Clinical effects of heliox administration for acute bronchiolitis in young infants. Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure. Noninvasive therapy with helium-oxygen for severe bronchiolitis. Randomized trial of the use of heliox as a driving gas for updraft nebulization of bronchodilators in the emergent treatment of acute exacerbations of chronic obstructive pulmonary disease. Evaluation of heliox in children hospitalized with acute severe asthma. A randomized crossover trial.
To assess the effect of heliox, a helium-oxygen mixture, on respiratory distress symptoms in young infants.
                Prospective, randomized, double-blind study.
                Pediatric ICU (PICU) of a university hospital.
                Twenty infants, all < 3 months old, admitted to the PICU with moderate-to-severe acute respiratory syncytial virus bronchiolitis.
                All infants were randomly and blindly assigned to inhale either heliox or an air-oxygen mixture (airox) for 1 h under an oxyhood.
                After 1 h, the respiratory distress score was significantly lower in the heliox group compared with the airox group (3.05 vs 5.5, p < 0.01), with a significant reduction in accessory muscles use (p < 0.05) and expiratory wheezing (p < 0.01). In contrast, inspiratory breath sounds and cyanosis did not significantly differ between groups. The ex-premature infants of the heliox group had a higher respiratory distress score at baseline compared with the term infants of this group (5.8 vs 5.2, p < 0.05) and a comparable decrease in the score at 60 min.
                In young infants, even those born prematurely, heliox breathing induced a rapid reduction in accessory muscles use and expiratory wheezing. Further studies are needed to confirm the decreased respiratory muscle work of breathing during heliox inhalation in this population. Respiratory syncytial virus (RSV) lower respiratory tract disease is characterised by narrowing of the airways resulting in increased airway resistance, air-trapping and respiratory acidosis. These problems might be overcome using helium-oxygen gas mixture. However, the effect of mechanical ventilation with heliox in these patients is unclear. The objective of this prospective cross-over study was to determine the effects of mechanical ventilation with heliox 60/40 versus conventional gas on respiratory system resistance, air-trapping and CO2 removal.
                Mechanically ventilated, sedated and paralyzed infants with proven RSV were enrolled within 24 hours after paediatric intensive care unit (PICU)admission. At T = 0, respiratory system mechanics including respiratory system compliance and resistance, and peak expiratory flow rate were measured with the AVEA ventilator. The measurements were repeated at each interval (after 30 minutes of ventilation with heliox, after 30 minutes of ventilation with nitrox and again after 30 minutes of ventilation with heliox). Indices of gas exchange (ventilation and oxygenation index) were calculated at each interval. Air-trapping (defined by relative change in end-expiratory lung volume) was determined by electrical impedance tomography (EIT) at each interval.
                Thirteen infants were enrolled. In nine, EIT measurements were performed. Mechanical ventilation with heliox significantly decreased respiratory system resistance. This was not accompanied by an improved CO2 elimination, decreased peak expiratory flow rate or decreased end-expiratory lung volume. Importantly, oxygenation remained unaltered throughout the experimental protocol.
                Respiratory system resistance is significantly decreased by mechanical ventilation with heliox (ISCRTN98152468). To determine whether noninvasive therapy using a helium-oxygen mixture reduces the use of positive-pressure ventilation in the treatment of respiratory failure caused by severe bronchiolitis.
                This was a multicenter, randomized, double-blind, placebo-controlled trial that recruited infants in 4 pediatric intensive care units (PICUs). A total of 39 nonintubated infants with severe bronchiolitis caused by respiratory syncytial virus (RSV) were randomly assigned within 8 hours of PICU admission to receive a helium-oxygen mixture (helium group) or an air-oxygen mixture (control group) through an inflatable head hood. The primary study outcome was the requirement for positive pressure mechanical ventilation. Results were compared using Fisher's exact test.
                No differences were noted between the control and helium groups with respect to age (1.0 vs 1.1 months), prematurity, or family history of asthma or smoking. Positive pressure ventilation was judged necessary for 4 of the 21 (19.0%) infants in the control group and in 4 of the 18 (22.2%) in the helium group (relative risk = 1.17; 95% confidence interval = 0.34 to 4.01).
                This study did not detect any differences between the patients in the helium group and the control group with respect to the rate of positive-pressure ventilation. To determine whether the bronchodilator effects of albuterol and ipratropium bromide are greater if updraft nebulization is driven by 80% helium and 20% oxygen (HELIOX) than if driven by compressed room air (AIR) during the treatment of an acute exacerbations of chronic obstructive pulmonary disease (COPD).
                The emergency department of a 750-bed inner-city community hospital.
                Over a 12-month period, a convenience sample of 50 normoxic patients presenting with signs and symptoms of an acute exacerbation of COPD were prospectively randomized to receive either HELIOX or AIR as the driving gas for updraft nebulization of a mixture of albuterol 2.5 mg and ipratropium bromide 0.5 mg. Additional aerosol treatments with albuterol 2.5 mg were given at 20, 40, and 120 mins after randomization using the assigned gas. Spirometry was obtained while breathing room air before the first treatment (baseline) and at 1 hr and 2 hrs after the initiation of treatment. The primary measure of efficacy was the change in percent of predicted forced expiratory volume in 1 sec (FEV1) over the treatment period. A secondary measure of efficacy was the change in percentage of predicted forced expiratory flow after 25% to 75% of vital capacity had been expelled (FEF25-75).
                Twenty-five patients were randomized to each treatment group. Three patients (1 HELIOX, 2 AIR) were unable to complete the study. The baseline FEV1was 44% (95% confidence interval, 35% to 52%) of predicted in the HELIOX group and 39 (31% to 46%) of predicted in the AIR group. There were no adverse outcomes observed in either the HELIOX group or the AIR group. There were no significant differences in the change of FEV1 between the two groups by either the 1 hr or 2 hr time point (1 hr, HELIOX + 10% [7% to 13%], AIR + 9% [5% to 13%]; 2 hr HELIOX + 10% [6% to 15%], AIR + 10% [6% to 14%]). The improvement in FEF25-75 was significantly greater in the HELIOX group than in the AIR group at both the 1 hr time point (HELIOX + 14% [7% to 22%] vs. AIR + 7% [3% to 10%], p = .05) and at the 2 hr time point (HELIOX + 15% [8% to 21%] vs. AIR + 7% [4% to 11%], p = .05).
                Use of HELIOX as a driving gas for the updraft nebulization of bronchodilators during the first 2 hrs of treatment of an acute COPD exacerbation failed to improve FEV1 faster than the use of AIR. The faster improvement in FEF25-75 during the first 2 hrs of treatment was small and of uncertain clinical significance. To determine whether breathing a blend of 70% helium:30% oxygen (heliox) would improve pulmonary function, decrease clinical score, and improve the sensation of dyspnea in children hospitalized with acute severe asthma.
                Prospective, randomized, double-blind, crossover study.
                The inpatient pediatric service of a military, tertiary care, teaching hospital.
                Children 5 to 18 years who required hospital admission for treatment of acute asthma.
                All patients received 5 mg of nebulized albuterol every 1 to 4 h, with a dose given within 30 min of the start of the study, and IV administered methylprednisolone. Patients breathed heliox and a 30% oxygen-enriched air mixture for 15 min each in random order.
                Clinical score, dyspnea score, oxygen saturation, heart rate, and respiratory rate, followed by FVC, FEV1, peak expiratory flow rate (PEFR), and, mean midexpiratory flow rate (FEF25-75) were obtained at study entry, 15 min after breathing the first gas mixture (heliox or air per randomization), 15 min after breathing the second mixture, and again 15 min after stopping the second gas mixture (study end values). Eleven children were enrolled, and all completed the study. There were no significant differences between study entry and study end spirometric values. Using the paired t test, we found no significant differences between mean values (SD) of FEV1 and FVC obtained while breathing heliox vs air; FEV1-heliox, 53% (18%) of the predicted value; FEV1-air, 52% (16%) of the predicted value (p = 0.36); FVC-heliox, 69% (22%) of the predicted value; and FVC-air, 70% (21%) of the predicted value (p = 0.50). The differences in values for PEFSR and FEF25-75 while breathing heliox vs air were small but did reach statistical significance in favor of heliox: PEFR-heliox, 56% (20%) of the predicted value; PEFR-air, 50% (16%) of the predicted value (p = 0.04); FEF25-75-heliox, 32% (13%) of the predicted value; and FEF25-75-heliox, 29% (11%) of the predicted value (p = 0.006). Heliox had no effect on either clinical or dyspnea scores.
                The short-term inhalation of heliox did not benefit this group of children hospitalized with acute, severe asthma.
Current evidence suggests that the addition of heliox therapy may significantly reduce a clinical score evaluating respiratory distress in the first hour after starting treatment in infants with acute RSV bronchiolitis. Nevertheless, there was no reduction in the rate of intubation, in the need for mechanical ventilation, or in the length of PICU stay. Further studies with homogeneous logistics in their heliox application are needed. Such studies would provide necessary information as to the appropriate place for heliox in the therapeutic schedule for severe bronchiolitis.