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PubMed1996

[Clinical experience of laryngeal mask airway combined with continuous intravenous propofol infusion during general anesthesia].

BACKGROUND: Propofol's greatest attributes are its pharmacokinetic properties which result in a rapid, clear emergency and lack of cumulative effects even after prolonged administration. It is a drug of popular choice for the maintenance of general anesthesia. The laryngeal mask airway (LMA), originally described by Dr. Brain is now a good alternative as the airway management technique. Because of its high success rate in securing a clinically acceptable airway in anesthetized patients, LMA has been proposed as a practical airway and conveyer for general anesthesia. This study was designed to observe and evaluate the feasibility of propofol infusion combined with N2O for maintenance of anesthesia, with a LMA as airway and conveyer during general anesthesia. METHODS: Sixty patients, ASA class I-II, aged 15-59 years, were selected for this study. They were scheduled for upper-limb orthopedic surgeries in supine position. No patient was premedicated. Intraoperative monitoring included electrocardiography, pulse oximetry, end-tidal carbon dioxide and automatic non-invasive blood pressure. The agents for induction of anesthesia included atropine 0.01 mg/kg, atracurium 5 mg, fentanyl 2-3 micrograms/kg, 2% lidocaine 1.5-2 mg/kg, propofol 2 mg/kg, and succinylcholine 1-1.5 mg/kg, all of which were given intravenously in sequence. After that laryngeal mask airway (LMA) was inserted. The position of LMA was confirmed by even undulation of chest wall and breathing sound. Anesthesia was then maintained with nitrous oxide in 40% oxygen and continuous propofol infusion. The pumping rate was set to start at 6 mg/kg/h. Muscle relaxation was achieved by intravenous tracrium given intermittently. All patients were mechanically ventilated with a ventilator incorporated to the anesthesia machine. The ventilator was set to give a tidal volume of 8 ml/kg at a rate of 12-14/min. At the end of the operation, the propofol infusion and nitrous oxide were simultaneously discontinued. The effect of muscle relaxant was antagonized by atropine 1.0 mg and neostigmine 2.5 mg intravenously. The LMA was removed while the patient was awake and able to open mouth at request. They were followed 24 h postoperatively for inquiring intraoperative awareness and other complaints. RESULTS: No patient was noted to experience awareness during the intraoperative period. Regarding LMA insertion, success in the first attempt was seen in 55 patients (90.2%). Success in the second attempt was seen in 5 patients (8.2%). Failure was encountered in one patient (1.6%). The average time of emergence was 92 +/- 3.4 min. The average rate of speed of propofol infusion was 6.29 +/- 0.97 mg/kg/h. CONCLUSIONS: The combination of propofol infusion and N2O with laryngeal mask as airway and recovery was a good alternative in administration of general anesthesia.

Adolescent↗

PubMed1998

Conscious awareness during general anaesthesia: patients' perceptions, emotions, cognition and reactions.

We interviewed 45 patients, who answered advertisements (n = 21) or were referred by colleagues (n = 24), about their experience of intraoperative awareness using a standardized questionnaire. Auditory perceptions, hearing sounds or voices were mentioned by all patients (45 of 45): 33 of 45 patients understood and recalled conversations; 21 of 45 patients had visual perceptions; 12 of 21 recognized things or faces; 29 of 45 patients felt being touched; three patients had the sensation of moderate pain; and eight patients were in severe pain. Patients' feelings were mostly related to paralysis (27 of 45), helplessness (28 of 45), anxiety and fear (22 of 45); 18 were in severe panic. All patients (45 of 45) recognized the situation as a real event: 22 of 45 patients experienced unpleasant after effects; 11 suffered from anxiety and nightmares; and three developed post-traumatic stress disorder syndrome and required medical treatment. Twenty of 45 patients were especially attentive to emotionally relevant remarks on their own person, their disease and the course of their operation. The accuracy of sensory perception indicates a very high level of cognitive performance of patients during intraoperative awareness.

Adult↗

PubMed1999

Awareness during anesthesia: a closed claims analysis.

BACKGROUND: Awareness during general anesthesia is a frightening experience, which may result in serious emotional injury and post-traumatic stress disorder. We performed an in-depth analysis of cases from the database of the American Society of Anesthesiologists Closed Claims Project to explore the contribution of intraoperative awareness to professional liability in anesthesia. METHODS: The database of the Closed Claims Project is composed of closed US malpractice claims that have been collected in a standardized manner. All claims for intraoperative awareness were reviewed by the reviewers to identify patterns of causation and standard of care. Logistic regression analysis was used to identify independent patient and anesthetic factors associated with claims for recall during general anesthesia compared to other general anesthesia malpractice claims. RESULTS: Awareness claims accounted for 79 (1.9%) of 4,183 claims in the database, including 18 claims for awake paralysis, i.e., the inadvertent paralysis of an awake patient, and 61 claims for recall during general anesthesia, ie., recall of events while receiving general anesthesia. The majority of awareness claims involved women (77%), younger than 60 yr of age (89%), American Society of Anesthesiologists physical class I-II (68%), who underwent elective surgery (87%). Most (94%) claims for awake paralysis represented substandard care involving errors in labeling and administration, whereas care was substandard in only 43% of the claims for recall during general anesthesia (P < 0.001). Claims for recall during general anesthesia were more likely to involve women (odds ratio [OR] = 3.08, 95% confidence interval [CI] = 1.58, 6.06) and anesthetic techniques using intraoperative opioids (OR = 2.12, 95% CI = 1.20, 3.74), intraoperative muscle relaxants (OR = 2.28, 95% CI = 1.22, 4.25), and no volatile anesthetic (OR = 3.20, 95% CI = 1.88, 5.46). CONCLUSIONS: Deficiencies in labeling and vigilance were common causes for awake paralysis. Claims for recall during general anesthesia were more likely in women and with nitrous-narcotic-relaxant techniques.

Adult↗

PubMed2005

An analysis of intraoperative recall of awareness in Thai Anesthesia Incidents Study (THAI Study).

OBJECTIVES: This study aimed to analyze intraoperative awareness using database of Thai Anesthesia Incidents Study (THAI Study) with regard to frequency, contributing factors, preventive and corrective strategies. MATERIAL AND METHOD: Details of intraoperative recall of awareness were recorded prospectively by attending anesthesiologists or nurse anesthetists in standardized record forms during February 1, 2003 to July 31, 2004. Participating hospitals included 7 university hospitals, 5 tertiary care hospitals, 4 secondary care hospitals, and 4 primary care hospitals. All data were analyzed to identify contributing factors, preventive and corrective strategies. RESULTS: Among 126078 general anesthetized cases, there were 99 cases of intraoperative recall of awareness. Awareness was found in female patients more than male patients (63% versus 37%). The majority of patients had ASA PS 1 and 2. Cardiac, obstetric, and lower abdominal surgery were involved in anesthesia awareness more than other type of surgery. Patients experiencing awareness reported sound (62%), pain (51%), feeling operated without pain (33%), and paralysis (25%). There was slight impact of anesthesia awareness in Thai patients (only 13% had temporary emotional stress and 13% had mild anxiety) despite small percentage of proper management by reassurance and psychiatric consultation (15%). The contributing factors included inadequate knowledge (67%), inadequate medication dosage (44%), and inadequate care from inexperience (11%). Awareness incidents were documented to be preventable in 36% of patients and partially preventable in 38% of patients. The corrective strategies included guideline practice (30%), additional training (28%), quality assurance activity (19%), and improved supervision (16%). CONCLUSION: The incidence of intraoperative recall of awareness in this study was 0.08%. Patients reported sound, pain, feeling operated without pain, and paralysis. Corrective strategies included guideline practice, additional training, quality assurance activity, and improved supervision.

Adolescent↗

PubMed1996

The effect of midazolam at two plasma concentrations of hemodynamics and sufentanil requirement in coronary artery surgery.

OBJECTIVES: In this study, the hemodynamics and sufentanil requirement were compared at two midazolam target plasma concentrations in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Prospective, randomized study. SETTING: University hospital, single institution. PARTICIPANTS: Patients undergoing CABG. INTERVENTIONS: Patients were randomly assigned to receive midazolam at a target plasma concentration of 150 ng/mL (group 1; n = 10) or 300 ng/mL (group 2; n = 10). Sufentanil infusion was titrated to maintain hemodynamic stability, defined as mean arterial pressure within 15% of baseline values. All patients received preoperative beta-blocking agents. Arterial blood samples of midazolam and sufentanil were analyzed by high-performance liquid chromatography and radioimmunoassay, respectively. MEASUREMENTS AND MAIN RESULTS: The mean dose of sufentanil (7.5 +/- 1.7 microgram/kg in group 1 v 7.2 +/- 2.5 micrograms/kg in group 2) did not differ. There were no significant differences in hemodynamics between the groups in the period before or after cardiopulmonary bypass (CPB). Before CPB, in two patients in each group, hypertension was controlled with sufentanil only. One patient in group 1 required a vasodilator in addition to sufentanil. No ischemic events occurred before CPB. After CPB, one patient in group 2 required a vasodilator to control hypertension. Two patients in group 2 required treatment with nitroglycerin for myocardial ischemia. Stable plasma concentrations of sufentanil and midazolam were obtained during and after CPB. The midazolam infusion was continued in both groups at a rate of 1.25 micrograms/kg/min during the first 4 postoperative hours. The time to awakening did not differ between the groups (100 +/- 58 minutes in group 1 v 173 +/- 147 minutes in group 2) nor did the plasma concentrations of midazolam (96 +/- 28 ng/mL v 108 +/- 42 ng/mL) at the time of awakening. Intraoperative awareness was not reported. CONCLUSION: In patients undergoing CABG, good hemodynamic control with a similar incidence of hemodynamic interventions was observed at midazolam target plasma concentrations of 150 and 300 ng/mL when coadministered with sufentanil. The sufentanil requirement was identical in both groups. This study suggests that a midazolam plasma concentration of 150 ng/mL is sufficient to provide satisfactory hemodynamic control and to avoid intraoperative awareness.

Adjuvants, Anesthesia↗

PubMed1996

[Incidence and quality of dreaming during anesthesia with propofol in comparison with enflurane].

UNLABELLED: Since the introduction of propofol into clinical practice, dreaming during general anaesthesia has been frequently reported with this drug. We investigated the incidence and character of these dreams with regard to distinction from intraoperative awareness and in comparison with habitual dreams or dreams during general anaesthesia with enflurane. METHOD: A total of 230 patients (ASA I-II) undergoing minor elective surgery were randomly assigned to one of two groups. Both groups received the same premedication (1 mg flunitrazepam) the previous evening. After induction using etomidate 2 mg/kg, anaesthesia in group I was maintained using 0.8%-1.5% enflurane supplemented in the sense of "balanced anaesthesia" with fentanyl, vecuronium, and nitrous oxide. Anaesthesia in group II was induced with propofol 2 mg/kg. After a saturation phase of approximately 10 mg/kg.h, 5-6 mg/kg.h was administered for maintenance supplemented by fentanyl, Vecuronium, and N2O as in group I. Interviews were conducted preoperatively, just after recovery from anaesthesia, and 24 h later. We inquired about preoperative fears or concerns, sensory perceptions, and the incidence and character (pleasant, unpleasant, indifferent) of habitual dreams. After recovery the patients were asked if they had had any conscious perceptions, whether they believe them to be dreams or reality, and repeated the preoperative questions as to common feelings and the character of sensory perceptions. RESULTS: The two groups were not entirely comparable due to the distribution of sex and age, but we did not find any differences in preoperative grades of fear and incidence of dreams. Of the propofol patients, 60% dreamed intraoperatively versus 11% in the enflurane group. No evidence of any intraoperative awareness was found. Because of the low incidence of dreams in the enflurane group, a comparison of detailed information between the groups could not be provided. Except for 1, all patients in the propofol group had very pleasant dreams compared to their habitual dreams (4.5% in the enflurane group). One day after surgery 37% of all patients in the propofol group remembered having dreamed intraoperatively. We did not found any correlation to the incidence of habitual dreaming, preoperative fear, age, sex, duration of anaesthesia, or total dose of propofol. Furthermore, intraoperative dreams differed from habitual dreams in character and content. CONCLUSIONS: We conclude that sensory experiences during propofol anaesthesia are not stimulus-related perceptions or awareness, but dreams similar to normal ones. In view of the absence of clear signs of stimulus-related response, we presume that dreaming is a specific side effect of propofol. Because of the absence of difficulties, dreaming during propofol anaesthesia appears not to be a disadvantage with regard to the quality of anaesthesia.

Adult↗

PubMed1996

Midazolam and awareness with recall during total intravenous anaesthesia.

PURPOSE: A double-blind study was undertaken to evaluate the influence of graded doses of midazolam on propofol infusion requirements, recovery characteristics and the quality of recovery, associated with propofol/alfentanil/O2 total intravenous anaesthesia (TIVA). METHODS: Ninety ASA Class I and II subjects scheduled for arthroscopic knee surgery were randomly allocated to receive either placebo (Group PLAC), or midazolam doses of 15, 30 or 45 micrograms.kg-1 (Groups M-15, M-30 and M-45, respectively). Anaesthesia was induced and maintained with propofol (infused initially at 100 micrograms.kg-1.min-1, and adjusted there after according to anaesthetic depth) and alfentanil (loading dose of 20 micrograms.kg-1, followed by infusion at 0.5 microgram.kg-1. min-1). Postoperatively, times to awakening, recovery, and discharge were evaluated, in addition to psychometric evaluations using the Trieger Dot Test (TDT). RESULTS: The study was discontinued prematurely, as six patients unexpectedly experienced intraoperative awareness with recall (4/21 = 19.1% of patients with PLAC vs 2/69 = 2.9% of patients in the midazolam groups, P < 0.04). Induction requirements of propofol were found to be lower in the M-30 and M-45 groups when compared with PLAC (P < 0.05), whereas propofol infusion requirements were similar among groups. Times to awakening and discharge from the Recovery Room and Day Care Unit, as well as TDT scores, were no greater in any midazolam group than in PLAC. CONCLUSIONS: Midazolam 30-45 micrograms.kg-1 decreases the amount of propofol required for anaesthetic induction, without influencing recovery profiles or patient discharge times from the Day Care Unit. Despite careful modulation of the propofol infusion rate, six patients unexpectedly experienced intraoperative awareness with recall, with the lowest incidence occurring in those groups where patients had received midazolam.

Adolescent↗

PubMed2006

Processed EEG and patient outcome.

The era of research evaluating clinical outcomes associated with processed electroencephalogram (EEG) monitoring began with the first randomized trial of bispectral index monitoring (BIS) performed as part of the clearance process for approving routine clinical use of the BIS monitor by the United States Food and Drug Administration. Subsequent to this initial investigation, numerous other clinical investigations have demonstrated that the use of processed EEG monitors as an additional method of patient assessment and an aid to anaesthetic dosing can decrease anaesthetic usage and hasten recovery times. Because of the presumed association between anaesthetic effect and EEG changes, it is not surprising that the additional research has focused on the impact of processed EEG monitoring on postoperative outcomes and perioperative safety especially the prevention of intraoperative awareness.

Anesthesia↗

PubMedDate not supplied

Awareness under anesthesia and the development of posttraumatic stress disorder.

Failure of general anesthesia to render a patient insensate, termed "awareness," is estimated to affect between 40,000 and 140,000 patients in the US each year. This study investigated the occurrence of post-traumatic stress disorder (PTSD) in subjects who reported a past episode of intraoperative awareness. We inquired about intraoperative and postoperative experiences and studied the relationship between various surgical experiences and currently meeting the diagnosis of PTSD. Sixteen postawareness subjects and 10 postgeneral anesthesia controls completed the Clinician Administered PTSD Scale (CAPS), a standardized clinical rating scale for PTSD, and a questionnaire about peri-operative experiences. Nine of 16 subjects (56.3%), a mean of 17.9 postoperative years, and no controls met diagnostic criteria for current PTSD (X(2)= 8.6, df = 1, P<.01). Common intraoperative experiences included an inability to communicate, helplessness, terror, and pain. Postawareness patients had significant postoperative distress related to feeling unable to communicate, unsafe, terrified, abandoned and betrayed. Perioperative dissociative experiences predicted having current PTSD. Being conscious during surgery is a traumatic event that may result in developing chronic PTSD. Further studies should include prospective designs of prevalence and long-term psychological, social, and overall health effects, and ways of preventing and treating awareness-induced PTSD.

Adult↗

PubMed1990

[Anesthesia, awareness and wakefulness].

Drugs used in anesthesia do not always produce the expected neurophysiological results. By studying those cases in which the reappearance of intraoperative awareness is most common, an attempt was made to estimate how many and which levels of cerebral function could be identified. Four levels were recognised: awareness with or without memory, and wakefulness with or without dreams. These conditions are related to greater or lesser cortical activity. They can be identified using Tunstall's technique and by carefully interviewing the patient immediately after the operation.

Adult↗

PubMedDate not supplied

EEG-controlled "overdosage" of anesthetics in a patient with a history of intra-anesthetic awareness.

In spite of the ever-growing pharmacologic arsenal available for induction and maintenance of anesthesia, to our knowledge no treatment regimen exists that will provide full protection against intraoperative awareness. To date, no single monitoring technique is able to detect awareness or predict recall. Although the frequency of these complications is rare, the occurrence of any such event can be very distressful for the patient. Based on our clinical experience with a patient with a history of recall and a marked resistance to benzodiazepines, we present electroencephalogram-based anesthetic management as a technique to address this difficult problem.

Adult↗

PubMed1986

Wakefulness during cesarean section after anesthetic induction with ketamine, thiopental, or ketamine and thiopental combined.

Thirty-six pregnant women (ASA class I or II) at term who underwent general anesthesia and cesarean section received either ketamine, 1 mg/kg (n = 12); thiopental, 4 mg/kg (n = 13); or a combination of ketamine, 0.5 mg/kg, and thiopental, 2 mg/kg (n = 11). A blood pressure cuff inflated to 250 mm Hg isolated one arm from the effects of succinylcholine so that awareness during anesthesia could be assessed by asking the patient to move her hand. Although only one patient receiving ketamine responded to commands during anesthesia, 46% of patients receiving either thiopental or the combination responded to commands intraoperatively. No patient hallucinated, the incidence of dreams was low (11%), and no postoperative dysphoria was noted. Three patients (8%) had postoperative recall of intraoperative awareness; one had received thiopental and two the combination. Maternal intraoperative cardiovascular responses among the groups were similar, as were umbilical blood gas values, newborn Apgar scores, and neonatal neurobehavioral test scores at 4 and 24 hr. Ketamine more effectively blocked maternal responsiveness to commands and strong stimuli during the first few minutes after anesthetic induction for cesarean section than did thiopental or a combination of thiopental and ketamine, each at a lower dose.

Adult↗

PubMed2005

Awareness during anesthesia in children: a prospective cohort study.

During routine adult anesthesia, the risk of awareness is 0.1%-0.2%. No recent studies have reported the incidence in children. Altered pharmacology and differing anesthesia techniques suggest that the incidence may differ in children. In this prospective cohort study, we determined the incidence of awareness during anesthesia in children. Eight-hundred-sixty-four children aged 5-12 yr who had undergone general anesthesia at The Royal Children's Hospital were interviewed on 3 occasions to determine the incidence of awareness. The awareness assessment was nested within a larger study of behavior change after anesthesia. Reports of suspected awareness were sent to four independent adjudicators. If they all agreed, a case was classified as true awareness. Twenty-eight reports were generated. There were 7 cases of true awareness, for an incidence of 0.8% (95% confidence interval, 0.3%-1.7%). Only one aware child received neuromuscular blockers, compared with 12% in the nonaware group. No aware child reported distress, and no substantial difference was detected in behavior disturbance between aware (20%) and nonaware (16%) children. The data provide some evidence that, like adults, children are also at risk of intraoperative awareness. Although the cause remains unclear, anesthesiologists should be alerted to the possibility of awareness in children.

Anesthesia↗

PubMed2004

Monitoring depth of anaesthesia: is it worth the effort?

In this review paper, the authors critically analyse the use of a number of depth of anaesthesia monitors in light of the most recent literature and their own clinical experience. There appears to be increasing evidence that anaesthesia depth monitors reduce the incidence of unexpected intraoperative awareness and also that they improve the quality of anaesthesia. Proper use of these monitors necessitates background knowledge about the physiology of the loss of consciousness, the type of variable recorded and processed by the monitoring devices, the factors that might interfere with recording and the limits of use. The information provided by anaesthesia depth monitors is detailed and relationships with clinical practice are established to provide the reader with key features for optimal use of those monitors and correct interpretation of data. Practitioners and patient's knowledge and expectations regarding this matter, as well as the cost-benefit relationship are also discussed.

Anesthesia, General↗

PubMed2003

Awareness during surgery.

OBJECTIVE: Patients who experience awareness under surgery may suffer from the post-traumatic stress disorder with its long-lasting psychological damage. Furthermore, there are also media attention and legal consequences. In spite of understanding its causes, it is still occurring worldwide and there are no reports of awareness in the Saudi medical literature. This prospective study was conducted to determine the incidence of awareness when its causes are eliminated and to record patient satisfaction. METHODS: Surgical patients >4 years old (ASA I-III) admitted to the Armed Forces Hospital, Wadi Al-Dawasir, Kingdom of Saudi Arabia, between October 1998 and November 2002 were included in the study. Patients were given a premedicant with an amnesic effect. Anesthetic equipment with a built-in end-tidal anesthetic gas monitor was checked preoperatively. Minimal anesthetic concentrations of vapors were delivered and monitored. Intraoperative analgesia was provided whenever appropriate. Patients were closely observed for signs of intraoperative awareness under general anesthesia. All patients were interviewed within 24 hours postoperatively on the occurrence of awareness and service satisfaction. RESULTS: There were 4368 patients admitted to the study. Their ages ranged from 14-104 years (mean 40.2 years). All patients were interviewed in the postoperative period. There was no report of awareness during surgery and patient satisfaction score was 100%. CONCLUSION: Preoperative and intraoperative anesthetic attention to patients presented for surgery, together with the use of modern anesthetic delivery units possessing facilities for monitoring anesthetic gases, and the provision of good analgesia are the most important combination in eliminating awareness during surgery.

Adolescent↗

PubMed2003

Awareness under general anesthesia.

General anesthesia aims to eliminate patients' awareness of excruciating pain during surgery. Nevertheless, rare occurrences of patient awareness continue because the problem is not yet completely preventable. One study puts the incidence of awareness at 0.18% for patients receiving muscle relaxants and at 0.10% for patients not given relaxant drugs. Awareness experiences frighten patients and impact their implicit and explicit memories in ways that can leave a lifetime of residual emotional and psychological problems ranging from sleep disturbances, nightmares, and daytime anxiety that may subside with time to development of post-traumatic stress disorder. Most anesthetists monitor depth of anesthesia by assessing intraoperative hemodynamic responses to surgical stimuli--an approach questioned by some authors. Several depth-of-anesthesia monitors are available, but there is no ideal monitor that is 100% reliable. This review provides an overview of literature that reports findings associated with the monitoring and occurrence of intraoperative awareness. These studies indicate assessment methods that can be trusted when we provide general anesthesia and what measures can be taken to prevent recall by patients under general anesthesia.

Anesthesia, General↗

PubMed1991

[Conscious and unconscious acoustic perception during general anesthesia].

The possibility of processing sensory information during general anesthesia and the ability to recall it postoperatively is of major ethical, medical and even theoretical importance. Auditory stimuli especially are perceived intraoperatively and remembered postoperatively. Neuropsychological experiments indicate that sensory information can be processed and recalled both at a conscious and at an unconscious level. Therefore, we have to distinguish between explicit and implicit memory. Explicit memory is characterized by an active and conscious recall of space- and time-related events, i.e., episodes in a person's life. In contrast, implicit memory recalls passively and unconsciously without being related to space and time, i.e., language and general knowledge. Experimental results from amnesic patients indicate that these two memory systems work independently from each other. Even when explicit memory is grossly impaired the function of the implicit memory may still be completely preserved. Various studies on intraoperative awareness show that explicit memory is widely eliminated during general anesthesia. The incidence of conscious awareness that can be actively recalled postoperatively is reported to be 1-3%. In contrast, the implicit memory function can be partially preserved. When implicit memory tasks or hypnosis are employed, traces of unconscious memory of intraoperative auditory information can be shown in 20-30% of the patients. These observations are of important clinical relevance, because the unconsciously recalled information about the intraoperative procedure may have a negative influence on the patient's postoperative recovery and well-being. So far it is still not known which anesthetics most reliably suppress auditory perception and conscious and unconscious memory during the intraoperative period. Therefore, future studies should focus on several different points. The anesthetic state should be defined exactly and the functional state of the auditory modality should be monitored when auditory information is presented to the patients. The recollection of intraoperative events should be investigated using implicit memory tests, because these are regarded as more sensitive than explicit memory tests.

Anesthesia, General↗

PubMed2005

New anesthesia techniques.

Advances in anesthesia involve refinements in understanding, technique, and technology. These refinements have led to better control of the anesthetic state, effective anesthesia for a wider variety of situations, and the ability to bring sicker patients to the operating room. Although the molecular mechanisms underlying the general anesthetic state are unknown, evidence suggests a specific, receptor-based effect. This concept has allowed anesthesiologists to treat anesthetic end points of immobility, lack of awareness, and autonomic control separately. It is likely that anesthesia and naturally occurring sleep interact physiologically. New, processed EEG monitors may allow anesthesiologists to titrate more finely anesthetic dose, with possible benefits in terms of speed of recovery and detection of intraoperative awareness. Since the 1990s, new anesthetic drugs (propofol, desflurane/sevoflurane, cisatracurium) have enhanced greatly control of the anesthetic state. The new intravenous anesthetic agent dexmedetomidine offers sedation with preserved respiration and cognitive function. Although its role has yet to be defined fully, it currently plays a role in ICU sedation and monitored anesthesia care. New anesthesia ventilators have better monitoring and better flow delivery at high airway pressures. These improvements significantly narrow the performance gap between anesthesia and ICU ventilators. In patients with COPD, pulmonary hypertension, or severe hypoxemia, heliox may improve gas flow, and NO may reduce pulmonary vascular resistance and improve oxygenation.

Anesthesia, General↗