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Systematic review

Effect of long-term mechanical ventilation (LTMV) part 3 – COPD and cystic fibrosis

Norwegian Knowledge Centre for the Health Services has prepared three consecutive reports about LTMV. This is the third report in the series in which we review the effects of LTMV for patients with cystic fibrosis or COPD. The report overview two systematic reviews – one about the effect of LTMV for patients with cystic fibrosis and one about LTMV for patients with stable COPD.

Norwegian Knowledge Centre for the Health Services has prepared three consecutive reports about LTMV. This is the third report in the series in which we review the effects of LTMV for patients with cystic fibrosis or COPD. The report overview two systematic reviews – one about the effect of LTMV for patients with cystic fibrosis and one about LTMV for patients with stable COPD.


Key message

Patients who fail to maintain adequate respiration by themselves may need long-term mechanical ventilation (LTMV) for shorter or longer periods. Recent Norwegian data suggests considerable regional differences in the indication for initiation of LTMV.

Norwegian Knowledge Centre for the Health Services has prepared three consecutive reports about LTMV. This is the third report in the series in which we review the effects of LTMV for patients with cystic fibrosis or COPD. The report overview two systematic reviews – one about the effect of LTMV for patients with cystic fibrosis and one about LTMV for patients with stable COPD.

  • Current evidence does not suggest that LTMV is associated with improved survival or reduced need for hospitalisation in patient with stable COPD, but the quality of the evidence is too low to allow firm conclusions
  • LTMV probably have little or no effect on arterial blood gas values among patients with stable COPD
  • We need more evidence before concluding how LTMV affect sleep efficiency and quality of life in patients with stable COPD, and whether the effect of LTMV among patients with stable COPD is affected by the time selected for initiation of therapy
  • We need more evidence before concluding about the effectiveness of LTMV on survival, hospitalisation, sleep efficiency and quality of life in patients with cystic fibrosis

Summary

Background and objectives

Patients with a variety of disorders may require long-term mechanical ventilation (LTMV). The potential users are heterogeneous in terms of pathophysiology, age, and prognosis. Recent Norwegian data suggests that 19.9 LTMV-users per 100 000 inhabitants. Patients with COPD constitute the largest group of LTMV-users accounting for 23.7 percent of all registered users.

The indications for treatment with LTMV are in some cases obvious. Frequently, however, the need for LTMV is less obvious with patients only needing ventilator support some hours each day, for example during the night. The medical indications underlying initiation of LTMV are unclear and Norwegian data show substantial regional variations in the use of LTMV.

In two previous reports, we summarized the evidence for the use of LTMV among patients with neuromuscular disease, central respiratory failure, chest wall disorders, or obesity hypoventilation syndrome (OHS). In this third report, we focus on patients with lung disease (COPD or cystic fibrosis). Our primary interest lays in the patient centered outcomes survival, quality of life, hospitalization and sleep efficiency.

 

Method

We searched for systematic reviews and primary studies in MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, DARE, HTA, Cochrane CENTRAL, and ISI Web of Science. Two reviewers independently screened all titles and abstracts, and selected relevant systematic reviews and primary studies. We identified two systematic reviews that covered our objectives, and we assessed the quality of these reviews according to a checklist. We assessed the overall quality of the evidence for the use of LTMV by using GRADE.

 

Results

In this report, we present results based on two systematic reviews – one about patients with cystic fibrosis (search updated February 2013) and one about patients with COPD (search updated August 2012).

The systematic review about LTMV for patients with stable COPD summarized seven randomized trials (245 participants). The overview concludes that there are no consistent results suggesting that nocturnal LTMV contribute to significant improvement in quality of life, sleep efficiency, gas exchange and lung function in the short term (three months). The review authors did not find evidence for a long-term effect of LTMV on quality of life, gas exchange and lung function either, but these results are imprecise due to few available studies with few included patients.

The included review about LTMV and stable COPD did not report survival and hospitalization even though three of the included trials reported on these outcomes. Consequently, we decided to extract these data from the original trials. We identified three trials reporting 1-3 year mortality. Taken together, they did not show a statistically significant effect of nocturnal non-invasive LTMV on mortality (RR 0.89; 95 % CI 0.69 to 1.15), but we considered that the quality of the evidence was too low to allow firm conclusions. Neither did we find difference in the mean number of hospitalizations in LTMV group compared with the control group, but also for this outcome the quality of the evidence is too low to allow reliable conclusions.

The included systematic review summarized three randomized crossover trials about LTMV and patients with cystic fibrosis (27 participants). Two of the three primary studies had too short follow-up to (one night studies) to give information about the outcomes we defined as primary for this report. In the third study, the patients received nocturnal non-invasive ventilation, oxygen and air for three periods of six weeks respectively. According to the review authors, data on survival and hospitalizations were not reported in the trial, but it showed improved scores for some quality of life domains and increased exercise performance following LTMV compared with air control. The quality of the evidence was insufficient to allow firm conclusions.

 

Discussion

Norwegian and Swedish register data shows considerable local and regional variation in the use of LTMV, probably reflecting differences in the criteria for initiation of LTMV. The variation also illustrates that it is not always obvious when treatment with LTMV should be initiated, and there is a need for research to assess when, and for whom, LTMV is an appropriate treatment strategy. 

As expected, we found limited research investigating the long-term effect of LTMV among patient with cystic fibrosis. It is a relatively rare condition making it difficult to recruit participants to trials. For these patients, mechanical ventilation is usually used to stabilize hypoxemia / acidosis and as a bridge towards transplantation.

The effect of LTMV for patients with stable COPD has been investigated in several methodically robust trials. By now, we can be quite confident that standard LTMV does not contribute significant short-term (3 months) improvements in the gas exchange. The long-term (> one year) effect of LTMV seems more uncertain, particularly with regard to important patient-related outcomes such as survival, quality of life and hospitalization. Moreover, our current knowledge provides a limited basis for evaluating various LTMV techniques against one another. For example, it is unclear whether high intensity ventilation (IPAP between 20 and 40 cmH 2 O) may be associated with better outcomes than standard LTMV. There is also a need to investigate whether the beneficial effects of LTMV are more evident when used as a component in a more comprehensive rehabilitation strategy.

 

Conclusion

  • Current evidence does not suggest that LTMV is associated with improved survival or reduced need for hospitalisation in patient with stable COPD, but the quality of the evidence is too low to allow firm conclusions.  
  • LTMV probably have little or no effect on arterial blood gas values among patients with stable COPD
  • We need more evidence before concluding how LTMV affect efficiency and quality of life in patients with stable COPD, and whether the effect of LTMV among patients with stable COPD is affected by the time selected for initiation of therapy
  • We need more evidence before concluding about the effectiveness of LTMV on survival, hospitalisation, sleep efficiency and quality of life in patients with cystic fibrosis.

Further research on the effects of LTMV among patients with stable COPD or cystic fibrosis is needed before we can draw firm conclusion about the effect. New trials should be designed with a particular interest in patient-centred outcomes such as survival, quality of life and hospitalizations.

 

    About this publication

  • Year: 2014
  • Authors Brurberg KG, Dahm KT.
  • ISSN (digital): 1890-1298
  • ISBN (digital): 978-82-8121-687-7