Impact of Chest Wall Modifications and Lung Injury on the Correspondence Between Airway and Transpulmonary Driving Pressures. Issue 8 (August 2015)

• Record Type: Journal Article
• Authors: Cortes-Puentes, Gustavo A.; Keenan, Joseph C.; Adams, Alexander B.; Parker, Emily D.; Dries, David J.; Marini, John J.
• Is Part Of: Critical care medicine. Volume 43:Issue 8(2015)
• Publication Date: 2015-08
• Subjects: airway driving pressure -- intra-abdominal hypertension -- lung injury -- peep -- transpulmonary pressure -- ventilator-induced lung injury; Critical care medicine -- Periodicals; Soins intensifs -- Périodiques; 616.028
• DOI: 10.1097/CCM.0000000000001036
• Languages: English
• ISSNs: 0090-3493

Abstract

Abstract : Objective: Recent interest has arisen in airway driving pressure (DPAW ), the quotient of tidal volume ( V T ), and respiratory system compliance ( C RS ), which could serve as a direct and easily measured marker for ventilator-induced lung injury risk. We aimed to test the correspondence between DPAW and transpulmonary driving pressure (DPTP )—the quotient of VT and lung compliance (CL ), in response to intra-abdominal hypertension and changes in positive end-expiratory pressure during different models of lung pathology. Design: Well-controlled experimental setting that allowed reversible modification of chest wall compliance (CCW ) in a variety of models of lung pathology. Setting: Large animal laboratory of a university-affiliated hospital. Subjects: Ten deeply anesthetized swine. Interventions: Application of intra-abdominal pressures of 0 and 20 cm H2 O at positive end-expiratory pressure of 1 and 10 cm H2 O, under volume-controlled mechanical ventilation in the settings of normal lungs (baseline), unilateral whole-lung atelectasis, and unilateral and bilateral lung injuries caused by saline lavage. Measurements and Main Results: Pulmonary mechanics including esophageal pressure and calculations of DPAW, DPTP, C RS, C L, and C CW . When compared with normal intra-abdominal pressures, intra-abdominal hypertension increased DPAW, during both "normal lung conditions" ( p < 0.0001) and "unilateral atelectasis" ( p = 0.0026). In contrast, DPTP remained virtually unaffected by changes in positive end-expiratory pressure or intra-abdominal pressures in both conditions. During unilateral lung injury, both DPAW and DPTP were increased by the presence of intra-abdominal hypertension ( p < 0.0001 and p = 0.0222, respectively). During bilateral lung injury, intra-abdominal hypertension increased both DPAW (at positive end-expiratory pressure of 1 cm H2 O, p < 0.0001; and at positive end-expiratory pressure of 10 cm H2 O, p = 0.0091) and DPTP (at positive end-expiratory pressure of 1 cm H2 O, p = 0.0510; and at positive end-expiratory pressure of 10 cm H2 O, p = 0.0335). Conclusions: Our data indicate that DPAW is influenced by reductions in chest wall compliance and by underlying lung properties. As with other measures of pulmonary mechanics that are based on unmodified P AW, caution is advised in attempting to attribute hazard or safety to any specific absolute value of DPAW .