Value of Nocturnal Monitoring of Transcutaneous O2 and CO2 Pressures in Adults with Respiratory Failure

Publisher Website
Google Scholar
Abstract
The reliability was evaluated of the transcutaneous (t.c.) method of measurement of arterial PO2 [partial pressure of O2, PaO2] and PCO2 [partial pressure CO2, PaCO2] in adult man. In 33 simultaneous measurements of 9 normals and 12 patients with a wide range of hypoxemia, t.c. (PCO2 = 3.62 .+-. 1.29 PaCO2 .+-. 7.3 (r = 0.96) and t.c. PO2 = -11.14 .+-. 0.86 PaO2 .+-. 9.89 (r = 0.92). Recalculating t.c. PCO2 to 37.degree. C a t.c. PCO2 and PaCO2. The t.c. apparatus detects 10 and 90% O2 pressure changes with a delay of time of .apprx. 15 s and 1 min, respectively; the t.c. method is therefore not suitable for detecting changes in PaO2 caused by sleep apnea of short duration. On the contrary the t.c. method provided a useful monitoring of PaO2 and PaCO2 changes during the night in chronic obstructive pulmonary disease (COPD) and non-COPD patients. A nocturnal monitoring of t.c. PO2 and PCO2 seems: absolutely necessary in non-COPD hypoxemics, especially if total lung capacity (TLC) and/or residual volume (RV) are significantly reduced; not absolutely necessary in COPD hypoxemics, provided they have an enlarged TLC and/or a very expanded RV; advisable in intermediate situations, e.g., in COPD hypoxemics with an associated restrictive disorder caused by heart failure, congestion of pulmonary bed, parenchymal or rib cage disease, in order to establish the optimal concentration of oxygen for each patient and to avoid severe nocturnal hypoxemia without producing a dangerous rise in PaCO2.