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

Abstract

<b>Objective:</b> To investigate whether partial arterial carbon dioxide pressure (PaCO2) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) and nocturnal end-tidal CO2 (PetCO2) measurement obtained by oxycapnography, a non-invasive method, are concordant with each other. <b>Patients and methods:</b> 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 three times at night (23:00 pm, 03:00 am, 07:00 am). <b>Results:</b> 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 PaCO223:00 and PaCO207:00 levels (p=0.032). There was no significant difference between PaCO2, PetCO2, and SpO2 levels in the NMD group. The inter-class correlation coefficient between PaCO207:00 and PetCO2 results was 0.791 (95% CI: 0.533-0.923); the inter-class correlation coefficient between overnight mean PaCO2 and PetCO2 was 0.811 (95% CI:0.533 - 0.923). <b>Conclusion:</b> Our study indicates that nocturnal PetCO2 and PaCO2 levels were statistically comparable but the use of PaCO2 alone is not adequate for early diagnosis of NH in NMD. There is a need for making more restrictive definitions for NH, conducting studies with larger study populations to reach an agreement on the best definition of hypoventilation, and updating consensus guidelines.