Effect of Heliox Breathing on Dynamic Hyperinflation in COPD Patients

doi:10.1378/chest.125.6.2075

Chest

Volume 125, Issue 6, June 2004, Pages 2075-2082

https://doi.org/10.1378/chest.125.6.2075 Get rights and content

Background and objective

Patients with COPD exhibit increased inspiratory work and dyspnea due to dynamic hyperinflation caused by expiratory flow limitation. Helium-oxygen mixtures (ie, heliox) have been used in treating these patients on the assumption that, by lowering airway resistance, they might be beneficial.

Methods

In 22 patients with COPD, the presence of expiratory flow limitation was assessed with patients in the sitting and supine positions using the negative expiratory pressure technique, and the effects of heliox (80% He, 20% O2) on breathing pattern, expiratory flow limitation, and dynamic hyperinflation, evaluated from the change in inspiratory capacity (IC), were measured at rest and were compared with those due to inhaled salbutamol.

Results

During air breathing, 13 patients experienced flow limitation while in the sitting position and 18 experienced flow limitation while in the supine position. Neither heliox nor salbutamol therapy changed the breathing pattern in any of the patients, regardless of posture and the presence or absence of expiratory flow limitation. However, in both positions IC increased significantly in most flow-limited patients after bronchodilator administration, but not after heliox administration.

Conclusions

Since heliox had no effect on dynamic hyperinflation, the use of this gas mixture, which is costly and cumbersome, does not appear to be beneficial in stable patients with COPD breathing at rest.

Section snippets

MATERIALS AND METHODS

Twenty-two stable COPD patients (one woman) with a mean (± SE) age of 71 ± 1 years were studied. Patients had no other cardiopulmonary diseases, and had not experienced an upper respiratory tract infection during the previous month. No patient was being treated with oral β₂-agonists, theophylline, or systemic corticosteroids, or had received inhaled short-acting β₂-agonistic or anticholinergic drugs for 8 h or long-acting β₂-agonists for 24 h before the study. The study was approved by the

RESULTS

Table 1 shows the anthropometric characteristics and baseline lung function data of seated patients, who were stratified according to the presence or absence of expiratory flow limitation while sitting. Only FEV₁, FEV₁/FVC ratio, and the midexpiratory phase of maximal mean expiratory flow were significantly lower in flow-limited patients. Among all of the respiratory variables studied, the only significant correlation of MRC score was with the IC percent predicted in flow-limited patients (r =

DISCUSSION

Our main findings are that in all COPD patients who were flow-limited while breathing air at rest, heliox had no effect on dynamic hyperinflation, independent of posture, while, in the same flow-limited patients, salbutamol significantly increased IC in both the sitting and the supine position.

In the present COPD population, there was a high prevalence (59%) of flow limitation during air breathing while in the sitting position. There are no previous reports on the correlation of IC and FEV₁/FVC

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Cited by (37)

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.
Plethysmographic assessment of tidal expiratory flow limitation
2022, Respiratory Physiology and Neurobiology
Citation Excerpt :
Indeed, markedly higher Rexp/Rins and R2exp/Rins values must occur in the presence of tEFL, as it causes a selective increase of Rexp with respect to Rins, a discrepancy that is enhanced by the fact that the plethysmographic software provides the peak rather than the average values of intra-breath Rexp and Rins, and that in tEFL patients the width of the Palv-V̇ loop is markedly more pronounced in expiration than inspiration. The differences of routine spirometric and plethysmographic variables between tEFL and non-tEFL patients before bronchodilator administration (Table 1) as well as those caused by bronchodilator administration (Table 2) are in good agreement with the corresponding observations reported in previous studies (Koulouris et al., 1995; Eltayara et al., 1996; Diaz et al., 2001; Pecchiari et al., 2004; D’Angelo et al., 2009). Indeed, tEFL patients were characterized by higher ITGV, RV and airway resistance, hence lower IC and FEV1, as well as by a significant decrease of ITGV and RV with bronchodilator administration, which was not shared by non-tEFL patients.
Chronic obstructive pulmonary disease (COPD) patients often experience tidal expiratory flow-limitation (tEFL), a condition causing respiratory and cardiovascular detrimental effects. As the appearance of tEFL should increase expiratory (Rexp) relative to inspiratory (Rins) resistance, we hypothesized that Rexp/Rins can be used to detect tEFL.
Rexp/Rins was measured with a commercial plethysmograph in 109 healthy subjects and, before and after bronchodilation (BD), in 64 COPD patients, 36 with and 28 without tEFL according to the NEP technique.
Before BD, the median (interquartile range) of Rexp/Rins was significantly greater (P < 0.001) in COPD patients with tEFL (2.47(3.06;7.07)) than in COPD patients without tEFL (1.63(1.44;1.82)) and in healthy subjects (1.52(1.35;1.62)). In COPD patients Rexp/Rins above 1.98 predicted the presence of tEFL with 96 % specificity and 92 % sensitivity, Rexp²/Rins performing even better. After BD the predictive ability of Rexp/Rins slightly declined, but remained elevated.
The non-invasive measurement of Rexp/Rins is an easy, inexpensive, routinely usable method to detect tEFL in spontaneously breathing COPD subjects.
Contrasting breathing retraining and helium-oxygen during pulmonary rehabilitation in COPD: A randomized clinical trial
2014, Respiratory Medicine
Breathing-retraining and helium–oxygen (heliox) have been used to improve exercise tolerance in COPD. We hypothesized that, in patients with COPD, exercise duration after exercise-training plus breathing-retraining and oxygen would be longer than after exercise-training plus heliox or after exercise-training plus oxygen alone. We also explored the short-term maintenance of gains in exercise duration after using each technique.
Of 192 COPD patients recruited, 103 were randomly assigned to exercise-training plus heliox (n = 33), exercise-training plus breathing-retraining and oxygen (n = 35) and exercise-training and oxygen (n = 35). FiO₂ was 0.30 during testing and training in all groups. Patients exercised on a treadmill thrice-weekly for eight weeks. Before, at completion of training, and six-weeks later, patients underwent constant-load treadmill testing.
At completion of training, improvements in exercise duration in the heliox and breathing-retraining groups were not significantly different. Compared to the exercise-training plus oxygen group, exercise duration improved more in the breathing-retraining group (P = 0.008) but not in the heliox group (P = 0.142). Hyperinflation was reduced with breathing-retraining plus oxygen compared to the other two groups. Six-weeks later, improvements in exercise duration were still greater with breathing-retraining than with exercise-training (P = 0.015). In contrast, improvements in exercise duration with heliox did not differ from those in the other two groups.
In moderate-to-severe COPD, exercise-training combined with either heliox or with breathing-retraining yielded not significantly different improvements in exercise duration – with only the latter being superior to exercise-training. Six-weeks after training, these improvements were still greater after exercise-training plus breathing-retraining than after exercise-training.
ClinicalTrials.gov; No.: NCT00123422.
Helium:oxygen versus air:Oxygen noninvasive positive-pressure ventilation in patients exposed to sulfur mustard
2011, Heart and Lung: Journal of Acute and Critical Care
Exposure to sulfur mustard (SM) causes a variety of respiratory symptoms, such as chronic bronchitis and constrictive bronchiolitis. This study assessed the effectiveness of noninvasive positive-pressure ventilation, adjunct with 79:21 helium:oxygen instead of 79:21 air:oxygen, in 24 patients with a previous exposure to SM presenting with acute respiratory failure. Both air:oxygen and helium:oxygen significantly decreased systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse rate, respiratory rate, dyspnea, and increased oxygen saturation (P values: .007, .029, .002, <.001, <.001, <.001, and .002 for air:oxygen, respectively, and <.001, .020, .001, <.001, <.001, <.001, and .002, for helium:oxygen, respectively). Moreover, helium:oxygen more potently improved systolic pressure, mean arterial pressure, pulse rate, respiratory rate, and dyspnea (P values: .012, .048, <.001, <.001, and .012, respectively). The results of our study support the benefit of using helium:oxygen adjunct with noninvasive positive-pressure ventilation in patients exposed to SM with acute respiratory decompensation.
Contrasting pressure-support ventilation and helium-oxygen during exercise in severe COPD
2011, Respiratory Medicine
Citation Excerpt :
These increases prevent dynamic airway closure during exhalation32). A greater maximal exhalation flow for a given lung volume will allow patients to sustain the same ventilation before and after administration of helium–oxygen but with a lower end-expiratory lung volume under the latter condition.33 The capacity to maintain the same ventilation with a lower end-expiratory lung volume with helium–oxygen can take place as long as expiratory flow-limitation is located in the central airways.33
Helium–oxygen mixtures and pressure-support ventilation have been used to unload the respiratory muscles and increase exercise tolerance in COPD. Considering the different characteristics of these techniques, we hypothesized that helium–oxygen would be more effective in reducing exercise-induced dynamic hyperinflation than pressure-support. We also hypothesized that patients would experience greater increases in respiratory rate and minute ventilation with helium–oxygen than with pressure-support. The hypotheses were tested in ten patients with severe COPD (FEV₁ = 28 ± 3% predicted [mean ± SE]) during constant-load cycling (80% maximal workrate) while breathing 30% oxygen-alone, helium–oxygen, and pressure-support in randomized order. As hypothesized, helium–oxygen had greater impact on dynamic hyperinflation than did pressure-support (end-exercise; p = 0.03). For the most part of exercise, respiratory rate and minute ventilation were greater with helium–oxygen than with pressure-support (p ≤ 0.008). During the initial phases of exercise, helium–oxygen caused less rib-cage muscle recruitment than did pressure-support (p < 0.03), and after the start of exercise it caused greater reduction in inspiratory reserve volume (p ≤ 0.02). Despite these different responses, helium–oxygen and pressure-support caused similar increases in exercise duration (oxygen-alone: 6.9 ± 0.8 min; helium–oxygen: 10.7 ± 1.4 min; pressure-support: 11.2 ± 1.6 min; p = 0.003) and similar decreases in inspiratory effort (esophageal pressure-time product), respiratory drive, pulmonary resistance, dyspnea and leg effort (p < 0.03). In conclusion, helium–oxygen reduced exercise-induced dynamic hyperinflation by improving the relationship between hyperinflation and minute ventilation. In contrast, pressure-support reduced hyperinflation solely as a result of lowering ventilation. Helium–oxygen was more effective in reducing exercise-induced dynamic hyperinflation in severe COPD, and was associated with greater increases in respiratory rate and minute ventilation than pressure-support.
Expiratory flow-limitation and heliox breathing in resting and exercising COPD patients
2009, Respiratory Physiology and Neurobiology
In 26 stable patients with chronic obstructive pulmonary disease, tidal expiratory flow-limitation (TEFL), inspiratory capacity, breathing pattern and dyspnea sensation were assessed during air and heliox (20% O₂ in He) breathing at rest and during exercise up to 2/3 maximal work rate. Breathing air, the 13 patients with TEFL at rest remained flow-limited also during exercise, while 7 of the non-flow-limited patients became flow-limited; tidal volume increased more in non-flow-limited patients, whereas inspiratory capacity decreased in flow-limited and increased in the non-flow-limited patients. Heliox did not abolish flow-limitation, had no effect on breathing pattern, reduced exercise dynamic hyperinflation in 25% of the flow-limited patients, depending on the degree of the dynamic hyperinflation on air, and lessened dyspnea sensation in all patients. Hence, the presence of TEFL has no systematic effects on the respiratory response to heliox, and the heliox-induced decrease of exercise dyspnea is not mainly due to changes in dynamic hyperinflation or TEFL.

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This study was supported by Ministero dell'Istruzione, dell'Università e della Ricerca Scientifica (MIUR), Rome, Italy.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: [email protected]).

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Chest

Clinical InvestigationsAirtrappingEffect of Heliox Breathing on Dynamic Hyperinflation in COPD Patients

Background and objective

Methods

Results

Conclusions

Section snippets

MATERIALS AND METHODS

RESULTS

DISCUSSION

Chest

Statics of the respiratory system

Relationship between chronic dyspnea and expiratory flow limitation in patients with chronic obstructive pulmonary disease

Am J Respir Crit Care Med

Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest

Eur Respir J

A simple method to detect expiratory flow limitation during spontaneous breathing

Eur Respir J

Effect of salbutamol on dynamic hyperinflation in chronic obstructive pulmonary disease patients

Eur Respir J

Spirometric correlates of improvement in exercise performance after anticholinergic therapy in chronic obstructive pulmonary disease

Am J Respir Crit Care Med

Inhaled bronchodilators reduce dynamic hyperinflation during exercise in patients with chronic obstructive pulmonary disease

Am J Respir Crit Care Med

Volume effect and exertional dyspnoea after bronchodilator in COPD patients with and without expiratory flow limitation at rest

Thorax

The use of helium in the treatment of asthma and obstructive lesions in the larynx and trachea

Ann Intern Med

Gas flow and mixing in the airways

The effect of helium and oxygen mixtures on pulmonary resistances in emphysema

Am Rev Respir Dis

Impedance measurement during air and helium-oxygen breathing before and after salbutamol

Clin Exp Pharmacol Physiol

Density dependence of maximal expiratory flow in chronic obstructive pulmonary disease

Am Rev Respir Dis

Heliox in chronic obstructive pulmonary disease: time to lighten up?

Crit Care Med

Clinical Investigations
Airtrapping
Effect of Heliox Breathing on Dynamic Hyperinflation in COPD Patients