Middle-ear pain and trauma during air travel

Abstract

Introduction

Changes in air pressure during flying can cause ear-drum pain and perforation, vertigo, and hearing loss. It has been estimated that 10% of adults and 22% of children might have changes to the ear drum after a flight, although perforation is rare. Symptoms usually resolve spontaneously.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to prevent middle-ear pain during air travel? We searched: Medline, Embase, The Cochrane Library and other important databases up to July 2014 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

Results

We found three studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

Conclusions

In this systematic review we present information relating to the effectiveness and safety of the following interventions: nasal balloon inflation, nasal decongestants (topical), and oral pseudoephedrine.

Key Points

Changes in air pressure during flying can cause ear-drum pain and perforation, vertigo, and hearing loss.

• It has been estimated that 10% of adults and 22% of children might have changes to the ear drum after a flight, although perforation is rare.

• Symptoms usually resolve spontaneously.

We did not find any RCT evidence assessing nasal balloon inflation, but non-RCT evidence suggests that it may prevent symptoms of barotitis in people during air travel compared with controls.

Oral pseudoephedrine compared with placebo may prevent symptoms in adults with previous ear pain during flights.

• We don't know whether oral pseudoephedrine is also beneficial in children, but it may cause drowsiness.

We don't know whether topical nasal decongestants can prevent symptoms of barotrauma compared with placebo.

About this condition

Definition

The normal middle ear and mastoid is filled with air at atmospheric pressure, and the tympanic membrane (eardrum) is most efficient at absorbing sound when the air pressures are the same both sides (i.e., the membrane is not stretched). The air in the middle ear comes from the nasopharynx by way of the Eustachian tube. This is about 36 mm long, with the outer (ear) third having a rigid bony wall tapering to a diameter of less than 1 mm, where it meets the inner (nasopharyngeal) two-thirds, with walls made of cartilage, soft tissue, and muscles. The tube is lined with respiratory epithelium containing goblet cells and mucus glands, and has a carpet of ciliated cells along its floor. The Eustachian tube is usually closed, but may open on swallowing and usually on yawning to allow air to move from the nasopharynx to the middle ear and mastoid to replace the oxygen that has been absorbed by the respiratory mucosa. During ascent in an aeroplane flight, the external pressure drops and it is relatively easy for air to escape from the middle ear down its pressure gradient into the nasopharynx. As the plane starts to descend, the external pressure increases and the Eustachian tube has to open to allow the relatively low middle ear pressures to equalise. This is not so easy, as the increasing external pressures tend to hamper the opening of the Eustachian tube. The increasing external pressure causes the eardrum to be stretched inwards, but the strength and elastic properties of the normal eardrum may be enough to physically withstand this pressure difference — although pain develops. On landing, the pain gradually resolves but observation of the ear usually shows dilated blood vessels running down the handle of the malleus and sometimes slight bruising of the front parts of the membrane. These are common, transient changes that resolve completely and do not cause damage. This is barotitis. Occasionally, there comes a point called the 'critical closing pressure', when the tube cannot open and the pressure differential in the middle ear increases to the extent that changes occur. One such point may occur if there is an outpouring of fluid into the middle ear from the mucosa lining it. The fluid is an exudate or blood or both. Thus, the middle ear fills to a greater or lesser extent with fluid and the pressure on the membrane is relieved (Boyle's Law: P₁V₁ = P₂V₂). The downside of this is that the individual’s hearing becomes significantly reduced, and this may persist for 1 month or more. The alternative is that, in a membrane with a healed perforation, the thin scar gives way and a new perforation develops, thereby instantly overcoming the pressure differential but again leaving some hearing loss and possibly an additional blood-stained discharge. These two complications are called barotrauma and are uncommon given the many plane flights each year. Both of these problems can result in a balance problem with unsteadiness. However, vertigo, with a prolonged sense of unreal movement (which is usually rotary), is very rare and suggests some disruption of the inner ear with a possible perilymph leak.

Incidence/ Prevalence

The prevalence of symptoms depends on the altitude, type of aircraft, and characteristics of the passengers. One point prevalence study found that, in commercial passengers, 20% of adult and 40% of child passengers had negative pressure in the middle ear after flight, and that 10% of adults and 22% of children had otoscopic evidence of changes to the ear drum. We found no data on the incidence of perforation, which seems to be extremely rare in commercial passengers.

Aetiology/ Risk factors

The factors predisposing to barotrauma include the quality of cabin pressurisation and the speed of descent (short haul flights are worse in general), the individual’s anatomy and Eustachian tube function, the state of the respiratory mucosa at the time of the flight (with inflammation from colds, allergies, or sensitivities), and being awake or asleep (asleep is worse because the individual swallows much less). Because of this huge variability, good studies are very hard to perform.

Prognosis

Experience in military aviation shows that most perforations will heal spontaneously in adults.

Aims of intervention

To prevent middle-ear pain and trauma during air travel, with minimal adverse effects.

Outcomes

Barotrauma (includes incidence and severity of pain and hearing loss, and incidence of perforation of ear drum); adverse effects.

Methods

Clinical Evidence search and appraisal July 2014. The following databases were used to identify studies for this systematic review: Medline 1966 to July 2014, Embase 1980 to July 2014, and The Cochrane Database of Systematic Reviews 2014, issue 6 (1966 to date of issue). Additional searches were carried out in the Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment (HTA) database. We also searched for retractions of studies included in the review. Titles and abstracts identified by the initial search, run by an information specialist, were first assessed against predefined criteria by an evidence scanner. Full texts for potentially relevant studies were then assessed against predefined criteria by an evidence analyst. Studies selected for inclusion were discussed with an expert contributor. All data relevant to the review were then extracted by an evidence analyst. Study design criteria for inclusion in this review were published RCTs and systematic reviews of RCTs in the English language, at least single-blinded, and containing more than 20 individuals (10 in each arm), of whom more than 80% were followed up. There was no minimum length of follow-up. We excluded all studies described as 'open', 'open label', or not blinded unless blinding was impossible. We included RCTs and systematic reviews of RCTs where harms of an included intervention were assessed, applying the same study design criteria for inclusion as we did for benefits. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. To aid readability of the numerical data in our reviews, we round many percentages to the nearest whole number. Readers should be aware of this when relating percentages to summary statistics such as relative risks (RRs) and odds ratios (ORs). We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table.

GRADE Evaluation of interventions for Middle-ear pain and trauma during air travel.

Important outcomes	Barotrauma
Studies (Participants)	Outcome	Comparison	Type of evidence	Quality	Consistency	Directness	Effect size	GRADE	Comment
What are the effects of interventions to prevent middle-ear pain during air travel?
1 (83)	Barotrauma	Topical nasal decongestants versus placebo	4	–1	0	0	0	Moderate	Quality point deducted for sparse data
2 (272)	Barotrauma	Oral pseudoephedrine versus placebo in adults	4	–1	0	0	0	Moderate	Quality point deducted for uncertainty about assessment of outcome
1 (91)	Barotrauma	Oral pseudoephedrine versus placebo in children	4	–2	0	0	0	Low	Quality points deducted for sparse data and for analysis of a different measure than that randomised (children randomised, but analysis based on number of flights)

We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.

Glossary

Barotitis

Symptoms and signs that arise from air pressure changes across the eardrum. There can be a feeling of blockage and fullness and even pain, with a reduction in the hearing and possibly tinnitus. The eardrum often has dilated blood vessels appearing on the malleus handle and the adjacent ear canal skin, and there may even be some bruising of the anterior parts of the membrane, but the middle ear remains air filled and the eardrum intact. These effects are transient and usually resolve spontaneously.

Barotrauma

Symptoms resulting from severe air pressure changes across the eardrum causing physical changes to the eardrum and/or middle ear. There is increasing discomfort and pain (as per the original definition of 'trauma', from the Greek meaning 'a wound'), with reduced hearing and possibly tinnitus. There may be unsteadiness and in very rare cases even vertigo. The middle ear can fill with exudate or blood, and a weakened eardrum can perforate, resulting in a blood-stained discharge.

Low-quality evidence

Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

Moderate-quality evidence

Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.

Disclaimer

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