# Clinical Cases: Shock and Vasopressor Management

## Case 1: Septic Shock - Vasopressor Escalation

### Clinical Image
![Chest X-ray showing bilateral pneumonia with consolidation](case_01_image.jpg)
*Source: [Wikimedia Commons - Pneumonia X-ray](https://commons.wikimedia.org/wiki/File:X-ray_of_lobar_pneumonia.jpg) - CC BY-SA 4.0*

### Case Presentation
A 72-year-old man with diabetes mellitus and chronic kidney disease presents with confusion, productive cough, and fever for 2 days. On arrival, vital signs show temperature 39.5C (103.1F), heart rate 125 bpm, respiratory rate 28/min, blood pressure 78/42 mmHg (MAP 54), and SpO2 88% on room air. He is started on supplemental oxygen and the sepsis bundle is initiated. Blood cultures and sputum cultures are obtained, and broad-spectrum antibiotics (ceftriaxone and azithromycin) are administered within 45 minutes. Lactate returns at 6.8 mmol/L. A 30 mL/kg crystalloid bolus (2.1L for 70 kg patient) is administered over 30 minutes. Post-fluid resuscitation, MAP increases to 58 mmHg but remains below target. A central venous catheter is placed in the right internal jugular vein, and norepinephrine is initiated at 0.1 mcg/kg/min. Norepinephrine is titrated to 0.3 mcg/kg/min over 2 hours, achieving MAP of 68 mmHg. Repeat lactate at 4 hours is 4.2 mmol/L, showing 38% clearance. By 12 hours, norepinephrine requirements increase to 0.5 mcg/kg/min despite adequate volume status (IVC greater than 2 cm with less than 50% collapsibility on bedside ultrasound). Vasopressin 0.03 units/min is added as a second agent. Hydrocortisone 50 mg IV every 6 hours is initiated for refractory shock requiring multiple vasopressors. Over the next 48 hours, with source control (aspiration pneumonia, treated with antibiotics), vasopressors are gradually weaned, and he is transferred out of the ICU on day 5.

### Key Learning Points
- Norepinephrine is the first-line vasopressor for septic shock due to its potent alpha-1 vasoconstriction with modest beta-1 inotropy
- Vasopressin (0.03-0.04 units/min fixed dose) is added as a second-line agent when norepinephrine requirements exceed 0.25-0.5 mcg/kg/min to reduce catecholamine exposure
- Corticosteroids (hydrocortisone 200 mg/day) are indicated for septic shock refractory to fluids and requiring moderate-to-high dose vasopressors; they accelerate shock reversal
- Lactate clearance of greater than 10-20% every 2 hours indicates adequate resuscitation response; failure to clear suggests ongoing hypoperfusion or cellular dysfunction

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## Case 2: Obstructive Shock - Massive Pulmonary Embolism

### Clinical Image
![Pulmonary embolism imaging showing perfusion defects](case_02_image.jpg)
*Source: [Wikimedia Commons - Pulmonary Embolism](https://commons.wikimedia.org/wiki/Category:Pulmonary_embolism) - CC BY-SA 3.0*

### Case Presentation
A 58-year-old woman presents to the emergency department with sudden-onset severe dyspnea, chest pain, and near-syncope. She had an arthroscopic knee surgery 10 days ago and has been relatively immobile since. On examination, vital signs show heart rate 128 bpm, respiratory rate 32/min, blood pressure 76/50 mmHg (MAP 59), and SpO2 82% on 15L non-rebreather. She appears pale, diaphoretic, and in respiratory distress. JVP is markedly elevated. Cardiac examination reveals a loud P2 and right ventricular heave. Bedside echocardiography shows severe right ventricular dilation and dysfunction with a "D-shaped" septum indicating interventricular septal bowing into the left ventricle from RV pressure overload. ECG shows sinus tachycardia, S1Q3T3 pattern, and right heart strain pattern. Given the high clinical suspicion for massive PE with hemodynamic instability, she is immediately given IV unfractionated heparin bolus. However, her blood pressure continues to decline to 68/42 mmHg despite 1L fluid bolus, and norepinephrine is initiated. The team recognizes that supportive measures alone are unlikely to reverse the RV failure. Given the hemodynamic instability, contraindications to thrombolysis are reviewed (none present), and systemic alteplase (tPA) 100 mg IV is administered over 2 hours. Within 90 minutes of thrombolysis initiation, her blood pressure improves to 98/64 mmHg, and norepinephrine is weaned. CT pulmonary angiogram (obtained after stabilization) confirms large bilateral pulmonary emboli with right heart strain. She is transitioned to therapeutic anticoagulation and discharged on apixaban with plan for hypercoagulability workup.

### Key Learning Points
- Obstructive shock from massive PE presents with sudden hypotension, elevated JVP, and right heart failure signs; bedside echo showing RV dilation is highly suggestive
- Massive PE with hemodynamic instability is an indication for systemic thrombolysis (tPA 100 mg over 2 hours) despite bleeding risks, as the alternative is death from RV failure
- In obstructive shock, fluid administration should be judicious - excessive fluids can worsen RV function by increasing wall tension; small boluses (250-500 mL) are appropriate
- The hemodynamic profile of obstructive shock shows elevated CVP, low cardiac output, and elevated SVR (similar to cardiogenic shock), distinguished by the acute obstruction to flow

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## Case 3: Cardiogenic Shock - Acute MI with Pump Failure

### Clinical Image
![Diagram showing cardiogenic shock pathophysiology](case_03_image.jpg)
*Source: [Wikimedia Commons - Cardiogenic Shock](https://commons.wikimedia.org/wiki/File:Blausen_0175_Cardiogenic_Shock.png) - CC BY 3.0*

### Case Presentation
A 65-year-old man with hypertension and hyperlipidemia presents with 4 hours of crushing substernal chest pain radiating to his left arm, associated with diaphoresis and nausea. On arrival, vital signs show heart rate 105 bpm, respiratory rate 26/min, blood pressure 88/62 mmHg (MAP 71), and SpO2 92% on room air. ECG shows ST-segment elevation in leads V1-V4 consistent with anterior STEMI. Troponin I is markedly elevated at 15.2 ng/mL. Physical examination reveals cool, mottled extremities, JVP elevated at 12 cm, bibasilar crackles on lung auscultation, and a new S3 gallop. Bedside echocardiography shows severely reduced left ventricular ejection fraction (estimated 20%) with akinesis of the anterior wall and septum. Lactate is 4.8 mmol/L. He is diagnosed with cardiogenic shock secondary to acute anterior STEMI. The STEMI activation is called, and he is taken emergently for cardiac catheterization. Given his hypotension, a small fluid bolus (250 mL) is given cautiously, and dobutamine is initiated at 5 mcg/kg/min for inotropic support. As blood pressure continues to decline, norepinephrine 0.1 mcg/kg/min is added for vasoconstriction. In the cath lab, a complete occlusion of the proximal LAD is found and successfully stented. Post-PCI, an intra-aortic balloon pump (IABP) is placed for additional hemodynamic support. Over the next 72 hours, his ejection fraction improves to 35%, and inotropes and IABP are weaned. He is started on guideline-directed medical therapy for heart failure.

### Key Learning Points
- Cardiogenic shock presents with signs of congestion (elevated JVP, pulmonary edema) AND hypoperfusion (cool extremities, altered mentation, oliguria, elevated lactate)
- The hemodynamic profile shows elevated CVP/PCWP, low cardiac output, and elevated SVR (heart is failing despite high filling pressures)
- Management of cardiogenic shock from acute MI prioritizes emergent revascularization (PCI within 90 minutes); delays in reperfusion worsen outcomes
- Inotropes (dobutamine) augment cardiac contractility; vasopressors (norepinephrine) may be needed for severe hypotension; mechanical support (IABP, Impella, ECMO) provides a bridge to recovery or definitive therapy