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Mads Klokker and Soren Vesterhauge - Perilymphatic Fistual in Cabin Attendants:  An Incapacitating Consequence of Flying with Common Cold, Aviation, Space and Environmental Medicine, Vol 76, No.1 January 2005; 76:66-8.

A perilymphatic fistula (PLF) is an abnormal communication between the inner ear and the middle ear that leaks perilymph.  PLF is considered rare, but is known to occur during childbirth, straining, weightlifting, head trauma and diving with middle ear equalizing problems.  It has also, anecdotally, been described in connection with flying.  The symptoms are uncharacteristic vertigo and, in some cases, hearing impairment and tinnitus.  This study describes four cases of PLF during a period of 6 months in a major Scandinavian airline company employing approximately 3000 cabin attendants (CAs).  None of the cases were diagnosed at the primary health care level.  All were referred to the Aviation Medical Center for investigation.  The PLF diagnosis was based on the case history, Platform Pressure Test (a fistula test), and other vestibular tests.  Only one CA has been able to return to flying duties.  The article emphasizes the risk of flying with poor middle ear equalisation and the necessity of reminding crews and airline companies to “never fly with a common cold.”

RM Buchdahl, A Babiker, A Bush, D Cramer – Predicting hypoxaemia during flights in children with cystic fibrosis, Thorax Journal 2001; 56:877-879

Abstract

Background – We have previously suggested that it is possible to predict oxygen desaturation during flight in children with cystic fibrosis and chronic lung disease by non-invasive measurement of oxygen saturation following inhalation of 15% oxygen – the pre-flight hypoxic challenge.  This study reports on the results of measurements over 5 years.

Methods – The study comprised a pre-flight hypoxic challenge measuring oxygen saturation by finger tip pulse oximetry (Spo2) during tidal breathing of 15% oxygen in nitrogen and spirometric testing 1 month before the flight followed by Spo2 measurements during intercontinental flights to and from holidays abroad with children in wake and sleep states.

Results – Pre-flight tests were completed on 87 children with cystic fibrosis.  Desaturation of <90% occurred in 10 children at some stage during the flight, three of whom received supplementary oxygen.  Using a cut off Spo2 of 90%, the pre-flight hypoxic challenge correctly predicted desaturation in only two of these children.  The sensitivity and specificity of the pre-flight hypoxic challenge were 20% and 99%, respectively, compared with 70% and 96% for spirometric tests (using a cut off for forced expiratory volume in 1 second (FEV1) of <50% predicted).  Overall, pre-flight spirometric tests were a better predictor of desaturation during flight with the area under the Receiver Operating Characteristic (ROC) curve of 0.89 compared with 0.73 for the hypoxic challenge test.

Conclusions – In this group of subjects pre-flight spirometric testing was a better predictor of desaturation during flight than the pre-flight hypoxic challenge.

R Buchdahl, A Bush, S Ward, D Cramer, Pre-flight hypoxic challenge in infants and young children with respiratory disease, Thorax BMJ Journals 2004;59: 1000-1003

Modern aircraft flying at high altitude are cabin pressurised to an atmospheric partial pressure of up to 8,000ft (2348 metres), equivalent to breathing approximately 15% oxygen.  This may expose individuals with cardiorespiratory disease to the risk of developing hypoxia.  In 2002, the British Thoracic Society (BTS) issued recommendations for passengers with respiratory diseases who are planning to fly.  These recommendations included the use of a hypoxic challenge test in children with a history of respiratory disease too young to undergo conventional lung function tests.  While pre-flight hypoxic challenge tests have been evaluated in older children and adults with respiratory disease, there are few data on hypoxic responses in infants and young children with respiratory disease although one study has observed profound desaturation in a small number of healthy infants while asleep.

In the last 6 years we have tested 20 children under 5 years of age with a history of chronic pulmonary disease in early infancy.  At our institution fitness to fly testing using 15% oxygen has been performed as a routine test in older children and adults with respiratory disease for some years, so formal ethical approval was not sought for this study.  Children were exposed to a hypoxic challenge with 15% oxygen, while sitting on the lap of a carer in a whole body plethysmograph (body box).  Oxygen saturation was monitored by pulse oximetry (Spo2) using a probe attached to the child’s finger.  After measuring Spo2 of the child in air, nitrogen was passed into the body box at approximately 50 l/min to dilute the oxygen content of the air to 15% over a period of 5 minutes.  Oxygen and carbon dioxide concentrations were measured via continuous flow sampling using a Centronics 200 MGA mass spectrometer.  The Spo2 could take up to approximately 20 minutes to reach a stable value (constant over 2-3 minutes).  In none of the tests did the carbon dioxide concentration in the body exceed 0.5%.  In nine cases oxygen was subsequently administered via nasal cannulae to restore the fall in Spo2 to the original (air) value so that this flow of oxygen could then be recommended during the flight.  However, because of lack of data on the range of the normal desaturation response and the clinical significance, advice was not always consistent (table 1, p 1001).  No child was oxygen dependent at the time of the test although four children were receiving nocturnal or intermittent supplementary oxygen.  Four children were tested a second time for subsequent flights (cases 1,3, 4 and 5).  Eight of the 20 children desaturated below 90% in 15% oxygen, six of whom had normal (>95%) saturations at rest in air.  Outcome information was obtained from all seven families who had been advised to take supplementary oxygen (table 1, p 1001).  Case 2 was notable for the profound desaturation episode that occurred during the flight.  Information regarding the outcome of flights for children for whom supplementary oxygen was not advised was incomplete.  Three cases did not fly and seven were lost to follow up.

We conclude that some children with a history of chronic pulmonary disease in early infancy may have normal oxygen saturations in room air but desaturate significantly below 90% when exposed to a 15% oxygen hypoxic challenge.  These children may be at risk of hypoxia when flying at altitude.  This uncontrolled observational series suggests that such infants should be advised to take supplementary oxygen during the flight.  The hypoxic challenge test is a simple and practical test and may be performed in any lung function laboratory with a whole body plethysmograph, a source of nitrogen, and a means of measuring oxygen.  As carbon dioxide concentrations do not reach clinically significant levels, oxygen concentrations in the body box could be measured with a conventional oxygen monitor.  Further studies are required to evaluate fully the hypoxic challenge test in young children.  Spo2 measurements during flight on subjects and healthy control children are needed.  Measurements should be undertaken both in the awake and sleep states because there is evidence that Spo2 falls in some older children with cystic fibrosis while asleep during flight and in normal infants at sea level.

Alexandra Mangili, Mark A Gendreau – Transmission of infectious diseases during commercial air travel The Lancet, Vol 365, March 12, 2005

Because of the increasing ease and affordability of air travel and mobility of people, airborne, food-borne, vector-borne, and zoonotic infectious diseases transmitted during commercial air travel are an important public health issue.  Heightened fear of bioterrorism agents has caused health officials to re-examine the potential of these agents to be spread by air travel.  The severe acute respiratory syndrome outbreak of 2002 showed how air travel can have an important role in the rapid spread of newly emerging infections and could potentially even start pandemics.  In addition to the flight crew, public health officials and health care professionals have an important role in the management of infectious diseases transmitted on airlines and should be familiar with guidelines provided by local and international authorities.

Introduction

Over 1 billion passengers travel by air annually; 50 million of these travel to the developing world.  Although infrequently reported and very difficult to assess accurately, there is a risk of disease transmission during commercial air travel and this risk has become the focus of heightened attention.  The growing mobility of people and popularity of airline transportation has amplified the potential for disease to be transmitted to passengers not only during but also before and after flights.  Here, we review knowledge about transmission of infectious disease associated with commercial air travel, with particular emphasis on transmission within the aircraft passenger cabin.

Conclusions

Commercial airlines are a suitable environment for the spread of pathogens carried by passengers or crew.  The environmental control system used in commercial aircraft seems to restrict the spread of airborne pathogens, and the perceived risk is greater than the actual risk.  Transmission of infectious diseases probably happens more frequently than reported for various reasons, including reporting bias and the fact that most diseases have a longer incubation period than air travel.  Important questions include:  what factors affect the transmission of infectious diseases within the aircraft cabin?  How effective are the ventilation systems used within commercial aircraft with regard to emerging infections?  Further assessment of risk thorugh mathematical modelling is needed and will provide insight into disease transmission within the aircraft cabin as well as control of outbreaks of different diseases.

The International Health Regulations adopted worldwide in 1969 to limit the international spread of disease are being revised to provide a means for immediate notification of all disease outbreaks of international importance.  Outbreaks will be characterised by clinical syndrome rather than specific diagnosis to expedite reporting.  These new regulations and continued vigilance by countries, health authorities, airlines, and passengers will keep to a minimum but not eliminate the risk of disease spread by aircraft.  The aviation industry and medical community should educate the general public on health issues related to air travel and infection control.

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