Capillary blood gas in infants with bronchiolitis: Can end-tidal capnography replace it?

OBJECTIVES: To explore the predictive ability of capillary blood gas (CBG) pCO2 for respiratory decompensation in infants aged ≤6 months with bronchiolitis admitted from the emergency department; to determine whether end-tidal CO2 (etCO2 ) capnography can serve as a less invasive substitute for CBG pCO2 .

STUDY DESIGN: This was a prospective cohort study of previously healthy infants aged ≤6 months admitted for bronchiolitis from the emergency department (ED). Initial CBG pCO2 and etCO2 capnography were obtained in the ED prior to inpatient admission. Simple logistic regression modeling was used to examine the associations of CBG pCO2 and etCO2 capnography with respiratory decompensation. Pearson's correlation measured the relationship between CBG pCO2 and etCO2 capnography.

RESULTS: Of 134 patients, 61 had respiratory decompensation. There was a significant association between CBG pCO2 and respiratory decompensation (OR = 1.07, p = 0.003), even after outlying values were excluded (OR = 1.06, p = 0.005). End tidal CO2 capnography was not significantly associated with decompensation (OR = 1.02, p = 0.17), even after outlying values were excluded (OR = 1.02, p = 0.24). There was a moderate correlation between etCO2 capnography and CBG pCO2 (r = 0.39, p < 0.001).

CONCLUSION: In infants with bronchiolitis, CBG pCO2 provides an objective measure for predicting respiratory decompensation, and a single etCO2 measurement should not replace its use.