Acid-base balance — MCQs

A 68-year-old man comes to the physician because of fatigue and muscle cramps for the past 4 weeks. He has also noticed several episodes of tingling in both hands. He has not had fever or nausea. He has had a chronic cough for 10 years. He has chronic bronchitis, hypertension, and osteoarthritis of both knees. His father died from lung cancer. Current medications include salbutamol, ibuprofen, and ramipril. He has smoked 1 pack of cigarettes daily for 45 years. He is 175 cm (5 ft 9 in) tall and weighs 68 kg (163 lb); BMI is 22 kg/m2. His temperature is 36.7°C (98°F), pulse is 60/min, and blood pressure is 115/76 mm Hg. While measuring the patient's blood pressure, the physician observes carpopedal spasm. Cardiopulmonary examination shows no abnormalities. His hematocrit is 41%, leukocyte count is 5,800/mm3, and platelet count is 195,000/mm3. Serum alkaline phosphatase activity is 55 U/L. An ECG shows sinus rhythm with a prolonged QT interval. Which of the following is the most likely underlying cause of this patient's symptoms?

A 30-year-old man is brought to the emergency room by ambulance after being found unconscious in his car parked in his garage with the engine running. His wife arrives and reveals that his past medical history is significant for severe depression treated with fluoxetine. He is now disoriented to person, place, and time. His temperature is 37.8 deg C (100.0 deg F), blood pressure is 100/50 mmHg, heart rate is 100/min, respiratory rate is 10/min, and SaO2 is 100%. On physical exam, there is no evidence of burn wounds. He has moist mucous membranes and no abnormalities on cardiac and pulmonary auscultation. His respirations are slow but spontaneous. His capillary refill time is 4 seconds. He is started on 100% supplemental oxygen by non-rebreather mask. His preliminary laboratory results are as follows: Arterial blood pH 7.20, PaO2 102 mm Hg, PaCO2 23 mm Hg, HCO3 10 mm Hg, WBC count 9.2/µL, Hb 14 mg/dL, platelets 200,000/µL, sodium 137 mEq/L, potassium 5.0 mEq/L, chloride 96 mEq/L, BUN 28 mg/dL, creatinine 1.0 mg/dL, and glucose 120 mg/dL. Which of the following is the cause of this patient's acid-base abnormality?

Your test subject is a stout 52-year-old gentleman participating in a study on digestion. After eating a platter of meat riblets and beef strips, the test subject's digestive tract undergoes vast hormonal changes. Which of the following changes likely occurred in this patient as a result of the meal?

A 40-year-old man with a history of type I diabetes presents to the emergency room in respiratory distress. His respirations are labored and deep, and his breath odor is notably fruity. Which of the following laboratory results would you most expect to find in this patient?

A 68-year-old man is brought to the emergency department by ambulance after he fainted in the supermarket. He recently had 2 days of gastroenteritis, but did not come to the hospital for treatment. He also recently arrived in Denver for a vacation, but normally lives in Florida. His past medical history is significant for morbid obesity and heavy alcohol use. Arterial blood gas and serum chemistry results are shown below: Sodium: 138 mEq/L Chloride: 121 mEq/L Bicarbonate: 8 mEq/L pH: 7.25 PaCO2: 20 mmHg Which of the following etiologies is most likely responsible for this patient's findings?

A 34-year-old female comes to the ED complaining of epigastric pain and intractable nausea and vomiting for the last 24 hours. Her vitals are as follows: Temperature 38.1 C, HR 97 beats/minute, BP 90/63 mm Hg, RR 12 breaths/minute. Arterial blood gas and labs are drawn. Which of the following sets of lab values is consistent with her presentation?

A 57-year-old woman comes to the emergency department because of dizziness, nausea, and vomiting for 4 days. Her temperature is 37.3°C (99.1°F), pulse is 100/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. Physical examination shows no abnormalities. Arterial blood gas analysis on room air shows: pH 7.58 PCO2 43 mm Hg PO2 96 mm Hg HCO3- 32 mEq/L The most appropriate next step in diagnosis is measurement of which of the following?

A 72-year-old man being treated for benign prostatic hyperplasia (BPH) is admitted to the emergency department for 1 week of dysuria, nocturia, urge incontinence, and difficulty initiating micturition. His medical history is relevant for hypertension, active tobacco use, chronic obstructive pulmonary disease, and BPH with multiple urinary tract infections. Upon admission, he is found with a heart rate of 130/min, respiratory rate of 19/min, body temperature of 39.0°C (102.2°F), and blood pressure of 80/50 mm Hg. Additional findings during the physical examination include decreased breath sounds, wheezes, crackles at the lung bases, and intense right flank pain. A complete blood count shows leukocytosis and neutrophilia with a left shift. A sample for arterial blood gas analysis (ABG) was taken, which is shown below. Laboratory test Serum Na+ 140 mEq/L Serum Cl- 102 mEq/L Serum K+ 4.8 mEq/L Serum creatinine (SCr) 2.3 mg/dL Arterial blood gas pH 7.12 Po2 82 mm Hg Pco2 60 mm Hg SO2% 92% HCO3- 12.0 mEq/L Which of the following best explains the patient’s condition?

A 22-year-old female college student presents to the emergency department due to severe pain in her stomach after an evening of heavy drinking with her friends. The pain is located in the upper half of the abdomen, is severe in intensity, and has an acute onset. She claims to have consumed a dozen alcoholic drinks. Her past medical history is unremarkable. She has recently completed an extremely low-calorie diet which resulted in her losing 10 kg (22 lb) of body weight. Her pulse is 130/min, respirations are 26/min, and blood pressure is 130/86 mm Hg. Examination reveals a visibly distressed young female with periumbilical tenderness. Her BMI is 23 kg/m2. Laboratory tests show: Arterial blood gas analysis pH 7.54 Po2 100 mm Hg Pco2 23 mm Hg HCO3- 22 mEq/L Serum Sodium 140 mEq/L Potassium 3.9 mEq/L Chloride 100 mEq/L Which of the following most likely caused her elevated pH?

A 24-year-old woman presents to the emergency department after she was found agitated and screaming for help in the middle of the street. She says she also has dizziness and tingling in the lips and hands. Her past medical history is relevant for general anxiety disorder, managed medically with paroxetine. At admission, her pulse is 125/min, respiratory rate is 25/min, and body temperature is 36.5°C (97.7°F). Physical examination is unremarkable. An arterial blood gas sample is taken. Which of the following results would you most likely expect to see in this patient?