Acute Care US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Acute Care. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Acute Care US Medical PG Question 1: A scientist in Chicago is studying a new blood test to detect Ab to EBV with increased sensitivity and specificity. So far, her best attempt at creating such an exam reached 82% sensitivity and 88% specificity. She is hoping to increase these numbers by at least 2 percent for each value. After several years of work, she believes that she has actually managed to reach a sensitivity and specificity much greater than what she had originally hoped for. She travels to China to begin testing her newest blood test. She finds 2,000 patients who are willing to participate in her study. Of the 2,000 patients, 1,200 of them are known to be infected with EBV. The scientist tests these 1,200 patients' blood and finds that only 120 of them tested negative with her new exam. Of the patients who are known to be EBV-free, only 20 of them tested positive. Given these results, which of the following correlates with the exam's specificity?
- A. 82%
- B. 90%
- C. 84%
- D. 86%
- E. 98% (Correct Answer)
Acute Care Explanation: ***98%***
- **Specificity** measures the proportion of **true negatives** among all actual negatives.
- In this case, 800 patients are known to be EBV-free (actual negatives), and 20 of them tested positive (false positives). This means 800 - 20 = 780 tested negative (true negatives). Specificity = (780 / 800) * 100% = **98%**.
*82%*
- This value represents the *original sensitivity* before the scientist’s new attempts to improve the test.
- It does not reflect the *newly calculated specificity* based on the provided data.
*90%*
- This value represents the *newly calculated sensitivity* of the test, not the specificity.
- Out of 1200 EBV-infected patients, 120 tested negative (false negatives), meaning 1080 tested positive (true positives). Sensitivity = (1080 / 1200) * 100% = 90%.
*84%*
- This percentage is not directly derived from the information given for either sensitivity or specificity after the new test results.
- It does not correspond to any of the calculated values for the new test's performance.
*86%*
- This percentage is not directly derived from the information given for either sensitivity or specificity after the new test results.
- It does not correspond to any of the calculated values for the new test's performance.
Acute Care US Medical PG Question 2: A 25-year-old man is brought to the emergency department 3 hours after rescuing babies and puppies from a burning daycare center. He complains of headache and nausea, which he attributes to running. He is breathing comfortably. What is another likely finding in this patient?
- A. Oxygen saturation of 86% on pulse oximetry
- B. Low blood lactate levels
- C. Arterial oxygen partial pressure of 20 mmHg
- D. Oxygen saturation of 99% on pulse oximetry
- E. Cherry red facial appearance (Correct Answer)
Acute Care Explanation: ***Cherry red facial appearance***
- The patient's presentation after being in a burning building strongly suggests **carbon monoxide (CO) poisoning**. CO binds to hemoglobin with higher affinity than oxygen, forming **carboxyhemoglobin**, which gives the skin and mucous membranes a characteristic **cherry-red (plethoric) appearance**, though this is often only seen in severe cases or post-mortem.
- Other symptoms like **headache and nausea** are classic for CO poisoning, often mistaken for other mild ailments or exertion.
*Oxygen saturation of 86% on pulse oximetry*
- While a low oxygen saturation is concerning, **pulse oximetry readings are unreliable in carbon monoxide poisoning** because standard pulse oximeters cannot differentiate between oxyhemoglobin and carboxyhemoglobin.
- A patient with significant CO poisoning can have a high pulse oximetry reading even with severe hypoxemia at the tissue level, making this an unlikely and misleading finding.
*Low blood lactate levels*
- **Carbon monoxide poisoning** leads to **tissue hypoxia**, which switches cellular metabolism from aerobic to anaerobic glycolysis.
- This results in the overproduction of **lactate**, leading to **elevated blood lactate levels**, not low levels.
*Arterial oxygen partial pressure of 20 mmHg*
- A **PaO2 of 20 mmHg** is severely low and would indicate extreme hypoxemia, which would likely present with significant respiratory distress or altered mental status, and a pulse oximetry reading would be reflective of this severe hypoxemia.
- In **carbon monoxide poisoning**, the PaO2 is typically normal because oxygen can still dissolve in the plasma, but its transport and offloading are impaired by carboxyhemoglobin.
*Oxygen saturation of 99% on pulse oximetry*
- A pulse oximeter measures the percentage of hemoglobin saturated with oxygen. However, it cannot distinguish between **oxyhemoglobin** and **carboxyhemoglobin**.
- Therefore, in CO poisoning, pulse oximetry may give a **falsely high or normal reading (e.g., 99%)**, even when the patient is severely hypoxic due to CO.
Acute Care US Medical PG Question 3: A 40-year-old Caucasian male presents to the emergency room after being shot in the arm in a hunting accident. His shirt is soaked through with blood. He has a blood pressure of 65/40, a heart rate of 122, and his skin is pale, cool to the touch, and moist. This patient is most likely experiencing all of the following EXCEPT:
- A. Decreased sarcomere length in the myocardium
- B. Increased stroke volume (Correct Answer)
- C. Confusion and irritability
- D. Decreased preload
- E. Increased thromboxane A2
Acute Care Explanation: ***Increased stroke volume***
- The patient is experiencing **hypovolemic shock** due to significant blood loss, meaning their **cardiac output** is severely compromised.
- In shock, the heart attempts to compensate by increasing **heart rate**, but **stroke volume** is typically decreased due to reduced **preload**.
*Decreased sarcomere length in the myocardium*
- In situations of significant blood loss and **decreased preload**, there is less venous return to the heart, leading to reduced end-diastolic volume.
- According to the **Frank-Starling law**, reduced end-diastolic volume results in shorter initial sarcomere length, which reduces the force of contraction and thus, **stroke volume**.
*Confusion and irritability*
- **Hypovolemic shock** leads to widespread **tissue hypoperfusion**, especially to vital organs like the brain.
- Reduced cerebral blood flow results in impaired brain function, manifesting as **confusion, irritability**, and altered mental status.
*Decreased preload*
- Significant blood loss leads to a reduction in the **total circulating blood volume**.
- This reduction directly decreases the venous return to the heart, thus lowering the **end-diastolic volume** and subsequently, the **preload**.
*Increased thromboxane A2*
- In response to **vascular injury and bleeding**, the body initiates hemostasis, a critical component of which is platelet aggregation.
- **Thromboxane A2** is a potent vasoconstrictor and platelet aggregator released by activated platelets to form a **platelet plug** and help stop bleeding.
Acute Care US Medical PG Question 4: One hour after being admitted to the hospital for sharp, acute chest pain and diaphoresis, a 55-year-old woman with type 2 diabetes mellitus loses consciousness in the emergency department. There are no palpable pulses. Chest compressions are started. The patient has a history of breast cancer that was surgically treated 4 years ago. Prior to admission, the patient was on a long bus ride to visit her sister. Her medications include tamoxifen, atorvastatin, metoprolol, metformin, and insulin. Serum troponin levels are elevated. The cardiac rhythm is shown. Which of the following is the most appropriate next step in management?
- A. Defibrillation (Correct Answer)
- B. Coronary angiography
- C. Intravenous dextrose therapy
- D. Intravenous epinephrine therapy
- E. Intravenous glucagon therapy
Acute Care Explanation: ***Defibrillation***
- The ECG shows **ventricular fibrillation (VF)**, characterized by chaotic, disorganized electrical activity with no identifiable QRS complexes and no palpable pulse. VF is a **shockable rhythm**.
- According to ACLS guidelines, the immediate management for VF is **unsynchronized defibrillation** along with high-quality chest compressions.
- Defibrillation depolarizes the myocardium simultaneously, allowing the sinoatrial node to potentially resume normal electrical activity and restore organized cardiac rhythm.
- For refractory VF after initial shocks, epinephrine and antiarrhythmics (amiodarone or lidocaine) are added.
*Intravenous epinephrine therapy*
- Epinephrine is a vasopressor used in cardiac arrest to increase coronary and cerebral perfusion pressure.
- While epinephrine is given during VF arrest, it is administered **after** the initial defibrillation attempts, not as the immediate first step.
- Epinephrine is the primary drug for **non-shockable rhythms** (PEA and asystole), but defibrillation takes priority in shockable rhythms like VF.
*Intravenous glucagon therapy*
- Glucagon is used for severe **hypoglycemia** or **beta-blocker/calcium channel blocker overdose**.
- While the patient takes metoprolol (a beta-blocker), the clinical presentation with elevated troponin, chest pain, and VF rhythm clearly indicates an acute cardiac event, not beta-blocker toxicity.
- Glucagon has no role in the immediate management of cardiac arrest from VF.
*Coronary angiography*
- Coronary angiography is indicated for **post-cardiac arrest care** after return of spontaneous circulation (ROSC), especially in patients with suspected acute coronary syndrome.
- The patient has elevated troponin suggesting acute MI, making early angiography important **after** successful resuscitation.
- However, angiography cannot be performed during active cardiac arrest; immediate defibrillation and CPR are required first.
*Intravenous dextrose therapy*
- Dextrose is used to treat **hypoglycemia**.
- While the patient has diabetes and takes insulin (hypoglycemia risk), the presentation with chest pain, elevated troponin, and VF rhythm indicates acute coronary syndrome with cardiac arrest.
- Hypoglycemia does not cause VF; the rhythm is consistent with ischemic cardiac arrest requiring immediate defibrillation.
Acute Care US Medical PG Question 5: A 66-year-old man presents to the emergency department with a 3-hour history of crushing chest pain radiating to the left shoulder and neck. Patient states that the pain began suddenly when he was taking a walk around the block and has not improved with rest. He also mentions difficulty breathing and prefers to sit leaning forward. He denies ever having similar symptoms before. Past medical history is significant for hypertension, diagnosed 10 years ago, and hyperlipidemia diagnosed 8 years ago. Current medications are atorvastatin. Patient is also prescribed hydrochlorothiazide as an antihypertensive but is not compliant because he says it makes him urinate too often.
Vitals show a blood pressure of 152/90 mm Hg, pulse of 106/min, respirations of 22/min and oxygen saturation of 97% on room air. On physical exam, patient is profusely diaphoretic and hunched over in distress. Cardiac exam is unremarkable and lungs are clear to auscultation. During your examination, the patient suddenly becomes unresponsive and a pulse cannot be palpated. A stat ECG shows the following (see image). Which of the following is the next best step in management?
- A. Synchronized cardioversion
- B. Administer amiodarone
- C. Urgent echocardiography
- D. Administer epinephrine
- E. Unsynchronized cardioversion (Correct Answer)
Acute Care Explanation: ***Unsynchronized cardioversion***
- The ECG shows **ventricular fibrillation (VF)**, a chaotic electrical activity with no coordinated contractions, which leads to immediate cardiac arrest.
- In a patient who is unresponsive and pulseless with VF, **immediate unsynchronized defibrillation** (cardioversion) is the definitive treatment to restore a perfusing rhythm.
*Synchronized cardioversion*
- **Synchronized cardioversion** delivers an electrical shock timed to the QRS complex, used for unstable patients with a pulse and organized tachyarrhythmias (e.g., ventricular tachycardia with a pulse, atrial flutter, or atrial fibrillation).
- This patient is **pulseless** and in **ventricular fibrillation**, making synchronized cardioversion inappropriate and ineffective.
*Administer amiodarone*
- **Amiodarone** is an antiarrhythmic drug used in cardiac arrest protocols for **refractory VF/pulseless VT** after initial defibrillation attempts and epinephrine have failed.
- It is not the *initial* best step in a pulseless patient with VF, as electrical defibrillation is paramount.
*Urgent echocardiography*
- While an echocardiogram might be useful in identifying the underlying cause (e.g., myocardial infarction leading to VF), it is **not the immediate life-saving intervention** for a patient in cardiac arrest from VF.
- Delaying defibrillation for an echocardiogram would significantly worsen the patient's prognosis.
*Administer epinephrine*
- **Epinephrine** is a vasoconstrictor and cardiac stimulant used during **cardiac arrest**, typically given after the initial defibrillation attempt for VF/pulseless VT.
- It helps improve myocardial and cerebral blood flow but is **secondary to immediate defibrillation** in VF.
More Acute Care US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
