Accuracy of a point-of-care blood gas analyzer in gastric tonometry measurements of intramucosal pH (pHi) and P(CO2) gap.
OBJECTIVE
We assessed the accuracy of a point-of-care blood gas analyzer in providing data from saline samples obtained by gastrointestinal tonometry (Tonometrics Catheter; Tonometrics Division, Instrumentarium, Helsinki, Finland) for the calculation of intramucosal pH (pHi) and the P(CO)(2) gap (intramucosal P(CO)(2) - Pa(CO)(2)).


METHODS
We compared the point-of-care analyzer (Opti; AVL Medical Instruments, Schaffhausen, Switzerland; "Opt") with a conventional analyzer (Compact 2 AVL Medical Instruments, Schaffhausen; "Elect") in a clinical study (Elect being taking as the standard). In an in vitro study, P(CO)(2) data of tonometer saline (Pr(CO)(2)) from Opt and Elect were compared with P(CO)(2) data from a continuous air tonometer (Tonocap Tonometrics Division, Instrumentarium) for a bottle containing a mixed P(CO)(2) gas. Data were evaluated by the Bland-Altman method.


RESULTS
In the clinical study, the bias (B) and precision (P) were: B = 0.223 and P = 0.056 for pHi, B = -14.0 and P = 2.43 (mmHg) for Pr(CO)(2), and B = -16.7 and P = 2.6 (mmHg) for the P(CO)(2) gap ( n = 27). In the in vitro study, the bias between the two values (Pr(CO)(2) and bottle P(CO)(2)) was -1.98 mmHg and precision was 1.23 mmHg for Elect, but for Opt, these values were -22.09 mmHg and 3.15 mmHg, respectively ( n = 18).


CONCLUSIONS
Opt is not suitable for measuring pHi and the P(CO)(2) gap because it does not provide an accurate P(CO)(2) for tonometry saline.
Division of Emergency Medicine, Kagoshima University Hospital, Kagoshima, Japan.
Hiroshi
H
Dohgomori
Kazuhiro
K
Arikawa
Yuichi
Y
Kanmura
D001784:Blood Gas Analysis / Q000295:instrumentation*; D002245:Carbon Dioxide / Q000032:analysis*; D005753:Gastric Mucosa / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008365:Manometry / Q000295:instrumentation*; D010313:Partial Pressure; D019095:Point-of-Care Systems; D015203:Reproducibility of Results
D002245:Carbon Dioxide