Pressure‐decay testing of pleural air leaks in intact murine lungs: evidence for peripheral airway regulation. Issue 10 (24th May 2018)

• Record Type: Journal Article
• Authors: Servais, Andrew B.; Valenzuela, Cristian D.; Ysasi, Alexandra B.; Wagner, Willi L.; Kienzle, Arne; Loring, Stephen H.; Tsuda, Akira; Ackermann, Maximilian; Mentzer, Steven J.
• Is Part Of: Physiological reports. Volume 6:Issue 10(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-24
• Subjects: Air leak -- injury -- lung -- ventilation; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.13712
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: The critical care management of pleural air leaks can be challenging in all patients, but particularly in patients on mechanical ventilation. To investigate the effect of central airway pressure and pleural pressure on pulmonary air leaks, we studied orotracheally intubated mice with pleural injuries. We used clinically relevant variables – namely, airway pressure and pleural pressure – to investigate flow through peripheral air leaks. The model studied the pleural injuries using a pressure‐decay maneuver. The pressure‐decay maneuver involved a 3 sec ramp to 30 cmH2 0 followed by a 3 sec breath hold. After pleural injury, the pressure‐decay maneuver demonstrated a distinctive airway pressure time history. Peak inflation was followed by a rapid decrease to a lower plateau phase. The decay phase of the inflation maneuver was influenced by the injury area. The rate of pressure decline with multiple injuries (28 ± 8 cmH2 0/sec) was significantly greater than a single injury (12 ± 3 cmH2 O/sec) ( P < 0.05). In contrast, the plateau phase pressure was independent of injury surface area, but dependent upon transpulmonary pressure. The mean plateau transpulmonary pressure was 18 ± 0.7 cm H2 O. Finally, analysis of the inflation ramp demonstrated that nearly all volume loss occurred at the end of inflation ( P < 0.001). We conclude that the air flow through peripheral lung injuries was greatest at increased lung volumes and limited by peripheral airway closure. In addition to suggesting an intrinsic mechanism for limiting flow through peripheral air leaks, these findings suggest the utility of positive end‐expiratory pressure and negative pleural pressure to maintain lung volumes in patients with pleural injuries. Abstract : The authors use novel pressure‐decay testing – and clinical variables of airway pressure and pleural pressure – to demonstrate transpulmonary pressure‐dependent flow limitation in the peripheral airways. These insights provide physiological insights valuable for the ventilator management of patients with pleural air leaks.