WBR0233

Author	[[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Inpatient Facilities
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 73 year old male is in ICU on ventilator for three days after cardiac arrest. He had a past history of diabetes and CABG performed 7 years ago. Three days ago he collapsed at home, after which he was intubated and put on ventilator after prolonged hours of CPR in the hospital. Still he completely relies on ventilator support. He is unresponsive to verbal and painful stimuli. His vitals are BP: 110/60 mmHg, pulse 64/min and temperature is 99F. Which of the following doesn’t meet the prerequisite before considering the patient for the diagnosis of brain death?]]
Answer A	AnswerA::Core temperature of 36ºC
Answer A Explanation	[[AnswerAExp::Incorrect : Core temperature >36ºC (97ºF) is an important criteria. Hypothermia may also confound the diagnostic assessment of brain death and can also delay the increase in PaCO2 necessary to complete the apnea test. A warming blanket is required to achieve normothermia in many patients with brain death. There is little evidence base for a choice of threshold temperature.]]
Answer B	AnswerB::Absent jaw jerk
Answer B Explanation	[[AnswerBExp::Incorrect : Absent pupillary light reflex, corneal reflexes, oculovestibular reflexes (caloric responses), jaw jerk, gag, sucking, or rooting reflex, cough with tracheal suctioning, sucking or rooting reflexes suggest an irreversible absence of cerebral or brainstem response.]]
Answer C	AnswerC::Serum potassium of 3.5mEq/L
Answer C Explanation	[[AnswerCExp::Incorrect : Serum potassium is within normal limits (3.5-4.5mEq/L) and hence no severe electrolyte disturbances.]]
Answer D	AnswerD::Flexion at the hip, knee, and ankle with foot stimulation
Answer D Explanation	[[AnswerDExp::Incorrect : Movements originating from the spinal cord or peripheral nerve may occur in brain death. These are common and may be triggered by tactile stimuli or occur spontaneously. Babinski sign is one among those reflexes when there is no cerebral inhibitory response on spinal cord.]]
Answer E	[[AnswerE::Systolic blood pressure of >90 mmHg]]
Answer E Explanation	[[AnswerEExp::Correct : Systolic blood pressure of >90 mmHg is incorrect as systolic blood pressure >100 mg Hg is a pre-requisite.]]
Right Answer	RightAnswer::E
Explanation	[[Explanation::Brain death implies the permanent absence of cerebral and brainstem functions. There are a number of prerequisites before one can begin considering a patient "brain dead" . • Clinical or neuroimaging evidence of an acute CNS catastrophe that is compatible with the clinical diagnosis of brain death, ie, the cause of brain death should be known. • Exclusion of complicating medical conditions that may confound clinical assessment (no severe electrolyte, acid-base, endocrine, or circulatory disturbance (ie, shock). • No drug intoxication or poisoning, which may confound the clinical assessment. • Core temperature >36ºC (97ºF). • Normal systolic blood pressure >100 mg Hg. Vasopressors may be required. Educational Objective: References: ]]
Approved	Approved::Yes
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