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eureca

Indian Pediatr 2010;47: 1047-1050

Steam Inhalation in Respiratory Illnesses - Full Steam Ahead or Full Stop? A Systematic Review of Randomized Controlled Trials


Joseph L Mathew

Advanced Pediatrics Centre, PGIMER, Chandigarh 160 012, India.
Email: [email protected]
 


The clinical question in this EURECA is: "Does steam inhalation (Intervention) result in clinical improvement (Outcome) in people with respiratory illness (Population), as compared to no steam inhalation/placebo (Comparison)? The clinical conditions include upper (common cold, croup, sore throat) and lower (bronchiolitis, pneumonia) respiratory tract illnesses.

Relevance

Steam inhalation is perhaps one of the most widely prevalent home-based practices, amongst laity and the professionals; based on the perception that warm humidified air provides subjective relief of respiratory symptoms, by loosening the respiratory secretions(1). Advances in understanding of pathophysiology of respiratory infections/illnesses and development of specific therapy; make it important to examine this age-old ‘remedy’ in the light of modern evidence-based health-care practice.

Current Best Evidence

A Medline (through Pubmed) search updated on 25th October 2010, using the term "steam" and Limits: Clinical trials, randomized controlled trials and meta-analysis; short-listed 8 potentially relevant publications(1-8) including five relevant RCTs(2-6). Simultaneous Cochrane Library search with the term "steam" and filter "Record Title, Abstract or Keywords" yielded 4 Cochrane Reviews(9-12), 1 Cochrane review protocol(13), and 103 Clinical Trials. One Cochrane review(9) and the protocol(13) were relevant; two did not deal with steam/heated humidified air inhalation(10,12), and one evaluated steam in ventilated patients(11). No additional trials were identified. Scanning reference lists of included publications yielded one more trial(14). Thus a total of six trials were relevant to this review; five evaluated steam in adults with common cold(2,3,5,6,14); only one trial was conducted in children (with pneumonia or bronchiolitis)(4). This trial lacked the methodological refinements of the other trials. Characteristics of included studies are summarized in Table I.

Table I



Summary of RCTs Examining Steam Inhalation in Respiratory Illnesses
No Study design n (steam/control) Intervention Results Outcomes Ref
1 DB, PC, RCT 62 (32/30) Nasal inhalation of air at 42-44 C twice x 20 min versus air at 22-24 C Subjective response daily × 7 dPeak nasal inspiratory and expiratory flow (patency) on d1,d2,d7 Subjective improvement : 26/32 vs 7/30 Increased nasal patency 61-74% vs 6-8%. 2
2 DB, PC, RCT 66 (32/34) Nasal inhalation of air at 40-42 C twice versus air at 20-24 C Subjective symptom scores for nasal congestion, nasal drainage, and sneezing. Nasal resistance using rninomanographer. Subjective improvement on d7 : 24/32 vs 34/34Nasal resistance improvement 6% vs 11%.Side effects 36% vs 9% 3
3 DB, PC, RCT 68 (32/36) Inhalation of air at 47 C × 60 min to raise nasal temp to 43 C versus air at 20-24 C Subjective symptom scores for nasal congestion, nasal drainage, and sneezing. objective measures of nasal resistance No significant difference in daily symptom scores. Improvement in nasal resistance favoring placebo on d7 5
4 RCT 20 Nasal inhalation of air at 42-44C at 24 and 48 hr after infection versus air at 22-24 C. Improvement in symptom scores. Nasal washing viral titres (shedding) over 4 days Mean viral titres (/mL)
10(1.7) vs 10(1.8)
10(1.7) vs 10(1.9)
10(1.2) vs 10(1.6)
10(0.9) vs 10(0.7)
6
5 RCT, DB 96 (87 records available) 45/42 Nasal inhalation of air at 43C versus air at air at 30C. Subjective improvement Proportion No difference in proportion 14
6A RCT 16 Steam inhalation within a cloth tent versus no steam Respiratory status at 0, 6h, 48h In bronchiolitis, less time for recovery and less duration of hospitalization 4
6B same as above 20 same as above same as above No difference in improvement. 4
DB=double blind, PC=placebo controlled, RCT=randomized controlled trial.

The Cochrane review on common cold(9) was updated till May 2006; no additional trials are identified. Hence the data therein can be considered current, but a few methodological errors necessitate a fresh review.

Data from the common cold trials were heterogeneous (in terms of participants, outcome measures, timing of measurement, and baseline status. One trial(2) suggested subjective improvement with steam; another(3) suggested the opposite and yet another showed no difference(5). Meta-analysis did not show benefit (RR for non-improvement=1.78; 95%CI 0.01-226.51). The single trial in children with pneumonia showed no benefit of steam, but some benefit in bronchiolitis(4). No data were found pertaining to croup and sore throat. There was limited data on the adverse events associated with steam inhalation especially the risk of burns/scalds in infants and children.

Critical Appraisal

At first glance, this EURECA systematic review does not appear to present significant new findings in terms of management, except that there are no scientific grounds to encourage steam inhalation in children. However, it presents the opportunity to critically appraise a few important issues.

Is steam inhalation relevant in modern practice? It must be noted that the practice of steam inhalation could have been relatively justifiable at a time when there was limited understanding of pathophysiologic mechanisms in various respiratory tract illnesses; coupled with limited therapeutic options. Presently, both situations have dramatically changed for most respiratory conditions.

Subjective versus objective improvement: It is interesting that subjective improvement/perception of relief; often does not correlate with objective measurements. This raises the tricky issue of whether, ‘feeling better’ is superior to ‘being better’. In the context of conditions as diverse as acute common cold to chronic arthritis, the former cannot be ignored, and may take precedence over precise objective measurements. On the other hand, for most other clinical conditions, demonstration of subjective improvement may be inadequate to prove that an intervention works. The precise balance between subjective and objective outcome measures in common cold, is not clear. Moreover, the subjective and objective outcome measures reported in adult studies are difficult to replicate in children, necessitating less robust methods to evaluate benefit. This could alter the results of pediatric trials significantly.

Is there any harm in recommending steam inhalation? Many care-givers (physicians and parents) may prefer to opt in favour of steam inhalation, based on personal (favourable) experiences, and might argue that this outweighs the (absence of) data from research studies. It must be emphasized that one of the goals of evidence-based health-care is to protect patients from precisely this tendency.

Extendibility

Most of the included trials recruited adults, delivered hot humidified air, through commercial devices and used complex objective measurements. The lone pediatric trial was limited in terms of quality and quantity, to draw a meaningful conclusion in favor of steam inhalation. Hence strictly speaking, the data is not extendible to the population of interest.

Funding: None.

Competing interest: None stated.


EURECA Conclusions in the Indian Context

There is not enough evidence supporting benefit of steam inhalation in acute (upper and lower) respiratory illnesses in children.
 

References

1. Sanu A, Eccles R. The effects of a hot drink on nasal airflow and symptoms of common cold and flu. Rhinology 2008; 46: 271-275.

2. Ophir D, Elad Y. Effects of steam inhalation on nasal patency and nasal symptoms in patients with the common cold. Am J Otolaryngol 1987; 8: 149-153.

3. Macknin ML, Mathew S, Medendorp SV. Effect of inhaling heated vapor on symptoms of the common cold. JAMA 1990; 264: 989-991.

4. Singh M, Singhi S, Walia BN. Evaluation of steam therapy in acute lower respiratory tract infections: a pilot study. Indian Pediatr 1990; 27: 945-951.

5. Forstall GJ, Macknin ML, Yen-Lieberman BR, Medendrop SV. Effect of inhaling heated vapor on symptoms of the common cold. JAMA 1994; 271: 1109-1111.

6. Hendley JO, Abbott RD, Beasley PP, Gwaltney JM Jr. Effect of inhalation of hot humidified air on experimental rhinovirus infection. JAMA 1994; 271: 1112-1123.

7. Ghimire A, Das BP, Mishra SC. Comparative efficacy of steroid nasal spray versus antihistamine nasal spray in allergic rhinitis. Nepal Med Coll J 2007; 9: 17-21.

8. Moore M, Little P. Humidified air inhalation for treating croup: a systematic review and meta-analysis. Fam Pract 2007; 24: 295-301.

9. Singh M. Heated, humidified air for the common cold. Cochrane Database Syst Rev 2006; 3: CD001728.

10. Moore M, Little P. Humidified air inhalation for treating croup. Cochrane Database Syst Rev 2006; 3: CD002870.

11. Kelly M, Gillies D, Todd DA, Lockwood C. Heated humidification versus heat and moisture exchangers for ventilated adults and children. Cochrane Database Syst Rev 2010; 4: CD004711

12. French SD, Cameron M, Walker BJ, Reggars JW, Esterman AJ. Superficial heat or cold for low back pain. Cochrane Database Syst Rev 2006; 1: CD004750.

13. Umoren R, Odey F, Meremikwu MM. Steam inhalation or humidified oxygen for acute bronchiolitis in children up to three years of age. Cochrane Database Syst Rev 2007; 2: CD006435.

14. Tyrrell D, Barrow I, Author J. Local hyperthermia benefits natural and experimental common colds. BMJ 1989; 298: 1280-1283.
 

 

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