Assessment of Nocturnal Hypoventilation by Different Methods and Definitions in Children with Neuromuscular Disease: Oxycapnography and Blood Gas Analysis

OBJECTIVE: To investigate whether partial arterial carbon dioxide pressure (PaCO(2)) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) is concordant with nocturnal end-tidal CO(2) (PetCO(2)) measurement obtained by a noninvasive method of oxycapnography in children with neuromuscular disease (NMD). METHODS: Twenty-one patients aged 6-18 years with a confirmed diagnosis of NMD were enrolled. Each patient underwent a nocturnal oxycapnography study using an orinasal probe and a pulse oximetry finger probe to record PetCO(2), oxygen saturation (SpO(2)), pulse rate, and respiratory rate. Arterial blood gas analysis was performed to record PaCO(2) levels on three occasions at night (23:00 pm, 03:00 am, 07:00 am). RESULTS: The mean overnight PaCO(2) level of the three blood gas analyses (mean PaCO(2)noct) was 41.78±4.69 mmHg. A significant change was observed between mean PaCO(2) 23:00 and PaCO(2) 07:00 levels (p=0.032). There was no significant difference between PaCO(2), PetCO(2), and SpO(2) levels in the NMD group. The interclass correlation coefficient between PaCO(2) 07:00 and PetCO(2) levels was 0.791 (95% CI: 0.533-0.923); the interclass correlation coefficient between overnight mean PaCO(2) and PetCO(2) levels was 0.811 (95% CI:0.533-0.923). CONCLUSION: Our study indicates that nocturnal PetCO(2) and PaCO(2) levels were statistically comparable but the use of PaCO(2) alone is not adequate to make an early diagnosis of NH in NMD. There is a need for making more restrictive definitions for NH, and conducting studies with larger study populations to reach an agreement on the best definition of hypoventilation, and updating consensus guidelines.