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Results for “Monitoring, Intraoperative”

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At least 397 records · Page 22Linked to original sources

PubMed1995

Elective intraoperative intracranial pressure monitoring during laparoscopic cholecystectomy.

The effects of artificial pneumoperitoneum on intracranial pressure have not been clearly defined. Initial animal studies indicate that elevated intra-abdominal pressure might have a deleterious effect on intracranial pressure. We report a case in which intracranial pressure was monitored intraoperatively during laparoscopic cholecystectomy. Intracranial pressure increased abruptly when the peritoneal cavity was insufflated, with the operating table in the Trendelenburg position, and decreased slightly with elevation of the head of the operating table. Initial opening intracranial pressure values were re-established on desufflation of the abdomen. Intracranial pressure monitoring should be considered when planning a laparoscopic procedure on patients with the potential for decreased intracranial compliance.

Adult↗

PubMedDate not supplied

Feasibility of intraoperative corneal topography monitoring during photorefractive keratectomy.

PURPOSE: We propose a feasibility study of new corneal topography technology with the aim of monitoring intraoperative corneal topography during excimer laser photorefractive keratectomy. The PAR system measures corneal topography with single grid projection and triangulation but requires fluorescent fluid to be deposited on the corneal surface for shape extraction. We propose and demonstrate a novel corneal topography system based on structured incoherent visible light projection and triangulation that does not require addition of fluorescent fluid. METHODS: We used a binary liquid crystal spatial light modulator to display multiple fringe patterns onto the cornea. The depth accuracy of the corneal topography system was measured using a white reflected test sphere mounted on a micrometer translation stage. The performance of the corneal topography system was tested on 5 de-epithelialized swine eyes in vitro ablated with a VISX excimer laser. RESULTS: Depth accuracy on the test sphere was 0.5+/-0.75 microm over an area of 17.6 mm2. On de-epithelialized swine corneas, ablation at the apex of the cornea treated with an excimer laser was measured without addition of fluorescein. CONCLUSIONS: This new corneal topography system achieved an adequate level of accuracy on a test sphere.

Animals↗

PubMedDate not supplied

Bilobed splitting of median nerve somatosensory evoked p14 potential under deep hypothermia.

OBJECTIVE: To further elucidate temperature related changes in subcortical components of somatosensory evoked potentials (SEP) in intraoperative monitoring. METHODS: Intraoperative monitoring of subcortical median nerve SEP under deep hypothermia is described in a patient undergoing intracranial giant aneurysm surgery. The P14 potential was recorded from Fz-Pgz (front to nasopharynx). RESULTS: At a body core temperature of less than 17 degrees C, P14 showed a bilobed splitting that was reversible with rewarming. A comparison with latencies of other subcortical potentials of presynaptic and postsynaptic origin, recorded at the neck, speaks in favor of a presynaptic generation of the first P14 wave and a postsynaptic origin of the latter P14 wave. CONCLUSIONS: Deep hypothermia may separate presynaptic and postsynaptic electric activity of evoked potentials that overlap at normal body temperature. Such possible phenomena must be kept in mind to correctly interprete monitoring data at very low body temperatures and may help in better understanding the generation of different SEP components.

Adult↗

PubMed2005

Palsies of the fifth cervical nerve root after cervical decompression: prevention using continuous intraoperative electromyography monitoring.

OBJECT: A desire to prevent complications resulting from spinal surgery led to the development of intraoperative monitoring. Intraoperative electromyography (EMG) provides useful diagnostic information regarding nerve root function during spinal and peripheral nerve surgeries. The C-5 nerve root is considered particularly vulnerable to injury during cervical surgery. Despite advances in techniques, the incidence of postoperative C-5 palsy has not changed. METHODS: The authors reviewed prospectively collected data obtained in 161 patients who underwent 171 cervical procedures. In 116 procedures, operative monitoring was modified to include continuous C-5 EMG from the deltoid muscle. In cases in which spontaneous C-5 activity occurred, an appropriate change in operative manipulation was made. A historical control group consisted of a retrospective review of 55 procedures that were monitored using conventional techniques. In the retrospective cohort, four (7.3%) of 55 patients presented after undergoing surgery for C-5 nerve root palsy. In each patient conventional monitoring revealed unremarkable findings. In the prospective cohort, intraoperative spontaneous EMG activity necessitated a change in either positioning or operative technique in three cases. Only one patient (0.9%) experienced postoperative C-5 palsy. Postoperative C-5 palsy occurred in no patient in whom there was no intra-operative evidence of root irritation (p < 0.03, chi-square test). CONCLUSIONS: The incidence of postoperative C-5 palsies was reduced from 7.3% to 0.9% due to intraoperative continuous EMG monitoring. No patient suffered a postoperative C-5 palsy when intraoperative evidence of root irritation was absent.

Case-Control Studies↗

PubMed2006

Flow reduction in high-flow arteriovenous access using intraoperative flow monitoring.

PURPOSE: This study used intraoperative monitoring of the access flow to evaluate the results of flow reduction in the management of high-flow arteriovenous access-related symptoms of distal ischemia and cardiac insufficiency. METHODS: A retrospective study was conducted of 95 patients (78 with ischemia, 17 with cardiac failure) who underwent flow reduction between 1999 and 2005. A preoperatively measured access flow-volume rate > 800 mL/min for autogenous accesses (n = 77) and > 1200 mL/min for prosthetic accesses (n = 18) was the selection criterion for the use of a flow reduction procedure. Flow reduction was achieved using a spindle-like narrowing suture near the anastomosis and final placement of a polytetrafluoroethylene strip while a flow meter was used for intraoperatively measuring the access flow. The desired postoperative flow was 400 mL/min for autogenous and 600 mL/min for prosthetic accesses. RESULTS: The mean preoperative access flow was 1469 +/- 633 mL/min in patients with ischemia and 2084 +/- 463 mL/min in patients with cardiac failure, without significant differences between access types. The flow was reduced to 499 +/- 175 mL/min for autogenous accesses and to 676 +/- 47 mL/min for prosthetic accesses. The mean follow-up was 25 months (range, 1 to 73 months). Complete long-term relief of symptoms was observed in 86% of patients with ischemia and in 96% of patients with cardiac failure. Reconstruction significantly increased the digital-brachial index (0.41 +/- 0.12 vs 0.74 +/- 0.11; P < .05) and mean distal arterial pressure (47 +/- 17 mm Hg vs 79 +/- 21 mm Hg; P < .05) in patients with ischemia. Primary patency rates were significantly better for reconstructed autogenous accesses compared with rates of prosthetic accesses (91% +/- 4% vs 58% +/- 12% at 12 months; 81% +/- 6% vs 41% +/- 14% at 36 months; P < .001). The low patency of reconstructed prosthetic accesses is due to the high thrombosis risk of accesses that have a flow < 700 mL/min. CONCLUSIONS: Flow reduction using intraoperative access flow monitoring is an effective and durable technique allowing for the correction of distal ischemia and cardiac insufficiency in patients with a high-flow autogenous access. The desired postoperative access flow of 400 mL/min is not associated with an increased risk of thrombosis. Flow reduction of prosthetic access is as effective; however, a higher access flow than the desired 600 mL/min seems to be necessary to achieve an acceptable patency in prosthetic accesses.

Arteries↗

PubMed1996

Iatrogenic facial nerve injury: the role of facial nerve monitoring.

Intraoperative facial nerve monitoring has emerged as a powerful tool for facilitation of surgery involving the facial nerve. This tool must be properly applied and maintained, however, in order to avoid untoward results and to maximize its potential benefits. Facial nerve monitoring is best suited for prevention of iatrogenic injury. Once injury has become established, its value may be severely limited, especially for moderate to severe injury, in which visual assessment of injury is still the most effective means to determine the need for repair. The most valuable derivative of facial nerve monitoring is enhanced awareness of the edge of the facial nerve contour. This allows strategic alterations in surgical technique for improved facial nerve functional preservation. Although facial nerve monitoring appears to have already had a favorable influence on facial nerve preservation, further improvement seems likely over time through an ongoing process of trial and error.

Ear Diseases↗

PubMed2000

A new cortical electrode for neuronavigation-guided intraoperative neurophysiological monitoring: technical note.

Intraoperative neurophysiological mapping and monitoring of eloquent brain areas can be combined with image-guided localisation to enhance the safety and efficacy of surgical procedures in the motor cortex. We designed a new type of cortical electrode which can be repeatedly placed on the cortical surface and allows accurate and reproducible stimulation by means of a navigation pointer. The newly designed device consists of a monopolar electrode contact for direct cortical stimulation, housed in a holder which allows placement, easy removal, and precise repeated placement of a surgical navigation pointer. It can be used for navigation-guided, high-frequency anodal monopolar cortical stimulation (MCS) for the mapping of eloquent cortex, and for monitoring of motor pathways. While the cortex is stimulated, compound muscle action potentials (CMAP) are recorded from muscles of the contralateral extremities and are assessed both qualitatively and quantitatively. When the device is used in combination with intraoperative navigation, the stimulation sites may optionally be registered or displayed on the system monitor. This allows repeated pinpointing and obviates the need for strip or grid electrodes in the operative field; although such electrodes may be useful for continuous monitoring, they often are in the surgeon's way. In addition, the primary and supplementary motor cortex can be mapped by determining the location of the sites of stimulation on surface-projected images of the cerebral cortex.

Brain Mapping↗

PubMed1998

[Automatic artefact detection in intraoperative EEG monitoring].

The quality of intraoperative EEG monitoring is decisively influenced by automatic detection of artefacts. Undetected artefacts can mimic non-existing trends thus leading to misinterpretations of the EEG. Methods of computer-assisted artefact detection are developed and described: On the one hand the algorithms include simple threshold values of atypical parameters, on the other, they rely on situation-dependent smoothing of the EEG signal. Too strong a deviation of an artefact-relevant parameter from its smoothed value results in exclusion of the EEG segment (epoch) from further computation trends. The algorithms can clearly reduce the misclassification of highly artefact-contaminated epochs in the awake patient, without allowing anaesthesia-relevant changes to escape notice.

Algorithms↗

PubMed1991

[Threefold intraoperative electrophysiological monitoring of vestibular neurectomy].

A threefold intraoperative monitoring of facial nerve, auditory nerve and vestibular nerve function was performed in 14 cases of retrosigmoidal neurectomy. The facial nerve was monitoring with a pressure transducer placed against the cheek (Opalarm system). The auditory nerve was monitored with acoustically (click) evoked early potentials and the vestibular nerve was monitored with electrically evoked vestibular potentials obtained by direct stimulation (biphasic current pulses of 0.75-mA p-p, 100 us, 20/s) of the exposed vestibular nerve in the cerebellopontine angle before, during and after neurectomy. A characteristic vertex negative peak having a latency of approximately 2 ms and approximately 0.5 uV amplitude was obtained between a forehead and an ipsilateral ear lobe electrode (2 x 1,000 averaged responses over 10 ms) before the neurectomy. This response disappeared after selective vestibular nerve section proximal to the stimulation site. A diminished response amplitude was measured after incomplete nerve section. Simultaneous acoustic masking had no influence on the vestibular potential. The 14 operated patients became all free of vertiginous spells and drop-attacks except one patient who developed a contralateral Menière's. Facial nerve function remained normal in all. Hearing preservation was obtained in 12 patients (86%). The threefold intraoperative monitoring has turned out to be an additional safety factor for facial and auditory nerve preservation and, thanks to the recording of vestibular potentials, it increased the efficiency of vestibular neurectomy.

Adult↗

PubMed2003

Reliable and convenient method for the fixation of recording electrodes on nonshaved scalp for intraoperative electrophysiological monitoring: technical note.

BACKGROUND: Difficulties with the intraoperative monitoring of evoked responses sometimes occur because of displacement or dislodgment of the recording electrodes during surgery, especially if placed on nonshaved scalp. METHODS: An alternative fixation method of the recording electrode on the nonshaved scalp was developed. The sterile subdermal needle electrode was attached on the scalp by application of a transparent dressing (Tegaderm) over the electrode followed by fixing with a skin stapler. RESULTS: The needle electrodes were easily, quickly, and firmly positioned even on the nonshaved scalp. The responses of the intraoperative evoked potentials were highly stable and reproducible throughout the operation. CONCLUSION: This fixation method for subdermal needle electrodes on the scalp is safe, reliable, and convenient for intraoperative electrophysiological monitoring of evoked potentials, even if the scalp is not shaved.

Electrodes↗

PubMed1994

Intraoperative neural monitoring. An introduction for perioperative nurses.

Intraoperative neural monitoring is a new science with many potential applications. Anesthesia providers, audiologists, neurophysiologists, and neurologists use intraoperative monitoring to make patient care decisions in the OR. Perioperative nurses' knowledge of anesthesia, anatomy, physiology, surgical procedures, monitoring technology, and electrode application contributes to successful intraoperative monitoring, as does collaboration by the entire surgical team.

Electroencephalography↗

PubMed1996

Total i.v. anaesthesia for transcranial magnetic evoked potential spinal cord monitoring.

Continuous intraoperative monitoring of transcranial magnetic motor evoked potentials (TcMMEP) can warn the surgeon of motor tract damage more effectively than somatosensory evoked potentials. As a non-invasive technique it is especially useful during post-traumatic internal fixation and is applicable whatever the level of the spinal cord at risk. Inhalation and many i.v. anaesthetics block the single pulse TcMMEP but a total i.v. anaesthetic regimen based on methohexitone, alfentanil and ketamine was effective in seven patients undergoing post-traumatic internal fixation. Consistent TcMMEP of 100-1000 mcV were obtained in all patients, with a latency change of only 2 ms above preoperative values. Good cardiovascular stability was maintained during operation.

Adult↗

PubMed1989

Monitoring of intraoperative auditory brainstem responses.

Intraoperative ABR monitoring provides a measure of reassurance when a surgical procedure places the cochlear nerve or its blood supply in jeopardy. ABR monitoring has demonstrated its place in the operating room during retrolabyrinthine vestibular nerve section for vertigo, and in acoustic neuroma operations, when hearing preservation is a high priority in surgical outcome.

Brain Stem↗

PubMed2003

Visual evoked potentials for intraoperative neurophysiologic monitoring using total intravenous anesthesia.

Conflicting reports on the usefulness of intraoperative monitoring of visual function by means of visual evoked potentials (VEPs) initiated this study. In 32 patients without visual problems, VEPs were recorded to evaluate the reliability for intraoperative monitoring with total intravenous anesthesia. All patients underwent noncranial surgery. Using a standard technique, VEPs were recorded preoperatively in the awake patients and after induction of anesthesia during surgery. A total of 1436 intraoperative traces were recorded and analyzed. A minor prolongation of the P100 latency of 8% and a more pronounced attenuation of the P100-N145 amplitude of 60% were observed in the anesthetized patients. In most of the anesthetized patients, a stable recording of VEPs was not obtainable. In 4 patients (12.5%), clearly identifiable VEP peaks were detected in more than 90% of the traces recorded intraoperatively. In 88% of the patients, reproducible VEPs were obtained in less than 75% of the intraoperative traces only. We concluded that with standard recording techniques and total intravenous anesthesia, intraoperative VEP monitoring in surgically anesthetized patients is not reliable.

Adult↗

PubMed2006

Intraoperative electrophysiologic monitoring: considerations for complex spinal surgery.

Intraoperative neurophysiologic monitoring techniques have evolved as the complexity of spinal surgery has increased and the limitations of individual modalities have become apparent. Current monitoring strategies include a combination of techniques directed toward detecting changes in sensory, motor, and nerve root function. Close coordination and communication between the monitoring personnel, surgeon, and anesthesiologist is essential to effective intraoperative monitoring.

Adolescent↗

PubMed1991

Continuous electrical stimulation as a helpful adjunct during intraoperative facial nerve monitoring.

Routine intraoperative monitoring of facial function has been used since 1985. An adaptor has been developed for continuous stimulation (SACS) to be used with the new WR-S8, Monitor/Stimulation The SACS allows the microsurgical instruments and air drills to be electrified and to function as probe tips during surgical dissection. The new WR-S8 Monitor/Stimulator has an ultrasensitive strain gauge that detects facial movement before it is palpable. The remote probe allows an assistant to adjust the current easily. The routine use of facial nerve monitoring with SACS has decreased surgical time, has helped prevent iatrogenic injuries, and has improved our ability to save the facial nerve during otologic and neuro-otologic surgery.

Journal Article↗

PubMed2004

The influence of sample site on intraoperative PTH monitoring during parathyroidectomy.

BACKGROUND: Intraoperative parathyroid hormone (IOPTH) monitoring is common during parathyroidectomy. We hypothesized that sample site (peripheral vs central vein) may impact IOPTH interpretation. METHODS: Two hundred and one patients underwent curative parathyroidectomy for single-gland disease. IOPTH was drawn peripherally (PV) in 114 patients and centrally (CV, jugular vein) in 87 patients. Decrease from baseline IOPTH and the presence of a normal value at 10 and 15 minutes were determined. The slope of IOPTH decay was calculated. These data were compared between sample sites. RESULTS: Median baseline IOPTH was 268 pg/mL (CV) and 191 pg/mL (PV, P = .003). The mean IOPTH decay slopes were -0.75 (PV) and -0.76 (CV, P = NS), and the mean percent IOPTH decrease at 10 minutes was 79% PV and 80% CV (P = NS). At 10 minutes, a > or =50% drop from baseline was seen in 94% (CV) versus 97% (PV) of patients ( P = NS), resulting in a median IOPTH of 40 pg/mL (CV) versus 34 pg/mL (PV, P = .09). By 15 minutes, the central IOPTH had decreased by > or =50% of baseline in 98% of patients ( P = NS when compared to the 10-minute PV site). CONCLUSIONS: IOPTH kinetics are largely the same for PV and CV sample sites, but baseline values are higher with central sampling. Consequently, CV IOPTH levels are generally higher at 10 minutes, but this discrepancy resolves by 15 minutes. The surgeon utilizing CV samples may need to extend the sampling period.

Blood Specimen Collection↗

PubMed2005

Prediction of long-term facial nerve outcomes with intraoperative nerve monitoring.

OBJECTIVE: Evaluate the utility of a statistical equation using two independent intraoperative monitoring parameters in predicting long-term facial nerve function. STUDY DESIGN: Retrospective case review. SETTING: Tertiary care hospital. PATIENTS: Sixty patients undergoing resection of vestibular schwannomas with intraoperative facial nerve monitoring at a single institution. INTERVENTION: All patients underwent microsurgical resection of vestibular schwannomas with the use of intraoperative cranial nerve monitoring. MAIN OUTCOME MEASURE: Final facial nerve outcome measured using the House-Brackmann scale at least 6 months after microsurgical resection. RESULTS: Five out of 60 (8.3%) patients demonstrated significant long-term weakness (i.e., House-Brackmann grade III or worse). Intraoperative monitoring parameters (proximal stimulation threshold, proximal-to-distal response amplitude ratio) were accurate in predicting increased risk of long-term facial nerve dysfunction when used in a logistic regression model. A Student's t test confirmed the equation result was statistically significant in differentiating long-term facial nerve outcomes. CONCLUSION: Patients with immediate weakness are at higher risk of having long-term poor facial nerve function. The use of intraoperative monitoring parameters was reliable in predicting facial nerve outcomes. Patients with permanent facial nerve dysfunction often require rehabilitative procedures. The ability to predict facial nerve outcomes with intraoperative monitoring may allow early rehabilitative procedures to improve quality of life and prevent ocular complications.

Adult↗