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.
Dohgomori
Hiroshi
H
Division of Emergency Medicine, Kagoshima University Hospital, Kagoshima, Japan.
Arikawa
Kazuhiro
K
Kanmura
Yuichi
Y
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