Abstract.
Objective: In acute lung injury (ALI) mechanical ventilation damages lungs. We hypothesised that aspiration and replacement of dead space during expiration (ASPIDS) allows normocapnic ventilation at higher end-expiratory pressure (PEEP) and reduced tidal volume (VT), peak and plateau pressures (Pawpeak, Pawplat), thus avoiding lung damage. Setting: University Hospital. Patients: Seven consecutive sedated and paralysed ALI patients were studied. Interventions and measurements: Single breath test for CO2 and multiple elastic pressure volume (Pel/V) curves recorded from different end-expiratory pressures guided ventilatory setting at ASPIDS. ASPIDS was studied at respiratory rate (RR) of 14 min–1 and then 20 min–1 with minute ventilation maintaining stable CO2 elimination. Results: Alveolar and airway dead spaces were 24.3% and 31.3% of VT, respectively. Multiple Pel/V curves showed a shift towards lower volume at decreasing PEEP, thus indicating that patients required a higher PEEP. At ASPIDS, PEEP was increased from 8.9 cmH2O to 12.6 cmH2O and VT reduced from 11 ml/kg to 8.9 ml/kg at RR 14 min–1 and to 6.9 ml/kg at RR 20 min–1. A significant decrease in Pawpeak (36.7 vs 32 at RR 14 min–1 and 28.7 at RR 20 min–1) and Pawplat (29.9 vs 27.3 at RR 14 min–1 and 24.1 at RR 20 min–1) were observed. PaCO2 remained stable. No intrinsic PEEP developed. No side effects were noticed. Conclusions: ASPIDS allowed the use of higher PEEP at lower VT and inflation pressure and constant PaCO2. Multiple Pel/V curves gave insight into the tendency of lungs to collapse.
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Final revision received: 30 May 2001
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De Robertis, E., Servillo, G., Tufano, R. et al. Aspiration of dead space allows isocapnic low tidal volume ventilation in acute lung injury. Relationships to gas exchange and mechanics. Intensive Care Med 27, 1496–1503 (2001). https://doi.org/10.1007/s001340101046
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DOI: https://doi.org/10.1007/s001340101046