Sujit K. Pandit

Further studies of the anti-recall effect of lorazepam: A dose--time--effect relationship.

The time of onset and duration of tlie anti recall action of Iorazcpam were assessed under clinical conditions by measuring recall and rccognition of visual stimuli 24 hours after intravenous administration of Iorazepam. The visual stimuli were first presented 5–240 minutes after 2 mg and 5–360 minutes after 4 mg Iorazepam. Retrograde amnesia was not produced. Lorazepam, 2 mg produced a short anti-recall effect (enterograde amnesia) in 50 per cent of the cases with a latency of 30 minutes and a duration of less than half an hour. Duration and frequency of the anti-recall effect were greater after 4 mg while the latency was shorter. More than 70 per cent of the individuals tested were amnesia for the visual stimuli 15 minutes to 4 hours after 4 mg lorazepam. Sedation was satisfactory and long-lasting following both doses of lorazepam, but was not related to the antirecall effect.

Desflurane Versus Propofol Anesthesia: A Comparative Analysis in Outpatients

This study compares the induction, hemodynamic, and recovery characteristics of a general anesthetic with desflurane to one with propofol. Sixty outpatients presenting for orthopedic surgery received either a propofol induction of anesthesia followed by desflurane and nitrous oxide (Group 1), a propofol induction followed by propofol infusion and nitrous oxide (Group 2), a desflurane and nitrous oxide induction and maintenance (Group 3), or a desflurane induction and maintenance (Group 4). The quality of induction was inferior in Groups 3 and 4 with more breath-holding and excitation than in Groups 1 and 2. However, there was a more rapid emergence in Group 4 patients than any of the other groups. Group 4 patients were able to say their names (5.6 +/- 2.0 min vs 10.3 +/- 3.3 min, 8.6 +/- 3.1 min, and 9.3 +/- 1.5 min for Groups 1, 2, and 3, respectively) sooner after the discontinuation of anesthesia. Nonetheless, intermediate recovery was similar in Groups 2 and 4 being numerically but not statistically more rapid than in Groups 1 and 3. This pattern of intermediate recovery was also demonstrated by psychomotor function test results. Although there was no difference between the groups in postoperative narcotic requirement, more patients in Group 3 vomited (50%) than in either Group 2 (0%) or Group 4 (12.5%). Hemodynamically, the anesthetics were very similar. Although desflurane was a difficult drug to use for induction of anesthesia, this study demonstrates that desflurane is a suitable maintenance anesthetic for ambulatory surgery because it provides a rapid awakening and an intermediate recovery similar to propofol.

Dose-response study of droperidol and metoclopramide as antiemetics for outpatient anesthesia

During the past decade the demand for outpatient surgery has grown rapidly. To keep pace with the changing surgical environment, anesthesiologists have been modifying their anesthetic techniques to ensure a more rapid and a smoother recovery. However, postoperative nausea and vomiting remain the most common anesthesia-related side effects in outpatient surgical facilities (1,2). The incidence of postoperative nausea and vomiting in female outpatients undergoing laparoscopy has been reported to be as high as 50-60% (3). The incidences after strabismus surgery (4) and after therapeutic abortions (5) are also high. A prophylactic antiemetic would be of great value in outpatient surgery and anesthesia. A large number of papers have been published suggesting the use of droperidol, a butyrophenone derivative, as a prophylactic antiemetic agent. Although the majority of the authors found droperidol to be an effective antiemetic, the recommended doses vary widely (4,643). However, side effects, especially somnolence, have been reported with larger doses (4,9). Metoclopramide, a dopaminergic receptor blocker devoid of sedative effects, has also been advocated as an antiemetic, but conflicting results have been reported regarding its efficacy (5,lO-14). A recent paper by Rao, et al. (15) reported no nausea or

Time course of antirecall effect of diazepam and lorazepam following oral administration.

&NA; The time course of antirecall effect and grades of sedation after the oral administration of diazepam and lorazepam were determined in 120 patients. Three standard doses of each drug were employed. Grades of sedation following oral diazepam were dose related, with a latency of 30‐60 min and duration of 120‐150 min. All three doses of lorazepam produced significantly more sedation with a similar latency (30‐60 min) but longer duration (more than 240 min). Peak frequencies of the antirecall effects of diazepam 10, 15, and 20 mg were 5, 20, and 30 per cent, respectively. The duration was about two hours. Peak frequencies of the antirecall effect after lorazepam 2, 3, and 4 mg were 30, 45, and 72 per cent, respectively. Latency of peak action was about 60‐90 min for all the doses, but the duration, especially with 3 and 4 mg doses, was long (4 h).

Toast and tea before elective surgery? A national survey on current practice.

A more tolerant approach to preoperative fasting guidelines for healthy adults undergoing elective surgery was recently recommended by a task force appointed by the American Society of Anesthesiologists. This recommendation liberalizes the intake of clear liquids and specifically allows a light breakfast (e.g., toast and tea or coffee) up to 6 h before elective surgery. We conducted a national survey to determine whether anesthesiologists giving anesthesia in an outpatient setting in the United States were currently following these recommendations, and whether institutional policy reflects these new guidelines. The population consisted of the entire active membership of the Society for Ambulatory Anesthesia, providing an initial sample size of 623 subjects. Most conservatively calculated, we had a response rate of 59.6%. A total of 62% of the respondents said they have an institutional policy in place to allow clear liquids orally 2–3 h before the induction of anesthesia. However, only 35% of the respondents said their institutions had a policy in place allowing a light breakfast 6 h before elective surgery. Nevertheless, only 3% of the responders said they would cancel the operation if a patient actually arrived at the facility after consuming a light breakfast, such as toast and tea 6 h before elective surgery, 32% would delay surgery to later that day, and 65% would proceed without delay. We concluded that most anesthesiologists practicing outpatient anesthesia in the United States have already changed their practice pattern to conform to the recent recommendations of the American Society of Anesthesiologists task force on preoperative fasting time. Implications Findings of this national survey conducted among active members of the Society for Ambulatory Anesthesia may encourage anesthesiologists throughout the world to take a more liberal attitude toward allowing clear liquids 2–3 h and a light breakfast 6 h before an elective surgery in healthy patients.

The role of irrigation in the development of hypothermia during laparoscopic surgery

OBJECTIVES Our purpose was to determine the incidence and etiology of hypothermia during laparoscopic surgery and to evaluate the role of irrigation fluid temperature. STUDY DESIGN A prospective randomized study was performed of 35 women undergoing operative laparoscopy under general anesthesia who received surgical irrigation fluid either at ambient temperature or warmed to 39 degrees C. The core body temperature was determined with use of both an esophageal sensor and a tympanic membrane sensor and was expressed as the change from baseline. Additional data collected included age, height, weight, amount of irrigation fluid and intravenous fluid used, room temperature, length of anesthesia, and amount of carbon dioxide used for pneumoperitoneum. RESULTS Hypothermia occurred in 94% of all patients, with no difference in incidence between the groups. The minimal core temperature was lower in the ambient temperature group (-1.7 degrees +/- 0.2 degrees C) than in the warmed fluid group (-1.0 degrees +/- 0.2 degrees C). Of the variables measured, length of anesthesia and the amount of ambient temperature fluid alone explained the drop in core temperature. CONCLUSION Hypothermia is extremely common in laparoscopic surgery and is related to the length of anesthesia and the use of ambient temperature irrigation fluid. The use of warmed irrigation fluid can decrease, but not eliminate, this drop in core temperature.

Intraoperative ketorolac has an opioid-sparing effect in women after diagnostic laparoscopy but not after laparoscopic tubal ligation.

Ketorolac tromethamine (Toradol Registered Trademark) is a parenteral, nonsteroidal antiinflammatory drug that is being extensively used to provide postoperative analgesia.This study evaluated whether intraoperative ketorolac would act synergistically with fentanyl to decrease postoperative analgesic requirements in outpatients undergoing gynecologic procedures. The patients studied were adult ASA physical status I or II females scheduled for diagnostic laparoscopy (DL) (n = 80) or laparoscopic tubal ligation (TL) (n = 46). Each patient received fentanyl 2 micro gram/kg intravenously (IV) before induction, followed by a standardized propofol anesthetic and 2 mL of saline or ketorolac 60 mg IV in a randomized double-blind fashion 30 min before the anticipated end of the operative procedure. Patients were assessed for postoperative pain via a 10-cm visual analog scale (VAS) (0 = no pain; 10 = severe pain) before analgesic treatment in the postanesthesia care unit (PACU). Severe postoperative pain (VAS of 5 or more) was treated with incremental doses of fentanyl, 25-50 micro gram IV by a blinded PACU nurse. Ibuprofen or acetaminophen with codeine was administered for pain control once the patient tolerated oral medications. This study showed that intraoperative ketorolac (60 mg IV) with fentanyl (2 micro gram/kg IV) administered at the induction of anesthesia resulted in significant opioid sparing and a diminution in pain in the DL sample but not in the TL sample. The analgesic regimen was also associated with a lower incidence of nausea and vomiting and resulted in earlier discharge, which was not seen after TL. These results demonstrate that pain after TL is far greater than that after DL, which suggests that these procedures should be considered separately when designing analgesic regimens. (Anesth Analg 1996;82:732-7)

Low dose intravenous infusion technique with ketamine. Amnesic, analgesic and sedative effects in human volunteers.

Low dose ketamine is a relatively new technique. The recommended doses vary considerably. It was therefore decided to establish the minimum dose of ketamine required to produce satisfactory analgesia, sedation and amnesia in 50% of a population of adult volunteers. Twenty adult volunteers aged 20 to 42 years were the subjects of the study. Twenty minutes following intravenous (iv) pre‐treatment with 0·3 mg of atropine and 0·2 mg/kg of diazepam each volunteer received a bolus of ketamine 1·0 mg/kg iv followed by ketamine iv infusion at the rate of either0·5 mg/kg/hour(10cases) or 1·0 mg/kg/hour (10 cases). The grade of sedation was determined on a scale of 1–5 and the frequency of amnesia was assessed using visual memory cards. Analgesia was determined by pin prick.

Propofol versus thiamylal-enflurane anesthesia for outpatient laparoscopy.

STUDY OBJECTIVE To determine whether propofol anesthesia differs from thiamylal-enflurane anesthesia in induction characteristics, intraoperative hemodynamics, postoperative side effects, and postoperative psychomotor function recovery. DESIGN A randomized, double-blind, two-group study. SETTING A large university hospital with gynecologic outpatient operations performed in an integrated operating room suite. PATIENTS Sixty adult women (ASA physical status I or II) undergoing an outpatient gynecologic laparoscopic operation with an anesthesia time of approximately 60 minutes. INTERVENTIONS No pharmacologic premedication. Pretreatment with intravenous droperidol 0.6 mg and sufentanil 0.2 micrograms/kg before induction of anesthesia. Anesthesia was induced with either thiamylal 4 mg/kg (Group 1) or propofol 2.5 mg/kg (Group 2). Anesthesia was maintained with either nitrous oxide (N2O) and enflurane, 2-0.5% inspired concentrations; (Group 1) or with a continuous infusion of propofol 200-100 micrograms/kg/min and N2O (Group 2). MEASUREMENTS AND MAIN RESULTS In psychomotor function tests (Trieger dot test and p-deletion test) administered preoperatively and postoperatively, no difference was found between the groups. No difference was found in induction time, although significantly more patients reported pain after the propofol injection, or in intraoperative hemodynamics (mean arterial pressure and heart rate). Immediate recovery time (emergence from anesthesia) and intermediate recovery time (ambulation, oral intake, and discharge time) were significantly shorter after propofol anesthesia. Fewer postoperative side effects, such as nausea and vomiting, were reported after propofol anesthesia. CONCLUSIONS Induction and maintenance of anesthesia with propofol were comparable to those with thiamylal-enflurane, except patients experienced more pain on injection after propofol. Both immediate and intermediate recovery were more rapid after propofol anesthesia compared with enflurane-based anesthesia.

Physostigmine fails to reverse clinical, psychomotor, or EEG effects of lorazepam.

Physostigmine salicylate (2.0 mg) or 0.9% NaCl (2.0 ml) was administered intravenously in a double-blind fashion to adult volunteers in an attempt to reverse the effects of a 0.05-mg/kg dose of lorazepam given intravenously 30 min earlier. No other medication affecting the central nervous system was given. No differences were observed between the two groups with regard to the frequency of amnesia, psychomotor impairment, or EEG changes during a period of 4 h. The only significant difference in the level of sedation between the two groups was observed 60 min into the study. This difference is attributed to the high incidence of nausea and vomiting that occurred at that time exclusively in one group. Time to complete recovery was the same in both groups. However, physostigmine, not saline, was associated with a high incidence of muscarinic and sympathetic stimulating effects. The results obtained indicate that at the dose used, physostigmine is of no clinical value in treating sedation induced by lorazepam.