Practice questions answers Shock

Practice questions answers

Shock

© Jun Wang, MD, PhD

 

1. A. Presentations of fever and chills are suspicious of infection. In addition, this patient has lower abdominal pain with image studies showing extraluminal gas or feces, consistent with ruptured internal organ, most likely colon. The presence of tachypnea, tachycardia and skin cyanosis is highly suggestive for shock, further supported by persistent hypotension after adequate fluid resuscitation. In this case, this is most likely a septic shock, due to presentations of sepsis. Although diagnosis of sepsis is usually made empirically based on clinical presentations, especially evidence of organ dysfunctions, it is commonly required to have either positive blood culture results or clinical responses to antibiotics to confirm the diagnosis. Chest X-ray and echocardiography are used in diagnosis of obstructive shock. EKG can be used to diagnose cardiogenic shock. Flow cytometry can be used in diagnosis of lymphoid neoplasms and myeloid neoplasms, especially when there is leukocytosis. However, leukocytosis with left shift without blasts is less likely to be neoplastic. Urine sodium concentration will be reduced in hypovolemic shock. All these tests can be normal in septic shock.

 

2. D. A single factor deficiency is usually associated with prolonged PT or aPTT, but not both. Prolonged PT and aPTT at the same time can be caused by deficiency of common pathway factors, or deficiency of multiple factors. In addition, isolated factor deficiency will not cause abnormal platelet count. This patient has thrombocytopenia, and prolonged PT and aPTT, in a background of infection and hypotension. This is more consistent with disseminated intradil coagulation in a setting of septic shock. Abnormal results of these tests are caused by overactivation of coagulation components, and subsequent over consumption of coagulation factors and platelets. Coagulation factor inhibitors usually affect a specific factor, therefore result in prolonged PT or aPTT, but not both. Internal hemorrhage may cause acute anemia, but not necessarily cause disseminated intravascular coagulation. Platelet dysfunction will not cause abnormal PT or aPTT.

3. A. This is a case of septic shock, a type of distribution shock. Its hypotension is caused by abnormal dilation of vessels. Arrythmias and ventricular dysfunction are seen in cardiogenic shock. Although they might be seen in septic shock, there is no evidence for either in the current case. Internal hemorrhage may be associated with hypovolemic shock, but less likely in this patient, since the hemoglobin level is only mildly reduced. Even there is internal hemorrhage, the degree of hemorrhage is not sufficient to cause shock. Obstruction of major branches of aorta may be associated with obstructive shock.

4. A. The key pathogenetic factor in sepsis and septic shock is abnormal reaction to infections caused by cytokines and subsequent exaggerated inflammatory process and organ dysfunctions. Cardiac tumor involving conductive system is commonly seen in arrythmias, that may cause cardiogenic shock. Congenital vascular malformations usually presents at an early age, and does not commonly have fevers, etc. Primary immunodeficiency diseases are characterized by recurrent infections, usually starting at early age. Reduced cardiac output, although may be associated with hypotension in cardiogenic shock and obstructive shock, is not seen in septic shock. Indeed, cardiac output is commonly elevated in septic shock.

5. E. See discussion for question 1. Anaphylactic shock is characterized by a sudden onset of skin and/or mucosal urticarial changes, accompanied with wheezing and hypotension, and organ dysfunctions. Cardiogenic shock is caused by ventricular dysfunction, due to myocardial infarct, arrythmias, or mechanical abnormalities such as defects, etc. These patients should have presentations of associated disorders, such as chest pain, or previous history of palpitation, etc. Obstructive shock is caused by left ventricular underfilling resulted from reduced venous returns, or increased afterload, such as valve stenosis, etc. Besides features of shock, there are presentations of underlying disorders, such as pneumothorax, etc. Hypovolemic shock is caused by reduced circulating volume. These patients usually have history of fluid loss, either hemorrhage or diarrhea, etc. Fever and chills are not commonly seen in these settings. In addition, the skin tends to be warm in septic shock, but cool in others.

6. E. Presence of extraluminal gas or feces is highly suggestive of an internal organ rupture.  Anaphylactic shock is characterized by a sudden onset of skin and/or mucosal urticarial changes, accompanied with wheezing and hypotension, and organ dysfunctions. Congenital heart diseases usually are detected at an early age, and there are commonly abnormal heart sounds. Internal hemorrhage may be associated with hypovolemic shock, but less likely in this patient, since the hemoglobin level is only mildly reduced. Even there is internal hemorrhage, the degree of hemorrhage is not sufficient to cause shock. Primary immunodeficiency diseases are characterized by recurrent infections, usually starting at early age.

7. D. Shock is a condition of reduced tissue perfusion resulted in lactate acidosis and organ dysfunctions. Elevated plasma lactate is commonly seen in patients with shock. As a result, arterial oxygen and pH might be low in patients with shock. Factor VIII level is likely low, due to disseminated intravascular coagulation. Urine sodium concentration will be reduced in hypovolemic shock.

8. A. This patient has fever and chills, both suggestive of infection. With his additional presentations of hypotension, tachycardia, prolonged PT/PTT and thrombocytopenia, this is likely a septic shock with disseminated intravascular coagulation. The history of vomiting and neurological exam results of positive Kernig and Brudzinski signs are consistent with meningitis. What unique in this patient is his skin rash and petechia, both, in the background of meningitis and shock, are highly suggestive of Waterhouse-Friderichsen syndrome, as supported by his laboratory test results of hyponatremia and hypoglycemia. Since Waterhouse-Friderichsen syndrome is a result of adrenal insufficiency due adrenal hemorrhage, ACTH is elevated in these patients as a normal response from pituitary gland. Aldosterone and glucocorticoid are reduced due to adrenal insufficiency. Indeed, low levels of these two are causes of hyponatremia and hypoglycemia in patients with Waterhouse-Friderichsen syndrome. Fibrinogen is reduced due to disseminated intravascular coagulation. Insulin is increased in response to hyperglycemia, not hypoglycemia.

9. A. Abdominal CT would detect adrenal hemorrhage. Flow cytometry can be used in diagnosis of lymphoid neoplasms and myeloid neoplasms, especially when there is leukocytosis. Bone marrow biopsy can be used to determine marrow involvement of tumor or hematopoietic disorders, including anemia, lymphoid neoplasms and myeloid neoplasms. Echocardiography can be used to detect heart abnormalities, including cardiac tumor or tumor like growths, or ventricular dysfunctions that may be associated with cardiogenic shock and obstructive shock. Right heart catheterization can be used to measure right heart pressure and blood flow, that might be used to confirm pulmonary hypertension and assessing left heart conditions.

10. E. See discussion of question 8. Acute myeloid leukemia (AML) or acute lymphoblastic leukemia are characterized by circulating blasts. Insulinoma may present with hypoglycemia, but not abnormal coagulation tests and platelet counts. Pulmonary embolism may present with features of pulmonary hypertension, but not hypoglycemia. Vitamin K deficiency, including warfarin associated coagulopathy may present with bleeding symptoms and prolonged PT and/or PTT, but not thrombocytopenia or hypoglycemia. All these three usually do not have features of infection, nor hyponatremia.

11. E. Sudden onset of systemic symptoms of shortness of breath and hypotension after contact with an allergen, bug stung in this case, is consistent with an anaphylactic reaction.  Plasma tryptase is elevated after it is released from activated mast cells or basophils. Either positive blood culture results or clinical responses to antibiotics are used to confirm the diagnosis of sepsis, but have limited roles in other types of shock. Chest X-ray and echocardiography are used in diagnosis of obstructive shock. EKG can be used to diagnose cardiogenic shock. Urine sodium concentration will be reduced in hypovolemic shock.

12. A. Anaphylactic shock is cause by releasing of histamine, tryptase and other cytokines by activated basophils and mast cells. Broad spectrum antibiotics can be used for sepsis. Intravenous fluid is used for hypovolemic shock. Pericardial drainage is useful for obstructive shock caused by pericardial tamponade. Restoration of coronary circulation is used for coronary artery obstruction, that might cause cardiogenic shock.

13. A. See discussion of question 12. Bacterial endotoxin may cause various clinical presentations, including fever, chills, and diffuse endothelial damage that be associated with sepsis, septic shock and disseminated intravascular coagulation. Massive hemorrhage may cause hypovolemic shock. Pericardial tamponade may cause obstructive shock.

 

14. A. Sudden onset of systemic symptoms of shortness of breath and hypotension after contact with an allergen, bug stung in this case, is consistent with an anaphylactic shock. Cardiogenic shock is caused by ventricular dysfunction, due to myocardial infarct, arrythmias, or mechanical abnormalities such as defects, etc.  These patients should have presentations of associated disorders, such as chest pain, or previous history of palpitation, etc. Hypovolemic shock is caused by reduced circulating volume. These patients usually have history of fluid loss, either hemorrhage or diarrhea, etc. Tension pneumothorax is collection of air in the pleural cavity with mediastinal shifts. It may cause obstructive shock due to impaired left ventricular filling resulted from reduced venous returns. Typically it has physical examination findings of decreased or absent breath sounds on the ipsilateral site by auscultation, reduced tactile fremitus and hyper-resonant percussion sounds. Septic shock and sepsis have features of infection, such as fever, etc.  

 

15. C. This patient presents with chest discomfort, tachycardia, tachypnea and bilateral crackers and EKG findings of ST changes. These are consistent with myocardial ischemia and subsequent left heart dysfunction. Additional findings of hypotension and hypoxemia despite oxygen supplementation are consistent with shocks, specifically, cardiogenic shock, since ventricular dysfunction appears to be the cause of her presentations. It has been recommended to perform coronary angiography in patients with suspicious myocardial infarct and cardiogenic shock, not only for diagnosis, but for potential revascularization. Blood culture is useful in diagnosing septic shock and sepsis. Chest X-ray may help detecting pulmonary hypertension and pneumothorax, in cases of obstructive shock. Plasma tryptase is elevated in anaphylactic shock after it is released from activated mast cells or basophils. Urine sodium concentration will be reduced in hypovolemic shock.

 

16. B. Shock is a condition of reduced tissue perfusion resulted in lactate acidosis and organ dysfunctions. Elevated plasma lactate is commonly seen in patients with any types of shock. ACTH is elevated in patients with Waterhouse-Friderichsen syndrome as a result of adrenal insufficiency due adrenal hemorrhage, when serum potassium might be elevated. Leukocytosis can be seen in many types of infection, including sepsis and septic shock. Plasma histamine is elevated in anaphylactic shock after it is released from activated mast cells or basophils.

 

17. E. See discussion of question 15.  Abnormal dilation of vessels is seen in distribution shocks, including anaphylactic shock and septic shock. Hemorrhage and fluid loss are seen in hypovolemic shock. Large vessel thrombosis may cause obstructive shock due to reduced venous return and left ventricular underfilling.

 

18. B. See discussions of questions 5 and 14.

 

19. E. The presence of tachypnea, tachycardia, hypotension and skin cyanosis is highly suggestive for shock. The presence of bilateral lower extremity edema and sonographic findings of bilateral femoral veins are indicative an occlusion of inferior vena cava that may cause obstructive shock. Blood culture is useful in confirming sepsis and septic shock. However, even this patient has mild fever, infections that may cause sepsis and septic shock are not likely due to normal CBC. Coronary angiography and cardiac enzyme tests can be used to detect myocardial ischemia/injury, that may cause cardiogenic shock. However, it is unlikely in this case due to unremarkable EKG findings. Urine sodium concentration will be reduced in hypovolemic shock. It is not likely to be useful in this patient due to lack of relevant history.

 

20. D. Large vessel thrombosis may cause obstructive shock due to reduced venous return and left ventricular underfilling. Abnormal dilation of vessels is seen in distribution shocks, including anaphylactic shock and septic shock. Hemorrhage and fluid loss are seen in hypovolemic shock. Increased afterload may cause obstructive shock. However, there is no evidence of pulmonary hypertension or valvular stenosis or aortic dissection in this patient. Arrythmias and ventricular dysfunction are seen in cardiogenic shock.

 

21. E. Shock is a condition of reduced tissue perfusion resulted in lactate acidosis and organ dysfunctions. This patient does have a long history of type 2 diabetes. However, diabetic nephropathy is a result of long standing hyperglycemia, a condition that is less likely in this patient with normal blood glucose, HbA1c and lipid profile. There is no evidence of GI-bleeding, glomerulonephritis, and high-protein diet for this patient.

 

22. D. Obstructive shock is cause by impaired left ventricular filling resulted from reduced venous returns, or increased afterload due to valvular stenosis or aortic dissection. See discussion of questions 1 and 5.

 

23. E. The presence of tachycardia and hypotension in a background of upper GI bleeding is highly suggestive for hypovolemic shock due to bleeding. He has a long history of hepatitis. Laboratory tests reveal severe anemia and abnormal liver functions, suggestive a portal hypertension and subsequent esophageal varices. Upper GI tract endoscopy not only can confirm the diagnosis, but can treat the bleeding lesion as well. See discussion of question 15 as well.

 

24. C. Hypovolemic shock is caused by reduced circulating volume. These patients usually have history of fluid loss, either hemorrhage or diarrhea, etc. Abnormal dilation of vessels is seen in distribution shocks, including anaphylactic shock and septic shock. Left ventricular underfilling resulted from reduced venous returns, or increased afterload, such as valve stenosis, etc are seen in obstructive shock. Arrythmias and ventricular dysfunction are seen in cardiogenic shock.

 

25. C. Urine sodium concentration will be reduced in hypovolemic shock. Elevated cardiac enzymes are seen commonly in myocardial injury, that might be associated with cardiogenic shock. Increased absolute eosinophilic count may be associated with allergic reaction, including anaphylactic shock. Pericardial tamponade may cause obstructive shock. Positive blood culture may be seen in sepsis and septic shock.

 

26. C. See discussion of questions 1 and 5.

 

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