WBR0236
| Author | [[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 3 |
| Main Category | MainCategory::Emergency Room |
| Sub Category | SubCategory::Endocrine |
| Prompt | [[Prompt::A 23 yr old male came to the emergency department with complaints of headache and palpitations. By time you attended the patient, he is asymptomatic. He reveals three similar episodes in the past that resolved spontaneously. He was recently diagnosed with hypertension, but she is currently on no medications for that. On examniation, you see a anxious and diaphorectic person. Physcial examination reveals severe hand tremors and excessive sweating. His temperature is 36.7 C, blood pressure is 190/100 mmHg, pulse is 102/min and respiartions are 16/min. Her oxygen saturation is 97% on room air. The neck is supple without any jugular venous distension or thyroid enlargement. While waiting for the biochemical results, a slow infusion of labetolol is started. What would be the reaction to the treatment given to the patient?
A. Blood pressure will slowly increase B. Blood pressure will slowly decrease C. Blood pressure will rapidly decrease D. Blood pressure will rapidly increase E. Blood pressure will be the same]] |
| Answer A | AnswerA::Blood pressure will slowly increase |
| Answer A Explanation | AnswerAExp::'''Incorrect''' : The alpha and beta blocking property of labetolol does bring blood pressure very rapidly to the normal state |
| Answer B | AnswerB::Blood pressure will slowly decrease |
| Answer B Explanation | AnswerBExp::'''Incorrect''' : Blood pressure rapidly decreases when labetolol is administered in pheochromocytoma patients. |
| Answer C | AnswerC::Blood pressure will rapidly decrease |
| Answer C Explanation | AnswerCExp::'''Correct''' : Blood pressure rapidly decreases when labetolol is administered. |
| Answer D | AnswerD::Blood pressure will rapidly increase |
| Answer D Explanation | AnswerDExp::'''Incorrect''' : Blood pressure decreases and not increase. |
| Answer E | AnswerE::Blood pressure will be the same |
| Answer E Explanation | AnswerEExp::'''Incorrect''' : Blood pressure rapidly decreases when labetolol is administered. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Pheochromocytoma is a tumor of chromaffin tissue found either in the adrenal medulla or in extra-adrenal sites that secrete catecholamines. It presents with intermittent tachycardia, palpitations, chest pain, diaphoresis, hypertension, headache, tremor, and anxiety. A typical paroxysm of pheochromocytoma is described here and such paroxsyms will increase in severity overtime. Although intial treatment with beta-blockers is reasonable to control sympathetic overactivity, this approach is very dangerous. Never give beta blockade first; otherwise, unopposed alpha adrenergic stimulation will lead to refractory hypertension. Alpha blockers are the initial drug in the management of pheochromcytoma and beta blockers are added to control tremors and tachycardia. Drug such as labetolol, which has both alpha and beta blocking property does bring blood pressure very rapidly to the normal state. Its rapid onset of action (5 minutes or less) makes it useful in the treatment of hypertensive emergencies. Labetalol is safe in patients with active coronary disease, since it does not increase the heart rate. However, labetalol should not be used without prior adequate alpha-blockade in patients with hyperadrenergic states, such as pheochromocytoma and methamphetamine overdose, since unopposed, inadequately blocked alpha-adrenergic activity can lead to a further rise in blood pressure if beta blockade is not complete. Educational Objective: |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |