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Updated: May 20, 2026

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
[Transcutaneous P(CO2) (TcP(CO2)) reflects Pa(CO2) of previous 1 or 2 minutes]
Toshimichi Kuzuta1, Masayuki Kamide, Sohei Kagawa
1Department of Anesthesia, Atsugi City Hospital, Atsugi 243-8588.
Background:
TcP(CO2) has been known to have delayed response compared with Pa(CO2).
Methods:
We examined the degree of response delay in human adults. TOSCA500 (Radiometer) was used to measure TcP(CO2). Arterial blood was withdrawn every 1 minute for 20 times. Pa(CO2) was measured with Bayer348 blood gas analyzer. TcP(CO2) value was recorded simultaneously.
Results:
TcP(CO2) values which are forwarded 0, 1, 2, 3 and 4 minutes are examined against Pa(CO2) by means of Bland and Altman analysis. Means of the difference in TcP(CO2) and Pa(CO2) are 0.9 mmHg, +0.9 mmHg, +1.0 mmHg, + 1.0 mmHg, + 1.0 mmHg and 2 SD are +/- 7.1 mmHg, +/- 6.2 mmHg, +/- 6.2 mmHg, +/- 7.2 mmHg, +/- 8.2 mmHg, respectively (N=105).
Conclusions:
In human adults values of TcP(CO2) measured by TOSCA500 are 1 or 2 minutes late compared with values of Pa(CO2) and considered to be a good monitor of Pa(CO2).
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