Tüm alıştırma soruları

A research institute maintains an ongoing registry of 30,000 patients who initiated therapy with a novel immunomodulatory agent for severe rheumatoid arthritis. Patients undergo protocolized clinical evaluations and provide serum samples every 6 months. Over a 10-year period, 42 patients in the registry develop a rare, atypical demyelinating syndrome. To evaluate whether pre-existing antibodies against a specific ubiquitous virus are associated with this adverse event, researchers select the 42 affected individuals. For each affected patient, they randomly identify four patients from the registry who had not developed the syndrome at the exact time the affected patient's diagnosis was made. The researchers then thaw and analyze the archived serum samples collected just prior to that time point for all 210 subjects to assess their viral antibody titers.

Which of the following best characterizes this research methodology and its primary epidemiological advantage?

A 24-year-old male presents to the emergency department supporting his right arm after an awkward fall during a recreational rugby match. He is in significant pain, and his right shoulder has a visibly 'squared-off' appearance. He complains of numbness over the lateral aspect of his shoulder. Arrange the following steps in the most appropriate chronological sequence for the acute management of this patient's presentation.

A 68-year-old man with a history of poorly controlled hypertension is brought to the emergency department due to sudden-onset, severe, tearing interscapular back pain. On arrival, his blood pressure is 215/115 mmHg, and his heart rate is 118/min. He appears diaphoretic and in severe distress. An electrocardiogram shows sinus tachycardia with no ischemic changes. A portable chest radiograph demonstrates a widened mediastinum. The physician strongly suspects an acute aortic dissection. Arrange the following evaluation and management steps in the most appropriate chronological sequence for this patient.

A 29-year-old male with a history of sickle cell trait presents to the emergency department with a painful, rigid erection that has persisted for 8 hours. He denies any trauma or use of erectile dysfunction medications. On physical examination, the corpora cavernosa are tense and tender, while the glans penis and corpus spongiosum remain flaccid. A dorsal penile nerve block is performed for local anesthesia. Cavernosal blood gas analysis reveals a $\text{pO}_2$ of $18\text{ mmHg}$, $\text{pCO}_2$ of $88\text{ mmHg}$, and $\text{pH}$ of $7.05$. Assuming the patient's condition remains refractory to each successive intervention, arrange the following management steps in the correct standard-of-care escalation sequence.

Clinical investigators are assessing the efficacy of a novel direct oral anticoagulant for the prevention of deep vein thrombosis (DVT) following total knee arthroplasty in a double-blind, placebo-controlled trial. The published results indicate that the new medication provides a Relative Risk Reduction (RRR) of $40\%$ compared to the placebo group. The authors also report that the Number Needed to Treat (NNT) to prevent one DVT event is $20$.

Based on these findings, which of the following best represents the incidence of DVT in the placebo group?

An ambulatory 29-year-old male construction worker presents to his primary care provider with a 6-month history of progressive fatigue, diminished libido, and a 6-kg (13-lb) weight gain. He states that he feels constantly sluggish and cold, even during warm weather. Fourteen months ago, he sustained a severe traumatic brain injury during a scaffolding collapse at work, which required a 3-week stay in the intensive care unit. His blood pressure is 105/70 mm Hg, and his pulse is 55/min. Physical examination reveals pale skin, sparse axillary and pubic hair, and a delayed relaxation phase of the deep tendon reflexes.

Laboratory studies show:

Which of the following is the most appropriate next step in the diagnostic evaluation of this patient?

A 51-year-old man is currently hospitalized for the management of acute complicated diverticulitis. Four days ago, he presented with severe left lower quadrant abdominal pain, and a computed tomography scan revealed a $4.2\text{-cm}$ pericolic abscess. The abscess was successfully managed with computed tomography-guided percutaneous drainage. Due to a documented history of extended-spectrum beta-lactamase (ESBL) urinary tract infections, he was empirically started on intravenous meropenem upon admission.

Today, the patient reports feeling well and his abdominal pain has completely resolved. He is tolerating a regular diet without nausea. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $122/78\text{ mmHg}$, and pulse is $76/\text{min}$. His leukocyte count has decreased from $17,500/\text{mm}^3$ at admission to $7,200/\text{mm}^3$. The percutaneous drain output has been negligible for the past 24 hours, and the catheter was removed this morning.

The finalized abscess fluid culture demonstrates heavy growth of *Escherichia coli* and *Bacteroides fragilis*. Susceptibility testing of the *E. coli* isolate reveals sensitivity to amoxicillin-clavulanate, ceftriaxone, and ciprofloxacin, with no evidence of ESBL production.

Which of the following is the most appropriate next step in the pharmacological management of this patient?

During morning rounds on the surgical step-down unit, a $57$-year-old male patient is evaluated for worsening shortness of breath and severe anterior chest pain. He is currently on postoperative day $7$ following an open mitral valve replacement and single-vessel coronary artery bypass graft. His medical history includes type 2 diabetes mellitus, medically managed obesity, and a $35$-pack-year smoking habit. The pain is described as deep and sharp, exacerbating significantly when he coughs.

Vital signs show a temperature of $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), pulse of $118/\text{min}$, respirations of $24/\text{min}$, and blood pressure of $92/64 \text{ mm Hg}$. Physical examination reveals a diaphoretic, ill-appearing man. Inspection of the midline sternotomy incision demonstrates marked surrounding erythema and a $2\text{-cm}$ separation of the proximal wound edges. A moderate amount of cloudy, malodorous exudate is draining from the defect. Upon palpation of the chest wall during respiration, the two halves of the sternum shift independently of one another. Laboratory studies are significant for a leukocyte count of $19,500/\text{mm}^3$.

Which of the following is the most appropriate next step in the management of this patient's condition?

A $49$-year-old man arrives at the emergency department due to a $24$-hour history of unremitting, severe abdominal pain. He reports multiple episodes of dark green vomiting and an inability to pass flatus since the onset of his symptoms. His surgical history is notable for a ruptured appendix requiring an open midline laparotomy at age $20$. His temperature is $38.5^\circ\text{C}$ ($101.3^\circ\text{F}$), blood pressure is $96/55\text{ mm Hg}$, pulse is $124/\text{min}$, and respirations are $22/\text{min}$. Physical examination reveals a visibly distended abdomen that is diffusely tender. There is pronounced involuntary guarding and board-like rigidity. Laboratory studies show a leukocyte count of $18,500/\text{mm}^3$ with $15\%$ bandemia and a serum lactate of $4.2\text{ mmol/L}$. An upright abdominal radiograph demonstrates multiple dilated loops of small bowel with air-fluid levels, and no free air under the diaphragm. Which of the following is the most appropriate next step in the management of this patient?

A research team has just finished collecting data for a multicenter retrospective cohort study investigating the association between the use of a novel sodium-glucose cotransporter-2 (SGLT2) inhibitor and the incidence of recurrent nephrolithiasis in patients with type 2 diabetes. The investigators note that concurrent use of thiazide diuretics is a significant confounder, as thiazides are commonly prescribed to this population and independently reduce the risk of calcium-based kidney stones. Because data collection is already complete, which of the following statistical or analytical methods are appropriate to control for the confounding effect of thiazide diuretic use at this current stage? (Select all that apply)

Match the following high-resolution esophageal manometry (HRM) profiles based on the Chicago Classification to their most appropriate clinical diagnoses.

A $24$-year-old woman presents to the emergency department with a $2$-day history of severe abdominal cramps and frequent, grossly bloody diarrhea. She recalls eating an undercooked hamburger at a picnic $4$ days prior. Her temperature is $37.2^\circ\mathrm{C}$ ($99.0^\circ\mathrm{F}$), blood pressure is $110/70\text{ mmHg}$, and pulse is $105\text{/min}$. Physical examination reveals diffuse abdominal tenderness without rebound or guarding. Suspecting an infection with enterohemorrhagic \textit{Escherichia coli} (EHEC), arrange the following clinical management steps in the most appropriate chronological order.

A $71$-year-old male is transported to the emergency room by emergency medical services after his family found him writhing in severe abdominal pain. He reports a $3$-day history of colicky abdominal pain, intractable nausea, and bilious vomiting. He has not passed stool or flatus for the past $48$ hours. His medical history includes hypertension, hyperlipidemia, and an open partial colectomy performed $8$ years ago. On arrival, his temperature is $39.4^\circ\text{C}$ ($102.9^\circ\text{F}$), blood pressure is $88/50\text{ mmHg}$, pulse is $128/\text{min}$, and respiratory rate is $26/\text{min}$. Physical examination reveals a tensely distended abdomen. There is diffuse, severe tenderness to palpation with involuntary guarding and positive rebound tenderness. Auscultation reveals a complete absence of bowel sounds.

Laboratory studies show:

An upright abdominal radiograph displays multiple dilated loops of small bowel with prominent air-fluid levels and a complete absence of gas in the colon and rectum.

Which of the following is the most appropriate next step in management?

An inpatient oncology service evaluates a 29-year-old man who developed a sudden fever. He is currently on day 12 of induction chemotherapy for acute myeloid leukemia. He reports feeling profoundly fatigued but denies cough, shortness of breath, dysuria, abdominal pain, or diarrhea. Vital signs show a temperature of 38.9°C (102.0°F), blood pressure of 118/74 mm Hg, pulse of 98/min, and respirations of 16/min. Physical examination reveals clear lung fields bilaterally, no cardiac murmurs, and a non-tender abdomen. The insertion site of his right internal jugular central venous catheter is clean, dry, and intact with no surrounding erythema, induration, or purulent discharge. Laboratory studies are significant for a leukocyte count of $300/\text{mm}^3$ with $10\%$ neutrophils (Absolute Neutrophil Count = $30/\text{mm}^3$). Which of the following is the most appropriate next step in the management of this patient?

Researchers are conducting a randomized controlled trial to evaluate the efficacy of a newly developed inhaled corticosteroid compared to standard treatment for severe asthma. The initial, unadjusted analysis demonstrates a relative risk for asthma exacerbations of $0.8$ ($p = 0.04$) in the new medication group compared to the standard treatment group. To further understand the drug's clinical profile, the researchers stratify the trial participants by their baseline blood eosinophil levels. In the stratum of patients with high eosinophil counts, the relative risk is $0.4$ ($p < 0.01$). In the stratum of patients with normal eosinophil counts, the relative risk is $1.0$ ($p = 0.85$). Which of the following epidemiological concepts best explains these stratified findings?

A 62-year-old man is brought to the emergency department via ambulance with a sudden onset of severe, tearing chest pain that radiates to his interscapular region. His medical history is significant for poorly controlled hypertension. On presentation, he is diaphoretic and in severe distress. Blood pressure is 215/115 mm Hg in the right arm and 180/95 mm Hg in the left arm. Heart rate is 112/min. A new early diastolic decrescendo murmur is heard at the right upper sternal border. Electrocardiogram shows sinus tachycardia and left ventricular hypertrophy without acute ischemic changes. Chest x-ray reveals a widened mediastinum. A diagnosis of acute aortic dissection is suspected. Arrange the following steps in the most appropriate sequential order for the management of this patient.

A 45-year-old man is hospitalized due to severe acute pancreatitis secondary to alcohol use. He is admitted to the intensive care unit and managed with aggressive intravenous fluid resuscitation, analgesia, and enteral nutrition. On day 3 of hospitalization, the patient develops a temperature of $38.8^{\circ}\text{C}$ ($101.8^{\circ}\text{F}$). His blood pressure is $112/70\text{ mmHg}$, pulse is $114\text{/min}$, and respirations are $22\text{/min}$. Physical examination shows a distended abdomen with severe epigastric tenderness but no rebound or guarding.

Laboratory studies show a leukocyte count of $18,500/\text{mm}^3$ and a serum lipase of $1,200\text{ U/L}$. A contrast-enhanced CT scan of the abdomen reveals acute inflammation of the pancreas with a $6\text{-cm}$ area of non-enhancement in the pancreatic body and tail, consistent with $>30\%$ pancreatic necrosis. There is no gas observed within the necrotic collection. The gallbladder is surgically absent, and the biliary tree is not dilated. Blood, urine, and sputum cultures are obtained.

What is the most appropriate next step in management?

A 52-year-old woman presents to the emergency department with a 2-day history of left lower quadrant abdominal pain. The pain is constant and described as a dull ache. She reports mild nausea but no vomiting, diarrhea, or hematochezia. Her medical history is unremarkable, and she takes no daily medications. Temperature is 37.3°C (99.1°F), blood pressure is 128/82 mmHg, pulse is 84/min, and respirations are 14/min. Abdominal examination reveals focal tenderness in the left lower quadrant without guarding, rigidity, or rebound tenderness. Bowel sounds are normal. Laboratory testing shows a leukocyte count of 9,500/mm³ with a normal differential. A CT scan of the abdomen and pelvis with intravenous contrast demonstrates wall thickening and peri-colic fat stranding in the sigmoid colon. There is no evidence of an abscess, stricture, fistula, or free intraperitoneal air. The patient is able to tolerate oral fluids without difficulty. Which of the following is the most appropriate next step in management?

Medical staff are reassessing a $65$-year-old female patient in the critical care ward due to increasing somnolence and tachypnea. The patient was hospitalized $72$ hours prior for septic shock complicating severe community-acquired pneumonia. Initial management included aggressive intravenous fluid resuscitation and empiric antimicrobial therapy with intravenous vancomycin and piperacillin-tazobactam. She has a past medical history of chronic obstructive pulmonary disease and left ventricular hypertrophy. Yesterday, her hemodynamics improved, allowing the discontinuation of vasopressor support. Today, the blood cultures obtained on admission demonstrate heavy growth of Streptococcus pneumoniae, which is reported as susceptible to ceftriaxone and penicillin.

Currently, the patient appears lethargic and is using accessory muscles of respiration. Current vital signs include a temperature of $37.8^\circ C$ ($100.0^\circ F$), blood pressure of $115/75\ mmHg$, heart rate of $105/min$, and a respiratory rate of $30/min$. Pulse oximetry indicates an oxygen saturation of $90\%$ while receiving supplemental oxygen via a high-flow nasal cannula. Physical examination reveals diminished breath sounds bilaterally without jugular venous distention. A bedside point-of-care ultrasound demonstrates a collapsible inferior vena cava and a predominant A-line pattern bilaterally without significant B-lines.

Laboratory evaluation is notable for:
Sodium: $138\ mEq/L$
Chloride: $104\ mEq/L$
Bicarbonate: $15\ mEq/L$
Blood urea nitrogen: $32\ mg/dL$
Creatinine: $1.8\ mg/dL$

An arterial blood gas analysis reveals:
$pH$: $7.22$
$PaCO_2$: $38\ mmHg$
$PaO_2$: $62\ mmHg$
$HCO_3^-$: $15\ mEq/L$

Which of the following are appropriate next steps in the management of this patient? (Select all that apply)

A $52$-year-old man visits his primary care physician to discuss screening for pancreatic cancer after a close friend was recently diagnosed with the disease. The patient has no family history of malignancy, is entirely asymptomatic, and has a normal physical examination. The prevalence of pancreatic cancer in his demographic is exceedingly low. The physician explains that a novel serum biomarker, Cancer Antigen X (CA-X), has recently been developed for clinical use. At the standard diagnostic cutoff of $35\text{ U/mL}$, the test has a sensitivity of $98\%$ and a specificity of $90\%$. The physician warns that if this test is applied to the general asymptomatic population, the vast majority of positive results would be false positives due to the low disease prevalence. To improve the test's utility for mass screening in low-risk populations, the manufacturer proposes a revised protocol that shifts the diagnostic cutoff to $70\text{ U/mL}$.

Which of the following best describes the expected impact on the test's performance characteristics when adopting the $70\text{ U/mL}$ cutoff instead of the $35\text{ U/mL}$ cutoff?