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Results for “Monitoring, Intraoperative”

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PubMedDate not supplied

Monitoring peripheral nerve function during external fixation of upper extremities.

Limb lengthening of the upper extremity using external fixation devices is associated with a high risk of neurovascular impairment. To aid early detection of nerve injury, intraoperative monitoring of neural function was performed in five patients undergoing Ilizarov-type circular external-fixator application. The apparatus was applied to the humerus in two cases and to the forearm in the other three cases. The function of ulnar, median, and radial nerves was assessed continuously throughout the surgery by using sensory-evoked potential (SEP) monitoring technique. The responses were elicited by stimulation of these nerves in the distal forearm with recording at Erb's point and over the anterior cervical spine. During apparatus application, radial-response attenuation was identified in two instances. No corrective actions were performed in one case, and the patient had symptoms of radial nerve deficit postoperatively. In the other case, prompt removal of the offending half-pin after the detection of electrophysiologic abnormalities resulted in subsequent response restoration and the avoidance of postoperative nerve dysfunction. Sensory-evoked potential monitoring proved to be a reliable indicator of nerve compromise during external fixation of upper extremities and may be considered a valuable surgical adjunct.

Adolescent↗

PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. I. Relationship of aortic cross-clamp duration, changes in somatosensory evoked potentials, and incidence of neurologic dysfunction.

To determine if intraoperative monitoring of somatosensory evoked potentials detects spinal cord ischemia, we subjected 21 dogs to aortic cross-clamping distal to the left subclavian artery. Group I animals (short-term studies, n = 6) demonstrated decay and loss of somatosensory evoked potentials at 8.5 +/- 1.1 minutes after aortic cross-clamping. During loss of somatosensory evoked potentials, significant decreases in spinal cord blood flow occurred in cord segments below T6. Significant reactive hyperemia occurred without normalization of somatosensory evoked potentials after reperfusion. Fifteen Group II animals (long-term studies) were studied to determine the relationship between duration of spinal cord ischemia (evoked potential loss) and subsequent incidence of paraplegia. Extension of aortic cross-clamping for 5 minutes after loss of somatosensory evoked potentials in six dogs resulted in no paraplegia (mean cross-clamp time 12.7 +/- 0.6 minutes). Prolongation of aortic cross-clamping for 10 minutes after evoked potential loss in nine dogs (mean cross-clamp time 17.6 +/- 0.6 minutes) resulted in a 67% (6/9) incidence of paraplegia 7 days postoperatively (p = 0.02 versus 10 minutes of aortic cross-clamping). These findings demonstrate that simple aortic cross-clamping uniformly results in spinal cord ischemia and that such ischemia is detectable by monitoring of somatosensory evoked potentials. Duration of ischemia, as measured by the time of evoked potential loss during the cross-clamp interval, is related to the incidence of postoperative neurologic injury.

Animals↗

PubMed2005

Intuitive intraoperative ultrasound guidance using the Sonic Flashlight: a novel ultrasound display system.

OBJECTIVE: The Sonic Flashlight (SF) is a new handheld ultrasound (US) display device being developed at our institution. It replaces the standard monitor on a conventional ultrasound (CUS) system with a miniature monitor and half-silvered mirror to reflect real-time US images into the body. With the SF, the imaged body part appears translucent, with the US image appearing to float below the surface of the anatomy, exactly where it is being scanned. The SF merges the patient, US image, instrument, and operator's hands into the same field of view, allowing the user to operate directly on the US image using normal hand-eye coordination. In contrast, CUS procedures result in displaced hand-eye coordination when the operator looks away from the patient to view the CUS monitor. Intraoperatively, the SF may make localizing and accessing tumors, foreign bodies, hematomas, vascular malformations, and ventricles easier and more accurate, especially for those without extensive CUS training. METHODS: In this cadaver study, the SF was used to visualize the brain and guide a needle into an implanted simulated tumor. The needle was inserted both in the US plane and outside of the US plane. INSTRUMENTATION: Sonic Flashlight fifth generation research prototype. CONCLUSION: The needle was easily and intuitively visualized and guided into the lesion, both within and outside of the US plane. By having the US image appear directly beneath the brain surface, the surgeon can easily and quickly guide the needle or surgical instrument to the lesion. The operator's eyes never have to leave the surgical field, as they do with CUS technology. The impact of this device on neurosurgical procedures could be significant. The ease of use, intuitive function, and small instrument size allow the surgeon to quickly localize lesions, confirm surgical positioning, and assess postoperative results.

Brain Neoplasms↗

PubMed1995

Digital replantations under local anaesthesia.

We performed 10 digital replantations under local anaesthesia. Nine were single digit replantations and one case had a digital replantation together with another digit revascularisation. Criteria for patient selection for the local anaesthetic procedure included healthy young individuals, solitary hand injury, ability to understand the procedure and a stable emotional makeup. A combination of 10 ml of lidocaine 1% and 10 ml of bupivacaine 0.5% was used for volar metacarpal block and a dorsal ring block to the base of the digit. The patient was simultaneously sedated with 10 mg diazepam intramuscularly. Standard intraoperative monitoring of blood pressure, continuous electrocardiogram and pulse oximeter were carried out. The average duration of surgery was 3 hours. There was complete pain relief intraoperatively and good postoperative sensory block for an additional 7 to 15 hours. The technical execution of microsurgery was not compromised. All replantations were successful with no complication encountered from the use of local anaesthesia.

Adolescent↗

PubMed1999

Automated prostate recognition: a key process for clinically effective robotic prostatectomy.

Clinical trials of PROBOT, a robotic system for prostate surgery, have shown that robotic surgery of soft tissue can be successful. Monitoring of the progress of the resection has shown to be a necessary feature of an effective robotic system for prostate surgery. It should provide the surgeon with a reliable method of assessing the cavity during resection. An automatic system for intraoperative monitoring of the progress of the resection during robotic prostatectomy consists of two subsystems: real-time intraoperative imaging of the prostate and automatic identification of the contour of the gland on each image. The development of a fully automatic scheme for prostate recognition on transurethral ultrasound scans is reported. A genetic algorithm has been developed to automatically adjust a model of the prostate boundary until an optimum fit to the prostate in a given image is obtained. An analysis of its performance on 22 different ultrasound images showed an average error of 6.21 mm. Use of a genetic algorithm and a constrained prostate model have shown to be a robust way to automatically identify the prostate in ultrasound images. The scheme is able to produce approximate prostate boundaries, without any human intervention, on ultrasound scans of varying quality. In addition to soft tissue robotic surgery, the genetic algorithm technique is also applicable to a wide range of computer assisted surgical techniques.

Humans↗

PubMed1984

Use of intraoperative auditory evoked potentials to preserve hearing in unilateral acoustic neuroma removal.

Twenty-two patients with unilateral acoustic neuromas and preoperative speech discrimination scores of 35% or more had intraoperative monitoring of the electrocochleogram (ECoG) using a transtympanic electrode, and of the brain-stem auditory evoked potentials (BAEP's) using scalp electrodes. Rapid feedback was provided about the status of the cochlear microphonics from the hair cells of the inner ear (CM of the ECoG), the compound action potential of the auditory nerve (N-1 of the ECoG or Wave I of the BAEP's) and the potentials from the lower brain stem (Wave V of the BAEP's). All patients had total removal of the tumor. In 21, the cochlear nerve was anatomically preserved, and 20 had good postoperative facial nerve function. Correlation of tumor size with postoperative hearing was as follows: discrimination scores of more than 35% in three of four patients with 1-cm tumors, two of eight with 1.5-cm tumors, two of six with 2- to 2.5-cm tumors, and one of four with tumors of 3 cm or more. Two other patients with 1.5-cm tumors had discrimination scores of less than 35%, and one patient with a 2-cm tumor had only sound perception. In two patients, the discrimination scores improved. At the end of the operation, all patients with hearing had a detectable N-1, and, when recorded, CM. All but one patient with no hearing had lost N-1, and CM was absent or reduced. Unless Wave V was unchanged, it was a poor predictor of postoperative hearing, and its absence did not preclude preservation of good hearing. The electrophysiological changes during each stage of the operation were analyzed and correlated with events during surgery. Areas in which there was an increased risk of loss of the potentials were determined. In some patients monitoring was unnecessary, because either there were no significant changes or the changes were abrupt and no recovery occurred. However, in other patients, monitoring alerted the surgeon to a possible problem and the method of dissection was altered. Possible mechanisms of hearing loss were suggested from the changes in the recordings.

Adult↗

PubMed1997

Effects of hypothermia and sternal retractors on median nerve somatosensory evoked potentials.

BACKGROUND: Somatosensory evoked potentials (SEPs) are altered by hypothermia, which is often used during cardiopulmonary bypass (CPB). However, the effect of hypothermia on SHP amplitudes is unclear. Also, the sternal retractors used during open heart surgery are reported to cause brachial plexus distension and SEP changes. METHODS: Median nerve SEPs under hypothermic CPB were studied in 29 elective patients scheduled for open heart surgery. In 23 patients who underwent left internal mammary artery (IMA) dissection, the effects of sternal retractors on cortical SEP before the initiation of CPB were investigated. RESULTS: A latency shift of all SEP components was detected when nasopharyngeal temperature decreased from 35.7(SD 0.4) degrees C to 27.8(SD 0.25) degrees C. The mean cortical N20 latency was increased by 39% (P < 0.0001), cervical N13 by 33% (P < 0.0001), and peripheral N9 by 27% (P < 0.0001). The latency changes were reversible when normothermia was restored. The effect of hypothermia on SEP amplitudes was more complex. The mean amplitude of N20 decreased from 2.7 microV to 2.2 microV (P < 0.05) and the amplitude of N13 from 2.5 microV to 2.0 microV (P < 0.0001). In contrast, the N9 component showed an increase from 1.4 microV to 2.1 microV (P < 0.0001) during hypothermia. The sternal retractors did not cause significant cortical SEP amplitude changes during IMA dissection or sternotomy. Also, the latency changes were small, although significant (P < 0.05). CONCLUSION: Despite the moderate amplitude changes produced by hypothermia, SEPs can be successfully monitored during hypothermia. Theoretically, the different behaviour of amplitude in peripheral and cranial components of SEP during hypothermia is interesting. Hypothermia has a more profound effect on synaptic transmission, represented by the cortical N20 latency, than on the peripheral nerve conduction velocity. Intraoperative monitoring of temperature is essential whenever SEPs are recorded. The sternal retractors were not responsible for the intraoperative SEP changes.

Cardiopulmonary Bypass↗

PubMed1997

Asystole as a neurologic sign.

The authors present a case of asystole occurring during dural closure following craniotomy with the patient in the supine position. This 22-year-old woman had a left parietal lobe tumor resected with bipolar cautery. Standard intraoperative monitoring with a left radial arterial line and a right internal jugular central venous catheter was used during the surgery. The anesthetic course was complicated by intraoperative bleeding that responded to three units of fresh frozen plasma. Prior to closure, the operative site appeared dry and intact. After closure, asystole occurred suddenly and resolved with evacuation of 500 ml of blood. It is speculated that the asystole was preceded by an acute increase in intracranial pressure and a subsequent secondary brainstem compression.

Adult↗

PubMed1993

A measure of intraoperative attention to monitor displays.

Vigilance is an important but difficult to measure attribute in anesthesia practitioners. We present a modified standard method to assess intraoperative vigilance toward electronic data displays. The response time to detect a simulated abnormal value on the physiologic monitor was measured. Eight anesthesia residents were studied during 60 surgical procedures. Responses to 439 abnormal values were analyzed. The average response time was 61 +/- 61 s (mean +/- SD), and 56% of the detections were made within 60 s. However, 16% of the abnormal values were undetected during the 5 min that they were displayed. Response times and the rate of missed events were greater during induction of anesthesia (a time of high workload) than during the maintenance or emergence phases of anesthesia. Response times were shorter during procedures on ASA 1 patients than on ASA 3 patients. The results suggest that anesthesiologists usually quickly detect abnormal values on physiologic monitors and that less attention is devoted to monitors during periods of high workload.

Anesthesiology↗

PubMed1989

Fat emboli in bilateral total knee arthroplasty. Predictive factors for neurologic manifestations.

Fat embolism after bilateral total knee arthroplasty (TKA) occurred in 12% of the authors' patients having bilateral TKA with intramedullary instrumentation. Usually embolism was manifested as neurologic changes, most often changes of mental status. Death is a potential consequence, and this occurred in one patient. The present authors believe that fat embolism is not predictable preoperatively and propose that intraoperative guidelines can be used to reduce risk of this complication. Intraoperative monitoring by a Swan-Ganz catheter will permit measurement of the pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary wedge pressure. A sustained rise of any of these would be an indication to abort the second knee operation. If Swan-Ganz catheter is not available, a sustained fall of oxygen saturation to 90% or lower can be used as a criterion. The risk for fat embolism is increased with the use of intramedullary instrumentation, and the above guidelines are recommended for operations with this type of instrumentation. A fluted intramedullary rod and vent holes should be used.

Catheterization, Swan-Ganz↗

PubMed1982

Monitoring of cortical somatosensory evoked potentials to determine the safety of sacrificing the anterior cerebral artery.

Cortical somatosensory evoked potentials (SSEPs) reflect the functional integrity of somatosensory pathways from the site of stimulation to the primary somatosensory cortex. We used intraoperative monitoring of cortical SSEPs to determine whether the right anterior cerebral artery (RACA), the major feeding vessel of a large arteriovenous malformation (AVM), could be sacrificed without compromising sensorimotor function in the left lower extremity. The SSEPs recorded after test occlusion of the RACA showed preservation of the initial cortical positivity, and the RACA was divided. The AVM was excised completely, and the patient suffered no neurological deficit.

Adult↗

PubMed1996

Intraoperative vagal nerve monitoring.

A variety of benign and malignant neoplasms occur in the superior cervical neck, parapharyngeal space or the infratemporal fossa. The surgical resection of these lesions may result in postoperative iatrogenic injury to the vagus nerve with associated dysfunctional swallowing and airway protection. Anatomic and functional preservation of this critical cranial nerve will contribute to a favorable surgical outcome. Fourteen patients with tumors of the cervical neck or adjacent skull base underwent intraoperative vagal nerve monitoring in an attempt to preserve neural integrity following tumor removal. Of the 11 patients with anatomically preserved vagal nerves in this group, seven patients had normal vocal cord mobility following surgery and all 11 patients demonstrated normal vocal cord movement by six months. In an earlier series of 23 patients with tumors in the same region who underwent tumor resection without vagal nerve monitoring, 18 patients had anatomically preserved vagal nerves. Within this group, five patients had normal vocal cord movement at one month and 13 patients demonstrated normal vocal cord movement at six months. This paper will outline a technique for intraoperative vagal nerve monitoring utilizing transcricothyroid membrane placement of bipolar hook-wire electrodes in the vocalis muscle. Our results with the surgical treatment of cervical neck and lateral skull base tumors for patients with unmonitored and monitored vagal nerves will be outlined.

Adolescent↗

PubMed2006

Intraoperative parathyroid hormone monitoring during parathyroidectomy for hyperparathyroidism in waiting list and kidney transplant patients.

This report describes the use of the intraoperative parathyroid hormone (ioPTH) assay during parathyroidectomy in waiting list and transplanted patients. ioPTH levels were determined in 40 patients on the waiting list for kidney transplantation with secondary hyperparathyroidism who underwent subtotal parathyroidectomy and 9 transplanted patients with tertiary hyperparathyroidism who underwent removal of hyperplasic glands. Rapid PTH levels decreased significantly at each time period; the percentage decrease in rapid PTH levels was 61.3% among patients with IPT II and 70.2% in patients with IPT III at 10 minutes and 86.5% in patients with IPT II and 91% in patients with IPT III at 15 minutes after excision of hypersecreting parathyroid tissue. A decrease of 50% or more from baseline PTH levels at 10 minutes and/or a decrease of 85% or more at 15 minutes predicted successful removal of abnormal parathyroid glands. The application of this technique during subtotal parathyroidectomy has proved useful for correct excision of parathyroid glands among waiting list patients with IPT II, while in kidney transplant patients with IPT III it allowed removal of only the pathological glands with a limited surgical approach.

Adult↗

PubMed1987

Somatosensory evoked potentials after sequential extremity stimulation: a new method for improved monitoring accuracy.

A new method for improving the accuracy of somatosensory evoked potential (SEP) monitoring is described. Two extremities are stimulated at 5 Hz, with an interextremity stimulus interval of 100 ms. Information from a "control" extremity, such as an arm during scoliosis operation, may allow more rapid and accurate interpretation of changes in SEPs during intraoperative monitoring.

Computers↗

PubMed1986

Electrocautery and pacemakers: management of the paced patient subject to electrocautery.

Electrocautery, commonly used during surgery to maintain hemostasis, can have significant detrimental effects in the paced patient. Damage to the pulse generator, reprogramming of the pacemaker, changes in the capture threshold, and ventricular fibrillation can all be induced by electrocautery. Familiarity with the particular pacemaker in use is critical in minimizing these adverse effects. Preoperative evaluation of the patient's dependence on the pacemaker and evaluation of pacemaker function should be performed and documented. We recommend close intraoperative monitoring of heart rate and rhythm, and suggest that a pacemaker programmer be on hand in the surgical suite during the operation. A postoperative check of pacemaker function should be carried out so that electrocautery-induced pacemaker malfunction will not go unnoticed or uncorrected. Three cases are presented which clearly illustrate these points.

Aged↗

PubMed1981

Intraoperative anticoagulation in cardiovascular surgery.

The optimal heparin dose to prevent intraoperative thrombosis or excessive bleeding during the occlusive phase of cardiovascular operations has not been determined. Therefore, we studied the kinetics of heparin effect in 28 patient undergoing peripheral vascular and cardiac operations. The activated clotting time (ACT) was measured in seconds by an electronic clot timer. The maximum ACT after initial heparin administration, the time to reach maximum ACT, and the half-time of heparin effect (t1/2) were determined. The anticoagulant effect of a given dose of heparin varies greatly among patients. No correlation was found between the t1/2 and the dosage of heparin administered. Despite higher doses of heparin administered to cardiac patients, the t1/2 in cardiac and vascular patients was not significantly different. Four patients received the same dose of heparin preoperatively and intraoperatively in an effort to predict the intraoperative effect. The times to maximum effect were the same but t1/2 intraoperatively was longer. These results indicate: (1) maximum heparin effect occurs later than previously believed and is different for cardiac and peripheral vascular patients; (2) the recommendation to give more heparin based on the 5-minute ACT is not valid; (3) individual response to a standard dose of heparin is unpredictable, both in duration and maximum effect; and (4) intraoperative monitoring of the heparin effect is practical and is the only way that any consistent, specific and point of heparin can be achieved.

Aged↗

PubMed2002

Magnetic stimulation of the central and peripheral nervous systems.

Since 1985, when the technique of transcranial magnetic stimulation (TMS) was first developed, a wide range of applications in healthy and diseased subjects has been described. Comprehension of the physiological basis of motor control and cortical function has been improved. Modifications of the basic technique of measuring central motor conduction time (CMCT) have included measurement of the cortical silent period, paired stimulation in a conditioning test paradigm, repetitive transcranial magnetic stimulation (rTMS), and peristimulus time histograms (PSTH). These methods allow dissection of central motor excitatory versus inhibitory interplay on the cortical motor neuron and its presynaptic connections at the spinal cord, and have proven to be powerful investigational techniques. TMS can be used to assess upper and lower motor neuron dysfunction, monitor the effects of many pharmacological agents, predict stroke outcome, document the plasticity of the motor system, and assess its maturation and the effects of aging, as well as perform intraoperative monitoring. The recent use of rTMS in the treatment of depression and movement disorders is novel, and opens the way for other potential therapeutic applications.

Central Nervous System↗

PubMed2002

Minimally invasive electrodiagnostic monitoring in epilepsy surgery.

A new method of obtaining electrographic recordings from endoscopically-based intraventricular monitoring was performed in three patients with intractable epilepsy, who subsequently underwent open resective neurosurgery. As a minimally invasive procedure, it was associated with no peri-operative complications, and electrical intraoperative monitoring of the epileptogenic focus yielded excellent results.

Brain Diseases↗