Neurologic/NM Flashcards
Which of the following modalities will eliminate the risk of developing postoperative myalgias when given prior to administration of succinylcholine?
Perioperative myalgias can cause significant distress in patients. Succinylcholine has an increased risk of causing myalgias in the postoperative period; however, no specific pretreatment has significantly reduced the incidence of myalgias.
A patient reports new onset headache, dizziness, and shortness of breath following benzocaine administration. An arterial blood gas is drawn and fingertip pulse oximetry is measured while the patient is breathing room air:
Room air ABG: pH: 7.27 pCO2: 32 mm Hg PaO2: 100 mm Hg HCO3: 15 mEq/L BE: -10 Calculated SaO2: 100% Pulse oximetry: 86%
If the patient then breathes supplemental oxygen via nonrebreather facemask for 30 minutes, which of the following sets of data would BEST support a diagnosis of methemoglobinemia?
The presence of MetHb forces two-wave pulse oximetry to falsely display an SpO2 of 85-88% regardless of true SaO2 and will cause the calculated SaO2 on an ABG to be falsely high. In general, PaO2 values are unaffected by MetHb and will increase appropriately when supplemental oxygen is given.
You are caring for an 18-year-old patient undergoing urgent exploratory laparotomy for small bowel obstruction secondary to adhesions. An airway cart is obtained prior to induction, which includes multiple airway modalities including jet ventilation, a fiberoptic scope, and a tracheostomy kit. The patient was given propofol and succinylcholine for induction. Following administration of induction medications, the patient develops severe trismus with no other muscle rigidity noted. Vital signs are BP 110/70 mmHg, HR 105 bpm, SpO2 100%, and temperature 37.1 degC. Of the following, which is the MOST appropriate?
patient should be considered a full stomach secondary to their small bowel obstruction. The airway should be secured to prevent pulmonary aspiration. Trismus may resolve, however it can take up to 20 minutes and mask ventilating for that long will increase the risk of pulmonary aspiration. If the patient were to vomit, it would be very difficult to suction and visualize anything with a fiberoptic scope. Attempts should be made to secure the airway by either administering a dose of nondepolarizing agent and intubating or performing a nasal intubation.
A 27-year-old paraplegic from complete transection of the spinal cord at T10 is undergoing laparoscopic cholecystectomy with rocuronium for neuromuscular blockade. Near the end of the procedure, the train-of-four ratio (T4:T1) is measured to be 70% using the right ulnar nerve. If the right posterior tibial nerve is tested instead, which of the following would be the MOST likely response as compared to the ulnar nerve response?
The proliferation of extrajunctional acetylcholine receptors in muscle in paralyzed limbs can lead to an increased response (T4:T1) to peripheral nerve stimulation following non depolarizing neuromuscular blockade compared to a normal non paralyzed limb in the same patient.
Which of the following intravenous anesthetic agents is paired correctly with its effect on cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF)?
Volatile anesthetics at >1 MAC decrease the cerebral metabolic rate of oxygen (CMRO2) and increase cerebral blood flow (CBF). Intravenous anesthetic drugs, except ketamine, lead to parallel reductions in CBF and CMRO2.
In which patient is the use of succinylcholine for induction MOST acceptable?
Succinylcholine causes several side effects, including hyperkalemia in patients with NAChR upregulation. This can occur in patients with upper motor neuron injury such as spinal cord injury, multiple sclerosis, Guillain-Barré, burn victims, prolonged immobilization, as well as many others. Succinylcholine can typically be used in conditions without NAChR upregulation, such as chronic renal failure, myasthenia gravis, and Lambert-Eaton syndrome.
A 45-year old male is brought to the hospital after a motor vehicle accident. He has a Glasgow Coma Scale score of 3 and was intubated in the field. Which of the following statements is TRUE?
Maintenance of cerebral perfusion pressure is exquisitely important when caring for a patient with a traumatic brain injury. Even a single episode of hypotension decreases cerebral perfusion enough to affect outcomes. The CPP value to target lies within the range of 50-70 mm Hg according to current BTF guidelines.
TrueLearn Insight : TBIs are categorized by level of severity: mild, moderate, and severe. A mild TBI is associated with a Glasgow Coma Scale (GCS) score of 13-15 and minimal to no loss of consciousness. A moderate TBI is associated with a GCS of 9-12 and a loss of consciousness of 30 minutes or more. A severe TBI is associated with a GCS of 3-8.
Succinylcholine associated side effects are MOST LIKELY to be seen in which of the following patients?
Patients with multiple sclerosis require careful anesthetic medication planning. The response to neuromuscular blocking agents will be variable based on symptomatology and severity of the disease. It is important to recognize that some patients with multiple sclerosis will be sensitive to succinylcholine, and if administered it could result in a severe hyperkalemic response.
A 10-year-old female is brought to the hospital after sustaining a femur fracture while riding her bicycle. She lives with two parents who smoke and she has hypokalemic periodic paralysis. Which of the following is MOST likely to precipitate an attack of her paralysis?
Patients with hypokalemic periodic paralysis should not be given large amounts of glucose either orally or intravenously. The glucose load will increase serum insulin levels, which will in turn lower serum potassium levels.
Paralytic attacks may be triggered by stress, hypothermia, and strenuous activity. Attacks can also be caused by significant carbohydrate or glucose loads. Hypokalemic periodic paralysis is treated with potassium containing fluid, carbonic anhydrase inhibitors and potassium sparing diuretics.
Which of the following statements about thiopental is TRUE?
The cerebral flow-metabolism relationship and cerebral autoregulation remain intact with the use of thiopental. Thiopental decreases both CBF and CMRO2 by 30% with induction doses and by 50% upon achievement of an isoelectric EEG.
TrueLearn Insight : Burst suppression on EEG is the goal target of reducing CMRO2 during an open cerebral aneurysm clipping. Burst suppression sufficiently indicates depressed CMRO2 while providing predictability of recovery and awakening once the IV anesthetic is turned off.
A 20-year-old male receives metoclopramide in the post-anesthesia care unit for nausea and vomiting following elective knee arthroscopy. Soon after, he develops neck muscle spasms and his head is stuck turned to the left. Which of the following medications is LEAST likely to improve his symptoms?
Treatment options for EPS or acute dystonic reactions from dopamine receptor antagonists include anticholinergics (preferred), benzodiazepines, beta-blockers, antihistamines, dopamine agonists, and alpha-adrenergic agonists. Commonly used anticholinergic agents are benztropine, diphenhydramine, and trihexyphenidyl.
A 19-year-old male is brought to the hospital following an unhelmeted motorcycle accident. In the Emergency Department, he appears to be protecting his airway, opens his eyes only to painful stimuli, and withdraws from painful stimuli but does not localize the stimulus. He moans but is not forming words. He has several lacerations across his left arm and face. What is his Glasgow Coma Scale score?
The GCS is used to quickly assess the severity of a neurological injury. See the above scoring system.
TrueLearn Insight : A mnemonic to remember which category has 4, 5, or 6 points is “eyes, vocal, motors” where the number of letters in each word corresponds to the number of points in that category.
A healthy teenager is undergoing awake arthroscopic shoulder surgery in the sitting (beach chair) position under an interscalene block. He becomes hypotensive and profoundly bradycardic; you surmise he is having a vagal reflex response and appropriately treat him with atropine. Which of the following is the MOST likely location of the receptors for the afferent pathway of this reflex?
The Bezold-Jarisch reflex responds to noxious ventricular stimuli sensed by chemoreceptors and mechanoreceptors within the left ventricular wall by inducing the triad of hypotension, bradycardia, and coronary artery dilatation.
Vagal reflexes causing bradycardia can have several afferent pathways: trigeminal nerve (stretch receptors in extraocular muscles in the oculocardiac reflex), glossopharyngeal nerve (stretch receptors in carotid sinuses and chemoreceptors in carotid bodies), and vagus nerve (stretch receptors in aortic arch and chemoreceptors in ventricular wall).
Which of the following can easily enter the intact blood brain barrier through passive diffusion?
The blood-brain barrier provides protection for the specialized cells of the brain. Because tight regulation needs to occur, certain specialized cells are present which limit the exchange of certain molecules. In general, the passage of substances is predominantly a function of lipid solubility and the presence of active transport systems. Molecules must be small and unionized, not ionized, to passively diffuse through the blood-brain barrier. Small molecules (less than 500 Da) passively diffuse across the blood-brain barrier, not large molecules (>1000 Da).
Use of succinylcholine would be the SAFEST in which of the following scenarios?
Upregulation of extrajunctional acetylcholine receptors occurs with paralysis (stroke, hemiplegia), prolonged bed rest, prolonged neuromuscular blocking drug use, burn injury, and denervation. It can result in hyperkalemia with succinylcholine administration and resistance to nondepolarizing neuromuscular blockers. This effect can be seen as early as 48 hours and last up to 2 years.
