Chapter 17 Anesthetic Monitoring
1. What is the purpose of intraoperative patient monitoring?
2. What are some monitors that have been mandated for use by the American Society of Anesthesiologists? How frequently is it mandated that intraoperative blood pressure be measured?
Electrocardiographic Monitoring
3. What are some potential intraoperative problems during anesthesia that can be detected by an anesthesiologist through the use of an electrocardiogram?
4. Which lead is selected on the electrocardiogram for continuous tracing on the monitor to best detect cardiac dysrhythmias? Why?
5. Which lead is selected on the electrocardiogram for continuous tracing on the monitor to best detect inferior wall myocardial ischemia? Which lead is selected for continuous tracing on the monitor to best detect anterior or lateral wall myocardial ischemia?
Systemic Blood Pressure Monitoring
6. How does an automated oscillometric blood pressure measuring device, such as the Dinamap, work?
7. What is the appropriate-sized cuff for use with an automated oscillometric blood pressure measuring device?
8. When using an automated oscillometric blood pressure measuring device, will the blood pressure be falsely high or low with a cuff that is too small? When using an automated oscillometric blood pressure measuring device, will the blood pressure be falsely high or low with a cuff that is too loose?
9. What is a potential problem that can result from too frequent cycling of an automated oscillometric blood pressure measuring device?
10. What are some possible indications for intraarterial blood pressure monitoring?
11. What are some arteries that may be used for intraarterial blood pressure monitoring? Which of these is most commonly selected?
12. How does the intraarterial blood pressure waveform change with increasing distance from the heart?
Central Venous Pressure Monitoring
13. What are some indications for the placement of a central venous catheter?
14. What veins are used for central venous access? What are some potential complications of the cannulation of veins for central access?
15. Which is the preferred jugular vein for cannulation? Why?
16. What are some advantages and disadvantages of cannulation of the internal jugular vein over other central veins?
17. What are some advantages and disadvantages of cannulation of the subclavian vein over other central veins?
18. What does the central venous waveform look like? What do each of the peaks and descents represent relative to the cardiac cycle?
19. Why is the central venous pressure able to be used to estimate a patient’s intravascular fluid volume status?
20. Under which circumstances does central venous pressure not estimate a patient’s intravascular fluid volume status? What invasive monitor can be used instead of a central venous catheter under these conditions?
Pulmonary Artery Catheter Monitoring
21. Name six possible indications for the placement of a pulmonary artery catheter. What information can be obtained regarding the patient’s status with the use of a pulmonary artery catheter?
22. Of what is the pulmonary capillary wedge pressure a reflection? What other measurement derived by the pulmonary artery catheter can also be used in lieu of the pulmonary capillary wedge pressure?
23. How is estimation of the cardiac output accomplished through the use of a pulmonary artery catheter?
24. What are some potential complications of pulmonary artery catheterization?
25. Please complete the following table illustrating the usefulness of central venous catheters and pulmonary artery catheters in the evaluation of various hemodynamic disorders (PAEDP, pulmonary artery end-diastolic pressure; PAOP, pulmonary artery occlusion pressure).
Echocardiographic Monitoring
26. What is some information that can be derived intraoperatively through the use of a transesophageal echocardiogram?
27. What is the difference between M-mode and B-mode echocardiography?
28. When would one use continuous-wave Doppler as opposed to using pulsed-wave Doppler? What is the Nyquist limit?
Pulse Oximetry Monitoring
29. How does a pulse oximeter work?
30. Enumerate five factors that influence the accuracy of pulse oximetry.
31. Is the SpO2 read by the pulse oximeter falsely high or falsely low in the presence of carboxyhemoglobin?
32. What is the SpO2 read by the pulse oximeter in the presence of methemoglobinemia?
33. What is the SpO2 read by the pulse oximeter in the presence of intravenous dyes?
Electrophysiologic Monitoring
34. What is an evoked potential? What are some evoked potentials that can be monitored?
35. What are some intraoperative uses of evoked potentials? What is the most common procedure for which evoked potentials are monitored intraoperatively?
36. How do evoked potentials appear when the patient is under general anesthesia? What is the potential problem with this?
37. What are some factors that may limit the usefulness of evoked potentials in the intraoperative period?
38. The integrity of which spinal cord neurologic tissue is monitored by somatosensory evoked potentials and motor evoked potentials?
Capnography Monitoring
40. Please refer to Figure 20-10. What portion of the ventilatory cycle is represented by each letter in the figure?
41. What does the absence of carbon dioxide in a patient’s exhaled gases indicate during endotracheal intubation? What does the absence of carbon dioxide in a person’s exhaled gases indicate after proper and confirmed endotracheal intubation?
42. What are some possible causes of a decrease in the concentration of carbon dioxide in a patient’s exhaled gases?
43. What are some possible causes of an increase in the concentration of carbon dioxide in a patient’s exhaled gases?
44. How does the end-tidal carbon dioxide concentration measured on a capnogram compare with the arterial carbon dioxide concentration? Why?
Electroencephalographic Monitoring
45. What are some intraoperative uses of an electroencephalogram?
46. What factors may influence the tracings obtained by an intraoperative electroencephalogram?
47. What is the bispectral index monitor?
48. What are some potential clinical uses of a bispectral index monitor? What are its limitations?
Inhaled Gas Monitoring
52. What are some methods by which the exhaled concentrations of multiple gases, including respiratory and anesthetic gases, may be measured?
53. What are some advantages and disadvantages of mass spectrometry techniques for measuring a patient’s exhaled gases?
54. What are some advantages and disadvantages of Raman spectrometry techniques for measuring a patient’s exhaled gases?
Answers*
1. The primary purpose of intraoperative patient monitoring is to gather data regarding the physiologic status of the patient. Monitoring provides the anesthesiologist with the information to respond appropriately to any salutary or adverse physiologic changes. In addition, the patient’s response to the therapeutic interventions can be assessed. (320)
