P79 Children with complex congenital heart disease: who needs a pre-flight hypoxic challenge test?. (15th November 2017)

• Record Type: Journal Article
• Authors: Naqvi, N; Doughty, VL; Starling, L; Franklin, R; Ward, S; Daubeney, PEF; Balfour-Lynn, IM
• Is Part Of: Thorax. Volume 72(2017)Supplement 3
• Page Start: A126
• Page End: A126
• Publication Date: 2017-11-15
• Subjects: Chest -- Diseases -- Periodicals; Thorax; Chest -- Diseases; Periodicals; Periodicals; 617.54
• DOI: 10.1136/thoraxjnl-2017-210983.221
• Languages: English
• ISSNs: 0040-6376

Abstract

Abstract : Introduction: Commercial airplanes fly with an equivalent cabin FiO2 of 0.15 leading to reduced oxygen saturation (SpO2 ) in passengers. Although guidelines exist, the evidence-base for recommending supplemental O2 when flying in children with complex congenital heart disease (CHD) is practically non-existent. We conducted hypoxic challenge tests (HCT) to determine which children need a pre-flight assessment. Methods: Children<16 years with complex CHD were recruited; exclusions were SpO2 <75%; pulmonary hypertension; oxygen requirement; or concomitant respiratory disease. Children had a standard HCT in a sealed body plethysmograph with FiO2 of 0.15. We measured SpO2, pulse rate, transcutaneous CO2 (PtcCO2 ), corrected QT interval (QTc), and total Hb by co-oximetry (SpHb). Supplemental O2 was given (which meant a 'failed' test) if (1) children with baseline SpO2 95%–100% desaturated to 85%, (2) or baseline SpO2 85%–94% desaturated to 15% of their baseline; (3) or baseline SpO2 75%–84% desaturated to 70%. Results: There were 68 children, mean age 3.3 years (range 10 weeks to 14.5 years); 53% were boys. Grouping by normal (≥95%) vs abnormal baseline SpO2 (75%–94%), both groups had a significant fall in SpO2 (p<0.0001). 3/38 (8%) children failed with normal baseline SpO2 vs 5/32 (16%) with abnormal baseline (non-significant difference). In terms of cardiac status, both groups had a significant fall in SpO2 (p<0.0001); however in those with no residual for potential R-L shunt 0/27 failed vs those with residual potential R-L shunt or who had not undergone repair or who had palliative surgery in whom 8/41 (20%) failed (p<0.02). PtcCO2 did not change significantly ( i.e ., no-one hyperventilated to compensate for hypoxia); pulse rate and QTc were not different between groups, and unaffected by the hypoxic state. Conclusions: This is the first evidence to help inform which children with CHD need a pre-flight HCT. We suggest all children with residual potential R-L shunt or who have not undergone repair or who have only had palliative surgery should be tested (as 20% are expected to need supplemental O2 ), whereas those with no potential for R-L shunt need not be. Baseline SpO2 does not help predict who will need supplemental O2 when flying.