A 44-year-old male is brought to the emergency department by fire and rescue after he was the unrestrained driver in a motor vehicle accident. His wife notes that the patient’s only past medical history is recent development of severe episodes of headache accompanied by sweating and palpitations. She says that these episodes were diagnosed as atypical panic attacks by the patient’s primary care provider, and the patient was started on sertraline and alprazolam. In the trauma bay, the patient’s temperature is 97.6°F (36.4°C), blood pressure is 81/56 mmHg, pulse is 127/min, and respirations are 14/min. He has a Glascow Coma Score (GCS) of 10. He is extremely tender to palpation in the abdomen with rebound and guarding. His skin is cool and clammy, and he has thready peripheral pulses. The patient's Focused Assessment with Sonography for Trauma (FAST) exam reveals bleeding in the perisplenic space, and he is taken for emergency laparotomy. He is found to have a ruptured spleen, and his spleen is removed. During manipulation of the bowel, the patient’s temperature is 97.8°F (36.6°C), blood pressure is 246/124 mmHg, and pulse is 104/min. The patient is administered intravenous labetalol, but his blood pressure continues to worsen. The patient dies during the surgery.
Which of the following medications would most likely have prevented this outcome?
Q572
A 72-year-old Caucasian female presents to the emergency department with complaints of a new-onset, right-sided throbbing headache which becomes markedly worse when eating. The daughter also reports that her mother has recently had difficulties with performing daily activities, such as climbing stairs or standing up. Past medical history is significant for a lower extremity deep vein thrombosis. The blood pressure is 124/78 mm Hg, the heart rate is 72/min, and the respiratory rate is 15/min. The physical examination is unremarkable except for the right visual field defect. Laboratory results are presented below:
Hemoglobin 11.3 g/dL
Hematocrit 37.7%
Leukocyte count 6,200/mm3
Mean corpuscular volume 82.2 μm3
Platelet count 200,000/mm3
Erythrocyte sedimentation rate 75 mm/h
C-reactive protein 50 mg/dL
Which of the following medications would be most beneficial for this patient?
Q573
A 66-year-old woman presents to the emergency department with a throbbing headache. She states that the pain is worse when eating and is localized over the right side of her head. Review of systems is only notable for some blurry vision in the right eye which is slightly worse currently. The patient's past medical history is notable only for chronic pain in her muscles and joints for which she has been taking ibuprofen. Her temperature is 99.1°F (37.3°C), blood pressure is 144/89 mmHg, pulse is 87/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical examination is significant for tenderness to palpation over the right temporal region. Which of the following is the best initial step in management?
Q574
A 45-year-old man comes to the physician because of intermittent lower back pain for 1 week. His symptoms began shortly after lifting heavy boxes at work. He has not had any fever, chills, or weight loss. He has a history of peptic ulcer disease. He does not smoke or drink alcohol. His vital signs are within normal limits. Examination shows mild paraspinal lumbar tenderness. Neurologic examination shows no focal findings. An x-ray of the spine shows no abnormalities. Which of the following is the most appropriate initial pharmacotherapy?
Q575
A 26-year-old gravida 4 para 1 presents to the emergency department with sudden severe abdominal pain and mild vaginal bleeding. Her last menstrual period was 12 weeks ago. She describes her pain as similar to uterine contractions. She has a history of 2 spontaneous abortions in the first trimester. She is not complaining of dizziness or dyspnea. On physical examination, the temperature is 36.9°C (98.4°F), the blood pressure is 120/85 mm Hg, the pulse is 95/min, and the respiratory rate is 17/min. The pelvic examination reveals mild active bleeding and an open cervical os. There are no clots. Transvaginal ultrasound reveals a fetus with no cardiac activity. She is counseled about the findings and the options are discussed. She requests to attempt medical management with mifepristone before progressing to surgical intervention. Which of the following describes the main mechanism of action for mifepristone?
Q576
A 28-year-old man presents to the emergency department with vomiting. He states that he has experienced severe vomiting starting last night that has not been improving. He states that his symptoms improve with hot showers. The patient has presented to the emergency department with a similar complaint several times in the past as well as for intravenous drug abuse. His temperature is 99.5°F (37.5°C), blood pressure is 127/68 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 98% on room air. Physical exam is deferred as the patient is actively vomiting. Which of the following is associated with the most likely diagnosis?
Q577
A 12-year-old female presents to your office complaining of several brief episodes of shortness of breath of varying severity. Which of the following substances would lead to a decrease in FEV1 of 20% if the patient has asthma?
Q578
While walking through a park with his wife, a 51-year-old man with type 2 diabetes mellitus develops nausea, sweating, pallor, and palpitations. For the past 3 weeks, he has been trying to lose weight and has adjusted his diet and activity level. He eats a low-carb diet and swims 3 times a week. The man returned home from a training session 2 hours ago. Current medications include basal insulin and metformin. Shortly before his wife returns from their car with his emergency medication kit, he becomes unconscious. Administration of which of the following is the most appropriate next step in management?
Q579
A 66-year-old man with coronary artery disease and hypertension comes to the emergency department because of intermittent retrosternal chest pain, lightheadedness, and palpitations. He has smoked one pack of cigarettes daily for 39 years. His pulse is 140/min and irregularly irregular, respirations are 20/min, and blood pressure is 108/60 mm Hg. An ECG shows an irregular, narrow-complex tachycardia with absent P waves. A drug with which of the following mechanisms of action is most likely to be effective in the long-term prevention of embolic stroke in this patient?
Q580
A 67-year-old male presents to the emergency department with sudden onset shortness of breath and epigastric pain. The patient has a past medical history of GERD, obesity, diabetes mellitus type II, anxiety, glaucoma, and irritable bowel syndrome. His current medications include omeprazole, insulin, metformin, lisinopril, and clonazepam as needed. The patient's temperature is 99.5°F (37.5°C), pulse is 112/min, blood pressure is 90/70 mmHg, respirations are 18/min, and oxygen saturation is 95% on room air. On physical exam the patient's lungs are clear to auscultation bilaterally. JVD is notable and cardiac auscultation is not revealing. An EKG is obtained in the emergency department. The patient is given a bolus of fluids and his pulse becomes 80/min with a blood pressure of 105/75 mmHg. The patient is then started on beta-blockers, oxygen, nitroglycerin, morphine, IV fluids, and aspirin. Repeat vitals demonstrate a blood pressure of 80/65 mmHg. Which of the following is the best explanation of this patient's current vital signs?
Autonomic/CV Drugs US Medical PG Practice Questions and MCQs
Question 571: A 44-year-old male is brought to the emergency department by fire and rescue after he was the unrestrained driver in a motor vehicle accident. His wife notes that the patient’s only past medical history is recent development of severe episodes of headache accompanied by sweating and palpitations. She says that these episodes were diagnosed as atypical panic attacks by the patient’s primary care provider, and the patient was started on sertraline and alprazolam. In the trauma bay, the patient’s temperature is 97.6°F (36.4°C), blood pressure is 81/56 mmHg, pulse is 127/min, and respirations are 14/min. He has a Glascow Coma Score (GCS) of 10. He is extremely tender to palpation in the abdomen with rebound and guarding. His skin is cool and clammy, and he has thready peripheral pulses. The patient's Focused Assessment with Sonography for Trauma (FAST) exam reveals bleeding in the perisplenic space, and he is taken for emergency laparotomy. He is found to have a ruptured spleen, and his spleen is removed. During manipulation of the bowel, the patient’s temperature is 97.8°F (36.6°C), blood pressure is 246/124 mmHg, and pulse is 104/min. The patient is administered intravenous labetalol, but his blood pressure continues to worsen. The patient dies during the surgery.
Which of the following medications would most likely have prevented this outcome?
A. Lorazepam
B. Propylthiouracil
C. Phenoxybenzamine (Correct Answer)
D. Dantrolene
E. Phentolamine
Explanation: ***Phenoxybenzamine***
- This patient likely had an undiagnosed **pheochromocytoma**, which is a **catecholamine-secreting tumor**. The severe labile hypertension during surgery, unresponsive to labetalol, is a classic sign of a catecholamine surge.
- **Phenoxybenzamine** is an **irreversible alpha-adrenergic blocker** that would have been used pre-operatively to control blood pressure and prevent such a hypertensive crisis by blocking the effects of excess catecholamines.
*Lorazepam*
- **Lorazepam** is a **benzodiazepine** used for anxiety and seizure control. While it might have helped to calm the patient or manage panic, it would not address the underlying physiological cause of the hypertensive crisis associated with an endocrine tumor.
- Its effects on blood pressure are generally mild and would not counteract the massive catecholamine release seen in a pheochromocytoma.
*Propylthiouracil*
- **Propylthiouracil** is an **antithyroid medication** used to treat **hyperthyroidism**. There is no indication of thyroid dysfunction in this patient's presentation.
- The symptoms of palpitations and sweating are common to both pheochromocytoma and hyperthyroidism, but the rapid, extreme hypertensive crisis points away from thyroid storm and towards a catecholamine-secreting tumor.
*Dantrolene*
- **Dantrolene** is a **skeletal muscle relaxant** primarily used to treat and prevent **malignant hyperthermia**.
- There is no evidence in the clinical presentation to suggest malignant hyperthermia as the cause of this patient's deterioration; the extreme hypertension is the primary issue.
*Phentolamine*
- **Phentolamine** is a **reversible alpha-adrenergic blocker** used to manage hypertensive crises, particularly those due to pheochromocytoma or monoamine oxidase inhibitor interactions.
- While phentolamine could be used during a crisis, **phenoxybenzamine** is preferred for *pre-operative preparation* due to its longer-acting and irreversible blockade, preventing the crisis more effectively when surgery is anticipated for pheochromocytoma.
Question 572: A 72-year-old Caucasian female presents to the emergency department with complaints of a new-onset, right-sided throbbing headache which becomes markedly worse when eating. The daughter also reports that her mother has recently had difficulties with performing daily activities, such as climbing stairs or standing up. Past medical history is significant for a lower extremity deep vein thrombosis. The blood pressure is 124/78 mm Hg, the heart rate is 72/min, and the respiratory rate is 15/min. The physical examination is unremarkable except for the right visual field defect. Laboratory results are presented below:
Hemoglobin 11.3 g/dL
Hematocrit 37.7%
Leukocyte count 6,200/mm3
Mean corpuscular volume 82.2 μm3
Platelet count 200,000/mm3
Erythrocyte sedimentation rate 75 mm/h
C-reactive protein 50 mg/dL
Which of the following medications would be most beneficial for this patient?
A. Prednisolone (Correct Answer)
B. Low-molecular-weight heparin
C. Gabapentin
D. Methotrexate
E. Celecoxib
Explanation: ***Prednisolone***
- The patient's symptoms (new-onset headache, jaw claudication, visual field defect) and elevated inflammatory markers (**ESR, CRP**) are highly suggestive of **giant cell arteritis (GCA)**, which can lead to irreversible vision loss.
- **High-dose corticosteroids** like prednisolone are the mainstay of treatment for GCA to prevent complications such as blindness and stroke.
*Low-molecular-weight heparin*
- This medication is primarily used for the **prevention and treatment of thromboembolic events**, such as deep vein thrombosis (DVT) or pulmonary embolism.
- While the patient has a history of DVT, there are no current signs or symptoms indicating an acute thromboembolic event requiring immediate anticoagulation.
*Gabapentin*
- This drug is an **antiepileptic** and is commonly used to treat **neuropathic pain**, such as postherpetic neuralgia or diabetic neuropathy.
- The patient's headache is characteristic of an inflammatory vascular process, not neuropathic pain.
*Methotrexate*
- Methotrexate is a **disease-modifying antirheumatic drug (DMARD)** primarily used in the treatment of various autoimmune conditions, including **rheumatoid arthritis** and **psoriasis**.
- While it can be used as a steroid-sparing agent in some vasculitides, it is not the initial or most effective treatment for acute GCA and does not rapidly prevent acute ischemic complications.
*Celecoxib*
- Celecoxib is a **selective COX-2 inhibitor** (a type of NSAID) used for pain and inflammation, particularly in conditions like osteoarthritis and rheumatoid arthritis.
- While it can reduce inflammation, it is **insufficient to rapidly control the systemic inflammation** and prevent the severe ischemic complications associated with GCA.
Question 573: A 66-year-old woman presents to the emergency department with a throbbing headache. She states that the pain is worse when eating and is localized over the right side of her head. Review of systems is only notable for some blurry vision in the right eye which is slightly worse currently. The patient's past medical history is notable only for chronic pain in her muscles and joints for which she has been taking ibuprofen. Her temperature is 99.1°F (37.3°C), blood pressure is 144/89 mmHg, pulse is 87/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical examination is significant for tenderness to palpation over the right temporal region. Which of the following is the best initial step in management?
A. Methylprednisolone (Correct Answer)
B. Ibuprofen and acetaminophen
C. MRI head
D. CT head
E. 100% oxygen
Explanation: ***Methylprednisolone***
- The patient presents with classic symptoms of **giant cell arteritis (GCA)**, including a new-onset, unilateral, throbbing headache, jaw claudication (pain worse with eating), temporal artery tenderness, and new or acutely worsening **vision changes**.
- Prompt initiation of **high-dose corticosteroids** (like methylprednisolone) is crucial to prevent irreversible vision loss and other ischemic complications.
*Ibuprofen and acetaminophen*
- These medications are **NSAIDs** and **analgesics** that primarily treat pain and inflammation, but they do not address the underlying acute vasculitis in GCA.
- They will not prevent the progression of **ischemic damage** to the optic nerve or other affected arteries.
*MRI head*
- An **MRI head** is not the initial step in management for suspected GCA, as it is primarily used to evaluate for other intracranial pathologies like stroke or tumor, or for chronic changes.
- While it can sometimes show **vessel wall edema** in GCA, it is not as urgent as starting steroids and does not replace the immediate need for treatment.
*CT head*
- A **CT head** is primarily used to rule out acute intracranial emergencies such as hemorrhage or large strokes.
- It is generally **not useful** for diagnosing GCA or detecting inflammation of vessel walls, making it an inappropriate initial step given the patient's symptoms.
*100% oxygen*
- **100% oxygen** is a primary treatment for **cluster headaches**, which present with unilateral pain, but typically include autonomic symptoms like lacrimation, rhinorrhea, or ptosis, and are usually much shorter in duration.
- It has **no role** in the management of GCA, which is an inflammatory vasculitis.
Question 574: A 45-year-old man comes to the physician because of intermittent lower back pain for 1 week. His symptoms began shortly after lifting heavy boxes at work. He has not had any fever, chills, or weight loss. He has a history of peptic ulcer disease. He does not smoke or drink alcohol. His vital signs are within normal limits. Examination shows mild paraspinal lumbar tenderness. Neurologic examination shows no focal findings. An x-ray of the spine shows no abnormalities. Which of the following is the most appropriate initial pharmacotherapy?
A. Aspirin
B. Ibuprofen
C. Naproxen
D. Oxycodone
E. Acetaminophen (Correct Answer)
Explanation: ***Acetaminophen***
- Acetaminophen is the **initial pharmacotherapy of choice** for acute low back pain due to its efficacy and favorable side effect profile, especially in patients with a history of peptic ulcer disease who should avoid NSAIDs.
- It provides **analgesia** by inhibiting prostaglandin synthesis in the central nervous system, helping to alleviate musculoskeletal pain without the gastrointestinal risks associated with NSAIDs.
*Aspirin*
- Aspirin is an **NSAID** and would be contraindicated in this patient due to his history of **peptic ulcer disease**, as it increases the risk of gastrointestinal bleeding and ulcer exacerbation.
- While it has analgesic properties, its **antiplatelet effects** and gastrointestinal side effects make it unsuitable as a first-line treatment in this specific clinical context.
*Ibuprofen*
- Ibuprofen is another **NSAID** which, like aspirin, carries a significant risk of **gastrointestinal irritation** and ulceration.
- Its use is **contraindicated** in patients with a history of peptic ulcer disease, making it an inappropriate initial choice for this patient's back pain.
*Naproxen*
- Naproxen is also an **NSAID** and shares the same contraindication as ibuprofen and aspirin in patients with a history of **peptic ulcer disease**.
- Its mechanism of action involves inhibiting cyclooxygenase (COX-1 and COX-2) enzymes, which leads to reduced prostaglandin synthesis but also increased risk of **gastric mucosal damage**.
*Oxycodone*
- Oxycodone is an **opioid analgesic** and is generally reserved for severe pain that is not adequately controlled by non-opioid medications. Given the patient's presentation of **mild paraspinal tenderness** and no focal neurological deficits, it would be an excessive initial choice.
- The use of opioids carries risks of **addiction**, constipation, and sedation, and it is not recommended as a first-line therapy for acute, non-severe low back pain.
Question 575: A 26-year-old gravida 4 para 1 presents to the emergency department with sudden severe abdominal pain and mild vaginal bleeding. Her last menstrual period was 12 weeks ago. She describes her pain as similar to uterine contractions. She has a history of 2 spontaneous abortions in the first trimester. She is not complaining of dizziness or dyspnea. On physical examination, the temperature is 36.9°C (98.4°F), the blood pressure is 120/85 mm Hg, the pulse is 95/min, and the respiratory rate is 17/min. The pelvic examination reveals mild active bleeding and an open cervical os. There are no clots. Transvaginal ultrasound reveals a fetus with no cardiac activity. She is counseled about the findings and the options are discussed. She requests to attempt medical management with mifepristone before progressing to surgical intervention. Which of the following describes the main mechanism of action for mifepristone?
A. Interferes with cell growth in rapidly dividing cells
B. Increase myometrial sensitivity to contractions and induce decidual breakdown (Correct Answer)
C. Induce teratogenesis in the fetus
D. Induce cervical dilation
E. Interferes with placental blood supply to the fetus
Explanation: ***Increase myometrial sensitivity to contractions and induced decidual breakdown***
- **Mifepristone** acts primarily as a **progesterone receptor antagonist**, blocking progesterone's effects.
- This blockade leads to **decidual breakdown**, increased uterine contractility, and increased sensitivity of the myometrium to prostaglandins, facilitating expulsion of uterine contents.
*Interferes with cell growth in rapidly dividing cells*
- This mechanism describes **chemotherapeutic agents** like methotrexate, which targets rapidly dividing cells.
- **Mifepristone** does not interfere with cell growth in this manner; its action is receptor-mediated.
*Induce teratogenesis in the fetus*
- While mifepristone can affect fetal development by terminating a pregnancy, its primary mechanism of action is **not directly teratogenesis** (the induction of birth defects).
- Its purpose is to induce abortion or miscarriage, not to cause malformations in a continuing pregnancy.
*Induce cervical dilation*
- While cervical dilation occurs as a consequence of the abortion process facilitated by mifepristone, it is not the **primary mechanism of action** of the drug itself.
- Cervical dilation is often secondary to uterine contractions and the release of prostaglandins, which are downstream effects of mifepristone.
*Interferes with placental blood supply to the fetus*
- **Mifepristone's** main action is not directly on the placental blood supply; rather, it affects the **uterine lining and myometrial activity**.
- The disruption of pregnancy by mifepristone leads to secondary effects on the placenta and fetal viability, but it doesn't primarily block blood flow.
Question 576: A 28-year-old man presents to the emergency department with vomiting. He states that he has experienced severe vomiting starting last night that has not been improving. He states that his symptoms improve with hot showers. The patient has presented to the emergency department with a similar complaint several times in the past as well as for intravenous drug abuse. His temperature is 99.5°F (37.5°C), blood pressure is 127/68 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 98% on room air. Physical exam is deferred as the patient is actively vomiting. Which of the following is associated with the most likely diagnosis?
A. Viral gastroenteritis
B. Marijuana use (Correct Answer)
C. Substance withdrawal
D. Alcohol use
E. Toxin ingestion
Explanation: ***Marijuana use***
- The patient's history of recurrent vomiting, improvement with hot showers, and a history of intravenous drug abuse are highly suggestive of **cannabinoid hyperemesis syndrome (CHS)**. **Marijuana use** is directly associated with CHS, which presents with cyclical vomiting in chronic cannabis users.
- While the patient has a history of intravenous drug use, the specific pattern of recurrent vomiting relieved by hot showers points strongly towards **CHS**, which is caused by long-term cannabis use.
*Viral gastroenteritis*
- Although **viral gastroenteritis** can cause severe vomiting, it typically resolves within a few days and does not usually present as a recurrent issue relieved by hot showers.
- This condition does not explain the patient's history of multiple similar presentations or the specific alleviating factor of hot showers.
*Substance withdrawal*
- While some **substance withdrawal syndromes** can cause nausea and vomiting, the characteristic relief with hot showers is not typical for withdrawal symptoms.
- The patient's symptoms are more indicative of a syndrome directly linked to substance use rather than withdrawal.
*Alcohol use*
- **Alcohol use** can cause vomiting in episodes of acute intoxication or withdrawal; however, repeated episodes of severe vomiting relieved specifically by hot showers are not a classic presentation of alcohol-related vomiting.
- There is no specific mention of alcohol abuse in the patient's history as a cause for these symptoms.
*Toxin ingestion*
- **Toxin ingestion** can indeed cause severe vomiting, but it would not typically be a recurring problem that improves with hot showers.
- The recurrent nature and specific relieving factor point away from a one-time toxic exposure.
Question 577: A 12-year-old female presents to your office complaining of several brief episodes of shortness of breath of varying severity. Which of the following substances would lead to a decrease in FEV1 of 20% if the patient has asthma?
A. Methacholine (Correct Answer)
B. Epinephrine
C. Albuterol
D. Norepinephrine
E. Ipratropium
Explanation: ***Methacholine***
- **Methacholine** is a **cholinergic agonist** that induces **bronchoconstriction**, and a 20% decrease in FEV1 is diagnostic for **asthma** in a methacholine challenge test.
- This substance is used specifically to test for **airway hyperresponsiveness**, a hallmark of asthma.
*Epinephrine*
- **Epinephrine** is a **sympathomimetic** that causes **bronchodilation**, which would increase FEV1 rather than decrease it.
- It acts on **beta-2 adrenergic receptors** in the lungs to relax airway smooth muscle.
*Albuterol*
- **Albuterol** is a **short-acting beta-2 agonist (SABA)** used as a rescue inhaler for asthma, leading to **bronchodilation**.
- It would improve FEV1 by relaxing airway smooth muscle, not decrease it.
*Norepinephrine*
- **Norepinephrine** primarily acts on **alpha-adrenergic receptors** and has less potent beta-2 agonist effects compared to epinephrine.
- While it can cause some bronchodilation, it is not used in asthma diagnosis or treatment in this context and would not cause a 20% FEV1 decrease.
*Ipratropium*
- **Ipratropium** is an **anticholinergic bronchodilator** that blocks muscarinic receptors, causing relaxation of airway smooth muscle.
- It would lead to an increase in FEV1, not a decrease, and is primarily used in COPD and some asthma cases.
Question 578: While walking through a park with his wife, a 51-year-old man with type 2 diabetes mellitus develops nausea, sweating, pallor, and palpitations. For the past 3 weeks, he has been trying to lose weight and has adjusted his diet and activity level. He eats a low-carb diet and swims 3 times a week. The man returned home from a training session 2 hours ago. Current medications include basal insulin and metformin. Shortly before his wife returns from their car with his emergency medication kit, he becomes unconscious. Administration of which of the following is the most appropriate next step in management?
A. Sublingual nitroglycerine
B. Oral glucose
C. Intramuscular glucagon (Correct Answer)
D. Rectal lorazepam
E. Intra-arterial dextrose
Explanation: ***Intramuscular glucagon***
- This patient is experiencing severe **hypoglycemia** (nausea, sweating, pallor, palpitations, unconsciousness) exacerbated by his weight loss efforts, diet, and recent exercise while on insulin and metformin. As he is unconscious and cannot take oral glucose, **intramuscular glucagon** is the most appropriate emergency treatment to raise blood glucose levels in this pre-hospital setting.
- **Glucagon** mobilizes glucose from the liver by stimulating hepatic glycogenolysis, making it vital when oral intake is compromised due to altered consciousness and IV access is not immediately available.
*Sublingual nitroglycerine*
- **Nitroglycerine** is used for chest pain suspected to be angina or myocardial infarction, not for hypoglycemia.
- Administering nitroglycerine in a hypoglycemic patient could cause **vasodilation** and further lower blood pressure, potentially worsening their condition.
*Oral glucose*
- While oral glucose is the primary treatment for mild to moderate hypoglycemia, this patient is **unconscious** and therefore cannot safely swallow.
- Giving oral substances to an unconscious person risks **aspiration pneumonia** and choking.
*Rectal lorazepam*
- **Lorazepam** is an anxiolytic and anticonvulsant, used primarily to treat seizures or severe anxiety.
- It does not address the underlying hypoglycemia and could further **depress the central nervous system**, worsening the patient's altered mental status.
*Intra-arterial dextrose*
- **Intra-arterial dextrose** is not a standard or safe route for treating hypoglycemia. While **intravenous dextrose** would be appropriate in a hospital setting, it is not available in this pre-hospital emergency scenario.
- Administering substances intra-arterially can cause severe damage, including **arterial spasm**, thrombosis, and tissue necrosis.
Question 579: A 66-year-old man with coronary artery disease and hypertension comes to the emergency department because of intermittent retrosternal chest pain, lightheadedness, and palpitations. He has smoked one pack of cigarettes daily for 39 years. His pulse is 140/min and irregularly irregular, respirations are 20/min, and blood pressure is 108/60 mm Hg. An ECG shows an irregular, narrow-complex tachycardia with absent P waves. A drug with which of the following mechanisms of action is most likely to be effective in the long-term prevention of embolic stroke in this patient?
A. Irreversible inhibition of cyclooxygenase
B. Interference with carboxylation of glutamate residues (Correct Answer)
C. Binding and activation of antithrombin III
D. Irreversible blockade of adenosine diphosphate receptors
E. Activation of the conversion of plasminogen to plasmin
Explanation: ***Interference with carboxylation of glutamate residues***
- The patient's presentation with **irregularly irregular pulse**, **narrow-complex tachycardia**, and **absent P waves** on ECG is highly suggestive of **atrial fibrillation**.
- **Atrial fibrillation** increases the risk of **thromboembolic stroke**, and long-term prevention requires **anticoagulation**.
- This mechanism describes **warfarin**, a vitamin K antagonist that inhibits the **carboxylation of glutamate residues** in clotting factors (II, VII, IX, X), preventing their activation.
- While **direct oral anticoagulants (DOACs)** are now often preferred as first-line therapy, warfarin remains an effective and widely used option for stroke prevention in atrial fibrillation, particularly when DOACs are contraindicated or unavailable.
*Irreversible inhibition of cyclooxygenase*
- This mechanism describes **aspirin**, an **antiplatelet agent**.
- While aspirin provides some cardiovascular protection, it is **significantly less effective than anticoagulants** like warfarin or DOACs for stroke prevention in patients with atrial fibrillation.
- Antiplatelet agents alone are generally reserved for patients who cannot tolerate anticoagulation.
*Binding and activation of antithrombin III*
- This mechanism is characteristic of **unfractionated heparin** and **low molecular weight heparins (LMWH)**.
- These agents are primarily used for **acute anticoagulation** (e.g., bridging therapy) and require parenteral administration.
- They are not suitable for long-term oral stroke prevention in atrial fibrillation.
*Irreversible blockade of adenosine diphosphate receptors*
- This mechanism describes **P2Y12 inhibitors** like clopidogrel, prasugrel, and ticagrelor, which are **antiplatelet agents**.
- Like aspirin, P2Y12 inhibitors are **not sufficient as monotherapy** for stroke prevention in atrial fibrillation.
- They are more commonly used in acute coronary syndromes, after percutaneous coronary intervention, or in dual antiplatelet therapy.
*Activation of the conversion of plasminogen to plasmin*
- This mechanism describes **thrombolytic agents** (e.g., tissue plasminogen activator - tPA, alteplase), which are used to **dissolve existing clots** in acute scenarios like ischemic stroke or ST-elevation myocardial infarction.
- They are not used for long-term prevention of embolic stroke due to their **significant bleeding risk** and lack of prophylactic benefit.
Question 580: A 67-year-old male presents to the emergency department with sudden onset shortness of breath and epigastric pain. The patient has a past medical history of GERD, obesity, diabetes mellitus type II, anxiety, glaucoma, and irritable bowel syndrome. His current medications include omeprazole, insulin, metformin, lisinopril, and clonazepam as needed. The patient's temperature is 99.5°F (37.5°C), pulse is 112/min, blood pressure is 90/70 mmHg, respirations are 18/min, and oxygen saturation is 95% on room air. On physical exam the patient's lungs are clear to auscultation bilaterally. JVD is notable and cardiac auscultation is not revealing. An EKG is obtained in the emergency department. The patient is given a bolus of fluids and his pulse becomes 80/min with a blood pressure of 105/75 mmHg. The patient is then started on beta-blockers, oxygen, nitroglycerin, morphine, IV fluids, and aspirin. Repeat vitals demonstrate a blood pressure of 80/65 mmHg. Which of the following is the best explanation of this patient's current vital signs?
A. Increased cGMP (Correct Answer)
B. Beta-adrenergic blockade
C. Left ventricular failure
D. Fluid overload
E. Ventricular free wall rupture
Explanation: ***Increased cGMP***
- The administration of **nitroglycerin** leads to increased cGMP, which causes **vasodilation** and can result in **hypotension**, especially in patients with **preload-dependent conditions** like right ventricular infarction.
- The patient's initial excellent response to fluids then subsequent hypotension after vasodilators suggests that the nitroglycerin exacerbated a **preload-dependent state**.
*Beta-adrenergic blockade*
- While beta-blockers can *decrease* **blood pressure** and **heart rate**, the dramatic drop in blood pressure here is more consistent with a strong **vasodilatory effect** from **nitroglycerin**, particularly in the context of the patient's presentation.
- Beta-blockers primarily reduce **cardiac output** by decreasing myocardial contractility and heart rate but are less likely to cause such profound hypotension in this acute setting without significant underlying cardiac dysfunction.
*Left ventricular failure*
- **Left ventricular failure** would typically present with **pulmonary congestion** (e.g., crackles on auscultation), which is absent in this patient with clear lung sounds.
- While heart failure can lead to hypotension, the patient's initial improvement with fluids and then hypotension *after* nitroglycerin points away from primary left ventricular failure as the cause of this specific vital sign change.
*Fluid overload*
- The patient's initial improvement with a fluid bolus and the presence of **JVD** suggest **hypovolemia** or **right ventricular dysfunction**, where cardiac output is preload-dependent.
- **Fluid overload** itself would typically cause a *rise* in blood pressure (unless in cardiogenic shock), not a drop to 80/65 mmHg after therapeutic interventions.
*Ventricular free wall rupture*
- **Ventricular free wall rupture** is a catastrophic complication of myocardial infarction that typically presents with **sudden cardiogenic shock**, **cardiac tamponade**, and rapid clinical deterioration.
- While possible in an MI setting, the patient's temporary improvement with fluids and subsequent hypotension after nitroglycerin make a free wall rupture less likely to be the *best* explanation for the specific vital sign changes observed.