Directions: The following exam consists of various types of questions designed to test the critical reasoning skills of the examinee. Answers are found on the following page, with rationales. This is a Twenty question test, with an allotted time of 45 minutes to indulge one's academic and clinical prowess.
             Questions 1-4 are based on the following scenario:
             A 55 year old male, medium body build of 90 Kg presents complaining of acute shortness of breath. He has a history of CHF and acute respiratory failure, he is agitated and disoriented. He has been placed on a ventilator two times during the past year. His medications include HCTZ, captopril, digoxin, and lasix. Paramedics have placed him in 100% O2 via Non-rebreathing mask, established an IV and administered 40 mg of Lasix IV enroute. He is cold, pale, and diaphoretic, with a BP of 200/110, HR 120, RR 48, rales are audible througout. ABG's are drawn, and the results are: pH - 7.3, PCO2 55, HCO3 24, PaO2 60.
             1. Why is this gentleman's PCO2 elevated?
             a. Not enough total ventilation (CNS/Respiratory muscle weakness)
             b. Too much total ventilation Dead Space (Rapid breathing)
             (1) d - The only reason for elevated PCO2 is an inadequate level of alveolar ventilation for the amount of CO2 produced and delivered to the lungs. Hypercapnea in this case is a combination of both. Since he is tachypneic his respiratory muscles are tiring, he is displaying mental status changes do to hypercarbia effects on the CNS. Because his RR is 48 he much of his VT ends up as alveolar dead space.
             2. Why is this gentleman's PaCO2 of concern to you clinically?
             a. Increased PaCO2 (if no compensatory increase in HCO3) results in fall in pH
             b. Increased PaCO2 results in a decrease in PaO2 unless FiO2 can increase enough to compensate
             c. The higher the PaCO2, the less well defended this pt is against a further decrease in VA
             e. His PaCO2 in ...