Oxygen Therapy in Acute Coronary Syndrome
Oxygen Therapy in Acute Coronary Syndrome
In addition to the clinical efficacy of oxygen therapy in patients with MI, its cardiovascular and haemodynamic effects have been studied (Table 2). Most studies suggest that oxygen does not have beneficial haemodynamic effects and is even harmful. In normoxaemic patients (SaO2 >90%) with MI, oxygen therapy decreases CO and stroke volume (SV) and raises systemic vascular resistance (SVR). Notably in hypoxaemic patients with MI, oxygen therapy increased CO. A separate study showed that the administration of 100% oxygen in patients with coronary artery disease (CAD) resulted in an increase of lactate production presumably due to decreased coronary flow.
In contrast, in healthy subjects oxygen therapy increased SVR, with no change in other haemodynamic parameters.
A recent imaging study evaluated CO, SV, and calculated LV perfusion by MRI in healthy volunteers who were treated with oxygen. Oxygen therapy caused a significant 23% decline in LV perfusion. Similarly, CO decreased by 10% due to a decrease in the heart rate, with no significant changes in SV.
Haemodynamic Effects of Oxygen Therapy
In addition to the clinical efficacy of oxygen therapy in patients with MI, its cardiovascular and haemodynamic effects have been studied (Table 2). Most studies suggest that oxygen does not have beneficial haemodynamic effects and is even harmful. In normoxaemic patients (SaO2 >90%) with MI, oxygen therapy decreases CO and stroke volume (SV) and raises systemic vascular resistance (SVR). Notably in hypoxaemic patients with MI, oxygen therapy increased CO. A separate study showed that the administration of 100% oxygen in patients with coronary artery disease (CAD) resulted in an increase of lactate production presumably due to decreased coronary flow.
In contrast, in healthy subjects oxygen therapy increased SVR, with no change in other haemodynamic parameters.
A recent imaging study evaluated CO, SV, and calculated LV perfusion by MRI in healthy volunteers who were treated with oxygen. Oxygen therapy caused a significant 23% decline in LV perfusion. Similarly, CO decreased by 10% due to a decrease in the heart rate, with no significant changes in SV.
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