Pediatric Critical Care Fellow St. Christopher's Hospital for Children St Christopher's Hospital for Children Philadelphia, Pennsylvania, United States
Background: The Vasoactive-Ventilation-Renal (VVR) Score has been created and validated for outcome prediction in post cardiac surgery patients. It mandates arterial measurement of partial pressure of carbon dioxide (PaCO2), either requiring continued presence of arterial catheter or repeat arterial puncture. Quantitative waveform capnography (continuous end-tidal carbon dioxide measurement - EtCO2) is routinely used to monitor ventilation in intubated patients. If interchangeable, it would allow calculation of VVR independent of arterial blood draw.
Objective: This study investigated whether EtCO2 could be used as a reliable, less invasive substitute parameter for PaCO2 in VVR calculation. It was conducted as part of the assessment of the utility of the VVR score to predict mortality in intubated, pediatric trauma patients.
Design/Methods: Independent of trauma mechanism, children aged 0-18 years admitted to our level I pediatric trauma center between January 1, 2014 and December 31, 2018 who were endotracheally intubated upon admission were included in analyses. Of 4663 registered trauma patients, 50 met inclusion criteria. Correlation between PaCO2 and EtCO2 was assessed via linear regression model with F-statistic.
Results: Median age was 3.5 years (IQR 1.75-11.25). Blunt trauma was most common (68%). Fourteen patients (28%) did not survive to hospital discharge. 137 matched observations for PaCO2 and EtCO2 were available across all four assessed time points (6, 12, 24 and 48 hours post admission). Linear regression model demonstrated a strong correlation between PaCO2 and EtCO2 based VVR (Figure 1). Findings are supported by highly significant F statistic (F=1.396 x10 , p<2.2 x 10 ) suggesting the validity of the model. In addition, R squared value of 0.99 suggests that virtually all variability of PaCO2 based VVR is accounted for using EtCO2 derived scores. Conclusion(s): EtCO2 can be used as a reliable substitute parameter for PaCO2 in VVR calculation. Our results unlock the potential for use of EtCO2 based VVR score for less invasive monitoring as well as the possibility of a continuous surveillance tool in post cardiac surgery care. Capacity of our results is limited by the retrospective nature of the study. Future, prospective studies are needed to further validate results.
Figure 1: Linear Regression Model of EtCO2 and PaCO2 based VVR
Authors/Institutions: I. Friederike Strelow, St Christopher's Hospital for Children, Philadelphia, Pennsylvania, United States; Christopher Pennell, St Christopher's Hospital for Children, Philadelphia, Pennsylvania, United States; Autumn D. Nanassy, St Christopher's Hospital for Children, Philadelphia, Pennsylvania, United States; Amit C. Misra, Children's Hospital Los Angeles, Los Angeles, California, United States; Stephen Aronoff, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, United States; Vicki Mahan, St Christopher's Hospital for Children, Philadelphia, Pennsylvania, United States