TY - JOUR
T1 - Oxygen delivery and uptake relationships in patients with aortic stenosis
AU - Schumacker, Paul T.
AU - Soble, Jeffrey S.
AU - Feldman, Ted
PY - 1994/5
Y1 - 1994/5
N2 - Previous studies have reported finding supply-dependent O2 uptake (V̇O2) in patients with the adult respiratory distress syndrome, sepsis, chronic obstructive lung disease, sleep apnea, and other cardiopulmonary diseases. A common element among these diverse conditions is the potential to reduce systemic O2 delivery (Q̇O2 = cardiac output · arterial O2 content). The aim of the present study was to determine whether patients with aortic stenosis also exhibit increases in V̇O2 when O2 delivery is increased after valvuloplasty. Fifty-six patients were studied while breathing room air in the supine position. Expired gases for determination of O2 uptake (V̇O2 [measured]), cardiac output (thermodilution), arterial and mixed venous blood gases, and hemodynamic measurements were obtained immediately before and within 30 min after aortic valvuloplasty. After valvuloplasty, V̇O2 (measured) increased from 3.03 ± 0.51 to 3.24 ± 0.62 ml/min/kg (p < 0.0001). However, O2 extraction ratio did not change from baseline levels (32.16 ± 10.1%) after valvuloplasty (32.21 ± 8.25%, p = not significant). These results could have occurred only if O2 delivery had also increased. Accordingly, Fick-derived Q̇ and corresponding Q̇O2 (Fick) both increased significantly, suggesting the presence of O2 supply-dependent V̇O2. However, neither Q̇ (thermodilution) nor Q̇O2 (thermodilution) changed significantly, and regression of V̇O2 (measured) against Q̇O2 (thermodilution) failed to detect a relationship. We conclude that patients with aortic stenosis exhibit increases in O2 delivery and uptake after valvuloplasty, although this may or may not reflect covert tissue hypoxia. The inability to detect this relationship when V̇O2 (measured) was plotted against Q̇O2 (thermodilution) can be explained by the large measurement error in thermodilution Q̇ determinations, relative to the change in output produced by valvuloplasty.
AB - Previous studies have reported finding supply-dependent O2 uptake (V̇O2) in patients with the adult respiratory distress syndrome, sepsis, chronic obstructive lung disease, sleep apnea, and other cardiopulmonary diseases. A common element among these diverse conditions is the potential to reduce systemic O2 delivery (Q̇O2 = cardiac output · arterial O2 content). The aim of the present study was to determine whether patients with aortic stenosis also exhibit increases in V̇O2 when O2 delivery is increased after valvuloplasty. Fifty-six patients were studied while breathing room air in the supine position. Expired gases for determination of O2 uptake (V̇O2 [measured]), cardiac output (thermodilution), arterial and mixed venous blood gases, and hemodynamic measurements were obtained immediately before and within 30 min after aortic valvuloplasty. After valvuloplasty, V̇O2 (measured) increased from 3.03 ± 0.51 to 3.24 ± 0.62 ml/min/kg (p < 0.0001). However, O2 extraction ratio did not change from baseline levels (32.16 ± 10.1%) after valvuloplasty (32.21 ± 8.25%, p = not significant). These results could have occurred only if O2 delivery had also increased. Accordingly, Fick-derived Q̇ and corresponding Q̇O2 (Fick) both increased significantly, suggesting the presence of O2 supply-dependent V̇O2. However, neither Q̇ (thermodilution) nor Q̇O2 (thermodilution) changed significantly, and regression of V̇O2 (measured) against Q̇O2 (thermodilution) failed to detect a relationship. We conclude that patients with aortic stenosis exhibit increases in O2 delivery and uptake after valvuloplasty, although this may or may not reflect covert tissue hypoxia. The inability to detect this relationship when V̇O2 (measured) was plotted against Q̇O2 (thermodilution) can be explained by the large measurement error in thermodilution Q̇ determinations, relative to the change in output produced by valvuloplasty.
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U2 - 10.1164/ajrccm.149.5.8173751
DO - 10.1164/ajrccm.149.5.8173751
M3 - Article
C2 - 8173751
AN - SCOPUS:0028330113
SN - 1073-449X
VL - 149
SP - 1123
EP - 1131
JO - American journal of respiratory and critical care medicine
JF - American journal of respiratory and critical care medicine
IS - 5
ER -