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At least 163 records · Page 9Linked to original sources
PubMed1995

The effects of anesthesia with increasing end-expiratory concentrations of sevoflurane on midlatency auditory evoked potentials.

We studied midlatency auditory evoked potentials (MLAEP) during general anesthesia with increasing end-expiratory concentrations of sevoflurane in 12 patients scheduled for elective gynecologic surgery. After oral premedication with 20 mg clorazepate dipotassium, anesthesia was induced with etomidate (0.2 mg/kg intravenously [IV]). Vecuronium (0.1 mg/kg) was given for neuromuscular block, and controlled ventilation with sevoflurane in 100% O2 was instituted. Auditory evoked potentials were recorded in the awake state and during anesthesia with end-expiratory steady-state concentrations of 0.5, 1.0, 1.5, and 2.0 vol% of sevoflurane on vertex (positive) and mastoids on both sides (negative). Latencies of peaks V, Na, Pa, Nb, and P1 (ms) and amplitudes of Na/Pa, Pa/Nb, and Nb/P1 (microV) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia with increasing end-expiratory concentrations of sevoflurane, the latency of the brainstem response V increased slightly. In contrast, MLAEP showed marked dose-dependent, statistically significant increases in the latencies of Na, Pa, Nb, and P1 and decreases in the amplitudes of Na/Pa, Pa/Nb, and Nb/P1. Under 2 vol% of sevoflurane, MLAEPs were severely attenuated or abolished. Based on these observations, > or = 1.5 vol% sevoflurane should suppress phenomena such as auditory perceptions, intraoperative wakefulness, and awareness.

Adult↗
PubMed1990

[Middle-latency auditory evoked potentials during high-dose opioid analgesia].

Neuropsychological and neurophysiological investigations indicate that a 30-40 Hz oscillatory brain mechanism is necessary for the adequate uptake and processing of elementary successive sensory events. An oscillatory component of that particular frequency range can be observed in the mid-latency auditory evoked potential (MLAEP). It is suppressed under non-specific anesthetic agents (agents not acting on specific structures of the brain or receptors). Opioids produce analgesia, sedation, and are also used for induction and maintenance of general anesthesia. The effect of opioids on MLAEP has not yet been examined sufficiently. Because intraoperative wakefulness and awareness is not rarely observed under high-dose opioid analgesia, the effect of general anesthesia with fentanyl on MLAEP and auditory evoked neuronal 30-40 Hz oscillation was studied. Following informed consent in 20 patients scheduled for elective surgery, anesthesia was induced with fentanyl 0.01-0.02 mg/kg i.v. Auditory evoked potentials (AEP) were recorded before and 5 min after the start of general anesthesia over the vertex (positive) and mastoids on both sides (negative). Auditory clicks were presented binaurally at 70 dBnHL with a frequency of 9.3 Hz. Using the electrodiagnostic system Pathfinder I (Nicolet Co.), 1000 successive stimuli were averaged over a 100-ms post-stimulus period and analyzed off-line. Latencies of the peaks V, Na, and Pa were measured. By Fast-Fourier Transform-analysis corresponding power spectra were calculated to analyze energy portions of the AEP frequency components. In the awake state AEP showed an oscillatory component between 20- and 100-ms post-stimulus latency. Corresponding power spectra indicated a dominant 30-40 Hz frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

[Anesthetic management for microlaryngeal surgery with high frequency jet ventilation and intravenous application of pentazocine and propofol].

Microlaryngeal surgery was performed with total intravenous anesthesia using pentazocine and propofol in 20 patients. The patients were paralyzed by suxamethonium infusion and ventilated by high frequency jet ventilation via the laryngoscope. In place of the opioid analgesics commonly used in TIVA for microlaryngeal surgery, pentazocine was given. All but one of the patients received pentazocine 15 m.g. intramuscularly as a premedication and then another 15 m.g. intravenously for induction of anesthesia. Average time of surgeries was 33.6 minutes. Average doses of pentazocine and suxamethonium given during surgeries were 369 m.g. and 286 m.g., respectively. This technique allowed stable anesthesia to be achieved with rapid postoperative recovery, without serious complications like intraoperative return of awareness.

Adjuvants, Anesthesia↗
PubMed2006

Attitudes of anaesthetists to awareness and depth of anaesthesia monitoring in the UK.

BACKGROUND AND OBJECTIVE: Awareness with postoperative recall of intraoperative events is a rare but serious complication of general anaesthesia. This survey investigated the attitude of anaesthetists in the UK to awareness and depth of anaesthesia monitoring. METHODS: Questionnaires were sent to 4927 consultant anaesthetists in 285 hospitals in the UK in September 2004. The responses were recorded in an electronic database, summarized and compared with the results of studies performed in Australia and the USA. RESULTS: The response rate was 44%. When judged against published awareness rates, anaesthetists underestimated the incidence of awareness in their own practice (median 1: 5000). One-third of respondents have dealt with patients who have experienced intraoperative recall. The majority of anaesthetists perceived awareness as a minor problem on an 11-point scale (modal score 2, median score 3, IQR 2-5). Eighty-six percent of anaesthetists considered clinical signs unreliable but 91% felt that measurement of end-tidal anaesthetic agent concentration reduces the likelihood of awareness. The majority of anaesthetists would use a monitor at least some of the time if one was available to them. Overall, the attitudes of anaesthetists in the UK, USA and Australia are remarkably similar. CONCLUSIONS: Anaesthetists tend not to view awareness as a serious problem. Although most accept that clinical signs are unreliable indicators of awareness, few believe that monitors of anaesthetic depth should be used for routine cases.

Adult↗
PubMed2000

[Intraoperative awakening: report of a case in pediatric surgery].

Intraoperatory awakening or awareness can be defined as recovering of conscience during general anesthesia. We report such a case happened in a 11 year-old boy during a hypospadias repair. After anesthetic education he related intraoperatory conscience without pain, anxiety, displeasing symptoms or long-term psychoconductal distress. We remark fisiopathology, diagnostic and preventive aspects of this rare event in pediatric surgery.

Anesthesia, General↗
PubMedDate not supplied

Stenosis of the carotid artery and thrombosis of the internal contralateral carotid. Analysis of surgical results in thirty patients.

Carotid thrombosis and stenosis of the contralateral axis is a hemodynamic situation which results in reduced blood supply to the brain, and consequently in risk of transitory or permanent ischemic episodes. In fact, 40% of patients are symptomatic for TIA or Little Stroke and 50% of them will develop a complete stroke. Of the 255 patients who underwent TEA, over a period of 5 years, only 30 presented the above mentioned bilateral feature. A continuous electroencephalographic recording (EEG) was intraoperatively carried on for cerebral monitoring, as well as mean residual arterial pressure (MRAP), and according to variations in these parameters Javid's shunt was used in 50% of cases. No death was recorded either during surgery or hospitalization, while 2 transitory post-operative neurological deficits (6.6%) in correspondence to the stenotic vessel, and a late permanent deficit contralateral to the stenosis were reported. We believe TEA of the stenotic carotid artery to be a rational choice considering the great incidence of strokes on the stenotic side (Grillo, 1975) and the greater benefit for patients with symptoms resulting from the occluded carotid (Riles, 1980), who account for 46.6% of our case histories. We are convinced that surgery is an absolute indication in this particular category of patients, even at the cost greater intraoperative risks, provided it is carried out by an experienced surgical team well aware of problems involved in intraoperative cerebral monitoring.

Carotid Artery Diseases↗
PubMed2005

Cataract surgery in Fuchs' dystrophy.

PURPOSE OF REVIEW: Corneal decompensation after cataract surgery can occur in patients with Fuchs' endothelial dystrophy. This paper reviews the pathogenesis of corneal edema in Fuchs' dystrophy, the preoperative and perioperative risk factors for corneal endothelial cell loss during cataract surgery, and indications for cataract surgery alone or cataract surgery combined with keratoplasty for patients with visually significant cataracts and Fuchs' dystrophy. RECENT FINDINGS: Accelerated loss of corneal endothelial cells in Fuchs' dystrophy is multifactorial, with apoptosis and altered gene regulation of aquaporin proteins playing a role. Preoperative factors contributing to decreased endothelial cell count include age, sex, diabetes, a history of ocular trauma or inflammation, and contact lens wear. Intra-operative measures shown to protect endothelial cells include the use of the soft-shell viscoelastic technique for very dense cataracts, efficient cataract removal techniques (phaco-chop, use of oscillatory handpiece), and surgery by an experienced surgeon. A triple procedure should be performed with preoperative corneal epithelial decompensation and considered with preoperative pachymetry greater than 640 mum. Otherwise, it is reasonable to attempt cataract surgery alone with proper patient education. SUMMARY: Fuchs' dystrophy is a progressive disorder. Cataract surgery in the setting of Fuchs' dystrophy can be performed successfully, especially when the surgeon is aware of the preoperative and intraoperative factors that affect the number of functioning endothelial cells. All patients should be aware of the progressive nature of this disease and the possibility of keratoplasty at some point in their lifetime.

Cataract↗
PubMed2003

Case report: intraoperative left common iliac occlusion in a scheduled 360-degree spinal fusion.

STUDY DESIGN: This is a case report of a left common iliac artery occlusion identified as an intraoperative complication during a planned (combined anterior interbody and posterior fusion) 360 degrees spinal fusion. OBJECTIVE: The purpose of this report was to document the occurrence of this rare complication during a planned 360 degrees fusion and to increase the awareness of this potential intraoperative vascular complication. SUMMARY OF BACKGROUND DATA: Several cases of left iliac artery occlusion after anterior spinal surgery have been reported, but there has been no reported case of intraoperative iliac artery occlusion identified during a planned 360 degrees spinal fusion. METHODS: The patient was a 46-year-old woman with chronic low and mid back pain and left leg pain for several years. She was a 2-pack-a-day cigarette smoker for 30 years. She was diagnosed with internal disc disruption at L3-L4 and L4-L5, unresponsive to nonoperative treatment, and was scheduled for a 360 degrees spinal fusion. During the anterior procedure, the left iliac vessels were retracted with a Wiley retractor during the discectomy and fusion. It was noted that there was no pulse in the left common iliac artery as the anterior procedure neared completion. Intraoperative Doppler showed the left iliac artery was occluded, and a left iliac endarterectomy and thrombectomy were performed immediately. RESULTS: A significant occlusive plaque was separated distally and transected in a smooth fashion, and fresh thrombus was also removed. The procedure was successfully accomplished without any further complication with excellent restoration of arterial blood flow to the left lower extremity. Doppler study showed good triphasic flow in the iliac artery and all its branches. Because of the arterial repair, the posterior portion of the surgery was not undertaken at that time and was performed 2 weeks later. CONCLUSIONS: Early recognition and appropriate treatment can prevent serious sequelae. Great care and observation should be given to the patients before surgery, intraoperatively, as well as after surgery.

Arterial Occlusive Diseases↗
PubMed2003

Thinning of the anterior capsule associated with congenital aniridia.

PURPOSE: To report the unusual finding of intraoperative fragility of the anterior capsule in some patients with congenital aniridia and determine the histopathologic etiology of this finding. SETTING: Cincinnati Eye Institute, Cincinnati, Ohio, USA. METHODS: Anterior lens capsule specimens were obtained from aniridic and nonaniridic patients during cataract surgery. The intraoperative behavior of each capsule was noted, after which the specimens were submitted for histopathologic evaluation. RESULTS: All anterior capsule specimens from the nonaniridic patients were of normal thickness. Some, but not all, anterior capsule specimens from the aniridic patients were remarkably thin. Thin capsules were associated with extreme intraoperative fragility. CONCLUSIONS: Greater awareness of anterior capsule fragility in some aniridic patients may reduce the risk of capsule complications and lead to safer surgical outcomes.

Adult↗
PubMed2003

Closed-loop control of propofol anaesthesia using bispectral index: performance assessment in patients receiving computer-controlled propofol and manually controlled remifentanil infusions for minor surgery.

BACKGROUND: In a previous study we used the bispectral index (BIS) for automatic control of propofol anaesthesia, using a proportional-integral-differential control algorithm. As control was less than optimal in some patients, we revised the constants of the control algorithm. The aim of the current study was to measure the performance of the revised system in patients undergoing minor surgery under propofol and remifentanil anaesthesia. METHODS: Twenty adult patients scheduled for body surface surgery were enrolled. Anaesthesia was manually induced with target-controlled infusions (TCI) of propofol and remifentanil. After the start of surgery, when anaesthesia was clinically adequate, automatic control of the propofol TCI was commenced using the revised closed-loop system. For patients 11-20, effect-site steering was also incorporated into the closed-loop control algorithm. Adequacy of anaesthesia during closed-loop control was assessed clinically, and by calculating the median performance error (MDPE), the median absolute performance error (MDAPE) and the mean offset of the control variable. RESULTS: The system provided adequate operating conditions and stable cardiovascular values in all patients during closed-loop control. The mean MDPE and MDAPE were -0.42% and 5.63%, respectively. Mean offset of the BIS from setpoint was -0.2. No patients reported awareness or recall of intraoperative events. CONCLUSIONS: The system was able to provide clinically adequate anaesthesia in all patients, with better accuracy of control than in the previous study. There was a tendency for more accurate control in those patients in whom the control algorithm incorporated effect-site steering.

Adult↗
PubMed2002

Closed-loop control of anesthesia using Bispectral index: performance assessment in patients undergoing major orthopedic surgery under combined general and regional anesthesia.

BACKGROUND: The Bispectral Index (BIS) is an electroencephalogram-derived measure of anesthetic depth. A closed-loop anesthesia system was built using BIS as the control variable, a proportional-integral-differential control algorithm, and a propofol target-controlled infusion system as the control actuator. Closed-loop performance was assessed in 10 adult patients. METHODS: Ten adult patients scheduled to undergo elective hip or knee surgery were enrolled. An epidural cannula was inserted, and 0.5% bupivacaine was used to provide anesthesia to T8 before general anesthesia was induced using the propofol target-controlled infusion system under manual control. After the start of surgery, when anesthesia was clinically adequate, automatic control of anesthesia was commenced using the BIS as the control variable. Adequacy of anesthesia during closed-loop control was assessed clinically and by calculating the median performance error, the median absolute performance error, and the mean offset of the control variable. RESULTS: The median performance error and the median absolute performance error were 2.2 and 8.0%, respectively. Mean offset of the BIS from the set point was 0.9. Cardiovascular parameters were stable during closed-loop control. Operating conditions were adequate in all patients but one, who began moving after 45 min of stable anesthesia. No patients reported awareness or recall of intraoperative events. In three patients, there was oscillation of the measured BIS around the set point. CONCLUSIONS: The system was able to provide clinically adequate anesthesia in 9 of 10 patients. Further studies are required to determine whether control performance can be improved by alterations to the gain factors or by using an effect site-targeted, target-controlled infusion propofol system.

Adult↗
PubMedDate not supplied

Anesthesia awareness.

Explore the source record for details and available documents.

Anesthesia, General↗
PubMed2000

Awareness due to disconnection from the fresh gas supply: why could ventilation be achieved in spite of disconnection from the fresh gas supply?

An anaesthesia ventilator of to-and-fro type incorporated into the anesthesia machine was used for mechanical ventilation in a patient undergoing plastic surgery under sevoflurane anaesthesia. During operation, elevation of blood pressure and tachycardia, which suggested inadequate anesthesia could not be managed by adjustment of sevoflurane to higher concentrations. However, the patient's lungs could be well ventilated without problems. Close to the end of anaesthesia, a disconnection at the mixed gas common outlet before the check valve of anaesthesia machine was detected. The patient could recall and recount all the happening during the operation signifying that he was not sufficiently anesthetized. In the case that the fresh gas supply line before the check valve is disconnected, the lungs can still be ventilated if a to-and-fro type of ventilator is used. Because there is no leakage of gas from the check valve every bit of the gas which drives the ventilator begins to work and deliver a flow of gas sufficiently to maintain a tidal volume. As a result, anaesthetic gas is replaced by a driving gas. A ventilator of to-and-fro type is still used in clinical anesthesia due to its simple design. The phenomenon reflects the pitfall in the design of a to-and-fro type anaesthesia ventilator.

Adult↗