP) levels. We studied 21 patients (67 ± 17 years old) undergoing helmet CPAP. Continuous flow CPAP system was set at 60 l/min flow rate while maintaining clinical FiO2 (51 ± 15%). Five steps, lasting 1 h each, were applied: (1) spontaneous breathing with PEEP 0 cmH2O (SB), (2) CPAP with PEEP 8 cmH2O (CPAPbasal), (3) low PEEP, 8 cmH2O, for 25 s and high PEEP, 25 cmH2O, for 5 s (SIGH), (4) low PEEP, 8 cmH2O, for 3 s and high PEEP, 20 cmH2O, for 3 s (BIPAP), (5) CPAP with PEEP 8 cmH2O (CPAPfinal). We randomized the sequence of SIGH and BIPAP. Results: PaO2 was significantly higher during all steps compared to SB. When compared to CPAP basal, both SIGH and BIPAP induced a further increase in PaO 2. PaO2 during SIGH and BIPAP were not different. The oxygenation improvement was maintained during CPAPfinal. Conclusions: Superimposed, nonsynchronized positive pressure breaths delivered during helmet CPAP by means of the TwinPAP® system may improve oxygenation in patients with acute hypoxemic respiratory failure, even at a rate as low as two breaths per minute. © 2010 jointly held by Springer and ESICM.

PURPOSE: Extracorporeal CO2 removal is an effective procedure to allow a protective ventilatory strategy in ARDS patients, but it is technically challenging due to the high blood flow required. Increasing the CO2 transfer through the membrane lung (ML) may lower the demand of extracorporeal blood flow and consequently allow for a wider clinical application of this technique. Since only the dissolved CO2 (5% of the total CO2 content) is easily removed by the ML, we tested whether acidifying the blood entering the ML to convert bicarbonate ions towards dissolved CO2 could enhance the CO2 transfer though the ML. METHODS: Six pigs were connected to an extracorporeal circuit comprising a ML. The extracorporeal blood flow was 500 ml/min, while the gas flow was 10 l/min. A 15-min continuous infusion of 0.5 N lactic acid was added to the extracorporeal blood flow before the ML at a rate of 1, 2 and 5 mEq/min. Between steps we waited for a reequilibration time of at least 30 min. RESULTS: Acid infusion at 0, 1, 2 and 5 mEq/min increased pCO2 (56.19 +/- 7.92, 68.24 +/- 11.73, 84.28 +/- 11.17 and 136.66 +/- 18.46 mmHg, respectively) and decreased pH (7.39 +/- 0.05, 7.30 +/- 0.05, 7.20 +/- 0.05 and 6.91 +/- 0.05, respectively). ML CO2 removal increased 11, 23 and 70% during acid infusion at 1, 2 and 5 mEq/min, respectively. CONCLUSIONS: Blood acidification at the inlet of a ML with infusion of 1, 2 and 5 mEq/min of lactic acid can increase the CO2 removal capacity of the ML up to 70%.

PURPOSE: Assessing feasibility and physiological effects of sedation with sevoflurane, administered with the anesthetic conserving device (AnaConDa), in comparison with propofol and remifentanil. METHODS: Seventeen patients undergoing mechanical ventilation underwent sedation with sevoflurane delivered with AnaConDa (phase SevAn), preceded and followed by sedation with propofol and remifentanil (phases ProRe(1), ProRe(2)), with the same sedation targets. RESULTS: With both strategies it was possible to achieve the sedation targets. Time required to sedate and awake patients was greater during SevAn than ProRe(1): respectively, 3.3 +/- 3.0 versus 8.9 +/- 6.1 and 7.47 +/- 5.05 versus 16.3 +/- 11.4 min. During SevAn the PaCO(2) and minute ventilation increased. Hemodynamics was stable between ProRe(1) and SevAn, except for an increase in heart rate in the SevAn phase. Environmental pollution from sevoflurane was within the safety limits. CONCLUSIONS: Sevoflurane can be effectively and safely used for short-term sedation of ICU patients with stable hemodynamic conditions.