RESPIRATORY INFECTION

Longer term follow up of aerobic capacity in children affected by severe acute respiratory syndrome (SARS)

C C W Yu¹, A M Li¹, R C H So², A McManus³, P C Ng¹, W Chu⁴, D Chan¹, F Cheng¹, W K Chiu⁵, C W Leung⁶, Y S Yau⁷, K W Mo⁸, E M C Wong⁹, A Y K Cheung⁹, T F Leung¹, R Y T Sung¹, T F Fok¹

¹ Department of Paediatrics, The Chinese University of Hong Kong, Shatin, Hong Kong
² Sports Institute, Hong Kong Sports Development Board, Hong Kong
³ Institute of Human Performance, The University of Hong Kong, Hong Kong
⁴ Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong, Shatin, Hong Kong
⁵ Department of Paediatrics and Adolescent Medicine, United Christian Hospital, Hong Kong
⁶ Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong
⁷ Department of Paediatrics and Adolescent Medicine, Queen Elizabeth Hospital, Hong Kong
⁸ Department of Paediatrics and Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
⁹ Centre for Epidemiology and Biostatistics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong

Correspondence to:
Dr A M Li
Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong; albertmli{at}cuhk.edu.hk

Background: A study was undertaken to investigate the aerobic capacity and pulmonary function of children 6 and 15 months after the diagnosis of severe acute respiratory syndrome (SARS).

Methods: Thirty four patients of mean age 14.7 years completed both pulmonary function and maximal aerobic capacity tests at 6 months. All had normal clinical examination and were asymptomatic. Their exercise responses were compared with a group of healthy controls. Complete data were collected on 27 of the original 34 cases at 15 months.

Results: Compared with normal controls, the patient group had significantly lower absolute and mass related peak oxygen consumption (peak V^·O₂ (p<0.01)), higher ventilatory equivalent for oxygen (p<0.01), lower oxygen pulse (p<0.01), and a lower oxygen uptake efficiency slope (p<0.01) at 6 months. This impairment was unexpected and out of proportion with the degree of lung function abnormality. Residual high resolution computed tomography of thorax (HRCT) abnormalities were present in 14 patients. Those with abnormal HRCT findings had significantly lower mass related peak V^·O₂ than subjects with normal radiology (p<0.01). Absolute and mass related peak V^·O₂ in the patient group remained impaired at 15 months despite normalisation of lung function in all patients.

Conclusions: The mechanism for the reduced aerobic capacity in children following SARS is not fully understood, but it is probably a consequence of impaired perfusion to the lungs at peak exercise and deconditioning.

Abbreviations: FEV₁, forced expiratory volume in 1 second; FEF_25–75, mid forced expiratory flow; FRC, functional residual capacity; FVC, forced vital capacity; HR, heart rate; OUES, oxygen uptake efficiency slope; PETO₂, end tidal oxygen partial pressure; PETCO₂, end tidal carbon dioxide partial pressure; PFT, pulmonary function test; RER, respiratory exchange ratio; RR, respiratory rate; TLC, total lung capacity; TLCO, carbon monoxide transfer factor; VAT, ventilatory anaerobic threshold; V^·E, minute ventilation; V^·O₂, oxygen consumption; V^·E/V^·O₂, ventilatory equivalent for oxygen; V^·E/V^·CO₂, ventilatory equivalent for carbon dioxide

Keywords: aerobic capacity; severe acute respiratory syndrome; children

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