Evaluation of a System for Transcutaneous Long-Term Capnometry

Abstract

Background: The measurement of CO₂ partial pressure (PCO₂) is of great importance. Former systems of transcutaneous capnometry combining the measurement of oxygen partial pressure (PO₂) and PCO₂ had their limitations due to skin irritations caused by the heating-up of the sensor and a short application time of 4 h. Objectives: To evaluate for the first time combined monitoring of transcutaneous PCO₂ (tcPCO₂) and oxygen saturation applying a lower temperature (sensor temperature 42°C) and a new sensor technology in healthy individuals during sleep. Methods: Twenty-nine healthy individuals [12 males, age 35.2 ± 17.0 years, body height: 170.2 ± 12.0 cm (mean ± SD), weight: 76.3 ± 15.8 kg, body mass index 26.5 ± 5.4] were monitored for more than 6 h at night with the TOSCA 500 instrument (Radiometer, Basel, Switzerland). tcPCO₂ was continuously monitored and its correlation with selective measured capillary PCO₂ values (PcapCO₂) was monitored at 0.00 and 4.00 h. Results: At 0.00 h, PcapCO₂ was 37.1 ± 5.1 mm Hg and tcPCO₂ was 43.4 ± 6.6 mm Hg (p < 0.001). At 4.00 h, PcapCO₂ was 37.0 ± 5.6 mm Hg and tcPCO₂ was 43.5 ± 5.4 mm Hg (p < 0.001). PcapCO₂ and tcPCO₂ were positively and significantly correlated (0.00 h: r = 0.5, p < 0.02 and 4.00 h: r = 0.72 and p < 0.001) at both time points. In the course of the night, there was no significant drift in the tcPCO₂ values. Conclusion: The investigated system enables stable measurement of tcPCO₂ without relevant drift in healthy individuals and does not require recalibration. tcPCO₂ is highly suitable as a measure of PcapCO₂ because the two parameters are highly correlated and there is no inconvenience to the patient.

Validity of transcutaneous PCO 2 in monitoring chronic hypoventilation treated with non-invasive ventilation

“…Using the same methodology on a limited number of patients, 4 studies found lower levels of drift [16,22,23,26]. Another study performed on 29 healthy individuals found no significant drift during continuous 4 h PtcCO 2 recordings [45].…”

Comparison of Transcutaneous and Capillary Measurement of PCO2in Hypercapnic Subjects

“…Our studies 21 are the only studies to examine transcutaneous capnography via the comparison of capillary instead of arterial blood gas measurement with P tcCO 2 . This is important because of its impact on routine clinical practice.…”

“…21 In addition, a 6-min walk test and a cycle ergometer exercise test were performed whenever possible.…”

Evaluation of a transcutaneous carbon dioxide monitor in patients with acute respiratory failure

“…These have looked at critically ill children,[15] emergency room patients with acute respiratory failure,[16] patients during cardiopulmonary exercise testing,[17] or healthy individuals. [18] Two previous studies have evaluated critically illness patients:[47] the first one[4] looked at eighteen patients, among whom, nine had hemodynamic instability treated with inotropic or vasoactive drugs; the second study[7] evaluated 69 critically ill patients admitted to the surgical intensive care unit for major surgery, multiple trauma, or septic shock. Of this group, 39 were placed on mechanical ventilation.Only three further studies have evaluated transcutaneous monitoring in patients undergoing non-invasive ventilation: the first two[1617] (with a small number of patients) had a good agreement between PaCO 2 and PtCO 2 , the third,[5] instead, reported a sub-optimal result.…”