WBR286
| Author | [[PageAuthor::Gonzalo A. Romero, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 2 CK |
| Main Category | MainCategory::Internal medicine, MainCategory::Surgery |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology, SubCategory::Musculoskeletal/Rheumatology, SubCategory::Surgery, SubCategory::Electrolytes |
| Prompt | [[Prompt::A 73-year-old male is brought to the ER after being involved in a car accident. The firemen and paramedics invested 30 minutes to get him out of the car. After removing him from the car, they noticed a crush injury on the right distal arm, forearm and arm. His vital signs upon arrival are Temp 37C, 20 respirations/min, 130/86 mmHg, 87bpm. The patient complaints of paresthesias and pain on the right upper extremity. Physical examination is remarkable for multiple bruises on the right upper extremity, pallor, radial and ulnar pulses 2+, muscle strength II/IV. An initial radiologic survey does not reveal any fractures or internal bleeding. An EKG is shown below. Which of the following is the best next step when managing this patient to improve survival?
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| Answer A | AnswerA::Calcium gluconate |
| Answer A Explanation | [[AnswerAExp::Correct.Calcium supplementation (calcium gluconate 10% (10ml), preferably through a central venous catheter as the calcium may cause phlebitis) does not lower potassium but decreases myocardial excitability, protecting against life threatening arrhythmias.]] |
| Answer B | AnswerB::Normal saline |
| Answer B Explanation | [[AnswerBExp::Incorrect.Hydration is the best initial step in any patient following trauma in order to maintain the cardiac output. This patient does not have any signs of bleeding and is hemodinamically stable.]] |
| Answer C | AnswerC::Sodium bicarbonate |
| Answer C Explanation | [[AnswerCExp::Incorrect. Bicarbonate therapy (e.g. 1 ampule (45mEq) infused over 5 minutes) is effective in cases of metabolic acidosis. The bicarbonate ion will stimulate an exchange of cellular H+ for Na+, thus leading to stimulation of the sodium-potassium ATPase. It will not prevent acutely the development of arrhythmias.]] |
| Answer D | AnswerD::Mannitol |
| Answer D Explanation | [[AnswerDExp::Incorrect.It is an osmotic diuretic used to force diuresis and protect from the myoglobinuria damage. It does not prevent arrhythmias following crush injury-related hyperkalemia.]] |
| Answer E | AnswerE::Fasciotomy |
| Answer E Explanation | [[AnswerEExp::Incorrect. It is the surgical treatment of choice in compartment syndrome. However, following a crush injury, the rise in potasium could lead to fatal arrythmias, which should be treated initially with calcium gluconate.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::This elderly patient was involved in a car accident getting his upper extremity injured in a crush accident. He is hemodinamically stable. He has signs of compartment syndrome: pallor, paralysis, paresthesias, paralysis. His distal radial and ulnar pulses are strong (2+), but this sign is not enough to rule out compartment syndrome; the pulse is the last sign that appears in a compartment syndrome. Following a crush injury, the muscles get injured releasing myoglobin and potassium, which leads to hyperkalemia and myoglobinemia. The myoglobin is filtered through the kidney causing myoglobinuria which can ultimately cause renal failure. The hyperkalemia suspected in this patient following the muscle injury should be treated with calcium gluconate to establize the cardiac membrane in order to prevent arrhythmia which can lead to death.
Educational Objective: compartment syndrome manifests by pain, pallor, paresthesias, paralysis and pulseless. The pulse is last to disappear and is a sign of irreversible muscle damage. Management of the compartment syndrome include the following:
Educational Objective: |
| Approved | Approved::No |
| Keyword | WBRKeyword::Compartment syndrome, WBRKeyword::hyperkalemia, WBRKeyword::fasciotomy |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |