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Biomedical subjects

S Haroun

Publications and source records attributed to S Haroun.

At least 19 recordsLinked to original sources
PubMed1992

Prediction of post-cardiopulmonary bypass cardiac output by venous oximetry.

The present study evaluates two equations for predicting the post-cardiopulmonary bypass cardiac output (CO) in 10 patients undergoing coronary artery bypass grafting. One equation is based on the relationship of CO with mixed venous oxygen saturation (SVO 2), while the second equation is based on the relationship with oxygen extraction (1 - SVO 2). Each patient served as his own control. During bypass, when the patients were normothermic and perfused with a pump flow of 2.4 L/min/m 2, the SVO 2 was monitored by an in-line Bentley oxystat Meter. Just before termination of bypass, the pump flow was decreased to 0.4 L/min/m 2 and the left atrial pressure was increased to 10-15 mmHg; the resulting SVO 2 was recorded. The post-bypass CO was predicted in every patient by the two equations. Immediately after weaning from bypass, the cardiac output was measured by thermodilution. The thermodilutional CO measurement was correlated with the CO predicted by the two equations. Correlation analysis suggests that CO prediction is more accurate and approaches the 1:1 ratio when the calculation of predicted CO is based on the relationship between cardiac output and oxygen extraction.

Adult↗
PubMed1991

The hemodynamic effects of intravenous norepinephrine versus epinephrine and phenylephrine in patients with ischemic heart disease.

The hemodynamic effects of an intravenous bolus of norepinephrine 10 micrograms, phenylephrine 100 micrograms and epinephrine 10 micrograms were investigated in 30 patients scheduled for coronary artery bypass grafting. The hemodynamic changes following norepinephrine were similar to those achieved by phenylephrine. Both drugs increased the mean blood pressure and systemic vascular resistance without any significant change of cardiac output. In contrast, epinephrine increased the mean arterial pressure and cardiac output without a significant change of systemic vascular resistance. The results suggest that intravenous norepinephrine acts similar to phenylephrine as an alpha-adrenergic agonist, while epinephrine acts predominantly as a beta-adrenergic agonist.

Adult↗
PubMed1990

Continuous venous oximetry during cardiopulmonary bypass: influence of temperature changes, perfusion flow, and hematocrit levels.

This study was performed in 11 patients undergoing cardiac surgery during cardiopulmonary bypass (CPB). A Bentley-10 oxygenator (American Bentley, Irvine, CA) was used during bypass, and 1,500 mL of Ringer's solution was used to prime the oxygenator. A perfusion flow of 2.4 L/min/m2 was used, and an equivalent flow of 100% oxygen was added to the oxygenator. The mixed venous oxygen saturation (SvO2) was monitored by continuous in-line venous oximetry using the Bentley Oxy-Stat Meter. Body temperature and SvO2 measurements were made at the venous blood port of the oxygenator. The authors investigated the correlation between SvO2 and changes of body temperature, perfusion flow, and hematocrit values. SvO2 correlated inversely, in a linear fashion, with the body temperature. The SvO2 was markedly decreased after rewarming, and was significantly affected during normothermia by changes in perfusion flow rates and hematocrit levels. An adequate SvO2 was found when the flow was greater than 2.4 L/min/m2 and the hematocrit was greater than 20%. In-line oximetry can help to optimize perfusion during CPB and to detect episodes of desaturation.

Aged↗
PubMed1989

Action of adrenergic agonists on resistance v capacitance vessels during cardiopulmonary bypass.

The peripheral vascular effects of three different adrenergic agonists were investigated in 13 patients undergoing valve replacement during cardiopulmonary bypass (CPB). The venous reservoir (RV) and mean arterial pressure (MAP) were used as indices of the changes in venous capacitance and arterial resistance, respectively, produced by the adrenergic agonists. Isoproterenol, a pure beta-adrenergic agonist, decreased both MAP and RV. Norepinephrine (NE), which activates both alpha 1- and alpha 2-receptors in humans, increased both MAP and RV, while phenylephrine (PH) a selective alpha 1-adrenergic agonist, increased only MAP with no significant change in RV. It is concluded that in humans during hypothermic CPB, beta-agonists dilate both the resistance and capacitance vessels, selective alpha 1-adrenergic agonists preferentially constrict the resistance vessels, and non-selective alpha 1- and alpha 2-adrenergic agonists constrict both the resistance and capacitance vessels.

Adult↗
PubMed1989

Effects of preoperative calcium channel and beta-adrenergic blockade on the vascular response to adrenergic agonists during cardiopulmonary bypass.

The present report compares the effects of isoproterenol (ISO), norepinephrine (NE), and phenylephrine (PH) on the mean arterial pressure (MAP) and reservoir volume (RV) during cardiopulmonary (CPB) in 16 patients undergoing coronary artery bypass grafting (CABG) who were treated preoperatively with oral nifedipine (10 to 40 mg, three times a day) and propranolol (40 to 60 mg, three times a day). The changes of RV and MAP were used as indices of the changes in venous capacitance and arterial resistance, respectively, produced by the adrenergic agonists. ISO, a beta-adrenergic agonist, decreased both MAP and RV. NE, which activates both alpha 1- and alpha 2- adrenoceptors, increased both MAP and RV, while PH, a selective alpha 1-adrenergic agonist, increased only MAP with no significant change in RV. The changes are qualitatively similar to those previously achieved in patients undergoing valve replacement who did not receive any blocker preoperatively. However, the decrease of MAP by ISO and its increase by NE were significantly less in the CABG group. It is concluded that preoperative preparation of patients undergoing CABG with beta-adrenergic blockers and calcium channel blockers can modify the effect of ISO and NE on the peripheral resistance, but they have no significant effect on the action of PH at the doses selected in this study.

Adult↗
PubMed1987

Verapamil pretreatment before aortic cross-clamping in patients undergoing coronary artery bypass graft.

In 12 of 22 patients with coronary artery disease undergoing elective coronary artery bypass graft (CABG), verapamil (0.075 mg/kg body weight) pretreatment was given on initiation of cardiopulmonary bypass (CPB) before aortic cross-clamping (ACC), whereas no verapamil was used in 10 control patients. The volume of cardioplegia solution required to achieve and maintain cardiac asystole during ACC while on CPB was not significantly different in the two groups. After the release of ACC, the energy of direct current countershock required for defibrillation, the incidence of heart block, and the need for pacemaker were not significantly different. However, defibrillation was more readily achieved by a single countershock in the verapamil group than in the control group. Also, the incidence of ST segment changes after defibrillation was significantly lower in the verapamil group, suggesting that verapamil pretreatment before ACC may potentiate the myocardial preservation achieved by the cardioplegia, and hence may decrease the incidence of ischemic changes during the critical reperfusion period.

Aorta↗