# Clinical Cases: Surgical Critical Care

## Case 1: Septic Shock from Anastomotic Leak

### Clinical Image
![CT scan showing post-operative anastomotic leak with abscess](case_01_image.jpg)
*Source: [Wikimedia Commons - Abdominal CT](https://commons.wikimedia.org/wiki/Category:CT_scans_of_the_abdomen) - CC BY-SA 4.0*

### Case Presentation
A 68-year-old man is post-operative day 5 from a low anterior resection for rectal cancer. He initially did well but now presents with fever to 39.2 degrees Celsius, heart rate 118 bpm, blood pressure 85/50 mmHg (previously 130/75 mmHg), and diffuse abdominal tenderness. Labs show WBC 18,000, lactate 4.8 mmol/L, and creatinine rising from 1.0 to 2.1 mg/dL. The sub-intern recognizes septic shock and initiates the sepsis bundle: blood cultures are obtained, broad-spectrum antibiotics (piperacillin-tazobactam and vancomycin) are administered within 30 minutes, and crystalloid resuscitation (30 mL/kg) is started. Despite 3 liters of fluid, blood pressure remains 80/45 mmHg. Norepinephrine is initiated through a peripheral IV while central access is obtained, rapidly titrated to achieve MAP greater than 65 mmHg. CT abdomen/pelvis with oral and IV contrast reveals free air, fluid collection at the anastomosis, and stranding consistent with anastomotic leak. The attending surgeon is notified for emergent source control. The patient is taken to the OR where a leaking anastomosis is taken down, an end colostomy is created, and the abdomen is copiously irrigated. Post-operatively, he requires 48 hours of vasopressor support and mechanical ventilation. Antibiotics are de-escalated to meropenem based on culture results (Escherichia coli and Bacteroides fragilis). He is extubated on POD 3 from re-exploration and discharged on POD 12.

### Key Learning Points
- The one-hour sepsis bundle: measure lactate, obtain blood cultures, administer broad-spectrum antibiotics, give 30 mL/kg crystalloid for hypotension or lactate greater than 4, and start vasopressors if hypotension persists despite fluids
- Source control is critical in surgical sepsis; antibiotics alone cannot treat anastomotic leak, abscess, or necrotic tissue - the source must be addressed
- Anastomotic leak typically presents POD 3-7 with fever, tachycardia, abdominal pain, and signs of peritonitis; maintain high suspicion in post-colorectal surgery patients
- Norepinephrine is first-line vasopressor for septic shock, targeting MAP greater than 65 mmHg; peripheral vasopressors can be used temporarily while central access is obtained

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## Case 2: ARDS Management After Aspiration

### Clinical Image
![Chest X-ray showing bilateral infiltrates consistent with ARDS](case_02_image.jpg)
*Source: [Wikimedia Commons - ARDS Chest X-ray](https://commons.wikimedia.org/wiki/Category:Acute_respiratory_distress_syndrome) - CC BY-SA 3.0*

### Case Presentation
A 55-year-old woman undergoes emergent laparotomy for small bowel obstruction. Post-extubation in the PACU, she vomits and aspirates gastric contents. She develops progressive hypoxemia over the next 12 hours, requiring re-intubation. CXR shows bilateral diffuse infiltrates. Her P/F ratio (PaO2/FiO2) is 85 on FiO2 1.0 and PEEP 10, meeting Berlin criteria for severe ARDS. The surgical ICU team implements lung-protective ventilation: tidal volume is set at 6 mL/kg of ideal body weight (IBW 60 kg, so Vt = 360 mL), respiratory rate 22 to maintain minute ventilation, and PEEP titrated up to 16 cm H2O per the ARDSNet PEEP/FiO2 table. Plateau pressure is monitored and kept below 30 cm H2O. Despite optimization, her P/F ratio remains less than 100. The team initiates prone positioning: she is positioned prone for 16 hours, then supine for 8 hours, cycling daily. Within 2 days of prone positioning, her P/F ratio improves to 150. Neuromuscular blockade with cisatracurium is used for the first 48 hours to improve ventilator synchrony and reduce oxygen consumption. Conservative fluid management targets even to slightly negative fluid balance after initial resuscitation to reduce pulmonary edema. By day 7, she is back supine full-time with improving oxygenation. She is extubated on day 10 and discharged from ICU on day 14.

### Key Learning Points
- Berlin criteria for ARDS: acute onset (within 1 week), bilateral opacities on imaging, not fully explained by cardiac failure/fluid overload, P/F ratio determines severity (mild 200-300, moderate 100-200, severe less than 100)
- Lung-protective ventilation is the cornerstone: low tidal volume (6 mL/kg IBW), plateau pressure less than 30 cm H2O, higher PEEP, permissive hypercapnia (accept pH greater than 7.20)
- Prone positioning for 12-16 hours/day in severe ARDS (P/F less than 150) reduces mortality by improving V/Q matching and recruiting dependent lung
- Conservative fluid management after initial resuscitation improves oxygenation without compromising outcomes

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## Case 3: Weaning from Mechanical Ventilation

### Clinical Image
![ICU patient during spontaneous breathing trial for ventilator weaning](case_03_image.jpg)
*Source: [Wikimedia Commons - Mechanical Ventilation](https://commons.wikimedia.org/wiki/Category:Mechanical_ventilation) - CC BY-SA 4.0*

### Case Presentation
A 62-year-old man has been mechanically ventilated for 6 days following a complicated Whipple procedure with post-operative bleeding requiring re-exploration. He has been off vasopressors for 48 hours and is on FiO2 35%, PEEP 5, with adequate oxygenation (SpO2 97%). Sedation has been weaned, and he is alert, following commands, and has a strong cough. The team performs daily screening for spontaneous breathing trial (SBT) readiness: adequate oxygenation (FiO2 less than 50%, PEEP less than or equal to 8) - yes; hemodynamically stable without vasopressors - yes; alert and following commands - yes; adequate cough and manageable secretions - yes. He meets criteria for SBT. The respiratory therapist places him on pressure support of 5 cm H2O and CPAP 5 (minimal support) for a 30-minute trial. He tolerates this well: respiratory rate 18 (less than 35), tidal volume adequate, no accessory muscle use, oxygen saturation stable at 96%, heart rate and blood pressure stable, no distress. He passes the SBT. Before extubation, the team assesses for cuff leak (present, suggesting low risk of post-extubation stridor), confirms he can protect his airway, and ensures reintubation supplies are at bedside. He is extubated successfully. Supplemental oxygen via nasal cannula is provided. He is monitored closely for 24 hours and does well without reintubation.

### Key Learning Points
- Daily screening for SBT readiness: adequate oxygenation on low FiO2/PEEP, hemodynamic stability, adequate mental status, and manageable secretions
- Spontaneous breathing trial methods: T-piece (no support), low-level pressure support (5-8 cm H2O), or CPAP; 30-120 minute duration
- SBT success criteria: respiratory rate less than 35, stable vital signs, no distress, adequate tidal volume, stable oxygenation
- Coordinating spontaneous awakening trials (SAT) with SBT improves weaning outcomes; assess sedation needs before SBT