by Fabia Diniz-Silva, Henrique T. Moriya, Adriano M.
Alencar, Marcelo B. P. Amato, Carlos R. R. Carvalho and Juliana C. Ferreira
Annals of Intensive Care volume 10,
Article number: 18 (2020)
Background
Protective mechanical ventilation is recommended for
patients with acute respiratory distress syndrome (ARDS), but it usually
requires controlled ventilation and sedation. Using neurally adjusted
ventilatory assist (NAVA) or pressure support ventilation (PSV) could have
additional benefits, including the use of lower sedative doses, improved
patient–ventilator interaction and shortened duration of mechanical
ventilation. We designed a pilot study to assess the feasibility of keeping
tidal volume (VT) at protective levels with NAVA and PSV in patients with ARDS.
Methods
We conducted a prospective randomized crossover trial in
five ICUs from a university hospital in Brazil and included patients with ARDS
transitioning from controlled ventilation to partial ventilatory support. NAVA
and PSV were applied in random order, for 15 min each, followed by
3 h in NAVA. Flow, peak airway pressure (Paw) and electrical activity of
the diaphragm (EAdi) were captured from the ventilator, and a software (Matlab,
Mathworks, USA), automatically detected inspiratory efforts and calculated
respiratory rate (RR) and VT. Asynchrony events detection was based on
waveform analysis.
Results
We randomized 20 patients, but the protocol was interrupted
for five (25%) patients for whom we were unable to maintain VT below
6.5 mL/kg in PSV due to strong inspiratory efforts and for one patient for
whom we could not detect EAdi signal. For the 14 patients who completed the
protocol, VT was 5.8 ± 1.1 mL/kg for NAVA and
5.6 ± 1.0 mL/kg for PSV (p = 0.455) and there were no
differences in RR (24 ± 7 for NAVA and 23 ± 7 for
PSV, p = 0.661). Paw was greater in NAVA (21 ± 3 cmH2O)
than in PSV (19 ± 3 cmH2O, p = 0.001). Most patients
were under continuous sedation during the study. NAVA reduced triggering delay
compared to PSV (p = 0.020) and the median asynchrony Index was 0.7%
(0–2.7) in PSV and 0% (0–2.2) in NAVA (p = 0.6835).
Conclusions
It was feasible to keep VT in protective levels
with NAVA and PSV for 75% of the patients. NAVA resulted in similar VT, RR
and Paw compared to PSV. Our findings suggest that partial ventilatory
assistance with NAVA and PSV is feasible as a protective ventilation strategy
in selected ARDS patients under continuous sedation.
Trial registration ClinicalTrials.gov (NCT01519258).
Registered 26 January 2012, https://clinicaltrials.gov/ct2/show/NCT01519258
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