Chapter 25 Renal, Liver, and Biliary Tract Disease
Renal disease
1. What are some essential physiologic functions of the kidneys?
2. Name some factors that place patients at an increased risk of acute renal failure in the perioperative period.
3. What percent of the cardiac output normally goes to the kidneys? What fraction of this goes to the renal cortex?
4. Over what range of mean arterial blood pressures do renal blood flow and the glomerular filtration rate (GFR) remain constant? How is this accomplished by the kidneys? Why is it important?
5. Even during normal kidney autoregulatory function, what two factors can alter renal blood flow?
6. What is renin? What is the secretion of renin usually in response to? What effect does renin have on renal blood flow?
7. What is the physiologic effect of the secretion of renin?
8. What triggers the release of prostaglandins that are produced by the renal medulla? What is the effect of prostaglandins released by the renal medulla?
9. What is the renal effect of arginine vasopressin released by the hypothalamus?
10. What is glomerular filtration? What is glomerular filtration dependent on?
11. What is the normal hydrostatic pressure of the glomerular capillaries? What is the normal plasma oncotic pressure in the afferent and efferent arterioles?
12. What is the average normal rate of glomerular filtration?
13. About what percent of the fluid shift from glomerular filtration is reabsorbed from renal tubules and ultimately returned to the circulation?
14. How is the GFR influenced by the renal blood flow?
15. What are the three mechanisms upon which the renal clearance of drugs depends?
16. Name some tests used for the evaluation of renal function. How sensitive are tests of renal function?
17. What degree of renal disease can exist before renal function tests begin to indicate possible decreases in renal function?
18. What is the normal level of blood urea nitrogen (BUN)?
19. What factors may influence the BUN level?
20. Why does the BUN concentration increase in dehydrated states? What is the serum creatinine level under these circumstances?
21. What do BUN concentrations higher than 50 mg/dL almost always indicate?
22. What is the source of serum creatinine? How is the serum creatinine level related to the GFR?
23. Why might a normal creatinine level be seen in elderly patients despite a decreased GFR?
24. Why might normal serum creatinine levels not accurately reflect the GFR in patients with chronic renal failure?
25. What is the creatinine clearance a measurement of?
26. Why is the creatinine clearance a more reliable measurement of the GFR than serum creatinine levels? What is a disadvantage of creatinine clearance measurements?
27. What are some nonrenal causes of proteinuria?
28. What are the differences in site of action of thiazide, spironolactone, and loop and osmotic diuretics?
29. What are the differences in pharmacologic action between dopamine and fenoldopam?
30. What are the systemic changes that frequently accompany end-stage renal disease (ESRD)?
31. What are some anesthetic considerations for the anesthetic management of patients with ESRD?
32. Should succinylcholine be avoided in patients with ESRD?
33. What are some causes of prerenal oliguria?
34. What is the treatment for prerenal causes of oliguria?
35. What are some causes of oliguria due to intrinsic renal disease?
36. For oliguria that is secondary to renal causes such as acute tubular necrosis, is the urine typically concentrated or dilute? Does the urine typically contain excessive or minimal stores of sodium?
Liver and biliary tract disease
38. What are some physiologic functions of the liver?
39. What is the blood supply to the liver? What percent of the cardiac output goes to the liver?
40. What are some determinants of hepatic blood flow?
41. What is hepatic autoregulation? How is hepatic autoregulation affected by surgery and anesthesia?
42. What is the hepatic arterial buffer response? How is this hepatic response affected by anesthesia?
43. What results from sympathetic nervous stimulation of the liver?
44. How does positive pressure ventilation of the lungs affect hepatic blood flow?
45. How does congestive heart failure affect hepatic blood flow?
46. How do changes in cardiac output or myocardial contractility affect hepatic blood flow?
47. How do changes in arterial blood pressure affect hepatic blood flow?
48. How does the liver store glucose?
49. How does the liver maintain glucose homeostasis in times of starvation?
50. Why might patients with cirrhosis be more likely to develop hypoglycemia in the perioperative period?
51. What role does the liver play in blood coagulation? What is the clinical implication of this for the patient with liver disease?
52. How significant must liver dysfunction be before abnormal blood coagulation is noted? How can this be evaluated preoperatively?
53. What is the role of vitamin K in coagulation?
54. How does the liver facilitate the renal excretion of lipid soluble drugs?
55. How does chronic drug therapy affect the metabolism of anesthetic drugs by the liver?
56. How does chronic liver disease impact drug metabolism?
57. Why may hepatic drug metabolism be accelerated after the administration of certain medications?
58. What role does the liver play in the excretion of bilirubin? What is the clinical implication of this for the patient with liver disease?
59. What proteins are synthesized in the hepatocytes?
60. What is the role of the urea cycle in the hepatocytes?
61. What pathophysiologic changes are associated with end-stage liver disease (ESLD)?
62. What are the hemodynamic changes associated with ESLD?
63. What are some consequences of the portal hypertension seen in ESLD?
64. What are some of the symptoms of portal hypertension?
65. What are some complications that can occur as a result of the portal hypertension seen in ELSD?
66. What are some pulmonary complications that can be seen in ESLD?
67. What are some reasons why a patient with hepatic cirrhosis may have arterial hypoxemia? Does the administration of supplemental oxygen increase the oxygen saturation in these patients?
68. What are some causes of hepatic encephalopathy seen in patients with ESLD?
69. What is the therapy for hepatic encephalopathy? Is it effective?
70. What role does the liver play in drug binding to serum proteins? What is the clinical implication of this for the patient with liver disease?
71. Why is ascites thought to accumulate in patients with hepatic cirrhosis?
72. What are some complications associated with ascites?
73. What is the treatment for ascites?
74. How might renal function be affected in patients with hepatic cirrhosis?
75. What categories of hepatorenal syndrome have been described? Are there any therapies?
76. In the absence of surgical stimulation, how do regional and inhaled anesthetics affect hepatic blood flow?
77. Is there any evidence to suggest one inhaled anesthetic preserves hepatic autoregulation more than others?
78. What is halothane hepatitis? Are pediatric patients or adult patients more likely to develop halothane hepatitis?
79. What is the cause of halothane hepatitis?
80. How is the diagnosis of halothane hepatitis made?
81. Can volatile anesthetics, other than halothane, cause hepatotoxicity?
82. What are some commonly ordered liver function tests? What is the utility of liver function tests in the perioperative period?
83. What are some preoperative findings in patients with liver disease that are associated with increased postoperative morbidity?
84. What monitoring may be useful intraoperatively for patients with hepatic cirrhosis undergoing surgical procedures?
85. Why is the intraoperative maintenance of the arterial blood pressure particularly important in patients with hepatic cirrhosis?
86. When liver function tests become abnormal postoperatively, what is the most likely mechanism for the postoperative liver dysfunction? In what patients and types of surgeries are liver function tests most likely to become elevated postoperatively?
87. What are the most likely causes of postoperative liver dysfunction?
88. What laboratory values indicate an intrahepatic cause of liver dysfunction?
89. What are some causes of postoperative jaundice?
90. What is delirium tremens? How does it usually present?
91. What is the treatment of delirium tremens?
92. What is the mortality associated with delirium tremens? What is the usual cause of death in these patients?
93. What approximate percent of females and males aged 55 to 65 years are believed to have gallstones?
94. What is the potential problem with the use of opioids intraoperatively during a cholecystectomy or common bile duct exploration?
95. How can intraoperative spasm of the sphincter of Oddi be treated?
96. What are some anesthetic considerations for patients undergoing laparoscopic procedures?
Answers*
Renal disease
1. Essential physiologic functions of the kidneys include the excretion of metabolic wastes; the retention of nutrients; the regulation of water, tonicity, and electrolyte and hydrogen ion concentrations in the blood; and the production of hormones that contribute to water regulation and bone metabolism. (448)
2. Factors that place patients at an increased risk of acute renal failure in the perioperative period include advanced age, emergent surgery, liver disease, high-risk surgery, body mass index, peripheral vascular occlusive disease, and COPD. (449, Table 28-1)
3. Although the kidneys typically constitute only 0.5% of body weight, about 20% of the cardiac output normally goes to the kidneys. Of the 20%, more than two-thirds goes to the renal cortex and the remaining blood flow supplies the renal medulla. (448)
4. Renal blood flow and the GFR remain constant when mean arterial blood pressures range between 80 and 180 mm Hg. This autoregulatory function of the kidneys is accomplished by the afferent arteriolar vascular bed. The afferent arterioles are able to adjust their tone in response to changes in blood pressure, such that during times of higher mean arterial blood pressure the afferent arterioles vasoconstrict, whereas the opposite occurs during times of lower mean arterial blood pressure. This is important for two reasons. The ability of the kidneys to maintain constant renal blood flow despite fluctuations in blood pressure ensures continued renal tubular function in the face of changes, especially decreases, in blood pressure. In addition, autoregulatory responses of the afferent arterioles protect the glomerular capillaries from large increases in blood pressure during times of hypertension, as may occur with direct laryngoscopy. When mean arterial blood pressures are less than 80 mm Hg or greater than 180 mm Hg renal blood flow is blood pressure dependent. (448)
5. Even during normal kidney autoregulatory function, renal blood flow can be altered by sympathetic nervous system activity and by circulating renin. (448)
6. Renin is a proteolytic enzyme secreted by the juxtaglomerular apparatus of the kidney. There are at least three things that stimulate the release of renin from the endothelial cells of the afferent arteriole: (1) Sympathetic nervous stimulation; (2) decreased renal perfusion; and (3) decreased delivery of sodium to distal convoluted renal tubules. Renin increases efferent renal arterial arteriolar tone at low levels and causes afferent arteriolar constriction at higher levels. (449)
7. Renin is the rate-limiting enzyme in the production of angiotensin II. After its secretion from the juxtaglomerular apparatus of the kidneys, renin acts on angiotensinogen. Angiotensinogen is a large glycoprotein released by the liver to the circulation. After being cleaved by renin, angiotensin I is formed from angiotensinogen. Angiotensin I is in turn cleaved by angiotensin converting enzyme in the lungs to form angiotensin II. Angiotensin II stimulates the release of aldosterone from the adrenal cortex and is a potent vasoconstrictor. It also inhibits renin secretion as part of a negative feedback loop. (449)
Related posts:
Full access? Get Clinical Tree
