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At least 721 records · Page 40Linked to original sources
PubMed1994

Con: intraoperative myocardial ischemia is not benign.

The principal importance of intraoperative ischemia is its consistent association with adverse outcome. In coronary artery surgery the finding of prebypass ischemia is an important predictor, and postbypass ischemia is a critical predictor of adverse outcome. One in three patients with postbypass ischemia will suffer an adverse outcome in CABG. Furthermore, prevention of postbypass ischemia may improve outcome in CABG. Clearly, intraoperative ischemia in CABG surgery is an ominous sign that should be regarded with the utmost concern by anesthesiologists. In noncardiac surgery, intraoperative ischemia also indicates about a one in three chance of adverse outcome. Although it is less sensitive than postoperative ischemia, it may have superior positive predictive power and specificity. Most importantly, intraoperative monitoring for ischemia is currently available to most patients, whereas extended postoperative monitoring is not. The finding of intraoperative ischemia defines a high-risk group of patients who may merit special monitoring and treatment. To regard intraoperative ischemia as benign would be inconsistent with available information.

Cardiopulmonary Bypass↗
PubMed1989

Intraoperative temperature monitoring sites in infants and children and the effect of inspired gas warming on esophageal temperature.

This study tested the hypotheses that 1) temperatures of "central" sites are similar in infants and children undergoing noncardiac surgery and 2) airway heating and humidification increases distal esophageal temperature. Twenty children were randomly assigned to receive 1) active airway humidification using an airway heater and humidifier set at 37 degrees C (N = 8), 2) passive airway humidification using a heat and moisture exchanger (N = 6), or 3) no airway humidification and/or heating (control, N = 6). There were no statistically significant differences between tympanic membrane, esophageal, rectal, and axillary temperatures. The temperatures of the peripheral skin surface (forearm and fingertip) were significantly lower than tympanic membrane temperature and significantly different from each other. Although esophageal and tympanic membrane temperatures in the entire group were similar, esophageal temperatures in patients receiving active and passive airway humidification were about 0.35 degrees C above tympanic temperatures after induction of anesthesia. In contrast, esophageal temperatures in patients without airway humidification were 0.25 degrees C below tympanic temperatures after induction of anesthesia. Esophageal-tympanic membrane temperature differences in the patients given active and passive humidification differed significantly from the corresponding sum in the control group at all times, but not from each other.

Anesthesia, Inhalation↗
PubMed2001

Hypertonic saline solution: a safe alternative to mannitol 18% in neurosurgery.

BACKGROUND: To evaluate the usefulness of hypertonic saline solutions (HTS) as an alternative to mannitol in neurosurgery. METHODS: Thirty patients subjected to craniotomy for supratentorial cerebral tumors were randomly divided in to three Groups: M: had mannitol 0.5 g.kg-1 as bolus at the start of skin incision, and postoperatively 0.5 g.kg-1 daily three times a day for 3 days (72 hrs); HM: had mannitol 0.25 g.kg-1 as bolus at the start of skin incision plus 3% HTS, 20 ml.h-1 intraoperatively and mannitol 0.25 g.kg-1 daily three times a day for 3 days plus HTS in the concentration of 3% in the first day and 2% and 1% the second and the third day after surgery; H: had 3% HTS 3.5 ml kg-1 as bolus at the start of skin incision plus 3% HTS, 20 ml hr-1 intraoperatively and 3% HTS, 20 ml h-1 on the first day and 2% and 1% the second and the third day after surgery. FR, MAP, ICP, CVP and diuresis were continuously monitored intraoperatively and postoperatively for 72 hrs. ICP was monitored intraoperatively until dural opening and in the postoperative period for 72 hrs at least. RESULTS: Diuresis was increased in the first and second Group (M and HM) more than in the H Group especially in the postoperative period, but this change was not a significative one (35.31 ml.kg-1.h-1+/-4.57 and 36.56+/-3.92 vs 3.23 ml.kg-1.h-1). Mean serum Na+ values declined in the postoperative period, in Groups M and MH and remained stable in the postoperative period in the Group H (137.6+/-7 mEq.l-1 and 136.5+/-6.5 mEq.l-1 vs 139.2+/-5 mEq.l-1). Serum osmolality increased significantly in the postoperative period in group H and remained unchanged in the same period in Group M and MH. Potassium values declined significantly during the whole period in all groups but remained in a normal clinical range. CVP values decreased in Groups M and MH in the postoperative period, and increased although not significantly in the postoperative period in the Group H patients. Ht values declined significantly in all groups without differences among the groups although the reduction was greater in group H. CONCLUSIONS: HTS can safely be used in humans they obtain a reduction of ICP without reducing CVP, serum osmolality and Na+ serum values. Our data underline the possibility of their use as an alternative to mannitol in the treatment of patients scheduled for intracranial surgery, especially when multiple doses are needed.

Adolescent↗
PubMedDate not supplied

Sensitivity of spinal cord monitoring to intraoperative events.

Intraoperative somatosensory evoked potentials in 50 patients were reviewed; each waveform was correlated with intraoperative surgical events and conditions. Twenty-two patients maintained reproducible waveforms and awoke without neurological deficit. Two patients had random waveform changes not correlated with a surgical event and awoke without deficit. Twelve patients showed waveform changes temporally related to circumstances that might endanger cord function; two of these awoke with transient neurological abnormality. Satisfactory waveforms were not obtained from 14 patients. Somatosensory evoked potential monitoring in scoliosis surgery appears to be sensitive, but may not be sufficiently specific; waveform changes do not necessarily indicate objective neurological damage.

Adolescent↗
PubMed1991

Spinal cord monitoring. Results of the Scoliosis Research Society and the European Spinal Deformity Society survey.

The Scoliosis Research Society (SRS) and the European Spinal Deformity Society (ESDS) membership was surveyed regarding the use of intraoperative monitoring of somatosensory evoked potentials in spinal surgery. A total of 242 people responded, with 188 using intraoperative monitoring. A second survey was distributed detailing the technical aspects of monitoring, of which 71 were returned. A total of 342 neurologic deficits were reported to have occurred with monitoring in place. Two hundred forty-six (72%) were accurately detected, and 96 (28%) were not detected by sensory cord evoked potentials (SCEP). There were 1,003 false-positive cases reported. The incidence of false-negative cases was related to those not monitoring both latency and amplitude, to using fewer recording electrodes, and with those surgeons doing more kyphosis corrections.

Europe↗
PubMed2000

Changes of bilateral palmar skin temperature in transthoracic endoscopic T-2 sympathectomy.

OBJECT: Transthoracic endoscopic T-2 sympathectomy is currently the treatment of choice for palmar hyperhidrosis (PH). Intraoperative monitoring of palmar skin temperature (PST) is often used to assess the adequacy of sympathetic ablation. The aim of this study was to investigate the time course of PST changes during the operation and to determine factors involved in the sympathetic modulation of the palmar skin blood flow. METHODS: Eighty-one patients with PH underwent bilateral transthoracic endoscopic sympathectomy of T-2 in which continuous intraoperative PST monitoring was used. Palmar skin temperature data, recorded every 30 seconds throughout the operation, were plotted against time, and a graph of two PST curves was obtained in each case. A multiphasic curve pattern of great similarity was observed in nearly 70% of cases. Specific PST readings at different operative stages were collected and averaged for all cases. The trend of PST changes in response to different procedures during the operation was analyzed. It was found that unilateral procedures caused simultaneous bilateral PST alterations. In almost all cases, bilateral PST was dramatically lowered when unilateral skin incision and intercostal muscle dissection were performed. The temperature remained low until the T-2 sympathectomy was finished on one side. In addition, unilateral T-2 sympathectomy induced synchronous elevation of bilateral PST. However, the ipsilateral response was significantly stronger than that on the contralateral side. CONCLUSIONS: Although intraoperative monitoring of PST is a reliable guide for surgeons performing endoscopic transthoracic sympathectomy, it is important to realize that PST fluctuates at different stages during the operation and that surgical procedures themselves can significantly influence PST readings. The PST data recorded at specific time points, therefore, can be misleading in terms of accuracy and the completeness of ablation of the target sympathetic ganglia, especially when the sympathetic trunk or ganglia are anatomically aberrant.

Adolescent↗
PubMed2001

Real-time intraoperative neurophysiological monitoring.

We discuss the utilization of signal processing techniques during surgical procedures. These techniques are used to provide real-time monitoring of nervous system function. We describe the historical development of these techniques and the hardware and software that have been used to implement them.

Algorithms↗
PubMedDate not supplied

[A practical guide to carrying out neurophysiological monitoring in spine surgery].

INTRODUCTION AND AIMS: The main purposes of intraoperative monitoring during spine surgery are to avoid damage to nerve structures, to guide the surgeon in the extension of the correction, to identify structures and to ensure the patient receives the best possible attention. Several multicentre studies have shown that performing neurophysiological monitoring of spinal cord functioning during spine surgery reduces the incidence of post surgical neurophysiological injury by up to 50%. A number of different neurophysiological tests have been developed to monitor spinal cord functioning during surgery but no agreement has been reached about which is the best method. In this work, the Spanish Society of Clinical Neurophysiology, through a panel of experts, has surveyed the main monitoring techniques used during spine surgery and has drawn up a series of best practice guidelines. DEVELOPMENT: None of the techniques described to date is totally free of drawbacks. Nevertheless, what authors do agree about, both in the Spanish and international literature, is the advisability of having several types of potential available so that they can be used if and when the neurophysiologist sees fit, while also allowing the disadvantages of each different type to be compensated, which in turn means an increased degree of safety for the patient. CONCLUSIONS: Monitoring requires a multidisciplinary team and the neurophysiologist must be fully competent in this area. With this guide, the Spanish Society of Clinical Neurophysiology conducts a review of the different techniques available and lays down the criteria for interpreting the results and the risk criteria of the most important techniques.

Electromyography↗
PubMed1988

Direct noninvasive monitoring of spinal cord motor function during thoracic aortic occlusion: use of motor evoked potentials.

Spinal cord monitoring during thoracic aneurysmectomy by somatosensory evoked potentials has been criticized for its failure to measure anterior (motor) spinal cord function. We have developed a clinically applicable, noninvasive technique for intraoperative monitoring of motor evoked potentials (MEP), which allows direct functional assessment of spinal cord motor tracts during thoracic aortic occlusion. Twelve dogs underwent continuous intraoperative monitoring of MEP before, during, and after thoracic aortic cross-clamping. Motor tract response to noninvasive cord stimulation (5 to 10 mA, 0.02 msec, 4.3 H2) was recorded by subcutaneous electrodes placed along the length of the spine (T-10, L-1, and L-4). Six animals (group I) subjected to aortic cross-clamping alone demonstrated a characteristic time- and level-dependent deterioration and loss of MEP. Ischemic cord dysfunction (as determined by time from clamping to loss of MEP) progressed from the distal to the proximal cord (L-4 = 11.3 +/- 1.5 minutes; L-1 = 14.9 +/- 2.3 minutes; T-10 = 16.9 +/- 2.3 minutes; p less than 0.05 between all levels). Reperfusion of the distal aorta 20 minutes after clamping resulted in MEP return that progressed from the proximal (T-10) to distal (L-1 and L-4) cord. In another six animals (group II), distal perfusion (mean blood pressure = 95 mm Hg) was maintained for 1 hour after cross-clamping by left atrial-femoral artery bypass. Normal configuration and amplitude of MEP was maintained throughout the cross-clamping period. These data suggest that distinctive changes in MEP indicative of reversible ischemia of spinal cord motor tracts occur after aortic cross-clamping. Such ischemia begins in the most distal cord, exhibits upward progression with time, and can be prevented by maintenance of adequate distal aortic perfusion. Clinical use of MEP monitoring during thoracic aneurysmectomy may provide a method for intraoperative assessment of the adequacy of motor tract perfusion.

Animals↗
PubMed2003

Recurrent laryngeal nerve monitoring in thyroid and parathyroid surgery: the University of Michigan experience.

OBJECTIVES/HYPOTHESIS: Intraoperative monitoring of the recurrent laryngeal nerve (RLN) is finding increasing acceptance during thyroidectomy. Recently, a laryngeal surface electrode was introduced to enable another form of noninvasive monitoring of the RLN. The present report examines the University of Michigan experience with RLN monitoring using the postcricoid surface electrode. STUDY DESIGN: All patients undergoing partial or total thyroidectomy or parathyroidectomy from January 1999 to July 2001 were considered candidates for the study. Audiologists trained in intraoperative electrophysiological techniques performed all of the monitoring. METHODS: Data collected on each patient included 1) stimulation threshold for a laryngeal compound muscle action potential on initial RLN identification, 2) stimulation threshold of the laryngeal compound muscle action potential on completion of the procedure, and 3) flexible fiberoptic evaluation of the larynx at the initial postoperative visit and at the 3-month follow-up visit. The average duration of follow-up was 9.8 months with a range of 3 to 60 months. RESULTS: The average minimum current required for stimulation on first identification of all nerves was 0.57 mA (+/-0.48 mA). After completion of the procedure a mean threshold level of 0.42 mA (+/-0.55 mA) was obtained during direct RLN stimulation. Post-dissection stimulation of the RLN on the side of tumor dissection was 0.92 mA (+/-0.65 mA) compared with a stimulation threshold of 0.76 mA (+/-0.57 mA) for the nontumor side. CONCLUSIONS: Electromyographic monitoring of the RLN using a postcricoid surface electrode provides a safe, simple, and effective method for intraoperative monitoring during thyroid or parathyroid surgery. Further, evoked electromyography confirms RLN integrity at the conclusion of surgery.

Action Potentials↗
PubMed1988

Anesthesia and evoked potentials: overview.

Evoked potentials are increasingly used for intraoperative monitoring. Their use is based on their ability to detect early changes caused by surgical maneuvers which may result in post operative deficits. However, not all changes are surgically related and any decrease in the non surgical causes of evoked potential changes increases the yield of intraoperative monitoring. In this review I will discuss the anesthetic effects on evoked potentials; these include a general description of the anesthetic effects on evoked potentials followed by the effects of premedication, induction, and maintenance agents. Also, described are the effects of adjunct anesthetic agents and techniques. Changes related to anesthesia are not similar and the knowledge of such differences is essential for the planing of anesthesia during the use of evoked potentials. An out line of the anesthetic techniques are described at the end of this review.

Adjuvants, Anesthesia↗
PubMed1985

Retrolabyrinthine vestibular neurectomy with and without monitoring of eighth nerve potentials.

Retrolabyrinthine vestibular neurectomy is a safe and effective treatment for Meniere's disease and inner ear vertigo. Hearing was maintained within 20 dB of the preoperative level in 83% of our patients and speech discrimination scores were preserved within 20% in 80%. Intraoperative monitoring of audiometric evoked potentials, employed to study the possible causes of hearing loss, provided rapid, sensitive detection of trauma to the auditory system. Our patients benefited from this technique--those who underwent retrolabyrinthine vestibular nerve section, as well as those who experienced acoustic neuroma surgery, where hearing preservation is a goal. Direct intraoperative monitoring of eighth nerve function continues to be a standard part of our surgical practice.

Ear, Inner↗
PubMed1985

[Monitoring of therapeutic neuroradiologic examination and therapeutic procedures using evoked potentials].

Interventional neuroradiology makes use of different diagnostic and therapeutic catheterization techniques. Treatments performed are local intraarterial thrombolytic therapy, embolization and occlusion of brain supplying arteries, percutaneous transluminal angioplasty and intraarterial application of drugs. These treatments make it most important to check the patients neurological state during the procedure. Intraoperative monitoring of evoked potentials offers the opportunity to get objective information about changes in certain central nervous system functions even in anaesthesized patients. Usually intraoperative monitoring is performed to obtain information whether the function of structures at risk remains stable or is altered by the operation. This represents a more passive, observing way of monitoring. During interventional neuroradiology one is enabled to take additionally a more active and experimental way of monitoring by using the advantages of special catheter techniques like series of reversible balloon occlusion or intraarterial drug application. This leads to a dialogue between the radiologist and the neurophysiologist about the safety or the risk of the next step during a procedure. There are mainly two types of new information that can be achieved by active monitoring: the identification of functional territories of single or multiple feeding vessels and new insights into hemodynamics and the establishing of new sufficient collaterals. We have used intraoperative neuromonitoring in 35 patients during interventional neuroradiology. Our findings will be summarized and the usefulness of the different monitoring methods will be discussed.

Amobarbital↗
PubMed1991

A prospective study of intraoperative pulse oximetry failure.

Since pulse oximetry is now an ASA standard for intraoperative monitoring, we sought to determine the intraoperative failure rate for this device. We prospectively evaluated the intraoperative failure rate of our pulse oximeters at the four University of Washington Hospitals (University of Washington Medical Center, Veterans Affairs Medical Center [VAMC], Children's Hospital and Medical Center, and Harborview Medical Center [HMC]) recorded from April 1989 to August 1989. We defined failure as the inability to obtain any oximetry reading for a cumulative period of more than 30 minutes during any anesthetic procedure after all equipment malfunctions had been eliminated. Our puse oximeters failed in 124 of 11,046 cases studied; this is a failure rate of 1.12%, which ranged from 0.56% at HMC to 4.24% at VAMC. The failure rate at VAMC (4.24%) was significantly higher than the other hospitals (p less than 0.001). Those cases associated with the pulse oximeter failure had the following characteristics: (1) an ASA status of 3 or higher, (2) lengthy operations, and (3) elderly patients. When the device did fail in a patient, it did not function for 32% of the mean anesthesia time. We conclude that the intraoperative use of the pulse oximetry can provide information about blood oxygen saturation in most patients. However, in approximately 1% of the patients we studied in the operating room, mechanically functioning pulse oximeters failed to provide readings of blood oxygen saturations during routine operative use.

Equipment Failure↗
PubMed1991

Continued experience with intraoperative angioscopy for monitoring infrainguinal bypass grafting.

Intraoperative angioscopy provides direct, in vivo, three-dimensional visualization of the interior of the blood vessels and grafts. We have shown previously that with the application of the basic principles of irrigation and with a dedicated irrigation pump that routine intraoperative angioscopy can be performed with consistent high quality results during lower extremity revascularization. In our total experience with angioscopy as a monitoring procedure during infrainguinal bypass grafting, 259 intraoperative angioscopies, during 63 femoropopliteal and 196 distal bypass grafts, were performed from May 1, 1987, to October 31, 1989. Mean total irrigation fluid used in the study was 448 ml (range, 0 to 1400 ml) with good visual quality in more than 80% of the studies. The overall failure rate was 1.5%. No complications were directly attributable to the insertion of the angioscope or the use of the pump. Based on the angioscopic findings, 124 clinical or surgical decisions were made in 259 of the angioscopies. The incidence of graft failure in this study was 8.1% (less than 30 days) and 4.8% (greater than 30 days) with a mean follow-up of 272 days. Direct inspection of the interior of the graft and native vessels at the time of surgery has resulted in the recognition of previously unsuspected vein-graft pathology. Angioscopy as the sole monitoring procedure for infrainguinal bypass grafting is safe, effective, and reliable and may not only improve the durability of these grafts but may improve our understanding of the pathogenesis of graft failure and of the progression of the underlying atherosclerotic disease.

Adult↗
PubMed2005

Update on anesthetic and metabolic effects during intraoperative neurophysiological monitoring (IONM).

Various agents are utilized in the operating room to produce anesthetic effects. These include barbiturates, halogenated inhalation agents, narcotics, non-barbiturate induction agents, and benzodiazepines. These agents have variable effects upon the EEG and EP (evoked potential) waveforms at different anesthetic levels. Metabolic changes such as body temperature and blood pressure can also elicit changes in the EEG and EPs.

Anesthetics↗