140 likes | 357 Views
CAT review: ‘Heliox use in non-invasive COPD ventilation’ . Dr Andrew J Dalton CT2 South East Scotland. Maurizio M et al. A multicenter, randomised trial of noninvasive ventilation with helium-oxygen mixture in exacerbations of chronic obstructive lung disease. Crit Care Med 2010; 38:145-151.
E N D
CAT review: ‘Heliox use in non-invasive COPD ventilation’ Dr Andrew J Dalton CT2 South East Scotland
Maurizio M et al. A multicenter, randomised trial of noninvasive ventilation with helium-oxygen mixture in exacerbations of chronic obstructive lung disease. Crit Care Med 2010; 38:145-151
Background • Helium • Inert gas • Lower dense than nitrogen • Turbulent flow rate is improved by helium use • Helium can be used in upper airway obstruction to improve alveolar ventilation
Background (cont.) • Laminar flow is dependent on viscosity and independent of density • Therefore traditionally helium not thought to be of significant benefit in lower airway obstruction due to prevalence of lamina flow • However more recent studies had suggested there may be a benefit to oxygenation in COPD by reducing the work of breathing Laude EA et al. Am J Respir Crit Care Med. 2006 Apr;173(8):865-70 Jaber S et al. Am J Respir Crit Care Med. 2000 Apr;161(4):1191-1200
Trial • Study: Non-blinded, randomised controlled trial with intention-to-treat analysis • Patients: Recruited from 7 ICUs in France, Tunisia, Italy, Spain over 2 years
Inclusion/Exclusion criteria • Inclusion: • Known/suspected COPD and acute dyspnoea • PaCO2 > 45mmHg (6kPa) • Two of pH < 7.35, PaCO2 < 50mmHg (6.67kPa), respiratory rate >25/minute • Exclusion: • Respiratory arrest, need for immediate intubation, pneumothorax, life expectancy < 1 month, hypoxaemia requiring oxygen > 6L/min, inability to cooperate, upper airway obstruction, facial trauma, haemodynamic instability, pregnancy
Study groups • Control: • n=102 • Noninvasive bi-level airway pressure ventilation (NIV) applied via facemask with FiO2 0.35 • Experimental: • n=102 • NIV applied via facemask with helium-oxygen (HeO2) mixture with FiO2 0.35
Endpoints • Primary • Need for intubation • Secondary • Duration of NIV • Length of hospital stay • Mortality Patients were followed up for 28 days post enrolment
Methods • NIV was applied intermittently for at least 6hrs/day • Each NIV trial lasted between 30mins – 3hrs (depending on clinician judgement) • In between NIV trials patients in both groups breathed air-oxygen • Decision to intubate was based on the presence of predefined criteria, and once intubated all patients were ventilated with air/oxygen
Results • Analysis was performed on all patients in both groups • Chi-squared test used for proportions/rates, Wilcoxon’s rank sum test for ordinal variables, Student’s t test for normal variables, p≤0.05 considered significant
Analysis • Intubation rate did not significantly differ • No difference in mortality • No difference in duration of NIV, length of ICU stay (10.6 vs 10.9 days control) or length of hospital stay (19.1 vs 18.5 days control) • Additionally no significant difference noted in arterial blood gases • Subgroup analysis • Intubation rates were lower in patients receiving short NIV duration (<4 days) with heliox (18 of 57 vs 23 of 43, p=0.03) • Was suggested that any possible benefit from helium may be in the early stage of treatment
Summary • No evidence of improved NIV ventilation in COPD with helium in any measured outcome • No change of practice should be initiated based on this study • The authors suggest that any further research should be focussed on the subgroup identified, but no indication is given on how best to identify these patients initially
Thanks Any questions?