Nocturnal end-tidal P(CO2) to detect apnoeas and hypopnoeas in sleep-disordered breathing

Publisher Website
Google Scholar
Abstract
End-tidal P(CO2), (P(ETCO2)) during the night was measured. The P(ETCO2) signal was obtained by introducing a cannula through the nose into the nasopharygeal cavity. The usefulness of this method to identify nocturnal hypoventilation was studied in 29 patients with chronic obstructive pulmonary disease (COPD) with and without O2 supplementation. The results showed that 27 patients with COPD developed 67 nocturnal O2 desaturations which were all accompanied by raised P(ETCO2). During O2 therapy in all COPD patients nocturnal episodes with increased P(ETCO2) occurred. Furthermore, the detection of nocturnal apnoeas and hypopnoeas was assessed in 19 subjects who were referred to the sleep laboratory for snoring and daytime sleepiness. In this group episodes of disordered breathing could easily be assessed. The P(ETCO2) signal was especially useful to identify hypopnoeas that were accompanied by only small dips in S(aO2) (< 3%). It is concluded that P(ETCO2) measurement is useful in the detection of hypoventilation during sleep in COPD patients, especially when they receive supplemental O2. P(ETCO2) recording detects obstructive apnoeas and hypopnoeas and is especially helpful to identify hypopnoeas which are accompanied by only small dips in O2 saturation.