Exhaled end-tidal carbon dioxide as a predictor of lactate and pediatric sepsis

Objective: The objective of this study was to investigate the relationship between exhaled end-tidal carbon dioxide (ETCO₂) and serum lactate via nasal capnography and to assess the ability of ETCO₂ to predict disease severity in children with suspected sepsis in a pediatric emergency department. Methods: This prospective study included patients (≥ 30 days to ≤21 years of age) who presented with suspected sepsis to a tertiary pediatric emergency department. Pearson correlation coefficient was generated to measure the linear relationship between ETCO₂ and lactate. Receiver operating characteristic curves (ROC) were generated to assess the performance of ETCO₂ to predict a lactate ≥2 mmol/L and severe disease. Severe disease was defined as severe sepsis and septic shock. Results: From November 1, 2018 to March 31, 2020, 105 emergency department patients underwent evaluation for suspected sepsis. Sixty-nine patients met the inclusion criteria for the study. There was an inverse relationship between ETCO₂ and lactate with a correlation coefficient of −0.34 (p = .005). Severe disease had lower ETCO₂ (32 ± 6 mmHg, p < .001) and higher lactate (3.3 ± 1.7 mmol/L, p < .001). The area under the curve (AUC) for ETCO₂ to predict severe disease was 0.75 (95% CI 0.63, 0.86). An ETCO₂ cut off point of 30 mmHg correlated with a sensitivity of 93% and specificity of 32%. Conclusions: We observed a significant inverse relationship between ETCO2 and lactate in children presenting with suspected sepsis. A lower ETCO2 was predictive of severe disease.