C. Thomas Wass

Temperature Changes of greater or equal to 1 degree Celsius Alter Functional Neurologic Outcome and Histopathology in a Canine Model of Complete Cerebral Ischemia

Background Changes in basal temperature of greater or equal to 1 degree Celsius (e.g., fever-induced hyperthermia or anesthesia-related hypothermia) are a common occurrence in neurologically impaired patients. The current study tested the hypothesis that temperature changes as small as 1 degree Celsius or 2 degrees Celsius would significantly alter post-ischemic functional neurologic outcome and cerebral histopathology. The hypothesis was tested in a canine model of transient, complete cerebral ischemia.

Glucose Modulation of Ischemic Brain Injury: Review and Clinical Recommendations

Ischemic brain injury is the third-leading cause of death among Americans and the leading cause of serious disability. Based on studies of animal models, a substantial amount of experimental evidence shows that hyperglycemia at the onset of brain ischemia worsens postischemic neurologic outcome. Consistent with these observations, hyperglycemia also is associated with a worsening of postischemic brain injury in humans. In humans, however, data are often difficult to interpret because of problems in determining the timing of hyperglycemia relative to a critical ischemic event and in elucidating the effect of coexisting pathophysiologic processes (for example, a stress response) on outcome. Glucose modulation of neurologic injury is observed when ischemia is either global (for example, that accompanying cardiac arrest or severe systemic hypotension) or focal (for example, that accompanying thrombotic or embolic stroke). Toxicity is probably the result of an intracellular lactic acidosis. Specifically, the associated hydrogen ions are injurious to neurons and glia. On the basis of these factors, we recommend diligent monitoring of blood glucose concentrations in patients who are at increased risk for new-onset, ongoing, or recurring cerebral ischemia. In such patients, the use of fluid infusions, corticosteroid drugs, and insulin, as well as stress management, should be tailored to treat preexisting hyperglycemia and prevent new-onset hyperglycemia. Maintenance of normoglycemia is recommended. When one attempts to treat preexisting hyperglycemia, care should be taken to avoid rapid fluid shifts, electrolyte abnormalities, and hypoglycemia, all of which can be detrimental to the brain.

Occurrence of Potentially Detrimental Temperature Alterations in Hospitalized Patients at Risk for Brain Injury

OBJECTIVE To ascertain the incidence and timing of fever in patients at risk for temperature modulation of brain injury resulting from ischemia or trauma. DESIGN We retrospectively reviewed the medical records of patients admitted between January 1991 and December 1994. MATERIAL AND METHODS We investigated three groups of hospitalized patients considered at risk for ongoing brain injury resulting from a prior cerebral insult: successful resuscitation from out-of-hospital cardiac arrest (CA), subarachnoid hemorrhage (SAH), or traumatic closed-head injury (CHI). Forty patients per condition were randomly selected from those who survived for more than 24 hours after hospital admission. RESULTS During the initial 72 hours of hospitalization, temperature increases to 38 degrees C or more (that is, temperatures previously reported to worsen neurologic outcome after brain injury) were noted in 83% of patients with CA, 70% of those with SAH, and 68% of those with CHI. Within the cohort of febrile patients, 18 to 44% of all temperature measurements were 38 degrees C or higher, and the febrile episodes occurred randomly throughout the study interval. Fewer than one-eighth of the febrile patients received drugs possessing antipyretic properties (such as aspirin or acetaminophen) in a dose appropriate to treat fever. No other method of temperature control (for example, physical means) was used in any patient. The fractions of patients who were dismissed from the hospital with permanent neurologic injury were as follows: CA, 20%; SAH, 45%; and CHI, 43%. CONCLUSION In these hospitalized patients at risk for ongoing brain injury, the incidence of temperature increases within the range reported to worsen neurologic outcome (elevations of 1.0 degree C or more) was very high. The characterization of these potentially injurious, randomly occurring, and traditionally undertreated temperature increases may have implications for the design of future protocols aimed at providing cerebral protection.

Preoperative Gabapentin for Acute Post-thoracotomy Analgesia: A Randomized, Double-Blinded, Active Placebo-Controlled Study

Background:  The role of preoperative gabapentin in postoperative pain management is not clear, particularly in patients receiving regional blockade. Patients undergoing thoracotomy benefit from epidural analgesia but still may experience significant postoperative pain. We examined the effect of preoperative gabapentin in thoracotomy patients.

The Effects of Remifentanil on Epileptiform Discharges during Intraoperative Electrocorticography in Patients Undergoing Epilepsy Surgery

Summary:  Purpose: High‐dose i.v. opioids (e.g., alfentanil, 50 μg/kg bolus) are known to increase the intraoperative reading of epileptiform activity during epilepsy surgery (ES), thereby facilitating localization of the epileptogenic zone (i.e., the site of ictal onset and initial seizure propagation). However, this phenomenon has not been studied with remifentanil (i.e., a novel ultra‐short acting opioid). The purpose of the present study was to evaluate the effect of remifentanil on electrocorticography (ECoG) during ES.

Risk for perioperative myocardial infarction and mortality in patients undergoing hip or knee arthroplasty: the role of anemia

BACKGROUND: Anemia is common in patients undergoing surgery. This study was designed to determine whether preoperative anemia represents an independent risk factor for 30‐day mortality and nonfatal myocardial infarction (death/MI) in patients undergoing major orthopedic arthroplasty surgery.

Motor Evoked Potential Monitoring during Cryoablation of Musculoskeletal Tumors

PURPOSE To describe the use of intraprocedural motor evoked potential (MEP) monitoring to minimize risk of neural injury during percutaneous cryoablation of perineural musculoskeletal tumors. MATERIALS AND METHODS A single-institution retrospective review of cryoablation procedures performed to treat perineural musculoskeletal tumors with the use of MEP monitoring between May 2011 and March 2013 yielded 59 procedures to treat 64 tumors in 52 patients (26 male). Median age was 61 years (range, 4-82 y). Tumors were located in the spine (n = 27), sacrum (n = 3), retroperitoneum (n = 4), pelvis (n = 22), and extremities (n = 8), and 21 different tumor histologies were represented. Median tumor size was 4.0 cm (range, 0.8-15.0 cm). Total intravenous general anesthesia, computed tomographic guidance, and transcranial MEP monitoring were employed. Patient demographics, tumor characteristics, MEP findings, and clinical outcomes were assessed. RESULTS Nineteen of 59 procedures (32%) resulted in decreases in intraprocedural MEPs, including 15 (25%) with transient decreases and four (7%) with persistent decreases. Two of the four patients with persistent MEP decreases (50%) had motor deficits following ablation. No functional motor deficit developed in a patient with transient MEP decreases or no MEP change. The risk of major motor injury with persistent MEP changes was significantly increased versus transient or no MEP change (P = .0045; relative risk, 69.8; 95% confidence interval, 5.9 to > 100). MEP decreases were 100% sensitive and 70% specific for the detection of motor deficits. CONCLUSIONS Persistent MEP decreases correlate with postprocedural sustained motor deficits. Intraprocedural MEP monitoring helps predict neural injury and may improve patient safety during cryoablation of perineural musculoskeletal tumors.

Perioperative interscalene blockade: an overview of its history and current clinical use

Use of single-dose and continuous interscalene brachial plexus block (ISB) are gaining widespread popularity. When compared with general anesthesia, ISB has been reported to provide superior postoperative analgesia with fewer side effects, and it is associated with greater patient satisfaction. Anatomical landmarks are readily identifiable, which contributes to the ease of performing this block. In the future, we anticipate increased use of continuous interscalene catheters or injection of biodegradable local anesthetic impregnated microspheres to provide prolonged perioperative outpatient analgesia.

Changes in red blood cell transfusion practice during the past two decades: a retrospective analysis, with the Mayo database, of adult patients undergoing major spine surgery

BACKGROUND: Others have reported significant changes in red blood cell (RBC) transfusion practice during the past two decades during knee, hip, prostate, and carotid surgery. Similar data for patients undergoing major spine surgery, however, are not available.

Risk for perioperative myocardial infarction and mortality in patients undergoing hip or knee arthroplasty

BACKGROUND: Anemia is common in patients undergoing surgery. This study was designed to determine whether preoperative anemia represents an independent risk factor for 30‐day mortality and nonfatal myocardial infarction (death/MI) in patients undergoing major orthopedic arthroplasty surgery.