Respiratory alkalosis mechanisms and compensation — MCQs

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?

A 66-year-old man is brought to the emergency department by his daughter because of 3 days of fever, chills, cough, and shortness of breath. The cough is productive of yellow sputum. His symptoms have not improved with rest and guaifenesin. His past medical history is significant for hypertension, for which he takes hydrochlorothiazide. He has a 30-pack-year history of smoking. His temperature is 38.9 C (102.0 F), blood pressure 88/56 mm Hg, and heart rate 105/min. Following resuscitation with normal saline, his blood pressure improves to 110/70 mm Hg. His arterial blood gas is as follows: Blood pH 7.52, PaO2 74 mm Hg, PaCO2 28 mm Hg, and HCO3- 21 mEq/L. Which of the following acid-base disturbances best characterizes this patient's condition?

A 24-year-old male is brought in by ambulance to the emergency department after he was found unresponsive at home for an unknown length of time. Upon arrival, he is found to be severely altered and unable to answer questions about his medical history. Based on clinical suspicion, a panel of basic blood tests are obtained including an arterial blood gas, which shows a pH of 7.32, a pCO2 of 70, and a bicarbonate level of 30 mEq/L. Which of the following is most likely the primary disturbance leading to the values found in the ABG?

A 52-year-old man with a history of Type 1 diabetes mellitus presents to the emergency room with increasing fatigue. Two days ago, he ran out of insulin and has not had time to obtain a new prescription. He denies fevers or chills. His temperature is 37.2 degrees Celsius, blood pressure 84/56 mmHg, heart rate 100/min, respiratory rate 20/min, and SpO2 97% on room air. His physical exam is otherwise within normal limits. An arterial blood gas analysis shows the following: pH 7.25, PCO2 29, PO2 95, HCO3- 15. Which of the following acid-base disorders is present?

What is the primary mechanism for maintaining acid-base balance during prolonged vomiting?

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 25-year-old man is in the middle of an ascent up a mountain, at an elevation of about 4,500 meters. This is the 4th day of his expedition. His friend notices that in the last few hours, he has been coughing frequently and appears to be short of breath. He has used his albuterol inhaler twice in the past 4 hours, but it does not seem to help. Within the past hour, he has coughed up some frothy, slightly pink sputum and is now complaining of nausea and headache. Other than his asthma, which has been well-controlled on a steroid inhaler, he is healthy. Which of the following is the most likely cause of this man’s symptoms?

A 58-year-old man presents to the emergency department with a chief complaint of ringing in his ears that started several hours previously that has progressed to confusion. The patient denies any history of medical problems except for bilateral knee arthritis. He was recently seen by an orthopedic surgeon to evaluate his bilateral knee arthritis but has opted to not undergo knee replacement and prefers medical management. His wife noted that prior to them going on a hike today, he seemed confused and not himself. They decided to stay home, and roughly 14 hours later, he was no longer making any sense. Physical exam is notable for a confused man. The patient's vitals are being performed and his labs are being drawn. Which of the following is most likely to be seen on blood gas analysis?

A 27-year-old man presents to the emergency department with his family because of abdominal pain, excessive urination, and drowsiness since the day before. He has had type 1 diabetes mellitus for 2 years. He ran out of insulin 2 days ago. The vital signs at admission include: temperature 36.8°C (98.2°F), blood pressure 102/69 mm Hg, and pulse 121/min. On physical examination, he is lethargic and his breathing is rapid and deep. There is a mild generalized abdominal tenderness without rebound tenderness or guarding. His serum glucose is 480 mg/dL. Arterial blood gas of this patient will most likely show which of the following?

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?