Ventilator gas delivery wave form substantially impacts plateau pressure and peak-to-plateau pressure gradient determination. Issue 5 (May 2015)

• Record Type: Journal Article
• Authors: Maung, Adrian Anthony; Johnson, Dirk C.; Luckianow, Gina M.; Kaplan, Lewis J.
• Is Part Of: Journal of trauma and acute care surgery. Volume 78:Issue 5(2015:May)
• Publication Date: 2015-05
• Subjects: Surgical intensive care -- Periodicals; Surgical emergencies -- Periodicals; Wounds and injuries -- Surgery -- Periodicals; 617.026
• DOI: 10.1097/TA.0000000000000615
• Languages: English
• ISSNs: 2163-0755

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>BACKGROUND</title> <p>To determine whether plateau pressure (Pplat) measurement is lowered and peak airway pressure (Pawpeak)–to–Plat gradient is increased by measurement on a decelerating compared with square gas delivery wave form.</p> </sec> <sec> <title>METHODS</title> <p>Prospective before and after study of mechanically ventilated injured and critically ill patients in an adult surgical intensive care unit. Pplat, Pawpeak, and Pawpeak-to-Pplat gradient were measured on decelerating and square gas delivery wave forms.</p> </sec> <sec> <title>RESULTS</title> <p>Pplat and other routine ventilator parameters were measured in 82 (47 trauma, 35 emergency general surgery) consecutive convenience sampled adult intensive care unit patients on decelerating and then square gas delivery wave forms. Peak gas flow was fixed at 40 L/min; all other parameters (rate, tidal volume, positive end-expiratory pressure) were held constant. All patients were managed on assist control volume cycled ventilation using fentanyl and midazolam or propofol; no neuromuscular blockade was used. Patients with Pawpeak more than 35 cm H<sub>2</sub>O were excluded. Comparing decelerating with square gas delivery, mean Pawpeak was lower (25.1 ± 2.3 cm H<sub>2</sub>O vs. 33.1 ± 2.1 cm H<sub>2</sub>O; <italic>p</italic> < 0.0001) and mean Pplat was lower (21.3 ± 1.9 cm H<sub>2</sub>O vs. 24.8 ± 2.5 cm H<sub>2</sub>O; <italic>p</italic> < 0.0001), resulting in a decreased Pawpeak-to-Pplat gradient (3.8 ± 2.1 vs. 8.3 ± 2.3; <italic>p</italic> < 0.0001).</p> </sec> <sec> <title>CONCLUSION</title> <p>Changing from a decelerating to a square gas delivery wave form significantly increases Pplat and Pawpeak, thereby increasing the Pawpeak-to-Pplat gradient. This increase may prompt unwarranted therapy aimed at reducing the gradient to its normal value of 4 cm H<sub>2</sub>O pressure or less. Conversely, patients with a high Pawpeak on a square wave form may benefit from transitioning to a decelerating wave form before changing ventilation parameters.</p> </sec> <sec> <title>LEVEL OF EVIDENCE</title> <p>Diagnostic study, level III.</p> </sec> </abstract>