Arterial versus end-tidal carbon dioxide levels in children with congenital heart disease: a prospective cohort study in patients undergoing pulmonary catheterization

Abstract

Capnography has been the standard in the operating room for a long time now. When variable amounts of intrapulmonary shunt and intracardiac shunt are taken into account, arterial carbon dioxide (CO₂) and end-tidal CO₂ typically match rather well. The gap between arterial and end-tidal CO₂ widens in patients with cardiopulmonary disorders. The current study sought to determine how arterial and end-tidal CO₂ correlated with each other and with hemoglobin saturation both before and after pulmonary catheterization in a pediatric population with congenital heart disease.

Methods: Fifty-seven children with congenital heart disease who underwent cardiopulmonary catheterization between March 2018 and April 2019 were included in a prospective cohort study at Children's Medical Center. Arterial and end-tidal CO₂, and hemodynamic variables were assessed prior to the catheterization procedure. Then the patients underwent catheterization, and before being extubated, these variables were again assessed and compared to the baseline levels.

Results: End-tidal CO₂ increased significantly in cyanotic patients following the catheterization procedure, and the difference between arterial and end-tidal CO₂ decreased significantly. End-tidal CO₂, arterial CO₂, and their difference did not significantly change in non-cyanotic patients following the catheterization procedure. End-tidal and arterial CO₂ were not significantly correlated in cyanotic patients (r=0.411, P=0.128), but they were correlated after the catheterization procedure (r=0.617, P=0.014).

Conclusions: End-tidal CO₂ can estimate arterial CO₂ in non-cyanotic patients reasonably. End-tidal CO₂ cannot be used to estimate arterial CO₂ in cyanotic patients since there is no association. After cardiac defect correction, end-tidal CO₂ can be a reliable predictor of arterial CO₂.

Keywords: congenital heart disease; end-tidal CO2; pulmonary catheterization.

Figure 1

Frequency of underlying diseases. AS, aortic stenosis; ASD, atrial septal defect; AVSD, atrioventricular septal defect; CoA, coarctation of the aorta; PA, pulmonary atresia; PDA, patent ductus arteriosus; PS, pulmonary stenosis; TGA, transposition of the great arteries; ToF, tetralogy of Fallot; VSD, ventricular septal defect.

Figure 2

Frequency of each surgical treatment type. Device removal: stent removal. ASD, atrial septal defect; PDA, patent ductus arteriosus; RPA, right pulmonary artery.