The Role of Heliox in Intensive Care Fekri Abroug CHU F.Bourguiba Monastir. Tunisia

Helium + Oxygen = Heliox n Helium- inert low MW gas, insoluble at 1 ATM n low density (0.179 μ poise) vs. air (1.293) and O 2 (1.429) n  density-  turbulent flow

Heliox n Discovered in 1895 n 1934 used for airway obstruction (Barach) n Limited use if pt needs  O 2 n Try to deliver at least 60% helium, ideally 80% West JB, Respiratory Physiology, The Essentials, 6 th ed. 2000, Lippincott, p. 91.

Heliox in acute asthma

Pathophysiology in asthma

Effects of Heliox n Reduces the Work of Breathing n Reduces the pic pressure n Reduces the dynamic hyperinflation (auto-PEP)

n 7 heterogeneous studies: –4 studies where heliox served as a vector of nebuliserd ß2-agonists –3 studies where heliox replaced air –4 studies where heliox/air mixture: 80/20 –3 studies where heliox/air mixture : 70/30 –Administration duration: minutes –6 randomised studies, 1 non randomised n PEF was not systematically corrected (1.32) n Overall: poor methodologic quality

Heliox in non-intubated asthmatics Effects on pulmonary function Rodrigo. Cochrane Database jan 2005

Heliox in non-intubated asthmatics Effects on hospital admissions

Heliox n No effect on pulmonary function although heterogeneous studies (trend toward favourable effect when Heliox is used for drug nebulisation) n Enhances the pulsus parodoxus in a pediatric study n No effect on admissions rate

The study evaluating Heliox in acute asthma remains to be performed Manthous. Chest 2003 n Only patients without improvement following the first ß2-agonists should be included (70% of overall population improve their respiratory function followin the first bronchodilator nebulisation n The study should include a large sample size (654 patients to demonstrate a reduction in the intubation rate from 1 to 0.2% (ß=80% & α=0.05)

Heliox in the prehospital setting Baseline evaluation

PEF variation (medians) Correction (1.32)

Heliox Acute Exacerbation of COPD

International Multicentric study: NIV/ Heliox in AECOPD n International Multicentric Study: –5 French Centers –1 Spanish Center –1 Italian Center –1 Tunisian Center n A prospective Controlled Study: Airox vs Heliox n Heliox administartion duration: duration of NIV n Evaluation Outcome: reduction in the intubation rate from 40% to 20% (estimated sample size: 200)

Heliox & NIV Ventilation n Many ventilators are not calibrated for Helium and underestimate TV.

Patients characteristics Airox N= 99 Heliox N=96 pH7.28± ±0.07 PaCO271.7±1573.3±18 SAPS II33±1132±11

Effects on intubation rate n Reduction of the intubation rate: 30.3% à 20.8% (p=0.13) n RRA: 10% (95%CI: -3%-21%) n NNT: 10 (95%CI: 5-33)

n Intubation: 20% (airox) vs 13% (heliox) n Hospitalisation costs: reduction of 3348$/patient

Meta-analysis: NIV Heliox-AECOPD n Reduction of the intubation rate: 26% to 18 %(p=0.09) n ARR: 8% (95%CI: -0.8%-17%) n NNT: 12(95%CI: ) Abroug &al (in press)

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