CRNA PRACTICE EXAM 170
QUESTIONS COMPLETE
Question 1: A patient with severe aortic stenosis becomes hypotensive after
induction. Which hemodynamic goal is most important to preserve coronary perfusion?
Choices:
1) Maintain adequate diastolic arterial pressure 2) Reduce systemic vascular resistance 3) Increase heart rate above 110/min 4) Decrease preload to limit ventricular work
Correct Answer: Maintain adequate diastolic arterial pressure
Explanation: Severe aortic stenosis creates a �xed left ventricular out�ow obstruction.Coronary perfusion depends heavily on adequate aortic diastolic pressure, so maintaining systemic vascular resistance and diastolic pressure is a key goal while avoiding marked tachycardia or hypovolemia.Page 1
Question 2: Which change shifts the oxyhemoglobin dissociation curve to the right?
Choices:
1) Decreased temperature 2) Increased hydrogen ion concentration 3) Decreased 2,3-DPG 4) Fetal hemoglobin
Correct Answer: Increased hydrogen ion concentration
Explanation: Acidosis increases hydrogen ion concentration and decreases hemoglobin a�nity for oxygen, shifting the curve to the right and facilitating oxygen unloading to tissues.Hypothermia, decreased 2,3-DPG, and fetal hemoglobin shift the curve left.
Question 3: During positive-pressure ventilation, which physiologic change most
directly reduces venous return?
Choices:
1) Increased left ventricular afterload 2) Decreased pulmonary vascular resistance at all lung volumes 3) Increased intrathoracic pressure 4) Increased abdominal venous capacitance
Correct Answer: Increased intrathoracic pressure
Explanation: Positive-pressure ventilation increases intrathoracic pressure, which decreases the pressure gradient for systemic venous return to the right atrium. The e�ect can reduce preload and cardiac output, especially in hypovolemic patients.Page 2
Question 4: A patient with chronic hypercapnia has renal compensation. Which
�nding is most expected?
Choices:
1) Decreased serum bicarbonate 2) Decreased PaCO2 3) Increased anion gap from respiratory acidosis alone 4) Increased serum bicarbonate
Correct Answer: Increased serum bicarbonate
Explanation: With chronic respiratory acidosis, the kidneys retain bicarbonate and increase acid excretion. Therefore serum bicarbonate rises as compensation for the persistently elevated PaCO2.
Question 5: Which cerebral variable is most predictably decreased by acute
hypocapnia?
Choices:
1) Cerebral blood �ow 2) Cerebral vascular resistance 3) Cerebral oxygen extraction ratio 4) Cerebral metabolic rate from neuronal activity
Correct Answer: Cerebral blood �ow
Explanation: Acute hypocapnia causes cerebral vasoconstriction, increasing cerebrovascular resistance and decreasing cerebral blood �ow. The e�ect can lower intracranial pressure but excessive hypocapnia risks cerebral ischemia.Page 3