Neural versus pneumatic control of pressure support in patients with chronic obstructive pulmonary diseases at different levels of positive end expiratory pressure: a physiological study

Abstract

IntroductionIntrinsic positive end-expiratory pressure (PEEPi) is a “threshold” load that must be overcome to trigger conventional pneumatically-controlled pressure support (PSP) in chronic obstructive pulmonary disease (COPD). Application of extrinsic PEEP (PEEPe) reduces trigger delays and mechanical inspiratory efforts. Using the diaphragm electrical activity (EAdi), neurally controlled pressure support (PSN) could hypothetically eliminate asynchrony and reduce mechanical inspiratory effort, hence substituting the need for PEEPe. The primary objective of this study was to show that PSN can reduce the need for PEEPe to improve patient-ventilator interaction and to reduce both the “pre-trigger” and “total inspiratory” neural and mechanical efforts in COPD patients with PEEPi. A secondary objective was to evaluate the impact of applying PSN on breathing pattern.MethodsTwelve intubated and mechanically ventilated COPD patients with PEEPi ≥ 5 cm H2O underwent comparisons of PSP and PSN at different levels of PEEPe (at 0 %, 40 %, 80 %, and 120 % of static PEEPi, for 12 minutes at each level on average), at matching peak airway pressure. We measured flow, airway pressure, esophageal pressure, and EAdi, and analyzed neural and mechanical efforts for triggering and total inspiration. Patient-ventilator interaction was analyzed with the NeuroSync index.ResultsMean airway pressure and PEEPe were comparable for PSP and PSN at same target levels. During PSP, the NeuroSync index was 29 % at zero PEEPe and improved to 21 % at optimal PEEPe (P < 0.05). During PSN, the NeuroSync index was lower (<7 %, P < 0.05) regardless of PEEPe. Both pre-trigger (P < 0.05) and total inspiratory mechanical efforts (P < 0.05) were consistently higher during PSP compared to PSN at same PEEPe. The change in total mechanical efforts between PSP at PEEPe0% and PSN at PEEPe0% was not different from the change between PSP at PEEPe0% and PSP at PEEPe80%.ConclusionPSN abolishes the need for PEEPe in COPD patients, improves patient-ventilator interaction, and reduces the inspiratory mechanical effort to breathe.Trial registrationClinicaltrials.gov NCT02114567. Registered 04 November 2013.

A diaphragmatic electrical activity-based optimization strategy during pressure support ventilation improves synchronization but does not impact work of breathing

“…Eadi-triggered and -cycled assisted pressure ventilation (or PSV N ) reduces T d in comparison with both standard PSV and Eadi-optimized PSV mode using pneumatic signal. These results are consistent with previous studies performed in standard NAVA mode [ 17 , 22 , 30 ] or in PSV N mode during invasive ventilation [ 31 ] or during helmet-delivered noninvasive ventilation [ 32 , 33 ] and were expected, as an Eadi increase is detected earlier by the ventilator than flow or pressure changes [ 34 ] related to air motion in the lungs. Interestingly, the very short T d observed in PSV N (<50 ms) is lower than the conscious threshold of perception (about 150 ms) [ 35 ], which may contribute to optimize patient comfort.…”

“…Interestingly, the very short T d observed in PSV N (<50 ms) is lower than the conscious threshold of perception (about 150 ms) [ 35 ], which may contribute to optimize patient comfort. In our study, as in Liu et al data [ 31 ], PSV N allows improving T iex in comparison with standard and Eadi-optimized PSV mode.…”

New setting of neurally adjusted ventilatory assist for noninvasive ventilation by facial mask: a physiologic study

“…Consistent with the results of these investigations, in the present study PS N outperforms PS P with respect to PTP 300-index and PTP 500-index , PTPt [4, 16, 30], Delay TR-insp , Time synch /TI neu and AI [4, 16, 30], and comfort [4, 30]. In accordance with Cammarota et al [4], who compared the same three modes delivering NIV by helmet, PS N improved pressurization PTP 300-index and PTP 500-index , and comfort with respect to both PS P and NAVA, while in contrast to that study, PS N neither increased PTP 200 , compared to PS P , nor reduced EAdi, compared to both PS P and NAVA.…”

“…PS N consists of increasing the user-controlled gain factor (NAVA level) at the maximum level, while limiting peak airway pressure (Paw peak ) by adjusting the upper pressure limit [4, 16]. …”

Neurally-Adjusted Ventilatory Assist Versus Noninvasive Pressure Support Ventilation in COPD Exacerbation: The NAVA-NICE Trial

“…9,23 Several studies have described use of NAVA in subjects with COPD exacerbation. 11,14,[29][30][31][32][33] Among these, few studies have used NAVA while subjects were receiving either mechanical ventilation 29,30 or venovenous extracorporeal membrane oxygenation, 31 and reported the effects of NAVA on patient-ventilator interactions. However, other studies have compared NIV-NAVA to NIV-PSV in various patient populations.…”