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Inhaled NO in ALI / ARDS

Citation/s: Troncy E. Collet JP. Shapiro S. Guimond JG. Blair L. Ducruet T. Francoeur M. Charbonneau M. Blaise G. Inhaled nitric oxide in acute respiratory distress syndrome: a pilot randomized controlled study. American Journal of Respiratory & Critical Care Medicine. 1998;157(5 Pt 1):1483-8.

Lead author's name and fax: Troncy E

Three-part Clinical Question:

1.      The patients- ALI / ARDS with LIS > 2.5 (severe ARDS according to Murray score). Age 18-75 years

2.       The treatment- Inhaled NO at doses of 0.5-40ppm

3.       The outcome- reversal of ALI / ARDS with extubation at 30 days and mortality

 

Search Terms: ARDS; Nitric oxide, inhaled.

The Study: Non-blinded randomised controlled trial with intention-to-treat.

The Study Patients: ALI / ARDS with MLIS > 2.5 (severe), 18-75 years of age on SIMV or pressure controlled ventilation and weaned on SIMV.
Control group (N = 15; 15 analysed): SIMV or pressure controlled ventilation with standardised weaning protocol on SIMV and extubated at ASB <10cmH2O, PEEP <5 and FiO2 < 0.5. All patients had inhaled NO dose titration with a >20% rise in PaO2 counted as significant. All patients were analysed according to group regardless of response to dose titration.
Experimental group (N = 15; 15 analysed): Ventilation and weaning as above plus addition of inhaled NO at doses of 0.5 to 40ppm. Dose titration performed daily and lowest dose used. Inhaled NO weaning protocol also used.

The Evidence:

Comments:
This small study that was not powered to determine either their primary or secondary outcomes. Was unable to demonstrate improvement in outcome related to inhaled NO therapy in ALI / ARDS.

EBM Comments:

1. Do the methods allow the adequate testing of the hypothesis? No, sample size is too small
2. Do the statistical tests correctly test the results to allow differentiation of statistically significant result? Difficult to understand but they seem appropriate.
3. Are conclusions valid in light of results? They conclude that: “Our study confirms the initial efficacy of inhaled NO on lung function but does not show any significant difference between groups after the first day of follow-up. We observed a more rapid resolution of pulmonary changes in blood gas criteria in ARDS, which was not followed by beneficial effects on lung function, duration of mechanical ventilation, and mortality…. demonstrating an effect of inhaled NO on ARDS mortality in this population would be difficult to achieve even with a large multi-centre trial”. They may have over stated the results in terms of efficacy but rest of conclusion are probably valid.
4. Did results get omitted, and why? No.
5. Did they suggest areas of further research? Yes, “We suggest that further studies should focus on early treatment (when the condition is more likely to be reversible) and on the use of inhaled NO on selected populations such as patients with ARDS induced by direct lung injury or those responsive to the therapy whatever the etiology. These populations should benefit the most from the use of inhaled NO with a putative effect not only on gas exchange but also on mortality”. These seem reasonable.
6. Did they make recommendations based on results and were they appropriate? No they did not.
7. Is this study relevant to my clinical practice? Probably, as they include ALI / ARDS with similar severity of illness to our patients but results lack significance and thus applicability due to small numbers.
8. What level of evidence does this study represent? Level 1^-
9. What grade of recommendation can I make on this result alone? Grade B
10. What grade of recommendation can I make when this study is considered along with other available evidence? Grade A
11. Should I change my practice because of these results? No, unless you use inhaled NO in similar groups in which case you should review your current use.
12. Should I audit my current practice because of these results? Yes, if you use inhaled NO you should audit your practice and outcomes.

Appraised by: Dr Brian H Cuthbertson, ICU, Aberdeen Royal Infirmary; 24 February 2004. 

Email: b.h.cuthbertson@abdn.ac.uk

Kill or Update By: February 2006

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