A 44-year-old man is brought to the emergency department after sustaining high-voltage electrical burns over his left upper limb. On examination, the tip of his left middle finger is charred, and there are 2nd-degree burns involving the whole of the left upper limb. Radial and ulnar pulses are strong, and there are no signs of compartment syndrome. An exit wound is present over the sole of his right foot. His temperature is 37.7°C (99.8°F), the blood pressure is 110/70 mm Hg, the pulse is 105/min, and the respiratory rate is 26/min. His urine is reddish-brown, and urine output is 0.3 mL/kg/h. Laboratory studies show:
Hemoglobin 13.9 g/dL
Hematocrit 33%
Leukocyte count 11,111/mm3
Serum
Creatinine 4.6 mg/dL
Creatine phosphokinase 15,230 U/L
K+ 7.7 mEq/L
Na+ 143 mEq/L
What is the most likely mechanism for this patient's renal failure?
Q2
A 57-year-old man is admitted to the burn unit after he was brought to the emergency room following an accidental fire in his house. His past medical history is unknown due to his current clinical condition. Currently, his blood pressure is 75/40 mmHg, pulse rate is 140/min, and respiratory rate is 17/min. The patient is subsequently intubated and started on aggressive fluid resuscitation. A Swan-Ganz catheter is inserted to clarify his volume status. Which of the following hemodynamic parameters would you expect to see in this patient?
Q3
An 83-year-old male presents with dyspnea, orthopnea, and a chest radiograph demonstrating pulmonary edema. A diagnosis of congestive heart failure is considered. The following clinical measurements are obtained: 100 bpm heart rate, 0.2 mL O2/mL systemic blood arterial oxygen content, 0.1 mL O2/mL pulmonary arterial oxygen content, and 400 mL O2/min oxygen consumption. Using the above information, which of the following values represents this patient's cardiac stroke volume?
Q4
A 38-year-old man is brought to the emergency department 35 minutes after he sustained a gunshot wound to the right thigh. He has type 1 diabetes mellitus. On arrival, his pulse is 112/min, respirations are 20/min, and blood pressure is 115/69 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 98%. There is an entrance wound on the anteromedial surface of the right thigh 2 cm below the inguinal ligament. There is no bruit or thrill. There is no exit wound. The pedal pulse is diminished on the right side compared to the left. The abdomen is soft and nontender. The remainder of the examination shows no abnormalities. Laboratory studies show:
Hematocrit 46%
Serum
Urea nitrogen 24 mg/dL
Glucose 160 mg/dL
Creatinine 3.1 mg/dL
Which of the following is the most appropriate next step in management?
Q5
A 23-year-old patient presents to the emergency department after a motor vehicle accident. The patient was an unrestrained driver involved in a head-on collision. The patient is heavily intoxicated on what he claims is only alcohol. An initial trauma assessment is performed, and is notable for significant bruising of the right forearm. The patient is in the trauma bay, and complains of severe pain in his right forearm. A physical exam is performed and is notable for pallor, decreased sensation, and cool temperature of the skin of the right forearm. Pain is elicited upon passive movement of the right forearm and digits. A thready radial pulse is palpable. A FAST exam is performed, and is negative for signs of internal bleeding. The patient's temperature is 99.5°F (37.5°C), pulse is 100/min, blood pressure is 110/70 mmHg, respirations are 12/min, and oxygen saturation is 98% on room air. Radiography of the right forearm is ordered. The patient is still heavily intoxicated. Which of the following is the best next step in management?
Q6
A 35-year-old woman volunteers for a study on respiratory physiology. Pressure probes A and B are placed as follows:
Probe A: between the parietal and visceral pleura
Probe B: within the cavity of an alveolus
The probes provide a pressure reading relative to atmospheric pressure. To obtain a baseline reading, she is asked to sit comfortably and breathe normally. Which of the following sets of values will most likely be seen at the end of inspiration?
Q7
A 35-year-old man is referred to a physical therapist due to limitation of movement in the wrist and fingers of his left hand. He cannot hold objects or perform daily activities with his left hand. He broke his left arm at the humerus one month ago. The break was simple and treatment involved a cast for one month. Then he lost his health insurance and could not return for follow up. Only after removing the cast did he notice the movement issues in his left hand and wrist. His past medical history is otherwise insignificant, and vital signs are within normal limits. On examination, the patient’s left hand is pale and flexed in a claw-like position. It is firm and tender to palpation. Right radial pulse is 2+ and left radial pulse is 1+. The patient is unable to actively extend his fingers and wrist, and passive extension is difficult and painful. Which of the following is a proper treatment for the presented patient?
Q8
A 58-year-old man presents to the emergency department with severe right leg pain accompanied by tingling and weakness. His condition started suddenly 3 hours ago when he was watching a movie. His medical history is remarkable for type 2 diabetes mellitus and hypertension. He has been smoking 20–30 cigarettes per day for the past 35 years. His vital signs include a blood pressure of 149/85 mm Hg, a temperature of 36.9°C (98.4°F), and an irregular pulse of 96/min. On physical examination, his right popliteal and posterior tibial pulses are absent. His right leg is pale and cold. Which of the following is the most likely diagnosis?
Q9
A 31-year-old man presents to the Emergency Department with severe left leg pain and paresthesias 4 hours after his leg got trapped by the closing door of a bus. Initially, he had a mild pain which gradually increased to unbearable levels. Past medical history is noncontributory. In the Emergency Department, his blood pressure is 130/80 mm Hg, heart rate is 87/min, respiratory rate is 14/min, and temperature is 36.8℃ (98.2℉). On physical exam, his left calf is firm and severely tender on palpation. The patient cannot actively dorsiflex his left foot, and passive dorsiflexion is limited. Posterior tibial and dorsalis pedis pulses are 2+ in the right leg and 1+ in the left leg. Axial load does not increase the pain. Which of the following is the best next step in the management of this patient?
Q10
Two hours after undergoing a left femoral artery embolectomy, an obese 63-year-old woman has severe pain, numbness, and tingling of the left leg. The surgery was without complication and peripheral pulses were weakly palpable postprocedure. She has type 2 diabetes mellitus, peripheral artery disease, hypertension, and hypercholesterolemia. Prior to admission, her medications included insulin, enalapril, carvedilol, aspirin, and rosuvastatin. She appears uncomfortable. Her temperature is 37.1°C (99.3°F), pulse is 98/min, and blood pressure is 132/90 mm Hg. Examination shows a left groin surgical incision. The left lower extremity is swollen, stiff, and tender on palpation. Dorsiflexion of her left foot causes severe pain in her calf. Femoral pulses are palpated bilaterally. Pedal pulses are weaker on the left side as compared to the right side. Laboratory studies show:
Hemoglobin 12.1
Leukocyte count 11,300/mm3
Platelet count 189,000/mm3
Serum
Glucose 222 mg/dL
Creatinine 1.1 mg/dL
Urinalysis is within normal limits. Which of the following is the most likely cause of these findings?
Compartment syndrome diagnosis and fasciotomy US Medical PG Practice Questions and MCQs
Question 1: A 44-year-old man is brought to the emergency department after sustaining high-voltage electrical burns over his left upper limb. On examination, the tip of his left middle finger is charred, and there are 2nd-degree burns involving the whole of the left upper limb. Radial and ulnar pulses are strong, and there are no signs of compartment syndrome. An exit wound is present over the sole of his right foot. His temperature is 37.7°C (99.8°F), the blood pressure is 110/70 mm Hg, the pulse is 105/min, and the respiratory rate is 26/min. His urine is reddish-brown, and urine output is 0.3 mL/kg/h. Laboratory studies show:
Hemoglobin 13.9 g/dL
Hematocrit 33%
Leukocyte count 11,111/mm3
Serum
Creatinine 4.6 mg/dL
Creatine phosphokinase 15,230 U/L
K+ 7.7 mEq/L
Na+ 143 mEq/L
What is the most likely mechanism for this patient's renal failure?
A. Septicemia leading to acute pyelonephritis
B. Rhabdomyolysis, myoglobinuria, and renal injury (Correct Answer)
C. Direct visceral electrical injury to the kidneys
D. Fluid and electrolyte loss and hypovolemia
E. Volume overload because of excessive intravenous fluid resuscitation
Explanation: ***Rhabdomyolysis, myoglobinuria, and renal injury***
- The high **creatine phosphokinase (CPK)** level of 15,230 U/L indicates significant **muscle damage** (**rhabdomyolysis**) from the high-voltage electrical burn.
- **Myoglobin** released from damaged muscle is **nephrotoxic** and precipitates in the renal tubules, leading to **acute kidney injury**, evidenced by **reddish-brown urine** and elevated **creatinine (4.6 mg/dL)**.
*Septicemia leading to acute pyelonephritis*
- While burns can lead to infection, there are no specific signs of **septicemia** or **pyelonephritis** (e.g., fever, flank pain) in the provided information.
- The patient's **hyperkalemia** and elevated **CPK** are not typical findings for pyelonephritis.
*Direct visceral electrical injury to the kidneys*
- **Direct electrical injury** to internal organs such as the kidneys is **rare** unless the electrical current traverses the abdomen.
- The entry and exit wounds (left upper limb and right foot) suggest a current path that is **less likely** to directly involve the kidneys.
*Fluid and electrolyte loss and hypovolemia*
- Although **burn injuries** can cause significant fluid loss, this patient's **blood pressure (110/70 mm Hg)** and **heart rate (105/min)** do not strongly suggest severe **hypovolemic shock**.
- The **hemoglobin (19.9 g/dL)** and **hematocrit (33%)** also do not directly point to severe acute fluid loss as the primary cause of renal failure in the context of other findings.
*Volume overload because of excessive intravenous fluid resuscitation*
- The patient's **low urine output (0.3 mL/kg/h)** suggests **renal failure**, not fluid overload.
- There is no mention of **fluid resuscitation** being administered, making this an unlikely cause of the current presentation.
Question 2: A 57-year-old man is admitted to the burn unit after he was brought to the emergency room following an accidental fire in his house. His past medical history is unknown due to his current clinical condition. Currently, his blood pressure is 75/40 mmHg, pulse rate is 140/min, and respiratory rate is 17/min. The patient is subsequently intubated and started on aggressive fluid resuscitation. A Swan-Ganz catheter is inserted to clarify his volume status. Which of the following hemodynamic parameters would you expect to see in this patient?
Explanation: ***Cardiac output: ↓, systemic vascular resistance: ↑, pulmonary artery wedge pressure: ↓***
- The patient's **hypotension (75/40 mmHg)** and **tachycardia (140/min)**, combined with severe burns, indicate **hypovolemic shock** due to massive fluid loss from damaged capillaries.
- In response to decreased cardiac output and hypovolemia, the body compensates by increasing **systemic vascular resistance (SVR)** to maintain perfusion to vital organs, and **pulmonary artery wedge pressure (PAWP)** will be low due to reduced intravascular volume.
*Cardiac output: ↓, systemic vascular resistance: ↔, pulmonary artery wedge pressure: ↔*
- This option incorrectly suggests that systemic vascular resistance and pulmonary artery wedge pressure would be normal, which is inconsistent with **hypovolemic shock**.
- In shock, the body's compensatory mechanisms would lead to significant changes in SVR and PAWP, not maintain them at baseline.
*Cardiac output: ↑, systemic vascular resistance: ↑, pulmonary artery wedge pressure: ↔*
- Increased cardiac output is usually seen in **distributive shock** (e.g., septic shock) where vasodilation leads to reduced SVR, not increased SVR as suggested here.
- An elevated SVR coupled with an increased cardiac output would typically result in a higher blood pressure unless there is a compensatory drop in other parameters.
*Cardiac output: ↑, systemic vascular resistance: ↓, pulmonary artery wedge pressure: ↔*
- This pattern (high cardiac output, low SVR) is characteristic of **distributive shock**, such as **septic shock** or anaphylactic shock, rather than the hypovolemic shock expected in a burn patient.
- Severe burns primarily cause massive fluid shifts, leading to hypovolemia and a reduced cardiac output, not an elevated one.
*Cardiac output: ↔, systemic vascular resistance: ↔, pulmonary artery wedge pressure: ↔*
- This scenario represents **normal hemodynamic parameters**, which would not be expected in a patient experiencing severe shock from extensive burns.
- The patient's clinical presentation (hypotension, tachycardia) clearly indicates a state of hemodynamic instability.
Question 3: An 83-year-old male presents with dyspnea, orthopnea, and a chest radiograph demonstrating pulmonary edema. A diagnosis of congestive heart failure is considered. The following clinical measurements are obtained: 100 bpm heart rate, 0.2 mL O2/mL systemic blood arterial oxygen content, 0.1 mL O2/mL pulmonary arterial oxygen content, and 400 mL O2/min oxygen consumption. Using the above information, which of the following values represents this patient's cardiac stroke volume?
A. 30 mL/beat
B. 70 mL/beat
C. 40 mL/beat (Correct Answer)
D. 60 mL/beat
E. 50 mL/beat
Explanation: ***40 mL/beat***
- First, calculate cardiac output (CO) using the **Fick principle**: CO = Oxygen Consumption / (Arterial O2 content - Venous O2 content). Here, CO = 400 mL O2/min / (0.2 mL O2/mL - 0.1 mL O2/mL) = 400 mL O2/min / 0.1 mL O2/mL = **4000 mL/min**.
- Next, calculate stroke volume (SV) using the formula: SV = CO / Heart Rate. Given a heart rate of 100 bpm, SV = 4000 mL/min / 100 beats/min = **40 mL/beat**.
*30 mL/beat*
- This answer would result if there was an error in calculating either the **cardiac output** or if the **arteriovenous oxygen difference** was overestimated.
- A stroke volume of 30 mL/beat with a heart rate of 100 bpm would yield a cardiac output of 3 L/min, which is sub-physiologic for an oxygen consumption of 400 mL/min given the provided oxygen content values.
*70 mL/beat*
- This stroke volume is higher than calculated and would imply either a significantly **lower heart rate** or a much **higher cardiac output** than derived from the Fick principle with the given values.
- A stroke volume of 70 mL/beat at a heart rate of 100 bpm would mean a cardiac output of 7 L/min, which is inconsistent with the provided oxygen consumption and arteriovenous oxygen difference.
*60 mL/beat*
- This value is higher than the correct calculation, suggesting an error in the initial calculation of **cardiac output** or the **avO2 difference**.
- To get 60 mL/beat, the cardiac output would need to be 6000 mL/min, which would mean an avO2 difference of 0.067 mL O2/mL, not 0.1 mL O2/mL.
*50 mL/beat*
- This stroke volume would result from an incorrect calculation of the **cardiac output**, potentially from a slight miscalculation of the **arteriovenous oxygen difference**.
- A stroke volume of 50 mL/beat at 100 bpm would mean a cardiac output of 5 L/min, requiring an avO2 difference of 0.08 mL O2/mL, which is not consistent with the given values.
Question 4: A 38-year-old man is brought to the emergency department 35 minutes after he sustained a gunshot wound to the right thigh. He has type 1 diabetes mellitus. On arrival, his pulse is 112/min, respirations are 20/min, and blood pressure is 115/69 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 98%. There is an entrance wound on the anteromedial surface of the right thigh 2 cm below the inguinal ligament. There is no bruit or thrill. There is no exit wound. The pedal pulse is diminished on the right side compared to the left. The abdomen is soft and nontender. The remainder of the examination shows no abnormalities. Laboratory studies show:
Hematocrit 46%
Serum
Urea nitrogen 24 mg/dL
Glucose 160 mg/dL
Creatinine 3.1 mg/dL
Which of the following is the most appropriate next step in management?
A. Digital subtraction angiography
B. Wound cleaning and tetanus toxoid
C. CT angiography
D. Duplex ultrasonography (Correct Answer)
E. Fasciotomy
Explanation: ***Duplex ultrasonography***
- The patient has suffered a **gunshot wound** to the thigh with a **diminished pedal pulse**, indicating potential **vascular injury** (a "soft sign" requiring imaging).
- Given his **significantly elevated creatinine (3.1 mg/dL)** and **type 1 diabetes mellitus**, imaging studies requiring **IV iodinated contrast** carry substantial risk for **contrast-induced nephropathy** and further renal deterioration.
- **Duplex ultrasonography** is a **non-invasive, contrast-free method** to assess vascular flow and identify injuries like **arterial dissection**, **thrombosis**, or **pseudoaneurysm**. While operator-dependent, it is the most appropriate initial diagnostic step in this hemodynamically stable patient with significant renal impairment.
- This allows vascular assessment while **minimizing nephrotoxic risk** in a patient with pre-existing renal dysfunction.
*CT angiography*
- **CT angiography** is the **gold standard** for evaluating penetrating extremity trauma with soft signs of vascular injury in most cases, offering rapid and highly accurate vascular imaging.
- However, it requires administration of **intravenous iodinated contrast**, which poses significant risk for **contrast-induced nephropathy** in this patient with **baseline creatinine of 3.1 mg/dL** and **diabetes mellitus**.
- While CTA would typically be preferred in trauma settings, the severe renal impairment makes duplex ultrasonography the safer initial choice in this stable patient.
*Digital subtraction angiography*
- This is an **invasive angiographic technique** that uses **iodinated contrast** and carries even higher contrast load than CTA, posing substantial risk for **contrast-induced nephropathy** given the patient's **elevated creatinine**.
- While it offers high resolution and therapeutic capability, the risks associated with contrast and invasive arterial access outweigh its benefits for initial assessment in this scenario.
- Reserved for cases where intervention is anticipated or non-invasive imaging is inconclusive.
*Wound cleaning and tetanus toxoid*
- These are essential components of wound care for any penetrating injury but do not address the immediate concern of **potential vascular injury** causing the diminished pedal pulse.
- Prioritizing definitive diagnosis of vascular compromise is critical before focusing solely on local wound management, as a missed arterial injury could lead to limb loss.
*Fasciotomy*
- **Fasciotomy** is a surgical procedure to relieve **compartment syndrome**, which can develop secondary to vascular injury, reperfusion, or significant soft tissue trauma.
- While compartment syndrome is a risk with this injury, there is no immediate clinical evidence of it (no severe pain out of proportion to exam, no tense compartments documented).
- Diagnosis of the vascular injury should be established first, as fasciotomy may be needed later if ischemia is prolonged or after revascularization.
Question 5: A 23-year-old patient presents to the emergency department after a motor vehicle accident. The patient was an unrestrained driver involved in a head-on collision. The patient is heavily intoxicated on what he claims is only alcohol. An initial trauma assessment is performed, and is notable for significant bruising of the right forearm. The patient is in the trauma bay, and complains of severe pain in his right forearm. A physical exam is performed and is notable for pallor, decreased sensation, and cool temperature of the skin of the right forearm. Pain is elicited upon passive movement of the right forearm and digits. A thready radial pulse is palpable. A FAST exam is performed, and is negative for signs of internal bleeding. The patient's temperature is 99.5°F (37.5°C), pulse is 100/min, blood pressure is 110/70 mmHg, respirations are 12/min, and oxygen saturation is 98% on room air. Radiography of the right forearm is ordered. The patient is still heavily intoxicated. Which of the following is the best next step in management?
A. Fasciotomy (Correct Answer)
B. IV fluids
C. Analgesics
D. Pressure measurement
E. Detoxification
Explanation: ***Fasciotomy***
- The patient exhibits classic signs of **acute compartment syndrome**, including severe pain out of proportion to injury, pain on passive stretch, pallor, decreased sensation, and cool extremity, despite a palpable pulse. These symptoms necessitate immediate surgical intervention to relieve pressure.
- A **fasciotomy** is the definitive treatment for acute compartment syndrome to prevent irreversible muscle and nerve damage, and potentially limb loss.
*IV fluids*
- While fluid resuscitation is important in trauma, the patient's current vital signs (BP 110/70 mmHg, pulse 100/min) do not indicate immediate shock requiring aggressive IV fluid administration over addressing the limb-threatening compartment syndrome.
- Prioritizing IV fluids without addressing **compartment syndrome** could lead to permanent loss of limb function.
*Analgesics*
- Administering analgesics might mask the escalating pain a key symptom of compartment syndrome, which could delay diagnosis and definitive treatment.
- While pain control is important, it should not supersede measures to prevent irreversible tissue damage.
*Pressure measurement*
- While compartment pressure measurement can confirm the diagnosis of compartment syndrome, the clinical presentation in this case is so compelling that delaying definitive treatment for pressure measurement is not the best next step.
- Clinical signs and symptoms are often sufficient for diagnosis, and surgical intervention should not be deferred pending pressure readings in clear-cut cases.
*Detoxification*
- Detoxification for alcohol intoxication is not an emergent and immediate priority in comparison to the limb-threatening condition of acute compartment syndrome.
- Addressing the **compartment syndrome** is critical for preserving limb viability, whereas detoxification can be managed once acute medical emergencies are controlled.
Question 6: A 35-year-old woman volunteers for a study on respiratory physiology. Pressure probes A and B are placed as follows:
Probe A: between the parietal and visceral pleura
Probe B: within the cavity of an alveolus
The probes provide a pressure reading relative to atmospheric pressure. To obtain a baseline reading, she is asked to sit comfortably and breathe normally. Which of the following sets of values will most likely be seen at the end of inspiration?
A. Probe A: -6 mm Hg; Probe B: 0 mm Hg (Correct Answer)
B. Probe A: 0 mm Hg; Probe B: -1 mm Hg
C. Probe A: -4 mm Hg; Probe B: 0 mm Hg
D. Probe A: -4 mm Hg; Probe B: -1 mm Hg
E. Probe A: -6 mm Hg; Probe B: -1 mm Hg
Explanation: ***Probe A: -6 mm Hg; Probe B: 0 mm Hg***
- At the **end of inspiration**, the **intrapleural pressure (Probe A)** is at its most negative, typically around -6 to -8 cm H2O (equivalent to -4 to -6 mmHg), reflecting the maximum expansion of the thoracic cavity.
- At the **end of inspiration**, just before exhalation begins, there is **no airflow**, so the **intrapulmonary pressure (Probe B)** equalizes with atmospheric pressure, resulting in a 0 mm Hg reading.
*Probe A: 0 mm Hg; Probe B: -1 mm Hg*
- An **intrapleural pressure of 0 mm Hg** would indicate a **pneumothorax** since it should always be negative to prevent lung collapse.
- An **intrapulmonary pressure of -1 mm Hg** would indicate that **inspiration is still ongoing**, as air would be flowing into the lungs.
*Probe A: -4 mm Hg; Probe B: 0 mm Hg*
- While an **intrapulmonary pressure of 0 mm Hg** is correct at the end of inspiration, an **intrapleural pressure of -4 mm Hg** is typical for the **end of expiration (Functional Residual Capacity)** during quiet breathing, not the end of inspiration.
- The **intrapleural pressure becomes more negative** during inspiration due to increased thoracic volume, so -4 mm Hg would be insufficient.
*Probe A: -4 mm Hg; Probe B: -1 mm Hg*
- An **intrapleural pressure of -4 mm Hg** is the normal pressure at the **end of expiration**, not the end of inspiration, where it becomes more negative.
- An **intrapulmonary pressure of -1 mm Hg** indicates that **inspiration is still in progress**, not at its end, as air would still be flowing into the lungs.
*Probe A: -6 mm Hg; Probe B: -1 mm Hg*
- While an **intrapleural pressure of -6 mm Hg** is consistent with the end of inspiration, an **intrapulmonary pressure of -1 mm Hg** means that **airflow is still occurring into the lungs**.
- At the **very end of inspiration**, just before the start of exhalation, airflow momentarily ceases, and intrapulmonary pressure becomes zero relative to the atmosphere.
Question 7: A 35-year-old man is referred to a physical therapist due to limitation of movement in the wrist and fingers of his left hand. He cannot hold objects or perform daily activities with his left hand. He broke his left arm at the humerus one month ago. The break was simple and treatment involved a cast for one month. Then he lost his health insurance and could not return for follow up. Only after removing the cast did he notice the movement issues in his left hand and wrist. His past medical history is otherwise insignificant, and vital signs are within normal limits. On examination, the patient’s left hand is pale and flexed in a claw-like position. It is firm and tender to palpation. Right radial pulse is 2+ and left radial pulse is 1+. The patient is unable to actively extend his fingers and wrist, and passive extension is difficult and painful. Which of the following is a proper treatment for the presented patient?
A. Surgical release (Correct Answer)
B. Botulinum toxin injections
C. Collagenase injections
D. Needle fasciotomy
E. Corticosteroid injections
Explanation: ***Surgical release***
- The patient presents with classic signs of **established Volkmann's ischemic contracture** (claw-like hand, firm fibrotic tissue, limited movement, decreased radial pulse), which is the end-stage result of untreated compartment syndrome that occurred during fracture healing.
- Since this is **chronic contracture (one month post-injury)**, the appropriate surgical treatment involves **reconstructive procedures** such as muscle slide operations, tendon lengthening, tendon transfers, neurolysis, or in severe cases, free functional muscle transfer to restore hand function.
- Emergency fasciotomy would have been appropriate for **acute compartment syndrome** (within 6-8 hours of onset), but at this stage, the treatment focuses on releasing fibrotic tissue and restoring function through reconstructive surgery.
*Botulinum toxin injections*
- **Botulinum toxin** is used to relax spastic muscles in neurological conditions (e.g., cerebral palsy, stroke), but it does not address the underlying **ischemic fibrosis and muscle necrosis** of Volkmann's contracture.
- It would not improve the structural contracture or restore blood flow in this patient.
*Collagenase injections*
- **Collagenase injections** are used for localized fascial contractures like Dupuytren's contracture, where enzymatic breakdown of collagen cords can restore finger extension.
- They are ineffective for **Volkmann's contracture**, which involves widespread ischemic muscle necrosis, fibrosis, and nerve damage requiring surgical reconstruction.
*Needle fasciotomy*
- **Needle fasciotomy** is a minimally invasive technique for Dupuytren's contracture, involving percutaneous disruption of fascial cords.
- It is not suitable for **Volkmann's contracture**, which requires extensive surgical release of fibrotic muscle compartments, possible tendon transfers, and neurolysis—procedures that cannot be accomplished with needle techniques.
*Corticosteroid injections*
- **Corticosteroids** reduce inflammation in conditions like tenosynovitis or trigger finger.
- They would not address the **ischemic muscle necrosis and fibrotic contracture** in Volkmann's contracture and could potentially delay appropriate surgical treatment.
Question 8: A 58-year-old man presents to the emergency department with severe right leg pain accompanied by tingling and weakness. His condition started suddenly 3 hours ago when he was watching a movie. His medical history is remarkable for type 2 diabetes mellitus and hypertension. He has been smoking 20–30 cigarettes per day for the past 35 years. His vital signs include a blood pressure of 149/85 mm Hg, a temperature of 36.9°C (98.4°F), and an irregular pulse of 96/min. On physical examination, his right popliteal and posterior tibial pulses are absent. His right leg is pale and cold. Which of the following is the most likely diagnosis?
A. Buerger's disease
B. Leriche syndrome
C. Acute limb ischemia (Correct Answer)
D. CREST syndrome
E. Deep vein thrombosis
Explanation: ***Acute limb ischemia***
- The sudden onset of **severe leg pain**, **tingling**, **weakness**, and the **six P's** (pain, pallor, pulselessness, paresthesias, poikilothermia, and paralysis) are classic signs of acute limb ischemia.
- The patient's history of **smoking**, **hypertension**, **diabetes**, and an **irregular pulse** (suggesting atrial fibrillation) are significant risk factors for **thromboembolism**, which is a common cause of acute limb ischemia.
*Buerger's disease*
- This condition primarily affects **small and medium-sized arteries and veins** in the limbs and is strongly associated with **heavy tobacco use**.
- However, it typically presents with **distal extremity ischemia**, superficial phlebitis, and Raynaud's phenomenon, rather than the sudden, severe, large vessel occlusion described here.
*Leriche syndrome*
- This syndrome involves **atherosclerotic occlusion of the distal aorta** at or just below the renal arteries, affecting both lower limbs.
- It classically presents with a triad of **bilateral buttock/thigh claudication**, **impotence**, and **absent femoral pulses**, which does not align with the unilateral symptoms and specific pulse deficits described in the case.
*CREST syndrome*
- CREST (Calcinosis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly, Telangiectasias) is a subtype of **systemic sclerosis**, a **connective tissue disease**.
- Its symptoms are unrelated to the acute vascular event presented, which involves sudden limb ischemia.
*Deep vein thrombosis*
- DVT primarily involves the formation of a **blood clot in a deep vein**, leading to symptoms like **swelling**, **pain**, and **redness** in the affected limb.
- It does not typically cause the **acute pallor**, **coldness**, **pulselessness**, and severe neurologic deficits (tingling, weakness) seen with arterial occlusion.
Question 9: A 31-year-old man presents to the Emergency Department with severe left leg pain and paresthesias 4 hours after his leg got trapped by the closing door of a bus. Initially, he had a mild pain which gradually increased to unbearable levels. Past medical history is noncontributory. In the Emergency Department, his blood pressure is 130/80 mm Hg, heart rate is 87/min, respiratory rate is 14/min, and temperature is 36.8℃ (98.2℉). On physical exam, his left calf is firm and severely tender on palpation. The patient cannot actively dorsiflex his left foot, and passive dorsiflexion is limited. Posterior tibial and dorsalis pedis pulses are 2+ in the right leg and 1+ in the left leg. Axial load does not increase the pain. Which of the following is the best next step in the management of this patient?
A. Lower limb CT scan
B. Lower limb ultrasound
C. Splinting and limb rest
D. Fasciotomy (Correct Answer)
E. Lower limb X-ray in two projections
Explanation: ***Fasciotomy***
- The patient presents with classic signs and symptoms of **acute compartment syndrome**, including unrelieved pain by analgesics, paresthesias, pain with passive stretching, and a tense compartment due to the bus door trauma.
- **Fasciotomy** is the definitive and urgent treatment to relieve pressure within the muscle compartments, prevent muscle ischemia, and avoid permanent nerve damage or limb loss.
*Lower limb CT scan*
- A **CT scan** is primarily used to evaluate bony structures and soft tissue injuries but is not the most immediate or definitive diagnostic tool for acute compartment syndrome.
- Delaying **fasciotomy** for imaging in a clear case of compartment syndrome can lead to irreversible damage.
*Lower limb ultrasound*
- **Ultrasound** can assess vascular flow and some soft tissue aspects but is not accurate or rapid enough for diagnosing compartment syndrome.
- It would not provide the necessary information to guide urgent surgical intervention.
*Splinting and limb rest*
- This approach is appropriate for fractures or soft tissue injuries without compartment syndrome; however, in acute compartment syndrome, **splinting or limb rest** will worsen the condition.
- **Immobilization** and elevation are contraindicated as they can further decrease blood flow and increase compartment pressure.
*Lower limb X-ray in two projections*
- An **X-ray** is useful for ruling out fractures but will not provide information about compartment pressure or muscle viability.
- While a fracture can sometimes cause compartment syndrome, the immediate concern here is the compartment syndrome itself, for which **X-rays** are not diagnostic.
Question 10: Two hours after undergoing a left femoral artery embolectomy, an obese 63-year-old woman has severe pain, numbness, and tingling of the left leg. The surgery was without complication and peripheral pulses were weakly palpable postprocedure. She has type 2 diabetes mellitus, peripheral artery disease, hypertension, and hypercholesterolemia. Prior to admission, her medications included insulin, enalapril, carvedilol, aspirin, and rosuvastatin. She appears uncomfortable. Her temperature is 37.1°C (99.3°F), pulse is 98/min, and blood pressure is 132/90 mm Hg. Examination shows a left groin surgical incision. The left lower extremity is swollen, stiff, and tender on palpation. Dorsiflexion of her left foot causes severe pain in her calf. Femoral pulses are palpated bilaterally. Pedal pulses are weaker on the left side as compared to the right side. Laboratory studies show:
Hemoglobin 12.1
Leukocyte count 11,300/mm3
Platelet count 189,000/mm3
Serum
Glucose 222 mg/dL
Creatinine 1.1 mg/dL
Urinalysis is within normal limits. Which of the following is the most likely cause of these findings?
A. Reperfusion injury (Correct Answer)
B. Cellulitis
C. Cholesterol embolism
D. Deep vein thrombosis
E. Rhabdomyolysis
Explanation: ***Reperfusion injury***
- The patient's symptoms of **severe pain, numbness, and tingling** in the left leg following an embolectomy, along with **swelling, stiffness, and tenderness** of the extremity, and pain on passive dorsiflexion (**pain with passive stretch**), are classic signs of **acute compartment syndrome**.
- In this context, compartment syndrome is caused by **reperfusion injury** following prolonged limb ischemia. When blood flow is restored after prolonged ischemia, the reperfusion causes **oxidative stress, inflammatory mediator release, and increased capillary permeability**, leading to **tissue edema and elevated intracompartmental pressure** that compresses nerves and vessels.
- The **2-hour timeline** post-embolectomy and the clinical triad of pain out of proportion, pain with passive stretch, and paresthesias make reperfusion injury leading to compartment syndrome the most likely diagnosis.
*Cellulitis*
- While cellulitis causes **pain, swelling, and redness**, it typically has a more **gradual onset** and is associated with warmth, erythema, and signs of infection.
- The **acute onset** (2 hours post-surgery), **severe neurologic symptoms** (numbness, tingling), and **pain with passive stretch** are not characteristic of cellulitis.
- The absence of fever, significant leukocytosis, or spreading erythema makes cellulitis unlikely.
*Cholesterol embolism*
- **Cholesterol emboli** can occur after vascular procedures and typically present with **livedo reticularis**, **"blue toe" syndrome**, **renal impairment**, or **eosinophilia**.
- While possible after arterial manipulation, the acute presentation with signs of **elevated compartment pressure** (pain with passive stretch, swelling, paresthesias) points to a pressure-related compartment issue rather than distal microembolization.
*Deep vein thrombosis*
- **DVT** causes **unilateral leg swelling, pain, and tenderness** but typically presents with a more **gradual onset** over hours to days.
- DVT would not explain the **acute severe pain with passive stretch**, **rapid neurologic symptoms** (paresthesias), or the **compartment syndrome findings** seen immediately (2 hours) post-procedure.
- The clinical picture of acute compartment syndrome better fits ischemia-reperfusion injury.
*Rhabdomyolysis*
- **Rhabdomyolysis** involves muscle breakdown due to prolonged ischemia or trauma and is characterized by **elevated creatinine kinase (CK)**, **myoglobinuria**, and potentially **acute kidney injury**.
- While rhabdomyolysis can occur **secondary to** both the initial ischemia and subsequent compartment syndrome, it is a **consequence or complication** rather than the **primary cause** of the acute compartment syndrome findings.
- The immediate clinical presentation (severe pain with passive stretch, paresthesias, swelling) reflects **elevated intracompartmental pressure from reperfusion injury**, not rhabdomyolysis itself.
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