Sophie Perinel-Ragey1,2, Loredana Baboi1, Claude Guérin3,2,4. 1. Réanimation Médicale, Hôpital de la Croix Rousse, Lyon, France. 2. Université de Lyon, Lyon, France. 3. Réanimation Médicale, Hôpital de la Croix Rousse, Lyon, France. claude.guerin@chu-lyon.fr. 4. IMRB INSERM 955, Créteil, France.
Abstract
BACKGROUND: Limiting tidal volume (VT) in patients with ARDS may not be achieved once patient-triggered breaths occur. Furthermore, ICU ventilators offer numerous patient-triggered modes that work differently across brands. We systematically investigated, using a bench model, the effect of patient-triggered modes on the size and variability of VT at different breathing frequencies (f), patient effort, and ARDS severity. METHODS: We used a V500 Infinity ICU ventilator connected to an ASL 5000 lung model whose compliance was mimicking mild, moderate, and severe ARDS. Thirteen patient-triggered modes were tested, falling into 3 categories, namely volume control ventilation with mandatory minute ventilation; pressure control ventilation, including airway pressure release ventilation (APRV); and pressure support ventilation. Two levels of f and effort were tested for each ARDS severity in each mode. Median (first-third quartiles) VT was compared across modes using non-parametric tests. The probability of VT > 6 mL/kg ideal body weight was assessed by binomial regression and expressed as the odds ratio (OR) with 95% CI. VT variability was measured from the coefficient of variation. RESULTS: VT distribution over all f, effort, and ARDS categories significantly differed across modes (P < .001, Kruskal-Wallis test). VT was significantly greater with pressure support (OR 420 mL, 95% CI 332-527 mL) than with any other mode except for variable pressure support level. Risk for VT to be > 6 mL/kg was significantly increased with spontaneous breaths patient-triggered by pressure support (OR 19.36, 95% CI 12.37-30.65) and significantly reduced in APRV (OR 0.44, 95% CI 0.26-0.72) and pressure support with guaranteed volume mode. The risk increased with increasing effort and decreasing f. Coefficient of variation of VT was greater for low f and volume control-mandatory minute ventilation and pressure control modes. APRV had the greatest within-mode variability. CONCLUSIONS: Risk of VT > 6 mL/kg was significantly reduced in APRV and pressure support with guaranteed volume mode. APRV had the highest variability. Pressure support with guaranteed volume could be tested in patients with ARDS.
BACKGROUND: Limiting tidal volume (VT) in patients with ARDS may not be achieved once patient-triggered breaths occur. Furthermore, ICU ventilators offer numerous patient-triggered modes that work differently across brands. We systematically investigated, using a bench model, the effect of patient-triggered modes on the size and variability of VT at different breathing frequencies (f), patient effort, and ARDS severity. METHODS: We used a V500 Infinity ICU ventilator connected to an ASL 5000 lung model whose compliance was mimicking mild, moderate, and severe ARDS. Thirteen patient-triggered modes were tested, falling into 3 categories, namely volume control ventilation with mandatory minute ventilation; pressure control ventilation, including airway pressure release ventilation (APRV); and pressure support ventilation. Two levels of f and effort were tested for each ARDS severity in each mode. Median (first-third quartiles) VT was compared across modes using non-parametric tests. The probability of VT > 6 mL/kg ideal body weight was assessed by binomial regression and expressed as the odds ratio (OR) with 95% CI. VT variability was measured from the coefficient of variation. RESULTS:VT distribution over all f, effort, and ARDS categories significantly differed across modes (P < .001, Kruskal-Wallis test). VT was significantly greater with pressure support (OR 420 mL, 95% CI 332-527 mL) than with any other mode except for variable pressure support level. Risk for VT to be > 6 mL/kg was significantly increased with spontaneous breaths patient-triggered by pressure support (OR 19.36, 95% CI 12.37-30.65) and significantly reduced in APRV (OR 0.44, 95% CI 0.26-0.72) and pressure support with guaranteed volume mode. The risk increased with increasing effort and decreasing f. Coefficient of variation of VT was greater for low f and volume control-mandatory minute ventilation and pressure control modes. APRV had the greatest within-mode variability. CONCLUSIONS: Risk of VT > 6 mL/kg was significantly reduced in APRV and pressure support with guaranteed volume mode. APRV had the highest variability. Pressure support with guaranteed volume could be tested in patients with ARDS.
Authors: Eliotte L Hirshberg; Michael J Lanspa; Juhee Peterson; Lori Carpenter; Emily L Wilson; Samuel M Brown; Nathan C Dean; James Orme; Colin K Grissom Journal: Crit Care Med Date: 2018-12 Impact factor: 7.598