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Predicting hypoxaemia during flights in children with cystic fibrosis
R M Buchdahl1, A Babiker, A Bush
1Royal Brompton & Harefield NHS Trust, Sydney Street, London SW3 6NP, UK. rbuc@easynet.co.uk
Insights
Predicting in-flight oxygen desaturation in children with cystic fibrosis is crucial. Spirometry testing before travel proved more effective than a hypoxic challenge for identifying children at risk of desaturation.
Area of Science:
- Pediatric Pulmonology
- Aerospace Medicine
- Respiratory Physiology
Background:
- Children with cystic fibrosis and chronic lung disease are at risk of oxygen desaturation during flights.
- Previous research suggested a pre-flight hypoxic challenge could predict desaturation.
- This study evaluated the predictive value of this challenge over five years.
Purpose of the Study:
- To compare the efficacy of a pre-flight hypoxic challenge versus spirometry in predicting in-flight oxygen desaturation in pediatric cystic fibrosis patients.
- To assess the sensitivity and specificity of both methods.
Main Methods:
- Eighty-seven children with cystic fibrosis underwent a pre-flight hypoxic challenge (15% oxygen inhalation) and spirometry.
- Oxygen saturation (SpO2) was monitored during tidal breathing and intercontinental flights.
- Spirometry included forced expiratory volume in 1 second (FEV1) measurements.
Main Results:
- Ten children experienced desaturation (<90% SpO2) during flight; three required oxygen.
- The hypoxic challenge predicted desaturation in only 20% of cases (sensitivity 20%, specificity 99%).
- Spirometry predicted desaturation with higher sensitivity (70%) and good specificity (96%), showing a superior area under the ROC curve (0.89 vs. 0.73).
Conclusions:
- Pre-flight spirometric testing is a more reliable predictor of in-flight oxygen desaturation in children with cystic fibrosis compared to the hypoxic challenge.
- Spirometry offers a better risk assessment for air travel in this patient population.
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 (SpO(2)) during tidal breathing of 15% oxygen in nitrogen and spirometric testing 1 month before the flight followed by SpO(2) 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 SpO(2) 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 (FEV(1)) 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.