title: Estimation of PaCO2 during exercise in children and postoperative pediatric patients with congenital heart disease.
abstract: We evaluated how Paco(2) and respiratory variables relate during and after exercise and derived a new noninvasive estimation of Paco(2) in children and postoperative patients with congenital heart disease. We randomly selected 8 subjects from each of three categorized groups from our previous studies: 15 control subjects (8 to 21 years old), 16 Fontan procedure patients (9 to 22 years old), and 13 patients after right ventricular outflow tract reconstruction (RVOTR) [7 to 21 years old], and used their respiratory variables during exercise testing to estimate Paco(2) (study 1). In a stepwise multiple regression analysis, end-tidal carbon dioxide tension (Petco(2)), age, ventilatory equivalent for carbon dioxide (minute ventilation [Ve]/carbon dioxide production [Vco(2)]), and gas exchange ratio (R) were major determinants of Paco(2) in control subjects: Paco(2) = 12.0 + 0.54 Petco(2) + 0.15 Ve/Vco(2) - 3.6 R + 0.22 age (r = 0.86). In addition to Petco(2) and Ve/Vco(2), arterial oxygen saturation and tidal volume were additional major determinants for Fontan procedure and RVOTR patients, respectively. We derived equations to predict the Paco(2) (r = 0.92 for Fontan procedure and r = 0.74 for RVOTR). These equations were applied to the remaining study subjects to estimate Paco(2) (study 2). Estimated values correlated with the measured Paco(2) (r = 0.71 to 0.86), and the mean differences for the control subjects, Fontan procedure, and RVOTR patients were - 0.1, - 0.1, and - 1.0, with limits of agreement of +/- 3.3, +/- 4.4, and +/- 3.1, respectively. Although estimated Paco(2) based on the Jones equation correlated with the measured Paco(2) in all groups, their slopes were significantly flatter than ours. Paco(2) throughout exercise testing may be estimated in control children and postoperative pediatric patients. The Jones equation should be applied with great care in pediatric subjects.
authors.affiliation: Department of Pediatrics, National Cardiovascular Center, Suita, Osaka, Japan. hohuchi@hsp.ncvc.go.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohuchi
authors.forename: Tamaki
authors.initials: T
authors.lastname: Hayashi
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamada
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Echigo
mesh_terms: D000293:Adolescent; D000328:Adult; D002245:Carbon Dioxide / Q000097:blood*; D002648:Child; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D018729:Fontan Procedure; D006330:Heart Defects, Congenital / Q000097:blood* / Q000601:surgery; D006801:Humans; D011184:Postoperative Period; D011659:Pulmonary Gas Exchange; D012126:Respiratory Dead Space / Q000502:physiology; D012189:Retrospective Studies; D013771:Tetralogy of Fallot / Q000097:blood / Q000601:surgery; D013990:Tidal Volume / Q000502:physiology; D014797:Vital Capacity / Q000502:physiology
chemical_list: D002245:Carbon Dioxide