Respiratory Physiology
Anesthesia, Chapter 57
1. In zone 1 of the lung the following relationships exist:
- PA>Ppa>Ppv
- Ppa>PA>Ppv
- Ppa>Ppv>PA
- Ppa>Pisf>Ppv>PA
- PA>Ppv>Ppa
2. In zone 2 of the lung the following relationships exist:
- PA>Ppa>Ppv
- Ppa>PA>Ppv
- Ppa>Ppv>PA
- Ppa>Pisf>Ppv>PA
- PA>Ppv>Ppa
3. In zone 3 of the lung the following relationships exist:
- PA>Ppa>Ppv
- Ppa>PA>Ppv
- Ppa>Ppv>PA
- Ppa>Pisf>Ppv>PA
- PA>Ppv>Ppa
4. In zone 4 of the lung the following relationships exist:
- PA>Ppa>Ppv
- Ppa>PA>Ppv
- Ppa>Ppv>PA
- Ppa>Pisf>Ppv>PA
- PA>Ppv>Ppa
5. Blood flow is governed by pulmonary arterio-venous pressure difference in:
- Zone 1
- Zone 2
- Zone 3
- Zone 4
- None of the above
6. Pleural pressure (Ppl) increases by cmH20 from the top to the bottom of the lung:
7. As a result of changes in pleural pressure, dependent alveoli have a volume that is:
- Four times greater than alveoli in superior regions
- Two times greater than alveoli in superior regions
- One third the size of alveoli in superior regions
- One fourth the size of alveoli in superior regions
- The same as alveoli in superior regions
8. True or false? Tidal volume is preferentially distributed to dependent alveoli because they are relatively more compliant than non-dependent alveoli.
9. The predominant stimulus for activation of hypoxic pulmonary vasoconstriction is:
- Increased PaCO2
- Decreased PaCO2
- Increased PaO2
- Decreased PaO2
- None of the above
10. A colleague who will be anesthetizing a patient for thoracotomy for an open wedge biopsy of his right lung approaches you for advice. The patient is a long-time smoker (1.2 pack-centuries) and is currently using home O2 therapy at night. Your associate plans to place a double lumen endotracheal tube for single lung ventilation intraoperatively. The patient will be placed in the left lateral decubitus position. Preop evaluation suggests he has very limited oxygenating capacity. Your colleague is concerned the patient may not tolerate the V/Q mismatch which he considers inevitable during single lung ventilation. Explain to your beleaguered peer why the intrapulmonary shunt he is concerned about may not be as significant as he fears.
11. It is August, 1999, you are now a staff anesthesiologist at a prestigious medical center (one of the only remaining fee for service practices in North America) You are supervising the anesthesia for a patient with long-standing mitral stenosis and COPD for clipping of a right middle cerebral aneurysm. All goes well during the case until just before emergence when, in order to maintain acceptable systemic blood pressures, nipride is started. The patient gradually begins to desaturate. After a quick, systematic survey of O2 supplies, circuit integrity, ET tube position, breath sounds, etc., the very capable anesthetist is still unable to identify the source of the patient's hypoxia and summons you. What explanation can you offer and what is your management plan?
12. You are caring for a patient with severe ARDs in the SICU. The patient has required high levels of PEEP to maintain marginally adequate oxygenation. You are called to the bedside by a very observant SICU nurse who has noted that the patient seems to have developed a right gaze preference. What may have happened and why?
13. Draw and label a spirometry tracing:
14. Define FRC.
15. Define closing capacity.
16. Define dynamic compliance.
17. Define static compliance.
18. Each of the following cannot be measured by simple spirometry EXCEPT:
- FRC
- ERV
- Residual volume
- Total lung volume
- Vital capacity
19. True or false? Surfactant is produced by type II pneumocytes.
20. During a normal VT (500 ml) breath, the transpulmonary pressure increases from 0 to 5 cmH2O. The product of the transpulmonary pressure and VT is 2,500 cmH2O-ml. This expression of the pressure volume relationship during breathing determines what variable of respiratory mechanics?
- Lung compliance
- Airway resistance
- Pulmonary elastance
- Work of breathing
- Closing capacity
21. You are anesthetizing a 65 kg patient with severe COPD for a laparoscopic cholecystectomy. Describe the ventilator settings you will use and your rationale for these choices. What if the patient did not have COPD but instead had a severe kyphoscoliosis?
22. True or false? Emphysematous lungs have significantly increased compliance when compared with normal lungs.
23. Closing capacity is reduced by:
- Supine position
- Smoking
- Obesity
- Aging
- None of the above
24. True or false? Under normal circumstances the closing volume of the lung is below lung volumes throughout all of tidal respiration and all airways remain open.
25. You are providing anesthesia for a very lengthy VBG. After much grunting and sweating, the surgeons have placed a large, self-retaining retractor, as well as several lap sponges in the cephalad portion of the field. The patient is in reverse Trendelenburg position. After the first three hours of the case, you observe that he has been gradually desaturating (initial O2 sats 99-100%; current sats 95-96%). Breath sounds are present bilaterally and unchanged, ETT position is unchanged, FIO2 (40%) and vent settings are unchanged. After filling the reservoir bag using the machine's flush valve, you hand ventilate the patient with two large breaths, holding at end-inspiration for several seconds. The patient's sats transiently improve. Why? What may be causing his desaturation? What maneuver(s) may help maintain better oxygenation?
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