Chronic obstructive pulmonary disease: noninvasive ventilation decreased failure of weaning.

Clinical bottom line (level 1b)

  1. Patients with chronic obstructive pulmonary disease who were given noninvasive ventilation, were less likely to have weaning failure compared with those given invasive ventilation (NNT = 3 at 21 days) .
  2. Patients given noninvasive ventilation spend less time undergoing mechanical ventilation, than those given invasive ventilation.
Nava et al: Annals of Internal Medicine 1998; 128: 721-728
Expires November 2003

The study

Unblinded concealed randomised trial with intention-to-treat
Setting: three intensive care units, Italy

50 patients (aged mean 68 years, ?% male) chronic obstructive pulmonary disease who were admitted for acute relapse and who needed intubation. Acute relapse was: respiratory acidosis (pH = 7.33 while breathing room air); elevated bicarbonate levels; hypoxaemia (PaO2 = 45 mmHg while breathing room air); severe dyspnoea in the absence of an objectively documented cause, such as pneumonia or 1 of 11 nonoperative respiratory diagnoses (excluding chronic obstructive pulmonary disease) found in the Acute Physiology, Age and Chronic Health Evaluation (APACHE) III.

Excluded if
  • concomitant severe diseases, such as neurologic diseases other than hypercapnic encephalopathy
  • cancer and other systemic diseases
  • cardiac arrest
  • cardiogenic pulmonary oedema
  • cardiogenic shock
  • aortic aneurysm
  • acute myocardial infarction
  • gastrointestinal perforation, obstruction or bleeding
  • sepsis
  • trauma
  • metabolic coma
  • diabetic ketoacidosis
  • drug overdose
  • coagulopathy
  • other haematologic diseases
  • postoperative patients


    • Note:
  • To make the decision of whether intubation as objective as possible, the authors established criteria extrapolated from a previous study (Brochard et al). Major criteria for intubation were: respiratory arrest, loss of consciousness, psychometer agitation requiring sedation, haemodynamic instability with systolic blood pressure <70 mmHg or > 180 mmHg, and a heart rate of = 50 beats per minute and higher than the value recorded on admission, arterial pH = 7.30 and lower than value recorded at admission. PaO2 <45 mmHg despite oxygen supplementation, deterioration of one or more points in the neurologic score of the scale Kelly and Matthay, presence of weak cough reflex with accumulation of secretions.


    • Control Group: (n = 25, 25 analysed): after intubation, invasive ventilation was administered for 12 hours- standard settings for controlled ventilation were used: tidal volume, approximately 8 to 10 mL/kg; respiratory rate, 12 to 16 breaths/minute; inspired oxygen fraction (FiO2) as required to obtain an SaO2 of about 95%. Pressure support ventilation was then given for an additional 24 to 36 hours. Following the ventilation, a T-piece weaning trial was carried out in patients who were judged to have reached satisfactory neurologic status.
    Experimental Group: (n = 25, 25 analysed): noninvasive pressure support ventilation, followed by T-piece weaning

    100% followed for 21 days failure to wean
    Outcome notes:
    • failure to wean : weaning failure defined as respiratory rate >35 breaths/minute; PaO2 <50 mmHg for an FiO2 of 40%; heart rate>145 beats/minute or sustained increase or decrease in the heart rate of >20%; severe arrhythmia; systolic blood pressure >180 mmHg or <70 mmHg; agitation, anxiety or diaphoresis.

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    failure to wean weeks 13
    (52.0%)    		 4
    (16.0%)    		 69.0%
    (19.0% to 88.0%)    		 36.0%
    (11.7% to 60.3%)    		 3
    (2 to 9)

    Outcome Control Group
    (SD)    		 Experimental Group
    (SD)    		 Mean Difference
    (95% CI)
    mean number of days receiving mechanical ventilation 10.2
    (6.80)     		16.6
    (11.8)     		-6.40
    (-11.9 to -0.92)

    Citation

    1. Nava S, Ambrosino N, Clini E, et al: Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease: A randomized, controlled trial. Annals of Internal Medicine 1998; 128: 721-728
    Search Terms: COPD, chronic obstructive pulmonary disease and therapy in Medline
    Contributor: Clare Wotton and Musab Hayatli, November 1999
    Reviewer:

    Clinical Question.
    Patient COPD
    Intervention or Exposure noninvasive mechanical ventilation
    Comparison standard ventilation
    Outcome reduction in weaning time