Diaphragmatic Electromyography Analysis During Two Different Mechanical Ventilation Techniques in Patients with Neuromuscular Diseases

Abstract-The aim of the present study is to analyse changes in the diaphragmatic electromyography integral, as a direct expression of the patients inspiratory effort and index of neural respiratory drive, and parameters associated with ventilatory function in patients with prolonged weaning under Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatoy Assist (NAVA). Five patients affected by neuromuscular diseases were recruited. Each patient underwent a sequence of decreasing inspiratory support levels under NAVA and PSV, randomly assigned, from a baseline to a final level. At baseline, the value of diaphragmatic electromyography integral was higher under NAVA compared to PSV and increased in both ventilation modes progressing to final level. Higher values of inspiratory time and neural inspiratory time were observed in PSV at final level compared to baseline level. Conversely, a significant decrease of neural inspiratory time from baseline level to final level was observed in NAVA. Tidal volume at final level was significantly lower than at baseline level in both ventilation modes. These preliminary results show that in prolonged weaning patients affected by neuromuscular disease NAVA ventilation is associated to a higher diaphragmatic electromyography activity compared to PSV with same level of ventilation and subjective comfort

Physiologic response to various levels of pressure support and NAVA in prolonged weaning

none5noneVagheggini G; Mazzoleni S; Vlad Panait E; Navalesi P; Ambrosino NVagheggini, G; Mazzoleni, S; Vlad Panait, E; Navalesi, P; Ambrosino,

Confronto di tre modalità di ventilazione meccanica assistita in pazienti con difficoltoso svezzamento

XII Congresso Nazionale Unione Italiana Pneumologia (UIP)/ XLI Congresso Nazionale Associazione Italiana Pneumologi Ospedalieri (AIPO), Bologna, Italy, November 30-December 3, 2011

Physiologic response to various levels of pressure support and NAVA in prolonged weaning

Neurally adjusted ventilatory assist (NAVA) is a mode of ventilation wherein the delivered assistance is proportional to diaphragm electrical activity (EAdi) throughout inspiration. We assessed the physiologic response to varying levels of NAVA and pressure support ventilation (PSV) in 13 tracheostomised patients with prolonged weaning. Each patient randomly underwent 8 trials, at four levels of assistance either in PSV and NAVA. i - high (no dyspnoea and/or distress); iv - low (associated with dyspnoea and/or distress; ii and iii - at ∼75% and ∼25% of the difference between high and low support respectively. We measured tidal volume (VT), peak EAdi, (EAdipeak) and airway pressure, ineffective efforts and breathing pattern variability. With both NAVA and PSV, decreasing assistance resulted in parallel significant increase in EAdipeak associated with a concomitant reduction in VT and minute ventilation in PSV, but not in NAVA. VT variability significantly increased when reducing ventilatory assistance in PSV only, while remained unchanged varying the NAVA level. The ineffective triggering index was not significantly different between the two modes. In patients with prolonged weaning, with the specific settings adopted, compared to PSV, NAVA reduced the risk of over-assistance and overall improved patient-ventilator interaction, while not significantly affecting patient-ventilator synchrony

Diaphragmatic electromyography analysis during two different mechanical ventilation techniques in patients with neuromuscular diseases

The aim of the present study is to analyse changes in the diaphragmatic electromyography integral, as a direct expression of the patients inspiratory effort and index of neural respiratory drive, and parameters associated with ventilatory function in patients with prolonged weaning under Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatoy Assist (NAVA). Five patients affected by neuromuscular diseases were recruited. Each patient underwent a sequence of decreasing inspiratory support levels under NAVA and PSV, randomly assigned, from a baseline to a final level. At baseline, the value of diaphragmatic electromyography integral was higher under NAVA compared to PSV and increased in both ventilation modes progressing to final level. Higher values of inspiratory time and neural inspiratory time were observed in PSV at final level compared to baseline level. Conversely, a significant decrease of neural inspiratory time from baseline level to final level was observed in NAVA. Tidal volume at final level was significantly lower than at baseline level in both ventilation modes. These preliminary results show that in prolonged weaning patients affected by neuromuscular disease NAVA ventilation is associated to a higher diaphragmatic electromyography activity compared to PSV with same level of ventilation and subjective comfort

Outcomes of difficult-to-wean subjects after cardiac surgery

BACKGROUND: The need for prolonged mechanical ventilation (PMV) after cardiac surgery is still a common problem. We hypothesized that subjects who required PMV after a single surgery (either coronary artery bypass grafting or valve surgery) would have better outcomes than those who had experienced both revascularization and valve surgery. METHODS: We retrospectively analyzed the characteristics and outcomes for patients consecutively admitted to our weaning unit (WU) after cardiac surgery between December 2007 and August 2012. Subjects' data were analyzed according to the number of procedures. Group 1 included subjects who had undergone a single surgery (valvular replacement or myocardial revascularization). Group 2 included subjects who had undergone combined surgery (valvular replacement and myocardial revascularization). Data for PMV subjects who were transferred to the WU for reasons other than cardiac surgery in the same period are also reported. RESULTS: Of 584 PMV subjects admitted, 35 (5.9%, 19 in group 1 and 16 in group 2) were referred after cardiac surgery. At WU admission, group 2 showed significantly more comorbidities and a greater clinical severity than group 1. Compared with group 1, group 2 showed a significantly lower weaning rate (43.7% vs 78.9%, P = .003) and a higher in-hospital mortality (31.3% vs 5.3%, P = .04). The overall 6-month survival for subjects of group 1 was 73.7% compared with 37.5% for subjects in group 2 (P = .02). Adjusting for comorbidities and clinical severity, the difference between the 2 groups did not reach statistical significance for either the weaning rate or the overall 6-month survival. At discharge, health status, as assessed by means of functional independence measure, was significantly better in group 1 than in group 2 (P = .035). CONCLUSIONS: These results suggest that patients needing PMV after combined cardiac surgery may suffer worse outcomes than those needing PMV after simple cardiac surgery