Cardiac Output Assessments in Anesthetized Children: Dynamic Capnography Versus Esophageal Doppler

Abstract

BACKGROUND: The objective of this study was to compare esophageal Doppler cardiac output (COEDM) against the reference method effective pulmonary blood flow cardiac output (COEPBF), for agreement of absolute values and ability to detect change in cardiac output (CO) in pediatric surgical patients. Furthermore, the relationship between these 2 methods and noninvasive blood pressure (NIBP) parameters was evaluated. METHODS: Fifteen children American Society of Anesthesiology (ASA) I and II (median age, 8 months; median weight, 9 kg) scheduled for surgery were investigated in this prospective observational cohort study. Baseline COEPBF/COEDM/NIBP measurements were made at positive end-expiratory pressure (PEEP) 3 cm H2O. PEEP was increased to 10 cm H2O and COEPBF/COEDM/NIBP was recorded after 1 and 3 minutes. PEEP was then lowered to 3 cm H2O, and all measurements were repeated after 3 minutes. Finally, 20-µg kg−1 intravenous atropine was given with the intent to increase CO, and all measurements were recorded again after 5 minutes. Paired recordings of COEDM and COEPBF were examined for agreement and trending ability, and all parameters were analyzed for their responses to the hemodynamic challenges. RESULTS: Bias between COEDM and COEPBF (COEDM − COEPBF) was −17 mL kg−1 min−1 (limits of agreement, −67 to +33 mL kg−1 min−1) with a mean percentage error of 32% (95% confidence interval [CI], 25–37) and a concordance rate of 71% (95% CI, 63–80). The hemodynamic interventions caused by PEEP manipulations resulted in significant decrease in COEPBF absolute numbers (155 mL kg−1 min−1 [95% CI, 151–159] to 127 mL kg−1 min−1 [95% CI, 113–141]) and a corresponding relative decrease of 18% (95% CI, 14–22) 3 minutes after application of PEEP 10. No corresponding decreases were detected by COEDM. Mean arterial pressure showed a relative decrease with 5 (95% CI, 2–8) and 6% (95% CI, 2–10) 1 and 3 minutes after the application of PEEP 10, respectively. Systolic arterial pressure showed a relative decrease of 5% (95% CI, 2–10) 3 minutes after application of PEEP 10. None of the recorded parameters responded to atropine administration except for heart rate that showed a 4% relative increase (95% CI, 1–7, P = .02) 5 minutes after atropine. CONCLUSIONS: COEDM was unable to detect the reduction of CO cause 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.

Capnodynamics – noninvasive cardiac output and mixed venous oxygen saturation monitoring in children

“…The capnodynamic method for continuous cardiac output assessment has been extensively validated against a large variety of reference methods in both experimental and clinical studies (9,(27)(28)(29)(30)(31)(32)(33)(34)(35). Like most method comparison studies, the initial focus has been on relating the methods accuracy against absolute values obtained with "gold standard" reference techniques and its ability to detect change (trending ability).…”

Blood pressure and flow in pediatric anesthesia: An educational review

“…The method has shown superior performance to transthoracic and transesophageal Doppler estimation of minor to moderate changes in CO in mechanically ventilated children undergoing general surgery. 30,31 Furthermore, the capnodynamic method has been shown to adequately estimate CO pediatric animal models of pulmonary hypertension. 32 The method has the advantage of being available in nearly all intubated and mechanically ventilated subjects.…”

“…The fluctuations in alveolar carbon dioxide content and elimination are proportional to the blood flow participating in gas exchange (effective pulmonary blood flow), which in the absence of large pulmonary or intracardiac shunts represents systemic CO. The method has shown superior performance to transthoracic and transesophageal Doppler estimation of minor to moderate changes in CO in mechanically ventilated children undergoing general surgery 30,31 . Furthermore, the capnodynamic method has been shown to adequately estimate CO pediatric animal models of pulmonary hypertension 32 .…”

Capnodynamics—Measuring cardiac output via ventilation

“…Furthermore, the method is not yet tested in small neonates and premature children, situations where respiratory rate in combination with limitations in response time for mainstream capnography may interfere with the accuracy of the method 20 . Nevertheless, the technique has been clinically tested on infants down to approximately 4 kg with satisfying performance compared to various reference methods 16 …”

“…The first test of dynamic capnography for cardiac output estimation in an experimental setting was performed by Hällsjö et al 12 They Since the characteristic breathing pattern used in dynamic capnography potentially could interfere with adequate transthoracic ultrasound assessment of cardiac output, a similar study using esophageal, rather than transthoracic, Doppler as reference was performed. 16 Again, 15 mechanically ventilated infants (median age and weight 8 months and 9 kg, respectively) were subjected to changes in PEEP and given atropine to induce variations in cardiac output.…”