Neurally Adjusted Ventilatory Assist (NAVA) or Pressure Support Ventilation (PSV) during spontaneous breathing trials in critically ill patients: a crossover trial

Author(s)

Ferreira, Juliana C. ^[1] ; Diniz-Silva, Fabia ^[1] ; Moriya, Henrique T. ^[2] ; Alencar, Adriano M. ^[3] ; Amato, Marcelo B. P. ^[1] ; Carvalho, Carlos R. R. ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Med, Hosp Clin HCFMUSP, Div Pneumol, Inst Coracao, Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Biomed Engn Lab, Escola Politecn, Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Inst Fis, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: BMC PULMONARY MEDICINE; v. 17, NOV 7 2017.
• Web of Science Citations: 14

Abstract

Background: Neurally Adjusted Ventilatory Assist (NAVA) is a proportional ventilatory mode that uses the electrical activity of the diaphragm (EAdi) to offer ventilatory assistance in proportion to patient effort. NAVA has been increasingly used for critically ill patients, but it has not been evaluated during spontaneous breathing trials (SBT). We designed a pilot trial to assess the feasibility of using NAVA during SBTs, and to compare the breathing pattern and patient-ventilator asynchrony of NAVA with Pressure Support (PSV) during SBTs. Methods: We conducted a crossover trial in the ICU of a university hospital in Brazil and included mechanically ventilated patients considered ready to undergo an SBT on the day of the study. Patients underwent two SBTs in randomized order: 30 min in PSV of 5 cmH(2)O or NAVA titrated to generate equivalent peak airway pressure (Paw), with a positive end-expiratory pressure of 5 cmH(2)O. The ICU team, blinded to ventilatory mode, evaluated whether patients passed each SBT. We captured flow, Paw and electrical activity of the diaphragm (EAdi) from the ventilator and used it to calculate respiratory rate (RR), tidal volume (VT), and EAdi. Detection of asynchrony events used waveform analysis and we calculated the asynchrony index as the number of asynchrony events divided by the number of neural cycles. Results: We included 20 patients in the study. All patients passed the SBT in PSV, and three failed the SBT in NAVA. Five patients were reintubated and the extubation failure rate was 25% (95% CI 9-49%). Respiratory parameters were similar in the two modes: VT = 6.1 (5.5-6.5) mL/Kg in NAVA vs. 5.5 (4.8-6.1) mL/Kg in PSV (p = 0.076) and RR = 27 (17-30) rpm in NAVA vs. 26 (20-30) rpm in PSV, p = 0.55. NAVA reduced AI, with a median of 11.5% (4.2-19.7) compared to 24.3% (6.3-34.3) in PSV (p = 0.033). Conclusions: NAVA reduces patient-ventilator asynchrony index and generates a respiratory pattern similar to PSV during SBTs. Patients considered ready for mechanical ventilation liberation may be submitted to an SBT in NAVA using the same objective criteria used for SBTs in PSV. (AU)

• FAPESP's process: 11/20225-1 - Performance of NAVA as lung protective mechanical ventilation in patients with acute respiratory distress syndrome
• Grantee: Juliana Carvalho Ferreira
• Support Opportunities: Regular Research Grants