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PA5.1-6 | Hemodynamic Disorders — PBL Case

CLINICAL SETTING

Vijaya, a 34-year-old agricultural labourer from a village in Andhra Pradesh, arrives at the primary health centre by autorickshaw, unconscious. Her family reports a 3-year history of progressively worsening abdominal swelling and yellow discolouration of the eyes. Two hours ago she vomited approximately 1.5 litres of bright red blood in two episodes, turned cold and clammy, and lost consciousness. On examination at the PHC: BP 70/40 mmHg, pulse 136/min (thin and thready), respiratory rate 28/min, temperature 36.1 °C. The skin is cold and pale. Abdomen is grossly distended with a fluid thrill. The sclera and skin are deeply icteric. The PHC doctor notes multiple spider naevi on her chest and a caput medusae around the umbilicus. Blood glucose is 52 mg/dL. He phones the district hospital's medicine registrar for advice. She is transferred urgently by ambulance.

Trigger 1: The Cold, Clammy Patient

At the district hospital, Vijaya's BP is now 60/30 mmHg with a pulse of 148/min. Two large-bore IV lines are inserted and crystalloid resuscitation begun. ABG shows: pH 7.22, lactate 6.8 mmol/L, BE −10 mEq/L. Blood is sent urgently. Results: Hb 5.4 g/dL, WBC 12,000/µL, platelets 88,000/µL, PT 22 sec (INR 2.4), APTT 52 sec, albumin 1.9 g/dL, total bilirubin 8.2 mg/dL, ALT 88 U/L, AST 142 U/L. Upper GI endoscopy reveals large bleeding oesophageal varices. The registrar explains to the intern: Vijaya is in shock, but this is NOT the same shock as septic shock or cardiogenic shock. The intern asks: what kind of shock is this, and what does the cold periphery, lactate, and BP tell us about what is happening to Vijaya's cells right now?

DISCUSSION POINTS

Vijaya has BP 60/30 mmHg, cold periphery, lactate 6.8 mmol/L, and Hb 5.4 g/dL. Classify the type of shock, describe its pathogenesis, and explain the three stages of shock progression — which stage is Vijaya in, and what evidence supports your answer?
The body responds to haemorrhagic shock through multiple compensatory mechanisms. Describe the neuroendocrine response (baroreceptor reflex, catecholamine release, RAAS activation, ADH) and how each maintains perfusion to vital organs at the expense of peripheral tissue.
Serum lactate is 6.8 mmol/L. Why does lactic acidosis develop in shock, and what does the metabolic acidosis (pH 7.22, BE −10) tell you about the adequacy of tissue oxygenation at the cellular level?
Vijaya has petechiae on her gums and oozing from IV insertion sites in addition to the variceal bleed. Her platelets are 88,000/µL, PT elevated, and INR 2.4. Name the types of haemorrhage visible and explain how liver failure simultaneously causes coagulopathy through two distinct mechanisms.

Click to reveal Trigger 2: Why Is Her Abdomen Full of Fluid? (discuss previous trigger first!)

Trigger 2: Why Is Her Abdomen Full of Fluid?

Vijaya is stabilised with blood transfusions, terlipressin, and endoscopic banding of the varices. The intern now has time to examine her more carefully. Diagnostic paracentesis yields straw-coloured fluid: protein 12 g/L, LDH 80 U/L (SAAG calculated as 14 g/L). Ultrasound-Doppler confirms portal hypertension with hepatofugal flow. The medical student asks: if the varices bled because of high portal pressure, why is the abdomen full of LOW-protein fluid rather than blood or high-protein exudate? The registrar explains that Vijaya's fluid accumulation has at least THREE different mechanisms operating simultaneously. A liver biopsy taken at the same admission shows: nodules of hepatocytes separated by fibrous bands with absent normal architecture; the sinusoids around the central veins are markedly dilated and engorged with red blood cells; periportal hepatocytes are pale but viable while centrilobular hepatocytes are necrotic.

DISCUSSION POINTS

The peritoneal fluid has protein 12 g/L and SAAG 14 g/L. Using Starling forces and the definition of transudate vs exudate, classify this fluid and explain why portal hypertension raises hydrostatic pressure in the splanchnic capillaries to produce low-protein ascites.
Vijaya has three simultaneous mechanisms driving her fluid accumulation: (1) portal hypertension → raised splanchnic hydrostatic pressure, (2) hypoalbuminaemia (albumin 1.9 g/dL) → reduced plasma oncotic pressure, and (3) secondary hyperaldosteronism → sodium and water retention. Explain each mechanism using Starling forces and link each to Vijaya's specific lab findings.
The liver biopsy shows engorged, dilated sinusoids around the central veins with centrilobular necrosis and viable periportal hepatocytes. What is the name of this pattern, which chamber of the heart failing produces it, why is the centrilobular zone affected first, and what is the gross appearance of this pattern?
The medical student notes that Vijaya has both active oesophageal haemorrhage (frank blood loss) and diffuse petechial haemorrhage from coagulopathy. Classify each type of haemorrhage by location, size, and mechanism, and explain the clinical significance of each — why does the site of haemorrhage matter as much as the volume?

Click to reveal Trigger 3: The Clot That Should Not Have Formed (discuss previous trigger first!)

Trigger 3: The Clot That Should Not Have Formed

One week after stabilisation, Vijaya develops sudden severe right upper quadrant pain. Doppler ultrasound shows thrombosis of the right portal vein branch. The hepatologist explains to the intern that portal vein thrombosis (PVT) is a recognised complication of cirrhosis, driven by stasis of portal blood flow and a paradoxical pro-thrombotic state despite the prolonged PT. He requests a hypercoagulability workup: results show elevated Factor VIII, reduced protein C, and reduced antithrombin III. Plain X-ray of the abdomen to investigate pain shows no free air. A CT confirms right lobe hepatic infarction — a rare event because the liver has a dual blood supply, but possible when both branches are compromised. The radiologist notes the infarcted segment is pale and wedge-shaped. The intern now needs to synthesise: how can a patient with a coagulopathy (prolonged PT) simultaneously develop a thrombus?

DISCUSSION POINTS

Vijaya has prolonged PT/INR yet develops portal vein thrombosis. Explain this paradox using the concept of Virchow's triad — which of the three components is dominant in portal vein thrombosis in cirrhosis, and why does reduced protein C and antithrombin III shift the balance toward thrombosis despite low clotting factors?
The CT shows a pale, wedge-shaped hepatic infarct in the right lobe. Classify this infarct as red or pale, explain why the liver (which has a dual blood supply) can undergo infarction when both supply routes are compromised, and describe the expected histological appearance at 3 days, 1 week, and 4 weeks.
Distinguish between arterial and venous thrombi in terms of: composition (platelet-fibrin vs red cell-rich), gross appearance, lines of Zahn (present or absent), Virchow's triad component dominant, and the expected fate (embolism vs organisation and recanalisation). Explain which type Vijaya's portal vein thrombus most closely resembles.
Construct a unified narrative of Vijaya's entire haemodynamic case: starting from cirrhosis-induced portal hypertension, trace the sequence through congestion (nutmeg liver), oedema/ascites formation (three mechanisms), variceal haemorrhage and hypovolaemic shock, compensatory responses, and finally portal vein thrombosis and hepatic infarction — identifying the dominant hemodynamic disorder at each stage.

Group Task Assignments

Group 1: Oedema mechanisms and fluid classification

Using Vijaya's case, construct a Starling forces diagram for her splanchnic capillary bed showing: normal forces vs forces in portal hypertension + hypoalbuminaemia. Calculate the direction of net fluid flux at each stage and explain why lymphatic drainage eventually fails to compensate, producing ascites.
Prepare a comparison table of transudate vs exudate covering: mechanism, protein content, LDH, SAAG (for ascites), specific gravity, and two clinical examples for each. Classify Vijaya's ascitic fluid using all four criteria.

Competencies: PA5.1, PA5.2

Group 2: Congestion, haemorrhage, and their morphological signatures

Describe the gross and microscopic appearances of chronic venous congestion in the liver (nutmeg liver): normal architecture vs congestive changes — central vein dilation, sinusoidal engorgement, centrilobular necrosis, and periportal fatty change. Draw a cross-section of a hepatic lobule and annotate the zones of injury.
Classify all the haemorrhagic events in Vijaya's case by type: petechiae (gums, IV sites), purpura, haematemesis (variceal). For each, specify the size, mechanism, and whether it indicates a platelet defect, coagulation defect, or direct vascular injury.

Competencies: PA5.2

Group 3: Shock — types, stages, and cellular consequences

Compare the four types of shock (hypovolaemic, cardiogenic, distributive/septic, obstructive) using a table: haemodynamic profile (CO, SVR, CVP), skin findings, mechanism, and one clinical example for each. Identify which type Vijaya presents with and explain the overlap with distributive physiology in end-stage liver disease.
Trace the three stages of shock in Vijaya's case using her vital signs, lactate, and clinical findings: (1) non-progressive — what compensatory mechanisms were operating before she lost consciousness? (2) progressive — what is happening at the cellular level now? (3) irreversible — what end-organ changes would you expect if resuscitation fails?

Competencies: PA5.3

Group 4: Thrombosis, embolism, and infarction

Explain Virchow's triad in portal vein thrombosis in cirrhosis: for each component (endothelial injury, stasis/turbulence, hypercoagulability) describe the specific mechanism in Vijaya's case, citing her lab results (protein C, antithrombin III, elevated Factor VIII, portal blood stasis from fibrosis).
Describe the morphological evolution of a hepatic infarct at three time points: (a) 6 hours — what is the earliest change visible on H&E? (b) 72 hours — describe ghost cell outline, nuclear changes, and inflammatory response. (c) 4 weeks — what replaces the necrotic tissue, and can this tissue regenerate or must it scar?

Competencies: PA5.4, PA5.5, PA5.6

Group 5: Clinico-pathological synthesis and the pathologist's role

Write a mock histopathology report for Vijaya's liver biopsy: describe the low-power architecture (nodule formation, fibrosis, loss of normal lobular pattern), the mid-power sinusoidal congestion and centrilobular necrosis, and the high-power hepatocyte changes. Provide a final diagnosis and clinical comment linking pathological findings to portal hypertension.
Research and present the concept of the 'infarct-resistant' liver: why does the liver rarely infarct despite being subjected to extreme portal hypertension and shock? Under what specific circumstances can hepatic infarction occur? Use Vijaya's portal vein thrombosis to illustrate the exception.

Competencies: PA5.1, PA5.6

Learning Issues

Research these questions and bring your findings to the discussion.

[PA5.1] What are the five mechanisms of oedema, and which specific mechanism(s) are operating in Vijaya's ascites? How does Starling's law explain why each mechanism produces fluid accumulation, and what distinguishes a transudate from an exudate?
[PA5.2] What is the difference between hyperaemia and congestion? What is chronic venous congestion of the liver (nutmeg liver) — describe the gross and microscopic appearance and explain why centrilobular hepatocytes die first while periportal hepatocytes survive.
[PA5.3] Define shock and classify its four types. What are the three stages of shock? Which type is Vijaya in, and what do the lactate level, cold periphery, and metabolic acidosis tell you about tissue-level oxygen delivery?
[PA5.4] What is Virchow's triad? How does cirrhosis simultaneously create conditions for all three components of the triad to produce portal vein thrombosis despite a prolonged PT? What are the four possible fates of a thrombus?
[PA5.5] Define infarction. Why is the liver's infarct usually rare despite high portal pressure? What conditions led to Vijaya's hepatic infarction, and how does the dual blood supply normally protect against it?
[PA5.6] Describe the gross and microscopic features of the hepatic infarct at 6 hours, 72 hours, and 4 weeks. What type of necrosis occurs in hepatic infarction — is it coagulative or liquefactive, and why?