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PubMed1994

Pure opioid versus opioid-volatile anesthesia for coronary artery bypass graft surgery: a prospective, randomized, double-blind study.

This study was designed to assess, in a prospective, randomized, blinded fashion, the hemodynamic effects of different anesthetics used in the prebypass period during coronary artery bypass grafting (CABG) and the effect on incidence of ischemia. Seventy-five patients were randomly assigned to receive sufentanil increments, isoflurane, or enflurane after a standard premedication and anesthetic induction with sufentanil 5 micrograms/kg. Myocardial ischemia was monitored intraoperatively by the anesthesiologist with electrocardiogram (ECG) leads V5(CB5) and II, and by a Holter monitor of the same leads from which recordings were analyzed postoperatively by a cardiologist. A continuous recording of the blood pressure was analyzed to determine the duration of hypertensive responses. Arterial blood pressure control was best in the patients supplemented with anesthetic vapors; patients receiving beta-adrenergic blockers or those receiving isoflurane were less likely to require treatment for tachycardia. All episodes of myocardial ischemia occurred within 5 min of induction-intubation and were diagnosed more frequently by the anesthesiologist than on the Holter monitor (29% vs 9%), with no difference between groups. There were five perioperative myocardial infarctions with no difference between groups. After anesthetic induction with sufentanil 5 micrograms/kg, isoflurane or enflurane given during CABG provides better hemodynamic control than increments of sufentanil and is associated with a similar incidence of prebypass ischemia and perioperative infarction.

Coronary Artery Bypass↗
PubMed1986

An assessment of intrarenal hydrostatic pressure measurements in the diagnosis of acute renal allograft rejection.

Postoperative intrarenal pressure measurements may be an aid to the diagnosis of acute renal transplant rejection, especially in patients treated with cyclosporine. Serial measurements of intrarenal pressure were made in 38 recipients using a fine-needle technique. Thirty-two intraoperative and 207 postoperative measurements were made, and 39 clinical rejection episodes (23 confirmed by biopsy) monitored. Intraoperative pressures in grafts with immediate function (37.4 +/- 4.0 mmHg, mean +/- SEM) were not significantly different from those with delayed function (30.9 +/- 4.8 mmHg), whereas postoperative pressures were greater (P less than 0.01) in kidneys with acute tubular necrosis (29.4 +/- 1.9 mmHg) than in functioning grafts (20.4 +/- 0.9 mmHg). Pressures recorded during clinical rejection episodes (44.3 +/- 2.3 mmHg) exceeded (P less than 0.001) those during quiescent periods (23.6 +/- 1.0 mmHg). During rejection episodes, higher pressures (P less than 0.01) were recorded from tender or palpably enlarged grafts (52.5 +/- 3.0 mmHg) than in the absence of these signs (36.3 +/- 3.1 mmHg), and patients whose transplants biopsies showed cellular rejection tended to have greater pressures (50.1 +/- 4.1 mmHg) than those with concomitant vasculopathy (36.4 +/- 3.9 mmHg), but the latter did not reach statistical significance. In 7 cases of cyclosporine toxicity the intrarenal pressure was 17.8 +/- 4.2 mmHg. Using a diagnostic cut off point of 40 mmHg, the investigation failed to recognize 26% of acute rejection episodes--and, in the presence of acute tubular necrosis, it wrongly categorized 21% of nonrejectors. While its predictive capacity was limited, the test may occasionally be helpful in the differentiation of cyclosporine toxicity and rejection in functioning kidneys.

Acute Kidney Injury↗
PubMed2006

Evaluation of cellophane banding with and without intraoperative attenuation for treatment of congenital extrahepatic portosystemic shunts in dogs.

OBJECTIVE: To evaluate the effect of intraoperative attenuation of congenital extrahepatic portosystemic shunts (CEPSSs) during cellophane banding procedures in dogs. STUDY DESIGN: Retrospective case series and prospective study. ANIMALS: 18 cases evaluated retrospectively and 14 dogs evaluated prospectively. PROCEDURES: Gradual occlusion of CEPSSs was performed via cellophane banding. Shunts were occluded to a diameter < 3.0 mm during surgery in dogs prospectively enrolled in the partial attenuation group, whereas the shunt was not attenuated during surgery in dogs prospectively enrolled in the no-attenuation group or in dogs that had previously undergone surgery and were retrospectively evaluated. Postprandial serum bile acids (PPSBA) concentrations were measured before surgery and at various time points after surgery. RESULTS: Mean +/- SD PPSBA concentrations were 26.8 +/- 24.5 micromol/L at < 2.25 months after surgery (n = 16 dogs), 22.1 +/- 14.0 micromol/L from 2.25 to 6 months after surgery (12 dogs), and 34.9 +/- 32.5 micromol/L at > 6 months after surgery (22 dogs). In the prospectively enrolled dogs, mean PPSBA concentrations increased over time in dogs in the partial attenuation group, but not in dogs in the no-attenuation group. CONCLUSIONS AND CLINICAL RELEVANCE: Cellophane banding may be used to occlude larger CEPSSs and may decrease the need for intraoperative monitoring of portal vein blood pressure. The technique may facilitate minimally invasive treatment of CEPSSs in dogs. Intraoperative attenuation of CEPSSs to a diameter < 3.0 mm is not necessary and may result in a less favorable outcome.

Animals↗
PubMed2006

False negative in spinal cord monitoring using spinal cord-evoked potentials following spinal cord stimulation during surgery for thoracic OPLL and OLF.

Several electrophysiologic methods have been used for intraoperative monitoring of spinal cord functions. Recently, muscle responses following transcranial electric stimulation have also been widely used. However, in patients with severe myelopathy, only the spinal cord responses following spinal cord stimulation can be recorded. We report a false-negative case in monitoring using spinal cord responses following spinal cord stimulation. The patient presented with severe thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL) and ligamentum flavum. Spinal cord responses following spinal cord stimulation were recorded during laminectomy and partial removal of the OPLL. Although the amplitude of those responses decreased transiently to within 50% of control data during decompression, it had recovered to the control level by the end of surgery. Just after surgery, the patient showed complete motor paralysis with preserved sensory function. Spinal cord responses following spinal cord stimulation can be recorded in patients with severe myelopathy. However, motor problems may occur when surgery is continued in the false belief that responses are accurate.

Electric Stimulation↗
PubMed1989

Influence of anesthetics--nitrous oxide in particular--on electromyographic response evoked by transcranial electrical stimulation of the cortex.

The influence of anesthetics usually used for neuroleptic anesthesia--nitrous oxide, fetanyl, flunitrazepam, and thiopental sodium--on motor evoked potentials (MEP) was examined in 15 patients during neurosurgical operations on the spinal cord, in 16 patients in traumatic coma, and in 6 healthy volunteers. MEP were recorded from the contralateral thenar and anterior tibial muscles in response to single transcranial electrical stimuli on the motor cortex. Intraoperatively, during neuroleptic anesthesia we found the amplitudes to be reduced to an average of 11% of the preoperative baselines for the thenar potentials, and to 7% of the preoperative baselines for the anterior tibial muscle potentials, despite a maximum stimulus strength of 750 V. A similar reduction of MEP amplitudes was observed in 6 volunteers during breathing of an oxygen/nitrous oxide mixture (34%/66%), whereas fentanyl, flunitrazepam, and thiopental had only a minor effect on MEP. We conclude that with respect to anesthesia-related suppression of amplitudes, an average of 5 to 15 electromyographic responses should be evaluated for intraoperative monitoring of MEP using the technique described here.

Adult↗
PubMed2006

Interpretation of intraoperative parathyroid hormone monitoring in patients with baseline parathyroid hormone levels of <100 pg/mL.

BACKGROUND: Common guidelines for intraoperative parathyroid hormone (IOPTH) interpretation are based on clearly elevated baseline parathyroid hormone (PTH) values. We hypothesize that patients with low-baseline levels (<100 pg/mL) have a higher incidence of multigland disease (MGD) and display differences in PTH kinetics compared with patients with high-baseline levels. METHODS: We retrospectively reviewed the cases of 1151 patients with primary hyperparathyroidism who underwent parathyroidectomy with IOPTH monitoring. Of these, 141 patients had low-baseline values. Multiple comparisons were made between the low-baseline and high-baseline groups. RESULTS: Twenty-six percent of the low-baseline patients had MGD versus 15% of the high-baseline patients (P = .002). The PTH kinetics differed between groups after gland excision at both 5 and 10 minutes. Adherence solely to the "50% rule" during minimally invasive parathyroidectomy potentially would have missed 25% of patients with MGD in the low-baseline group versus 10% in the high-baseline group; 5.7% of the low-baseline patients had persistent or recurrent hypercalcemia versus 2.9% of the high-baseline patients. CONCLUSION: MGD is significantly more prevalent among low-baseline patients, and PTH kinetics are somewhat different between groups. The current guidelines that are used for IOPTH monitoring may not be ideal for use in this low-baseline group and will likely need to be revised after further study of this group of patients.

Diagnosis, Differential↗
PubMed1982

The wake-up technique as a dual protector of spinal cord function during spine fusion.

Intraoperative awakening is commonly used to evaluate voluntary motor function to lessen the risks of nerve damage during posterior spine fusion and Harrington rod instrumentation for idiopathic scoliosis. This is a report of intraoperative monitoring of tension in the soft tissues of patients with idiopathic scoliosis utilizing a strain-gauged distraction outrigger. The tension in soft tissues was found to drop following intraoperative awakening by an average of 52 N in the 14 patients monitored. The "wake-up" technique may aid in protecting the spinal cord from overdistraction by the increase in soft tissue tension present at the time of Harrington rod replacement in addition to providing a spot check of motor function. This increased tension may slightly repress curve correction.

Anesthesia, Inhalation↗
PubMed2004

Evaluation of intraoperative recurrent nerve monitoring in thyroid surgery.

Surgical exposure of the recurrent laryngeal nerve decreases the incidence of nerve injuries during thyroid surgery. Intraoperative neuromonitoring was introduced to facilitate identification and protection of the recurrent laryngeal nerve. Between February 1996 and June 2002 a total of 288 patients underwent thyroid surgery with intraoperative identification and intraoperative neuromonitoring of the recurrent laryngeal nerve. The overall incidences of permanent and transient recurrent nerve palsy (considered as a percentage of the nerves at risk) were 1.4% and 8.7%, respectively. Results were stratified in benign, malignant, and recurrent thyroid disease. Intraoperative function testing revealed a positive predictive value of 33% and negative predictive value of 99%. We concluded that the incidence of recurrent nerve lesions in benign, malignant, and recurrent thyroid disease was not lowered by the use of intraoperative neuromonitoring. Although an intact nerve can be verified by the neuromonitoring, the loss of nerve function cannot be reliably identified.

Adolescent↗
PubMed2004

Focused cervical exploration for primary hyperparathyroidism without intraoperative parathyroid hormone monitoring or use of the gamma probe.

Selected patients with primary hyperparathyroidism (pHPT) who have a positive preoperative sestamibi scan can be managed safely and successfully with a focused cervical exploration without either adjuvant intraoperative parathyroid hormone (PTH) monitoring or use of a gamma probe. This article reports a retrospective analysis of a consecutive series of patients surgically treated at a tertiary referral center. From August 1998 to August 2002, 100 patients (68 women, 32 men; mean age 63 years [range: 29-89 years]) underwent a focused cervical approach without intraoperative PTH monitoring or use of the gamma probe after perioperative sestamibi injection. The study group comprised 9% of all patients (n = 1063) undergoing cervical exploration for pHPT during the study period. Ninety patients underwent an initial exploration, and 10 others underwent repeat cervical exploration following prior parathyroid (n = 7) or thyroid (n = 3) operation. Sestamibi scanning correlated with one enlarged parathyroid gland in all patients. Other enlarged glands were, however, not demonstrated in three patients (true positive = 97%; false negative = 3%). The single enlarged glands excised in all patients had a mean weight of 795 mg (range: 90-3640) and were histologically compatible with an adenoma. Postoperatively, 97% of patients were eucalcemic. Three patients remained hypercalcemic (3%). Of the three patients with persistent hypercalcemia, one underwent successful re-exploration with excision of a 500 mg second adenoma, whereas the other two patients (with confirmed familial HPT) remained hypercalcemic. Mean hospitalization was 0.5 days (range: 0-3 days). There was no operative mortality. No patients had permanent hypocalcemia. Postoperative morbidity occurred in three patients: two self-limiting cervical hematomas and one permanent vocal cord paralysis. Selected patients with pHPT due to single-gland disease and an unequivocally positive preoperative sestamibi scan can safely and successfully be managed with a focused unilateral cervical exploration without either intraoperative PTH monitoring or use of the gamma probe. Further experience with this surgical approach seems warranted to determine the overall cure rate, operative morbidity, and the sensitivity and specificity of preoperative localization studies.

Adenoma↗
PubMed2003

Awareness during surgery.

OBJECTIVE: Patients who experience awareness under surgery may suffer from the post-traumatic stress disorder with its long-lasting psychological damage. Furthermore, there are also media attention and legal consequences. In spite of understanding its causes, it is still occurring worldwide and there are no reports of awareness in the Saudi medical literature. This prospective study was conducted to determine the incidence of awareness when its causes are eliminated and to record patient satisfaction. METHODS: Surgical patients >4 years old (ASA I-III) admitted to the Armed Forces Hospital, Wadi Al-Dawasir, Kingdom of Saudi Arabia, between October 1998 and November 2002 were included in the study. Patients were given a premedicant with an amnesic effect. Anesthetic equipment with a built-in end-tidal anesthetic gas monitor was checked preoperatively. Minimal anesthetic concentrations of vapors were delivered and monitored. Intraoperative analgesia was provided whenever appropriate. Patients were closely observed for signs of intraoperative awareness under general anesthesia. All patients were interviewed within 24 hours postoperatively on the occurrence of awareness and service satisfaction. RESULTS: There were 4368 patients admitted to the study. Their ages ranged from 14-104 years (mean 40.2 years). All patients were interviewed in the postoperative period. There was no report of awareness during surgery and patient satisfaction score was 100%. CONCLUSION: Preoperative and intraoperative anesthetic attention to patients presented for surgery, together with the use of modern anesthetic delivery units possessing facilities for monitoring anesthetic gases, and the provision of good analgesia are the most important combination in eliminating awareness during surgery.

Adolescent↗
PubMed1982

Intraoperative detection of spinal cord ischemia using somatosensory cortical evoked potentials during thoracic aortic occlusion.

Paraplegia remains a devastating and unpredictable complication of surgical procedures requiring temporary occlusion of the thoracic aorta, interruption of important spinal radicular vessels, or both. Intraoperative monitoring of the physiological integrity of the spinal cord should permit the early detection of spinal cord ischemia, the judicious and timely institution of corrective measures, including bypass or shunting, and the preservation of important intercostal arteries in appropriate circumstances. A model of spinal cord ischemia was created by temporary proximal and distal occlusion of the canine thoracic aorta. Serial measurement of somatosensory cortical evoked potentials (SCEP) generated by peripheral nerve stimulation, reflecting the status of long-tract neural conduction, was used to monitor alterations in spinal cord function during ischemia. Twelve animals subjected to aortic occlusion demonstrated a characteristic time-related deterioration of the SCEP with virtual extinction of the signal at a mean interval (+/- standard error of the mean) of 12.4 +/- 1.5 minutes. Six animals in which reperfusion was established immediately following the loss of the SCEP (Group 1) demonstrated complete recovery without neurological sequelae, as assessed by clinical and histological criteria. In 6 animals (Group 2), the period of aortic occlusion was extended for an additional 15 minutes following loss of the SCEP (27.3 +/- 2.3 minutes); postoperatively, 4 of 6 animals sustained major neurological lesions characterized by spastic paraplegia and histological evidence of spinal cord infarction (Group 1 versus Group 2, p less than 0.05). We conclude that distinctive alterations in the SCEP are indicative of reversible ischemic spinal cord dysfunction. On-line monitoring of spinal cord function using the technique of SCEP provides a rational basis for determining of SCEP provides a rational basis for determining operative strategy during surgical procedures on the thoracic aorta.

Animals↗
PubMed2002

Survey of the members of the cardiovascular section of the Canadian Anesthesiologists' Society on the use of perioperative transesophageal echocardiography - a brief report.

PURPOSE: Transesophageal echocardiography (TEE) is a useful diagnostic and monitoring tool in the operating room. In the United States, an increasing number of centres are training anesthesiologists to preform intraoperative TEE. In Canada, TEE has been slow to gain acceptance as an intraoperative monitor and little information is available on its use by the anesthesiologists across the country. METHODS: We surveyed all members of the cardiovascular section of the Canadian Anesthesiologists' Society, to find out how many perform TEE, how they acquired their skills and how they use TEE in their practice. RESULTS: The response rate was 48.4%. Most respondents were Canadian-trained cardiac anesthesiologists working in university centres. 91% of respondents stated that their centres offer intraoperative TEE services. Of those services, 35.1% were provided by anesthesiologists only, 13% by cardiologists only, and 51.9% by both. 53.8% of respondents have certification in intraoperative TEE (NBE/SCA, ASE or Provincial College). 90% of respondents use equipment that is less than five years old and multiplane probes are used by almost everyone. There was strong support for Canadian-based continuing medical education events in perioperative TEE. CONCLUSION: TEE appears to be available in most cardiac centres in Canada and anesthesiologists are actively involved in providing intraoperative TEE services, using state-of-the-art equipment. Many anesthesiologists have formal training in TEE.

Anesthesiology↗
PubMed2007

Minimally invasive parathyroidectomy without intraoperative parathyroid hormone monitoring in patients with primary hyperparathyroidism.

BACKGROUND: Minimally invasive parathyroidectomy (MIP) is the preferred operation for patients with primary hyperparathyroidism (HPT) and positive preoperative imaging. This non-randomized case series assessed the long-term results of MIP performed without the use of intraoperative parathyroid hormone (ioPTH) monitoring. METHODS: The study involved prospective collection of demographic, biochemical and operative details on a consecutive, unselected cohort of 298 patients who underwent surgery for non-familial primary HPT during a 5-year interval. The mean preoperative serum calcium level was 3.00 mmol/l with a mean parathyroid hormone concentration of 25.8 pmol/l. (99m)Tc-labelled sestamibi scanning and neck ultrasonography were performed in 262 patients. RESULTS: Sestamibi scan showed unilateral uptake in 182 patients and a single parathyroid adenoma was confirmed on ultrasonography in 161 patients. MIP was performed in 150 patients. The mean duration of operation was 25 (range 8-65) min. Four patients needed conversion to conventional neck exploration. There was one postoperative haematoma and three cases of temporary recurrent laryngeal nerve neuropraxia. All but four patients were normocalcaemic after MIP. All the parathyroid tumours removed were adenomas, with a mean weight of 1.3 (range 0.1-17.4) g. No patient developed recurrent HPT after a median follow-up of 16 (range 3-48) months. CONCLUSION: The outcome of MIP without ioPTH monitoring was comparable to that reported in series that used ioPTH monitoring.

Adolescent↗
PubMed1989

Vestibulospinal evoked potential versus motor evoked potential monitoring in experimental spinal cord injuries of cats.

Changes in vestibulospinal evoked potentials (VsEP) and motor evoked potentials (MEP) were examined in 10 cats before and after two different weight-dropping spinal cord injuries. In six animals somatosensory evoked potentials (SEP) were also monitored. The recordings were done from epidural spinal cord electrodes. Before and after severe and light weight-dropping spinal cord injuries all 3 modalities were recorded at the same time intervals till the end of 4th hour postinjury. According to a scoring system, evoked potential changes below and above the level of injury were monitored, and compared with each other. This study showed that the different motor stimulation methods use different descending spinal tracts, and both can be useful as a monitoring tool. Both descending tracts carrying VsEP and MEP had similarly remarkable changes after severe spinal cord injury. These consisted of major deformation, development of an evoked injury potential and complete potential loss. During the 4 hour monitoring period, no case showed EP recovery in the severe injury group. Light spinal cord injury caused somewhat more deterioration in MEPs than VsEP. The higher numbers of severe potential alterations in the lightly injured animals suggest that MEP is a more sensitive method for spinal cord monitoring compared to VsEP and also to SEP. On the other hand, this sensitivity might be a disadvantage during intraoperative monitoring, if MEP alone were used.

Action Potentials↗
PubMed1998

Coronary artery surgery: the end of the beginning.

In each of the first three decades of myocardial revascularization, conventional treatment has been revised completely. This lecture comments on three areas of discovery that have shaped the evolution of myocardial revascularization: science, technology development, and revascularization. The discoveries in all three areas are inexorably interrelated. The single greatest lesson learned so far is that conduit performance carries more prognostic weight than any other factor. We have observed that vein graft atherosclerosis is predictable, and that the first-generation lipid lowering drugs have a favorable effect in patients who achieve marked LDL reduction. Biologically better revascularization begins with use of the internal thoracic artery for grafting to the anterior descending coronary artery. As the results of internal thoracic artery grafting are widely reported, arterial bypass revascularization has expanded, notably by radial and gastroepiploic arteries. The results of bilateral internal thoracic artery grafting are discussed, including large-scale registry results of internal thoracic artery usage in the United States. The internal thoracic artery is significantly underutilized. Diabetes affects both endoluminal and surgical revascularization. The new pharmacology in cardiology interventions shows promise in diminishing restenosis and thrombosis even in diabetic patients. Conversely, extended internal thoracic artery grafting may also benefit diabetic patients. Now we are entering a new age of minimally invasive coronary surgery. We have passed through the early stages of mini-thoracotomy, and we are moving on to access through 1-cm ports, intrathoracic cannulation, antegrade and retrograde myocardial protection, and computer guided three-dimensional vision and instrumentation. The potential for robotic control adds greater precision, ease of use, and safety. This new technology will be integrated with diagnostic information, intraoperative monitoring, anesthesia and perfusion data, cost accounting, and surgical note transcription. The operating room of the future will package intraoperative information and is adaptable to all surgical specialties. The future of coronary artery surgery will depend on minimally invasive techniques, all-arterial grafting, and selective lipid modification to reduce progressive atherosclerosis. The conclusion of this decade marks the end of the beginning. The new generation of cardiothoracic surgeons will share in an array of technology and research unmatched in previous decades.

Coronary Artery Disease↗
PubMed1999

Ventricular asystole during vagus nerve stimulation for epilepsy in humans.

Electrical stimulation of the vagus nerve, a recently available option for patients with refractory epilepsy, has demonstrated safety and efficacy. We report four patients with refractory epilepsy who experienced ventricular asystole intraoperatively during initial testing for implantation of the vagus nerve stimulator. Acute intraoperative vagus nerve stimulation may create ventricular asystole in humans. Extracorporeal cervical vagus nerve stimulation testing with continuous EKG monitoring intraoperatively before generator implantation is warranted.

Adult↗
PubMed1987

Improved preservation of facial nerve function with use of electrical monitoring during removal of acoustic neuromas.

Continuous spontaneous electromyographic activity and responses to electrical stimulation of the facial nerve in the surgical field were monitored in 48 patients undergoing primary removal of an acoustic neuroma. The operative and postoperative results in these patients were compared with the results in 48 patients who were matched for age and size of tumor and who underwent the same surgical procedure without intraoperative monitoring. Eighty-three percent of the patients had preoperative evidence of facial neuropathy, which was more severe with larger tumors. Postoperative facial nerve function was most accurately predicted on the basis of the extent of facial neuropathy on preoperative electrophysiologic testing. Anatomic preservation of the facial nerve in patients with large tumors was substantially improved in the monitored patients (67%) in comparison with those without monitoring (33%). No difference was noted in facial nerve function in the two groups of patients immediately postoperatively. By 3 months, the degree of improvement in the monitored group exceeded that in those who were not monitored, particularly in patients with medium-sized and large tumors.

Adult↗