Diagnostic accuracy of capnography during high‐frequency ventilation in neonatal intensive care units

Summary Background and Objective High‐frequency ventilation (HFV) is a powerful tool for CO 2 elimination, and thus requires careful monitoring of CO 2 . Our aim was to assess the diagnostic accuracy (correlation, agreement, and trending) of continuous distal capnography (dCap) with PaCO 2 in infants ventilated with HFV. Design This was a prospective, observational, multicenter study. dCap was compared with simultaneous PaCO 2 (“gold standard”) drawn from indwelling arterial line for patient care in term and preterm infants ventilated with HFV. dCap was obtained via the side‐port of a double‐lumen endotracheal‐tube by a Microstream capnograph with specially designed software for HFV. Results Twenty‐four infants participated in the study (median [range] gestational age [GA]: 26.8 [23.6–38.6] weeks). Analysis included 332 measurements. dCap was in correlation (r = 0.70, P  < 0.001) but with less than adequate agreement (mean difference ± SD of the differences: −11.7 ± 10.3 mmHg) with PaCO 2 . Comparable findings were found in the subgroup of infants <1,000 g (n = 240 measurements). Correlations were maintained in severe lung disease. Changes in dCap and in PaCO 2 for consecutive measurements within each patient were correlated (r = 0.63, P  < 0.001). Area under the receiver operating curves (ROC) for dCap to detect high (>60 mmHg) or low (<30 mmHg) PaCO 2 was 0.83 (CI: 0.76–0.90) and 0.88 (CI: 0.79–0.97), respectively; P  < 0.001. Conclusions Our prospective study suggests that continuous dCap in infants ventilated with HFV may be helpful for trends and alarm for unsafe levels of PaCO 2 . dCap is only a complimentary tool and cannot replace PaCO 2 sampling because the agreement between these measurements was less than adequate. Pediatr Pulmonol. 2016;51:510–516 . © 2015 Wiley Periodicals, Inc.