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.