Capnodynamic Cardiac Output (Dynamic capngraphy)
Cardiac output monitoring is gaining increased importance in pediatric anesthesia and intensive care.(1) Karlsson et al (2) investigated effective pulmonary blood flow (COEPBG) technique in pediatric surgical patients, compared with suprasternal two-dimensional Doppler (COSSD). COEPBF was measured continuously using the differential Fick’s principle. The method is based on the differential Fick principle and utilizes the molar balance for pulmonary carbon dioxide exchange. A total of 15 children undergoing cleft lip/palate surgery were investigated. Before the start of surgery, maneuvers that were anticipated to reduce (increase in PEEP from 3 to 10 cm H2O) and increase (atropine) CO were undertaken. A study in mechanically ventilated piglets was also undertaken under general anesthesia, measuring COEPBF and pulmonary artery (COTS) flow by ultrasonic probe as the comparator. Bias (Bland−Altman plots) and limits of agreement were assessed for effective pulmonary blood flow and COSSD or COTS. In pediatric patients (median age 8.5 months), overall bias was −8.1 (limits of agreement −82 to +66) ml kg−1 min−1, with a mean percentage error of 48% and a concordance rate of 64%. In the piglet model, overall bias was −1 (−36 to +38) ml kg−1 min−1, with a mean percentage error of 31% and a concordance rate of 95%. The authors concluded that under controlled experimental conditions, COEPBF is associated with excellent agreement and good trending ability when compared with the gold standard COTS. In the pediatric clinical setting, COEPBF performs well; by contrast, COSSD, an operator- and anatomy-dependent technology, appears less reliable than COEPBF.
In another study, Karlsson et al (3) used capnodynamic cardiac output to esophageal Doppler cardiac output (COEDM). Cardiac output changes were caused by the manipulation of PEEP. COEDM was unable to detect the reduction of CO caused by increased PEEP, whereas COEPBF and to a minimal extent, NIBP detected these changes in CO. The ability of COEPBF to react to minor reductions in CO, before noticeable changes in NIBP are seen, suggests that COEPBF may be a potentially useful tool for hemodynamic monitoring in mechanically ventilated children. (Anesth Analg 2022;134:644–52).
1. Singh Y, Villaescusa JU, da Cruz EM, et al. Recommendations for hemodynamic monitoring for critically ill children-expert consensus statement issued by the cardiovascular dynamics section of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC). Crit Care. 2020;24:620.
2. Karlsson J, Winberg P, Scarr B, et al. Validation of capnodynamic determination of cardiac output by measuring effective pulmonary blood flow: a study in anesthetized children and piglets. Br J Anaesth. 2018;121:550–558.
3. Karlsson et al. Cardiac Output Assessments in Anesthetized Children: Dynamic Capnography Versus Esophageal Doppler. Anesth Analg 2022;134:644–5.