Original contribution
Transcutaneous monitoring of partial pressure of carbon dioxide in the elderly patient: a prospective, clinical comparison with end-tidal monitoring

https://doi.org/10.1016/j.jclinane.2006.02.007Get rights and content

Abstract

Study Objective

To evaluate the accuracy and precision of estimation of partial pressure of carbon dioxide (Paco2) using end-tidal or transcutaneous CO2 (TcPco2) measurements during mechanical ventilation in the elderly patient.

Design

A prospective, observational study was conducted.

Settings

The study was done in the anesthesia department of a university hospital.

Patients

Seventeen anesthetized, mechanically ventilated patients older than 60 years were studied.

Interventions and Measurements

During standard sevoflurane anesthesia, and after proper calibration and an equilibration time of 30 minutes with stable hemodynamic and respiratory variables, arterial (Paco2), end-tidal (Petco2), and transcutaneous (TcPco2) CO2 partial pressures were determined. In each patient, 1 to 5 sample sets (Paco2, Petco2, and TcPco2) were obtained.

Main Results

A total of 45 sample sets were obtained from the patients studied. The Paco2 values ranged between 21 and 58 mm Hg. The Paco2 − Petco2 tension gradient was 6 ± 5 mmHg (95% confidence interval, −3 to 16 mmHg), whereas the Paco2 − TcPco2 tension gradient was 2 ± 4 mmHg (95% confidence interval, −6 to 9 mmHg) (P = 0.0005). The absolute value of the difference between Paco2 and Petco2 was 3 mm Hg or less in 7 of 45 sample sets (15%), whereas the absolute value of the difference between Paco2 and TcPco2 was 3 mm Hg or less in 21 of 45 sample sets (46%) (P = 0.003). Linear regression analysis for TcPco2 versus Paco2 showed a slope of 0.84 (r2 = 0.73), whereas the linear regression analysis for Petco2 versus Paco2 showed a slope of 0.54 (r2 = 0.50).

Conclusion

Transcutaneous monitoring of CO2 partial pressure gives a more accurate estimation of arterial CO2 partial pressure than does Petco2 monitoring.

Introduction

Adequacy of ventilation during spontaneous and mechanical ventilation is usually evaluated by estimating carbon dioxide partial pressure in the arterial blood (Paco2). The gold standard for Paco2 monitoring is still based on arterial blood gas sampling; however, this approach requires an invasive procedure and provides only intermittent estimates of what is a continuously changing value. Measurement of end-tidal CO2 (Petco2) is widely used in clinical practice in the anesthetized patient [1], [2]. However, sampling errors and patient-related factors known to affect the ventilation-perfusion ratio markedly affect the accuracy of Petco2 in estimating arterial partial pressure, such as obstructive lung disease (chronic obstructive pulmonary disease [COPD]), smoking habit, patient positioning, and age [3].

Transcutaneous carbon dioxide (TcPco2) measurement is a new, noninvasive system using a modified Stow-Severinghaus pH-sensitive glass electrode applied to the ear lobe. This noninvasive method has been shown to have a good correlation with arterial CO2 values in children [4], [5] and hemodynamic stable adults [6], [7], [8], and potentially has several relevant applications for noninvasive monitoring of adequacy of ventilation in different clinical settings. However, little information is available in the literature about its accuracy in the elderly patient.

To obtain more information on TcPco2 monitoring in mechanically ventilated elderly patients, we conducted this prospective investigation to evaluate the accuracy and mean bias of estimation of Paco2 by using end-tidal and transcutaneous measurement of partial pressure of CO2 in mechanically ventilated, anesthetized patients older than 60 years.

Section snippets

Materials and methods

With University of Parma Ethical Committee approval and written patient consent, we prospectively included in the study 17 consecutive patients older than 60 years who were to receive general anesthesia for general surgery. Patients with a smoking habit and those with severe cardiac or respiratory disease (ASA physical status >III) were excluded from the study.

General anesthesia was induced with fentanyl (one μg/kg), propofol (2 mg/kg), and cisatracurium (0.2 mg/kg); the trachea was then

Results

The cohort of the study included 17 mechanically ventilated, anesthetized patients undergoing general surgery. Anthropometric characteristics, including MAP and HR at baseline and before measurement recording, as well as body temperature, are shown in Table 1. None of the study patients received any vasoactive drug during the study period, and hemodynamic variables were always within 20% of baseline values.

Two to 5 sample sets (Paco2, Petco2, and TcPco2) were obtained from the 17 patients for a

Discussion

The availability of a simple, continuous, and noninvasive method of CO2 monitoring may represent a very useful tool for daily practitioners, especially in nonintubated patients. End-tidal CO2 measurement is routinely used in mechanically ventilated patients, and, with some modification, its use has been reported with success in the nonintubated patient [2], [10], [11]. However, several mechanical and physiologic factors may affect the correlation between Paco2 and Petco2, such as sampling

References (15)

  • J. Griffin et al.

    Comparison of end-tidal and transcutaneous measures of carbon dioxide during general anaesthesia in severely obese adults

    Br J Anaesth

    (2003)
  • A. Cuvelier et al.

    Limitations of transcutaneous carbon dioxide measurements for assessing long-term mechanical ventilation

    Chest

    (2005)
  • R. Whitesell et al.

    Relationship between arterial and peak expired carbon-dioxide pressure during anesthesia and factors influencing the difference

    Anesth Analg

    (1981)
  • A. Casati et al.

    Accuracy of end-tidal carbon dioxide monitoring using the NBP-75 microstream capnometer. A study in intubated ventilated and spontaneously breathing nonintubated patients

    Eur J Anaesthesiol

    (2000)
  • A. Casati et al.

    Arterial to end tidal carbon dioxide gradient and physiological dead space monitoring during general anaesthesia: effect of patients position

    Minerva Anestesiol

    (1997)
  • J.D. Tobias et al.

    Noninvasive monitoring of carbon dioxide during respiratory failure in toddlers and infants: end-tidal vs transcutaneous carbon dioxide

    Anesth Analg

    (1997)
  • M.A. Nosovitch et al.

    Noninvasive intraoperative monitoring of carbon dioxide in children: end-tidal versus transcutaneous techniques

    Pediatr Anaesth

    (2002)
There are more references available in the full text version of this article.

Cited by (33)

  • Efficacy of high-flow nasal oxygenation compared with tracheal intubation for oxygenation during laryngeal microsurgery: a randomised non-inferiority study

    2022, British Journal of Anaesthesia
    Citation Excerpt :

    However, assessment of hypercarbia by arterial blood gas analysis and obtaining Paco2 is not always feasible in clinical practice. As an alternative, transcutaneous CO2 monitoring enables continuous and noninvasive measurement of CO2 accumulation, providing acceptable agreement with the measure of Paco2.11,18 Moreover, transcutaneous CO2 monitoring does not induce patient discomfort, arterial injury or infection, or time delay to determine the CO2 accumulation.

  • Transcutaneous monitoring as a replacement for arterial PCO <inf>2</inf> monitoring during nocturnal non-invasive ventilation

    2011, Respiratory Medicine
    Citation Excerpt :

    PetCO2 monitoring is known to have limitations in parenchymal lung disease and, importantly, also in the case of air leakage around the mask or via mouth, which regularly occurs in NPPV patients.3,7,15,17,20,22,23 In contrast, PtcCO2-monitoring is independent from both air leakage and the underlying disease, and has been shown to be more reliable than PetCO2 monitoring in different conditions.24–27 An important limitation of PtcCO2-monitoring is the reported occurrence of technical PtcCO2 drifts, which can be particularly momentous if monitoring is performed over a period of several hours or throughout the whole night.5,17

  • Critical Monitoring Issues for Surgery Performed in a Non-hospital Setting

    2009, Perioperative Nursing Clinics
    Citation Excerpt :

    Because of varying (a-ET) PCO2 in some patients, transcutaneous monitoring of PCO2 has been used as an alternative to ETCO2 monitoring. In one study of 17 elderly patients, transcutaneous monitoring of PCO2 provided a more accurate estimation of arterial CO2 partial pressure than PETCO2 monitoring.37 At the time of this writing, transcutaneous PCO2 monitoring is not yet widely available, and the role of this modality for monitoring in the OOR environment has yet to be defined.

  • Understanding sleep-disordered breathing through mathematical modelling

    2009, Sleep Medicine Reviews
    Citation Excerpt :

    The CO2 content can be estimated at the alveolar CO2 level from the expired end-tidal partial pressure using nasal-prongs (EtCO2), or at the peripheral level as the amount of CO2 that diffuses through the skin using transcutaneous sensor (TcCO2). Comparative studies of these two non-invasive techniques have demonstrated that TcCO2 enables accurate estimation of the arterial partial pressure of CO2 (PaCO2).58,59 Because of its non-invasive nature, TcCO2 measurements have been used, e.g., for nocturnal monitoring of patients.60

  • Respiratory Monitoring Equipment and Detection of Respiratory Events

    2009, Sleep Medicine Clinics
    Citation Excerpt :

    The measured value then should be normalized for the temperature. Depending on the technology that had been used, studies suggest that the measurement of transcutaneous CO2 has a better correlation with the measurement of PaCO2 than with the measurement of end tidal CO2 during wakefulness.16,17 This technique, however, has not been widely used in polysomnography.

  • Critical Monitoring Issues Outside the Operating Room

    2009, Anesthesiology Clinics
    Citation Excerpt :

    Because of varying (a-ET) PCO2 in some patients, transcutaneous monitoring of PCO2 has been used as an alternative to ETCO2 monitoring. In one study of 17 elderly patients, transcutaneous monitoring of PCO2 provided a more accurate estimation of arterial CO2 partial pressure than PETCO2 monitoring.37 At the time of this writing, transcutaneous PCO2 monitoring is not yet widely available, and the role of this modality for monitoring in the OOR environment has yet to be defined.

View all citing articles on Scopus

None of the authors had any economic relationship with the SenTech Company, Lausanne, Switzerland.

View full text