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Biomedical subjects

D M Dewan

Publications and source records attributed to D M Dewan.

At least 19 recordsLinked to original sources
PubMed2000

An evaluation of informed consent prior to epidural analgesia for labor and delivery.

This investigation was performed to determine the ability of a parturient to recall the pre-anesthesia discussion with her anesthesiologist and to determine if written consent added to this discussion improves recall. Eighty-two women presenting in labor were randomized to 'verbal' and 'verbal plus written' consent for epidural labor analgesia and were contacted 5 to 7 months after a pre-anesthetic interview. Ten objective questions were posed at this time that addressed issues that were 'true risks', 'false risks', and 'situational' issues related to the consent process. These responses were scored on a point scale so that a maximal objective recall score of 100 points was possible. Median recall score was 80 (70-90) in the 'verbal' group and 90 (80-100) in the 'verbal plus written' group. This difference was statistically significant (P< 0.01). In addition, three subjective questions were asked of all women at this time. All but six women (one 'verbal plus written' and five 'verbal' group patients) expressed that written consent would help them 'remember and appreciate the different anesthetic options, risks, and procedures'. Four of these same women (one 'verbal plus written' and three 'verbal' group patients) thought a written consent process was 'alarming'. Two of these same women (both 'verbal' group patients) reported that they felt unable to give informed consent.

Clinical Trial↗
PubMed1996

Metoclopramide exaggerates stress-induced tachycardia in pregnant sheep.

Metoclopramide is often administered to hasten gastric emptying prior to cesarean section and during labor, but has also been demonstrated to increase catecholamine release during stress and to increase heart rate and blood pressure in nonpregnant humans. The purpose of this study was to examine the maternal and fetal effects of metoclopramide during maternal stress in pregnant ewes. After baseline measures, eight ewes were randomly allocated to receive either intravenous metoclopramide, 10 mg, or saline, followed in 10 min by nonpainful stress to increase mean arterial pressure 40%-45% for 30 s. At least 2 days later, the ewes received the alternate treatment. Metoclopramide, but not saline, increased resting maternal heart rate. In the 10 min after maternal stress, maternal heart rate was increased more after metoclopramide than after saline treatment, whereas maternal blood pressure, uterine blood flow, and fetal hemodynamic variables and arterial blood gas tensions did not differ between the two treatments. Whereas these results are not consistent with a generalized increase in sympathetic nervous system tone after a single dose of metoclopramide, they do suggest that metoclopramide may exaggerate tachycardia after stress, encountered frequently both during and after cesarean section.

Animals↗
PubMed1994

Previous wet tap does not reduce success rate of labor epidural analgesia.

Whether unintentional dural puncture (wet tap) during a previous labor epidural increases the failure rate of epidural analgesia for later deliveries is controversial. In this study, charts of 47 women with a previous wet tap who received epidural analgesia for labor were compared to those of 500 consecutive women receiving epidural analgesia in 1991 and, separately, to 44 women matched for month of delivery, previous epidural without a wet tap, and the same anesthesiologist. In comparison to the 500 consecutive control patients, women with a previous wet tap had a lower incidence of epidural catheter manipulation for inadequate block (9% vs 20%), but a similar incidence of catheter removal for failed block (4% vs 6.7%). In comparison to matched control patients, women with a previous wet tap had a similar incidence of epidural catheter manipulation and removal for inadequate or failed blocks. Epidural analgesia was considered successful in 93% of cases and 89% of matched control subjects by chart review. Two women (4%) with previous wet tap experienced a second wet tap during attempted epidural catheterization, compared to 0% in 500 consecutive patients (P < 0.001). These data suggest that there is no decrease in the success rate of epidural analgesia in women with a previous wet tap, although the chance for a repeated wet tap may be increased.

Adult↗
PubMed1993

Anesthetic and obstetric outcome in morbidly obese parturients.

BACKGROUND: Large studies reporting anesthetic outcome for morbidly obese parturients are lacking. This study compares the anesthetic and obstetric outcome in morbidly obese parturients and matched control parturients. METHODS: Anesthesia records were prospectively collected for all patients delivering between September 1978 and November 1989 whose weight exceeded 136.4 kg (300 pounds) at the time of delivery. A retrospective control patient group was collected by matching the first patient weighing less than 136.4 kg, delivered in the same month by the same obstertrician, to the corresponding morbidly obese parturient. Anesthetic and obstetric outcome variables were extracted from medical records and analyzed. RESULTS: Sixty-two percent of 117 morbidly obese women underwent cesarean section, while only 24% of control patients delivered abdominally (P < 0.05). Forty-eight percent of all laboring morbidly obese parturients required emergency cesarean section, compared with 9% of control laboring parturients (P < 0.05). Epidural anesthesia was used successfully for labor and cesarean delivery in 74 of 79 morbidly obese women and 66 of 67 control patients. When compared with control patients, initial epidural anesthesia failure was significantly more likely in morbidly obese women, requiring epidural catheter replacement. Difficult tracheal intubation occurred in 6 of 17 morbidly obese women, compared with 0 of 8 control women (P = 0.06). Morbidly obese women had increased incidences of antepartum medical disease, prolonged cesarean section operation times, serious postoperative complications, and increased hospital stays. CONCLUSIONS: The high incidences of antepartum medical disease and emergency cesarean section complicate anesthetic care in the morbidly obese parturients. Epidural anesthesia is feasible; however, the high initial failure rate necessitates early catheter placement, critical block assessment and catheter replacement when indicated, and provision for alternative airway management.

Adult↗
PubMed1993

Obstetric and anesthetic considerations in the May-Hegglin anomaly. A case report.

The obstetric and anesthetic considerations in the management of a patient with the May-Hegglin anomaly, an autosomal dominant platelet deficiency, are discussed. A review of the medical literature notes three previous case reports of May-Hegglin anomaly in pregnancy. In addition to the two successful pregnancies reported in this paper, there are four infant survivors among the five reported pregnancies. Anesthetic managements included general and spinal anesthesia: the latter employed following platelet transfusion. A successful pregnancy should be anticipated when management includes a well-informed patient and coordinated obstetric and anesthetic care.

Adult↗
PubMed1992

The effectiveness of low dose droperidol in controlling nausea and vomiting during epidural anesthesia for cesarean section.

The antiemetic efficacy of 0.5 mg of droperidol was evaluated in 128 term parturients undergoing elective and non-urgent cesarean section with epidural anesthesia. Following delivery, parturients received intravenously either 0.5 mg of droperidol or normal saline in a double-blinded fashion. Droperidol decreased nausea after delivery from 41 to 13% (P=0.001). There was no significant decrease in the incidence of vomiting. Analysis of the data using logistic regression analysis showed that increasing age (P = 0.002), hypotension after delivery (P = 0.040), and vomiting prior to delivery (P = 0.017) were associated with increased nausea after delivery. No extrapyramidal symptoms or significant changes in pulse rate or blood pressure were associated with droperidol administration. We conclude that 0.5 mg of intravenous droperidol decreases nausea in term parturients undergoing non-urgent cesarean section with epidural anesthesia without producing unwanted side-effects.

Journal Article↗
PubMed1991

Maternal and fetal effects of labetalol in pregnant ewes.

Labetalol has been advocated to rapidly decrease blood pressure in preeclamptic women and to blunt the hemodynamic response to tracheal intubation. To assess labetalol's actions in a setting of uterine vasoconstriction, saline or labetalol (1 mg/kg) was infused into maternal venous catheters in 12 pregnant ewes receiving continuous maternal intravenous infusions of norepinephrine. Norepinephrine increased maternal mean arterial pressure (MAP) to 120 +/- 4% of control and decreased uterine blood flow to 45 +/- 6% of control. Labetalol, but not saline, altered these parameters: it decreased MAP to 101 +/- 3% and increased uterine blood flow to 70 +/- 7% of prenorepinephrine values. In the second protocol, to assess the degree of labetalol-induced fetal adrenergic blockade, 7 pregnant ewes received, on separate days, saline or labetalol (0.3, 1.0, 3.0 mg/kg) via a maternal venous catheter. Maternally administered labetalol produced minor (less than 12%) decreases in maternal and fetal MAP, without significantly altering heart rate (HR). At each labetalol dose, the degree of alpha- and beta-adrenergic blockade, determined by phenylephrine and isoproterenol challenge, was greater in the ewe than in the fetus. In the near-term pregnant ewe, intravenous (iv) bolus administration of labetalol ameliorated the effects of increased circulating norepinephrine on maternal MAP, uterine blood flow, and fetal pH and arterial O2 tension (PaO2), and produced less adrenergic blockade in the fetus than in the mother.

Adrenergic alpha-Antagonists↗
PubMed1990

Labor analgesia with epidural bupivacaine plus fentanyl: enhancement with epinephrine and inhibition with 2-chloroprocaine.

Epidural injection of drug combinations may decrease toxicity by decreasing the dose of each component, but may also result in detrimental drug interactions. In this study interactions among bupivaciane, fentanyl, epinephrine, 2-chloroprocaine, and lidocaine for epidural analgesia during labor were examined. In part 1 of the study, healthy parturients received in a random manner either 10 ml of 0.25% bupivacaine with 5 micrograms/ml fentanyl (n = 50), or 10 ml of this combination with 3.33 micrograms/ml freshly added epinephrine (n = 50). Epinephrine prolonged the median duration of pain relief (180 vs. 138 min, P less than 0.05) without affecting duration of first or second stages of labor, or neonatal Apgar scores. Blood pressure decreased slightly more in those receiving epinephrine, although the incidence of hypotension requiring treatment did not differ between groups. Part 2 of the study evaluated the possibility that local anesthetic used for confirming catheter tip location may interfere with the analgesic action of this bupivacaine-fentanyl-epinephrine (BFE) combination. In 50 additional parturients, a test dose of either 2-chloroprocaine (n = 25) or lidocaine (n = 25) was injected through the epidural catheter and was followed by injection of the BFE mixture. The lidocaine test dose group had a greater duration of analgesia than the 2-chloroprocaine test dose group (median duration of 164 vs. 91 min, P less than 0.05). The authors conclude that the addition of epinephrine 3.33 micrograms/ml significantly increases the duration of analgesia obtained from 0.25% bupivacaine with 5 micrograms/ml fentanyl. However, prior injection of 2-chloroprocaine, but not lidocaine, significantly decreases the duration of analgesia achieved with this BFE mixture.

Analgesia, Epidural↗
PubMed1990

Intrathecal clonidine in obstetrics: sheep studies.

Clonidine may be administered intrathecally as an adjunct to local anesthetics or accidentally during attempted epidural analgesia. To examine clonidine's acute maternal and fetal effects, the authors injected clonidine (100, 300, 750, 1500 micrograms cumulative dose at 15-min intervals) intrathecally in nine chronically prepared near-term ewes. Unlike intrathecal saline injection, which did not alter any parameters, clonidine altered maternal blood pressure in a biphasic manner (depression at lower doses and return to baseline after the highest dose). Clonidine produced a dose-dependent decrease in maternal and fetal heart rate. After the highest dose, 1500 micrograms, PO2 decreased in both ewe and fetus, accompanied by fetal hypertension and bradycardia. Clonidine increased maternal and fetal serum glucose, but not cortisol. Although clonidine-induced hypoxemia and hyperglycemia occur only in sheep, fetal bradycardia may limit the usefulness of clonidine in large doses (greater than 10 micrograms/kg) in obstetrics. Lower doses, such as may be used to enhance spinal anesthesia, are well tolerated in sheep.

Adrenergic alpha-Antagonists↗
PubMed1989

Intravenous clonidine hydrochloride toxicity in pregnant ewes.

Administration of intravenous clonidine hydrochloride has been advocated to rapidly control blood pressure in severe preeclampsia. To examine clonidine's acute maternal and fetal effects were intravenously injected 300 micrograms clonidine in eight chronically prepared normotensive near term ewes. Unlike intravenous saline solution injection, clonidine produced significant toxicity--intraamniotic pressure increased 97 +/- 27% (p less than 0.05), uterine blood flow decreased 55 +/- 7% (p less than 0.001), maternal and fetal serum glucose increased 158 +/- 23% and 249 +/- 91%, respectively (p less than 0.001), and maternal and fetal Po2 decreased to 44 mm Hg +/- 4 mm Hg and 13 mm Hg +/- 1 mm Hg, respectively (p less than 0.05). Maternal and fetal blood pressure and serum cortisol were unaffected by clonidine, whereas heart rate decreased. No adverse maternal or fetal effects were noted with serum clonidine concentrations less than 1.0 ng/ml. Direct fetal infusion of clonidine did not lower fetal arterial Po2 levels, although heart rates decreased and serum glucose levels increased. The multiple effects of clonidine infusion are best explained by actions on alpha 2-adrenergic receptors. These results suggest that intravenous administration of clonidine may adversely affect the fetus by direct actions and by alterations in maternal physiology.

Animals↗
PubMed1989

Epidural clonidine analgesia in obstetrics: sheep studies.

Epidural clonidine administration produces analgesia by a nonopiate, spinal mechanism, and offers advantages over other epidural agents for labor analgesia. To examine clonidine's acute maternal and fetal effects, the authors injected clonidine, 300 micrograms, epidurally in seven chronically prepared, near term ewes. Unlike epidural saline injection, clonidine increased maternal and fetal serum glucose (by 178 +/- 30% and 190 +/- 30%, respectively; mean +/- SEM, P less than .01) 1 h following injection. Maternal and fetal serum cortisol and arterial blood gas tensions were unchanged following clonidine. Epidural clonidine injection produced minor decreases (10-15%) in heart rate in ewe and fetus, without altering maternal and fetal blood pressure, intra-uterine pressure, or uterine blood flow. Maternal and fetal serum clonidine concentrations peaked at 58 +/- 8 and 73 +/- 5 min following injection, respectively, and declined with similar half-lives. Heart rate correlated negatively with serum clonidine concentration in both ewe and fetus (P less than .05). Apart from hyperglycemia, which does not occur in humans, these results in sheep suggest that epidurally administered clonidine does not adversely affect the fetus and may be evaluated as an analgesic in obstetrics.

Analgesia, Epidural↗
PubMed1989

Anesthetic management for obstetric hysterectomy: a multi-institutional study.

A prospectively designed review of all obstetric hysterectomies performed in five university hospitals between November 1, 1984 and October 31, 1987 has been performed. There were 41,107 deliveries and 46 obstetric hysterectomies, an incidence of 0.11%. Twenty-five hysterectomies were elective and 21 were emergent. The indication for 11 of the 21 emergency hysterectomies was placenta previa and/or accreta. Women in the emergency group had greater intraoperative blood loss, were more likely to have intraoperative hypotension, and were more likely to receive donor blood than women in the elective group (P less than 0.05). Twelve patients (eight from the elective group and four from the emergency group) received continuous epidural anesthesia, and none required intraoperative induction of general anesthesia. There was no evidence that epidural anesthesia significantly affected blood loss, crystalloid replacement, or requirement for transfusion in the elective group. Abnormal placentation now represents a major indication for emergency obstetric hysterectomy. Furthermore, significant hemorrhage is more likely with emergency obstetric hysterectomy than with elective hysterectomy. Finally, elective cesarean hysterectomy is not a contraindication to performance of continuous epidural anesthesia.

Adult↗
PubMed1987

Effect of gravity on the spread of extradural anaesthesia for caesarean section.

The effect of gravity on the spread of extradural anaesthesia was evaluated in a series of parturients undergoing elective Caesarean section. Following placement of an extradural catheter, 25 patients were placed 30-40 degrees head-up for 20 min during the administration of the local anaesthetic drug; 25 additional patients remained supine during injection. Extradural anaesthesia was induced with 3% 2-chloroprocaine 23 ml and analgesia to pinprick assessed at 5-min intervals. Additional drug was given after 20 min, if required. There were no differences in the rate of onset of sacral blockade or in the extent of neural blockade between the two groups. The semi-upright position was not necessary to ensure adequate sacral anaesthesia for Caesarean section.

Adult↗
PubMed1987

Epidural clonidine produces antinociception, but not hypotension, in sheep.

Intrathecally administered clonidine produces analgesia, but also produces hypotension. To assess the effects of epidural administration, the authors inserted lumbar epidural catheters in seven nonpregnant ewes, and injected, on separate days, clonidine (50-750 mcg), morphine (5-10 mg), and a clonidine-morphine combination (clonidine 150 mcg + morphine 5 mg). Clonidine produced dose-dependent antinociception and sedation, with the lowest maximally effective antinociceptive dose being 300 mcg. Morphine produced less intense antinociception than clonidine, and did not potentiate clonidine's effect. Antinociception, but not sedation, following clonidine injection was reversed by epidural injection of the alpha 2-adrenergic antagonist, idazoxan. Epidurally administered naloxone and prazosin did not reverse clonidine's antinociceptive effect, nor did intravenously administered idazoxan. Epidurally administered clonidine did not decrease blood pressure or heart rate or affect arterial blood gas tensions or spinal cord histology. These data suggest that epidurally administered clonidine produces analgesia by a local, alpha 2-adrenergic mechanism. In sheep, epidurally administered clonidine does not produce hypotension.

Analgesia↗