Not Just for Balloons Anymore

Vol. 16 •Issue 3 • Page 50
Not Just for Balloons Anymore

Clinicians study the use of helium in treating pediatric airway disorders.

Discovered during a solar eclipse in 1868 and later named after the Greek god of the sun, helium has emerged as a treatment for acute airway obstruction in children.

Alvan Leroy Barach, MD, first described helium’s clinical use in 1935 when he used it to successfully treat four adults with asthma and two infants with upper airway obstruction (UAO).1 Following that, few reports of its use appeared until the late 1970s. By the 1990s, the use of helium-oxygen (heliox) mixtures had resurfaced as an adjunctive therapy during asthma management.2,3

Helium has no bronchodilating or anti-inflammatory properties. In fact, its medicinal use comes from its physical characteristics. (See Sidebar, page 52.) These characteristics, the same ones that allow us to entertain ourselves with a helium-induced “Donald Duck voice,” also allow clinicians in the emergency department and the pediatric intensive care unit to effectively manage common pulmonary pathologies in children.4

Starting with UAO and working down the tracheobronchial tree to the lower airway pathologies such as bronchiolitis and asthma, let’s review the clinical indications and evidence pertaining to the use of heliox in pediatrics.

Upper airway obstruction

UAO occurs more frequently in children than in adults because their airways are considerably smaller in diameter. Etiologies include post-extubation subglottic edema, infections, and space-occupying lesions caused by neoplastic disease or pharyngeal abscesses.

Heliox may be a useful adjunct in reducing work of breathing (WOB), improving oxygenation, and preventing the need for intubation in children with UAO.

In a retrospective review of 42 patients between the ages of 1 week and 14 years who were treated with heliox for UAO, 73 percent of the children responded positively to treatment.5 Unfortunately, the criterion for WOB was largely anecdotal and limited the strength of this conclusion.

Interestingly, children with congenital anomalies in this group only had a 33-percent response rate. The authors felt the poor response in this subgroup was related to the nonpulmonary manifestations of their syndrome such as hypotonia.5

Two small studies have demonstrated the effectiveness of heliox in treating post-extubation stridor. In the first study, researchers reported a decrease in respiratory distress with alleviation of stridor. This prevented the need for reintubation in eight pediatric burn patients.6

A second study also reported a reduction in post-extubation stridor in 13 children with a trauma diagnosis.7 It concluded the use of heliox decreased respiratory distress scores and should be considered the preferred method of treatment in this patient population.7

Another common source of UAO affecting children between the ages of 6 months and 3 years is laryngotracheobronchitis, or croup. The most common croup syndrome is acute viral laryngotracheitis (viral croup), which causes subglottic inflammation when contracted. This results in airway narrowing and an acute onset of stridor.

A randomized double-blind trial that compared heliox to racemic epinephrine (standard croup therapy) in children with croup scores ³ 5 found no difference in croup scores, SpO2, respiratory rate, or heart rate between groups.8 The study concluded racemic epinephrine and heliox are equally effective in treating moderate to severe croup.8


Bronchiolitis is the inflammation of the bronchioles in infants under the age of 2 years. It’s characterized by airway obstruction from bronchiole wall edema, cellular debris, and excessive mucus. In most cases, care is supportive in nature, but heliox may be of some clinical benefit in more severe situations.

Researchers conducted a randomized double-blind controlled crossover study to determine the effects of heliox versus oxygen. Both were administered in 20-minute intervals to 13 randomized and five nonrandomized children with respiratory syncytial virus (RSV)-positive bronchiolitis.9

The five nonrandomized children were considered severely ill and received heliox to avoid intubation. Measures included clinical asthma score, respiratory rate, heart rate, and SpO2 at baseline and after each 20-minute treatment period. Clinical asthma scores decreased in all 18 patients during heliox administration.9

The most pronounced improvement in clinical asthma scores occurred in children with the greatest respiratory compromise. Researchers concluded the administration heliox improved the overall WOB in children with RSV-positive bronchiolitis.9

More recently, physicians observed no significant difference in the need for positive pressure ventilation in children with severe bronchiolitis receiving heliox compared with those receiving standard oxygen therapy.10 They also reported no differences in physiologic status such as clinical scores, oxygen requirement, PaCO2, or PICU length of stay.

Though the findings seem strong, there are several drawbacks to this particular study’s design. First, only 25 percent (39) of the 157 patients screened were randomized. Additionally, the group used a hood for gas administration, which would allow the helium to rise to the top and the oxygen to fall to the bottom where the children were actually breathing.

Another issue was the requirement of a relatively high level of oxygen, which some have defined as a heliox failure.11 With this in mind, the limitations should be considered when discussing the results of the study.

Pediatric asthma

The 2002 update for the guidelines for asthma diagnosis and management from the National Asthma Education and Prevention Program brought to light the benefits of heliox therapy for asthma exacerbation.12 Several randomized controlled trials have evaluated its effectiveness in pediatric asthma.

A double-blind randomized controlled trial assessed the effects of heliox on pulsus paradoxus, dyspnea index, and peak expiratory flow in 18 children with asthma.13 Ten children received the study gas (heliox) and eight received the control gas (oxygen).

Researchers collected data at baseline and in 15-minute intervals. At the first 15-minute measurement, the group found significant differences in pulsus paradoxus and dyspnea index.

The peak expiratory flow rates of 11 children (seven from the study group and four from the control group) were then measured while breathing heliox using a density-corrected flow meter. These children had a significant increase in the peak flow above their baseline measurement.

Consequently, both pulsus paradoxus and dyspnea index increased after heliox discontinuation. The study concluded using heliox relieves dyspnea and decreases the WOB in children with status asthmaticus.14

Other researchers compared heliox (70:30) and oxygen-driven continuous albuterol nebulization in 30 children who presented to an emergency department with moderate-to-severe asthma.14 Their study was the first prospective randomized single-blind study of its kind in children.

Investigators videorecorded the appearance and audiotaped the breath sounds for each study subject. A blinded investigator evaluated the audio-video data and assigned a pulmonary index (PI) score at eight time points for 240 minutes or until discharge.

The heliox group’s average PI was higher at baseline. The mean change in PI score for the heliox group was 6.67 compared with 3.33 in the oxygen group. The group also found the heliox group had more children discharged within 12 hours when compared to the oxygen group.

The investigators concluded continuously nebulized albuterol delivered by 70:30 heliox was associated with a greater degree of clinical improvement among moderately to severely ill children with asthma.14

But a 2006 study reported dissimilar results in a prospective blinded, randomized controlled trial of children with asthma.15 Physicians used a modified dyspnea index to evaluate the initial response to heliox-driven continuously nebulized albuterol at 10 and 20 minutes when compared to a 70:30 air/oxygen mixture.

No statistically significant differences were found regarding dyspnea index at 10 minutes or 20 minutes. There was no difference in admission rates as 12 subjects from the heliox group were admitted compared to 17 subjects from the oxygen group.

The physicians concluded heliox offered no clinical benefit over standard therapy in children with asthma.15

Heliox safety

The potential benefits of heliox have propagated the commercial development of helium-specific devices, and regulators, flow meters, and noninvasive heliox administration systems are commercially available. However, clinicians should examine several safety concerns.

One potential hazard regarding regulators pertains to the Compressed Gas Association 280 threaded regulator inlet and Diameter Index Safety System 1020/1180/1200 cylinder outlets. They’re the same for heliox and carbogen, a mixture of 95-percent oxygen and 5-percent carbon dioxide that’s frequently used during extracorporeal membrane oxygenation. For this reason, it’s paramount for the clinician to double check the tank label before administering any gas mixture.

To further decrease the risks of heliox administration, the oxygen concentration should be analyzed continuously and documented clearly.

This will ensure the patient receives the desired FiO2 and help prevent the delivery of a hypoxic gas mixture.

Blended heliox with no less than 20 percent oxygen always should be used, and 100-percent helium source gas never should be placed in a closed system. This helps eliminate the potential for delivering an oxygen-deficient gas mixture, which can result in anoxia.

Heliox flows through an orifice faster than oxygen. Using an oxygen flow meter to deliver heliox will result in higher flow rates than shown on the flow meter.

Heliox flow meters are commercially available, and the cost is roughly the same as standard oxygen flow meters. However, many departments choose to use oxygen flow meters instead.

When using an oxygen flow meter for heliox delivery, a correction factor must be applied.16 (See Table 3.) For example, an oxygen flow meter delivering an 80:20 heliox mixture at 10 Lpm actually is supplying a flow of 18 Lpm.

Helium-tight doesn’t equal airtight. Helium’s high diffusion rate allows for a small leak to become a large leak, thus greatly affecting gas consumption.

To minimize this consumption and decrease associated delivery costs, clinicians must ensure a helium-tight fit. To accomplish this, a system should have a tight-fitting mask such as a non-rebreather or other type of approved interface with a reservoir and/or an on-demand type delivery system.

It’s also important for the delivery system to meet the patient’s inspiratory flow demand. If the heliox flow is inadequate, the system will entrain ambient air and decrease the effectiveness of the gas.

Avoid jury-rigging

Unfortunately, heliox delivery systems are a frequent source of jury-rigging. Jury-rigging simply means using a device for purposes it’s not designed for, which adds unneeded risk and liability to patient care.

If a department chooses to use a jury-rigged or homemade heliox delivery system, the liability shifts from manufacturer to clinician. As Food and Drug Administration-approved heliox devices become more available, they should be integrated into clinical practice.

Homemade delivery systems are complex and take time to construct, but commercially available systems are less complicated. This permits greater staff comfort and provides a higher degree of patient safety.

While the initial investment in the proper equipment may be large, in the end it’s always cheaper than litigation.

Heliox is a potentially useful therapeutic adjunct for treating children with acute airway obstruction. Its low density, rapid onset, and extremely safe profile make it an excellent choice for children with increased WOB and a relatively low oxygen requirement. Heliox should be considered as a “therapeutic bridge” allowing time until other treatment regimens can take effect.


1. Barach AL. The use of helium in the treatment of asthma and obstructive lesions of the larynx and trachea. Ann Intern Med. 1935;9:739-65.

2. Lu TS, Ohmura A, Wong KC, Hodges MR. Helium-oxygen in the treatment of upper airway obstruction. Anesthesiology. 1976;45:678-80.

3. Kass JE. Heliox redux. Chest. 2003;123(3):673-6.

4. Myers TR. Use of heliox in children. Respir Care. 2006;51(6):619-31.

5. Grosz AH, Jacobs IN, Cho C, Schears GJ. Use of helium-oxygen mixtures to relieve upper airway obstruction in a pediatric population. Laryngoscope. 2001;111(9):1512-4.

6. Rodeberg DA, Easter AJ, Washam MA, Housinger TA, Greenhalgh DG, Warden GD. Use of a helium-oxygen mixture in the treatment of postextubation stridor in pediatric patients with burns. J Burn Care Rehabil. 1995;16(5):476-80.

7. Kemper KJ, Ritz RH, Benson MS, Bishop MS. Helium-oxygen mixture in the treatment of postextubation stridor in pediatric trauma patients. Crit Care Med. 1991;19(3):356-9.

8. Weber JE, Chudnofsky CR, Younger JG, Larkin GL, Boczar M, Wilkerson MD, et al. A randomized comparison of helium-oxygen mixture (heliox) and racemic epinephrine for the treatment of moderate to severe croup. Pediatrics. 2001;107(6):E96.

9. Hollman G, Shen G, Zeng L, Yngsdal-Krenz R, Perloff W, Zimmerman J, et al. Helium-oxygen improves clinical asthma scores in children with acute bronchiolitis. Crit Care Med. 1998;26(10):1731-6.

10. Liet Jm, Millotte B, Tucci M, Laflammme S, Hutchison J, Creery D, et al. Noninvasive therapy with helium-oxygen for severe bronchiolitis. J Pediatr. 2005;147(6):147:812-7.

11. DeNicola LK, Gayle MO, Blake KV. Drug therapy approaches in the treatment of acute severe asthma in hospitalised children. Paediatr Drugs. 2001;3(7):509-37.

12. National Asthma Education and Prevention Program. Expert panel report: guidelines for the diagnosis and management of asthma update on selected topics — 2002 [published erratum appears in J Allergy Clin Immunol. 2003;111(3):466]. J Allergy Clin Immunol. 2002;110(5 Suppl):S141-219.

13. Kudukis TM, Manthous CA, Schmidt GA, Hall JB, Wylam ME. Inhaled helium-oxygen revisited: effect of inhaled-oxygen during the treatment of status asthmaticus in children. J Pediatr. 1997;130(2):217-24.

14. Kim IK, Phrampus E, Venkataraman S, Pitetti R, Saville A, Corcoran T, et al. Helium/oxygen-driven albuterol nebulization in the treatment of children with moderate to severe asthma exacerbations: a randomized, controlled trial. Pediatrics. 2005;116(5):1127-33.

15. Rivera ML, Kim TY, Stewart GM, Minasyan L, Brown L. Albuterol nebulized in heliox in the initial ED treatment of pediatric asthma: a blinded, randomized controlled trial. Am J Emerg Med. 2006;24(1):38-42.

16. Fink JB. Opportunities and risks of using heliox in your clinical practice. Respir Care. 2006;51(6):651-60.

Bradley A. Kuch, BS, RRT-NPS, is a respiratory therapist in the department of critical care medicine/transport at Children’s Hospital of Pittsburgh.

A Primer on Helium and Heliox

Helium is a colorless, tasteless, nontoxic, and noncombustible element with a low molecular weight, high wave speed, high thermal conductivity, and low density.1 When combined with oxygen, it forms the gas mixture heliox.

In a heliox mixture, nitrogen is replaced with helium, which greatly reduces its density. Commercially, heliox is available in mixtures of 80 percent helium and 20 percent oxygen (80:20), 70 percent helium and 30 percent oxygen (70:30), and 60 percent helium and 40 percent oxygen (60:40).

It’s important to note that changing the concentration of heliox will alter the density of the gas mixture and decrease its clinical effectiveness. (See Table 2.)

Diffusion and wave speed

Helium’s low molecular weight allows rapid diffusion. If you think back to Respiratory Care 101, you’ll probably recall Graham’s Law: The rate of diffusion is inversely related to the square root of gas density. A high rate of diffusion allows for better distribution of tidal volume and carbon dioxide elimination.

Helium also exhibits high wave speed, which is the speed a wave travels through a gas-filled tube. Simply, maximum flow increases as gas density decreases. Helium’s high wave speed may be the reason heliox is beneficial in flow-limited diseases such as asthma and bronchiolitis.

Thermal conductivity

An important concept often overlooked is helium’s high thermal conductivity. That’s the measure of a substance’s capacity to conduct heat. Helium’s thermal conductivity is about six times greater than air.

Heat conductance is a major factor in skin heat loss. As a result, a patient’s body temperature will drop when surrounded by heliox. This always should be considered when delivering heliox to an infant via hood, as it may result in hypothermia.

High thermal conductivity also explains why helium affects the accuracy of hot-wire flow sensors used by some ventilators.

Density and flow patterns

Helium’s low density improves gas flow through high-resistance airways, and this is the cornerstone of most of its clinical benefits. For example, it’s about seven times lighter than atmospheric air and has been shown to decrease airway resistance by 50 percent to 75 percent.2

To grasp how a low-density gas affects airway resistance, review the physics of fluid flow. Actions of a fluid in motion are dependent on density and viscosity. There are three primary flow patterns: laminar, turbulent, and transitional.

Laminar flow is uniform, cylindrical layers of gas that’s viscosity and density dependent. It’s efficient as it varies directly with changes in pressure.

Turbulent flow, the opposite of laminar flow, is a muddled, inefficient movement of gas that forms irregular eddies throughout a tube. It’s density and viscosity dependent, and in the presence of turbulent flow, a low-density gas will decrease the pressure required to produce a given flow. This is beneficial in disease states with high airway resistance.

The third type of flow is transitional, a pattern where flow is neither fully laminar nor fully turbulent. The regions where this occurs are considered transitional zones. Heliox, with a lower density, is thought to work in these zones by changing turbulent flow into a more laminar pattern.

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–Bradley A. Kuch, BS, RRT-NPS