Am J Otolarynsol 3:149-153, 1987

Effects of Steam Inhalation on Nasal Patency and Nasal

Symptoms in Patients with the Common Cold

D o v OPHIR, MD, AND YICAL ELAD, PHD

The effects of steam inhalation on nasal patency and on nasal symptoms were studied in 62 patients with the common cold by a double-blind, randomized, placebo-controlled clinical trial. Treatment consisted of two 20-minute sessions, during which the patient inhaled saturated, hot (42 ~ to 44~ air through the nose. The subjective response was recorded by each patient during the week following treatment on a daily symptom score card. Nasal patency was determined before treatment, the following day, and 1 week later by measuring peak nasal expiratory and inspiratory air flow. Highly reproducible results were obtained by using these objective methods. Steam inhalation resulted in alleviation of cold symptoms and increased nasal patency in a significantly higher percentage of patients in the actively treated group than in the placebo- treated group. Possible explanations for the effectiveness of treatment are discussed.

Inhalation of humidified warm air has long been regarded as an effective means of alleviating cold symptoms. Elevation of intranasal temperature is reportedly effective in reducing nasal resis- tance, 1 whereas exposure to cold air causes in- creased nasal resistance. 1-4 High temperature also is known to be detrimental to the infectivity of rhinoviruses, ~ the most important group of cold viruses. Based on this knowledge, we decided to conduct a double-blind, controlled clinical study to assess subjective patient response and to mon- itor the changes in nasal patency that occur in patients with the common cold treated by in- halation of humidified warm air through the nose,

SUBJECT AND METHODS

Subjects

This study was approved by the Kaplan Hos- pital Human Investigation Committee. It was conducted during the winter months to ensure a

sufficient number of patients with the common cold. Seventy such patients volunteered in re- sponse to local advertising and were randomized into two groups consisting of 35 individuals each. Drop-out rates were 8.6% (three patients) from the actively treated group and 14.2% (five pa- tients) from the placebo-treated group. The re- suiting study population consisted of 62 volun- teers, 27 men and 35 women. Their ages ranged from 16 to 64 years (mean, 34 years). Patients whose history and anterior rhinoscopy con- firmed the diagnosis of common cold were in- formed about the procedure, and written consent was obtained. Symptoms had to be judged as suf- ficiently severe to merit patient admission to the trial. Excluded from the study were patients with a history of allergic rhinitis or whose symptoms lasted more than three days; patients with exu- dative pharyngitis, tonsillitis, or temperature higher than 38~ and patients with deviated na- sal septums obstructing the nasal airways.

Methods

Received October 27, 1986, from the Department of Oto- laryngology, Kaplan Hospital (Dr. Ophir), and the Hebrew University of Jerusalem, Israel [Dr. Elad), Accepted for pub- lication December 1, 1986.

Address reprint requests to Dr. Ophir: Department of Oto- laryngology, Kaplan Hospital 76100 Rehovot, israel.

0196-0709/87 $0,00 + .25

Two instruments were used in the clinical trial. One was a specially designed device (Rhinoth- erm, Netzer Sereni, Israel--patent pending) from which a constant flow (40 L/min} of water-satu- rated hot air (42 o to 44~ was directed into the

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EFFECTS OF STEAM INHALATION IN COMMON COLD PATIENTS

nasal passages through two exhaust nozzles. The patient was instructed to breathe by inhaling through the nose and exhaling through the mouth. The other was a placebo (dummy) instrument identical in appearance to the genuine one, but which delivered air at room temperature (20 ~ to 24~ and at a flow rate of only 5% as compared to the active device. The flow rate was reduced to avoid possible damage to the nasal mucosa by a high-rate flow of air at 20 ~ to 24~ The placebo device produced a noise identical to that of the genuine device.

Patients selected for the study were treated with either the active or the placebo device on a dou- ble-blind, randomized basis. They were told that treatment was to he at different temperatures but no preference was expressed by the experimen- ters for a particular temperature. A full course of therapy consisted of two treatments, each lasting 20 minutes, with a 60- to 90-minute interval. The duration of the treatment sessions and the time intervals were selected arbitrarily.

Because the symptoms of common cold im- prove rapidly regardless of therapy, follow-up evaluation of one week's duration was consid- ered appropriate. Patients were examined before treatment, the next morning, and 1 week later. They were asked to avoid any drug therapy dur- ing the week of follow-up evaluation.

than SI itself, was used as the basis for evaluation of results to avoid distortions arising from dif- ferences in baseline (pretreatment) measure- ments.

Changes in nasal potency were evaluated by measuring alterations in nasal air flow using two methods: 1) measurement of peak inspiratory flow (PIF), using the Youlten Peak Nasal Inspiratory Flow Meter (Clement Clarke Ltd., London, Eng- land); and 2) measurement of peak expiratory flow (PEF), using the Mini-Wright Peak Flow Me- ter (Clement Clarke Ltd.). After blowing the nose, the patient was fitted with an airtight face mask applied over the nose and attached to the flow meter, and measurements were recorded. Care was taken not to disturb the nasal anatomy and to avoid air leakage. The values, expressed in L min -1, were determined as the mean of three re- cordings taken after the patient had become fa- miliar with the technique and repeated record- ings showed a reproducible pattern. The physician who performed the measurements was not told whether the genuine or the placebo device was being used. Peak expiratory air flow through the mouth was determined using the Mini-Wright Peak Flow Meter without a mask. A blockage index (BI), taking into account the effect of lower airway resistance on PEF, was calculated ac- cording to the formula of Taylor et al.6:

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Evaluation of Results

Subjective response was assessed by an indi- vidual daily score card on which the severity of three symptoms (sneezing, nasal blockage, and nasal discharge) was recorded by the patient ac- cording to a four-point scale where 0 = no symp- toms, 1 = mild symptoms, 2 = moderate symp- toms, and 3 = severe symptoms. Adverse side effects, if present, also were recorded.

Numbers on the score card were recorded by the patient before undergoing the treatment and once a day during the week following treatment. A symptom index (SI) was calculated for each day by dividing the sum of the numbers recorded on that day by 3 (the total number of symptoms). Following treatment, the percentage change in SI relative to the pretreatment SI was calculated daily, according to the formula

A (1 - = ) • loo

.IO

where A = SI on that day and B = SI before treatment. The percentage change in SI, rather

B I = PEF (mouth) - PEF (nose)

PEF (mouth)

For each method, results were recorded in terms of the percentage change in nasal potency fol- lowing treatment. The mean values obtained for actively treated and placebo-treated patients are presented in Table 1. The data in Table 1 also include cases in which treatment failed to yield improvement.

TABLE 1. Changes in Peak Inspiratory Flow, Peak Expiratory Flow, and Blockage Index Following

Treatment*

PEAK PEAK INSPIRATORY EXPIRATORY

TIME FLOW FLOW BLOCKAGE INDEX AFTER

TREATMENT Active Placebo Active Placebo Active Placebo

One day 42.85 -6 .15 59.25 2.65 36,21 5.6t One week 62.6 58.4 64.3 61.0 42.1 39.6

*All values are given in percentages. Negative values in- dicate a decrease in nasal potency, Significance was deter- mined by comparing the results after placebo and active treat- ments for each measurement method.

tP < .01. 5P < .001.

OPHIR AND ELAD

Statistical Analysis

Experimental data obtained from both objec- tive methods of measurement (PIF and PEF) were subjected to regression analysis to examine their reliability. Analysis of variance, with mean sep- arations accomplished by tests of least significant difference, was carried out at P levels as indi- cated in Table 1.

R E S U L T S

The mean SI values prior to treatment were comparable in the two groups (2.6 and 2.3, re- spectively). The calculated symptomatic im- provement (expressed in percentages) during the week of follow-up evaluation is depicted in Fig- ure 1. Although some improvement occurred in the placebo-treated patients, the percentage change in SI in the actively treated patients was signif- icantly higher. This difference was clearly evi- dent in the first 2 or 3 days after treatment, whereas toward the end of the week of follow-up, the changes observed in the two groups tended to equalize. Symptomatic improvement on the

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TIME AFTER TREATMENT(days)

Changes in daily symptom index (SI) relative to the pretreatment SI during the week following treatment with the active device ($) or with the placebo (o}. The changes are expressed in percentages according to the formula

A 1 - ~ x loo, B

where A = SI on that day and B = SI before treatment. As- terisks denote the significance of difference between corre- sponding pairs of results on each day: *P <.05; **P <.01; ***P <.001.

morning after treatment was reported by 26 of the 32 actively treated patients (81.2%) and by only seven of the 30 patients (23%) treated with the placebo instrument. Symptomatic improve- meat at the end of the follow-up period was re- ported by 92.2% of the actively treated group and 84.6% of the placebo-treated group.

Nasal potency as expressed by PIF, PEF, and BI was increased significantly as a result of the active treatment compared with the results of the placebo treatment, where it showed almost no change or even deterioration after treatment (Ta- ble 1). No significant difference in nasal patency between the groups was observed at the end of the week. The percentage of patients in whom nasal potency in terms of PIF and PEF improved on the morning after treatment was 61,0 to 74.1% in the actively treated group and 6.3 to 8.0% in the placebo-treated group.

No statistically significant age- or sex-related differences were observed in the subjective re- sponses to treatment The parameters measured by the objective methods showed a highly sig- nificant degree of intercorrelation (P < .01).

All patients found the method of saturated hot air delivery to be acceptable, One patient suffered from temporary dizziness for 2 to 3 minutes fal- lowing treatment. No other side effects were noted,

D I S C U S S I O N

Common colds are the most frequently occur- ring acute illnesses suffered by man and account for more time lost from work and school than any other cause. 7 They also are responsible for a great deal of discomfort arising from congested and hypersecreting nasal mucosa as well as the general malaise that characterizes the disease. The etiology of the majority of these illnesses has been established. Influenza viruses, parainfluenza vi- ruses, respiratory syncytial viruses, coronavi- ruses, adenoviruses, herpes viruses, and picor- naviruses all account for a proportion of common colds .8 Of these viruses the most important is the rhinovirus group, which causes 30 to 40% of all colds. 9 Because of the large number of distinct serotypes, it is unlikely that effective rhinovirus vaccines will be developed in the near future. Interferon, an antiviral drug, was found to reduce the incidence and severity of cold symptoms in volunteers, but its effectiveness has been con- fined so far to prophylaxis. 10'11 Steam inhalation is a popular method for treating cold symptoms, but the widespread belief in its efficacy has never been put to the test in a controlled clinical trial.

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EFFECTS OF STEAM INHALATION IN COMMON COLD PATIENTS

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The present double-blind, placebo-controlled study shows that this treatment is indeed effec- tive in reducing the duration and severity of com- mon cold symptoms.

Clinical trials aimed at assessing the effects of various stimuli or drugs on nasal symptoms in common cold patients usually have been based on subjective patient response. 12-14 While the symptom score represents an important clinical parameter for the evaluation of patient reaction, objective and quantitative methods are needed as well. Measurements of mucus production ~5 counting of the number of handkerchiefs used or comparison of dry and wet weights of handker- chiefs have been used in previous studies, but their validity is questionable because they de- pend on patient compliance and because inter- pretation of the data is not always clear. Nasal obstruction is the symptom used most commonly for objective assessment. Nasal patency can be investigated by means of rhinomanometry. ~8 In the present study, however, we employed the more convenient and simple measurements of peak nasal inspiratory and expiratory air flow, both of which have proved to be of clinical and scientific value in the evaluation of changes in nasal patency.l'!7-21 These methods of measure- ment are clinically applicable for the following reasons: they are simple to use; they do not in- terfere with the anatomy of the nose, thus allow- ing physiologic air flow to be maintained; they are comfortable for the patient; and, most im- portantly, once the patient has learned the tech- nique following a brief period of instruction and exercise, the results are reliable and reproduc- ible.

Figure 1 indicates the severity of symptoms according to the patients' entries on the symptom score cards following treatment. The mean change in SI on the day after treatment was 70% in the actively treated patients and 20% in the placebo- treated group. Eighty-one percent of the actively treated group and 23% of the placebo-treated pa- tients reported symptomatic improvement on the day after treatment. The improvement in the pla- cebo-treated group may be attributed in part to spontaneous recovery from the disease (which is self-limited in any case) and in part to the pla- cebo effect of the treatment. 22 However, results of the objective measurements of nasal patency, performed on the morning after treatment and presented in Table 1, clearly demonstrate the dif- ference between the therapeutic activity of the active device and that of the placebo. Some of the placebo-treated patients even showed a de- creased nasal patency after treatment, as reflected

in the negative values recorded in Table 1. Be- cause most patients recover from the disease within several days, by the end of the week there was no difference in nasal patency between the groups.

Several possible mechanisms may account for the relief from common cold symptoms experi- enced by our patients. Hyperthermia is a reaction of humans and many animal species to infec- tion. 23'24 Its mechanism of action probably is through enhancing general and local host de- fense mechanisms. 25'26 It has been shown, for ex- ample, that elevated temperature potentiates the antiviral activity 27 of interferon as well as its im- munoregulatory effect on suppressor cells. 28 An- other possible mechanism of action of hyper- thermia is through the effect of elevated intranasal temperature on mucosal mast cells. The process of degranulation of mast cells with accompany- ing secretion of pharmacoactive mediators that cause the normal allergic responses of sneezing, nasal stuffiness, and rhinorrhea also may be in- duced by a viral infection of the upper respira- tory tract, causing the same symptoms. 29 It has been shown that cold dry air causes the appear- ance of inflammatory mediators in nasal secre- tion. 30 It is possible that hyperthermia has an inhibitory effect on the release of mast ceil me- diators; two studies have shown the beneficial effect of hyperthermia in the treatment of allergic rhinitis symptoms. 31'32 A third possible mecha- nism stems from the fact that the infectivity of rhinoviruses, the most important group of com- mon cold viruses, is rapidly lost at febrile tem- perature, ~,33 allowing earlier recovery from the viral infection.

The normal intranasal temperature varies be- tween 31~ at the nares and 36~ at the choanae. 34 This temperature gradient contributes to the con- ditioning of the inspired air and the recovery of heat and water from the expired air. Our record- ings, reported elsewhere, 32 show that in the pla- cebo-treated patients intranasal temperature was kept within normal limits. By supplying air un- der controlled conditions of flow, temperature, and saturation in the actively treated patients, it was possible to overcome the conditioning abil- ity of the nasal passages and to increase the in- tranasal temperature during the period of treat- ment.

An additional benefit may come from the effect of humidification of the inspired air on the nasal passages. Spector et al. 19 demonstrated that the use of wetting agents such as saline and propyl- ene and polyethylene glycol leads to subjective and objective improvement in patients with pe-

OPHIR AND ELAD

rennial rhinitis and is useful in decreasing nasal stuffiness.

The favorable effect of steam inhalation on the course of the common cold, resulting in reduced duration and severity of nasal symptoms, justi- fies its clinical application to provide patients with symptomatic relief.

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