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At least 883 records · Page 49Linked to original sources

PubMed1991

Intraoperative facial nerve monitoring: prognostic aspects during acoustic tumor removal.

Intraoperative facial nerve monitoring with electrical stimulation (IFNMES) has become an integral part of acoustic tumor surgery. We reviewed the records of fifty-six patients who underwent translabyrinthine acoustic tumor removal with IFNMES. There was excellent correlation between intraoperative facial nerve activity and immediate postoperative facial nerve function (24 hours after surgery and at hospital discharge). Our data would suggest that patients who exhibit less than 500 microvolts of ongoing EMG activity during surgery, and who yield at least a 500-microvolt contraction when stimulated with 0.05 milliamps at the brainstem after tumor removal, can expect an excellent immediate facial nerve result (grade I or II).

Ear Neoplasms↗

PubMed1993

[CT guided transsphenoidal surgery: report of nine cases].

We have developed a Computed Tomography system for use in the operating room and applied this CT system to intraoperative monitoring during transsphenoidal surgery. This system includes Toshiba TCT-300 CT system, mobile CT scanner gantry, digitally controlled operating table and head fixation system. Between June 1989 and Dec. 1989, CT guided transsphenoidal surgery was carried out in 9 cases in our department. The suprasellar masses were visualized directly during transphenoidal surgery and were removed safely and efficiently. Under this CT monitoring system the surgeon can obtain accurate information about the location and volume of residual tumor as well as about the important surrounding deeper structure. Another advantage of this system is that the digitally controlled operating table makes it possible to keep the patient in a head-up position, which lessens oozing from the parasellar region during transsphenoidal surgery. We believe the best application of this method is that for pituitary tumor with moderate suprasellar extension. Nine cases were reported in this paper which were operated on using this system. To our knowledge, this is the first report of use of intraoperative CT monitoring during transsphenoidal surgery.

Adenoma↗

PubMed1995

[Implantable automatic cardioverter-defibrillator: anesthesia experience].

To evaluate the anesthetic management and intraoperative events in patients benefiting from an automatic implantable cardioverter defibrillator. We retrospectively reviewed the charts of 12 male patients in whom we had placed automatic implantable defibrillators (AID). In particular we assessed anesthetic management, recording type of anesthetic and intraoperative monitoring, the technique used to implant the AID and complications during and after surgery. Arterial pressure and heart rate were also analyzed. All patients experienced tachyarrhythmia or ventricular fibrillation. Ten of the 12 patients presented left ventricular ejection fractions (LVEF) between 21 and 28%; LVEF in the other 2 patients exceeded 30% (45 and 62%). All experienced statistically significant decreases in arterial pressure coincident with fibrillation. Three patients required dobutamine for sustained hypotension. Six presented ventricular extrasystoles during surgery. Late complications included 1 sudden death after surgery and 1 infection which obliged removal of the AID. AID implantation is not risk-free, given that the patients involved have heart disease with considerable degrees of deterioration in myocardial function. Nevertheless, with extensive preoperative examination of the patient and proper anesthetic management, complications before and after surgery are rare.

Adult↗

PubMed1992

Evaluation of transesophageal atrial pacing stethoscope in adult surgical patients under general anesthesia.

Sinus bradycardia (SB) and atrioventricular junctional rhythm (AVJR) commonly cause circulatory insufficiency in anesthetized surgical patients. Treatment is usually with drugs, which can be ineffective or have adverse effects. Cardiac pacing might be preferred, but the transvenous or epicardial routes are too invasive for routine use, and transcutaneous pacing fails to preserve atrial transport function. Transesophageal atrial pacing (TAP) lacks these disadvantages, yet unavailability of inexpensive products has prevented more widespread use. Therefore, a pacing esophageal stethoscope (PES) fabricated by addition of bipolar electrodes to disposable esophageal stethoscopes routinely used for intraoperative monitoring, was evaluated in 100 anesthetized adults. TAP thresholds (10-msec pulses) and hemodynamic effects of TAP as treatment for incidental SB (< or = 60 beats/min) or AVJR were determined. Minimum TAP thresholds (mean +/- standard error) in 48 males were 7.3 +/- 0.3 mA and in 51 females were 8.5 +/- 0.4 mA. Corresponding inferior alveolar ridge-to-electrode distances were 32.5 +/- 0.2 and 30.4 +/- 0.2 cm. For 48 patients with SB < or = 60 beats/min (54 +/- 1 beats/min), TAP (81 +/- 1 ppm) produced average 15, 11, and 14 mmHg increases in systolic, diastolic, and mean arterial pressure, respectively (P < 0.001). For 11 patients with AVJR (71 +/- 5 beats/min), TAP (92 +/- 3 ppm) produced average 23 and 15 mmHg increases in systolic and mean arterial pressure, respectively (P < 0.05). There were no apparent complications of TAP. TAP with a PES appears practical, safe, and effective for prophylaxis and treatment of SB or AVJR in anesthetized surgical patients.

Adult↗

PubMed1993

Mechanisms of incomplete cardioplegia distribution during coronary artery surgery. An intraoperative transesophageal contrast echocardiography study.

BACKGROUND: Cardioplegia is used to protect the myocardium from ischemic injury during open-heart surgery. However, the delivery of cardioplegic solutions may be impaired by anatomic and/or functional conditions, such as the development of transient aortic regurgitation during antegrade administration of cardioplegia or shunting through a foramen ovale during retrograde administration. In this study, the authors used a new method of cardioplegia administration, based on intraoperative contrast echocardiography, to detect on-line causes of inadequate cardioplegia delivery. METHODS: Forty patients with coronary artery disease and a competent aortic valve, who were treated consecutively, were enrolled in this study. Patients were monitored intraoperatively by transesophageal contrast echocardiography during cardioplegia delivery. Antegrade cardioplegia was administered into the aortic root following aortic occlusion in all patients. Twenty-two patients also received retrograde cardioplegia, administered through the right atrium. The echo-contrast agent consisted of a stable suspension of 5% human albumin microbubbles with a concentration of 4 x 10(8) microbubbles/ml and a diameter of 4 +/- 1 mu. RESULTS: Antegrade cardioplegia was not associated with aortic regurgitation in 23 of 40 (58%) patients. Seven patients (17%) had only mild aortic regurgitation, four patients (10%) had moderate regurgitation, and six (15%) had severe aortic regurgitation. The percent of myocardial opacification was 76.0 +/- 10.5 in the 23 patients who did not have aortic regurgitation, 76.0 +/- 17.0 in the 7 patients who had mild regurgitation, 52.5 +/- 18.1 in the 4 patients who had moderate regurgitation, and 48.5 +/- 18.3 in 6 patients who had severe aortic regurgitation (Kruskal-Wallis stat, 12.9; P < 0.005). Retrograde cardioplegia was not associated with right-to-left shunt in 11 of 22 patients (50%). In seven patients (32%), there was only a mild passage of contrast material to the left atrium. In the remaining four patients (18%), there was a moderate (one patient) to severe (three patients) right-to-left shunt at the level of the fossa ovalis. CONCLUSIONS: This study shows that incomplete myocardial distribution of cardioplegia, secondary to transient aortic valve incompetence or shunting through the foramen ovale, is not uncommon in patients undergoing coronary surgery.

Cardioplegic Solutions↗

PubMed1994

Use of monitoring devices during anesthesia for cardiac surgery: a survey of practices at public hospitals within the United Kingdom and Ireland.

A questionnaire was sent to all 42 public hospitals, within the United Kingdom (UK) and Ireland, known to conduct elective cardiac surgery. Information was sought with regard to the availability of intraoperative monitoring equipment. A one hundred percent response rate was achieved. Pulse oximetry, inspired oxygen analysis, and expired carbon dioxide analysis were not utilized at 4, 8, and 10 hospitals, respectively. Similarly, continuous monitoring of arterial oxygen tension and oxygen fraction in the gas flow to the bypass machine was not conducted in 28 and 32 hospitals, respectively. This survey revealed that essential anesthetic monitoring devices, as defined by the United Kingdom Association of Anesthetists, are not in routine usage during the pre-bypass and post-bypass phases of anesthesia for cardiac surgery within the British Isles.

Adult↗

PubMed1997

Intraoperative color duplex sonography of basal arteries during aneurysm surgery.

This prospective study aimed at (1) characterizing the duplex sonographic appearance of cerebral aneurysms, (2) visualizing their location, and (3) ensuring the complete occlusion of the aneurysm as well as the patency of the basal arteries during aneurysm surgery. During 9 months 30 craniotomies for aneurysm clipping in 29 patients were monitored intraoperatively by B-mode and color-coded duplex sonography. Following craniotomy the aneurysm and the preaneurysmatic and postaneurysmatic arteries were sonographically visualized before and after clipping and removal of the spatulas. Twenty-seven (90%) of 30 aneurysms appeared as a hypoechoic structure. Together with the typical dichromatic picture in the color mode and the characteristic bidirectional flow pattern in the duplex mode, 29 (97%) of 30 aneurysms were identified and localized anatomically correctly. Eighty (99%) of 81 relevant vessels were visualized and measured with the Doppler mode. After clipping, flow was detectable in all major arteries except 3 middle cerebral artery (MCA) branches. In 1, occlusion was confirmed by postoperative angiography. In the other 2, early postoperative computed tomography showed an infarction of the corresponding MCA territories. This study demonstrated the potential of color duplex sonography to visualize and characterize cerebral aneurysms and adjacent basal arteries before and after clipping. It offers a noninvasive intraoperative method to control the patency of basal arteries and complete occlusion of the aneurysm.

Aneurysm↗

PubMed2002

Strategies for surgical management of cerebral aneurysms of special location, size and form--approach, technique and monitoring.

Special strategies are mandatory for optimal surgical management of aneurysms of special location, size and form. Approaches of extradural selective anterior clinoidectomy, partial occipital condylectomy, transpetrosal approach by anterior petrosectomy and supracerebellar transtentorial approach are discussed among them. Furthermore various types of temporary and permanent clipping procedures are discussed along with mention of intraoperative monitoring.

Craniotomy↗

PubMed1988

Cochlear nerve monitoring during cerebellopontine angle operations.

The authors present their experience with intraoperative monitoring of cochlear nerve action potentials (AP) in 30 adult patients. Operative procedures were acoustic neuroma excision with attempted hearing preservation and selective vestibular neurectomy in patients with incapacitating Meniere's disease and serviceable hearing (SRT less than 50 db, discrimination greater than 60%). Loss of AP is detected rapidly and has been demonstrated after manipulation of the cochlear nerve and after coagulation of small arteries on the tumour capsule. Presence of an AP at the end of the procedure usually correlates with postoperative preservation of hearing. AP monitoring appears to be a reliable means of detecting potentially reversible changes in cochlear nerve function intraoperatively.

Action Potentials↗

PubMed1995

Cerebral oxygenation during pediatric cardiac surgery using deep hypothermic circulatory arrest.

BACKGROUND: Deep hypothermic circulatory arrest is a widely used technique in pediatric cardiac surgery that carries a risk of neurologic injury. Previous work in neonates identified distinct changes in cerebral oxygenation during surgery. This study sought to determine whether the intraoperative changes in cerebral oxygenation vary between neonates, infants, and children and whether the oxygenation changes are associated with postoperative cerebral dysfunction. METHODS: The study included eight neonates, ten infants, and eight children without preexisting neurologic disease. Cerebrovascular hemoglobin oxygen saturation (SCO2), an index of brain oxygenation, was monitored intraoperatively by near-infrared spectroscopy. Body temperature was reduced to 15 degrees C during cardiopulmonary bypass (CPB) before commencing circulatory arrest. Postoperative neurologic status was judged as normal or abnormal (seizures, stroke, coma). RESULTS: Relative to preoperative levels, the age groups experienced similar changes in SCO2 during surgery: SCO2 increased 30 +/- 4% during deep hypothermic CPB, it decreased 62 +/- 5% by the end of arrest, and it increased 20 +/- 5% during CPB recirculation (all P < 0.001); after rewarming and removal of CPB, SCO2 returned to preoperative levels. During arrest, the half-life of SCO2 was 9 +/- 1 min in neonates, 6 +/- 1 min in infants, and 4 +/- 1 min in children (P < 0.001). Postoperative neurologic status was abnormal in three (12%) patients. The SCO2 increase during deep hypothermic CPB was less in these patients than in the remaining study population (3 +/- 2% versus 33 +/- 4%, P < 0.001). There were no other significant SCO2 differences between outcome groups. CONCLUSIONS: Brain oxygenation changed at distinct points during surgery in all ages, reflecting fundamental cerebral responses to hypothermic CPB, ischemia, and reperfusion. However, the changes in SCO2 half-life with age reflect developmental differences in the rate of cerebral oxygen utilization during arrest, consistent with experimental work in animals. Certain intraoperative cerebral oxygenation patterns may be associated with postoperative cerebral dysfunction and require further study.

Aging↗

PubMed1994

Intraoperative evoked potential monitoring in acetabular surgery.

The effectiveness of intraoperative sciatic nerve monitoring was evaluated for 88 consecutive patients undergoing open reduction and internal fixation for acetabular fractures. Intervention outcomes and pre and postoperative electrophysiologic status were compared to postoperative functional findings. Only 2% of the patients demonstrated iatrogenic sciatic nerve palsies. Functional and evoked potential findings were in agreement for 89% of the patients with postoperative palsies, while 26% of the functionally normal patients showed abnormal evoked potentials. Intervention occurred in 55 surgeries; 80% of interventions involved the peroneal nerve. Forty one of the 55 patients who had interventions based on evoked potential results showed recovery of responses to baseline. Of the 14 patients with incomplete intervention recovery, 11 showed impaired postoperative responses. Patients with preoperative evoked potential abnormalities did not show increased susceptibility to iatrogenic evoked potential changes.

Acetabulum↗

PubMed1998

Intraoperative facial nerve monitoring (IFNM) predicts facial nerve outcome after resection of vestibular schwannoma.

Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB degree I and degree II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 microV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB degree III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB degree IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 microV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB degree IV, respectively. Two patients with initial mHB degree IV improved to mHB degree III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.

Adult↗

PubMed1991

Measurement of drill-generated noise levels during ear surgery.

The results of intraoperative monitoring of the electrocochleogram in patients undergoing surgery for poorly controlled Menières Disease are presented with particular reference to the masking effect of drill-generated noise. The results obtained using a direct, in vivo, electrophysiological method of assessment of drill-generated noise levels are compared with previous postmortem and intraoperative studies and the implications with respect to the likelihood of drill-generated noise induced acoustic trauma are discussed.

Audiometry, Evoked Response↗

PubMed1995

Transcranial magnetic motor-evoked potentials in scoliosis surgery.

Spinal cord monitoring using SSEPs is an accepted adjunct in the surgical correction of spinal deformities, but does not directly assess motor function. Motor-evoked potentials have been introduced in an effort to meet this important need. In this series of 18 patients, the feasibility of intraoperative monitoring using transcranial magnetic motor-evoked potentials is documented. The potential value of this neurophysiologic monitoring technique, as well as the pitfalls in interpretation, are reviewed.

Adolescent↗

PubMed2003

[The use of neuromuscular monitoring in Germany].

AIM: As there are no reliable epidemiological data for the use of muscle relaxants in Germany,we conducted a mailing study. The aim of the study was to compare the use of muscle relaxants between German anaesthesia departments. In the present part of the presentation we focused on neuromuscular monitoring (NMM) and management of residual paralysis. METHODS: A total number of 2,996 questionnaires were sent to all registered anaesthesiological facilities in Germany and the return was 68.6% (2054 questionnaires). RESULTS: In 574 of the returned questionnaires (28%) the regular use of NMM was confirmed. Intraoperative monitoring of neuromuscular block and assessment of neuromuscular recovery were the most frequent applications of NMM, i.e. 25% and 18% of returned questionnaires, respectively. Clinical signs, however, are still the most popular way to estimate the degree of neuromuscular blockade. Moreover, routine reversal at the end of surgery with a neostigmin/atropine mixture was not practiced in 75% of the anaesthesia departments. CONCLUSIONS: This survey revealed that NMM is still very rarely used in daily clinical practice. Especially the seldom use of NMM to assess residual paralysis has to be improved.

Anesthesiology↗

PubMed2000

Patterns of palmar skin temperature alterations during transthoracic endoscopic T2 sympathectomy for palmar hyperhidrosis.

Transthoracic endoscopic T2 sympathectomy has been widely applied to the treatment of a variety of sympathetically mediated disorders. Palmar hyperhidrosis is probably the most common indication for thoracic sympathectomy, especially in certain subtropical areas. Which sympathetic ganglion is to be ablated and how extensive such ablation is enough to eliminate palm sweating are two important issues. Intraoperative monitoring of palmar skin temperature (PST) is the most frequently used method for assessing the accuracy as well as adequacy of ablation of the target sympathetic ganglia. With continuous monitoring of bilateral PST during the operative course of T2 sympathectomy, it was possible to depict the alterations of bilateral PST in response to specific surgical procedures in a real-time manner. For each case, a PST graph was obtained, which represented the graphical expression of intraoperatively recorded bilateral PST data plotted against time. The PST graphs of 93 consecutive cases were analysed. Three types of PST graphs existed, reflecting different responses of bilateral PST to different surgical procedures during the operation. In Type I PST graph pattern, found in 58 cases, skin incision and intercostal muscle dissection caused dramatic bilateral PST drop; and unilateral T2 sympathectomy induced synchronous bilateral PST elevation. Twenty-four cases demonstrated Type II PST graph pattern, in which unilateral T2 sympathectomy caused only ipsilateral PST elevation, although the PST-depressing effect of skin incision and muscle dissection was as significant as in Type I graph pattern. In the 11 cases who showed Type III PST graph pattern, neither skin incision nor T2 sympathectomy induced any apparent changes of PST on either side, giving rise to two rather flat PST curves on the PST graphs. These findings implicate that reciprocal interactions between bilateral sympathetic activities exist in the majority of cases, and that crossover sympathetic modulation may play a role in the neural control of the sudomotor and vasomotor activities of the palms. This study also provides information regarding how PST would possibly change following specific surgical procedures during transthoracic endoscopic T2 sympathectomy, which may be of importance to those who use intraoperative PST monitoring as a guide in determining whether or not the correct sympathetic ganglia are ablated for adequate sympathetic denervation of the palms.

Adolescent↗

PubMed1999

Intraoperative facial nerve monitoring: a comparison between electromyography and mechanical-pressure monitoring techniques.

OBJECTIVES: To examine the hypothesis that for intraoperative facial nerve monitoring, an EMG monitor is more sensitive than a mechanical-pressure monitor. To compare the threshold sensitivity of the two facial nerve monitoring methods-mechanical-pressure versus EMG--by using them simultaneously during surgery. To assess and compare their true- and false-positive responses in otologic and neurotologic procedures. SETTING: A tertiary referral private otology/neurotology practice. STUDY DESIGN: Prospective case-controlled study. PATIENTS AND METHODS: The facial nerve of 46 consecutive patients undergoing various otologic and neurotologic procedures was stimulated intraoperatively using a pulsed constant-current. Facial responses were monitored using the Silverstein WR-S8 Monitor/Stimulator and the Brackmann EMG System simultaneously. The threshold (i.e., minimal) current level required to elicit a response from each monitor was recorded. Monitor responses to facial nerve manipulation (including false-positive responses) were assessed by continuous recording of all responses, using the Wiegand Monitoring System, and noting the causative event for each response. RESULTS: The EMG monitor responded to lower current threshold (p < 0.001) in every surgical procedure and for every nerve segment studied. However, the average threshold difference was <0.05 mAmps and in clinical practice, when using above threshold stimulation, becomes negligible. In posterior fossa surgery, the EMG monitor showed higher sensitivity by responding earlier to various manipulations of the bare facial nerve. The EMG had more false-positive responses than the mechanical-pressure monitor. CONCLUSIONS: In otologic surgery, if monitoring is required, the mechanical-pressure monitor is used. In neurotologic surgery, both monitors are used simultaneously.

Adolescent↗

PubMed2001

Mapping the VIIIth cranial nerve by electrical stimulation: methods for differentiating auditory from vestibular responses.

HYPOTHESIS: The goal of this study was to map the VIIIth cranial nerve by electrical stimulation. Specifically, the authors sought to 1) characterize auditory and vestibular evoked responses elicited by electrical stimuli delivered directly to the exposed surface of the VIIIth cranial nerve and 2) compare electrically evoked responses elicited in brainstem nuclei with extracranially recorded far-field potentials. BACKGROUND: Intraoperative monitoring of auditory brainstem responses is useful during cerebellopontine angle surgery. Identification of the vestibular portion of the VIIIth cranial nerve, which traditionally has been performed by physical characteristics and some electrophysiologic properties, is important because the vestibular subdivision in humans is indistinct in approximately 25% of cases. Positive identification of evoked responses emanating from the vestibular nerve would constitute a marked improvement over existing intraoperative techniques that use acoustic stimuli only. METHODS: Experiments were performed on 12 anesthetized cats. Electrical pulse stimuli were delivered using a bipolar electrode placed directly on the surface of the exposed VIIIth cranial nerve at several sites. Computer-averaged evoked responses were recorded from far-field electrodes placed on the scalp and from near-field electrodes stereotaxically positioned in or near the inferior colliculus and abducens nucleus. RESULTS: Latencies and morphologies of waves recorded in brainstem nuclei were compared with those of waves recorded extracranially. Direct electrical stimulation of the cochlear nerve elicited a four-wave, auditory brainstem response-like extracranial response, strong activity in the inferior colliculus, and weak activity in the abducens nucleus. Direct stimulation of the vestibular nerve produced a two-wave extracranial response, weak inferior colliculus activity, and strong abducens activation. Stimulation at the border of the cochlear and vestibular nerves produced intermediate responses that possessed both cochlear and vestibular characteristics. CONCLUSION: Direct electrical stimulation of the cochlear and vestibular subdivisions elicits evoked responses with distinctly different wave morphologies. Obtaining electrically evoked responses intraoperatively is feasible and may be of substantial value in the unambiguous identification of VIIIth cranial nerve subdivisions.

Animals↗