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Harvey L Edmonds

Publications and source records attributed to Harvey L Edmonds.

12 recordsLinked to original sources
PubMed2006

Cerebral oximetry improves detection of sickle cell patients at risk for nocturnal cerebral hypoxia.

We previously used cerebral oximetry to identify low cerebral venous oxygen saturation in waking children with sickle cell disease (SCD). Because arterial oxyhemoglobin desaturation is common during sleep in SCD patients, this study compared both waking and sleeping systemic arterial and cerebral venous oxygenation dynamics in children with and without SCD. Seventeen African-American (AA) children with homozygous SCD [8 (4-15) years; 29% male; normal transcranial Doppler velocities] were compared with a control cohort (CON) comprised of six healthy AA children [9 (4-16) years, 33% male]. Standard all-night polysomnographic recordings were performed, including measurement of arterial oxygen saturation by pulse oximetry (SpO(2)). Regional cerebral oxygen saturation (rSO(2)) was measured non-invasively with cerebral oximetry. Intra-cohort comparisons examined the influence of sleep on SpO(2) and rSO(2) in the subjects. Inter-cohort comparisons of SpO(2), rSO(2,) and the rSO(2)/SpO(2) ratio assessed the impact of SCD on systemic and cerebral oxygenation during wakefulness and sleep. Cohort differences in SpO(2) were not statistically significant in either wakefulness or sleep. However, only in the SCD cohort was the magnitude of SpO(2) change statistically significant (P = 0.002). In contrast, both waking and sleep rSO(2) cohort median values did differ significantly [awake: CON 76 (67-86) vs. SCD 62 (58-71), P = 0.01; sleep: CON 65 (60-77) vs. SCD 55 (48-61), P = 0.01)]. The waking rSO(2)/SpO(2) ratio was also significantly lower in the SCD group [CON 0.78 (0.68-0.88) vs. SCD of 0.66 (0.61-0.72); P = 0.015]. During sleep, the ratio was also significantly lower in the SCD group [CON 0.71 (0.66-0.81) vs. SCD 0.59 (0.52-0.65); P = 0.011]. Our findings suggest that SCD patients may be at increased risk of cerebral hypoxia during both wakefulness and sleep.

Adolescent↗
PubMed2006

Alternative surgical strategy for the treatment of a mycotic aortic arch aneurysm.

We report the case of a 69-year-old man who presented with a symptomatic mycotic aneurysm of the aortic arch. Diagnosis was confirmed by positron emission tomography and by blood cultures positive for Salmonella species. A complete resection of the aortic arch process was performed via left thoracotomy using a cryopreserved aortic homograft and normothermic left heart bypass. The left-sided cerebral vessels were clamped, and adequacy of collateral left brain flow and oxygenation was confirmed by neurophysiologic monitoring. Using this less-invasive operative strategy, we avoided the risks inherent to deep hypothermic circulatory arrest and the use of prosthetic materials.

Aged↗
PubMed2005

A prospective analysis of intraoperative electromyographic monitoring of posterior cervical screw fixation.

OBJECTIVE: This is a prospective study of 26 patients undergoing posterior cervical spine instrumentation with lateral mass or pedicle screws to determine the correlation between intraoperative screw stimulation thresholds and the position of posterior cervical lateral mass and pedicle screws. METHODS: One hundred forty-seven posterior cervical screws (122 lateral mass screws and 25 C7 pedicle screws) in 26 patients were electrically stimulated intraoperatively and stimulation thresholds recorded. Computed tomography (CT) scans were taken postoperatively and were evaluated independently to assess screw position. Electromyographic (EMG) thresholds and CT data were compared to assess the accuracy of the EMG screw stimulation technique in detecting screw malposition. RESULTS: Intraoperative electrical stimulation was accurate in verifying screw position. A stimulation threshold of 15 mA provided a 99% positive predictive value (89% sensitivity, 87% specificity) that the screw was within the lateral mass or pedicle. Stimulation values of 10-15 mA provided a 13% predictive value (66% sensitivity, 90% specificity) that the screw was within the lateral mass or pedicle. A stimulation value of <10 mA provided a 100% predictive value that the screw was malpositioned (70% sensitivity, 100% specificity). CONCLUSIONS: Intraoperative evoked EMG monitoring is a valuable tool in posterior cervical instrumentation using lateral mass and pedicle screws. Stimulation thresholds in this study correlated with screw position. Stimulation values of >15 mA reliably predict acceptable screw position. Values between 10 and 15 mA are generally associated with acceptable screw position, although exploration is recommended. Values below 10 mA are associated with screw malposition and warrant exploration, repositioning, and possible removal.

Bone Screws↗
PubMed2005

Protective effect of neuromonitoring during cardiac surgery.

This study was a retrospective examination of the influence of multimodality neuromonitoring on the incidence of serious brain injury associated with a common type of adult cardiac surgery, coronary artery bypass grafting (CABG). Multichannel EEG, cerebral oximetry, and transcranial Doppler ultrasound were used to detect and correct imbalances in cerebral perfusion and oxygenation. Imbalances were detected in 59% of the cases and successfully corrected in all but 2%. In the absence of neuromonitoring, the expected incidence of serious brain injury is 6.1%. With neuromonitoring, the actual observed incidence was 3.0% (P = 0.03). The apparent improvement can be attributed primarily to a reduction in the number of nonembolic diffuse injuries.

Aged↗
PubMed2004

Assessment of cerebral tissue oxygenation in patients with sickle cell disease: effect of transfusion therapy.

This study used spatially resolved transcranial near-infrared spectroscopy (NIRS) to compare brain tissue oxygenation in sickle cell disease (SCD) patients with that of healthy children. In addition, NIRS was used to measure the dynamic response of cerebral oxygen balance to erythrocytapheresis. Transcranial NIRS measurements were obtained from 25 children with SCD who were not receiving transfusion or hydroxyurea therapy (NT-SCD). These patients were divided into two subgroups, those with mild (n = 10) or severe (n = 15) SCD symptoms. In addition, NIRS measurements were performed in 16 SCD patients with severe disease maintained on long-term erythrocytapheresis (T-SCD) and in 35 control children. The lowest mean brain tissue oxygen saturation occurred in the NT-SCD subgroup with severe symptoms (48 +/- 9%; P < 0.001 vs. control). NT-SCD patients with mild symptoms had higher saturation (62 +/- 8%; P < 0.001 vs. control), while the highest appeared in the control group (72 +/- 7%). In T-SCD patients, however, brain tissue oxygen saturations were higher than severely symptomatic NT-SCD children and similar to mildly symptomatic NT-SCD children (65 +/- 7%). Non-invasive measurements of brain tissue oxygenation with NIRS revealed that abnormal oxygen saturation levels in SCD patients correlated with the severity of their clinical manifestations. Additionally, cerebral oxygen balance seems to be favorably affected by erythro-cytapheresis.

Adolescent↗
PubMed2004

Cerebral oximetry for cardiac and vascular surgery.

The technology of transcranial near-infrared spectroscopy (NIRS) for the measurement of cerebral oxygen balance was introduced 25 years ago. Until very recently, there has been only occasional interest in its use during surgical monitoring. Now, however, substantial technologic advances and numerous clinical studies have, at least partly, succeeded in overcoming long-standing and widespread misunderstanding and skepticism regarding its value. Our goals are to clarify common misconceptions about near-infrared spectroscopy and acquaint the reader with the substantial literature that now supports cerebral oximetric monitoring in cardiac and major vascular surgery.

Brain↗
PubMed2003

New neurophysiology and central nervous system dysfunction.

PURPOSE OF REVIEW: The goal of this article is to summarize very recent technologic advances in neurophysiologic monitoring and to illustrate their potential benefit to critical care medicine. RECENT FINDINGS: Simplified, computer-processed electroencephalography devices now permit cost-effective, long-term critical care monitoring. They may be used alone to objectively assess sedation or coma level. In addition, these monitors serve as screening tools for more detailed electrophysiologic characterization of cortical dysfunction resulting from seizures, ischemia, or hypoxia. Somatosensory potentials broaden these capabilities to the entire neuraxis, whereas long-latency auditory evoked potentials facilitate measurement of changes in vigilance and cognition. Motor evoked potentials offer a sensitive and reliable method to determine the function of descending motor pathways in uncooperative or unresponsive patients. They may also yield a new measure of cortical excitability. New developments with transcranial Doppler ultrasonography promise noninvasive measures of cerebral perfusion pressure and particulate embolization. Near-infrared spectroscopy appears to enable noninvasive measurement of regional tissue oxygenation in both the brain and spinal cord. SUMMARY: When used together, these continuous measures of synaptic function, cerebral perfusion, and oxygenation give the clinician a vast amount of otherwise unobtainable information regarding the functional status of the central nervous system.

Central Nervous System Diseases↗
PubMed2002

Multi-modality neurophysiologic monitoring for cardiac surgery.

BACKGROUND: A high percentage of patients who undergo cardiac surgery experience persistent cognitive decline. The costs to insurers from brain injury associated with cardiac surgery is enormous. Furthermore, the same processes that injure the brain also appear to cause dysfunction of other vital organs. Therefore, there are great clinical and economic incentives to improve brain protection during cardiac surgery. This article discusses the methods of monitoring neurophysiologic function during heart surgery, including electroencephalography (EEG), near-infrared spectroscopy (NIRS), transcranial doppler (TCD) ultrasound, and cerebral oximetry, and analyzes the effectiveness of multi-modality neuromonitoring. METHODS: Neurophysiologic studies have implicated hypoperfusion and dysoxygenation as major causative factors for brain injury during cardiac surgery. Since these functional disturbances are often detectable and correctable, there is a new impetus to examine the role of neurophysiologic monitoring in brain protection. We have used a retrospective, single-surgeon case-control study to examine the influence on outcome following myocardial revascularization of multi-modality neuromonitoring, with modalities that include 4-channel EEG, bilateral cerebral oximetry, and single channel TCD. RESULTS: The majority of noteworthy functional disturbances detected by neuromonitoring can be corrected by simple adjustments in perfusion, oxygenation, or anesthetic administration. In more recalcitrant cases, pharmacological neuroprotection has proven effective. In addition to the substantial reductions in length of hospital stay, costs, and neurologic complications, the results of neuromonitoring suggest a possible benefit to other vital organ systems. Future studies of neuromonitoring efficacy should not overlook these important accessory benefits. CONCLUSION: This study provides the clearest evidence to date that multi-modality neuromonitoring for cardiac surgery is safe, clinically beneficial, and cost-effective. Although neuromonitoring involves negligible risk and modest costs, it's benefits for patient outcome and cost control are substantial.

Brain Diseases↗