Acute Pancreatitis & Mesenteric Ischemia
Comprehensive emergency protocol for life-threatening acute pancreatitis and acute mesenteric ischemia (AMI). Covers the revised Atlanta criteria and BISAP scoring, goal-directed balanced crystalloid hydration vs. fluid overload prevention, acute mesenteric ischemia arterial embolism vs. thrombosis, early CTA diagnostics, and urgent vascular surgical revascularization.
Resuscitation Quick Ribbon (First 2 Minutes)
Bottom-Line Clinical Pearl
Acute mesenteric ischemia classically presents with severe, unremitting abdominal pain out of proportion to physical exam findings. A normal serum lactate level DOES NOT exclude early mesenteric ischemia; lactate only rises after full-thickness bowel infarction and necrosis have occurred.
The Bedside Index for Severity in Acute Pancreatitis (BISAP) calculated within 24 hours predicts in-hospital mortality (1 point for each present):
| BISAP Criterion | Definition & Threshold | Mortality Prediction |
|---|---|---|
| B - BUN | BUN > 25 mg/dL (8.9 mmol/L) | Score 0 - 2: Low mortality (< 1 - 2%); candidate for floor admission. |
| I - Impaired Mental Status | Glasgow Coma Scale < 15 or disorientation | Score 3 - 5: High mortality (5 - 20%); early progressive organ failure risk; mandates ICU admission. |
| S - SIRS | Presence of >= 2 SIRS criteria (Temp, HR > 90, RR > 20, WBC) | |
| A - Age | Age > 60 years | |
| P - Pleural Effusion | Pleural effusion present on chest X-ray or CT |
WATERFALL Trial Update: Landmark NEJM trial proved that aggressive hydration (> 20 mL/kg bolus, 3 mL/kg/hr) does NOT improve clinical outcomes and triples the risk of fluid overload (heart failure, pulmonary edema). Use MODERATE hydration: Lactated Ringer's 10 mL/kg bolus only if hypovolemic, followed by maintenance 1.5 mL/kg/hr (approx 100-150 mL/hr). Re-evaluate hematocrit and BUN at 12 and 24 hours.
| AMI Subtype | Incidence & Etiology | Clinical Presentation | Diagnostic Hallmark & Therapy |
|---|---|---|---|
| Superior Mesenteric Artery (SMA) Embolus | 50% of cases; cardiac embolus (atrial fibrillation, post-MI mural thrombus) | Sudden, catastrophic periumbilical pain out of proportion to exam; rapid emptying (diarrhea/vomiting) | Biphasic CTA: Abrupt cutoff in mid-to-distal SMA with sparing of proximal jejunal branches. Emergent surgical embolectomy. |
| SMA Thrombosis | 25% of cases; acute thrombosis overlying pre-existing atherosclerotic plaque | Pre-existing history of 'intestinal angina' (postprandial pain, food fear, weight loss); gradual worsening pain | Biphasic CTA: Severe ostial / proximal SMA occlusion with calcification. Emergent surgical bypass or stenting. |
| Non-Occlusive Mesenteric Ischemia (NOMI) | 20% of cases; severe splanchnic vasospasm in low-flow states (shock, high-dose pressors, heart failure) | Critically ill ICU patient on vasopressors with worsening distension, lactic acidosis, and organ failure | CTA: Diffuse narrowing and 'pruning' of mesenteric vessels. Optimize hemodynamics, reduce vasopressors, intra-arterial papaverine. |
| Mesenteric Venous Thrombosis (MVT) | 5-10% of cases; thrombosis of SMV or portal vein due to hypercoagulable state or cirrhosis | Insidious abdominal pain over days/weeks; nausea, vomiting, ascites | CTA: Filling defect in superior mesenteric vein or portal vein. Therapeutic IV Heparin anticoagulation. |
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