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 (PaCO2) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) is concordant with nocturnal end-tidal CO2 (PetCO2) 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 PetCO2, oxygen saturation (SpO2), pulse rate, and respiratory rate. Arterial blood gas analysis was performed to record PaCO2 levels on three occasions at night (23: 00 pm, 03: 00 am, 07: 00 am). Results: The mean overnight PaCO2 level of the three blood gas analyses (mean PaCO2noct) was 41.78±4.69 mmHg. A significant change was observed between mean PaCO2 23: 00 and PaCO2 07: 00 levels (p=0.032). There was no significant difference between PaCO2, PetCO2, and SpO2 levels in the NMD group. The interclass correlation coefficient between PaCO2 07: 00 and PetCO2 levels was 0.791 (95% CI: 0.533-0.923); the interclass correlation coefficient between overnight mean PaCO2 and PetCO2 levels was 0.811 (95% CI: 0.533-0.923). Conclusion: Our study indicates that nocturnal PetCO2 and PaCO2 levels were statistically comparable but the use of PaCO2 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.