Clinical trial NCT01420224: Study of the Effects of Commercial Air Travel on the Lungs
Official title: Study of the Effects of Commercial Air Travel on Pulmonary Artery Pressure in Healthy Passengers and in a Patient With Chuvash Polycythaemia
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Healthy Volunteers
Chuvash Polycythaemia
Keywords: Air travel
Aircraft cabin hypoxia
Pulmonary artery pressure
Hypoxic pulmonary vasoconstriction
Pulmonary hypertension
Lead sponsor: University of Oxford
Sponsor class: OTHER
First posted: 2011-08-19
Enrollment: 9
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Patient with Chuvash polycythaemia recruited from previous study participants with the disease.

Brief summary: The study hypothesis is that commercial air travel causes an increase in the blood pressure in the lungs (pulmonary artery pressure) that can be clinically relevant. Portable echocardiography (heart ultrasound) now offers a non-invasive means of studying this in-flight.

Detailed description: In a commercial airliner flying at high altitude, the reduced cabin air pressure means that all passengers are exposed to slightly lowered oxygen levels ('hypoxia') equivalent to an altitude of approximately 5,000 to 8,000 ft. Although mild, this hypoxia is sufficient to stimulate some of the body's protective responses (eg changes in breathing and in hormonal secretion) and can be dangerous for passengers with heart or lung disease, who must breathe supplementary oxygen in-flight or may even be prohibited from flying because of the risks of hypoxia.

It is well known that severe hypoxia results in constriction of blood vessels in the lungs (a phenomenon called hypoxic pulmonary vasoconstriction), which in turn causes an increase in the blood pressure in the lungs ('pulmonary arterial pressure'). Unlike other physiological responses to hypoxia, this is often harmful and frequently leads to pulmonary hypertension and right heart failure (eg in some lung diseases and at high altitude). Even a modest increase in pulmonary arterial pressure could be clinically important in some airline passengers with heart/lung disease, as it may exacerbate their condition. However, it is not known whether the mild hypoxia experienced in an aircraft cabin is able to cause an increase in pulmonary artery pressure. Limited evidence suggests that it might - for example, there have been reports of passengers acutely developing new right heart failure in-flight, and data from animal studies also support this possibility.

This study aims to establish the effect of mild aircraft cabin hypoxia on pulmonary arterial pressure in healthy passengers and also in a patient with Chuvash polycythaemia. In this rare genetic disease, cellular responses to hypoxia are 'switched on' to some extent even during normoxia, causing increased red blood cell production. Affected individuals usually present with symptoms of polycythaemia in early adulthood and are typically asymptomatic following treatment with therapeutic venesection. Importantly, affected individuals have exaggerated acute hypoxic pulmonary vasoconstriction which may place them at risk of pulmonary hypertensive responses during air travel.

Eligibility criteria: For healthy volunteers:

Inclusion Criteria:

* suitable for echocardiographic measurements
* in good health

Exclusion Criteria:

* any significant medical condition

For patient with Chuvash polycythaemia:

Inclusion Criteria:

* diagnosis of Chuvash polycythaemia
* suitable for echocardiographic measurements

Exclusion Criteria:

* any other significant medical condition
* pulmonary hypertension
* uncontrolled erythrocytosis

Primary outcomes:
measure: Systolic pulmonary artery pressure
timeFrame: In-flight
Secondary outcomes:
Other outcomes:
Locations:
city: Oxford
country: United Kingdom
facility: University of Oxford
Study officials:
affiliation: University of Oxford
name: Thomas Smith, MBBS DPhil FRCA
role: PRINCIPAL_INVESTIGATOR
References: