Nocturnal oximetry and transcutaneous carbon dioxide in home-ventilated neuromuscular patients.

BACKGROUND

Pulse oximetry alone has been suggested to determine which patients on home mechanical ventilation (MV) require further investigation of nocturnal gas exchange. In patients with neuromuscular diseases, alveolar hypoventilation (AH) is rarely accompanied with ventilation-perfusion ratio heterogeneity, and, therefore, oximetry may be less sensitive for detecting AH than in patients with lung disease.

OBJECTIVE

To determine whether pulse oximetry (S(pO(2))) and transcutaneous carbon dioxide (P(tcCO(2))) during the same night were interchangeable or complementary for assessing home MV efficiency in patients with neuromuscular diseases.

METHODS

Data were collected retrospectively from the charts of 58 patients with chronic neuromuscular respiratory failure receiving follow-up at a home MV unit. S(pO(2)) and P(tcCO(2)) were recorded during a 1-night hospital stay as part of standard patient care. We compared AH detection rates by P(tcCO(2)), S(pO(2)), and both.

RESULTS

AH was detected based on P(tcCO(2)) alone in 24 (41%) patients, and based on S(pO(2)) alone with 3 different cutoffs in 3 (5%), 8 (14%), and 13 (22%) patients, respectively. Using both P(tcCO(2)) and S(pO(2)) showed AH in 25 (43%) patients.

CONCLUSIONS

Pulse oximetry alone is not sufficient to exclude AH when assessing home MV efficiency in patients with neuromuscular diseases. Both P(tcCO(2)) and S(pO(2)) should be recorded overnight as the first-line investigation in this population.