Epidural analgesia for labor and vaginal delivery.
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Anesthesia, Epidural↗
Biomedical subjects
T G Cheek
Publications and source records attributed to T G Cheek.
Term human fetal umbilical vein oxygen content, placental weight, and maternal blood pressure.
The relationship of umbilical venous oxygen content to placental weight and mean maternal arterial blood pressure was investigated in 38 normal nonlaboring subjects undergoing elective cesarean section at 38.4 +/- 0.2 weeks (mean +/- SEM). In 14 subjects breathing room air, umbilical vein oxygen content was found to be a function of the lowest mean maternal arterial blood pressure (r = 0.48, P = 0.04), but not to placental weight. In 24 subjects breathing supplemental oxygen, umbilical vein oxygen content was not related to placental weight or lowest mean maternal arterial blood pressure. Fetuses attached to placentas less than 396 g had a higher hemoglobin concentration than fetuses attached to placentas greater than 396 g. This suggests the possibility of chronic in utero hypoxemia in human fetuses attached to small placentas.
Adult↗
Succinylcholine pharmacodynamics in peripartum patients.
Serum cholinesterase activity decreases 30% during pregnancy and remains depressed during the postpartum period. However, succinylcholine recovery is not prolonged in term-pregnant patients. This contrasts with results obtained in other patients with decreased serum cholinesterase activity. To better understand this paradox, the authors compared serum cholinesterase activity and recovery from succinylcholine, 1 mg/kg, in nonpregnant (with and without oral contraceptive use), in term-pregnant, and in postpartum patients. Serum cholinesterase activity was lower in both term-pregnant (3.66 +/- 0.39 U/ml, means +/- SE) and postpartum (2.84 +/- 0.35 U/ml) patients than in nonpregnant patients not taking oral contraceptives (5.01 +/- 0.33 U/ml, P less than 0.05). Cholinesterase activity in postpartum patients also was significantly lower than in nonpregnant patients taking oral contraceptives (4.81 +/- 0.63, P less than 0.05). In contrast, the time to 25% twitch-height recovery did not differ between term-pregnant (470 +/- 56 s) and nonpregnant patients taking (499 +/- 29 s) or not taking (501 +/- 21 s) oral contraceptives, but was significantly increased in postpartum patients (685 +/- 22 s, P less than 0.001). The similar duration of action of succinylcholine in term-pregnant patients (with decreased serum cholinesterase activities) and nonpregnant patients may be related to the increased volume of distribution of succinylcholine at term.
Adult↗
Estimation of human fetal-placental unit metabolic rate by application of the Bohr principle.
The Bohr Principle via continuous indirect calorimetry was used to estimate human fetal-placental unit metabolic rate in 12 normal women undergoing elective caesarean section under continuous lumbar epidural anaesthesia. Maternal oxygen consumption decreased after umbilical cord clamping and after placental removal. Fetal-placental unit oxygen consumption was 10.7 +/- 1.3 ml/min per kg (mean +/- SEM). Fetal oxygen consumption was 6.8 +/- 1.4 ml/min per kg. Placental oxygen consumption was 37 +/- 12 ml/min per kg. Fetal-placental unit carbon dioxide production was 9.2 +/- 1.2 ml/min per kg. These mean values agree favourably with measurements of uterine and fetal metabolism from other mammalian species. Maternal minute ventilation decreased with removal of the fetal-placental unit, and this decrease was found to be linearly related to the fetal-placental unit carbon dioxide production.
Adult↗
Effects of immediately initiating an epidural infusion in the combined spinal and epidural technique in nulliparous parturients.
BACKGROUND AND OBJECTIVES: Intrathecal fentanyl with bupivacaine provides rapid labor analgesia of limited duration. We investigated the effect of initiating an epidural infusion of 0.1% ropivacaine with fentanyl 2 microg/mL and epinephrine 1:400,000 (REF) on the duration of analgesia and incidence of side effects after intrathecal injection in the combined spinal and epidural technique. METHODS: Thirty-four nulliparous parturients with a cervical dilation of 3 to 5 cm were randomized to receive epidural saline or REF at 10 mL following the intrathecal injection of fentanyl 25 microg and bupivacaine 2.5 mg. Degree of analgesia, severity of pruritus, motor block, blood pressure, and sensory level to coolness were assessed until the patient requested additional analgesia. RESULTS: Analgesia was significantly longer in the REF group, 158.4 +/- 59.6 minutes versus 103.8 +/- 26.2 minutes. The decrease in blood pressure compared with the blood pressure at intrathecal injection was greater for the REF group at all times, but achieved statistical significance at 60 minutes. There was no difference in ephedrine use, pruritus, or motor block between groups. There was no difference in sensory level to coolness at 90 minutes after intrathecal injection between groups. CONCLUSIONS: Initiating an infusion of REF prolongs the duration of analgesia, but also results in a greater decrease in blood pressure. Despite this effect on blood pressure, there was no difference in ephedrine use.
Adjuvants, Anesthesia↗
Maternal hypothermia: implications for obstetric nurses.
Hypothermia, a core body temperature of less than 95 degrees F (35 degrees C), is a common intraoperative complication among adult patients and may occur in obstetric patients. Obstetric patients are predisposed to hypothermia because of vasodilation from pregnancy, administration of anesthetics and pharmacologic agents, and inherent blood loss with rapid fluid replacement during delivery. Morbidity associated with hypothermia occurs from complications such as hypotension, cardiac arrhythmias, increased oxygen consumption or respiratory depression, and disseminated intravascular coagulation. Interventions include preventive measures such as maintaining reasonable ambient room temperatures, avoiding infusion of cold solutions, and promptly assessing postoperative temperature, as well as corrective measures--rewarming the patient, placing the patient on dry surfaces, minimizing additional heat loss, and providing external heat sources.
Body Temperature Regulation↗