Assessing fitness to fly in young infants and children

Pre-Flight Hypoxemia Challenge Testing in Bronchopulmonary Dysplasia

BACKGROUND AND OBJECTIVES

Former premature infants with bronchopulmonary dysplasia (BPD) are at risk for hypoxemia during air travel, but it is unclear until what age. We aimed to determine pass rates for high altitude simulation testing (HAST) by age in children with BPD and identify risks for failure.

METHODS

Retrospective, observational analysis of HAST in children with BPD at Boston Children's Hospital, using interval censoring to estimate the time-to-event curve of first pass. Curves were stratified by neonatal risk factors. Pass was considered lowest Spo2 ≥ 90%, or ≥94% for subjects with ongoing pulmonary hypertension (PH).

RESULTS

Ninety four HAST studies were analyzed from 63 BPD subjects; 59 studies (63%) were passed. At 3 months corrected gestational age (CGA), 50% of subjects had passed; at 6 months CGA, 67% has passed; at 12 and 18 months CGA, 72% had passed; and at 24 months CGA, 85% had passed. Neonatal factors associated with delayed time-to-pass included postnatal corticosteroid use, respiratory support at NICU discharge, and tracheostomy. BPD infants who did not require respiratory support at 36 weeks were likely to pass (91%) at 6 months CGA. At 24 months, children least likely to pass included those with a history of PH (63%) and those discharged from the NICU with oxygen or respiratory support (71%).

CONCLUSIONS

Children with BPD on respiratory support at 36 weeks should be considered for preflight hypoxemia challenges through at least 24 months CGA, and longer if they had PH or went home from NICU on respiratory support.

Ventilatory support at home for children: A joint position paper from the Thoracic Society of Australia and New Zealand/Australasian Sleep Association

The goal of this position paper on ventilatory support at home for children is to provide expert consensus from Australia and New Zealand on optimal care for children requiring ventilatory support at home, both non-invasive and invasive. It was compiled by members of the Thoracic Society of Australia and New Zealand (TSANZ) and the Australasian Sleep Association (ASA). This document provides recommendations to support the development of improved services for Australian and New Zealand children who require long-term ventilatory support. Issues relevant to providers of equipment and areas of research need are highlighted.

Physiology and Predictors of Impaired Gas Exchange in Infants with Bronchopulmonary Dysplasia

Rationale: A sensitive outcome measure for infants with bronchopulmonary dysplasia would facilitate clinical benchmarking and enhance epidemiologic understanding, evaluation of clinical interventions, and outcome prediction.Objectives: Noninvasive assessment of pulmonary gas exchange in preterm infants with and without bronchopulmonary dysplasia to grade disease severity and to identify determinants of impaired gas exchange.Methods: This is a prospective observational study in very preterm infants. Inspired oxygen partial pressure (Pi_O2) was decreased stepwise to achieve oxygen saturation as measured by pulse oximetry (Sp_O2) that decreased from 95% to 86%. Right shift, V⋅a/Q⋅, and right-left shunt were derived from the resulting Sp_O2 versus Pi_O2 curve and compared with current disease severity classification. Potential determinants of shift, V⋅a/Q⋅, and shunt were identified using principal components analysis and multiple linear regression.Measurements and Main Results: A total of 219 infants with median (interquartile range) gestation of 28 weeks and 0 days (26 weeks and 0 days to 29 weeks and 0 days) had a valid study at 35 weeks and 4 days (34 weeks and 1 day to 39 weeks and 3 days) of postmenstrual age. Shift increased and V⋅a/Q⋅ decreased as severity of bronchopulmonary dysplasia increased. Infants with moderate-severe disease also had increased shunt. Extent of impaired gas exchange overlapped between severity groups. Infants requiring mechanical support but no supplemental oxygen at 36 weeks' postmenstrual age had similar values of shift, V⋅a/Q⋅, and shunt to preterm infants without bronchopulmonary dysplasia. Lower gestation and increased duration of invasive ventilation independently predicted increased shift, decreased V⋅a/Q⋅, and increased shunt. Shift was the most sensitive and specific index of the severity of bronchopulmonary dysplasia.Conclusions: Most infants with bronchopulmonary dysplasia have impaired oxygenation quantified by a simple, sensitive bedside test. Shift of the Sp_O2/Pi_O2 curve may be useful for prediction and measurement of preterm infant respiratory outcomes.

Hypoxic Challenge Test for airflight in children with respiratory disease

During airflight, cabins are pressurised to 8000ft (2438m) leading to an effective FiO₂ of 0.15. This leads to a fall in oxygen saturation in all passengers, and especially those with underlying lung disease. The hypoxic challenge test using a body plethysmograph can predict a need for supplemental oxygen during airflight, and the process is described.

Hypoxia Challenge Testing in Neonates for Fitness to Fly

BACKGROUND

Preflight hypoxia challenge testing (HCT) in a body plethysmograph has previously been done only on infants >3 months of corrected gestational age (CGA). This study aims to determine the earliest fit-to-fly age by testing neonates <1 week old.

METHODS

A prospective observational study was carried out on 3 groups of infants: healthy term infants ≤7 days old, preterm infants (≥34 weeks CGA) 2 to 3 days before discharge, and preterm infants with bronchopulmonary dysplasia (BPD). HCT was conducted using a body plethysmograph with a 15% fraction of inspired oxygen. The oxygen saturation (Spo2) test fail point was <85%.

RESULTS

Twenty-four term (mean CGA 40 weeks), 62 preterm (37 weeks), and 23 preterm with BPD (39.5 weeks) infants were tested. One term infant (4.2%) and 12 preterm infants without BPD (19.4%) failed. Sixteen (69.3%) preterm infants with BPD failed (P < .001), with a median drop in Spo2 of 16%. At 39 weeks CGA, neither preterm infants without BPD nor term infants had an Spo2 <85%. However, 7 of 12 term infants with BPD failed the HCT.

CONCLUSIONS

Term and preterm infants without BPD born at >39 weeks CGA do not appear to be likely to desaturate during a preflight HCT and so can be deemed fit to fly according to current British Thoracic Society Guidelines.

Air travel and the risks of hypoxia in children

In infants and children with chronic respiratory disease, hypoxia is a potential risk of aircraft travel. Although guidelines have been published to assist clinicians in assessing an individual's fitness to fly, they are not wholly evidence based. In addition, most evidence relates to adults with chronic obstructive pulmonary disease and thus cannot be extrapolated to children and infants. This review summarises the current literature as it applies to infants and children potentially at risk during air travel. Current evidence suggests that the gold standard for assessing fitness to fly, the hypoxia flight simulation test, may not be accurate in predicting in flight hypoxia in infants and children with respiratory disease. Further research is needed to determine the best methods of assessing safety of flight in infants and children.

Definition of Cutoff Values for the Hypoxia Test Used for Preflight Testing in Young Children With Neonatal Chronic Lung Disease

BACKGROUND

The hypoxia test can be performed to identify potential hypoxia that might occur in an at-risk individual during air travel. In 2004, the British Thoracic Society increased the hypoxia test cutoff guideline from 85 to 90% in young children. The aim of this study was to investigate how well the cutoff values of 85% and 90% discriminated between healthy children and those with neonatal chronic lung disease (nCLD).

METHODS

We performed a prospective, interventional study in young children with nCLD who no longer required supplemental oxygen and healthy control subjects. A hypoxia test (involving the administration of 14% oxygen for 20 min) was performed in all children, and the nadir in pulse oximetric saturation (Spo(2)) recorded.

RESULTS

Hypoxia test results were obtained in 34 healthy children and 35 children with a history of nCLD. Baseline Spo(2) in room air was unable to predict which children would "fail" the hypoxia test. In those children < 2 years of age, applying a cutoff value of 90% resulted in 12 of 24 healthy children and 14 of 23 nCLD children failing the hypoxia test (p = 0.56), whereas a cutoff value of 85% was more discriminating, with only 1 of 24 healthy children and 6 of 23 nCLD children failing the hypoxia test (p = 0.048).

CONCLUSION

In the present study, using a hypoxia test limit of 90% did not discriminate between healthy children and those with nCLD. A cutoff value of 85% may be more appropriate in this patient group. The clinical relevance of fitness to fly testing in young children remains to be determined.

Is this baby fit to fly? Hypoxia in aeroplanes

During air flight, cabin pressurisation results in a reduced fraction of inspired oxygen to 0.15. Healthy children desaturate by around 4% and remain asymptomatic. However children under the age of 1 year are more susceptible to hypoxia, especially if they were born preterm, and even more so if they are survivors of chronic neonatal lung disease. Pre-flight testing with a 'fitness to fly' test is available in some tertiary respiratory centres. The British Thoracic Society 2004 guideline currently recommends supplemental oxygen be given if the child's oxygen saturation falls below 90% during the test, although 85% may be a more appropriate cut off level.