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Biomedical subjects

F M James

Publications and source records attributed to F M James.

At least 37 records · Page 2Linked to original sources
PubMed1980

Vascular and uterine responses to dobutamine and dopamine in the gravid ewe.

Dopamine, a naturally occurring catecholamine precursor of norepinephrine, has been used in the treatment of cardiogenic shock. Following intravenous administation it increases cardiac output, blood pressure, and renal blood flow. Dobutamine is a directly acting inotropic agent which increases myocardial contractility without significantly changing blood pressure. This study was devised to compare the effects of these two drugs on uterine blood flow (UBF), uterine tonus (UT), mean arterial blood pressure (MAP), and heart rate (HR). Chronically instrumented pregnant ewes near term were infused with differet concentrations of dopamine and dobutamine while HR, MAP, UT and UBF were recorded continuously. Dopamine produced a decrease in UBF and an increase in MAP and UT while the HR response was variable. Dobutamine administration resulted in a marked increase in HR and a decrease in UBF, while MAP and UT remained essentially unchanged. Uterine vascular resistance increased with both drugs during high-dosage administration, but the rise was more pronounced following dopamine infusion. Since dobutamine exhibits less alpha-adrenergic activity than dopamine this drug would seem to be preferred when an inotropic agent is required for treatment of the pregnant patient.

Animals↗
PubMed1980

Effects of nitroglycerin and nitroprusside on the uterine vasculature of gravid ewes.

The effects of nitroglycerin (TNG) and sodium nitroprusside (SNP) on mean aortic pressure (MAP), uterine blood flow (UBF), uterine vascular conductance (UVC), and pulse rate (PR) were compared when the two agents were infused to prevent and treat hypertension induced by norepinephrine (NE) in gravid ewes. When infused alone, TNG, 19 microgram/kg/min, decreased MAP 19 per cent and increased PR 33 per cent from control values (P less than 0.05), but did not significantly change UBF or UVC. In comparison, SNP, 3 microgram/kg/min, decreased MAP 20 per cent and increased PR 43 per cent (P less than 0.05), and did not significantly change UBF or UVC. When given alone, four successive 2-min infusions of NE produced dose-related increase in MAP and decreases in UBF, UVC, and PR; values were significantly different from control with the two higher doses of NE. Although MAP, UBF, and UVC were still significantly changed from control levels when NE was given in the presence of the above infusions of TNG or SNP, MAP was lower and UBF and UVC were higher compared with when NE was given alone (P less than 0.05). When given to control hypertension induced by a continuous infusion of NE, TNG or SNP produced uterine vasodilatation and significantly increased UBF. Nitroglycerin and SNP were equally effective in counteracting the maternal hypertension and antagonizing the uterine vascular effect of NE. It is concluded that TNG and SNP counteract uterine vasoconstriction resulting from alpha-adrenergic stimulation and do not produce a shunt of blood flow away from the uterine vasculature when used to control hypertension in gravid ewes.

Animals↗
PubMed1980

Chloroprocaine vs. bupivacaine for lumbar epidural analgesia for elective cesarean section.

The incidence and degree of hypotension, time to establish surgical analgesia, and several other maternal and fetal variables were studied when 2-chloroprocaine, 3 per cent, and bupivacaine, 0.5 per cent, were used for epidural analgesia in 30 women undergoing elective cesarean section. Surgical analgesia occurred 8 min sooner (P less than 0.001) with chloroprocaine (14 +/- 1 min) than with bupivacaine (22 +/- 2 min). Blood pressure values were significantly lower with chloroprocaine than with bupivacaine during the 18--to-32 min interval after local anesthetic injection, while pulse rates were higher (P less than 0.05) at 18, 20, and 22 min. Hypotension necessitating treatment with ephedrine occurred in 33 per cent of chloroprocaine-treated subjects, compared with 13 per cent of those receiving bupivacaine. Newborn outcome was excellent in both groups, as reflected by umbilical vessel blood-gas values, times to sustained respiration, and 5-min Apgar scores. The authors conclude that chloroprocaine disturbs maternal cardiovascular status more than does bupivacaine when used for cesarean section epidural analgesia. However, chloroprocaine can be employed safely in normal pregnancies if maternal hypotension is corrected rapidly.

Analgesia↗
PubMed1977

Lumbar epidural analgesia for labor and delivery of twins.

In this study we examined the effects on mother and infants of epidural analgesia for labor and delivery of twins. Fourteen women with twins received lumbar epidural analgesia. Maternal radial artery and umbilical vessel blood-gas and acid-base measurements together with Apgar scores were determined. Resulting values were compared to those of women receiving epidural analgesia for labor and delivery of one infant. Apgar scores and blood-gas values for first twins were virtually the same as for singleton controls. Our small series confirms the problem of second-twin compromise, but this was minimal and was more pronounced in nonvertex presentations, as would be expected. We believe there is much to recommend lumber epidural analgesia for labor and delivery of twins, and that it is a safe form of analgesia in this situation.

Acid-Base Equilibrium↗