Transcutaneous Carbon Dioxide Monitoring During Apnea Testing for Determination of Neurologic Death in Children: A Retrospective Case Series*

Abstract

Objectives: Determination of neurologic death in children is a clinical diagnosis based on absence of neurologic function with irreversible coma and apnea. Apnea testing during determination of neurologic death assesses spontaneous respiration when Paco 2 increases to greater than or equal to 60 and greater than or equal to 20 mm Hg above pre-apneic baseline. The utility of transcutaneous carbon dioxide measurements during apnea testing in children is unknown. We seek to determine the degree of correlation between paired transcutaneous carbon dioxide and Paco 2 values during apnea testing for determination of neurologic death. Design: Single-center, retrospective case series. Setting: Twenty-eight bed PICU in a 259-bed, tertiary care, referral center. Patients: Children 0–18 years old undergoing determination of neurologic death between May 2017 and December 2018. Interventions: None. Measurements and Main Results: Primary outcomes were paired transcutaneous carbon dioxide and Paco 2 values obtained during determination of neurologic death. Primary analyses included Pearson correlation coefficient, Bland-Altman bias and limits of agreement, and comparative statistics. Descriptive data included demographics, admission diagnoses, hemodynamics, Vasoactive Inotropic Scores, and arterial blood gas measurement. Eight children underwent 15 determination of neurologic death examinations resulting in 31 paired transcutaneous carbon dioxide and Paco 2 values for study. Transcutaneous carbon dioxide and Paco 2 correlated well (r = 0.94; p < 0.01). Bias between transcutaneous carbon dioxide and Paco 2 was –3.29 ± 7.14 mm Hg. Differences in means did not correlate with Vasoactive Inotropic Score (r = 0.2) or patient temperature (r = 0.11). Receiver operator characteristic curve of transcutaneous carbon dioxide after 3–10 minutes of apnea to discriminate positive apnea testing by the standard of Paco 2 yielded an area under the curve of 0.91 and threshold of greater than or equal to 64 mm Hg (sensitivity, 91.7%; specificity, 100%; positive predictive value, 100%; negative predictive value, 92.3%; accuracy, 95.9%). Conclusions: During apnea testing for determination of neurologic death in children, noninvasive transcutaneous carbon dioxide monitoring demonstrated high correlation, accuracy, and minimal bias when compared with Paco 2. Further validation is required before any recommendation to replace Paco 2 with noninvasive transcutaneous carbon dioxide monitoring can be proposed. However, concurrent transcutaneous carbon dioxide data may limit unnecessary apnea time and associated hemodynamic instability or respiratory decompensation by approximating goal arterial blood sampling to document target Paco 2.

Accuracy and clinical application of transcutaneous carbon dioxide monitoring in patients with sepsis

“…Consistent with the results of most previous studies [14] ! [15] , PtcCO2 was in good agreement with PaCO2 in gold standard arterial blood gas analysis in septic patients, and partial pressures are overestimated with transcutaneous compared with arterial samples in our research. The conventionally cited clinically acceptable agreement between PtcCO2 and PaCO2 is 7.5 mm Hg (or 1 kPa) [17] .…”