Continuous non-invasive end-tidal CO2 monitoring in pediatric inpatients with diabetic ketoacidosis

Abstract

Introduction: Pediatric inpatients with diabetic ketoacidosis (DKA) are routinely subjected to frequent blood draws in order to closely monitor degree of acidosis and response to therapy. The typical level of acidosis monitoring is less than ideal, however, because of the high cost and invasiveness of frequent blood labs. Previous studies have validated end-tidal carbon dioxide (EtCO2) monitoring in the emergency department (ED) for varying periods of time. We extend these findings to the inpatient portion of the hospitalization during which the majority of blood tests are sent.

Methods: All patients admitted to an intermediate care unit in (InCU) a large children's hospital were fitted with an appropriately sized oral/nasal cannula capable of sensing EtCO2. Laboratory studies were obtained according to hospital clinical practice guidelines. In a retrospective analysis, EtCO2 values were correlated with serum total CO2 (stCO2), venous pH (vpH), venous pCO2 (vpCO2), and calculated bicarbonate from venous blood gas (vHCO3-).

Results: A total of 78 consecutive episodes of DKA in 72 patients aged 1-21 yr were monitored for 3-38 h with both capnography and laboratory testing, producing 334 comparisons. Initial values were as follows, reported as median (range): stCO2, 11 (4-22) mmol/L; vpH, 7.281 (6.998-7.441); vpCO2, 28.85 (9.3-43.3) mmHg; and vHCO3-, 14 (3-25) mmol/L. EtCO2 was correlated well with stCO2 (r = 0.84, p < 0.001), vHCO3- (r = 0.84, p < 0.001), and vpCO2 (r = 0.79, p < 0.001).

Conclusions: These data support the findings of previous studies limited to ED populations and suggest that non-invasive EtCO2 monitoring is a valuable and reliable tool to continuously follow acidosis in the setting of the acutely ill pediatric patient with DKA. Continuous EtCO2 monitoring offers the practitioner an early warning system for unexpected changes in acidosis that augments the utility of intermittent blood gas determinations.