Non-Invasive (Transcutaneous) Monitoring of PCO₂ (TcPCO₂) in Older Adults

Abstract

Background: Transcutaneous measurements of arterial blood gases (ABG) may decrease the need for repeated arterial puncture in older patients treated for acute cardiac or pulmonary disorders. However, age-related changes in skin perfusion, metabolism, or thickness may alter the validity of the technique. Objective: To analyse the agreement between transcutaneous and arterial measurement of PaO₂ and PaCO₂ in older adults. Design: Prospective descriptive study performed in the intermediate-care unit of a geriatric university hospital and a pulmonary rehabilitation centre. Methods: 40 patients, aged 82.5 ± 8 years (66–97), hemodynamically stable, without vasopressor treatment, underwent simultaneous measurement of arterial blood gases (ABG) and transcutaneous CO₂ (TcPCO₂) and O₂ (TcPO₂) with a Radiometer TINA TCM3^® capnograph, and a probe T° set at 43°C. Results: Correlation between PaCO₂ and TcPCO₂ was high (r² = 0.86) with a low bias (–0.1 mm Hg) and limits of agreement quite compatible with clinical use: (8.3; –8.5 mm Hg). The probe was well tolerated without any cutaneous lesion even after prolonged recordings (up to 8 h). Conversely, although TcPO₂ and PaO₂ were significantly correlated, the variability around the regression line precludes the use of transcutaneous measurements for monitoring PaO₂in a clinical setting. Conclusion: In older subjects, TcPCO₂ (but not TcPO₂) measurements are reliable when repeated assessment of ABG is warranted.

Transcutaneous Measurement of Carbon Dioxide Tension During Extended Monitoring: Evaluation of Accuracy and Stability, and an Algorithm for Correcting Calibration Drift

“…4,[13][14][15][16][17][18] The reasons for the observed differences between P aCO 2 and P tcCO 2 have previously been reviewed. 19 However, we would attest that the aim of continuous CO 2 measurement during extended sleep monitoring is to detect sleep-related changes that suggest the presence or adequate control of hypoventilation, rather than as a direct measure of P aCO 2 per se (ie, monitoring changes during sleep, rather than measuring absolute values), so noninvasive devices that can detect change over an extended monitoring period with sufficient accuracy and minimal artifactual drift have substantial clinical utility.…”

Combined Use of Transcutaneous and End-Tidal Measures of Carbon Dioxide to Predict PCO2 during General Anaesthesia in Adults

“…Previous studies [5][6][7] [16][17][18]. Bland-Altman analysis [19] was applied to assess the mean bias and limits of agreement (LOA) (± 2 standard deviation of bias) of PaCO 2 and PtcCO 2 , PaCO 2 and PetCO 2 , PaCO 2 and Pet_ tcCO 2 .…”

“…Monitoring the partial pressure of carbon dioxide (PCO 2 ) is an essential means of assessing alveolar ventilation in patients during anesthesia, procedural sedation and emergency care [1][2][3][4][5][6]. Although the arterial blood gas(ABG) measurement of PCO 2 (PaCO 2 ) is regarded as the gold standard technique for PCO 2 assessments [7][8][9], it is an invasive and painful method that requires arterial blood gas analysis.…”

Patient-controlled sedation in procedural care

“…With increasing age, the more keratinised the dermis becomes, and the greater the gradient becomes between arterial and transcutaneous measured levels of oxygen. On the other hand, CO 2 is highly soluble and age does not have that high of an impact on reliability; thus, with correct placement of the sensor, P tc CO 2 , collected with TCM3-TINA, the monitoring has been held as accurate [91][92][93][94]. This regimen for surveillance provides cardiovascular data together with data on respiration and oxygenation.…”