Clinical effects of heliox administration for acute bronchiolitis in young infants. Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure. Nasal continuous positive airway pressure with heliox versus air oxygen in infants with acute bronchiolitis: a crossover study. Helium-oxygen improves Clinical Asthma Scores in children with acute bronchiolitis. Noninvasive therapy with helium-oxygen for severe bronchiolitis.
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). The purpose of this work was to evaluate the effects of administering either heliox or air oxygen in combination with nasal continuous positive airway pressure in infants with refractory bronchiolitis.
                We conducted a prospective, interventional, single-center, crossover study in a teaching hospital including infants 1 month to 2 years of age, consecutively admitted to the PICU from February 2004 to February 2005 for treatment of severe acute bronchiolitis unresponsive to therapy. Patients with a clinical score (Modified Wood's Clinical Asthma Score) of >5, arterial oxygen saturation of <92%, or transcutaneous CO(2) pressure of >50 mmHg despite supportive therapy, nebulized L-epinephrine, and heliox therapy through a nonrebreathing reservoir face mask were eligible. During the study period, 40 infants with bronchiolitis were admitted to the PICU; 12 fulfilled inclusion criteria. A predetermined balanced sequential allocation to either 30 minutes of treatment with nasal continuous positive airway pressure with heliox or to air-oxygen nasal continuous positive airway pressure was performed. Measurements were taken at baseline and after 30 minutes of each treatment.
                Baseline mean values were as follows: nasal continuous positive airway pressure of 7.2 cmH(2)O; clinical score of 7.7 points; transcutaneous CO(2) pressure of 61.6 mmHg; and arterial oxygen saturation of 88.6%, with the fraction of inspired oxygen at 35.4%. Clinical score, transcutaneous CO(2) pressure, and arterial oxygen saturation improved during the study time with both heliox-nasal continuous positive airway pressure and air-oxygen-nasal continuous positive airway pressure: after 1 hour, the clinical score fell 1.7 points, transcutaneous CO(2) pressure decreased 8.2 mmHg, and arterial oxygen saturation increased by 7.7%. Improvement in clinical score was double with heliox-nasal continuous positive airway pressure compared with the air-oxygen-nasal continuous positive airway pressure (2.12 vs 1.08 points), and the fall in the transcutaneous CO(2) pressure was greater with heliox-nasal continuous positive airway pressure compared with air-oxygen-nasal continuous positive airway pressure (9.7 vs 5.4 mm Hg). There was no difference in arterial oxygen saturation between groups. No patients required endotracheal intubation. No adverse effects attributable to either of the study interventions were detected.
                Nasal continuous positive airway pressure improves the clinical score and the CO(2) elimination of infants with refractory bronchiolitis. These positive effects are significantly enhanced when nasal continuous positive airway pressure is combined with heliox instead of air oxygen. Both techniques are noninvasive, seem safe, and may reduce the need for endotracheal intubation. To determine the efficacy of a helium-oxygen mixture in children admitted to the pediatric intensive care unit with acute respiratory syncytial virus (RSV) bronchiolitis.
                Randomized, double-blind, controlled, crossover study and nonrandomized, prospective study.
                A pediatric intensive care unit in a university hospital.
                Nonintubated children with signs of acute lower respiratory tract infection and a positive rapid immunoassay for RSV admitted to the pediatric intensive care unit.
                Treatment with either helium-oxygen or air-oxygen was administered in random order for 20 mins. Nonrandomized patients received helium-oxygen as initial therapy.
                Clinical Asthma Score, respiratory rate, heart rate, and pulse oximetry oxygen saturation values were recorded at baseline (before randomization) and at the end of each 20-min treatment period (helium-oxygen or air-oxygen). Nonrandomized patients were studied 20 mins into helium-oxygen delivery. Eighteen patients were studied, 13 of whom were randomized. Five children with severe bronchiolitis (Clinical Asthma Score of > or =6) were initially given helium-oxygen and scored at 20 mins. Mean Clinical Asthma Score was 3.04 (range 1 to 7.5) in the 13 randomized patients and 4.25 (range 1 to 9) in the 18 patients overall. Clinical Asthma Score decreased in the 13 randomized patients (mean 0.46, p < .05) and in the 18 patients overall (mean 1.23, p < .01) during helium-oxygen delivery. In randomized patients with Clinical Asthma Scores of <6 (n = 12), a positive correlation (rs = .72) was observed between the Clinical Asthma Score at baseline and the change in Clinical Asthma Score during helium-oxygen administration (p = .009). Respiratory rate and heart rate decreased during helium-oxygen treatment but were not statistically significant. No complications occurred during helium-oxygen delivery.
                Inhaled helium-oxygen improves the overall respiratory status of children with acute RSV lower respiratory tract infection. In patients with mild-to-moderate bronchiolitis (Clinical Asthma Scores of <6), the beneficial effects of helium-oxygen were most pronounced in children with the greatest degree of respiratory compromise. 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.
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.