Theoretical validation of the respiratory benefits of helium-oxygen mixtures

doi:10.1016/0034-5687(94)00071-7

Respiration Physiology

Volume 99, Issue 1, January 1995, Pages 183-190

Respiration Physiolo...

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Abstract

A theoretical analysis of convective gas transport validates the clinically demonstrated advantage of using helium-oxygen mixtures in treating patients with respiratory problems. Previous studies have attributed that advantage to the ability of helium-oxygen to stay laminar at higher velocities than nitrogen-oxygen. The present work shows that helium-oxygen does not need to be laminar to provide higher flow rates and that its benefits persist under turbulent conditions. The analysis is applied to steady flow through the lungs and through a circular airway obstruction. A simplified model of the lungs gives pressure-flow relations that show a significant increase in oxygen flow rate when nitrogen is substituted by helium. A similar improvement is found for flow through an obstruction. For a given pressure difference across the lungs or across an obstruction, the turbulent flow rate of oxygen increases by approximately 50% when nitrogen is replaced by helium in a mixture containing 20% oxygen.

References (8)

E.H. Gluck et al.
Helium-oxygen mixtures in intubated patients with status asthmaticus and respiratory acidosis
Chest
(1990)
J.R. Houck et al.
Effect of helium concentration on experimental upper airway obstruction
Ann. Otol. Rhinol. Laryngol.
(1990)
T.J. Pedley et al.
Aerodynamic theory
R.A. Sauder et al.
Helium-oxygen and conventional mechanical ventilation in the treatment of large airway obstruction and respiratory failure in an infant
Southern Med. J.
(1991)

There are more references available in the full text version of this article.

Cited by (122)

Is helium beneficial in a pulmonary rehabilitation program for severe COPD?
2022, Revue des Maladies Respiratoires
L’hélium améliore les débits ventilatoires. Notre hypothèse d’une amélioration de l’endurance plus importante sous mélange Hélium-Oxygène (He-O2 : 80/20 %) dans le réentraînement à l’exercice des patients BPCO sévères, a été testée dans une étude randomisée en double aveugle.
Sur 53 patients randomisés en deux groupes, 45 ont été analysés : Hélium (n= 23) et air (n = 22). Les patients ont été évalués par spirométrie sous air et He-O2, épreuve d’effort incrémentale, épreuves d’endurance et test de marche. Tous ont effectué 15 séances de réentraînement sur cycloergomètre (air ou hélium à leur insu), dans le cadre d’un programme de réhabilitation respiratoire.
Il n’y a pas de différence significative du temps d’endurance entre les deux groupes (He : +52,5 sec, Air : +114 sec). L’amélioration de plus de 10 % du VEMS sous hélium définit un groupe de 20 patients répondeurs à l’hélium qui améliorent leur temps d’endurance médian de 135 sec contre 50 sec chez les non répondeurs (non significatif).
Chez les patients BPCO sévères, l’utilisation du mélange He-O2 n’apporte pas de gain en endurance. Les patients répondeurs à l’hélium ont une amélioration plus importante de leur endurance. L’amélioration du VEMS sous hélium devrait, à l’avenir être prise en compte.
Helium is known to reduce airflow limitation. Our hypothesis was that severe COPD patients undertaking exercise would show greater improvement in endurance under a heliox mixture (80/20%) than under air alone. This hypothesis was tested in a double-blinded, randomized study.
Out of the 53 patients included, 45 were randomly assigned to two groups : Heliox (n= 23) and Air (n= 22). Patients were assessed with spirometry under air and heliox, incremental exercise test, constant workload (80% Wmax) exercise test and weekly 6-minute walk test. The two groups went through fifteen 30-minute retraining sessions in the overall framework of an identical pulmonary rehabilitation program.
There was no significant difference in endurance improvement (Heliox : +52.5 sec, Air: + 114 sec, median value). FEV1 improvement under heliox exceeding 10% identified a group of 20 patients as “helium responders”, who improved their endurance time by a median of 135 sec compared to 50 sec for the “non-responders” (non-significant difference).
In patients with severe COPD, use of Heliox in exercise retraining did not produce significantly improved endurance. On the other hand, “helium responders” showed more FEV1 improvement than non-responders. Improved FEV1 under heliox should therefore be used in future studies as an inclusion criterion.
Does heliox administered by low-flow nasal cannula improve respiratory distress in infants with respiratory syncytial virus acute bronchiolitis? A randomized controlled trial
2019, Anales de Pediatria
El objetivo del estudio fue evaluar si el uso de heliox (79:21) administrado vía cánula nasal de bajo flujo mejora el trabajo respiratorio en lactantes con bronquiolitis aguda causada por virus respiratorio sincitial.
Se realizó un estudio prospectivo aleatorizado controlado. Todos los pacientes que cumplieron los criterios de inclusión se asignaron al azar a tratamiento con heliox (79:21) o con aire, administrados mediante cánula nasal a razón de 2 L/min durante un período ininterrumpido de 24 h. Se realizaron medidas basales, a las 2 h de iniciar el tratamiento y al completarse las 24 h.
Se incluyeron 104 pacientes en el estudio. No se observaron diferencias significativas en la puntuación de la M-WCAS entre los dos grupos a las 2 h (4,3 vs. 4,1; p = 0,78) o al completarse las 24 h (4,2 vs. 4,3; p = 0,89). No hubo diferencias en las proporciones de participantes que progresaron a ventilación mecánica, CPAP-n u oxigenoterapia administrada mediante cánula nasal (RR: 1,0, 0,86 y 0,89; p = 1,0, 0,77 y 0,73). No hubo una reducción significativa en la duración de tratamiento, de 2,42 días en el grupo tratado con heliox y de 2,79 días en el grupo tratado con aire (p = 0,65). Tampoco hubo diferencias significativas entre los dos grupos bajo estudio en la saturación de oxígeno, PaO₂ o PaCO₂ a las 2 y a las 24 h de tratamiento.
Nuestros datos no mostraron ningún efecto beneficioso del heliox a una concentración de 79:21 administrado vía cánula nasal de bajo flujo en cuanto a la mejoría de la dificultad respiratoria en lactantes con bronquiolitis aguda por VRS.
The aim of our study is to evaluate whether the use of heliox (79:21) delivered through a low flow nasal cannula would improve respiratory distress in infants with acute bronchiolitis caused by respiratory syncytial virus.
We have conducted a prospective randomized controlled study. All patients fulfilled inclusion criteria were randomized to either heliox (79:21) or air via NC at 2 L/min for a continuous 24 hours. Measurements were taken at baseline, after 2 hours and at the end of the 24 hours.
We have included 104 patients into our study. The MCA-S did not show any significant difference between the two groups after 2 hours 4.3 vs. 4.1 (P =.78), or at 24 hours after 4.2 vs. 4.3 (P =.89). No difference was found in the proportion of participants progressed to MV, n-CPAP or oxygen via nasal cannula (RR 1.0, 0.86 and 0.89) (P= 1.0, .77 and .73). There was no notable reduction in length of treatment in Heliox group 2.42 days vs. 2.79 days in air group P =.65. The in oxygen saturation, PaO₂, and PaCO₂ did not to have any statistical difference between the two studied groups after 2 hours and 24 hours of treatment.
Our data showed absence of any beneficial effect of heliox in a concentration (79:21) delivered through low flow nasal cannula in terms of respiratory distress improvement in infants with RSV acute bronchiolitis.
Heliox delivered by high flow nasal cannula improves oxygenation in infants with respiratory syncytial virus acute bronchiolitis
2018, Jornal de Pediatria
The objective of this study is to evaluate the hypothesis that use of heliox would result in improvement of gas exchange when used with high flow nasal cannula in infants with RSV acute bronchiolitis.
All patients that met the inclusion criteria were randomized to either heliox (70:30) or air–oxygen mixture 30% via high flow nasal cannula at 8 L/min for a continuous 24 h. Measurements were taken at baseline, after 2 h, and at the end of the 24 h.
This prospective study included 48 patients. After 2 h of treatment with heliox, the oxygen saturation and PaO₂ significantly improved when compared with the air–oxygen group, 98.3% vs. 92.9%, 62.0 mmHg vs. 43.6 mmHg (p = 0.04 and 0.01), respectively. Furthermore, PaO₂/FiO₂ ratio was significantly higher in the heliox group when compared with the air–oxygen group, 206.7 vs. 145.3. Nevertheless, CO₂ showed better elimination when heliox was used, without significance. MWCA score dropped significantly in the heliox group, 2.2 points vs. 4.0 points in air–oxygen (p = 0.04), 2 h after starting the therapy.
Transient improvement of oxygenation in infants with RSV acute bronchiolitis during the initial phase of the therapy is associated with heliox when provided with HFNC, may provide a precious time for other therapeutic agents to work or for the disease to resolve naturally, avoiding other aggressive interventions.
O objetivo deste estudo é avaliar a hipótese de que o uso da mistura heliox resultaria em melhora da troca gasosa quando usado com cânula nasal de alto fluxo em crianças com bronquiolite aguda por VSR.
Todos os pacientes que atenderam aos critérios de inclusão foram randomizados para receber a mistura heliox (70:30) ou a mistura ar/oxigênio a 30% por meio da cânula nasal de alto fluxo a 8 L/min por 24 horas contínuas. As medições foram feitas no início, depois de 2 horas e ao fim de 24 horas.
Realizamos um estudo prospectivo em que foram incluídos 48 pacientes. Após 2 horas de tratamento com a mistura heliox, a saturação de oxigênio e a PaO₂ apresentaram melhora significativa em comparação ao grupo da mistura ar/oxigênio: 98,3% em comparação a 92,9%, 62,0 mmHg em comparação a 43,6 mmHg (p = 0,04 e 0,01), respectivamente. Além disso, a relação PaO₂/FiO₂ era significativamente mais alta no grupo da mistura heliox que no grupo da mistura ar/oxigênio, 2067 em comparação a 1453. Contudo, o CO₂ apresentou melhor eliminação quando a mistura heliox foi utilizada, sem relevância. O Escore MWCA caiu significativamente no grupo da mistura heliox, 2,2 pontos em comparação a 4,0 pontos da mistura ar/oxigênio (p = 0,04) 2 horas após o início da terapia.
A breve melhora da oxigenação em crianças com bronquiolite aguda por VSR na fase inicial da terapia está associada à mistura heliox quando administrada pela CNAF e poderá fornecer um tempo precioso para outros agentes terapêuticos funcionarem ou para a própria doença se curar naturalmente e evitar outras intervenções agressivas.
Management of Dyspnea and Central Airway Obstruction in Patients With Malignancy
2017, Handbook of Supportive and Palliative Radiation Oncology
Dyspnea is a subjective sensation of breathlessness which can be exacerbated by psychological distress. Dyspnea arises from complex multisystem processes, making it challenging to diagnose and control effectively. However, immediate evaluation and maintenance of airway is required in order to allow for more time to identify potentially reversible causes. When central airway obstruction (CAO) is identified, interventional procedures to manage CAO are palliative, but these interventions can significantly reduce dyspnea, improve functional status, reduce postobstructive infections, enhance quality of life, and enable better radiographic evaluation for staging. Because interventions are palliative, one should carefully assess the risk of any procedure with the potential for palliative benefit.
Defining hyperinflation as 'dynamic': Moving toward the slope
2013, Respiratory Medicine
Measuring the severity of dynamic hyperinflation is a useful clinical approach to assess the effect of therapeutic interventions and explain their impact on exercise tolerance. Dynamic hyperinflation is typically quantified by the change in end expiratory lung volume from rest to the end of exercise. The result may be inconsistent with disease severity and does not clearly explain how exercise tolerance improves with therapy. Using a re-examination of selected studies, we suggest an operational definition of dynamic hyperinflation using the slope derived from serial measures of inspiratory capacity expressed as a linear function of ventilation that clearly differentiates whether therapies affect static or dynamic hyperinflation or affect lung volume only as a consequence of reducing ventilation. With this approach, the magnitude of the result is consistent with disease severity and is a more reliable outcome as it uses serial measures rather than a single time point estimate. The therapies re-evaluated are breathing helium or hyperoxic gas mixtures, bronchodilation and exercise training. A clear definition of dynamic hyperinflation will assist clinicians in assessing the impact of therapeutic interventions.
Respiratory Syncytial Virus Bronchiolitis in Children
2012, Critical Care Nursing Clinics of North America
Citation Excerpt :
Heliox, an inert gas composed of helium and oxygen, is a popular therapeutic adjunct in the care of severe bronchiolitis. As a low-density gas, heliox decreases the resistance of gas flow and reduces the work of breathing.89,91 In a meta-analysis of patients with bronchiolitis admitted to the PICU, Liet and colleagues92 (2010) found that heliox improved respiratory status after 1 hour of therapy.

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Research articleTheoretical validation of the respiratory benefits of helium-oxygen mixtures

Abstract

Chest

Effect of helium concentration on experimental upper airway obstruction

Ann. Otol. Rhinol. Laryngol.

Aerodynamic theory

Helium-oxygen and conventional mechanical ventilation in the treatment of large airway obstruction and respiratory failure in an infant

Southern Med. J.

Research article
Theoretical validation of the respiratory benefits of helium-oxygen mixtures