Document Detail

Patient-ventilator interaction during pressure support ventilation and neurally adjusted ventilatory assist.
MedLine Citation:
PMID:  20083921     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To compare the effect of pressure support ventilation and neurally adjusted ventilatory assist on breathing pattern, patient-ventilator synchrony, diaphragm unloading, and gas exchange. Increasing the level of pressure support ventilation can increase tidal volume, reduce respiratory rate, and lead to delayed ventilator triggering and cycling. Neurally adjusted ventilatory assist uses diaphragm electrical activity to control the timing and pressure of assist delivery and is expected to enhance patient-ventilator synchrony. DESIGN: Prospective, comparative, crossover study. SETTING: Adult critical care unit in a tertiary university hospital. PATIENTS: Fourteen nonsedated mechanically ventilated patients (n = 12 with chronic obstructive pulmonary disease). INTERVENTIONS: Patients were ventilated for 10-min periods, using two pressure support ventilation levels (lowest tolerable and +7 cm H2O higher) and two neurally adjusted ventilatory assist levels (same peak pressures and external positive end-expiratory pressure as with pressure support ventilation), delivered in a randomized order. MEASUREMENTS AND MAIN RESULTS: Diaphragm electrical activity, respiratory pressures, air flow, volume, neural and ventilator respiratory rates, and arterial blood gases were measured. Peak pressures were 17 +/- 6 cm H2O and 24 +/- 6 cm H2O and 19 +/- 5 cm H2O and 24 +/- 6 cm H2O with high and low pressure support ventilation and neurally adjusted ventilatory assist, respectively. The breathing pattern was comparable with pressure support ventilation and neurally adjusted ventilatory assist during low assist; during higher assist, larger tidal volumes (p = .003) and lower breathing frequencies (p = .008) were observed with pressure support ventilation. Increasing the assist increased cycling delays only with pressure support ventilation (p = .003). Compared with pressure support ventilation, neurally adjusted ventilatory assist reduced delays of ventilator triggering (p < .001 for low and high assist) and cycling (high assist: p = .004; low assist: p = .04), and abolished wasted inspiratory efforts observed with pressure support ventilation in six subjects. The diaphragm electrical activity and pressure-time product for ventilator triggering were lower with neurally adjusted ventilatory assist (p = .005 and p = .02, respectively; analysis of variance). Arterial blood gases were similar with both modes. CONCLUSIONS: Neurally adjusted ventilatory assist can improve patient-ventilator synchrony by reducing the triggering and cycling delays, especially at higher levels of assist, at the same time preserving breathing and maintaining blood gases.
Jadranka Spahija; Michel de Marchie; Martin Albert; Patrick Bellemare; St?phane Delisle; Jennifer Beck; Christer Sinderby
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Critical care medicine     Volume:  38     ISSN:  1530-0293     ISO Abbreviation:  Crit. Care Med.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-19     Completed Date:  2010-02-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  518-26     Citation Subset:  AIM; IM    
Critical Care Unit, Sacr?-Coeur Hospital, University of Montreal, Montreal, Quebec, Canada.
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MeSH Terms
Aged, 80 and over
Cross-Over Studies
Intermittent Positive-Pressure Ventilation / methods
Middle Aged
Positive-Pressure Respiration / methods*
Prospective Studies
Pulmonary Gas Exchange
Respiration, Artificial / methods*
Respiratory Rate
Tidal Volume
Comment In:
Crit Care Med. 2010 Feb;38(2):714-5   [PMID:  20083941 ]

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