Contribution of Transcutaneous PCO2 in Obesity Hypoventilation Syndrome

Thomas Georges; Sandrine Jaffré; Jean Morin; Agathe Delbove; Béatrice Guyomarch; Hakim Alami; Cédric Bretonnière; François-Xavier Blanc

doi:10.4187/respcare.10816

Contribution of Transcutaneous P_CO₂ in Obesity Hypoventilation Syndrome

Respir Care. 2023 Oct 17;69(1):68-75. doi: 10.4187/respcare.10816. Online ahead of print.

Authors

Thomas Georges^{1

2}, Sandrine Jaffré³, Jean Morin², Agathe Delbove⁴, Béatrice Guyomarch⁵, Hakim Alami², Cédric Bretonnière², François-Xavier Blanc²

Affiliations

¹ Respiratory Medicine Department, CHD Vendée, La Roche sur Yon, France.
² Nantes Université, Nantes University Hospital, Service de Pneumologie, L'institut du thorax, Nantes, France.
³ Nantes Université, Nantes University Hospital, Service de Pneumologie, L'institut du thorax, Nantes, France. sandrine.jaffre@chu-nantes.fr.
⁴ Intensive Care Unit, Centre Hospitalier Bretagne Atlantique, Vannes, France.
⁵ Nantes Université, Nantes University Hospital, Plateforme de Méthodologie et Biostatistique, Nantes, France.

PMID: 37848253
PMCID: PMC10753607 (available on 2025-01-01)
DOI: 10.4187/respcare.10816

Abstract

Background: More and more patients have obesity-hypoventilation syndrome (OHS) because of the increasing prevalence of obesity. The accuracy of transcutaneous P_CO₂ (P_tcCO₂ ) has recently been validated. However, no study evaluated the interest of measuring systematically nocturnal P_tcCO₂ in the follow-up of patients with OHS and home mechanical ventilation to detect residual nocturnal hypoventilation. We aimed to evaluate the contribution of nocturnal P_tcCO₂ to assess nocturnal hypoventilation compared with current routine examinations, that is, daytime arterial blood gases and nocturnal pulse oximetry.

Methods: A prospective monocentric pilot study was conducted from August 2018 to November 2019. Patients with stable OHS and who were treated with home noninvasive ventilation for at least 6 months were eligible to participate. After oral consent, we performed both diurnal arterial blood gases and combined home oximetry and capnography. The primary end point was the presence of residual nocturnal hypoventilation, defined as P_aCO₂ > 45 mm Hg or bicarbonate ≥ 27 mmol/L, S_pO₂ < 90% for ≥ 10% of the night, or P_tcCO₂ > 49 mm Hg for ≥ 10% of the night.

Results: A total of 32 subjects were included. Twenty-nine subjects with nocturnal P_tcCO₂ were analyzed. Eighteen of the 29 subjects showed residual nocturnal hypoventilation. The association of diurnal arterial blood gases and nocturnal pulse oximetry revealed nocturnal hypoventilation in only 9 subjects. Among the 19 subjects with both normal blood gases and normal nocturnal pulse oximetry, 11 had nocturnal hypoventilation with transcutaneous capnography. Only one subject presented with hypoventilation symptoms (asthenia).

Conclusions: The assessment of P_tcCO₂ in comparison with nocturnal pulse oximetry and arterial blood gases provides important information for the diagnosis of residual nocturnal hypoventilation in the subjects with OHS who were ventilated at home.

Keywords: Non-invasive ventilation; Obesity-hypoventilation syndrome; Transcutaneous PCO2.