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PubMed1996

Methods for monitoring hemostasis during and following cardiac surgery.

The challenges in cardiac surgical hemostasis continue to plague the clinician. Rapid analysis and interpretation of coagulation tests are crucial in identifying coagulopathies that include both hemorrhagic and thrombophilic conditions. An understanding of the hemostatic mechanism, combined with a knowledge of pharmaceutical and transfusion interventions, is necessary to develop effective therapeutic plans. The coagulation tests that provide the most useful information include both end-point determinants and kinetic tests of clot formation. Future evaluation of the efficacy of coagulation tests in meeting these challenges will move beyond quantification of changes within various intermediates of hemostasis and rest with the correlation of these measured values with specific, outcome-directed indicators for optimizing patient care.

Blood Coagulation↗

PubMed1996

Monitoring hemostasis.

As our understanding of the normal mechanisms of coagulation grows, so does our ability to monitor hemostasis. Evaluation of hemostasis will become more specific and accurate and instrumentation techniques will become simpler and more efficient as technology progress, facilitating the monitoring of hemostasis in the perioperative setting.

Blood Coagulation↗

PubMed1997

The monitoring of mechanically ventilated patients.

Mechanical ventilation may adversely affect cardiovascular stability, pulmonary function, and airway anatomy. Hemodynamic monitoring needs to be adequate to determine the effects of mechanical ventilation on hemodynamic status in a given patient, effects that represent the complex interactions of airway pressure with venous return, right heart function, and left heart function. Monitoring of the adequacy of pulmonary gas exchange and intrinsic and extrinsic work of breathing can decrease adverse or inadequate effects of mechanical ventilation on respiratory function. Finally, monitoring cuff pressure will decrease the incidence of tracheal damage during mechanical ventilation.

Humans↗

PubMed1994

Brainstem auditory evoked potentials.

Brainstem auditory evoked potentials (BAEPs) have obtained widespread clinical application in assessing neurologic and audiologic problems. Seven waves (I-VII) are usually recorded in the first 10 ms following broad-band and high-intensity clicks. Latencies of waves I, III, and V, interpeak latencies of I-III, III-V, and I-V, and the amplitude ratio of wave V to wave I are common parameters evaluated for assessing clinically relevant abnormalities of BAEPs. Usually two-channel recordings are obtained: vertex (Cz) to ipsilateral ear and Cz to contralateral earlobe derivation. Evaluating different components in the two derivations helps their identification, particularly when the BAEPs are abnormal. Several technical and subject-related factors affect the amplitude and latencies of BAEP components besides lesions and dysfunctions involving the peripheral auditory structures and brainstem auditory pathways. BAEPs have maximal clinical utility in evaluating comatose patients, in patients with suspected demyelinating disorders, posterior fossa tumors, or in audiologic evaluation, especially in infants. They are also used for intraoperative monitoring of eighth-nerve and brainstem function during different types of posterior fossa surgery.

Brain Stem↗

PubMed2000

Early arytenoid adduction for vagal paralysis after skull base surgery.

OBJECTIVES: To evaluate the efficacy of early arytenoid adduction in the management of vagal paralysis after skull base surgery. STUDY DESIGN: Retrospective evaluation at a tertiary care skull base center. METHODS: Aggressive surgical management of skull base lesions has become increasingly popular owing to advances in surgical technique and intraoperative monitoring. Temporary and permanent lower cranial neuropathies occur frequently, especially after the surgical management of lesions involving the vertebrobasilar system and the jugular foramen. An injury to the proximal vagus nerve is usually associated with dysphonia and swallowing dysfunction. An early arytenoid adduction has been employed in 26 patients with a vagal paralysis after skull base surgery. Most commonly, the neurosurgical patient underwent an arytenoid adduction under general anesthesia on postoperative day 2. RESULTS: Videostroboscopy after arytenoid adduction demonstrated 76% of patients had complete glottic closure. Of those with inadequate glottic closure, all demonstrated a well-medialized posterior glottis with a persistent anterior glottal gap. These patients were easily treated with a secondary type I thyroplasty under local anesthesia with sedation resulting in complete glottic closure. Despite excellent voice outcomes, 66% of these patients had dysphagia requiring enteral feedings for nutritional support. CONCLUSIONS: An early arytenoid adduction is an excellent medialization technique that can be performed safely in the early postoperative period under general anesthesia after skull base surgery.

Anesthesia, General↗

PubMed1991

Herniated L4-L5 disc after placement of Harrington instrumentation for a fracture of the thoracolumbar spine.

The authors report a case in which L5 radiculopathy developed acutely after surgery for placement of Harrington rod instrumentation for an L1 body fracture. Computed tomographic myelography demonstrated a large L4-L5 herniated disc that had not been present in preoperative studies. An emergency laminectomy was performed, and a large, free, subligamentous disc fragment was removed. The patient subsequently regained L5 sensorimotor function. The postoperative development of lumbar radiculopathy is an uncommon complication of Harrington rod instrumentation that may result from several biomechanical features of the instrumentation. These injuries may not be detected by intraoperative monitoring of somatosensory evoked potentials, and therefore, the postoperative neurological examination assumes a crucial role in the early diagnosis of these lesions. As our case demonstrates, these radicular deficits may be reversible if their cause is promptly recognized and treated.

Aged↗

PubMed1991

Effects of nitrous oxide on motor evoked potentials recorded from skeletal muscle in patients under total anesthesia with intravenously administered propofol.

The effect of nitrous oxide (N2O) on motor evoked potentials (MEPs) recorded from human subjects under total intravenous anesthesia with propofol (2,6-diisopropylphenol) was studied. MEPs were recorded from the 1st dorsal interosseous muscle of the foot in nine subjects; in two of these, simultaneous recordings were made from the 2nd dorsal interosseous muscle of the hand and from the deltoid muscle. Single transcranial electrical stimuli were used in recording the MEPs. The effects of N2O were studied at concentrations from 20 to 70%. Increasing concentrations of N2O caused a progressive increase in onset latency and a fall in the peak-to-peak amplitude of the MEPs recorded from the foot. Latency values showed a significant increase above the baseline at concentrations of N2O greater than 20% (P values, 0.05-0.005). The response amplitude showed a significant decrease from the baseline at concentrations of N2O greater than 50% (P values, 0.05-0.005). The 2nd dorsal interosseous muscle of the hand demonstrated a pattern of sensitivity to N2O similar to that of the 1st dorsal interosseous muscle of the foot. The onset latency and initial peak-to-peak amplitude of the deltoid muscle were insensitive to N2O at the concentrations used. We conclude that N2O can be used as an anesthetic adjunct without a significant deleterious effect on MEPs during intraoperative monitoring in patients under propofol anesthesia, providing concentrations are maintained below 50%.

Adult↗

PubMed1997

Management of vestibular schwannomas (acoustic neuromas): the value of neurophysiology for evaluation and prediction of auditory function in 420 cases.

OBJECTIVE: From 1978 to 1993, 1000 vestibular schwannomas were operated on at the Department of Neurosurgery at Nordstadt Hospital. The goal was to improve the chances of hearing preservation by recording auditory brain stem responses (ABRs). ABRs can be used for preoperative classification of cochlear nerve impairment and for prediction of the chances of hearing preservation. PATIENTS AND METHODS: In addition to the previously described audiometric testing, the patients underwent perioperative and intraoperative bilateral ABR recording at 100-dB condensation and rarefaction click stimulation. The classification system of five types of ABRs, as presented before, is based on the presence and on the latencies of Waves I, III, and V, with a special emphasis on Wave III's representing the activity of the first brain stem nuclei within the auditory pathway. According to an analysis of 420 preoperative ABRs, in case of a preoperative Type 1 or 2, the rate of hearing preservation is 80%. DISCUSSION: In the case of good clinical and audiometric hearing, a severely deteriorated ABR is mostly an indicator of severe nerve compression and adhesion by the tumor. In view of subsequently reported experiences with intraoperative ABR monitoring, the value of the presented system emphasizing the importance of Wave III is stressed and discussed with other views in the literature. The criteria presented here are not designed for recognition of retrocochlear disease but aim for evaluation of the state of the auditory nerve and its perspective. CONCLUSION: By the presented classification of ABR Type B1 through B5, preoperative prediction of the likelihood of hearing preservation is improved.

Adult↗

PubMed2002

Is the root entry/exit zone important in microvascular compression syndromes?

OBJECTIVE: Microvascular compression syndromes such as trigeminal neuralgia, hemifacial spasm, and disabling positional vertigo involve an artery or vein compressing a cranial nerve. A cranial nerve is composed of a central nervous system (CNS) segment and a peripheral nervous system (PNS) segment separated by the root entry/exit zone (REZ). Although vascular compression can occur at any point along the cranial nerve, it has been generally assumed that only vascular contact at the REZ of the affected cranial nerve can cause symptoms. On the basis of personal surgical experience, we propose that vascular compression of the CNS segment alone causes symptoms. This has important repercussions for the future diagnosis and treatment of microvascular compression syndromes, especially the cochleovestibular compression syndrome. METHODS: For the anatomic study, four autopsy specimens and one surgical biopsy specimen of the vestibulocochlear nerve were microscopically and ultramicroscopically analyzed for structural differences between the CNS and PNS segments. For the clinical study, five patients with the clinical picture of cochleovestibular compression syndrome were treated by microsurgical decompression at the level of the CNS segment and not the REZ. One patient underwent reoperation for recurrent symptoms 4 years later, and a 4-mm vestibular neurectomy was performed at that stage. We performed an epidemiological analysis to demonstrate that the known incidences of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are related to the length of their respective CNS segments. RESULTS: Histological differences between the PNS and CNS segments suggest that the PNS segment is more resistant to compression. This was confirmed by neurophysiological data from intraoperative monitoring in posterior fossa surgery and experimental studies. We found a clear epidemiological correlation between the length of the CNS segment, which differed among cranial nerves, and the incidence of the microvascular compression syndrome. Successful decompression of the CNS segment in patients without compression at the REZ of the vestibulocochlear nerve for disabling positional vertigo provides clinical support for this hypothesis. CONCLUSION: The evidence we present supports the hypothesis that vascular compression syndromes arise from vascular contact along the CNS segment of the cranial nerves.

Blood Vessels↗

PubMed1997

The "triple technique" for treating stable Graves' ophthalmopathy.

Graves' ophthalmopathy may range from mild eyelid retraction to a devastating process that involves the entire orbit and culminates in gross ocular congestion, massive proptosis, and even blindness. Whether the ophthalmopathy is mild or severe, patients are managed on an individual basis according to the predominant clinical findings, which may include congestion, myopathy, lid retraction, proptosis, and optic neuropathy. The process usually becomes quiescent after 6 months to 3 years; however, the changes caused by fibrosis (lid retraction and ocular muscle enlargement) are permanent. The cornerstone of surgical treatment for severe cases is bony orbital decompression; however, in our experience, mild to moderate Graves' ophthalmopathy is better treated by combining eyelid surgery and orbital lipectomy. Our approach consists of a conservative orbital lipectomy, the lengthening of the levator-Müller complex by means of marginal myotomies, and a limited lateral tarsal apposition. These three different surgical steps, which have been described previously as isolated procedures, are undertaken on both eyes at the same time and modulated according to the deformity of the patient. The operation can be performed under local anesthesia with sedation, thus allowing intraoperative monitoring of the correction; the patient can be discharged after a few hours. The results in 32 operated eyes of 16 patients have been a marked aesthetic and functional improvement, with no complications after 6 to 18 months of follow-up. The relative simplicity and very low morbidity of this procedure, as well as its reliability, make it ideal in patients with mild to moderate aesthetic and functional impairment who are looking for a substantial improvement but are unwilling to undergo a relatively major procedure such as a transosseous decompression, which, in our opinion, is the operation of choice only when the patient presents with optic neuropathy or major proptosis.

Adult↗

PubMed1976

The perioperative management of pericardial tamponade.

A case report of a patient with acute pericardial tamponade is presented. The etiology, pathophysiology, and management of cardiac tamponade is discussed. Preoperative management includes volume expansion, administration of catecholamines, and pericardiocentesis. Intraoperatively, monitoring should include continuous measurement of arterial and central venous pressures. Ketamine has been found to be very useful in these patients.

Anesthesia, General↗

PubMed1997

Sedation and anesthesia for pediatric bronchoscopy.

Bronchoscopic examination may be indicated to evaluate various parts of the airway including the larynx, the subglottic region, or the more peripheral aspects of the tracheobronchial tree. The chances of a successful examination may be increased by the appropriate use of sedation. The following article reviews the steps required prior to during, and after the provision of anesthesia for bronchoscopic examination of the airway. The essentials of the preoperative examination, requirements for intraoperative monitoring, and postoperative recovery are discussed. The various agents and techniques available for deep sedation and general anesthesia are reviewed.

Analgesics↗

PubMed1990

The equivalence of anesthetic regimens with respect to plasma glucose elevation during cerebrovascular surgery.

Hyperglycemia, even if mild, is known to aggravate neuronal damage from cerebral ischemia. In order better to define the influence of currently used anesthetic techniques on plasma glucose levels during cerebrovascular surgery, we examined serial plasma glucose values during 43 carotid endarterectomies (CEA) and 19 intracranial arteriovenous malformation (AVM) resections. CEA patients (aged 67.6 +/- 1.4 years and weighing 76.4 +/- 2.3 kg, mean +/- SEM) received N2O in O2 and either isoflurane (ISO) (n = 14), halothane (n = 8), fentanyl (n = 10), or sufentanil (n = 11). Plasma glucose was compared at 1.12 +/- 0.05 h (stage 1), 2.08 +/- 0.07 h (stage 2), and 3.12 +/- 0.1 h (stage 3) after induction of anesthesia. AVM patients received ISO and N2O in O2. Plasma glucose was compared 2.32 +/- 0.14 h (stage 1) and 6.25 +/- 0.34 h (stage 2) after induction of anesthesia (surgical stage). Glucose was determined by the hexokinase method. In the CEA cases, progressively elevated plasma glucose levels were associated with successive surgical stage (114 +/- 6, 122 +/- 6, and 138 +/- 6 mg/dl). The seven CEA patients that carried the diagnosis of diabetes mellitus tended to have higher glucose levels but they did not differ significantly from nondiabetic patients. The AVM patients (aged 35.7 +/- 2.3 years and weighing 71.1 +/- 2.9 kg) were all nondiabetic. They were significantly younger than the CEA patients and each received dexamethasone intraoperatively. In these patients, there was a significant effect (p <0.04) of surgical stage to increase plasma glucose (115 +/- 10 vs. 126 +/- 10 mg/dl). For CEA, the anesthetic techniques examined do not differ significantly in their influence on plasma glucose levels, but all techniques were associated with a gradual increase in plasma glucose levels intraoperatively, even in nondiabetic patients. Compared to the group of younger AVM patients, glucose elevation was more pronounced in the elderly CEA patients. We conclude that intraoperative monitoring of plasma glucose may be useful in elderly patients during prolonged neurovascular procedures.

Journal Article↗

PubMed2001

Dexmedetomidine infusion and somatosensory evoked potentials.

Intraoperative neurophysiologic monitoring requires information on the effects of anesthetic drugs because these drugs can directly alter evoked potentials, thus interfering with monitoring. We report on our evaluation of the effect of the recently introduced alpha2-adrenergic agonist, dexmedetomidine, on the somatosensory evoked potentials in two patients undergoing cervico-occipital fusion. Our results suggest that, although dexmedetomidine can affect the later cortical peaks of somatosensory evoked potentials (SSEPs), consistent and reproducible potentials can be recorded.

Adrenergic alpha-Agonists↗

PubMed2005

Surgical outcome of ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine: implication of the type of ossification and surgical options.

OBJECTIVE: Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine produces myelopathy through anterior spinal cord compression that is usually progressive and unaffected by conservative treatment. Therefore, early decompressive surgery is imperative. However, decompression surgery of thoracic myelopathy is difficult, and the outcome is often poor. A retrospective study was conducted to investigate the surgical outcome of 21 patients with thoracic OPLL to evaluate which type of surgical approach is better and which type of thoracic OPLL results in a better surgical outcome. METHODS: A total of 21 patients with thoracic OPLL (10 men and 11 women; mean age 54 years), who underwent surgical treatment at our department from March 1985 to October 2000, were included in the study. Seven patients exhibited the flat-type OPLL and underwent either anterior decompression and fusion (one patient), anterior decompression via a posterior approach (three patients), or expansive laminoplasty (three patients). Fourteen patients exhibited the beak-type OPLL and also underwent either anterior decompression and fusion (two patients), anterior decompression via a posterior approach (six patients), or expansive laminoplasty (six patients). RESULTS: Regarding of operative time and blood loss, there were no marked differences between the two types of OPLL, regardless of the type of surgical procedure; anterior decompression and fusion and anterior decompression via a posterior approach yielded longer operative times and larger blood loss volumes than expansive laminoplasty. Concerning clinical outcome, there were five cases of neurologic deterioration. All of the five deteriorated cases were of the beak-type OPLL treated by a posterior approach. Two of these patients were treated with expansive laminoplasty. CONCLUSIONS: There were five instances of neurologic deterioration in our thoracic OPLL series, and all of them exhibited beak-type OPLL. In the beak-type OPLL, a subtle alteration in the spinal alignment during posterior decompression procedures may increase spinal cord compression, leading to the deterioration of symptoms. A potential increase in kyphosis following laminectomy should be avoided by fixation with a temporary rod. If intraoperative monitoring suggests spinal cord dysfunction, an anterior decompression procedure should be attempted as soon as possible.

Decompression, Surgical↗

PubMed2003

Use of ultrasound guidance in the insertion of radial artery catheters.

OBJECTIVE: To assess the role of a portable ultrasound device in the insertion of radial artery catheters. DESIGN: Prospective, randomized, comparative study. SETTING: Tertiary university hospital. PATIENTS: Elective surgery patients requiring arterial catheter insertion for intraoperative monitoring. INTERVENTIONS: A portable ultrasound device was used to visualize the radial artery at the wrist and to direct arterial catheter insertion. This new technique of arterial catheter insertion was compared with the classic palpation technique. MEASUREMENTS AND MAIN RESULTS: A total of 69 patients requiring an arterial catheter were randomized to either the ultrasound (34 patients) or palpation technique (35 patients). The time taken from skin puncture to successful arterial catheter insertion, the time taken per insertion attempt, the number of attempts required, and the number of cannulae used were recorded for each group. The arterial cannula was inserted on the first attempt in 21 (62%) cases using ultrasound vs. 12 (34%) cases by palpation (p =.03). Significantly fewer attempts were required for catheter insertion using ultrasound as compared with palpation (mean +/- sd, 1.6 +/- 1.0 vs. 3.1 +/- 2.4; p=.003); however, the time taken for each successful attempt was longer (26.1 +/- 2.0 vs. 17.3 +/- 1.6 secs, p=.001). A trend toward shorter overall time required for catheter insertion was found for the ultrasound group (55.5 +/- 63.8 vs. 111.5 +/- 121.5 secs, p=.17). There were four failures in the ultrasound group and one in the palpation group (not significant). CONCLUSIONS: Ultrasound is a useful adjunct to arterial catheter insertion and increases the rate of success at first attempt. The technique is easy to learn and may reduce the time taken to insert the catheter.

Aged↗

PubMed2006

Controversies in building a management algorithm for vestibular schwannomas.

PURPOSE OF REVIEW: The present review examines the various mainstream treatment options, benefits and risks, and controversies involved in developing a management algorithm for treatment of vestibular schwannoma. RECENT FINDINGS: Advances in microsurgery and radiosurgery have made tremendous contributions to management of vestibular schwannoma; however, considerable controversy still exists. The auditory and facial nerve functional outcomes have improved with use of intraoperative monitoring for vestibular schwannoma removal and with lower radiosurgery doses; however, risks to the facial and auditory nerves still exist. Observing vestibular schwannomas for growth with serial magnetic resonance imaging is an increasingly popular option for small vestibular schwannomas that allows patients to enjoy hearing and facial function. SUMMARY: The risks and benefits of each treatment option must be weighed for each patient, and management decisions regarding vestibular schwannomas should be individualized for each patient depending on tumor anatomy, patient preferences, and symptoms.

Algorithms↗

PubMed2003

Esophageal Doppler: noninvasive cardiac output monitor.

In this article we describe the esophageal Doppler, a noninvasive, instantaneous cardiac output monitor. Its reliability has been demonstrated to be comparable to that of other current techniques used in the clinical arena to measure cardiac output. It helps guiding intravascular fluid resuscitation by quantifying the increase in flow in response to fluid challenges and by indicating the plateau of the patient's cardiac function curve. When the plateau has been reached, further fluid loading may result in congestion without improvement in systemic flow. Thus, measuring cardiac output is the only way to determine the upper limit for fluid intake. In addition, a strategy based on cardiac output optimization has proven beneficial in high-risk surgical patients.

Cardiac Output↗