Remifentanil versus propofol as adjuncts to regional anesthesia. Remifentanil 3010 Study Group.

STUDY OBJECTIVE: To compare the safety and efficacy of remifentanil and propofol as adjuncts to regional anesthesia in patients undergoing orthopedic or urogenital surgery. DESIGN: Prospective, randomized study. SETTING: Multicenter university hospitals. PATIENTS: 107 ASA physical status I, II, and III adult patients who underwent orthopedic or urogenital surgery with axillary, ankle, or spinal block. INTERVENTIONS: Patients were randomized to receive either an infusion of remifentanil 0.2 microg/kg/min or propofol 100 microg/kg/min 5 minutes before nerve block placement. The infusions were decreased by 50% on block completion, increased by 50% for patient discomfort, and decreased by 50% for hypoventilation (< 8 breaths/min) or hemodynamic instability. MEASUREMENTS AND MAIN RESULTS: Pain, discomfort, anxiety, and sedation were assessed by both patient and investigator. Vital signs and adverse events were recorded. Fewer patients in the remifentanil group experienced pain during block placement (6%), and were oversedated (7%) than patients in the propofol group (23% and 26%, respectively; p < 0.05). Hypoventilation during and after block placement (21% and 25%, respectively) and nausea and vomiting during and after block placement (60% and 21%, respectively) were more common in the remifentanil group than in the propofol group (0% and 3%; 17% and 6%, respectively; p < 0.05). The incidence of hypoventilation in remifentanil-treated patients was higher in patients over 65 years of age (p < 0.05), but was transient, resolving within minutes of discontinuing the infusion. CONCLUSIONS: At the doses studied, remifentanil was more effective than propofol in minimizing pain without producing excessive sedation. Remifentanil was associated with more transient respiratory depression and short-term nausea. Our findings indicate that the initial remifentanil rate should be 0.1 microg/kg/min (50% lower than the study's initial rate) and should be further decreased an additional 50% in the elderly to minimize adverse effects.

Prolonged surgery increases the likelihood of admission of scheduled ambulatory surgery patients.

STUDY OBJECTIVE: To identify variables influencing the likelihood of unanticipated admission following scheduled ambulatory surgery. DESIGN: Retrospective case-controlled chart review study. SETTING: A large academic tertiary care hospital. PATIENTS: 8,549 ASA physical status I, II, III, and IV patients who underwent scheduled ambulatory surgery in 1991. MEASUREMENTS AND MAIN RESULTS: Of the 8,549 patients, 216 were admitted, with complete medical record information available for 167 of the admitted patients. The most common reasons for admission among the 167 were surgical (43%), anesthetic (28%), and medical (17%) complications. Odds for admission following long surgery (of at least 60 minutes) were 7.5 times (p < 0.001) greater than following short surgery (under 60 minutes). Among long cases, independent variables influencing admission were: general anesthesia [odds ratio 20.8; 95% confidence interval (CI) 4.4 to 45.6], and monitored anesthesia care or regional anesthesia (combined odds ratio 8.3; 95% CI 1.7 to 40.8). ASA physical status and patient age did not significantly influence admission rate for long cases. For short cases, patients over 65 years (odds ratio 5.6; 95% CI 2.6 to 12.0), ASA physical status III or IV (odds ratio 4.8; 95% CI 2.0 to 11.6), use of general anesthesia (odds ratio 4.7; 95% CI 1.5 to 14.2), and monitored anesthesia care or regional anesthesia (odds ratio 3.1; 95% CI 1.0 to 10.1) independently influenced the likelihood of admission. Type of surgery and gender had no detectable effect on admission. CONCLUSIONS: Surgery duration of 60 minutes or longer was the most important predictor of unanticipated admission following scheduled ambulatory surgery.

Propofol permits tracheal intubation but does not affect postoperative myalgias.

STUDY OBJECTIVE: To determine the effect of propofol without succinylcholine on intubating conditions and postoperative myalgias in ambulatory surgical patients undergoing general anesthesia. DESIGN: Prospective, double-blind, randomized study. SETTING: Ambulatory surgery adult patients. PATIENTS: 56 ASA physical status I and II adult patients undergoing general endotracheal anesthesia. INTERVENTIONS: Group 1 patients received thiamylal plus succinylcholine, Group 2 patients received propofol plus succinylcholine; and Group 3 patients received propofol plus saline. All patients received fentanyl, lidocaine, and nitrous oxide plus isoflurane in oxygen. MEASUREMENTS AND MAIN RESULTS: Incidence and severity of fasciculations, tracheal intubating conditions, and myalgias on the first and third postoperative days were measured. Propofol did not affect the incidence or severity of fasciculations following succinylcholine, or the incidence of myalgias. Of patients who received propofol without succinylcholine, intubation was successful in 85%. CONCLUSIONS: Propofol did not affect the incidence or severity of postoperative myalgias following succinylcholine.

Surgical patients' attitudes regarding participation in clinical anesthesia research.

We designed a questionnaire to identify the factors influencing both day of admission surgery (DAS) and ambulatory (AMB) patients in their decision whether to participate in and give informed consent for clinical anesthesia research. On the day of surgery, 276 patients were approached to complete a questionnaire and a visual analog scale (VAS) to assess anxiety. The data collected were observational and are presented as percentages for each group (DAS and AMB). One hundred eighty-two patient (60 DAS and 122 AMB) completed questionnaires. Both DAS and AMB patients desired 20-30 min to read a consent form. Preferred conditions for enrollment by both groups were as follows: interview at the time of preadmission testing; after consulting with their physician; in a private setting while dressed in street clothes; and with assurance that the investigator would also participate in the study, if eligible. Unacceptable conditions were as follows: research associated with any risk and interview in the operating room holding area. All patients responded that they were capable of making the decision whether to participate in research on the day of surgery. Most AMB and DAS patients found it acceptable to be recruited on the day of surgery, if approached appropriately.

Recovery advantages of regional anesthesia compared with general anesthesia: adult patients.

The data support but do not conclusively prove, that RA results in a superior recovery compared with GA. However, several questions need to be answered. Even though the patient may leave the hospital or surgicenter sooner after RA, how does the patient treat pain at home once the block has "worn off"? Since short-acting sedatives and opioids are so commonly used with RA, to what extent is recovery due to them and to what extent is recovery due to the RA alone? Many of the studies examining beneficial effects of RA have been poorly conducted, combining RA with GA and producing inconclusive results. Anesthetic techniques need to be carefully compared to determine whether they are equal in quality, efficiency, and cost. Finally, to determine whether RA is cost-effective, future studies involving ambulatory patients with a focus on outcome and well-being need to be conducted.

Attenuation of suxamethonium myalgias. Effect of midazolam and vecuronium.

We studied the incidence of fasciculations and postoperative myalgias in 100 female outpatients who had laparoscopy under thiopentone, N2O, isoflurane anaesthesia. Four groups of 20 patients each were pretreated with saline (group 1), tubocurarine 0.05 mg/kg (group 2), vecuronium 0.006 mg/kg (group 3), or midazolam 0.025 mg/kg (group 4), followed by suxamethonium 1.5 mg/kg. Group 5 received only vecuronium 0.1 mg/kg as relaxant (no suxamethonium). Fasciculations were graded, and postoperative myalgias rated on the first and third postoperative days. In groups 1-5 the incidence of fasciculations was 95, 15, 25, 95 and 0%; the incidence of myalgias on the first day after operation was 70, 45, 65, 75 and 60%, and on the third day after operation 20, 5, 20, 20, and 5%, respectively. We conclude that pretreatment with vecuronium, but not midazolam, decreases the incidence of fasciculations after suxamethonium (p less than 0.05) and that in this patient population, postoperative myalgias appear to be unrelated to the use of suxamethonium.

A defasciculating dose of d-tubocurarine causes resistance to succinylcholine.

Forty-four patients, ASA physical status I or II, undergoing thiamylal, fentanyl, N2O/O2 anaesthesia were studied to determine the dose-response to succinylcholine (Sch) without prior defasciculation (24 pt - Group 1), or three minutes following d-tubocurarine (dTC), 0.043 mg.kg-1 (20 pt - Group 2). The individual log dose-logit response curve for each patient was determined using a cumulative dose plus infusion technique and integrated EMG monitoring of the first dorsal interosseous muscle. The mean (+/- SEM) ED50, ED90 and ED95 values for Sch in Group 1 were 0.13 +/- 0.01, 0.19 +/- 0.01 and 0.22 +- 0.01 mg.kg-1, and in Group 2 were 0.16 +/- 0.01, 0.25 +/- 0.01 and 0.29 +/- 0.02 mg.kg-1, respectively. The mean ED values in Group 2 were significantly greater than the equivalent values in Group 1 (P less than 0.05). Compared with values in Group 1, ED values in Group 2 represented mean increases of 23, 32, and 32 per cent, respectively. These pharmacodynamic data indicate that the dose of Sch needs to be increased by 32 per cent following a defasciculating dose of dTC 3 mg.70 kg-1 (0.043 mg.kg-1).