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PubMedDate not supplied

[Total intravenous anesthesia with ketamine and the condition of the higher psychic function in the early and remote postoperative periods].

Influence of total intravenous anesthesia with ketamine on the higher psychic function was studied, immediately after surgery and in the remote postoperative period, in 143 patients with different typological properties of the nervous system after a scheduled surgery--supravaginal uterectomy in fibromyoma of the uterine body. The authors defined 6 groups of patients with different typological properties of the nervous system. Persistent impairment of the higher nervous functions were established, immediately after surgery and in the remote postoperative period, in patients with a weak nervous system, biased nervous balance towards excitation, and with lability of nervous processes. Total intravenous anesthesia with ketamine, when used in patients with the robust nervous system, biased nervous balance towards excitation, and with lability of nervous processes, caused changes in the higher nervous functions and an intensified level of nervous-and-psychic loads, which were unstable and were arrested by the 30th postoperative day. The use of such anesthetic scheme was found to be inadvisable in the above groups of patients. The described impairments were not registered when total intravenous anesthesia was used in patients with a balanced nervous system irrespective of its type, a biased nervous balance towards inhibition and with inertness of nervous processes. The above anesthetic management is acceptable for such patients.

Adult↗

PubMed2006

Org 25969 (sugammadex), a selective relaxant binding agent for antagonism of prolonged rocuronium-induced neuromuscular block.

BACKGROUND: Org 25969 is a cyclodextrin compound designed to reverse a rocuronium-induced neuromuscular block. The aim of this study was to explore the efficacy, dose-response relation and safety of Org 25969 for reversal of a prolonged rocuronium-induced neuromuscular block. METHODS: Thirty anaesthetized adult patients received rocuronium 0.6 mg kg(-1) as an initial dose followed by increments to maintain a deep block at a level of <10 PTCs (post-tetanic counts) recorded every 6 min. Neuromuscular monitoring was carried out using accelerometry, in a train-of-four (TOF) mode using TOF-WatchSX. At recovery of T2, following at least 2 h of neuromuscular block, patients received their randomly assigned dose of 0.5, 1.0, 2.0, 4.0 or 6.0 mg kg(-1) of Org 25969. Anaesthesia and neuromuscular monitoring were continued for a minimum period of 30 min after Org 25969 administration. The main end-point of the study was the time to achieve a sustained recovery of TOF ratio to 0.9. Patients were followed up for 7 days after anaesthesia. RESULTS: The results showed a dose-related decrease in the average time taken to attain a TOF ratio of 0.9 from 6:49 (min:s) with the 0.5 mg kg(-1) dose to 1:22 with the 4.0 mg kg(-1) dose. Weighted non-linear regression analysis showed the fastest achievable time to TOF ratio of 0.9 to be 1:35. Org 25969 produced no major adverse effects. CONCLUSION: Org 25969 effectively reversed a deep and prolonged neuromuscular block induced by rocuronium. The effective reversal dose appears to be 2-4 mg kg(-1).

Adult↗

PubMed2002

Isoflurane dosage for equivalent intraoperative electroencephalographic suppression in patients with and without epidural blockade.

UNLABELLED: We conducted a prospective, randomized, controlled trial to establish the effect of epidural blockade on isoflurane requirements for equivalent intraoperative electroencephalographic (EEG) suppression. Fifty patients undergoing abdominal hysterectomy received combined epidural and general anesthesia or general anesthesia alone with isoflurane and alfentanil. Isoflurane was administered by computer-controlled closed-loop feedback to maintain an EEG 95% spectral edge frequency of 17.5 Hz, a target chosen on the basis of a pilot study. In epidural patients, end-tidal isoflurane concentration (FE'(ISO)) was 0.19% smaller (95% confidence interval [CI], -0.32% to -0.06%; P < 0.01), mean arterial blood pressure was 17 mm Hg lower (95% CI, -24 to -9 mm Hg; P < 0.0001), and body temperature was 0.4 degrees C lower (95% CI, -0.7 to 0 degrees C; P < 0.05) than in controls. EEG bispectral index (BIS) was 4 points higher (95% CI, 1 to 7; P < 0.05). EEG median frequency and heart rate were similar in both groups. Epidural patients were 76% more likely (95% CI, 58% to 94%; P < 0.001) to require metaraminol for hypotension and were 28% more likely (95% CI, 3% to 53%; P < 0.05) to require glycopyrrolate for bradycardia. After surgery, the time to eye opening in epidural patients was 2.3 min shorter (95% CI, -4.2 to -0.5 min; P < 0.05). Time to eye opening correlated better with FE'(ISO) in the last 30 s of anesthesia (FE'(ISO) = 0.07 x time to eye opening + 0.31; r(2) = 0.59; P < 0.0001) than with BIS from the same period (BIS = 64 - 1.25 x time to eye opening; r(2) = 0.22; P < 0.001) (P < 0.0001). To maintain similar intraoperative spectral edge frequency, patients receiving combined epidural and general anesthesia require 21% less isoflurane than those receiving general anesthesia alone. This smaller isoflurane dose is associated with faster emergence from anesthesia. IMPLICATIONS: The dose of general anesthetic required to maintain similar intraoperative suppression of brain electrical activity is 21% less in patients with nerve blockade than in those without. This dose reduction results in faster waking times in patients with nerve blockade, which may reflect lighter intraoperative anesthesia. The dose of general anesthetic required to maintain similar intraoperative suppression of brain electrical activity is 21% less in patients with nerve blockade than in those without. This dose reduction results in faster waking times in patients with nerve blockade, which may reflect lighter intraoperative anesthesia.

Adult↗

PubMed1992

Recollections of general anaesthesia: a survey of anaesthesiological practice.

In order to identify the factors to which patients attach importance when undergoing general anaesthesia, 678 patients were retrospectively asked about their recollections of previous anaesthetics during routine preoperative screening over a period of 14 months. The most frequently mentioned recollections concerned the post-anaesthetic period, followed by recollections of the induction of anaesthesia. From the post-anaesthetic period, nausea/vomiting and drowsiness were most often cited. The number of anaesthetics previously undergone had no influence on the reports of the two most frequently mentioned complaints. The rate of nausea/vomiting in this series was 21.0%. The number of patients reporting nausea/vomiting following an anaesthetic has not changed over the years. The last 250 patients were asked to assess the quality of their anaesthetics on a 5-point scale. More than a quarter of the patients were not satisfied with the anaesthesia. No correlation was found between the assessment of the anaesthesia and complaints about nausea/vomiting and drowsiness. The possible role of psychological factors in the origin of complaints about anaesthesia is discussed.

Adolescent↗

PubMed2003

Local, regional, or general anaesthesia in groin hernia repair: multicentre randomised trial.

BACKGROUND: In specialised centres, local anaesthesia is almost always used in groin hernia surgery; whereas in routine surgical practice, regional or general anaesthesia are the methods of choice. In this three-arm multicentre randomised trial, we aimed to compare the three methods of anaesthesia and to determine the extent to which general surgeons can reproduce the excellent results obtained with local anaesthesia in specialised hernia centres. METHODS: Between January, 1999, and December, 2001, 616 patients at ten hospitals, were randomly assigned to have either local, regional, or general anaesthesia. Primary endpoints were early and late postoperative complications. Secondary endpoints were duration of surgery and anaesthesia, length of postoperative hospital stay, and time to normal activity. Analysis was by intention to treat. FINDINGS: Intraoperative tolerance for local anaesthesia was high. In the early postoperative period, local anaesthesia was superior to the other two types with respect to almost all endpoints. At 8 days' and 30 days' follow-up, there were no significant differences between the three groups. Although the mean duration of surgery was longer, the total anaesthesia time-ie, time from the start of anaesthesia until the patient left the operating room-was significantly shorter than it was for regional or general anaesthesia. INTERPRETATION: Local anaesthesia has substantial advantages compared with regional or general anaesthesia, such as shorter duration of admission, less postoperative pain, and fewer micturition difficulties. The favourable results obtained with local anaesthesia in specialised hernia centres can, to a great extent, be reproduced by general surgeons in routine surgical practice.

Anesthesia Recovery Period↗

PubMed1991

[Anesthesia for single-day orthopedic surgery].

During the period 1 January 1989 to 31 December 1989, a total of 1,004 patients were submitted to outpatient single-day surgery in Aalborg Hospital. As fas as possible, the patients were anaesthetized with propofol (Diprivan)/alfentanil (Rapifen) and oxygen and atmospheric air. This form of anaesthesia was found to be rapid and suitable for single-day surgery. 8.1% of the patients required admission for further observation, 2.3% of these on account of anaesthesiological complications. It is concluded that, by means of meticulous planning, it is possible to carry out ambulant anaesthesia and surgery and, employing limited staff resources, it has proved possible to reduce the waiting time for outpatient intervention to 10-12 weeks.

Adolescent↗

PubMed1990

A survey of general anaesthesia and sedation in dental practice in two cities.

Using a postal questionnaire, the use of general anaesthesia and sedation in general dental practice in two cities over a 4-week period was investigated. Questionnaires were sent to a random sample of one in five dental practitioners in Bristol and Sheffield, and an 82% response rate was attained. More practices in Sheffield administered general anaesthesia than those in Bristol. The differences between the facilities provided are discussed. Equipment and facilities have improved since a larger survey was described in 1976, but the use and availability of monitoring equipment has changed little since then. The results reflect the decline in the use of general anaesthesia in dental practice seen nationally. The survey provides an insight into the current anaesthetic services provided in general dental practice in two cities, both of which contain dental hospitals, and provides a basis for the design of a protocol for a further national survey.

Anesthesia Recovery Period↗

PubMedDate not supplied

Propofol reduces prolonged outpatient PACU stay. An analysis according to surgical procedure.

This study compared the effects of propofol anesthesia and nonpropofol general anesthetics on duration of stay in the postanesthesia care unit (PACU) for prolonged drowsiness or nausea and vomiting following various surgical procedures. A group of 512 patients undergoing general anesthesia for a variety of outpatient surgical procedures over a 6-month period received general anesthesia with nitrous oxide, with or without propofol. Data collected from PACU records included type of surgical procedure and duration in the PACU of more than 2 hours owing to drowsiness or nausea and vomiting. Overall, patients who received propofol with nitrous oxide experienced less frequent drowsiness, nausea, or vomiting compared with patients who received nonpropofol anesthetic agents (drowsiness 12% vs 31%; nausea/vomiting 3% vs 25%). For patients undergoing gynecologic surgery, propofol anesthesia yielded an 8% incidence of prolonged PACU stay, compared with 41% for nonpropofol techniques. Similar results occurred for orthopedic surgery (15% vs 35%); for ear, nose, or throat procedures (30% vs 75%); and for ophthalmic surgery (18% vs 71%), but not for oral surgery (44% vs 64%). Most same-day surgery patients benefit from administration of propofol for induction and maintenance of anesthesia. Advantages include a decreased likelihood of a prolonged stay in the PACU as a result of drowsiness or nausea and vomiting.

Adult↗

PubMed2004

Preemptive ketamine during general anesthesia for postoperative analgesia in patients undergoing laparoscopic cholecystectomy.

AIM: Preemptive analgesia is currently in use in the management of postoperative pain and no more under search. The administration of ketamine as intraoperative analgesic agent is well-known since a long time; the analgesic properties of this drug are related to its actions as a non-competitive N-methyl-D-aspartate receptors antagonist; these receptors present an excitatory function on pain transmission and this binding seems to prevent or reverse the central sensitisation of every kind of pain, including postoperative pain. In literature, the use of this anesthetic for the preemptive analgesia in the management of postoperative pain is controversial; for this reason the aim of our study was the clinical evaluation of preemptive perioperative analgesia with low-doses ketamine. METHODS: This trial involved 40 patients undergoing laparoscopic cholecystectomy, with the same surgical operator; postoperative analgesia was performed with the intraoperative administration of ketamine (0.7 mg/kg) or tramadol (15 mg/kg). A randomized, double-blind study was performed; after an inhalatory/analgesic general anesthesia (sevofluorane + remifentanyl) the postoperative-pain control was clinically evaluated through algometric measurements (Visual Analog Scale, Verbal Rating Scale, Pain Intensity Difference); supplemental doses of tramadol were administered if required, also to quantify the adequacy of analgesia, and adverse effects were evaluated. RESULTS: The results show that preemptive intraoperative analgesia with ketamine produces a good analgesia at the awakening, despite low duration (approximately 1 hour), and upgrades the analgesic effect of tramadol in the postoperative period. Among the adverse effects, some (for example nausea) were related to the administration of both analgesics and to the kind of surgery, others (hallucinosis, nystagmus, photophobia, psychomotor excitation, psychotic symptoms) were due to ketamine, and others (respiratory depression and hypotension) could be related to tramadol. Although the adverse effects due to ketamine are more numerous than those related to tramadol, the second could potentially be more dangerous. CONCLUSION: Our study suggests that preemptive low-doses ketamine is able to produce an adequate postoperative analgesia and increases the analgesic effect of tramadol; furthermore, ketamine adverse effects could be reduced by intraoperative administration of benzodiazepines and/or antiemetic drugs, or by the association of ketamine and a peripheral analgesic (ketorolac).

Adult↗

PubMed2004

Patient-controlled sedation with propofol in minor oral surgery.

PURPOSE: We sought to evaluate the benefits of patient-controlled sedation with propofol for minor oral surgery. PATIENTS AND METHODS: After instructions were given on how to use the technique, 28 male and 24 female patients sedated themselves during minor oral surgery with titrating 18-mg bolus doses of propofol with a lockout period of 1 minute. RESULTS: Surgery lasted from 5 to 29 minutes; 28 patients were moderately and 17 were deeply sedated. Seven patients were oversedated. All of those who were oversedated responded to commands within 1 minute of being unresponsive and continued to obtain increments of propofol. Vital signs were stable in all patients even during oversedation. Eighteen patients were talkative, and 17 complained of pain along the vein. Operating conditions were good in 38, fair in 12, and poor in 2. The majority, 48 patients, were relaxed, and 47 were willing to undergo the sedation technique again. Ten had total, 22 had partial, and 20 had no amnesia. CONCLUSIONS: Relaxed patients, good operating conditions, and quick recovery of oversedated patients without unstable vital signs provide evidence that propofol has favorable pharmacokinetic and pharmacodynamic properties for patient-controlled sedation. This study also highlights the importance of close monitoring of patients during patient-controlled sedation.

Adolescent↗

PubMed2000

The effects of midazolam and flumazenil on psychomotor function and alertness in human volunteers.

OBJECTIVE: To investigate the effect of midazolam and flumazenil on psychomotor function and alertness in human volunteers. DESIGN: Randomised, double-blind, cross over study. METHODS: Intravenous flumazenil was administered to sedated and non-sedated healthy human volunteers, in doses typical of those used clinically to induce sedation with midazolam and for reversal with flumazenil. Subjective assessment of alertness and objective measures of psychomotor function using light reaction time and the Maddox wing were made over a 1 hour period. RESULTS: Seven males and seven females each attended four experimental sessions. Psychomotor function was impaired by midazolam but there was some individual variation to this response. All sedated subjects receiving flumazenil had significantly improved alertness and psychomotor function when compared with those subjects who received placebo. Mean alertness (P < 0.01) and light reaction time (P < 0.05) showed significant improvement and returned to baseline by 60 minutes. Stability also showed significant improvement (P < 0.05) but did not return to baseline by 60 minutes. There was no significant effect on psychomotor function or alertness when the antagonist flumazenil was administered in the absence of the agonist midazolam. CONCLUSION: An earlier discharge time based on subjective assessment of alertness is not advocated for patients whose intravenous midazolam sedation is reversed with flumazenil.

Adult↗

PubMed2004

Improvement of pain treatment after major abdominal surgery by intravenous S+-ketamine.

UNLABELLED: The use of intraoperative racemic ketamine for pain prevention after abdominal surgery is controversial. We compared one preincisional i.v. injection of S(+)-ketamine with its preincisional and repeated intraoperative use in 45 patients undergoing surgery with epidural and general anesthesia. S(+)-ketamine is a new drug formulation that contains the more potent S(+)-stereoisomer of ketamine. Patients were randomized to receive placebo, 0.5 mg/kg preincisional S(+)ketamine, or 0.5 mg/kg preincisional and 0.2 mg/kg intraoperative S(+)-ketamine repeated at 20-min intervals. In the postoperative period, epidural ropivacaine (2 mg/mL; 0.12 mL.kg(-1).h(-1)) was infused for pain therapy. Patients who received repeated S(+)-ketamine reported smaller pain scores than those who received placebo after awakening and 3 and 6 h later (P < or = 0.05). Fewer patients with repeated S(+)-ketamine required additional analgesics than those with placebo (P < or = 0.05). Cumulative consumption of additional diclofenac and dextropropoxyphene at 24 h was less after single (P < 0.05) and repeated (P < 0.05) S(+)-ketamine versus placebo. After awakening, patients who received repeated S(+)-ketamine reported being in a better mood than those in the other groups (P < 0.05). No psychotomimetic side effects were noted. In conclusion, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone. IMPLICATIONS: After major visceral surgery, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone.

Abdomen↗

PubMed1991

[Effect of peroperative analgesia on immediate postoperative oxygen consumption].

Oxygen consumption in the immediate postoperative period was assessed in a series of twelve patients undergoing maxillofacial surgery, randomly assigned to two groups (n = 6 for each). The anaesthetic protocol was the same in all patients: premedication with flunitrazepam 30 micrograms.kg-1, induction with flunitrazepam 20 micrograms.kg-1, fentanyl 5 micrograms.kg-1, thiopentone 5 mg.kg-1, pancuronium bromide 80 micrograms.kg-1, and maintenance during the first three hours with flunitrazepam 10 micrograms.kg-1.h-1 and pancuronium 0.03 micrograms.kg-1.h-1. All the patients were given a continuous infusion of fentanyl during the whole length of the surgery: in Group I (GI), 3 micrograms.kg-1.h-1 and in Group II (GII), 1 microgram.kg-1.h-1. The patients in Group II were also given enflurane 1.2 +/- 0.3 vol %. During the immediate postoperative period, the parameters studied were measured by means of an Engström Metabolism Calculator at the 15th, 30th, 45th, 60th, 120th and 240th minutes, and at the time of extubation. In GII, postoperative heart rate and lactic acid levels were higher than in GI (p less than 0.05). Both groups had oxygen consumption values greater than theoretical resting levels. However, postoperative oxygen consumption was greatly increased in GII with respect to GI during the first 4 hours (p less than 0.01). The respiratory quotient was greater in GI than in GII at the end of the study (p less than 0.05). These data indicate that the intraoperative analgesic technique influences postoperative oxygen consumption. A dose of fentanyl of 3 micrograms.kg-1.h-1 is more efficient than one of 1 microgram.kg-1.h-1 associated with enflurane.

Adult↗

PubMed2001

Onset and duration of action of rocuronium--from tracheal intubation, through intense block to complete recovery.

BACKGROUND: The primary objective of this study was to establish the relation between the post tetanic count (PTC) and the time to reappearance of the first response (T1) in train-of-four (TOF) nerve stimulation following rocuronium 0.6 mg/kg, 0.9 mg/kg, and 1.2 mg/kg. The secondary objective was to evaluate the intubation conditions after 1 min. METHODS: One hundred and eight patients were randomised to one of three doses of rocuronium: 0.6, 0.9 or 1.2 mg/kg. Tracheal intubation was performed at 60 s by a blinded investigator. During propofol, fentanyl, midazolam anaesthesia the neuromuscular block was monitored by mechanography using TOF stimulation every 12 s. At 6 min intervals, a tetanic stimulation (50 Hz) was applied for 5 s preceded and followed by a 30 s period of 1 Hz stimulation until the reappearance of T1. RESULTS: There was a significant difference in recovery following the high dose and the two lower doses. The relation between time (min) to reappearance of T1 (t) and PTC can be expressed as follows: t(0.6 and 0.9 mg/kg)(min)=18.8-6.46 PTC and t(1.2 mg/kg)(min)=26.1-9.12 PCT. T1 was seen at a mean PTC level of 8 or 9 in all three groups. The intubation conditions were graded as excellent or good in all patients except in two patients following the 0.6 mg/kg dose of rocuronium. CONCLUSION: The PTC method can be used to predict the time to first response to TOF nerve stimulation during intense rocuronium induced neuromuscular blockade. The relation between PTC and the time to T1 was prolonged after 1.2 mg/kg compared with 0.6 mg/kg and 0.9 mg/kg. No further improvement in intubation conditions at 60 s was evident by increasing the rocuronium dose from 0.9 mg/kg to 1.2 mg/kg.

Adolescent↗

PubMed2004

Dixyrazine for the prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy.

BACKGROUND: The study assessed the efficacy and safety of dixyrazine, an alternative neuroleptic drug to droperidol, in the prophylaxis of postoperative nausea and vomiting (PONV). METHODS: A total of 197 patients scheduled for laparoscopic cholecystectomy under general anesthesia were randomized to receive either dixyrazine 10 mg or placebo double-blinded at the end of surgery. Scores pertaining to PONV episodes, analgetic supply, rescue medication, adverse events and patient satisfaction were collected over the first 2 h in the PACU and the next 22 h in the ward. RESULTS: The incidence of PONV over the entire 24-h period was reduced from 32% in the placebo group to 13% in the dixyrazine group (P< or =0.004). The incidence of nausea in the first 2 h was reduced from 15% in the placebo group to 4% in the dixyrazine group (P< or =0.02) and from 12% to 5% in the next 22 h. The incidence of emetic episodes was not different between the two groups. Postoperative shivering was significantly less prevalent in the dixyrazine than in the placebo group (2% vs. 13%; P< or =0008), and opioid analgesics were required significantly less often (61% vs. 75%; P< or =0.01). No significant adverse effects were observed. Patient satisfaction was similar in both groups. CONCLUSION: Prophylactic dixyrazine is an effective, safe, and cheap antiemetic drug for laparoscopic cholecystectomy without involving any significant adverse events.

Analgesics, Opioid↗

PubMedDate not supplied

Three balanced anesthetic techniques for neuroanesthesia: infusion of thiopental sodium with sufentanil or fentanyl compared with inhalation of isoflurane.

STUDY OBJECTIVE: To compare emergence from anesthesia and the hemodynamic and respiratory depressant effects of thiopental sodium infusion plus sufentanil or fentanyl with those of isoflurane as the primary component of a balanced technique for neuroanesthesia. DESIGN: Randomized, double-blind, prospective study. SETTING: University hospital and its affiliated Veterans Affairs Medical Center. PATIENTS: Thirty patients undergoing elective craniotomy for aneurysm or tumor. INTERVENTIONS: Thiopental with infusion of sufentanil 0.1 microgram/kg/hr, thiopental with infusion of fentanyl 1 microgram/kg/hr, or inhalation of 0.25% to 2% isoflurane as the major component of a balanced anesthesia technique that included nitrous oxide (N2O) and vecuronium (potency ratio of sufentanil to fentanyl, 10:1). MEASUREMENTS AND MAIN RESULTS: Intraoperative stress response (as indicated by intraoperative hypertension) was said to be the percentage of time the patient required administration of an antihypertensive drug, measuring from the first dose of thiopental to discontinuation of N2O at the end of the procedure, excluding any period of induced hypotension. Rapidity of emergence was measured by the number of minutes from discontinuation of N2O to first opening of the eyes on command. Adequacy of spontaneous ventilation was evaluated by determining partial pressure of arterial carbon dioxide 1, 2, and 3 hours after discontinuation of N2O. Extent of vasoactive drug administration for control of intraoperative hypertension (as determined by the clinicians caring for the patients) was described by minutes of vasodilator infusion and milligrams of propranolol or labetalol administered. The frequency of postoperative hypertension was defined as the number of patients in each group who required medication for postoperative hypertension. No significant differences in variables were found for thiopental/sufentanil, thiopental/fentanyl, or isoflurane when these drugs were used with N2O and vecuronium. CONCLUSIONS: Any one of these balanced anesthetic techniques appears appropriate for craniotomy.

Adult↗

PubMed2000

Electroencephalographic indices related to hypnosis and amnesia during propofol anaesthesia for cardioversion.

Most previous studies which have assessed the depth of anaesthesia using the Bispectral Index (BIS) have used multi-agent anaesthetics with relatively slow induction and recovery times. Elevation of electroencephalographic (EEG) Beta/Alpha Ratio has been linked to onset of midazolam amnesia. Propofol anaesthesia for cardioversion in 19 patients enabled us to profile the changes in BIS and Beta/Alpha Ratio during a short, single-agent anaesthetic with a relatively rapid induction and recovery period. BIS values did not alter significantly through onset of amnesia and hypnosis as compared with awake values. Cardioversion occurred over a wide range of BIS values (38 to 94), with recovery at a median BIS value of 79. We observed the BIS to lag about 60 s behind the clinical situation (termed BIS60). The BIS60 more closely tracked the clinical level of consciousness, showing statistically significant differences from the uncorrected BIS. (amnesia (median BIS60 = 82, P = 0.02), hypnosis (median BIS60 = 67, P = 0.01), eye opening (median BIS60 = 90, P = 0.001)). An early EEG Beta/Alpha Ratio peak occurred at a mean of 4.6 s (SD = 16.6) after clinical amnesia onset and a late peak at a mean 58 s (SD = 144) after eye opening. There was no significant EEG response to cardioversion. We conclude that: (1) in rapidly changing conditions, the value of the BIS most accurately reflects the level of consciousness of the patient about 60 s in the past, and (2) the onset and offset of propofol-induced amnesia commonly corresponds to a peak in Beta/Alpha Ratio of the EEG.

Adult↗

PubMed1995

The role of sevoflurane in outpatient anesthesia.

Sevoflurane appears to have several properties that make it an attractive alternative to the currently available anesthetics for outpatient anesthesia. The relative low solubility of sevoflurane, as well as an impressive lack of airway irritation, makes it a very useful anesthetic for inhalation induction of anesthesia. This feature is likely to make sevoflurane a population choice for pediatric outpatient anesthesia. For adult outpatients, the relatively low solubility of sevoflurane permits rapid alterations in alveolar concentration during the maintenance period (even when administered at relatively low flow rates of 2-3 L/min), thereby improving control of the depth of anesthesia. Low solubility should also allow for a more predictable emergence from anesthesia (versus isoflurane), thereby facilitating patient turnover in a busy ambulatory surgery center. The commercial development of sevoflurane has been slow because of concerns regarding the potential toxicity of its metabolites and breakdown products (24). However, the large body of clinical experience from Japan and the worldwide Phase II and III clinical development programs suggests that these concerns may be unfounded. The short duration of exposure in the outpatient setting should further decrease the risk of nephrotoxicity. The relatively low solubility of sevoflurane will facilitate its use with total gas flow rates of 2-3 L/min. In the final analysis, clinicians will have to balance the cost of sevoflurane (versus halothane, enflurane, isoflurane, and desflurane) against its potential advantages in the ambulatory surgery population. Although the search for anesthetics that are more ideally suited for use in the outpatient setting will continue, sevoflurane clearly represents a step in the right direction (3).

Adult↗