The transpulmonary pressure as an indicator of lung stress in the disorder of chest wall mechanics in pediatric acute lung injury: Study in pig model

Objectives: To determine the role of the endinspiratory transpulmonary pressure as an indicator of the lung stress in the disorder of chest wall mechanics, in pig model. Design: Experimental study. Setting: Department of Surgery and Radiology, Veterinary Medicine, Bogor Agricultural Institute. Subjects: Nine healthy mixed breed domestic piglets were divided into 2 groups: intervention/ splinted chest wall (n=5) and control (n=4). Intervention: This study had approval from Animal Care and Use Committee. The care and handling animal were accorded with National Institute of Health guideline. All of animals were anesthetized, muscle paralyzed and bronchial lavage with warm saline, in supine position. Both group were mechanically ventilated and underwent lung recruitment using incremental-decremental technique. Chest wall splinting was conducted in intervention group while the control group did not. Measurement and Main Results: Transpulmonary pressures calculated after measure the eso-. phageal pressure using esophageal catheters. The transpulmonary pressure in intervention group prior to (1.80±2.28 cmH2O) and after (11.00±5.83 cmH2O) recruitment maneuver, increased significantly compared with control group prior to (1.25±3.68 cmH2O) and after (3.25±1.18 cmH2O), with p value 0.04. The difference of mean end-inspiratory transpulmonary pressure (Ptp plateau) between intervention and control group was significant (p=0.05). ΔPtp plateau values have strong correlation with the increasing of chest wall elastance (Ecw) in the intervention group (p=0.001, R²=0.8) and control group (p=0.007, r=0.7), as well as the correlation of ΔPtp plateau with decreasing the lung compliance (Cl) (p=0.05, r=0.8). The strong correlation between ΔPtp plateau and ΔPaw (p=0.001, r=0.7) in the intervention group showed the potency of the transpulmonary pressure to reflect the real lung distending pressure and the lung stress. Conclusions: The measurement of end-inspiratory transpulmonary pressure is reliable as an indicator of lung stress in disorder of chest wall mechanics.