heliox therapy in bronchiolitis

Heliox Therapy in Bronchiolitis: Phase III MulticenterDouble-Blind Randomized Controlled Trial

WHATS KNOWN ON THIS SUBJECT: Bronchiolitis, a leading causeof infant hospitalization, has few proven treatments. A few smallstudies have reported the benecial effects of a mixture of 21%oxygen + 79% helium (Heliox). The 2010 Cochrane Review concludedthat additional large randomized controlled trials were needed todetermine the therapeutic role of Heliox in bronchiolitis.

WHAT THIS STUDY ADDS: The Bronchiolitis Randomized ControlledTrial Emergency-Assisted Therapy with HelioxAn Evaluation(BREATHE) trial is the largest multicenter randomized controlledtrial to date to investigate the efcacy of Heliox in acutebronchiolitis. The delivery method for Heliox therapy was found tobe crucial to its efcacy.

abstractBACKGROUND AND OBJECTIVE: Supportive care remains the mainstayof therapy in bronchiolitis. Earlier studies suggest that helium-oxygentherapy may be benecial, but evidence is limited. We aimed to compareefcacy of 2 treatment gases, Heliox and Airox (21% oxygen 1 79%helium or nitrogen, respectively), on length of hospital treatment forbronchiolitis.

METHODS: This was a multicenter randomized blinded controlled trial of319 bronchiolitic infant subjects randomly assigned to either gas; 281 sub-jects completed the study (140 Heliox, 141 Airox), whose data was ana-lyzed. Treatment was delivered via facemask (nasal cannula, if thefacemask intolerant) 6 continuous positive airway pressure (CPAP).Severe bronchiolitics received CPAP from the start. Primary end pointwas length of treatment (LoT) required to alleviate hypoxia and respira-tory distress. Secondary end-points were proportion of subjects needingCPAP; CPAP (LoT); and change in respiratory distress score.

RESULTS: Analysis by intention to treat (all subjects); median LoT (inter-quartile range, days): Heliox 1.90 (1.083.17), Airox 1.87 (1.113.34), P =.41. Facemask tolerant subgroup: Heliox 1.46 (0.851.95), Airox 2.01 (0.932.86), P = .03. Nasal cannula subgroup: Heliox 2.51 (1.214.32), Airox 2.81(1.454.78), P = .53. Subgroup started on CPAP: Heliox 1.55 (1.382.01),Airox 2.26 (1.842.73), P = .02. Proportion of subjects needing CPAP:Heliox 17%, Airox 19%, O.R. 0.87 (0.471.60), P = .76. Heliox reduced re-spiratory distress score after 8 hours (mixed models estimate, 20.1298;P , .001). The effect was greater for facemask compared with nasalcannula (mixed models estimate, 0.093; P = .04).

CONCLUSIONS: Heliox therapy does not reduce LoT unless given via a tight-tting facemask or CPAP. Nasal cannula heliox therapy is ineffective.Pediatrics 2013;131:661669

AUTHORS: Mina M. Chowdhury, MB, ChB,a Sheila A.McKenzie, FRCP,b Christopher C. Pearson, FRACP,c SiobhanCarr, FRCPCH,b Caroline Pao, MRCP,b Arvind R. Shah,FRCPCH,c Elizabeth Reus, MSc,a Joseph Eliahoo, PhD,e

Fabiana Gordon, PhD,e Hubert Bland, MB, ChB,f and ParvizHabibi, PhD, FRCP, FRCPCHa

aDepartment of Pediatrics, Wright Fleming Institute, ImperialCollege, London, United Kingdom; bDepartment of Pediatrics,Royal London Hospital Whitechapel, London, United Kingdom;cDepartment of Pediatrics, Womens and Childrens Hospital,North Adelaide, Australia; dDepartment of Pediatrics, NorthMiddlesex University Hospital, London, United Kingdom;eStatistical Advisory Service, Imperial College, London, UnitedKingdom; and fSurrey Clinical Research Centre, University ofSurrey, Guildford, United Kingdom

KEY WORDSrandomized controlled trial, heliox, bronchiolitis

ABBREVIATIONSAiroxmixture of 21% oxygen + 79% nitrogenBREATHEBronchiolitis Randomized Controlled Trial Emergency-Assisted Therapy with HelioxAn EvaluationCPAPcontinuous positive airway pressureFiO2fraction of inspired oxygenFMfacemaskHelioxmixture of 21% oxygen + 79% heliumLoTlength of treatmentNCnasal cannulaRCTrandomized controlled trialRSVrespiratory syncytial virusSpO2percutaneous oxygen saturation

Dr Chowdhury and Dr Habibi designed the study and wrote thetrial protocol and manuscript; Dr McKenzie, Dr Bland, Dr Carr,Dr Pao, Dr Shah, and Dr Pearson contributed to the study designand writing of manuscript; Dr Habibi was the chief investigator;Dr Chowdhury was the trial coordinating investigator; Dr McKenzie,Dr Carr, Dr Pao, Dr Shah, and Dr Pearson were principal inves-tigators at collaborating centers; Dr Habibi, Dr Chowdhury, andMs Reus coordinated study conduct and data collection at thecenters and played a major role in supervision of the trialnurses involved in recruitment; and Dr Eliahoo and Dr Gordonperformed the statistical analyses and contributed to thewriting and approval of the nal manuscript.

This trial has been registered at http://www.controlled-trials.com/ISRCTN18238432

www.pediatrics.org/cgi/doi/10.1542/peds.2012-1317

doi:10.1542/peds.2012-1317

Accepted for publication Dec 18, 2012

Address correspondence to Parviz Habibi, PhD, FRCP, FRCPCH,Reader and Consultant in Pediatric Intensive Care andRespiratory Medicine, Wright Fleming Institute, Imperial College,Norfolk Place, London W2 1PG, United Kingdom. E-mail: [email protected]

(Continued on last page)

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Acute viral bronchiolitis is a leadingcause of infant hospitalization, witha rising incidence and health-economicburden in developed countries.13 Inthe United States, 75 000 respiratorysyncytial virus (RSV)-positive bronchio-litic infants are hospitalized each year.4,5

Stang et al3 estimated the annual costburden of this to be between US$365and $585 million. Although there aremany treatments, few have a strongevidence base or have demonstrateda reduced length of hospital stay orneed for respiratory support,6 with ox-ygen being the mainstay of therapy. Amixture of 21% oxygen + 79% helium(Heliox) is lighter than air or oxygen,promoting laminar ow in areas ofturbulence or airway narrowing andthus may improve respiratory distressand wheezing.7 Heliox also reduces re-spiratory system resistance, hasa higher binary diffusion coefcient forCO2 and O2 and therefore may enhancealveolar gas exchange and lung re-cruitment, and is an inert gas with anexcellent safety prole.810 Heliox maytherefore be a useful therapy in bron-chiolitis that is associated with smallairway inammation causing increasedrespiratory system resistance and in-creased work of breathing. Since 1996when Paret et al11 successfully treateda bronchiolitic infant in respiratoryfailure with Heliox, 9 studies (combinedtotal of 172 infants) have investigatedHeliox treatment in bronchiolitis.7,9,1218

Six of these studies7,9,13,1618 reportedvarious clinical benets, including im-provement of hypercapnea and re-spiratory distress. These studies hadsmall sample sizes, used different de-livery methods for Heliox, and were notalways blinded, and only 1 study16

assessed the effect of Heliox on length oftreatment (LoT) or hospital stay. Fur-thermore, regardless of clinical efcacy,heliox must be cost-effective. The cost ofa single bed day on a pediatric ward is$1947.19,20 Even reducing the hospitalLoT by 0.5 dayswould save $974,which is

equivalent to 14 cylinders of Heliox ata cost of $70 each.21 In our experience,only 3 to 5 cylinders per day are con-sumed during Heliox therapy, thus sup-porting our hypothesis that Heliox maybe cost-effective if it reduces duration ofhospital treatment. The 2010 CochraneReview concluded that additional largerandomized controlled trials (RCTs)were needed to investigate the deliverysystem for Heliox and determine itstherapeutic role in bronchiolitis.22 Wetherefore report the largest phase III RCT,called Bronchiolitis Randomized Con-trolled Trial Emergency-Assisted Therapywith HelioxAn Evaluation (BREATHE).Results of this work have been pre-viously published as an abstract.23

METHODS

Setting

A prospective, double-blind RCT wascarried out in the bronchiolitis seasonsduring 2005 to 2008 across 4 centers inthe United Kingdom and Australia.

Participants

Pediatricians in the emergency de-partments or pediatric wards of par-ticipating hospitals, independent ofthe BREATHE study, assessed infants(or 12-month corrected age if pre-mature). They clinically determined ifthe infants had a diagnosis of bron-chiolitis (history of upper respiratorytract infection followed by wheezing,coughing, breathing difculty, or chestcrackles on auscultation) and if theyneeded hospitalization for respiratorydistress or hypoxia (percutaneousoxygen saturation [SpO2] , 93% inroom air). Exclusion criteria were asfollows: imminent intubation; SpO2 ,93% despite 15 L/minute O2 via non-rebreathing facemask (FM); trache-ostomy; participation in another studyin the previous 4 weeks; salbutamol,epinephrine, or ipratropium therapywithin 1 hour or systemic steroidswithin 4 hours of entry into the study;

and bronchiolitis readmission within24 hours of exit from BREATHE. Anindependent data committee moni-tored safe conduct throughout thestudy. The trial was registered in-ternationally and had independentethics committee approval.

Interventions

Heliox or a mixture of 21% oxygen + 79%nitrogen (Airox), labeled as gas A or B,was the treatment or control in-tervention with additional oxygen ti-trated via Y-connection tubing, resultingin 2 gas mixes: A or B 6 additional ox-ygen. Gas delivery was by a tight-tting3-valve, nonrebreathing facemask (FM;1192; Intersurgical) or a nasal cannula(NC; BC 2745-20; Fisher & PaykelHealthcare) if the subject was FM in-tolerant. Gas A or B drove the continuouspositive airway pressure (CPAP) device(EME infant ow driver; CareFusion).

Outcome Measures

The primary end point was the total LoTto alleviate hypoxia (SpO2 $ 93% inroom air) and respiratory distress(minimal work of breathing). LoT wascalculated from the start to successfulstop of the trial gas, as dened by clin-ical stability (minimal work of breathingand SpO2 $ 93%) for 1 hour breathingroom air. Minimal work of breathingwas qualied as having a normal re-spiratory rate, no cyanosis, no nasalaring, no tracheal tug or grunting, nohead bobbing, and no use of accessorymuscles except for mild intercostalrecessions. Secondary end points wereproportion of each treatment groupneeding CPAP and the change in re-spiratory distress over time measuredby the Modied Woods Clinical AsthmaScore (Table 1). We used a scoring toolto assess change in respiratory distressover time, similar to that used in pre-vious heliox studies.13,16 The scoring toolwas a modied version of the originalWoods Clinical Asthma Score.24

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At each assessment period, the type ofdelivery (FM or NC) and FM tolerancewas prospectively recorded on the trialclinical report forms to allow analysisof LoT in the FM and NC subgroups. Wealso recorded the duration of CPAPtherapy (CPAP LoT) in a group of severebronchiolitic subjects who were com-menced on CPAP from the beginning oftreatment to compare the impact ofHeliox versus Airox on duration of CPAP.

Management of bronchiolitis was stan-dardized to a strict protocol across trialcenters: gas A or B6 oxygen humidiedvia MR850 (Fisher & Paykel Healthcare),minimal handling, attention to hydrationstatus, and careful airway toilet/suction.Intravenous uids were preferred overnasogastric feeding in subjects with se-vere respiratory distress. Bronchodilator,epinephrine, or steroid use constitutedtrial protocol violations. A team ofBREATHE trial nurses ensured adherenceto these standards and the trial protocol.

The BREATHE treatment protocol isshown in Fig 1. Subjects had FM therapyfor 30 minutes. If they were FM in-tolerant, the NC protocol was used. Ifsubjects were hypoxic despite FM/NC,the CPAP protocol was started. FM tol-erance was recorded at each assess-ment period, and FM tolerant wasstrictly dened as mask on all of thetime except for oronasal suction andfeeding. FM intolerance was dened asincreasing agitation, distress, shakinghead from side to side, and pulling theFM off the face for 30 minutes. NC was

started in subjects who remained FMintolerant for 30 minutes. The optimumow rate for trial gas was based on ti-tration against oxygen to achieve SpO2$ 93% using the minimum ow of ad-ditional oxygen. For FM therapy, themaximum combined ow rate (gas A/B+ oxygen) was 10 L/minute and for NCtherapy it was 3 L/minute based onconsensus of practice.25 CPAP was star-ted if subjects were hypoxic (SpO2 ,93%) despite oxygen.4 L/minute via FMor .2 L/minute via NC. CPAP was dis-continued once subjectswereweaned to1 to 2 cmH2O pressure and were nolonger hypoxic in fraction of inspiredoxygen (FiO2) , 0.4 for 1 hour. CPAPfailure was dened as hypoxia (SpO2,93%) despite 9 cmH2O pressure and FiO20.6, whereupon subjects exited the trial.

Those subjects with severe bronchiolitisatpresentation,whorequiredimmediatecommencement of CPAP driven by gas Aor B, followed the CPAP protocol (Fig 1).

Sample Size

Sample size calculation (using nQueryAdvisor v4.0) was based on an unpairedt test with 80% power for a 2-sided a of5% to detect a 0.75-day LoT reduction. Abaseline mean LoT for bronchiolitis of2.7 days (SD= 2.3 days)was assumed.26,27

The calculation showed that 298 sub-jects would be needed to achieve areduction in total LoT by 0.75 days.Three-quarters of a day duration wasselected both from the point of viewof feasibility of recruitment and also

representing a clinically importantthreshold (eg, a 0.75-day LoT reductionin a center that treats 100 infants wouldsave 75 bed-days and was considereda positive impact on health economics).

Randomization and Blinding

After written informed consent wasobtained from parents, patients wereenrolled and allocated to Gas A or B bytelephone using computer-stratiedblock-randomization. Parents/legal guard-ians and clinical/study personnel wereblinded to randomization sequence andallocation. Randomization codes re-mained secure until the end of the trial.For blinding, identical cylinders markedGas A or B and identical equipment andconnectionswereused. TheCPAPoxygendial was blanked off and FiO2 was reg-ulated by the LED display. The air inlet tothe CPAP device was modied to deliverGas A or B using identical connectors.

Statistical Methods

The primary endpoint (LoT) was ana-lysed blind, for all subjects, based onintention to treat, in order to determineany difference in LoT between treat-ment groups known as gas A and gas B.Subgroup LoT data was analyzed forFM, NC subjects and for CPAP subjectswho were severe enough to warrantCPAP from the start. The Mann-Whitneytest was used to compare LoT betweentreatment groups (as data wasskewed), with results summarized asmedians with interquartile ranges

TABLE 1 Modied Woods Clinical Asthma Score

SCORE 0 1 2Pulse oximetry SpO2 . 93%: Room Air SpO2 , 94%: Room Air SpO2 , 94%: 40% FiO2Accessory muscle use NONE of:

Recessions Head bobbing Nasal aring Tracheal tug

ANY one of: Recessions Head bobbing Nasal aring Tracheal tug

ALL four of: Recessions Head bobbing Nasal aring Tracheal tug

Cyanosis No Yes In room air Yes In 40% FiO2Cerebral function Normal Depressed or Agitated ComaBreath sounds Normal Unequal Decreased or absentExpiratory wheezing None Yes

Maximum score = 11.

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FIGURE 1BREATHE treatment protocol.


(IQR). Fishers exact test was used tocompare proportions progressing toCPAP in the two groups. All analyseswere two tailed with an alpha level setat 005. STATA 10 and SPSS 17 wereused for analysis. Change in respira-tory distress over time measured byMWCAS was analyzed for all subjectsas well FM and RSV positive (RSV1)subgroups. Mixed Models methodologywas used since it takes into accountcorrelatedmeasures (gas type, gender,birth gestation, age, weight, virus sta-tus, temperature, heart rate, re-spiratory rate, SpO2). Due to the nature

of the data, the square root trans-formation of MWCAS was used as thedependant variable for the modelling.The modelling and estimation of theeffects of interest was carried out bythe PROCMIXED routine in SPSS version17, with a signicance level set at 5%.

RESULTS

Participant Flow, Recruitment,Baseline Characteristics, andNumbers Analyzed

Infants presenting with any respira-tory signs or symptoms were screened

between the period of 2005 to 2008. Atotal of 361 patients with clinically di-agnosed bronchiolitis were consideredfor eligibility. Consent was obtained for319 subjectswhowere randomized andenrolled into the study. The consortowchart (Fig 2) shows that 3 subjectswere excluded (2 withdrawal of con-sent and 1 screening failure); there-fore, 316 subjects were allocated totreatments. An additional 35 subjectswere excluded because of protocol vi-olation, consent withdrawal, screeningfailure, hospital clinicians decision, orpremature disruption of therapy. Thus,

FIGURE 2Consort owchart.

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281 subjects (140 Heliox and 141 Airox)with similar baseline characteristics(Table 2) completed the study, and theirdata was analyzed. The results aresummarized in Table 3. There were nohospital readmissions for subjectswho had completed or exited the trial.

Length of Treatment

Analysis of data from all 281 subjectsshowed no difference in median LoTbetween treatment groups [Heliox 1.90days (interquartile range 1.083.17)compared to Airox 1.87 days (inter-quartile range 1.113.34), P 5 .41].However, LoTwas signicantly reducedin favor of Heliox for FM-tolerant sub-jects [Heliox, 1.46 days (interquartilerange 0.851.95); Airox, 2.01 days

(interquartile range 0.932.86) P = .03].A more notable reduction in LoT wasseen in RSV+ subjects [Heliox, 1.31 days(interquartile range 0.611.91); Airox,2.18 days (interquartile range 1.402.95) P = .004]. There was no differencein LoT for NC subjects [Heliox 2.51 days(interquartile range1.214.32), Airox2.81 days (interquartile range 1.454.78) P = .53].

Averting Need for CPAP

Analysis of data from all 281 subjectsshowed no reduction in proportion ofcases progressing to CPAP [24 of 140Heliox subjects (17%) vs 27 of 141 Airoxsubjects (19%); odds ratio 0.87 (0.471.60), P 5 .76]. However, for FM toler-ant RSV1 subjects there was a 66%

reduction in proportions requiring CPAPin favor of Heliox, at borderline signi-cance [3 of 27 Heliox subjects (11%) vs10 of 31 Airox subjects (32%); odds ratio0.26 (.071.02), P5 .76]

Impact on CPAP Efcacy

Heliox signicantly reducedmedian LoTfor severe bronchiolitic subjects whowere started directly onto CPAP [Heliox1,55 days (interquartile range 1.382.01), Airox 2.26 days (interquartilerange 1.842.73); P = .02].

Impact on Respiratory Distress

Heliox reduced respiratory distress inall 281 subjects across all time pointsand statistically signicant at 8 hoursonwards. MWCAS (mixed models esti-mate = 20.1298; 95% condence in-terval 20.202 to 20.057, P , .001).Regardless of gas type, FM was moreeffective than NC (mixed models esti-mate5 0.093; 95% condence interval0.005 to 0.181, P = .04).

Adverse Events

Six subjects required intubationfor different reasons. In one casethere was CPAP equipment malfunc-tion which precipitated emergency

TABLE 2 Baseline Characteristics of Subjects in the Study

Baseline Characteristics Units Heliox (N = 140) Airox (N = 141)

Gender male:female ratio 1:1.59 1:1.52Gestation at birth wk 39.0 (38.0240.0) 40.0 (38.0240.0)Age at presentation wk 10.90 (5.85225.50) 17.70 (6.80229.40)Weight at presentation kg 5.65 (4.3427.70) 5.70 (4.4027.70)NPA +ve at presentation N (% of cases) 111 (79.3%) 116 (82.3%)Temperature C 37.0 (37.0238.0) 37.0 (37.0238.0)Heart rate beats per min 152.0 (136.02165.0) 148.5 (133.52168.0)Respiratory rate breaths per min 56.0 (44.0262.0) 53.0 (47.0263.5)SpO2 in room air % 92.0% (89.0295.0) 91.0% (89.0294.0)Modied Woods Clinical

Asthma ScoreMaximum score of 11 3.0 (2.023.0) 3.0 (2.024.0)

Values are medians and IQRs. NPA, nasopharyngeal aspirate virus detection.

TABLE 3 Summary of BREATHE Findings

Impact on LoT Intervention N Mean LoT (95% Condence Interval), days Median LoT (Interquartile Range), days P

All subjects Heliox 140 2.268 (1.993 to 2.544) 1.902 (1.08323.173) .41Airox 141 2.487 (2.180 to 2.794) 1.865 (1.11423.344)

NC (6CPAP) Heliox 40 2.952 (2.335 to 3.569) 2.505 (1.21024.315) .53Airox 47 3.296 (2.643 to 3.948) 2.810 (1.45024.780)

FM (6CPAP) Heliox 44 1.538 (1.234 to 1.841) 1.464 (0.85221.947) .03Airox 40 2.236 (1.744 to 2.728) 2.006 (0.92822.859)

FM (6CPAP), RSV+ Heliox 27 1.411 (0.982 to 1.841) 1.310 (0.60821.906) .004Airox 31 2.456 (1.868 to 3.044) 2.179 (1.39622.951)

CPAP LoT Heliox 9 1.619 (1.301 to 1.934) 1.552 (1.38022.013) .02Airox 12 2.380 (1.773 to 2.986) 2.258 (1.84422.727)

Proportion of cases needing CPAP Percent Odds Ratio (95% Condence Interval)All cases Heliox 24/140 17% 0.87 .78

Airox 27/141 19% (0.4721.60)FM, RSV+ Heliox 3/27 11% 0.26 .07

Airox 10/31 32% (0.0721.02)

Impact on MWCAS Comparison Estimate of Fixed Effects (95% Condence Interval)Results are Heliox effect relative

to Airox over timeAll patients 20.1298 (20.202 to 20.057) ,.001FM relative to NC 0.093 (0.005 to 0.181) .04


intubation. Two subjects suffered re-current apnoeas immediately followingenrolment (i.e. screening failure). Onesubject due to receive CPAP was intu-bated and transferred out because nohigh dependency bed available whileone subject was intubated because ofdelay in high dependency bed avail-ability. One subject had a previouslyundetected patent ductus arteriosusand was therefore referred to thecardiologists.

DISCUSSION

Bronchiolitis is a leading cause of infanthospitalization worldwide yet, to date,oxygen and supportive care are themainstay of treatment for the vastmajority of patients. The excellent safetyprole and unique physical properties ofHeliox position it as a potentially usefultherapy for acute bronchiolitis. TheBREATHE study found the deliverymethodof Heliox to be crucial to its efcacy: itwas only benecial if given by a tight-tting FM or by CPAP. Thus, if deliveredeffectively, Heliox therapy signicantlyreduced length of hospital treatment atdifferent points of care (ward, PICU). TheBREATHE study was powered to detecta 0.75-day reduction in LoT. However,the statistically signicant nding ofa 0.55-day reduction in LoT in FM-tolerantpatients is still a clinically useful nd-ing, given the very signicant pressureon hospital beds every winter imposedby bronchiolitis. Furthermore, given theneedto justify thehealth-economiccostofHeliox, the results of the subgroup anal-ysis support the rational use of Heliox inRSV+ patients who showed a greaterreduction in LoT (0.87 day).

Heliox rapidly reduced respiratory dis-tress, making it a potentially usefulstabilization tool in emergency care. Theeffect was greater when consideringRSV+ subjects (archetypical bronchiol-itis), consistent with Martinon-Torresndings on his group of RSV+ subjects.16

However, the authors of that study found

Heliox shortened the length of hospitalstay. Because many other variables canaffect the length of hospital stay, wechose to measure total LoT as the pri-mary end point, because it is directlylinked to therapy.

We found Heliox conferred no benetover oxygen when delivered by NC atow rates of #3 L/minute. We believethe difference in efcacy between FMand NC is caused by several factors. Atight-tting FM is used in clinical sit-uations when the highest FiO2 needs tobe delivered with minimal air entrain-ment. Delivering a high concentrationof helium must also be very importantfor Heliox therapy, and our previousndings28,29 also provide support foruse of the nonrebreathing FM. The useof an NC is subject to signicant airentrainment, and thus variable FiO2, asdemonstrated by Sung et al.30 The dis-advantages of the NC would be magni-ed when using Heliox, a much lightergas. Furthermore, in small infants,nasal prongs may also increase re-sistance to nasal airow and work ofbreathing. It is not surprising thereforethat NC therapy with Heliox at conven-tional ow rates is ineffective.

The BREATHE study is the only RCT thusfar to investigate the rate of CPAP use inbronchiolitis. However, the observed66% reduction only reached borderlinestatistical signicance, which may bebecauseoftherelativelysmallnumberofCPAP subjects (n = 58). Martinon-Torreset al17 in their Heliox-CPAP study dem-onstrated a reduction in work ofbreathing and improved CO2 clearance.The BREATHE study also enabled as-sessment of the impact of Heliox onCPAP efcacy. We analyzed data forsubjects who were started on CPAPfrom the beginning of the trial becausetheir pathophysiology had not yet beenaltered by previous therapy. We foundthat CPAP duration was signicantlyreduced if Heliox was the driving gas forCPAP. The numbers of subjects totaled

only 21, so we cannot draw any strongconclusions. However, if the nding ofreduced treatment time was to be rep-licated in a larger CPAP study, thiswouldrepresent a signicant health-economicbenet for using Heliox to drive CPAP incases of severe bronchiolitis.

We did not select patients based onclinical severity but screened consec-utive infants presenting with any re-spiratory signs or symptoms and found361 patients with clinically diagnosedbronchiolitis. We could not rule out thepossibility that some patientsmay havehad asthma. However, any cases ofasthma-bronchiolitis overlap wouldhave been balanced out between the 2treatment groups through the processof randomization. Virus detection fromnasopharyngeal aspirate was carriedout by the hospitals on 281 of the en-rolled patients. We found 227 of 281(80%) were virus positive, with RSVaccounting for the vast majority. Thecenters routinely assayed only for RSV,para-inuenza, adenovirus, Flu A/B,and rhinovirus. Therefore, the 80% vi-rus positive rate (Table 2) was mostlikely an underestimate and we arecondent that our clinical selectioncriteria captured mostly viral bron-chiolitis.

The BREATHE study is the largest phaseIII, multicenter, double-blinded RCT ofHeliox in bronchiolitis. It attempted toresolve the challenges of blinding. Theuse of special hosingmaterial, identicalin appearance for Heliox and Airox en-sured that there was no difference insound generation that could havealerted the investigator to identify thestudy gas.

The BREATHE study linked efcacy to themode of delivery: CPAP or tight-ttingnonrebreathing FM. However, thelarge number of subjects treated by NCmeant that the positive ndings in favorofHelioxwere limited toonly84subjectswho tolerated the FM. Although the useof the FM was a major limitation of this

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study, we chose it as the delivery in-terface because it is readily available,and others13,16 had reported effectiveHeliox delivery by FM. Our previousresearch28,29 also found that a tight-tting 3-valve, nonrebreathing FMwould deliver the highest concentra-tion of oxygen and helium. However,FMs are generally poorly tolerated inyoung children, and this was also ourexperience. To maximize FM compli-ance in their study, Martinn-Torreset al16 used swaddling to comfort-ably restrain subjects with the FM heldagainst the face by soft elasticizedtube netting applied over the head. Weused a bonnet to allow a tighter-ttingFM and help prevent the elastic bandfrom slipping down, used swaddling,and encouraged staff and mothers tomaximize compliance. Despite ourbest efforts, many subjects did nottolerate the FM, and it proved impos-sible to apply it continuously. Maskintolerance was highlighted after re-cruitment of the rst few subjects intothe trial when we found nursing staffwishing to use an NC, the commonlyused mode of oxygen delivery forinfants. It was considered unethical towithhold a trial gas treatment if sub-jects had already started to improve.We therefore considered delivery oftrial gas via NC because Williamset al31 successfully used NC with Helioxin infants, and oxygen is already con-ventionally administered via NC. There-fore, NC was included as a protocolamendment for subjects who were FMintolerant.

We prospectively studied a cohort ofclinically diagnosed bronchiolitic in-fants, regardless of severity and viraletiology, enabling us to identify a treat-ment for bronchiolitis that can be usedacross different modalities (FM andCPAP) and points of care (emergencydepartment, ward, and PICU). Nonethe-less, this approach to recruitmentresulted in a smaller proportion of

severe cases, making it difcult to con-clusively study outcomes such as CPAP.The latter is very important becauseCPAP compared with standard treat-ment has been shown to improve ventila-tion, with a reduction in hypercapnea,32

with growing consensus that CPAP ther-apy prevents deterioration and need formechanical ventilation.

We did not collate data on length of staybut rather focused on length of treat-ment. The study was powered for thelatter because LoT was a clear anddenitive endpoint in the disease pro-cess.

The BREATHE study was not powered toinvestigate intubation rates, whichwould also have been informative. Only8 of 316 (2.8%) needed intubation.Therefore, amuch larger sample size ora moderate number of a more selectedsevere group of patients would beneeded to investigate the impact ofHeliox on intubation rates. The BREATHEprotocol (part B, not yet carried out)had originally been designed to in-vestigate intubation rate in a moresevere subgroup of bronchiolitics (de-ned as already requiring CPAP). Abaselinegure of 35%was assumed forthe bronchiolitis intubation rate (de-ned as CPAP failure) derived fromdatafor our PICU at St Marys hospital. Thepower calculation showed that a totalof 86 severe bronchiolitics on CPAPwould need to be recruited to detecta reduction in the intubation rate from35% to 10% with 80% power.

The BREATHE study has highlighted theneed to review our approach to re-spiratory care in general: use of FM hastolerance issues, and NC (at conven-tional ow rates) has limited efcacy.Although NC delivery of Heliox at owrates ,3 L/minute was ineffective, wetheorize that at higher ow rates (tol-erated based on our anecdotal experi-ence), Heliox therapy by nasal cannulamay be effective. A well-designed RCTcomparing 3-valve nonrebreathing FM

versus high-ow NC therapy is neededto identify the optimal method of de-livery. Furthermore, a sufciently pow-ered RCT of Heliox-driven versusconventional Airox-driven CPAP woulddetermine whether Heliox reduces theneed for mechanical ventilation.

In the meantime, the clinical practicerecommendations arising from theBREATHE study ndings are as follows:

Heliox therapy should be startedfor bronchiolitic infants who re-quire hospital admission for treat-ment of hypoxemia or respiratorydistress.

If the use of Heliox therapy needsto be rationalized, it could be tar-geted to those who are RSV posi-tive.

Heliox therapy should only be de-livered via a tight-tting nonre-breathing FM or CPAP, as per theprotocol outlined in the BREATHEstudy.

CONCLUSIONS

The BREATHE study showed that thedeliverymethodofHeliox is critical to itsefcacy. Heliox is effective if deliveredvia a tight-tting nonrebreathing FM orCPAP but not via a NC at conventionalowrates.With effective delivery, Helioxreduces the LoT, alleviates respiratorydistress, improves CPAP efcacy, andmay reduce the need for CPAP. A moreacceptable patient interface for effec-tive delivery remains the challenge forindustry if Heliox is to be more widelyused in pediatric respiratory care.

ACKNOWLEDGMENTSWe thank the patients, families, andnursing, medical, and other healthcarestaff across all the hospitals, whosecooperation and support allowed usto undertake the BREATHE trial. We es-pecially thank the BREATHE team mem-berswhosemeticulousattention to trialconduct ensured the rigor of this study.


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(Continued from rst page)

PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).

Copyright 2013 by the American Academy of Pediatrics

FINANCIAL DISCLOSURE: Dr Bland was a Clinical Director of British Oxygen Company (BOC) Medical during the period of conduct of this trial; the other authorshave indicated they have no nancial relationships relevant to this article to disclose.

FUNDING: Supported by a research grant from BOC Medical and equipment support from Fisher and Paykel Healthcare, EME (Electro-Medical Equipment)Carefusion, and Covidien Nellcor.

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DOI: 10.1542/peds.2012-1317; originally published online March 18, 2013; 2013;131;661Pediatrics

Hubert Bland and Parviz HabibiCaroline Pao, Arvind R. Shah, Elizabeth Reus, Joseph Eliahoo, Fabiana Gordon,

Mina M. Chowdhury, Sheila A. McKenzie, Christopher C. Pearson, Siobhan Carr,Randomized Controlled Trial

Heliox Therapy in Bronchiolitis: Phase III Multicenter Double-Blind

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Hubert Bland and Parviz HabibiCaroline Pao, Arvind R. Shah, Elizabeth Reus, Joseph Eliahoo, Fabiana Gordon,

Mina M. Chowdhury, Sheila A. McKenzie, Christopher C. Pearson, Siobhan Carr,Randomized Controlled Trial

Heliox Therapy in Bronchiolitis: Phase III Multicenter Double-Blind

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