Unpredictable fluctuations in transcutaneous P(CO2) from capillary blood gas determinations

Gerald J Kost, J. L. Chow, M. Kenny

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Transcutaneous P(CO2) electrode response time was optimized by use of a new electrode filling solution composed of NaCl/NaHCO3 electrolyte buffer (100 and 20 mmol/L, respectively) in an equivolume mixture of glycerol and water. The 95% response time to a step change in P(CO2) was 49.9 ± 2.8 s (x̄ ± SD) when there was no spacer between the membrane and glass of the electrode. Use of this filling solution during monitoring of severely ill premature infants with cardiopulmonary disease allowed identification of large, unpredictable transient changes in transcutaneous p(CO2), and therefore presumably in arterial P(CO2), that occurred during capillary blood gas sampling. The changes, which occurred in 19 of 20 samplings, ranged from -1.06 to +2.53 kPa (-8 to +19 Torr). The maximum relative change observed was +29%. These results indicate that the standard protocol for capillary blood collection induces significant transient fluctuations in blood gas tensions. We believe these fluctuations decrease the reliability of capillary P(CO2) values for use in clinical management in patient populations similar to ours.

Original languageEnglish (US)
Pages (from-to)1514-1516
Number of pages3
JournalClinical Chemistry
Issue number7
StatePublished - 1982
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Biochemistry


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