Pharmacology 5 Flashcards
(40 cards)
A 3-year-old boy who aspirated a cherry pit is brought to the operating room for a rigid bronchoscopy. The anesthesiologist plans to do an inhalational induction with sevoflurane. Which of the following statements is the MOST accurate regarding the induction of this child compared to that of a healthy child?
Aspirating a foreign body can result in the obstruction of the right mainstem or a smaller bronchus. This leads to a portion of the lung that is not ventilated, but is perfused. Intrapulmonary shunt will result in a slower inhalational induction. The rise of FA/FI will be less steep (less rapid).
Which of the following choices BEST explains why nalbuphine does not lead to increasing respiratory depression above 30 mg in adults?
Nalbuphine is a mu antagonist and kappa opioid receptor agonist which exhibits a plateau effect for respiratory depression.
You want to administer rocuronium precurarization prior to succinylcholine in an attempt to prevent fasciculations. What is the appropriate dosage?
The recommended precurarization dosage for a nondepolarizing agent is 10% of the ED95, given about 3-5 minutes prior to succinylcholine. Using 10% of the intubating dose (20% of the ED95) is associated with an unacceptably high rate of side effects, including dyspnea in an awake patient.
Use of sugammadex is MOST acceptable for a patient with which of the following characteristics?
Sugammadex is FDA approved for reversal of neuromuscular blockade by rocuronium or vecuronium in adult patients undergoing surgery. It is contraindicated in patients with known hypersensitivity to sugammadex or its components. Other patient populations or situations in which the use of sugammadex is not recommended and/or not FDA approved include: pediatric patients, patients with severe renal failure, reversal of NBDs other than rocuronium and vecuronium, and for reversal following rocuronium or vecuronium administration in ICUs.
TrueLearn Insight : Sugammadex is physically incompatible with ondansetron, ranitidine, and verapamil and should not be co-administered with these medications. If sugammadex and one of the above drugs are to be administered in the same line, the line should be adequately flushed with saline between administration of the two drugs.
A 3-year-old male is brought to the emergency department with shortness of breath. Chest radiograph shows an object lodged in the right mainstem bronchus. The patient is taken to the operating room for removal of the foreign body. Which of the following is MOST accurate regarding induction of anesthesia in this patient compared to a healthy child?
Right to left shunt slows the speed of inhalational induction. This is more obvious in less soluble agents. In the presence of an intrapulmonary shunt, the speed of induction will affect (most to least): Nitrous Oxide > Desflurane > Sevoflurane > Isoflurane > Halothane.
TrueLearn Insight : Endobronchial intubation is another situation that produces a right to left intrapulmonary shunt.
A 33-year-old female with a history of chronic opioid abuse is started on methadone. Which of the following is MOST TRUE regarding management during methadone treatment?
There is high individual patient variability in pharmacokinetics for methadone dosing. Patients on methadone therapy should have slow and careful titration of the drug during initiation of therapy, serial electrocardiograms, and routine urine drug screening. Dose adjustments are rarely needed for patients with renal disease.
TrueLearn Insight : Inhalational anesthetics and ondansetron can also cause QT prolongation. Treatment of Torsades de Pointes is intravenous magnesium.
Which of the following is the MOST accurate statement regarding epidural administration of morphine and clonidine?
Clonidine is an effective analgesic drug. It has a longer epidural effect duration than morphine. When given in combination with morphine, the analgesic effect is enhanced.
Which of the following statements is the MOST accurate regarding intravenous nicardipine usage?
Nicardipine is metabolized by the liver and eliminated via gastrointestinal tract. Renal insufficiency has no effect on nicardipine use. Severe hepatic insufficiency results in significantly prolonged nicardipine half-life.
Nicardipine (intravenous and oral) can cause an increase in heart rate in about 25% of the people. This tachycardia is NOT due to baroreceptor response, rather due to sympathetic activation. Nicardipine decreases systemic vascular resistance, but also increases cardiac contractility
Which of the following drugs must be metabolized to exert its clinical effects?
Codeine is an opiate prodrug whose effects are primarily dependent on metabolism to morphine, which requires the cytochrome P450 enzyme CYP2D6.
TrueLearn Insight : To remember which CYP is most involved with codeine: “coDeine” has 2 letters then D and 6 letters total aside from the D (2D6).
Which of the following will affect the onset of analgesia from local anesthetics the LEAST?
The onset of effect of a local anesthetic is affected by its concentration (higher is faster), lipid solubility (higher is faster), pKa (lower is faster), and environment pH (higher is faster). Anything that increases the concentration or proportion of local anesthetic in its unionized form will speed the onset of analgesia.
Which of the following is LEAST likely to be associated with QT prolongation?
Aprepitant is a neurokinin type 1 (NK1) receptor antagonist and has shown good efficacy for the prevention of vomiting for up to 48 hours postoperatively. Aprepitant has not been shown to cause any changes in ECG, whereas several other antinausea medications such as droperidol, haloperidol, and ondansetron can cause QT prolongation.
For which of the following operations is the use of nitrous oxide MOST appropriate?
Nitrous oxide should be avoided in situations where bowel distention could be particularly hazardous. Both the length of time administered and the concentration of nitrous oxide lead to increasing bowel distention.
TrueLearn Insight : An air-filled endotracheal tube cuff is susceptible to expansion by nitrous oxide. At 75% nitrous oxide a cuff can double or triple in volume causing pressure on the tracheal mucosa. Similarly, nitrous oxide may expand the cuffs of balloon-tipped (e.g. pulmonary artery) catheters. The air expansion is rapid and a doubling of catheter volume may occur within 10 minutes.
Which of the following is a gastrointestinal side effect of glycopyrrolate?
Glycopyrrolate delays gastric emptying, decreases salivary and gastric secretions, increases heart rate, relaxes bronchial smooth muscle, decreases lower esophageal sphincter tone, and causes urinary retention.
Which of the following is the site of action for tirofiban?
Abciximab, eptifibatide, and tirofiban are GP IIb-IIIa receptor inhibitors that prevent platelet aggregation and thrombus formation.
Metoclopramide is contraindicated in which of the following patients?
Metoclopramide is a promotility antiemetic contraindicated in patients with complete bowel obstruction. Combinations involving metoclopramide are not found to reduce PONV to a greater extent than monotherapy. Metoclopramide is a weak antiemetic and at a dose of 10 mg is not effective in reducing the incidence of nausea and vomiting.
TrueLearn Insight : Metoclopramide inhibits plasma cholinesterase and can increase the duration of action of succinylcholine.
Which of the following statements regarding the cardiovascular and respiratory effects of morphine is FALSE?
Morphine reduces preload and afterload. This reduces myocardial oxygen demand and improves coronary perfusion pressures by reducing ventricular EDV and EDP. Morphine has minimal effect on myocardial contractility by itself but may cause myocardial depression when combined with volatile anesthetics. All µ-opioid agonists cause dose-dependent respiratory depression by decreasing the sensitivity of central chemoreceptors to elevated levels of CO2.
TrueLearn Insight : Evoked Potential: Morphine and its active metabolites, morphine-6-glucuronide and morphine-3-glucuronide, are excreted via the kidneys. Morphine-6-glucuronide is a more potent and a longer-lasting opioid agonist than morphine itself. This makes morphine relatively contraindicated in renal failure.
A 64-year-old woman with a history of essential tremor is chronically treated with primidone. She underwent implantation of a deep brain stimulator which was complicated by intracranial hemorrhage. She is intubated and transferred to the ICU. You are considering a midazolam infusion for sedation. Which of the following mechanisms is MOST likely to cause an increased dose requirement of midazolam in this patient?
Chronic administration of barbiturates decreases the duration of action of drugs metabolized by cytochrome p450, such as midazolam
A 56-year-old man with a history of end-stage renal disease undergoes a Whipple procedure for cholangiocarcinoma during which cisatracurium is used for neuromuscular blockade. Which of the following combinations of patient pH and temperature would result in an increased metabolism of cisatracurium?
Cisatracurium undergoes nonenzymatic Hofmann elimination in plasma. The reaction speed is increased with higher pH and higher temperature. As the drug undergoes minimal renal or hepatic metabolism, it is safe to use in patients with significant kidney or liver disease.
Excessive intraoperative fluid administration is BEST avoided in patients receiving which of the following antineoplastic agents?
Several antineoplastic drugs, including doxorubicin, cyclophosphamide, 5-fluorouracil, paclitaxel, and rituximab, are capable of causing cardiac toxicity with resultant heart failure. As with any patient with cardiomyopathy, careful attention must be paid to fluid administration to avoid the complications associated with heart failure, such as pulmonary edema.
Which of the following is a mechanism by which dopamine acts?
Dopamine is a naturally occurring catecholamine that stimulates beta-1 and alpha-1 adrenergic receptors as well as D-1 dopamine receptors, which are primarily located in the renal and mesenteric vasculature. The response to exogenously administered dopamine depends on the dose given. At lower concentrations, dopamine primarily acts on the D-1 dopamine receptors to produce vasodilation of the renal, mesenteric, and coronary vasculature. The main result is an increase in the glomerular filtration rate and renal blood flow. Furthermore, low dose dopamine will result in sodium excretion which will increase urine output.
Higher doses will stimulate the beta-1 receptors to increase release of norepinephrine from sympathetic nerve terminals. The end result is an increase in heart rate, systolic blood pressure, and pulse pressure. At the highest doses, dopamine administration will stimulate alpha-1 receptors which results in peripheral vasoconstriction.
How is 2-chloroprocaine metabolized?
2-chloroprocaine is an ester local anesthetic that is metabolized rapidly by plasma cholinesterase.
What is the most common cause of hypoxemia in a patient using an IV PCA with opioids?
Hypoventilation is the primary cause of hypoxemia in patients receiving opioids.
Minimum alveolar concentration requirements for volatile agents are reduced by which of the following?
Factors that decrease MAC are those that decrease neurotransmission, decrease CNS neurotransmitter levels, or decrease cerebral metabolism including hyponatremia.
TrueLearn Insight : Magnesium administration has a curious effect on anesthetic requirements. Studies have shown that it decreases anesthetic requirements during TIVA. However, the opposite has been shown with volatile anesthetics where it increases MAC. To further confuse the picture, rats who were fed a low magnesium diet (hypomagnesemic) had higher MAC requirements.
What is the expected initial hemodynamic effect after giving dexmedetomidine as a bolus dose of 2 mcg/kg?
A bolus dose of dexmedetomidine has a biphasic hemodynamic response. Initially, dexmedetomidine stimulates peripheral alpha-2 receptors resulting in hypertension and subsequent decrease in heart rate and cardiac output. The peak hypertensive response occurs around three minutes after the bolus dose is given and the blood pressure returns to baseline after around ten minutes. Subsequently, there is a slow decline in blood pressure over the next hour.
