Tidal volume is a major determinant of cyclic recruitment-derecruitment in acute respiratory distress syndrome
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Date
2011
Journal Title
Journal ISSN
Volume Title
Publisher
EDIZIONI MINERVA MEDICA
Abstract
Background. Overdistension and cyclic recruitment-derecruitment contribute to ventilator-induced lung injury. High tidal volumes are thought to increase mortality mainly by inducing overdistension. However, experimental evidence suggests that tidal volume (VT) may also influence cyclic recruitment-derecruitment. Our main goal was to determine whether high tidal volumes increase cyclic recruitment-derecruitment in acute respiratory distress syndrome (ARDS) patients, as measured by dynamic computed tomography (CT).
Methods. We studied 9 ARDS patients with diffuse attenuations on CT who underwent a protocol including 2 ventilatory modes: (a) VT 6 mL/kg, respiratory rate 30/min, PEEP 9 cmH(2)O, (b) VT 12 mL/kg, respiratory rate 15/min, PEEP 9 cmH(2)O. A dynamic computed tomography of 8 seconds on a fixed transverse region was performed during each ventilator mode. Cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration and was expressed as % of lung tissue weight.
Results. VT 12 mL/kg exhibited less non-aerated tissue at expiration compared to VT 6 ml/kg (40.15 [35.94-56.00] and 45.31 [37.95-59.32], respectively, P<0.05). However, VT 12 ml/kg increased cyclic recruitment-derecruitment compared to VT 6 mL/kg (7.32 [6.58-9.29] mL/kg vs. 4.51 [3.42-5.75] mL/kg, P<0.01). Tidal hyperinflation was also larger at VT 12 mL/kg (0.55 [0.27-2.24] vs. 0.24 [0.18-0.83], P<0.01).
Conclusion. High tidal volume is a major determinant of cyclic recruitment-derecruitment in ARDS patients with diffuse attenuations. (Minerva Anestesiol 2011;77:418-26)
Methods. We studied 9 ARDS patients with diffuse attenuations on CT who underwent a protocol including 2 ventilatory modes: (a) VT 6 mL/kg, respiratory rate 30/min, PEEP 9 cmH(2)O, (b) VT 12 mL/kg, respiratory rate 15/min, PEEP 9 cmH(2)O. A dynamic computed tomography of 8 seconds on a fixed transverse region was performed during each ventilator mode. Cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration and was expressed as % of lung tissue weight.
Results. VT 12 mL/kg exhibited less non-aerated tissue at expiration compared to VT 6 ml/kg (40.15 [35.94-56.00] and 45.31 [37.95-59.32], respectively, P<0.05). However, VT 12 ml/kg increased cyclic recruitment-derecruitment compared to VT 6 mL/kg (7.32 [6.58-9.29] mL/kg vs. 4.51 [3.42-5.75] mL/kg, P<0.01). Tidal hyperinflation was also larger at VT 12 mL/kg (0.55 [0.27-2.24] vs. 0.24 [0.18-0.83], P<0.01).
Conclusion. High tidal volume is a major determinant of cyclic recruitment-derecruitment in ARDS patients with diffuse attenuations. (Minerva Anestesiol 2011;77:418-26)
Description
Keywords
Ventilator-induced lung injury, Respiratory distress syndrome, adult, Tomography, X-ray computed, Ventilation, mechanical, ACUTE LUNG INJURY, END-EXPIRATORY PRESSURE, TRANSPULMONARY PRESSURE, MECHANICAL VENTILATION, REGIONAL-DISTRIBUTION, DYNAMIC CT, COLLAPSE, TIME, DISTRIBUTIONS, METAANALYSIS