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Crit Care. 2015 Jan 13;19:9. doi: 10.1186/s13054-014-0726-3.

Adjusting tidal volume to stress index in an open lung condition optimizes ventilation and prevents overdistension in an experimental model of lung injury and reduced chest wall compliance.

Author information

1
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. cafeoranestesia@gmail.com.
2
Section of Anesthesiology and Critical Care, Uppsala University Hospital Uppsala, Uppsala, Sweden. fsuarezsipmann@gmail.com.
3
CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain. fsuarezsipmann@gmail.com.
4
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. andreguti@hotmail.com.
5
Department of Anesthesiology, Hospital Privado de Comunidad, Mar de Plata, Argentina. gtusman@hotmail.com.
6
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. joseacarbonell19@hotmail.com.
7
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. marisagarciap@gmail.com.
8
Clinical Research Foundation, Hospital Clínico Universitario of Valencia, Valencia, Spain. lpiqueras70@hotmail.com.
9
Pathological Anatomy Department, Hospital Clínico Universitario of Valencia, Valencia, Spain. company_amp@gva.es.
10
Radiology Department, Hospital Clinico Universitario of Valencia, Valencia, Spain. susaniefc@gmail.com.
11
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. soromarina@gmail.com.
12
Clinical Research Foundation, Hospital Clínico Universitario of Valencia, Valencia, Spain. allombart@incliva.es.
13
Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain. fco.javier.belda@uv.es.

Abstract

INTRODUCTION:

The stress index (SI), a parameter derived from the shape of the pressure-time curve, can identify injurious mechanical ventilation. We tested the hypothesis that adjusting tidal volume (VT) to a non-injurious SI in an open lung condition avoids hypoventilation while preventing overdistension in an experimental model of combined lung injury and low chest-wall compliance (Ccw).

METHODS:

Lung injury was induced by repeated lung lavages using warm saline solution, and Ccw was reduced by controlled intra-abdominal air-insufflation in 22 anesthetized, paralyzed and mechanically ventilated pigs. After injury animals were recruited and submitted to a positive end-expiratory pressure (PEEP) titration trial to find the PEEP level resulting in maximum compliance. During a subsequent four hours of mechanical ventilation, VT was adjusted to keep a plateau pressure (Pplat) of 30 cmH2O (Pplat-group, n = 11) or to a SI between 0.95 and 1.05 (SI-group, n = 11). Respiratory rate was adjusted to maintain a 'normal' PaCO2 (35 to 65 mmHg). SI, lung mechanics, arterial-blood gases haemodynamics pro-inflammatory cytokines and histopathology were analyzed. In addition Computed Tomography (CT) data were acquired at end expiration and end inspiration in six animals.

RESULTS:

PaCO2 was significantly higher in the Pplat-group (82 versus 53 mmHg, P = 0.01), with a resulting lower pH (7.19 versus 7.34, P = 0.01). We observed significant differences in VT (7.3 versus 5.4 mlKg(-1), P = 0.002) and Pplat values (30 versus 35 cmH2O, P = 0.001) between the Pplat-group and SI-group respectively. SI (1.03 versus 0.99, P = 0.42) and end-inspiratory transpulmonary pressure (PTP) (17 versus 18 cmH2O, P = 0.42) were similar in the Pplat- and SI-groups respectively, without differences in overinflated lung areas at end- inspiration in both groups. Cytokines and histopathology showed no differences.

CONCLUSIONS:

Setting tidal volume to a non-injurious stress index in an open lung condition improves alveolar ventilation and prevents overdistension without increasing lung injury. This is in comparison with limited Pplat protective ventilation in a model of lung injury with low chest-wall compliance.

PMID:
25583125
PMCID:
PMC4352239
DOI:
10.1186/s13054-014-0726-3
[Indexed for MEDLINE]
Free PMC Article

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