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Biomedical subjects

A Baraka

Publications and source records attributed to A Baraka.

At least 145 records · Page 8Linked to original sources
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

Maternal awareness and neonatal outcome after ketamine induction of anaesthesia for Caesarean section.

Ketamine was used as the sole anaesthetic during the induction-to-delivery interval in 20 full-term patients undergoing elective Caesarean section. The intravenous administration of ketamine 1.5 mg.kg-1 was followed by succinylcholine 1.5 mg.kg-1 and tracheal intubation. The mother's lungs were then ventilated using 100 per cent oxygen until the baby was delivered. Intraoperative maternal awareness was assessed by the isolated forearm technique. The Apgar scores of the newborn at one and five minutes, as well as their umbilical vein blood gases were also evaluated and correlated with the induction-to-delivery (I-D) and the uterine incision-to-delivery (U-D) intervals. In 13 patients (Group A) the I-D interval was less than 10 min and U-D interval less than 90 sec, while in seven (Group B) the I-D interval was greater than or equal to 10 min and the U-D interval greater than or equal to 90 sec. The isolated arm test was negative in all patients having an I-D interval less than 10 min, and was positive in three patients when the I-D interval exceeded ten minutes. The newborns of group A showed higher Apgar scores at one minute, as well as higher umbilical vein PO2 than was achieved in Group B. It was concluded that the technique used was not associated with maternal awareness or neonatal depression, provided that the I-D interval was less than 10 min and the U-D interval was less than 90 sec.

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↗
PubMed1990

Blood ordering habits for elective surgery: time for change.

A prospective study was carried out for 6 months to determine the efficacy of blood ordering routines for elective surgery. It was found that only 23% of procedures needed preoperative crossmatching of blood (transfusion index 'TI' greater than 0.5). There was an excessive over-ordering of blood for 77% of the operations (crossmatch/transfusion ratio greater than 2.5). In addition, the transfusion index for the latter group showed that there was no need to prepare blood preoperatively (TI less than 0.5). A transfusion tariff is worked out which abandons crossmatching for the majority of procedures (cholecystectomy, thyroidectomy and surgery for duodenal ulcer excluding gastrectomy). Instead a 'group and screen' policy is suggested.

Blood Grouping and Crossmatching↗
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↗
PubMed1989

Awareness following different techniques of general anaesthesia for caesarean section.

Using the isolated arm technique, the frequency of awareness was evaluated in 50 full-term patients undergoing elective Caesarean section under general anaesthesia. In 20 patients, anaesthesia was induced with thiopentone 4 mg kg-1, and in the other 30 patients, induction was with ketamine 1.5 mg kg-1. Following suxamethonium 1.5 mg kg-1 and tracheal intubation, anaesthesia was supplemented during the induction-delivery period in the thiopentone group with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, and with 1% halothane in 100% oxygen in the other 10 patients. In the ketamine group, the patients underwent ventilation with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, with 1% halothane in 100% in 10 patients, and with 100% oxygen only in the last 10 patients. Awareness was significantly greater after induction with thiopentone (14/20) than after ketamine (4/30). There were no significant differences in Apgar scores or umbilical vein blood-gas values in the newborns.

Anesthesia, General↗