Noninvasive ventilation through a helmet in postextubation hypoxemic patients: physiologic comparison between neurally adjusted ventilatory assist and pressure support ventilation
Neurally adjusted ventilatory assist (NAVA) has been shown to improve patient–ventilator interaction and reduce asynchronies in intubated patients, as opposed to pressure support ventilation (PSV). This is a short-term head-to-head physiologic comparison between PSV and NAVA in delivering noninvasive ventilation through a helmet (h-NIV), in patients with postextubation hypoxemic acute respiratory failure.
Ten patients underwent three 20-min trials of h-NIV in PSV, NAVA, and PSV again. Arterial blood gases (ABGs) were assessed at the end of each trial. Diaphragm electrical activity (EAdi) and airway pressure (Paw) were recorded to derive neural and mechanical respiratory rate and timing, inspiratory (delayTR-insp) and expiratory trigger delays (delayTR-exp), time of synchrony between diaphragm contraction and ventilator assistance (timesynch), and the asynchrony index (AI).
ABGs, peak EAdi, peak Paw, respiratory rate, either neural or mechanical, neural timing, and delayTR-exp were not different between trials. Compared with PSV, with NAVA the mechanical expiratory time was significantly shorter, while the inspiratory time and duty cycle were greater. Timesynch was 0.79 ± 0.35 s in NAVA versus 0.60 ± 0.30 s and 0.55 ± 0.29 s during the PSV trials (p < 0.01 for both). AI exceeded 10% during both PSV trials, while not in NAVA (p < 0.001).
Compared with PSV, NAVA improves patient–ventilator interaction and synchrony, with no difference in gas exchange, respiratory rate, and neural drive and timing.
KeywordsNoninvasive ventilation Helmet Patient–ventilator interaction Patient–ventilator asynchrony Neurally adjusted ventilatory assist (NAVA) Pressure support ventilation (PSV)
- 1.Evans TW (2001) International consensus conferences in intensive care medicine: non-invasive positive pressure ventilation in acute respiratory failure. Organised jointly by the American Thoracic Society, the European Respiratory Society, the European Society of Intensive Care Medicine, and the Societe de Reanimation de Langue Francaise, and approved by the ATS Board of Directors. Intensive Care Med 27:166–178PubMedCrossRefGoogle Scholar
- 2.Squadrone E, Frigerio P, Fogliati C, Gregoretti C, Conti G, Antonelli M, Costa R, Baiardi P, Navalesi P (2004) Noninvasive versus invasive ventilation in COPD patients with severe acute respiratory failure deemed to require ventilatory assistance. Intensive Care Med 30:1303–1310PubMedCrossRefGoogle Scholar
- 6.Antonelli M, Conti G, Pelosi P, Gregoretti C, Pennisi MA, Costa R, Severgnini P, Chiaranda M, Proietti R (2002) New treatment of acute hypoxemic respiratory failure: noninvasive pressure support ventilation delivered by helmet—a pilot controlled trial. Crit Care Med 30:602–608PubMedCrossRefGoogle Scholar
- 7.Antonelli M, Pennisi MA, Pelosi P, Gregoretti C, Squadrone V, Rocco M, Cecchini L, Chiumello D, Severgnini P, Proietti R, Navalesi P, Conti G (2004) Noninvasive positive pressure ventilation using a helmet in patients with acute exacerbation of chronic obstructive pulmonary disease: a feasibility study. Anesthesiology 100:16–24PubMedCrossRefGoogle Scholar
- 16.Terzi N, Pelieu I, Guittet L, Ramakers M, Seguin A, Daubin C, Charbonneau P, du Cheyron D, Lofaso F (2010) Neurally adjusted ventilatory assist in patients recovering spontaneous breathing after acute respiratory distress syndrome: physiological evaluation. Crit Care Med 38:1830–1837PubMedCrossRefGoogle Scholar
- 26.Costa R, Navalesi P, Spinazzola G, Ferrone G, Pellegrini A, Cavaliere F, Proietti R, Antonelli M, Conti G (2010) Influence of ventilator settings on patient–ventilator synchrony during pressure support ventilation with different interfaces. Intensive Care Med 36:1363–1370PubMedCrossRefGoogle Scholar