SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Two zero-phase digital filters for use in recording brain-stem auditory evoked potentials for clinical diagnostic purposes, and for use in intraoperative monitoring, are described. Practical experience in the use of these filters and the advantages and disadvantages of time domain filtering are discussed.
Intraoperative spinal cord evoked potentials (SCEPs) to median nerve stimulation were detected subpially from the dorsal surface of the cervical spinal cord in 5 patients with cervical syringomyelia and were compared to normal SCEPs obtained from the unaffected side in 6 patients during intraoperative monitoring of dorsal root entry zone lesion. Normal SCEP began with a positive deflection P9 and a complex N11/N13 with several low amplitude short potentials superimposed on the N11/N13. The complex was followed by a second negative potential N2 and a late prolonged positivity, P. In the 4 patients in whom median nerve somatosensory evoked potentials (SEPs) were present preoperatively, SCEP consisted of the N11 potential and the following low amplitude short (LAS) potentials, while the N13 wave was missing. In the fifth patient, in whom the preoperative median nerve SEP was missing, SCEPs were of much lower amplitude and shorter duration than normal. The potentials N2 and P were not recorded in any of our 5 patients. Changes in N13 wave, N2 and P potentials noted in syringomyelia were presumed to be the result of destruction of the spinal cord dorsal horn neurons caused by spinal cord central cavitation.
The effects of high doses of fentanyl (group F), sufentanil (group S), and alfentanil (group A) on posterior tibial nerve somatosensory cortical evoked potentials were studied in 30 patients scheduled for elective valve replacement surgery. Anesthesia was induced with either fentanyl, 75 microg/kg, sufentanil, 5 microg/kg, or alfentanil, 125 microg/kg. The lungs were ventilated with oxygen/air. A bolus dose of fentanyl, 25 microg/kg, was given 30 minutes after induction of anesthesia in group F. Anesthesia was maintained with a continuous infusion of sufentanil, 5 microg/kg/h, in group S, or alfentanil, 500 microg/kg/h, in group A. Latencies of the peaks of the primary cortical complex (P1, N1, P2) increased by 1 to 2 ms after induction of anesthesia, although this was significant (P < 0.01) only for P1 and N1 in groups F and S. N2 latency increased significantly (P < 0.01) by 6 to 10 ms in all groups. P1-N1 amplitude did not change after induction of anesthesia. N1-P2 amplitude decreased significantly (P < 0.01) to 60%-70% of preinduction values in groups F and S. P2-N2 amplitude decreased significantly (P < 0.01) to 60%-70% of preinduction values in all groups. P1, N1 and P2 latencies did not change significantly from the post-induction values in the period preceding cardiopulmonary bypass (75 +/- 16 minutes) in groups F and S. In group A significant changes were observed only for N1 and P2 latency (P < 0.01). During this period there was a further gradual increase in N2 latency and amplitudes remained stable, except P1-N1 amplitude in group F, which decreased significantly (P < 0.05). A bolus dose of fentanyl, 25 microg/kg, given in group F at 30 minutes after induction of anesthesia did not change latencies and amplitudes. No significant differences in latency or amplitude were found at any time among the three study groups. It is concluded that anesthesia with high doses of fentanyl, sufentanil, or alfentanil is a suitable technique when intraoperative monitoring of posterior tibial nerve somatosensory cortical evoked potentials is indicated.
STUDY OBJECTIVE: To determine whether data recorded by an information management system is significantly different from that recorded manually. DESIGN: A comparison was made between 13 handwritten and 13 computer-generated anesthesia records by calculating the frequency with which recorded variables were outside predetermined acceptable ranges. Five physiologic variables [systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), end-tidal partial pressure of carbon dioxide (PETCO2), and oxygen saturation by pulse oximeter (SpO2)] were compared during the initial 1 1/2 hours of operation. SETTING: Surgical suite at a university-affiliated hospital. PATIENTS: Thirteen adult patients scheduled for operations that required general anesthesia for longer than 1 1/2 hours. INTERVENTION: In addition to the traditional handwritten anesthesia records, an information management system (ARKIVE Patient Management System, DIATEK, San Diego, CA) was used to collect data from each case. MEASUREMENTS AND MAIN RESULTS: No significant differences were found between the methods in the frequency of elevated SBP, elevated DBP, and tachycardia. However, the manual records showed low SBP, DBP, and HR with a significantly lower frequency (2%, 11%, 1%, respectively) than the automated records (6%, 26%, 5%, respectively; p < 0.01). The automated PETCO2 readings were higher than the upper limit (40 mmHg) with a higher frequency (18%) than the manual records (3%; p < 0.01). On the automated records, SpO2 was noted to be 90% or less on two occasions, but significant desaturation was noted only once on the manual charts. CONCLUSIONS: Observer bias, missed readings, and errors of memory, which affect manual anesthetic records, may cause significant inaccuracy and may be avoided by using automated records generated by information management systems.
This prospective study was performed in 17 consecutive patients continuously monitored intraoperatively and postoperatively for cardiac function with two-dimensional (2D) TEE. Prior to systematic evaluation of spinal cord imaging by 2D TEE, the aims of this study were to determine: (1) the feasibility of such imaging, and (2) the relationship between spinal cord images and fixed structures (like vertebral bodies); 7.5 +/- 2.3 spinal segments were identified in the patients. There is a close relationship between the distance of the probe from the teeth and the intervertebral disc. Successful imaging of the spinal cord was achieved in all 17 patients with visualization of discs, spinous processes, spinal canal, and a pulsating spinal cord. Further studies are needed to better define the potential applications of this new technique: detection of spinal cord trauma, visualization of a thoracic epidural catheter, and successful preservation of spinal cord vascularization during thoracic aortic surgery.
Transcranial Doppler and, if possible, measurement of intracranial pressure (ICP) allow preoperative diagnosis of acute intracranial hypertension (ICH) after brain trauma. The main goal of the anaesthesiologist is to prevent the occurrence of secondary brain injuries and to avoid cerebral ischaemia. Treatment of high ICP is mainly achieved with osmotherapy. High-dose mannitol administration (1.4 to 2 g/kg given in bolus doses) may be considered a better option than conventional doses, especially before emergency evacuation of a cerebral mass lesion. Hypertonic saline seems as effective as mannitol without rebound effect and without diuresis increase. Haemostasis should be normalized before neurosurgery and invasive blood pressure monitoring is mandatory. For anaesthesia induction, thiopental or etomidate may be used. In case of ICH, halogenated and nitrous oxide should be avoided. Until the dura is open, mean arterial pressure should be maintained around 90 mmHg (or cerebral perfusion pressure around 70 mmHg). If a long-lasting (several hours) extracranial surgery is necessary, ICP should be monitored and treatment of ICH should have been instituted before.
OBJECTIVE: To address the limitations of standard electromyography (EMG) facial nerve monitoring techniques by exploring the novel application of multi-pulse transcranial electrical stimulation (mpTES) to myogenic facial motor evoked potential (MEP) monitoring. METHODS: In 76 patients undergoing skull base surgery, mpTES was delivered through electrodes 1cm anterior to C1 and C2 (M1-M2), C3 and C4 (M3-M4) or C3 or C4 and Cz (M3/M4-Mz), with the anode contralateral to the operative side. Facial MEPs were monitored from the orbicularis oris muscle on the operative side. Distal facial nerve excitation was excluded by the absence of single pulse responses and by onset latency consistent with a central origin. RESULTS: M3/M4-Mz mpTES (n=50) reliably produced facial MEPs while M1-M2 (n=18) or M3-M4 (n=8) stimulation produced 6 technical failures. Facial MEPs could be successfully monitored in 21 of 22 patients whose proximal facial nerves were inaccessible to direct stimulation. Using 50, 35 and 0% of baseline amplitude criteria, significant facial deficits were predicted with a sensitivity/specificity of 1.00/0.88, 0.91/0.97 and 0.64/1.00, respectively. CONCLUSIONS: Facial MEPs can provide an ongoing surgeon-independent assessment of facial nerve function and predict facial nerve outcome with sufficiently useful accuracy. SIGNIFICANCE: This method substantially improves facial nerve monitoring during skull base surgery.
OBJECTIVE: Cerebral injury, in both overt and subtle forms, is common following cardiac surgery. Current methods of assessment, most commonly neuropsychological testing, have several limitations and do not accurately define the anatomical and functional injury that occurs. We have assessed the degree of cerebral injury following on-pump and off-pump cardiac surgery using functional magnetic resonance imaging and correlated this with the severity of microembolism as measured by transcranial Doppler ultrasound. METHODS: Sixteen patients undergoing cardiac surgery (8 off-pump coronary artery bypass grafting (CABG), 4 on-pump CABG and 4 open-heart surgery) underwent functional magnetic resonance imaging of the brain pre-operatively and 4 weeks post-operatively. The functional magnetic resonance images demonstrated brain activation during performance of a verbal working memory paradigm. Each patient had continuous transcranial Doppler monitoring intraoperatively using a recently validated technique (multirange, multifrequency Doppler) that allows rejection of artefacts and separation of gas and solid microemboli. Covariate analysis of pre- and post-operative functional magnetic resonance images was performed to correlate local mean signal intensity change with the extent of gas and solid microembolism. RESULTS: The median number of microemboli was 34 (range 10-176) in the off-pump group, 229 (range 127-314) in the on-pump CABG group, and 1220 (range 874-1261) in the open-heart group (P<0.05). The proportion of solid microemboli was significantly lower in the off-pump group in comparison to the on-pump CABG and open-heart groups (9 vs. 25 vs. 20%, respectively, P<0.01). Comparison of pre- and post-operative functional magnetic resonance images demonstrated an overall reduction in task-associated activation in the post-operative period. However, and paradoxically, in certain specific regions of interest there was an increase in the signal intensity which correlated with the total number of microemboli (r=0.9, P<0.01). CONCLUSIONS: Patients undergoing on-pump surgery have a higher degree of gas and solid microembolism which correlates with post-operative cerebral functional MRI activation. As activation with functional magnetic resonance imaging of the brain is known to be sensitive to a wide range of insults, it may prove to be a useful marker of perioperative cerebral injury that could help in the evaluation of potential cerebroprotective strategies.
BACKGROUND: Minimal access surgery (MAS) in small infants carries an important consideration. The tolerance of these small babies and the assumed physiological effect of MAS, in addition to the required anesthetic and surgical skills, have made it difficult to perform these types of procedures in many international centers. The present article reviews our experience with MAS in neonates and infants in the first year of life. METHODS: The medical records of all neonates and infants (<1 year) who underwent MAS over a period of 3 years were retrospectively reviewed for demographic information, procedures, operative time, complications, outcomes, and follow-up. Most of the operations were performed with 3-mm instruments and scopes and mean insufflation pressure of 10 mm Hg (range, 4-15 mm Hg). RESULT: Seventy neonates and infants were included in this study: 19 females and 51 males. The weight ranged from 1.3 to 8.2 kg (mean, 4.3 kg). The mean age was 93 days (range, 1 day to 12 months). Twenty-four (34%) were neonates (first 30 days of life). Procedures performed included repair of tracheoesophageal fistula, lobectomy, repair of diaphragmatic or hiatus hernias, pull-through for imperforated anus and Hirschsprung's disease, plication of the diaphragm, Kasai procedure, excision of choledochal cyst, pyloromyotomy, Ladd's procedure, and reduction of intussusceptions. There were 2 conversions, both in neonates with tracheoesophageal fistula. All patients tolerated the procedure very well, with lesser degrees in neonates undergoing thoracoscopic procedures. Two neonates had postoperative hypothermia (<35 degrees C) and 1 neonate had high PCO2 postoperatively. There was 1 mortality and no morbidities. The follow-up ranged from 1 month to 3 years (mean, 19 months). CONCLUSION: Minimal access surgery in neonates and infants is safe and well tolerated. Intraoperative monitoring of end-tidal CO2 and core temperature is essential in avoiding unwanted effects of performing these procedures, especially in neonates.
DTI seems to offer the possibility of adding important information to presurgical planning. Although experience is limited, DTI seems to provide useful local information about the structures near the tumor, and this seems to be useful in planning. In the future, DTI may provide an improved way to monitor intraoperative surgical procedures as well as their complications. Furthermore, evaluation of the response to treatment with chemotherapy and radiation therapy might also be possible. Although DTI has some limitations, its active investigation and further study are clearly warranted.
DTI seems to offer the possibility of adding important information to presurgical planning. Although experience is limited, DTI seems to provide useful local information about the structures near the tumor, and this seems to be useful in planning. In the future, DTI may provide an improved way to monitor intraoperative surgical procedures as well as their complications. Furthermore, evaluation of the response to treatment with chemotherapy and radiation therapy might also be possible. Although DTI has some limitations, its active investigation and further study are clearly warranted.
Surgeons are now performing much smaller, more directed parathyroid operations in less time, and reported cure rates are the highest they have ever been. The ability to operate physiologically,and not just anatomically, has allowed a more directed and confident approach. This approach has subsequently led to minimal use of anesthesia and to immediate postoperative discharge,changes that have been embraced enthusiastically by referring endocrinologists. This article discusses the intraoperative monitoring used by the author and the pitfalls that can await the inexperienced surgeon.
Despite the introduction of new medications, motor fluctuations and dyskinesias disable a significant proportion of Parkinson's disease patients. This has lead to renewed interest in stereotactic neurosurgery. A skilled team is needed to ensure that patient assessment and selection, operative technique, intraoperative monitoring, and post-operative management are optimised. High frequency stimulation has similar effects to ablative surgery, and is generally preferred. The clinical effects and possible mechanisms of action of deep brain stimulation of the subthalamic nucleus and globus pallidus are reviewed.
Explore the source record for details and available documents.
It cannot be overemphasized that a piece of electrical equipment is not capable of replacing a vigilant, well-trained clinician. As monitoring devices become more sophisticated, the potential for artifact or misinterpretation increases. When applied appropriately, operated properly, and interpreted correctly, however, the monitors afford the patient the best possible outcome.
Significant advances have been achieved in surgical and anesthetic techniques for the treatment of patients presenting with a variety of complex intrathoracic lesions. Despite the technologic advances, these patients continue to pose a challenge for anesthesiologists to provide safe and effective clinical care. A thorough understanding of the patient's underlying pathology inclusive of a detailed preoperative evaluation and effective communication between the surgical and anesthesia teams would help to ensure a favorable outcome.
BACKGROUND: Unresectable malignant liver tumors, particularly metastases of gastrointestinal origin, are rapidly lethal in a vast majority of patients, regardless of treatment. PATIENTS AND METHODS: We evaluated 58 patients by laparoscopy and/or laparotomy. Thirty-nine were treated with cryoablation of liver tumors using a liquid-nitrogen cryoprobe delivering a tumoricidal temperature of -196 degrees C with intraoperative ultrasound monitoring. Histologic evaluation showed that 25 patients had colorectal metastases, 3 had gastric tumors, 4 hepatocellular carcinomas, 6 carcinoids, and 1 gastrinoma. RESULTS: All patients who received complete cryoablation are alive with a mean follow-up of 14 months. Five whose treatment could not be completed died between 3 and 9 months postoperatively. Thirteen patients (28%) have recurrent disease and 20 (51%) have no evidence of disease. There were no operative mortalities. Postoperative transient elevation of liver function tests and thrombocytopenia were noted. All patients received postoperative chemotherapy. CONCLUSION: Cryoablation is an active and safe treatment for advanced liver malignancies.
BACKGROUND: Morbidity and mortality of emergency repair of type A dissecting aneurysms of the aorta are high. This is an attempt to investigate the risk determinants of early and late results. METHODS: A series of preoperative and operative variables were retrospectively collected from the clinical records of 291 patients operated on between January 1, 1979, and December 31, 1995. Risk factors for surgical death were investigated with univariate analysis and stepwise logistic regression. Follow-up was conducted between December 1995 and February 1996. Analysis of late results was conducted by means of actuarial survival curves (life method). After removing the surgical deaths, risk factors for late deaths were analyzed by a Cox model. RESULTS: The in-hospital mortality rate was 36.1%. Significant independent determinants of operative or early death were preoperative shock, preoperative neurologic impairment, operation before 1986, perioperative bleeding, and prolonged clamping time. The 10-year survival rate was 36.9% +/- 4.4%. Twenty-six patients required repeat operation. The long-term prognosis was significantly worse in patients who needed reoperation. CONCLUSIONS: Growing awareness of this disease and quicker diagnosis have increased the number of patients with acute dissection of the ascending aorta who are taken early to operation. This new challenge must be met by better preoperative support and intraoperative monitoring, and by surgical techniques that focus on lowering the rate of late complications, for which lifelong follow-up must be provided.