Abnormal End-Tidal PO2 and PCO2 at the Anaerobic Threshold Correlate Well With Impaired Exercise Gas Exchange in Patients With Left Ventricular Dysfunction

Abstract

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp n resting normal subjects at sealevel, alveolar PO2 and PCO2 are approximately 100 mmHg and 40 mmHg, respectively. In patients with pulmonary vascular occlusive disease, there is regional hypoperfusion relative to ventilation. This is reflected in an increased physiological dead space ventilation, due to an uneven ventilation -perfusion (V/Q) relationship, that is, high V/Q mismatch. Consequently, endtidal PCO2 (PETCO2) is reduced and end-tidal PO2 (PETO2) is increased. 1 Patients with left ventricular (LV) dysfunction also have high V/Q mismatch because of reduced pulmonary blood flow despite adequate ventilation. 2,3 Thus, in these patients, PETO2 must be higher and PETCO2 must be lower, according to the severity of LV dysfunction.In the present study, we hypothesized that in patients with LV dysfunction, PETO2 and PETCO2 measured during exercise may be better correlated with the severity of the cardiopulmonary dysfunction than that at rest. In order to test this hypothesis, we measured PETCO2 and PETO2 both at rest, at anaerobic threshold (AT) and at peak exercise. We then correlated these variables with indices of cardiopulmonary function during exercise, 4 in patients with LV dysfunction. Methods SubjectsThe subjects were 38 consecutive cardiac patients who performed exercise testing with respiratory gas analysis at the Cardiovascular Institute between January 2007 and December Background: The aim of the present study was to compare the end-tidal O2 pressure (PETO2) to end-tidal CO2 pressure (PETCO2) in cardiac patients during rest and during 2 states of exercise: at anaerobic threshold (AT) and at peak. The purpose was to see which metabolic state, PETO2 or PETCO2, best correlated with exercise limitation. I

Clinical Significance of the Presence of Oscillatory Breathing Both at Rest and During Exercise in Cardiac Patients

“…17,18) The hypo-perfusion to the lung caused by reduced pulmonary blood flow in patients with left ventricular dysfunction exacerbates the V/Q mismatch (high V/Q), leading to progressively lower PETCO2. 1,19,20) The lower peak VO2, higher VE-VCO2 slope, and lower PETCO2 observed in the group C patients of the present study suggest that the cardiac dysfunction was more advanced in group C than in groups A and B. Mechanisms of oscillatory breathing: OB observed at rest or at low levels of exercise sometimes disappears during moderate-to-heavy exercise.…”

Clinical Significance of a Spiral Phenomenon in the Plot of CO2 Output Versus O2 Uptake During Exercise in Cardiac Patients

“…8,9 In patients with left ventricular dysfunction, the hypoperfusion to the lung caused by reduced pulmonary blood flow exacerbates the V/Q mismatch (high V/Q), leading to progressively lesser PETCO 2 as the cardiac disease worsens. 1,10,11 The lesser peak VO 2 , greater VEeVCO 2 slope, and lesser PETCO 2 observed in patients with the spiral phenomenon suggest that the cardiopulmonary dysfunction is more advanced in these patients than in the patients without the spiral phenomenon.…”

Adrenergic Receptor Polymorphism and Maximal Exercise Capacity after Orthotopic Heart Transplantation

“…Association of peak VO 2 with demographic and clinical parameters, or AR SNPs was tested using univariate regression analysis with peak VO 2 as the dependent variable. Peak VO 2 was expressed as the percentage of the predicted value (% predicted), which is already adjusted for age, BMI and gender [ 22 ]. Thus, these three co-variables were not included in the univariate and multivariate analysis.…”