Fentanyl for epidural intravascular test dose in obstetrics.

BACKGROUND AND OBJECTIVES: Although dizziness and drowsiness may be produced with either intravenous or epidural fentanyl, their occurrence after an intravenous injection is more rapid and relatively more pronounced. The purpose of this study was to determine whether or not the difference between routes of administration would be a reliable method of detecting an accidental intravascular injection. METHODS: In part 1, using a double-blinded protocol, we prospectively assessed in laboring women the incidence of dizziness, drowsiness, or both associated with intravenous fentanyl (100 micrograms). In random order, subjects received two peripheral intravenous injections: 2 ml of fentanyl and 2 ml of saline, separated by a 3-minute observation period. RESULTS: In group 1 (18/18) and group 2 (22/22), all subjects reported a response to intravenous fentanyl within the one-minute assessment. In part 2, we evaluated in laboring patients the frequency of dizziness, drowsiness, or both to epidural fentanyl (100 micrograms). The study design was identical to part 1; however, the subjects received 2 ml of fentanyl and 2 ml of saline via a functional epidural catheter. In group 3 (1/18) and group 4 (1/22), one subject reported a response to epidural fentanyl within the 3-minute observation period. CONCLUSIONS: Overall, the responses to intravenous fentanyl (40/40) occurred in a remarkably more consistent fashion when compared to epidural fentanyl (2/40). Thus, the results suggest that in laboring patients, intravenous fentanyl produces predictable and easily detectable changes that may be useful in identifying an epidural catheter unintentionally placed intravascularly.

Does the administration of oral Bicitra before elective cesarean section affect the incidence of nausea and vomiting in the parturient?

Soluble oral antacids are commonly used before anesthesia for cesarean section. The purpose of this prospective, single institution, randomized experimental study was to examine the relationship of oral administration of Bicitra (sodium citrate and citric acid) to the incidence of nausea and vomiting in patients undergoing elective cesarean section utilizing regional anesthesia, and to evaluate its effectiveness in neutralizing gastric acid. Eighty-six patients were studied (39 in a control group and 47 in a Bicitra treatment group) to ascertain if there was any difference with regard to height, weight, parity, gravity, age, race, incidence of heartburn with pregnancy, incidence of nausea with pregnancy, length of NPO status, preoperative systolic blood pressure (SBP), perioperative low level of SBP, and cumulative drop in SBP. Pearson chi square analysis showed no significant difference between the two groups for all variables or the incidence of nausea and vomiting. No significant difference was noted in the mean pH and volume of emesis of seven subjects analyzed using pooled t tests. After initial hypothesis testing was concluded, the sample was divided into two groups, those who experienced nausea and those who were free from nausea. The nausea group demonstrated a significantly greater cumulative decrease in SBP than did the non-nausea group. Larger patients (mean cube root weight index of 2.78) tended to become nauseated more frequently.

Transdermal scopolamine decreases nausea and vomiting following cesarean section in patients receiving epidural morphine.

The authors evaluated the antiemetic properties of transdermal scopolamine (TDS) in healthy patients undergoing elective cesarean section and receiving epidural morphine for postoperative analgesia. Prior to administration of anesthesia, 203 patients had either TDS or a placebo study patch applied behind one ear. All patients were hydrated with lactated Ringer's solution iv and given 2.0% lidocaine with 1:200,000 epinephrine epidurally for surgical anesthesia. Following delivery of the infant, 4 mg of morphine sulphate was injected through the epidural catheter. After the operation patients were evaluated by "blinded" observers at 2, 4, 6, 8, 10, 24, and 48 h for nausea, vomiting, retching, pain relief, itching, and adverse effects. In addition, medications received were noted. No differences were found between the groups in terms of severity or incidence of pain, or requests for analgesic or antipruritic medication. Although there was no difference between the groups in the first 2 h, patients with TDS had significantly less nausea, vomiting, and retching than patients in the placebo group in each time interval between 2 and 10 h. Additionally, the TDS group required less antiemetic medication. There was no difference in the frequency of retching or vomiting between groups. Side effects were minimal and equal in both groups. The authors conclude that TDS results in a decreased incidence of nausea and vomiting in patients who have delivered by cesarean section and received epidural morphine. TDS appears safe for continuous antiemetic administration.

Unrecognized thrombocytopenia and regional anesthesia in parturients: a retrospective review.

Charts from 2929 consecutive parturients were reviewed. Twenty-four had platelet counts less than 100,000/microL in the peripartum period. Seventeen of the 24 had predisposing causes for thrombocytopenia, including preeclampsia (nine), immune thrombocytopenia purpura (two), infection (three), placenta accreta (one), abruption (one), and excessive surgical bleeding (one). Seven had asymptomatic thrombocytopenia of unknown origin. Fourteen of the 24 thrombocytopenic patients received regional anesthesia, and none had permanent sequelae. Based upon this retrospective review, peripartal thrombocytopenia (15,000-99,000/microL) did not increase the risk of neurologic complications after a regional anesthetic. There have been no reports in the literature of spinal or epidural hematomas in parturients after regional anesthesia, except for one patient with a spinal ependymoma.

Anaesthesia for caesarean delivery in a patient with May-Hegglin anomaly.

The anaesthetic management for Caesarean delivery is described in a patient with May-Hegglin anomaly. The condition, which is inherited as an autosomal dominant characteristic, has features of thrombocytopenia and a bleeding diathesis. Labour was induced and she received type specific platelet transfusion. Spinal anaesthesia, using five per cent lidocaine, 75 mg, with epinephrine and 0.5 mg morphine sulphate produced satisfactory operating conditions, excellent postoperative analgesia, and uncomplicated initial recovery.

The effects of naloxone associated with the intrathecal use of morphine in labor.

The efficacy of naloxone in reducing the incidence of side effects after intrathecal injection of morphine and the effects of maternal naloxone administration on the condition of the newborn were evaluated in 40 patients. Patients in labor were given a 1-mg intrathecal injection of morphine and, 1 hr later, either a 0.4-mg bolus of naloxone, followed by a 0.4-0.6 mg/hr intravenous infusion of naloxone, or an intravenous bolus of saline, followed by an intravenous infusion of saline. Intrathecal morphine provided at least 50% pain relief in 78% of patients given naloxone, and in 82% given saline. Intravenous naloxone significantly decreased the incidence of pruritus during labor and delivery. There was no significant decrease in the incidence of nausea, vomiting, somnolence, dizziness, or urinary retention in patients given naloxone. Despite placental transfer of naloxone, neonatal outcome was not adversely affected. For both groups, maternal beta-endorphin levels decreased significantly with the onset of analgesia and returned to control levels at delivery. We conclude that intravenous infusion of naloxone reduced pruritus after intrathecal injection of 1 mg of morphine for labor pain without lessening analgesia or adversely affecting maternal or neonatal status.

Effect of intrathecal morphine during labor on maternal plasma beta-endorphin levels.

Plasma beta-endorphin was measured in 16 patients in labor prior to and after complete onset of analgesia with 1 mg of morphine administered intrathecally. Human beta-endorphin levels were determined by radioimmunoassay following silicic acid extraction of plasma samples and separation of the beta-endorphin fraction by gel chromatography. Plasma beta-endorphin levels decreased significantly (p less than 0.005) after intrathecal morphine from 76 +/- 9.7 to 46.3 +/- 9.1 fmol/ml (mean +/- SE), possibly because of decreased pituitary beta-endorphin secretion in response to alleviation of labor pain.

Epidural morphine analgesia after cesarean delivery.

The effectiveness and safety of 5 mg of epidurally administered morphine for postoperative analgesia was determined in 276 healthy women undergoing cesarean delivery. Overall pain relief, time to administration of additional analgesic medications, and adverse side effects were evaluated. Epidural injection of 5 mg of morphine provided good to excellent pain relief lasting 24 to 36 hours for 83% of patients. Also, review of hospital records for a subset of 34 patients revealed that requirements for additional systemic analgesics were markedly less when postoperative pain relief was provided by epidural administration of morphine than by conventional analgesia therapy. Pruritus, nausea, and vomiting occurred frequently, but were easily treated. Although late respiratory depression did not occur in this group, the authors continue to observe patients closely and monitor respiratory rates for 24 hours.

Bupivacaine-induced cardiac arrhythmias in sheep.

Controversy persists about the cardiac toxicity of bupivacaine if accidentally administered intravenously during regional anesthesia. Using awake, unanesthetized sheep, we evaluated the cardiac effects of low and high equivalent doses of lidocaine and bupivacaine given intravenously over 10 s. All animals convulsed within 30 s of injections. Although both drugs significantly increased heart rate and systemic and pulmonary arterial blood pressure for up to 10 min, cardiac output was affected variably. The magnitude of hemodynamic changes that each drug produced did not differ significantly from each other at either dose level. However, of the sheep receiving intravenous lidocaine, none developed arrhythmias other than mild sinus tachycardia and minimal ST-T wave changes (which occurred in 25% of the animals). After intravenous bupivacaine injection, all sheep had transient changes on the EKG and/or arrhythmias (e.g., supraventricular tachycardia; atrioventricular condition blocks; ventricular tachycardia; multiform premature ventricular contractions; wide QRS complexes; ST-T wave changes; and in one animal, fatal ventricular fibrillation). Normal sinus rhythm usually returned within 8-10 min. Arterial blood gas and acid-base values stayed within the normal range during the studies, and serum potassium did not change significantly from control. In conclusion, in conscious adult sheep, equivalent doses of lidocaine or bupivacaine produced similar central nervous system (CNS) toxicity when rapidly injected intravenously. In the absence of marked hypoxia, respiratory or metabolic acidosis, hyperkalemia, or hypotension, serious cardiac arrhythmias occurred after bupivacaine but not lidocaine.