21.1 Acute Upper & Lower Gastrointestinal Bleeding in the ICU

Resuscitation Physiology and Restrictive Transfusion Strategy

Acute gastrointestinal bleeding (GIB) represents one of the most frequent causes of admission to the intensive care unit. Critical care management begins with rapid assessment of airway stability, intravascular volume resuscitation, and correction of physiological derangements before definitive diagnostic endoscopic localization.

The Villanueva Trial and Transfusion Physiology

Historically, clinicians resuscitated acute upper gastrointestinal bleeding (UGIB) with liberal blood transfusions targeting normal hemoglobin levels ($>10\text{ g/dL}$). However, the seminal multicenter randomized controlled trial by Villanueva et al. (NEJM 2013) transformed clinical practice by demonstrating the superiority of a restrictive transfusion strategy:

• Restrictive Strategy: Packed red blood cells (PRBCs) transfused only when hemoglobin dropped below $7\text{ g/dL}$, targeting a post-transfusion hemoglobin of $7-8\text{ g/dL}$.
• Liberal Strategy: PRBCs transfused when hemoglobin dropped below $9\text{ g/dL}$, targeting a hemoglobin of $9-11\text{ g/dL}$.

In this landmark trial of 921 patients, the restrictive transfusion strategy demonstrated a statistically significant reduction in all-cause 6-week mortality (5% vs. 9%, hazard ratio 0.55; $P = 0.02$), a marked decrease in recurrent bleeding (10% vs. 16%; $P = 0.01$), and significantly fewer overall adverse events (40% vs. 48%; $P = 0.02$). The survival benefit was most pronounced in patients with cirrhosis and Child-Pugh class A and B disease.

[Acute Severe Gastrointestinal Hemorrhage]
                   │
       Hemodynamic Assessment & Access
   (2 large-bore peripheral IVs or Cordis)
                   │
   ┌───────────────┴───────────────┐
   ▼                               ▼
Cirrhotic / Variceal Suspicion    Non-Variceal Presentation
   │                               │
   ├─ Octreotide Bolus + Infusion  ├─ High-Dose IV PPI (80 mg bolus)
   ├─ Ceftriaxone 1 g IV daily     ├─ Restrictive PRBC (Trigger Hgb < 7)
   ├─ Restrictive PRBC (Hgb 7-8)   └─ Urgent EGD within 24 Hours
   ├─ Urgent EGD within 12 Hours
   └─ High Risk? Early TIPS (24-72h)

Exceptions to Restrictive Strategy: A restrictive threshold ($<7\text{ g/dL}$) applies universally to stable and critically ill patients with acute UGIB, except those with ongoing acute myocardial ischemia, symptomatic coronary artery disease, or active refractory exsanguinating hemorrhagic shock, where a higher hemoglobin target of $8-9\text{ g/dL}$ is prudent.

Airway Protection and Pre-Endoscopic Pharmacotherapy

Patients presenting with ongoing massive hematemesis, depressed level of consciousness (Glasgow Coma Scale $<8$), or severe hepatic encephalopathy require elective endotracheal intubation prior to upper endoscopy to prevent catastrophic pulmonary aspiration of blood and gastric contents. Intubation should be performed using rapid sequence induction with hemodynamic optimization to prevent post-induction circulatory collapse.

Erythromycin Administration: Intravenous erythromycin ($250\text{ mg}$ IV infused over $30-60\text{ minutes}$, administered $30-90\text{ minutes}$ prior to EGD) acts as a motilin receptor agonist. It accelerates gastric emptying, clears blood, organized clots, and food residues from the gastric fundus and antrum, significantly improving mucosal visualization, shortening procedural duration, and reducing the requirement for a second-look endoscopy.

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Non-Variceal Upper GI Bleeding: Peptic Ulcer Disease & Forrest Classification

Peptic ulcer disease (PUD)—encompassing duodenal and gastric ulcers—accounts for 50% to 60% of all acute non-variceal UGIB admissions. Arterial hemorrhage occurs when acid-peptic ulceration erodes deeply through the submucosa and muscularis propria into major underlying vessels, such as the gastroduodenal artery (posterior duodenal bulb ulcers) or the left gastric artery (lesser curvature gastric ulcers).

Forrest Classification and Risk Stratification

The Forrest classification categorizes bleeding peptic ulcers based on their endoscopic stigmata of recent hemorrhage, directly determining rebleeding risk and guiding the necessity for endoscopic hemostatic therapy:

Dual Endoscopic Therapy Paradigm

Guidelines strictly mandate that endoscopic injection of dilute epinephrine ($1:10,000$ or $1:20,000$) must never be utilized as monotherapy. While local epinephrine injection produces transient interstitial tamponade and arteriolar vasoconstriction, it does not achieve definitive vessel thrombosis and yields unacceptably high rates of secondary rebleeding.

Epinephrine injection must always be paired with a second, definitive hemostatic modality:

1. Thermal Contact Devices: Bipolar electrocoagulation or heater probe thermocoagulation applies physical coaptive pressure to compress the vessel lumen, followed by thermal energy delivery to seal the arterial walls.
2. Mechanical Devices: Through-the-scope clips (TTSC) or over-the-scope clips (OTSC) physically grasp and appose the bleeding vessel and surrounding fibrotic submucosa, achieving immediate mechanical occlusion without inducing additional tissue necrosis. OTSC systems are particularly effective for large ($>1.5-2\text{ cm}$), fibrotic, chronic ulcers where conventional TTS clips fail.
3. Topical Hemostatic Agents: Hemostatic powders (e.g., TC-325) provide rapid temporary bridging in diffuse, friable oozing malignant lesions or massive bleeding where direct vessel localization is obscured.

Acid Suppression Physiology

Gastric acid profoundly inhibits hemostasis: at a $\text{pH} < 6.0$, platelet aggregation is abolished, platelet disaggregation occurs, and pepsinogen is activated to pepsin, which actively lyses newly formed fibrin clots. Maintaining an intragastric $\text{pH} \ge 6.0$ stabilizes the hemostatic clot.

• High-Dose Intravenous PPI Regimen: Intravenous omeprazole or pantoprazole administered as an $80\text{ mg}$ IV bolus, followed by a continuous infusion of $8\text{ mg/h}$ for 72 hours (the window during which $>80\%$ of ulcer rebleeding occurs).
• Intermittent Dosing Non-Inferiority: Multiple meta-analyses have demonstrated that high-dose intermittent IV PPI (e.g., pantoprazole $40-80\text{ mg}$ IV twice daily) achieves equivalent 72-hour rebleeding rates, surgical interventions, and mortality compared to continuous infusion regimens.

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Acute Variceal Hemorrhage Emergency Management Protocol

Esophageal and gastric varices develop as collateral circulations secondary to portal hypertension. The hepatic venous pressure gradient (HVPG)—the difference between the wedged hepatic venous pressure and the free hepatic venous pressure—reflects portal pressure. Normal HVPG is $1-5\text{ mmHg}$. An $\text{HVPG} \ge 10\text{ mmHg}$ defines clinically significant portal hypertension, and an $\text{HVPG} \ge 12\text{ mmHg}$ represents the critical threshold required for variceal formation and rupture.

Pre-Endoscopic Medical Triad

When variceal hemorrhage is suspected in a patient with chronic liver disease, three medical interventions must be initiated immediately, well before endoscopic intervention:

[Suspected Variceal Upper GI Bleeding]
                   │
       Immediate Medical Stabilization
  ┌────────────────┼────────────────┐
  ▼                ▼                ▼
Splanchnic       Antibiotic      Restrictive
Vasoconstrictor  Prophylaxis     Transfusion
(Octreotide)     (Ceftriaxone)   (Hgb 7-8 g/dL)

1. Vasoactive Splanchnic Infusions

Vasoactive drugs reduce splanchnic arterial blood flow and decrease portal inflow, thereby rapidly lowering portal venous pressure and HVPG:

• Octreotide: A synthetic somatostatin analogue. Initiated as an immediate intravenous bolus of $50\ \mu\text{g}$ IV, followed by a continuous infusion of $50\ \mu\text{g/h}$, maintained for 2 to 5 days.
• Terlipressin: A synthetic vasopressin analogue with selective $V_1$ vascular receptor agonism (bolus $2\text{ mg}$ IV every 4 hours, titrated down to $1\text{ mg}$ q4h). While standard in Europe and internationally, octreotide remains the primary agent in North American centers.

2. Antimicrobial Prophylaxis

Cirrhotic patients presenting with acute UGIB suffer profound reticuloendothelial dysfunction, bacterial translocation from gut congestion, and high rates of spontaneous bacterial peritonitis (SBP), pneumonia, and bacteremia. Systemic infections stimulate endothelial endothelin and nitric oxide imbalances, precipitating rebound portal pressure surges and rebleeding.

• Ceftriaxone: Administered as $1\text{ g}$ IV every 24 hours for 7 days. Ceftriaxone significantly reduces bacterial infections, reduces the incidence of early recurrent bleeding, and provides a proven all-cause mortality benefit in cirrhotic patients with GI hemorrhage.

3. Restrictive PRBC Transfusion

Targeting hemoglobin between $7$ and $8\text{ g/dL}$ avoids portal pressure spikes and secondary rupture.

Endoscopic Intervention

Urgent upper endoscopy should be performed as soon as resuscitation is established, ideally within 12 hours of presentation:

• Esophageal Varices: Endoscopic Variceal Ligation (EVL) is the definitive first-line endoscopic treatment. Elastic rubber bands are deployed over the variceal columns starting at the gastroesophageal junction and spiraling cephalad. EVL is vastly superior to endoscopic sclerotherapy, with significantly higher initial hemostasis rates, lower rebleeding rates, and fewer complications (e.g., esophageal strictures, deep ulcerations, or mediastinitis).
• Gastric Varices: Isolated gastric fundal varices (IGV1) or gastroesophageal varices extending along the fundus (GOV2) are driven by high-flow splenorenal shunts. EVL on large fundal varices carries a high risk of catastrophic tearing and rebleeding upon band sloughing. The preferred endoscopic therapy is endoscopic cyanoacrylate tissue adhesive glue injection (monomer polymerization upon blood contact seals the vascular lumen) or emergent radiological intervention.

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Refractory Variceal Hemorrhage: Balloon Tamponade and Preemptive TIPS

Approximately $10-15\%$ of patients with acute variceal hemorrhage experience failure of medical and endoscopic therapy, manifesting as persistent active bleeding or massive hemodynamic instability.

Balloon Tamponade (Sengstaken-Blakemore and Minnesota Tubes)

Balloon tamponade devices provide mechanical compression against the bleeding varices at the gastroesophageal junction and gastric cardia. Tamponade is strictly an emergency salvage procedure and temporary bridge ($<24\text{ hours}$) to definitive endovascular or surgical shunt therapy.

Sengstaken-Blakemore Tube Deployment Protocol:

1. Endotracheal Intubation (Mandatory prior to insertion)
2. Test Balloons Under Water for Leaks
3. Insert Lubricated Tube via Mouth/Nose into Stomach (>50 cm mark)
4. Insufflate Gastric Balloon with 50 mL Air -> Confirm in Stomach via X-Ray
5. Complete Gastric Insufflation to 250-300 mL Air -> Clamp Lumen
6. Apply 0.5 - 1.0 kg Continuous Traction (Taped to Helmet / C-Collar)
7. Bleeding Persists? -> Inflate Esophageal Balloon to 30-45 mmHg via Manometer
8. Maximum Duration: 24 Hours (Deflate Esophageal Balloon 5 min every 6 hours)

Early Preemptive TIPS

The landmark trial by García-Pagán et al. (NEJM 2010) demonstrated that an early preemptive Transjugular Intrahepatic Portosystemic Shunt (TIPS) placed within 24 to 72 hours of admission significantly reduces treatment failure (rebleeding) and 1-year mortality compared to standard medical plus endoscopic therapy in high-risk cirrhotic patients:

• High-Risk Criteria:
  1. Child-Pugh class C (score 10 to 13 points); OR
  2. Child-Pugh class B (score $\ge 7$ points) with active bleeding identified at diagnostic endoscopy despite ongoing vasoactive infusion.

TIPS creates an expandable low-resistance polytetrafluoroethylene (PTFE)-covered metallic stent between the high-pressure portal vein and the low-pressure hepatic vein, dramatically decompressing the portal venous system and eliminating the underlying driver of variceal rupture.

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Acute Lower Gastrointestinal Bleeding (LGIB) in the ICU

Acute lower gastrointestinal bleeding (LGIB) refers to bleeding originating anatomically distal to the ligament of Treitz, encompassing the small bowel, colon, and anorectum. Severe, hemodynamically significant LGIB in the ICU is predominantly arterial or rapid mucosal capillarovenous hemorrhage.

Primary Etiologies in Critical Care

1. Diverticular Hemorrhage: The most common cause of massive arterial LGIB ($30-40\%$ of cases). Typically presents as acute, painless, large-volume hematochezia. Bleeding results from asymmetric transmural mechanical stress at the fundus of the diverticulum, where penetrating nutrient arterioles (vasa recta) stretch and erode over the dome.
2. Angiodysplasia (Arteriovenous Malformations): Dilated, tortuous submucosal venules and capillaries, most commonly found in the cecum and ascending colon of elderly patients ($>65$ years). Associated with end-stage renal disease and aortic stenosis (Heyde syndrome, where shear stress through the stenotic aortic valve cleaves high-molecular-weight multimers of von Willebrand factor, inducing acquired Type 2A vWD).
3. Ischemic Colitis: Driven by transient non-occlusive low-flow states (systemic hypotension, shock, cardiac surgery, high-dose vasopressors). Classically involves "watershed" regions with tenuous collateral networks: Griffiths' point (splenic flexure, between superior and inferior mesenteric arteries) and Sudeck's point (rectosigmoid junction). Patients characteristically present with acute, crampy lower abdominal pain followed within 12 to 24 hours by bloody diarrhea (rarely massive).

Diagnostic and Interventional Algorithm

[Acute Massive Lower GI Bleeding in ICU]
                   │
   Hemodynamically Unstable / Exsanguinating?
        ├── YES ──> Exclude Upper Source (Brisk duodenal ulcer in 10-15%)
        │           │ (Urgent NG Lavage or Bedside EGD)
        │           ▼
        │     Urgent Multiphase Abdominal CTA (No oral contrast)
        │           │
        │           ├── Extravasation Seen (Rate ≥0.3-0.5 mL/min)
        │           │     └── Urgent Catheter Angiography + TAE (Microcoils)
        │           └── Negative CTA ──> Resuscitate + Colonoscopy Purge
        │
        └── NO  ──> Hemodynamically Stable / Resuscitated
                    │
                    ├── Rapid Polyethylene Glycol (PEG) Purge (4-6 L)
                    └── Early Colonoscopy within 24 Hours