Age-related changes in thermoregulation — MCQs

A 75-year-old woman presents with a sudden onset of weakness and difficulty walking. She also complains of nausea and palpitations. She was working in her garden about an hour ago when her problems started. The patient says she is feeling warm even though the emergency room is air-conditioned. Past medical history is significant for major depressive disorder (MDD), diagnosed 5 years ago, hypertension, and osteoporosis. Current medications are aspirin, lisinopril, alendronate, calcium, venlafaxine, and a vitamin D supplement. Her pulse is 110/min, respiratory rate is 22/min, and blood pressure is 160/100 mm Hg. Physical examination is unremarkable. A noncontrast CT scan of the head, electrocardiogram (ECG), and routine laboratory tests are all normal. Which of the following most likely accounts for this patient's condition?

An 84-year-old man presents to the emergency department for a loss of consciousness. The patient states that he was using the bathroom when he lost consciousness and fell, hitting his head on the counter. The patient has a past medical history of diabetes, hypertension, obesity, factor V leiden, constipation, myocardial infarction, and vascular claudication. His current medications include lisinopril, atorvastatin, valproic acid, propranolol, insulin, metformin, and sodium docusate. The patient denies use of illicit substances. His temperature is 99.5°F (37.5°C), blood pressure is 167/98 mmHg, pulse is 90/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam reveals an elderly man sitting comfortably in his stretcher. Cardiac exam reveals a systolic murmur heard at the right upper sternal border that radiates to the carotids. Pulmonary exam reveals mild bibasilar crackles. Neurological exam reveals 5/5 strength in his upper and lower extremities with normal sensation. The patient's gait is mildly unstable. The patient is unable to give a urine sample in the emergency department and states that he almost fainted again when he tried to. Which of the following is the most likely diagnosis?

A 70-year-old man with a history of Alzheimer dementia presents to the emergency department with a change in his behavior. The patient has been more confused recently and had a fever. Upon presentation, he is too confused to answer questions. His temperature is 103°F (39.4°C), blood pressure is 102/68 mmHg, pulse is 157/min, respirations are 22/min, and oxygen saturation is 99% on room air. The patient is given 3 liters of IV fluids and acetaminophen and his vitals improve. He is also less confused. The patient is asking where he is and becomes combative and strikes a nurse when he finds out he has to be admitted to the hospital. He is given diphenhydramine for sedation and put in soft restraints. His mental status subsequently worsens and he becomes much more aggressive, spitting at nurses and attempting to bite his restraints. He also complains of abdominal pain. A post void residual volume is notable for a urine volume of 750 mL. Which of the following is the etiology of this patient's recent mental status change?

A 39-year-old female presents to the clinic with the complaints of dry skin for a few months. She adds that she also has constipation for which she started eating vegetables and fruits but with no improvement. She lives with her husband and children who often complain when she turns the air conditioning to high as she cannot tolerate low temperatures. She has gained 5 kgs (11.2 lb) since her last visit 2 months back although her diet has not changed much. Her past medical history is relevant for cardiac arrhythmias and diabetes. She is on several medications currently. Her temperature is 98.6° F (37° C), respirations are 15/min, pulse is 57/min and blood pressure is 132/98 mm Hg. A physical examination is within normal limits. Thyroid function test results are given below: Serum TSH: 13.0 μU/mL Thyroxine (T4): 3.0 μg/dL Triiodothyronine (T3): 100 ng/dL Which of the following medications is most likely to be responsible for her symptoms?

An infant boy of unknown age and medical history is dropped off in the emergency department. The infant appears lethargic and has a large protruding tongue. Although the infant exhibits signs of neglect, he is in no apparent distress. The heart rate is 70/min, the respiratory rate is 30/min, and the temperature is 35.7°C (96.2°F). Which of the following is the most likely cause of the patient’s physical exam findings?

A 33-year-old man presents to the emergency department acutely confused. The patient was found down at a local construction site by his coworkers. The patient has a past medical history of a seizure disorder and schizophrenia and is currently taking haloperidol. He had recent surgery 2 months ago to remove an inflamed appendix. His temperature is 105°F (40.6°C), blood pressure is 120/84 mmHg, pulse is 150/min, respirations are 19/min, and oxygen saturation is 99% on room air. Physical exam is notable for a confused man who cannot answer questions. His clothes are drenched in sweat. He is not making purposeful movements with his extremities although no focal neurological deficits are clearly apparent. Which of the following is the most likely diagnosis?

A previously healthy 44-year-old man is brought by his coworkers to the emergency department 45 minutes after he became light-headed and collapsed while working in the boiler room of a factory. He did not lose consciousness. His coworkers report that 30 minutes prior to collapsing, he told them he was nauseous and had a headache. The patient appears sweaty and lethargic. He is not oriented to time, place, or person. The patient’s vital signs are as follows: temperature 41°C (105.8°F); heart rate 133/min; respiratory rate 22/min; and blood pressure 90/52 mm Hg. Examination shows equal and reactive pupils. Deep tendon reflexes are 2+ bilaterally. His neck is supple. A 0.9% saline infusion is administered. A urinary catheter is inserted and dark brown urine is collected. The patient’s laboratory test results are as follows: Laboratory test Blood Hemoglobin 15 g/dL Leukocyte count 18,000/mm3 Platelet count 51,000/mm3 Serum Na+ 149 mEq/L K+ 5.0 mEq/L Cl- 98 mEq/L Urea nitrogen 42 mg/dL Glucose 88 mg/dL Creatinine 1.8 mg/dL Aspartate aminotransferase (AST, GOT) 210 Alanine aminotransferase (ALT, GPT) 250 Creatine kinase 86,000 U/mL Which of the following is the most appropriate next step in patient management?

A group of investigators is studying thermoregulatory adaptations of the human body. A subject is seated in a thermally insulated isolation chamber with an internal temperature of 48°C (118°F), a pressure of 1 atmosphere, and a relative humidity of 10%. Which of the following is the primary mechanism of heat loss in this subject?

A 45-year-old man presents to the physician with complaints of burning pain in both feet and lower legs for 3 months. He reports that the pain is especially severe at night. He has a history of diabetes mellitus for the past 5 years, and he frequently skips his oral antidiabetic medications. His temperature is 36.9°C (98.4°F), heart rate is 80/min, respiratory rate is 15/min, and blood pressure is 120/80 mm Hg. His weight is 70 kg (154.3 lb) and height is 165 cm (approx. 5 ft 5 in). The neurologic examination reveals loss of sensations of pain and temperature over the dorsal and ventral sides of the feet and over the distal one-third of both legs. Proprioception is normal; knee jerks and ankle reflexes are also normal. The tone and strength in all muscles are normal. The hemoglobin A1C is 7.8%. Involvement of what type of nerve fibers is the most likely cause of the patient’s symptoms?

A 42-year-old man undergoes therapeutic hypothermia (target temperature 33°C/91.4°F) following cardiac arrest with return of spontaneous circulation. During the cooling phase, he develops shivering, which increases oxygen consumption and interferes with target temperature achievement. He is already on sedation and neuromuscular blockade is being considered. Evaluate the most appropriate management strategy considering both efficacy and safety.