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Eric J Heyer

Publications and source records attributed to Eric J Heyer.

14 recordsLinked to original sources
PubMed2006

High dose magnesium infusions are not associated with increased pressor requirements after carotid endarterectomy.

INTRODUCTION: Although magnesium provides cerebral protection in animal stroke models, magnesium therapy has significant side effects in humans. Therefore, we sought to examine the incidence of alpha-agonist treated hypotension in our ongoing, prospective, randomized, double-blind, placebo-controlled Phase I/IIa dose escalation study of magnesium therapy in patients undergoing carotid endarterectomy. METHODS: Eighty patients undergoing elective carotid endarterectomy were randomly assigned to a placebo control group (n = 38) or to one of the three intravenous magnesium groups. Magnesium levels were obtained before induction, and then 15 minutes, 1 hour, 2 hours, 6 hours, 12 hours, and 24 hours after a loading dose and infusion. After surgery, a target systolic blood pressure range was chosen, and the amount and duration of phenylephrine needed to maintain that pressure was compared across treatment groups. RESULTS: All treatment groups achieved levels significantly different from baseline at 12 and 24 hours (P < 0.01). Magnesium treatment did not significantly increase the proportion of patients requiring pressure support. For those requiring pressure support, the amount and average duration of phenylephrine required was not different between control patients and those receiving magnesium, even when the individual minimum systolic blood pressures required were subdivided on the basis of dose of magnesium administered. CONCLUSION: There were no significant differences detected in the 1) percentage of patients requiring pressor support, 2) the duration of postoperative pressor support, or 3) the amount of phenylephrine support needed between controls and magnesium treated patients. The percentage of patients requiring pressure support depended on the minimum systolic blood pressure ordered after surgery.

Adrenergic alpha-Agonists↗
PubMed2006

Neuropsychological dysfunction in the absence of structural evidence for cerebral ischemia after uncomplicated carotid endarterectomy.

OBJECTIVE: Neurocognitive dysfunction has been shown to occur in roughly 25% of patients undergoing carotid endarterectomy (CEA). Despite this, little is known about the mechanism of this injury. Recently, several groups have shown that new diffusion weighted imaging (DWI)-positive lesions are seen in 20% of patients undergoing CEA. We investigated to what degree neurocognitive dysfunction was associated with new DWI lesions. METHODS: Thirty-four consecutive patients undergoing CEA were subjected to pre- and postoperative cognitive evaluation with a battery of neuropsychological tests. Postoperative magnetic resonance imaging was performed in all patients within 24 hours of surgery. Lesions that showed high signal on DWI and restricted diffusion on apparent diffusion coefficient maps but no abnormal high signal on the fluid-attenuated inversion recovery images were considered hyperacute. RESULTS: Cognitive dysfunction was seen in eight (24%) patients. New hyperacute DWI lesions were seen in three (9%). Only one (13%) of the patients with cognitive dysfunction had a new DWI lesion. Two thirds of the new DWI lesions occurred in the absence of cognitive deterioration. Patients with cognitive dysfunction had significantly longer carotid cross-clamp times. CONCLUSION: Neurocognitive dysfunction after CEA does not seem to be associated with new DWI positive lesions.

Aged↗
PubMed2006

Predictors of neurocognitive decline after carotid endarterectomy.

OBJECTIVE: Although the incidence of stroke after carotid endarterectomy (CEA) is low (1-3%), approximately 25% of patients experience subtle declines in postoperative neuropsychometric function. No studies have investigated the risk factors for this neurocognitive change. We sought to identify predictors of postoperative neurocognitive dysfunction. METHODS: We enrolled 186 CEA patients, with both symptomatic and asymptomatic stenosis, to undergo a battery of neuropsychometric tests preoperatively and on postoperative Days 1 and 30. Neurocognitive dysfunction was defined as a two standard deviation decline in performance compared with a similarly aged control group of lumbar laminectomy patients. Univariate logistic regression was performed for age, sex, obesity, smoking, symptomatology, diabetes mellitus, hypertension, hypercholesterolemia, use of statin medication, previous myocardial infarction, previous CEA, operative side, duration of surgery, duration of carotid cross-clamp, and weight-adjusted doses of midazolam and fentanyl. Variables achieving univariate P < 0.10 were included in a multivariate analysis. Data is presented as (odds ratio, 95% confidence interval, P-value). RESULTS: Eighteen and 9% of CEA patients were injured on postoperative Days 1 and 30, respectively. Advanced age predicted neurocognitive dysfunction on Days 1 and 30 (1.93 per decade, 1.15-3.25, 0.01; and 2.57 per decade, 1.01-6.51, 0.049, respectively). Additionally, diabetes independently predicted injury on Day 30 (4.26, 1.15-15.79, 0.03). CONCLUSIONS: Advanced age and diabetes predispose to neurocognitive dysfunction after CEA. These results are consistent with risk factors for neurocognitive dysfunction after coronary bypass and major stroke after CEA, supporting an underlying ischemic pathophysiology. Further work is necessary to determine the role these neurocognitive deficits may play in appropriately selecting patients for CEA.

Age Factors↗
PubMed2006

Comparison of electrophysiologic monitors with clinical assessment of level of sedation.

OBJECTIVE: To assess the correlation between 2 clinical sedation scales and 2 electroencephalographic (EEG)-based monitors used during surgical procedures that required mild to moderate sedation. PATIENTS AND METHODS: Patients scheduled for elective surgery participated in this Institutional review board-approved study from March 2003 to February 2004. Level of sedation was determined both clinically using the Ramsay and the Observer's Assessment of Alertness/Sedation scales and with 2 EEG measures (the Bispectral Index version XP [BIS XP] or the Patient State Analyzer [PSA 4000]). Correlation between these 2 measures of sedation were tested using nonparametric statistical tests. RESULTS: The BIS XP monitor was used in 26 patients, and the PSA 4000 monitor was used in 24 patients. The Ramsay and Observer's Assessment of Alertness/Sedation scores correlated with each other (r = -0.96; P < .001) and with both the BIS XP (r = -0.89 and r = 0.91, respectively; P < .001) and the PSA 4000 (r = -0.80 and r = 0.80, respectively; P < .001) values. However, this correlation was strongest only at the extremes. Between the BIS XP and PSA 4000 values of 61 and 80, the clinical sedation scores varied greatly. CONCLUSION: On the basis of our results, these EEG-based monitors cannot reliably distinguish between light and deep sedation.

Computer Terminals↗
PubMed2005

Elevations in preoperative monocyte count predispose to acute neurocognitive decline after carotid endarterectomy for asymptomatic carotid artery stenosis.

BACKGROUND AND PURPOSE: Although the incidence of major stroke attributable to carotid endarterectomy (CEA) is low (1% to 2%), approximately 25% of patients experience subtle postoperative neurocognitive dysfunction. This study examines whether preoperative leukocyte profiles predict cognitive outcome in asymptomatic CEA patients. METHODS: Sixty-nine asymptomatic CEA patients underwent neuropsychometric testing preoperatively and on postoperative day 1 (POD1). Preoperative white blood cell counts and differentials were obtained. Logistic regression was performed for risk factors for neurocognitive decline. Variables achieving univariate P<0.10 were included in multivariate analysis. RESULTS: Eighteen (26%) patients experienced neurocognitive decline on POD1; multivariate analysis demonstrated that preoperative monocyte count (P=0.011) and age (P=0.02) independently predicted outcome. CONCLUSIONS: Preoperative monocyte count and age are independently associated with acute neurocognitive decline after CEA for asymptomatic stenosis.

Age Factors↗
PubMed2005

Bilateral bispectral index monitoring during suppression of unilateral hemispheric function.

Bispectral Index (BIS) has been used to monitor level of "sedation" based on the electroencephalogram (EEG). Patients evaluated for surgery to control a seizure disorder undergo Wada testing, during which one hemisphere is rendered functionally inactive after injecting a short-acting barbiturate. We surmised that the BIS values would reflect these functional changes. Eight epileptic patients were enrolled. A full array of 21 EEG electrodes and 2 BIS XP (Quatro) strips over each frontal region of the scalp were applied. The EEG was continuously recorded. BIS values from each hemisphere were recorded every minute. Angiography was performed by advancing a catheter into each internal carotid artery. Amobarbital or methohexital was injected until the patient developed a hemiparesis. The EEG confirmed a significant lateralized cortical effect of the barbiturate. Repeated measures analysis of variance was used to analyze the differences between the BIS values from monitor electrode strips placed on the left (left BIS) and the right (right BIS) sides of the head as well as the differences in the left and right BIS values before and after each injection of the barbiturate. Injection of barbiturate into either the left or right internal carotid artery produced a significant change on the 21-electrode EEG. However, there was no difference between left BIS to right BIS values (P = 0.84). With repeated injections of barbiturates, some patients became sedated. At these times, both left BIS and right BIS values decreased together before and after injection of barbiturate. The BIS monitor was unable to distinguish significant hemispheric EEG and clinical functional changes except when the patient became sedated.

Adult↗
PubMed2004

The effects of propofol, small-dose isoflurane, and nitrous oxide on cortical somatosensory evoked potential and bispectral index monitoring in adolescents undergoing spinal fusion.

In this study we compared the effects of propofol, small-dose isoflurane, and nitrous oxide (N(2)O) on cortical somatosensory evoked potentials (SSEP) and bispectral index (BIS) monitoring in adolescents undergoing spinal fusion. Twelve patients received the following anesthetic maintenance combinations in a randomly determined order: treatment #1: isoflurane 0.4% + N(2)O 70% + O(2) 30%; treatment #2: isoflurane 0.6% + N(2)O 70% + O(2) 30%; treatment #3: isoflurane 0.6% + air + O(2) 30%; treatment #4: propofol 120 microg . kg(-1) . min(-1) + air + O(2) 30%. Cortical SSEP amplitudes measured during anesthesia maintenance with treatment #3 (isoflurane 0.6%/air) were more than those measured during maintenance with treatment #1 (isoflurane 0.4%/N(2)O 70%) (P < 0.0001) and treatment #2 (isoflurane 0.6%/N(2)O 70%) (P < 0.0052). Cortical SSEP amplitudes measured during treatment #4 (propofol 120 microg . kg(-1) . min(-1)/air) were more than treatment #1 (isoflurane 0.4%/N(2)O 70%) (P < 0.0001), treatment #2 (Iso 0.6%/N(2)O 70%) (P < 0.0007), and treatment #3 (isoflurane 0.6%/air) (P < 0.0191). In addition, average BIS values measured during treatments 1, 2, 3 and 4 were 62, 62, 61, and 44 respectively. Only treatment #4 (propofol 120 microg . kg(-1) . min(-1)/air) uniformly maintained BIS values less than 60. Our study demonstrates that propofol better preserves cortical SSEP amplitude measurement and provides a deeper level of hypnosis as measured by BIS values than combinations of small-dose isoflurane/N(2)O or small-dose isoflurane alone.

Adolescent↗
PubMed2003

Failure of intraoperative jugular bulb S-100B and neuron-specific enolase sampling to predict cognitive injury after carotid endarterectomy.

OBJECTIVE: Cognitive decline occurs in 25% of patients after carotid endarterectomy (CEA). Elevated serum concentrations of S-100B and neuron-specific enolase (NSE) occur after stroke, and serum S-100B levels at 24 hours are associated with clinical outcome after both stroke and CEA. We hypothesized that we could detect acute elevations in serum levels of these markers obtained intraoperatively from the jugular bulb (JB) and that these elevations would predict cognitive dysfunction postoperatively as measured by neuropsychometric test performance. METHODS: Forty-three patients scheduled for elective CEA were assessed with a battery of neuropsychometric tests before and 1 day after surgery. Before the carotid artery was clamped, a 6-French Fogarty catheter was inserted into the facial vein and threaded 6 cm rostrally into the JB. Serum samples were withdrawn from this catheter and simultaneously from a radial arterial catheter (A-line) at three time points: before clamping, 15 minutes into clamping, and after unclamping the carotid artery. Concentrations between groups were compared by analysis of variance and paired t tests. RESULTS: Total deficit scores were significantly worse in 13 (30%) of the 43 patients 1 day after surgery. There was a trend toward elevations in JB concentrations of S-100B relative to A-line levels 15 minutes after cross-clamping (11% elevation, P = 0.079, paired t test). In addition, 15 minutes after clamping of the carotid artery, levels of S-100B from the JB were significantly elevated compared with levels at baseline (P = 0.040, one-way analysis of variance). No significant changes were found between any time point in levels of S-100B from the A-line blood or of NSE from either the JB or the A-line. Subtle cognitive decline after CEA was not correlated with intraoperative levels of S-100B or NSE, but there was a weak, statistically nonsignificant, association between a rise in 15-minute S-100B levels and cognitive injury that was not seen with JB samples. CONCLUSION: Although intraoperative levels of S-100B and NSE from the JB failed to predict cognitive injury, carotid cross-clamping, independent of injury, seems to be associated with early elevations in S-100B.

Aged↗
PubMed2002

A controlled prospective study of neuropsychological dysfunction following carotid endarterectomy.

BACKGROUND: Although subtle cognitive injury as revealed by neuropsychological testing occurs in a substantial number of patients following carotid endarterectomy (CEA), there is controversy about whether this finding is a result of the surgery or the anesthesia. OBJECTIVES: To examine the changes in neuropsychological test performance in patients following CEA vs a control group of patients older than 60 years following spine surgery, so as to determine whether neuropsychological dysfunction after CEA is a result of surgery or anesthesia. METHODS: Patients undergoing CEA (n = 80) and lumbar spine surgery (n = 25) were assessed with a battery of neuropsychological tests preoperatively and on postoperative days 1 and 30. The neuropsychological performance of patients in the control group was used to normalize performance for patients in the CEA group, by calculating z scores using the mean and SD of the change scores in the control group. Significant cognitive dysfunction was defined as performance that exceeded 2 SDs above the mean performance of patients in the control group. RESULTS: Postoperative days 1 and 30 total deficit scores were significantly worse in the CEA group compared with the controls. When individual test results were examined, the CEA group performed significantly worse than the controls on the Rey Complex Figure test and Halstead-Reitan Trails B on day 1, and on the Rey Complex Figure on day 30. Overall, cognitive dysfunction was seen in 22 patients (28%) in the CEA group on day 1 and in 11 (23%) of 48 patients on day 30. CONCLUSIONS: Subtle cognitive decline following CEA occurs and persists for at least several weeks after surgery. This decline was absent in a control group.

Aged↗
PubMed2002

Heparin-bonded cardiopulmonary bypass circuits reduce cognitive dysfunction.

OBJECTIVE: To determine the incidence of cerebral dysfunction in cardiac surgical patients exposed to heparin-bonded cardiopulmonary bypass (HB-CPB) versus nonheparin-bonded cardiopulmonary bypass (NH-CPB) circuits through neuropsychometric testing and to correlate these findings with markers of the systemic inflammatory response to CPB. DESIGN: Prospective, randomized, blinded clinical trial. SETTING: University hospital. PARTICIPANTS: Sixty-one patients undergoing elective cardiac surgery. INTERVENTIONS: A cohort of 61 patients scheduled for elective coronary artery bypass graft surgery were prospectively randomized to receive either HB-CPB or NH-CPB circuits during surgery. Patients were evaluated for cerebral injury using a battery of neuropsychometric tests at the following 3 time points: (1) before surgery as a baseline examination, (2) postoperative day 5, and (3) postoperative week 6. Blood samples were drawn to measure inflammatory markers at the following time points: (1) preincision, after induction of anesthesia, (2) 15 minutes after onset of CPB, (3) 30 minutes after CPB, (4) 6 hours postoperatively, and (5) 24 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Neuropsychometric performance was evaluated by group-rate and event-rate analyses. By group-rate analysis, patients undergoing surgery with HB-CPB performed significantly better at 5 days after surgery on 2 neuropsychometric tests (trails A [p < 0.01] and finger tapping with the dominant hand [p < 0.01]) and at 6 weeks after surgery on one neuropsychometric test (trails A [p < 0.01]). By event-rate analysis, at 5 days, patients undergoing surgery with HB-CPB circuits had less cognitive dysfunction (p < 0.05) compared with patients undergoing surgery with NH-CPB circuits. Serum samples were analyzed to evaluate markers of complement activation (C3a), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6), and coagulation (thrombin-antithrombin complex [TAT]) using the quantitative sandwich enzyme immunoassay technique. Although there were no significant differences in cytokine activation in either group, C3a was significantly higher in the NH-CPB group intraoperatively at 1 hour after CPB (p < 0.05), and TAT was higher in the HB-CPB group at 24 hours after surgery (p < 0.05). CONCLUSIONS: Patients undergoing cardiac surgery with CPB have less postoperative cognitive dysfunction during CPB when HB-CPB circuits are employed. Although there was a relationship, this finding did not correlate with decreased complement activation intraoperatively and activation of coagulation postoperatively.

Antithrombin III↗
PubMed2002

Anesthesia for intraoperative neurophysiologic monitoring of the spinal cord.

Intraoperative neurophysiologic monitoring (INM) using somatosensory and motor evoked potentials (MEPs) has become popular to reduce neural risk and to improve intraoperative surgical decision making. Intraoperative neurophysiologic monitoring is affected by the choice and management of the anesthetic agents chosen. Because inhalational and intravenous anesthetic agents have effects on neural synaptic and axonal functional activities, the anesthetic effect on any given response will depend on the pathway affected and the mechanism of action of the anesthetic agent (i.e., direct inhibition or indirect effects based on changes in the balance of inhibitory or excitatory inputs). In general, responses that are more highly dependent on synaptic function will have more marked reductions in amplitude and increases in latency as a result of the synaptic effects of inhalational anesthetic agents and similar effects at higher doses of intravenous agents. Hence, recording cortical somatosensory evoked potentials and myogenic MEPs requires critical anesthetic choices for INM. The management of the physiologic milieu is also important as central nervous system blood flow, intracranial pressure, blood rheology, temperature, and arterial carbon dioxide partial pressure produce alterations in the responses consistent with the support of neural functioning. Finally, the management of pharmacologic neuromuscular blockade is critical to myogenic MEP recording in which some blockade may be desirable for surgery but excessive blockade may eliminate responses. A close working relationship of the monitoring team, the anesthesiologist, and the surgeon is key to the successful conduct and interpretation of INM.

Anesthesia↗
PubMed2002

Cerebral injury predicted by transcranial Doppler ultrasonography but not electroencephalography during carotid endarterectomy.

When shunts are selectively used during carotid endarterectomy, the adequacy of collateral cerebral blood flow (CBF) after the carotid artery is clamped is determined by monitors based on different physiologic measurements. In this series of three patients, we used electroencephalography (EEG) to measure neuronal electrical activity and transcranial Doppler ultrasonography (TCD) to measure CBF velocity. In each of our cases, the EEG was unchanged from preclamp values, while TCD CBF velocity was dramatically reduced. All three patients had transient neuropsychometric or neurologic changes after surgery, which resolved.

Aged↗
PubMed2002

Dexmedetomidine may impair cognitive testing during endovascular embolization of cerebral arteriovenous malformations: a retrospective case report series.

After the reported successful use of dexmedetomidine to sedate patients in the intensive care unit without respiratory depression, we began to use dexmedetomidine for interventional neuroradiologic procedures. We report on five patients who had dexmedetomidine administered for sedation during embolization of cerebral arteriovenous malformations. All patients were comfortably sedated and breathing spontaneously. However, although patients were awake and following simple commands 10 minutes after the discontinuation of the infusion of dexmedetomidine, they were nevertheless unable to undergo cognitive testing. They were still unable to undergo cognitive testing 45 minutes after the infusion was stopped. In contrast, 10 minutes after the discontinuation of the infusion of propofol, all patients were awake, alert, cooperative, and able to undergo cognitive testing without difficulty. In conclusion, on examination of five non-randomly selected case records, we found that dexmedetomidine significantly prevented neurologic and cognitive testing.

Adjuvants, Anesthesia↗