Brain Energy Metabolism and Hyperglycemia in Traumatic Brain Injury, Assignments of Neuroscience

Download Brain Energy Metabolism and Hyperglycemia in Traumatic Brain Injury and more Assignments Neuroscience in PDF only on Docsity! QUIZ #30 Quiz 30, Glucose and the Brain M. Angele Theard, MD, Legacy Emanuel Medical Center, Portland, OR Quiz team: Shobana Rajan, MD; Suneeta Gollapudy, MD, Verghese Cherian, MD This Quiz is published on behalf of the education committee of SNACC M. Angele Theard, MD Anesthesiologist, Legacy Emanuel Medical Center, Portland, Oregon Quiz team: Shobana Rajan, MD; Suneeta Gollapudy, MD, Verghese Cherian,MD This Quiz is published on behalf of the education committee of SNACC To Q 1 ZINC Atomic #30 Density: 7.134gm/cm3 1. ALL ARE TRUE REGARDING BRAIN METABOLISM EXCEPT a. Energy formation for the brain is derived from a catabolic process which leads to the formation of ATP b. Most of the Transport of glucose into the brain requires energy c. Ionic homeostasis in the brain required for cellular function requires energy d. In the absence of oxygen, anaerobic glycolysis produces 2 molecules of ATP per glucose which is inadequate to meet the brain’s energy needs To Q2 C. IONIC HOMEOSTASIS IN THE BRAIN REQUIRED FOR CELLULAR FUNCTION REQUIRES ENERGY This is a true statement. Ionic homeostasis which requires energy in the from of ATP is mandatory for excitatory synaptic transmission in the brain. Mitochondrial derived Na/K ATPase is necessary to pump K+ ions inside the cells and Na out of cells, thereby preserving the ionic gradient across cells. Changes from the resting membrane potential achieved in large part by Potassium’s movement along it’s concentration gradient (negative resting membrane potential of about 90mV) is necessary for generation of action potentials necessary for normal nerve cell function. Kass, Cotrell Brain metabolism, the pathophysiology of brain injury, and potential beneficial agents and techniques in Cotrell and Young’s Neuroanesthesia, 5th ed. 2010;Mosby Elsevier, PA Incorrect Answer Try Again D. IN THE ABSENCE OF OXYGEN, ANAEROBIC GLYCOLYSIS PRODUCES 2 MOLECULES OF ATP PER GLUCOSE WHICH IS INADEQUATE TO MEET THE BRAIN’S ENERGY NEEDS This statement is true. Under normal aerobic conditions, glycolysis, the citric acid cycle and finally oxidative phosphorylation will produce 38 ATP per glucose molecule. In the absence of oxygen, anaerobic glycolysis converts pyruvate to lactate regenerating NAD producing only two ATP molecules . ATP is necessary to pump K+ ions inside the cells and Na out of cells, thereby preserving the ionic gradient across cells. Without these energy dependent pumps, ions would continue to leak down their electrochemical gradients reducing the membrane potential to 0, causing cells to depolarize and die. Kass, Cotrell Brain metabolism, the pathophysiology of brain injury, and potential beneficial agents and techniques in Cotrell and Young’s Neuroanesthesia, 5th ed. 2010;Mosby Elsevier, PA Incorrect Answer Try Again 2. HYPERGLYCEMIA IN TRAUMATIC BRAIN INJURED (TBI) PATIENTS IS DUE TO ALL OF THE FOLLOWING EXCEPT a. Cortisol b. Gluconeogenesis c. Opioids d. Corticotrophin To Q3 C. OPIOIDS Opioids are commonly used in anesthesia in part to suppress hypothalamic and pituitary hormone secretion. Morphine suppresses the release of corticotrophin from the hypothalamus and has also been found to inhibit cortisol release. In cardiac surgery Fentanyl, Sufentanil, and Alfentanil suppress pituitary hormone secretion ultimately limiting glucose production. Desborough JP, The Stress response to trauma and surgery, Br J A, 2000;85(1):109-17 Correct! To Q3 Back to Q2 D. CORTICOTROPHIN In response to trauma/surgical stress, the hypothalamus releases corticotrophin releasing hormone which stimulates the anterior pituitary to release corticotrophin (ACTH) which stimulates the adrenal cortex to release cortisol stimulating gluconeogenesis. Desborough JP, The Stress response to trauma and surgery, Br J A 2000;85(1):109-17 Incorrect Answer Try Again 3. WHICH OF THE FOLLOWING IS TRUE REGARDING SERUM GLUCOSE IN PATIENTS WITH INJURED BRAIN a. Hypoglycemia has little impact on injured brain b. Hyperglycemia is not a problem in patients with cerebral ischemia. c. Perioperative hyperglycemia is common in adults but not children undergoing craniotomy for traumatic brain injury. d. Patients with intraoperative hyperglycemia during neurosurgical procedures are more likely to develop postoperative neurologic dysfunction. To Q 4 C. PERIOPERATIVE HYPERGLYCEMIA IS COMMON IN ADULTS BUT NOT IN CHILDREN UNDERGOING CRANIOTOMY FOR TRAUMATIC BRAIN INJURY. Intraoperative hyperglycemia is common in adults undergoing urgent/emergent craniotomy for TBI, with up to 15% of patients experiencing new onset hyperglycemia. Similarly, in a retrospective cohort study evaluating 105 children ≤13 years for emergency craniotomy for TBI, 17% had persistent hyperglycemia. Sharma D, Perioperative management of adult traumatic brain injury, Anesthesiology clinics, 2012;30:333-346 Sharma D, et al, Incidence and risk factors for perioperative hyperglycemia in children with traumatic brain injury, Anesth Analg. 2009;108:81-9 Incorrect Answer Try Again D. PATIENTS WITH INTRAOPERATIVE HYPERGLYCEMIA DURING NEUROSURGICAL PROCEDURES ARE MORE LIKELY TO DEVELOP POSTOPERATIVE NEUROLOGIC DYSFUNCTION. In a retrospective examination of 1000 patients from the Intraoperative Hypothermia for Aneurysm Surgery trial database (IHAST) who underwent aneurysm clipping within 14 days of subarachnoid hemorrhage (SAH), Pasternak et al noted that at 3 months after surgery, those with glucose >129mg/dL were more likely to have impaired cognition and those with glucose > 152 mg/dL were more likely to experience gross neurologic dysfunction as assessed by the national institute of health stroke scale. Pasternak J, Hyperglycemia in patients undergoing cerebral aneurysm surgery: its association with long–term gross neurologic and neuropsychological function. Mayo Clin Proc. 2008;83(4):406-17 To Q4 Back to Q3 4. GLUCOSE CONTROL IS IMPORTANT IN ORDER TO LIMIT SECONDARY BRAIN INJURY. ALL OF THE FOLLOWING ARE TRUE REGARDING THE MANAGEMENT OF GLUCOSE LEVELS EXCEPT. a. Maintaining serum glucose ≤180 mg/dl (≤10mmol/L) is reasonable in order to avoid extremes of glucose in TBI patients. b. Intensive insulin therapy carries an increased risk of death c. Intensive insulin therapy carries an increased risk of hypoglycemia d. Tight glucose control between 80 and 110mg/dl is recommended in critically ill patients To Q5 C. INTENSIVE INSULIN THERAPY CARRIES AN INCREASED RISK OF HYPOGLYCEMIA This statement is true. In a prospective study of 97 patients with severe traumatic brain injury randomized to traditional insulin therapy for glucose levels >220 md/dl or more intensive therapy with glucose goals of between 80 and 120 md/dl, Bilotta et al noted that the intensive insulin therapy group had significantly more hypoglycemic episodes. A benefit of intensive insulin therapy included a shorter ICU stay, however both groups had similar mortality and neurologic outcome. Bilotta et al, Intensive insulin therapy after severe traumatic brain injury: a randomized clinical trial, Neurocrit Care. 2008;9:159-166 Incorrect Answer Try Again D. TIGHT GLUCOSE CONTROL BETWEEN 80 AND 110MG/DL IS RECOMMENDED IN CRITICALLY ILL PATIENTS In a large, international, randomized trial where 3016 intensive care patients received intensive-control of blood glucose (target of 81-108 md/dl) vs 3014 patients who received a more conventional glucose management (target < 180 md/dl), investigators found an increased mortality in the intensive-control group of patients (27.5%) compared to the conventional group (24.9%). Despite the negative consequences of hyperglycemia like metabolic acidosis and neuronal cell death, tight glucose control can be harmful. It is more reasonable to keep glucose between 100-150 mg/dl (5.5-8.25mmol/dl) or 80-180mg/dl during the perioperative period. Nice Sugar study investigators, Intensive vs conventional glucose control in critically ill patients, NEJM, 2009;360(13):1283-97 Stutz, Charchaflieh, Postoperative intensive care including head injury and multisystem sequelae, in Cotrell and Young’s Neuroanesthesia, 5th ed. 2010;Mosby Elsevier, PA Sharma D, Perioperative management of adult traumatic brain injury, Anesthesiology clinics, 2012;30:333-346 Correct! To Q5 Back to Q4 B. HYPERGLYCEMIA IS ASSOCIATED WITH POOR OUTCOME AFTER TBI IN CHILDREN. In an effort to understand the relationship between hyperglycemia and severe TBI in children, Smith et al prospectively followed serum glucose levels in children with severe TBI (GCS ≤8) with protocol based care which excluded glucose administration for 48 hours after TBI unless serum glucose <70mg/dL. At >48 hours, these authors found an association between increased serum glucose (>133 mg/dL) and unfavorable outcome, as determined by Glasgow outcome scores at 6 months vs a more favorable outcome in children with glucose <115md/dL. Smith RL, Relationship between hyperglycemia and outcome in children with severe traumatic brain injury, Pediatr Crit Care Med. 2012;13:85-91 Incorrect Answer Try Again C. SEVERE HYPERGLYCEMIA IN CHILDREN WITH TRAUMATIC BRAIN INJURY IS ASSOCIATED WITH INCREASED MORTALITY In a retrospective study of 271 Children admitted to the intensive care with moderate-to severe traumatic brain injury, more children with severe blood glucose elevation (>200mg/dL or 11mmol/L) died compared to children with lower blood glucose levels (<200 mg/dL) Elkon B, et al. Hyperglycemia, and independent risk factor for poor outcome in children with traumatic brain injury. Pediatric Crit Care Med 2014;15(7):623-631 Incorrect Answer Try Again D. ADMINISTRATION OF DEXTROSE CONTAINING INTRAVENOUS SOLUTIONS ARE ROUTINE IN PEDIATRIC TBI PATIENTS Glucose is not routinely added to maintenance fluids in children with TBI due to the frequency and consequences of stress induced hyperglycemia. Agrawal S, Neuroprotective measures in children with traumatic brain injury, World J of Crit Care Med,2016;5(1):36-46 Correct ! Back To Q 1 Back to Q5 End of Set