Effects of epidural block with lignocaine and lignocaine-adrenaline on umbilical artery velocity wave ratios

Article Abstract:

The flow of blood through arteries can be assessed by Doppler ultrasound, which uses high frequency sound to monitor the behavior of fluids. Doppler assessments of the blood flow through the placenta, the organ of fetal nutrition, can tell whether the circulation through the placenta is adequate. If the blood flow through the placenta is met with resistance, the blood supply to the fetus is compromised. To see if the umbilical artery blood flow velocity is affected by the epidural anesthesia lignocaine (lidocaine), given with or without adrenaline, 24 women in early active labor were studied. Fifteen women received eight milliliters of lignocaine alone and 16 others received a combination of lignocaine and adrenaline (40 micrograms). The A/B ratios (the ratio of the highest systolic to the low lowest diastolic blood flow velocity; an index of blood vessel resistance) were calculated. All the fetuses receiving lignocaine alone had decreased A/B ratios, regardless of how high the initial A/B ratio was. The results were similar for the fetuses receiving lignocaine and adrenaline combined who had normal A/B ratios at the start. However, all six fetuses that had high A/B ratios at the onset who then received the combined lignocaine and adrenaline injection had a subsequent increase in their A/B ratio as well as transient decrease in heart rate. It is thought that the smallest amount of adrenaline, a drug that constricts blood vessels, can compromise the blood flow velocity through the placenta. It is concluded that when the umbilical artery blood flow encounters resistance, combined adrenaline and lignocaine for epidural anesthesia can reduce the blood flow further, increasing stress experienced by the fetus. (Consumer Summary produced by Reliance Medical Information, Inc.)

Usage, Blood flow, Blood flow measurement, Fetus, Epinephrine, Doppler ultrasonography, Xylocaine, Umbilical arteries

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Haemodynamic changes in gestational proteinuric hypertension: the effects of rapid volume expansion and vasodilator therapy

Article Abstract:

Preeclampsia of pregnancy, characterized by edema, high blood pressure and protein in the urine, is potentially life threatening. There is controversy about whether cardiac output and vascular resistance are different in women with preeclampsia than in healthy pregnant women. To determine cardiac output the Swan-Ganz thermodilution hemodynamic catheter can be used safely with pregnant patients. To obtain baseline values, forces influencing blood flow should be evaluated in patients with preeclampsia before any treatment is initiated. Previous studies have usually been on patients who have already begun treatment regimens for preeclampsia. The effects of volume expansion and dihydrazaline on untreated preeclamptic patients, with and without prior blood volume expansion, were examined. Before treatment patients had low pulmonary capillary wedge pressure (PCP), low cardiac index (CI) and high systemic vascular resistance (VR). After volume expansion the PCP and CI increased, the SVR decreased but the blood pressure (BP) did not change. Adding dihydrazaline caused a decrease in PCP, an increase in CI, and a decrease in SVR and blood pressure. It was concluded that in preeclampsia patients with a low CI, infusion of a small volume of fluid restored cardiac output and was associated with a decrease in vascular resistance. These effects may benefit uterine and placental blood flow before the use of vasodilators.

Laws, regulations and rules, Drug therapy, Hemodynamics, Vascular resistance, Preeclampsia, Pregnancy, Complications of, Pregnancy complications

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Haemodynamic changes associated with caesarean section under epidural anaesthesia

Article Abstract:

Many cesarean sections are performed using epidural anesthesia, the injection of an anesthetic into the dura layer in the lower region of the spine, allowing the patient to remain awake. Although this type of anesthesia is known to lower blood pressure, its effect on the force of blood circulation is not understood. Cardiac output, the amount of blood leaving the heart per minute, was measured using echocardiograms and ultrasound. Maternal hemodynamics during cesarean delivery under epidural anesthesia changed insignificantly; results were similar to vaginal delivery.

Research, Cesarean section

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