Porth's Essentials of Pathophysiology, 4e

510

Circulatory Function

U N I T 5

A. Use information regarding the compensatory mechanisms in circulatory shock to explain this man’s presenting symptoms, including urinary output. B. Use Figure 20-8 to hypothesize about this man’s blood loss and maintenance of blood pressure. C. The treatment of hypovolemic shock is usually directed at maintaining the circulatory volume through fluid resuscitation rather than maintaining the blood pressure through the use of vasoactive medications. Explain. R E F E R E N C E S 1. Yancy CW, Jessup M, Bozkurt B, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation . 2013;128(16):e240–e327. 2. Arnold JMO, Liu P, Demers C, et al. Canadian Cardiovascular Society consensus conference recommendations on heart failure 2006: diagnosis and management. Can J Cardiol. 2006;22:23–45. 3. Bibbins-Domingo K, Pletcher MJ, Lin F, et al. Racial differences in incident heart failure among young adults. N Engl J Med. 2009;360(12):1179–1190. 4. Mozaffarian D, Anker SD, Anand I, et al. Prediction of mode of death in heart failure: the seattle heart failure model. Circulation. 2007;116(4):392–398. 5. Opie LH, Hassenfuss G. Mechanisms of cardiac contraction and relaxation. In: Bonow R, Mann DL, Zipes DP, et al., eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine . 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:459–486. 6. Guyton AC, Hall JE. Textbook of Medical Physiology . 11th ed. Philadelphia, PA: Elsevier Saunders; 2011:106, 255–254, 273–282. 7. Vuckovic KM, Fink AM. The 6-min walk test: is it an effective method for evaluating heart failure therapies? Biol Res Nurs. 2012;14(2):147–159. 8. Klabunde RE. Cardiovascular Physiology Concepts . Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams & Wilkins; 2011. 9. Piano MR, Bondmass M, Schwertz DW. The molecular and cellular pathophysiology of heart failure. Heart Lung. 1998;27(1):3–19. 10. Mann DL. Pathophysiology of heart failure. In: Bonow R, Mann DL, Zipes DP, et al., eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine . 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:487–504. 11. Piano MR, Law WR. Cardiovascular physiology: the myocardium. In: Moser DK, Riegel B, eds. Cardiac Nursing: A Companion to Braunwald’s Heart Disease . Philadelphia, PA: Elsevier Saunders; 2007. 12. Thomas GD. Neural control of the circulation. Adv Physiol Educ. 2011;35(1):28–32. 13. Ronco C, Kaushik M, Valle R, et al. Diagnosis and management of fluid overload in heart failure and cardio-renal syndrome: the “5B” approach. Semin Nephrol. 2012;32(1):129–141. 14. Levin ER, Gardner DG, Samson WK. Natriuretic peptides. N Engl J Med. 1998;339:321–328. 15. Spieker LE, Lüscher TF. Will endothelin receptor antagonists have a role in heart failure? Med Clin N Am. 2003;87:459–474.

SUMMARY CONCEPTS (continued)

respiratory distress syndrome (ALI/ARDS) is characterized by changes in the permeability of the alveolar–capillary membrane with development of interstitial edema and severe hypoxemia that is refractory to oxygen therapy.The renal tubules are particularly vulnerable to ischemia, and acute kidney injury is an important complication of shock. Gastrointestinal ischemia may lead to gastrointestinal bleeding and increased vascular permeability to intestinal bacteria, which can cause further sepsis and shock. Disseminated intravascular coagulation (DIC) is characterized by formation of small clots in the circulation. Multiple organ dysfunction syndrome (MODS), perhaps the most ominous complication of shock, rapidly depletes the body’s ability to compensate and ultimately recover from the shock state. 1. A 75-year-old woman with long-standing hypertension and angina due to coronary heart disease presents with ankle edema, nocturia, increased shortness of breath with activity, and a chronic nonproductive cough. Her blood pressure is 170/80 and her heart rate 92. Electrocardiography and chest radiography indicate the presence of left ventricular hypertrophy. A. Relate the presence of uncontrolled hypertension and coronary artery disease to the development of heart failure in this woman. B. Explain the significance of left ventricular hypertrophy in terms of both a compensatory mechanism and a pathologic mechanism in the progression of heart failure. C. Use Figure 20-2 to explain this woman’s symptoms, including shortness of breath and nonproductive cough. 2. A 26-year-old man is admitted to the emergency department after an automobile injury with excessive blood loss. He is alert and anxious, his skin is cool and moist, his heart rate is 135, and his blood pressure is 100/85. He is receiving intravenous fluids, which were started at the scene of the accident by an emergency medical technician. He has been typed and cross-matched for blood transfusions and a urinary catheter has been inserted to monitor his urinary output. His urinary output has been less than 10 mL since admission and his blood pressure has dropped to 85/70. Efforts to control his bleeding have been unsuccessful and he is being prepared for emergency surgery. R E V I EW E X E R C I S E S