John J. Angel

Comparison of Ondansetron Versus Placebo to Prevent Postoperative Nausea and Vomiting in Women Undergoing Ambulatory Gynecologic Surgery

BackgroundPostoperative nausea and emesis, especially in ambulatory surgical patients, remains a troublesome problem. This study was performed to compare the incidence of nausea and emesis during the 24-h postoperative period in ondan-setron-treated patients versus placebo-treated patients. MethodsUsing a randomized prospective double-blind study design, women between the ages of 18 and 70 yr undergoing gynecologic surgical procedures with general opioid anesthesia on an outpatient basis were enrolled. Ondansetron or placebo was administered prior to induction of anesthesia. Patients were stratified according to history of nausea and emesis during previous exposure to general anesthesia and randomized to dose received. ResultsData from the 544 women showed that all doses of intravenous ondansetron tested (1, 4, and 8 mg) were significantly more effective (62%, 76%, and 77%, respectively) than placebo (46%) in reducing the incidence of emesis following surgery until 24 h after recovery room entry. All these doses were more effective than placebo in patients with no prior history of emesis following surgery and the 4− and 8-mg doses were more effective than placebo in patients with a prior history of emesis following surgery. All doses of ondansetron tested were generally well tolerated with adverse events, clinical laboratory tests, and recovery room vital signs similar to those of placebo. Serum aspartate transaminase (AST) was increased in five patients (1 mg, 2 patients; 4 mg, 1 patient; 8 mg, 2 patients). In the three patients in whom subsequent analysis were performed, the serum AST had decreased to preoperative levels. ConclusionsOndansetron given intravenously to prevent postoperative nausea and emesis was highly effective in the 4− and 8-mg doses in women having ambulatory gynecologic surgery.

Remifentanil Compared with Alfentanil for Ambulatory Surgery Using Total Intravenous Anesthesia

The purpose of this study was to test the hypothesis that using a 1:4 ratio of remifentanil to alfentanil, a remifentanil infusion would provide better suppression of intraoperative responses and comparable recovery profiles after ambulatory laparoscopic surgery than an alfentanil infusion, as part of total intravenous anesthesia. Two hundred ASA physical status I, II, or III adult patients participated in this multicenter, double-blind, parallel group study. Patients were randomly assigned 2:1 to either the remifentanil-propofol or alfentanil-propofol regimens. The anesthesia sequence was propofol (2 mg/kg intravenously [IV] followed by 150 micro g [centered dot] kg (-1) [centered dot] min-1), and either remifentanil (1 micro g/kg IV followed by 0.5 micro g [centered dot] kg-1 [centered dot] min-1) or alfentanil (20 micro g/kg IV followed by 2 micro g [centered dot] kg-1 [centered dot] min (-1)), and vecuronium. After trocar insertion, infusion rates were decreased (propofol to 75 micro g [centered dot] kg-1 [centered dot] min-1; remifentanil to 0.25 micro g [centered dot] kg-1 [centered dot] min-1; alfentanil to 1 micro g [centered dot] kg-1 [centered dot] min-1). Alfentanil and propofol were discontinued at 10 and 5 min, respectively, before the anticipated end of surgery (last surgical suture); remifentanil was discontinued at the end of surgery. Recovery times were calculated from the end of surgery. The median duration of surgery was similar between groups (39 min for remifentanil versus 34 min for alfentanil). A smaller proportion of remifentanil patients than alfentanil patients had any intraoperative responses (53% vs 71%, P = 0.029), had responses to trocar insertion (11% vs 32%, P < 0.001), or required dosage adjustments during maintenance (24% vs 41%, P < 0.05). Early awakening times were similar. Remifentanil patients qualified for Phase 1 discharge later and were given postoperative analgesics sooner than alfentanil patients (P < 0.05). Actual discharge times from the ambulatory center were similar between groups (174 min for remifentanil versus 204 min for alfentanil) (P = 0.06). In conclusion, remifentanil can be used for maintenance of anesthesia in a 1:4 ratio compared with alfentanil, for total IV anesthesia in ambulatory surgery. This dose of remifentanil provides more effective suppression of intraoperative responses and does not result in prolonged awakening. (Anesth Analg 1997;84:515-21)

Efficacy of repeat intravenous dosing of ondansetron in controlling postoperative nausea and vomiting: a randomized, double-blind, placebo-controlled multicenter trial

STUDY OBJECTIVES To compare repeat intravenous (i.v.) dosing of ondansetron 4 mg with placebo for the treatment of postoperative nausea and vomiting (PONV) in patients for whom prophylactic, preoperative ondansetron 4 mg i.v. was inadequate DESIGN Randomized, double-blind, placebo-controlled study. SETTING Ten outpatient surgical centers in the United States. PATIENTS 2,199 male and female ASA physical status I, II, and III patients > or = 12 years old scheduled to undergo outpatient surgical procedures and receive nitrous oxide-based general anesthesia. INTERVENTIONS Ondansetron 4 mg i.v. was administered to all patients before induction of general anesthesia. Patients who experienced PONV or requested antiemetic therapy within 2 hours after discontinuation of inhaled anesthesia were randomized (1:1) to either a repeat i.v. ondansetron 4 mg dose or placebo. MEASUREMENTS AND MAIN RESULTS Of the 2,199 patients prophylactically treated with ondansetron 4 mg before anesthesia induction, 1,771 (80.5%) did not experience PONV or request antiemetic therapy during the 2 hours following discontinuation of anesthesia. Of the 428 patients who experienced PONV or requested antiemetic therapy during the same period, and were randomized to additional treatment (214 randomized to ondansetron, 214 randomized to placebo), the incidence of complete response (no emesis, no rescue medication, no study withdrawal) was similar for both ondansetron-randomized and placebo-randomized groups for the 2-hour (34% and 43%, respectively, p = 0.074) and 24-hour (28% and 32%, respectively, p = 0.342) postrandomization study periods. Repeat ondansetron dosing was not more effective than placebo in controlling either postoperative emesis or the severity/duration of postoperative nausea. The administration of an additional dose of ondansetron 4 mg postoperatively did not result in an increased incidence of adverse effects. CONCLUSIONS In patients for whom preoperative prophylaxis with ondansetron 4 mg i.v. is not successful, a repeat dose of ondansetron 4 mg i.v. in the postanesthesia care unit does not appear to offer additional control of PONV.

Side effects and complications of cervical epidural steroid injections

Two hundred and four cervical epidural injections of corticosteroids were performed on 142 patients for the treatment of cervical pain over a 1-yr period. Injections were performed at the C7-T1 interspace with 10-15 mL of 0.5% lidocaine containing 1 mg per kg of methylprednisone acetate. Four complications occurred: two dural punctures without sequelae; one episode of upper extremity weakness, which resolved in 24 hr; and one episode of nausea and vomiting lasting 12 hr. In addition, two side effects were frequently reported: stiff neck lasting 12-24 hr occurred in 13.2% of patients, and a mild facial flushing with subjective (but not objective) fever lasting about 12 hr occurred in 9.3% of patients. In this large series, the procedure appears safe to use in an outpatient setting.

Long-term results of cervical epidural steroid injections

Fifty-eight patients undergoing cervical epidural injections of corticosteroids were followed for a 6-month period. Patients with 90% pain relief lasting 6 month were considered to have excellent results, those with >50% pain relief lasting at least 6 weeks were considered to have poor results. Six months after the injection, 41.4% of patients had excellent pain relief by our criteria. Twenty-nine percent of patients reported good results and 29.3% had poor results. Those patients with the diagnosis of cervical spondylosis and those with subacute cervical strain had statistically significantly (p <0.001, difference of proportions test) better results than patients with other diagnosis. The procedure of cervical epidural steroid injection may be most effective in patients with cervical degenerative joint diseases as the etiology of their cervical pain.

Neuromuscular transmission studies in preeclamptic women receiving magnesium sulfate

The purpose of the study was to evaluate the neuromuscular transmission defect in preeclamptic women receiving intravenous magnesium sulfate and to study the correlation of the degree of defect with serum magnesium and calcium levels. The study population included: group 1, 14 preeclamptic women receiving magnesium sulfate and undergoing induction of labor; group 2, six preeclamptic women studied in the postpartum period while receiving magnesium sulfate; and group 3, 10 normotensive women undergoing induction of labor. The neuromuscular transmission studies were performed with standard techniques before and during the administration of magnesium sulfate. During magnesium sulfate therapy patients in groups 1 and 2 showed abnormal responses characterized by an initial low-amplitude muscle action potential followed by a progressive increase in the amplitudes of the successive responses. There was significant correlation between the degree of the neuromuscular transmission defect and serum magnesium levels, serum calcium levels, and the magnesium/calcium ratio in groups 1 and 2. All studies were normal in group 3. The findings confirm the occurrence of abnormal neuromuscular transmission in preeclamptic women receiving magnesium sulfate, and the intensity of the defect correlates significantly with increased serum magnesium levels and decreased serum calcium levels.

Ocular Microtremor During General Anesthesia: Results of a Multicenter Trial Using Automated Signal Analysis

Ocular microtremor (OMT) is a fine physiologic tremor of the eye related to neuronal activity in the reticular formation of the brainstem. The frequency of OMT is suppressed by propofol and sevoflurane and predicts the response to command at emergence from anesthesia. Previous studies have relied on post hoc computer analysis of OMT wave forms or on real-time measurements confirmed visually on an oscilloscope. Our overall aim was to evaluate an automated system of OMT signal analysis in a diverse patient population undergoing general anesthesia. In a multicenter trial involving four centers in three countries, we examined the accuracy of OMT to identify the unconscious state and to predict movement in response to airway instrumentation and surgical stimulation. We also tested the effects of neuromuscular blockade and patient position on OMT. We measured OMT continuously by using the closed-eye piezoelectric technique in 214 patients undergoing extracranial surgery with general anesthesia using a variety of anesthetics. OMT decreased at induction in all patients, increased transiently in response to surgical incision or airway instrumentation, and increased at emergence. The frequency of OMT predicted movement in response to laryngeal mask airway insertion and response to command at emergence. Neuromuscular blockade did not affect the frequency of OMT but decreased its amplitude. OMT frequency was unaffected by changes in patient position. We conclude that OMT, measured by an automated signal analysis module, accurately determines the anesthetic state in surgical patients, even during profound neuromuscular blockade and after changes in patient position.

Changes in maternal middle cerebral artery blood flow velocity associated with general anesthesia in severe preeclampsia.

UNLABELLED In women with severe preeclampsia, significant increases in mean arterial pressures (MAP) are common after rapid induction of general anesthesia (GA) and tracheal intubation. The objectives of this prospective study were to assess the effects of the rapid induction-intubation technique on middle cerebral artery (MCA) flow velocity in severe preeclampsia and to examine the correlation between mean MCA flow velocity (Vm) and MAP. Eight women with severe preeclampsia (study group) and six normotensive women at term (control group) scheduled to undergo cesarean section under GA were studied. Before induction, patients in the study group received i.v. labetalol in divided doses to lower diastolic pressures to <100 mm Hg. Anesthesia was induced with pentothal 4-5 mg/kg, followed by succinylcholine 1.5 mg/kg to facilitate tracheal intubation. A transcranial Doppler was used to measure Vm. Both Vm and MAP were recorded before induction and every minute for 6 min after intubation. In the study group, after the administration of labetalol, MAP decreased from 129 +/- 9 to 113 +/- 9 mm Hg (P < 0.05), and Vm decreased from 59 +/- 11 to 54 +/- 10 cm/s (P < 0.05). After intubation, MAP increased from 113 +/- 9 to 134 +/- 5 mm Hg (P < 0.001), and Vm increased from 54 +/- 10 to 70 +/- 10 cm/s (P < 0.001). In the control group, while MAP increased significantly from 89 +/- 6 to 96 +/- 4 mm Hg (P < 0.05) after intubation, the concurrent increase in Vm from 49 +/- 5 to 54 +/- 7 cm/s was not significant. There was a significant positive pooled correlation between Vm and MAP (r = 0.5, P < 0.0006) in the study group but not in the control group (r = 0.24). After induction and intubation, both Vm and MAP values were significantly increased in the study group patients at all observation points compared with the control group patients. The findings indicate that Vm increases significantly after rapid-sequence induction of GA and tracheal intubation in women with severe preeclampsia, and there seems to be a direct relationship between MAP and Vm. IMPLICATIONS In women with severe preeclampsia, rapid-sequence induction of general anesthesia and tracheal intubation can cause severe hypertension. Our results indicate that the increase in blood pressure is associated with a significant increase in maternal cerebral blood flow velocity and that there is a significant correlation between these two variables.

Changes in Oxygen Consumption at Weaning After Thoracotomy and After Respiratory Failure

Oxygen (O2) consumption at the time of weaning was studied in 8 patients 24 hours after thoracotomy, 5 with median sternotomy and 3 with left posterolateral incisions, and in 10 patients recovering from respiratory failure.In the thoracotomy group, the change in O2 consumption was significantly increased on assuming spontaneous ventilation. In the recovering respiratory-failure patients, the change in O2 consumption was significantly decreased on assuming spontaneous ventilation; minute ventilation changes in this group varied.

NEUROMUSCULAR TRANSMISSION STUDIES IN PREECLAMPTIC WOMEN RECEIVING MAGNESIUM SULFATE

The purpose of the study was to evaluate the neuromuscular transmission defect in preeclamptic women receiving intravenous magnesium sulfate and to study the correlation of the degree of defect with serum magnesium and calcium levels. The study population included: group 1, 14 preeclamptic women receiving magnesium sulfate and undergoing induction of labor; group 2, six preeclamptic women studied in the postpartum period while receiving magnesium sulfate; and group 3, 10 normotensive women undergoing induction of labor. The neuromuscular transmission studies were performed with standard techniques before and during the administration of magnesium sulfate. During magnesium sulfate therapy patients in groups 1 and 2 showed abnormal responses characterized by an initial low-amplitude muscle action potential followed by a progressive increase in the amplitudes of the successive responses. There was significant correlation between the degree of the neuromuscular transmission defect and serum magnesium levels, serum calcium levels, and the magnesium/calcium ratio in groups 1 and 2. All studies were normal in group 3. The findings confirm the occurrence of abnormal neuromuscular transmission in preeclamptic women receiving magnesium sulfate, and the intensity of the defect correlates significantly with increased serum magnesium levels and decreased serum calcium levels.