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? ]]
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: Treatment of hyperkalemia. The first initial step is to provide calcium gluconate to prevent arrythmias. The following steps are also included as the management of hyperkalemia: insulin, dextrose 50, beta-2 agonists. Fasciotomy. This is the following step, which includes dissecting the skin through the fascia in order to release the pressure increased in the syndrome which is limiting the blood blow to the extremity. Hydration to protect the kidney from the myoglobinemia/myoglobinuria Osmotic diuretics (manitol) Soidum bicarbonate to alkalinize the urine to protect the kidney WikiDoc Mnemonic: 5 Ps within the comPartment syndrome: pain, pallor, paresthesia, paralysis and pulseless References: Master the Boards for Step 2CK See also: Compartment syndrome and Hyperkalemia Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Compartment syndrome, WBRKeyword::hyperkalemia, WBRKeyword::fasciotomy
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::