1. Mechanical Ventilation Support

Rationale: Sepsis-induced Acute Respiratory Distress Syndrome (ARDS) is a common and serious complication of severe intra-abdominal infections. Early recognition of respiratory failure and prompt initiation of lung-protective ventilation strategies are critical to improving survival and minimizing ventilator-induced lung injury.

Key Indications for Intubation

• Severe Hypoxemia: PaO₂/FiO₂ ratio ≤300 mm Hg despite high-flow nasal cannula or non-invasive ventilation.
• Acute Respiratory Acidosis: Arterial pH < 7.20 with a rising PaCO₂.
• Respiratory Muscle Fatigue: Sustained respiratory rate > 30 breaths/min, use of accessory muscles, or paradoxical abdominal breathing.
• Failure to Protect Airway: Altered mental status (e.g., GCS < 8) with risk of aspiration.

Lung-Protective Ventilation Strategy

For patients with moderate-to-severe ARDS (PaO₂/FiO₂ ≤150), consider prone positioning for 12–16 hours per day and utilize a higher PEEP strategy based on standardized FiO₂/PEEP tables.

Sedation and Analgesia

The goal is to maintain patient comfort while avoiding deep sedation. An “analgesia-first” approach is preferred, using a fentanyl infusion titrated to pain scores. For sedation, propofol or dexmedetomidine are favored over benzodiazepines to reduce the risk of delirium. Target a light level of sedation (RASS -2 to 0) and perform daily sedation interruptions paired with spontaneous breathing trials to facilitate early liberation from the ventilator.

2. Hemodynamic Support

Rationale: Septic shock from intra-abdominal infection causes profound vasodilation and capillary leak, leading to tissue hypoperfusion. The primary goal is to rapidly restore mean arterial pressure (MAP) and organ perfusion with fluids and vasopressors, guided by dynamic assessments.

A. Early Fluid Resuscitation

Administer 30 mL/kg of a balanced crystalloid solution (e.g., Lactated Ringer’s) within the first hour of recognizing septic shock. Subsequent fluid administration should be guided by dynamic assessments of fluid responsiveness, such as passive leg raise (PLR) or stroke volume variation (SVV), rather than static measures like Central Venous Pressure (CVP).

Resuscitation Targets:

• Mean Arterial Pressure (MAP) ≥65 mm Hg
• Urine output ≥0.5 mL/kg/h
• Lactate clearance ≥10% within the first 2 hours

B. Vasopressor Therapy

If hypotension persists after initial fluid resuscitation, vasopressors are required. Norepinephrine is the first-line agent. Vasopressin can be added as a second agent to decrease the norepinephrine requirement and leverage its different mechanism of action.

3. Prophylaxis and Prevention of ICU Complications

Rationale: Critically ill patients are at high risk for preventable complications. Standardized prophylaxis protocols for venous thromboembolism (VTE) and stress ulcers are essential components of ICU care.

A. Venous Thromboembolism (VTE) Prophylaxis

Pharmacologic prophylaxis is recommended for all patients without a contraindication. Low-molecular-weight heparin (LMWH) is generally preferred. Unfractionated heparin (UFH) is a suitable alternative in patients with severe renal impairment or when a high bleeding risk necessitates a shorter half-life.

B. Stress Ulcer Prophylaxis (SUP)

SUP is indicated only for high-risk patients to prevent clinically significant gastrointestinal bleeding. Key risk factors include mechanical ventilation for >48 hours combined with another major risk factor like shock, coagulopathy, or acute liver failure. Proton pump inhibitors (PPIs) are the preferred agent. Prophylaxis should be reassessed daily and discontinued once risk factors resolve to minimize the risk of pneumonia and C. difficile infection.

4. Management of Iatrogenic Complications

Rationale: The life-saving interventions used in the ICU carry their own risks. Vigilant monitoring is required to detect and mitigate drug-induced organ dysfunction and other treatment-related adverse events.

A. Drug-Induced Organ Dysfunction

• Antimicrobials: Monitor renal function (creatinine), liver function tests (LFTs), and complete blood count (CBC) every 48–72 hours to screen for nephrotoxicity, hepatotoxicity, or bone marrow suppression.
• Vasopressors: Regularly assess skin perfusion, lactate trends, and urine output to ensure therapy is improving, not causing, end-organ ischemia.
• Sedatives: Be vigilant for propofol-related infusion syndrome (PRIS), characterized by metabolic acidosis, rhabdomyolysis, and hypertriglyceridemia, especially with high doses or prolonged use.

B. Antimicrobial Stewardship

A core principle of managing complications is to use antimicrobials judiciously. De-escalate the spectrum of antibiotic coverage at 48–72 hours based on clinical response and culture data. For most patients with adequate surgical source control, a short, fixed course of antibiotics (e.g., 4 days) is as effective as longer courses and limits toxicity and resistance.

5. Multidisciplinary Goals-of-Care Conversations

Rationale: Severe intra-abdominal sepsis carries a high mortality and morbidity. It is essential to align intensive medical interventions with the patient’s values and goals through structured, compassionate communication.

These conversations should be a planned, multidisciplinary effort involving surgeons, intensivists, nurses, pharmacists, and palliative care specialists. Using structured communication frameworks like SPIKES or NURSE can help facilitate difficult conversations with families. Key topics include the patient’s likely prognosis, the potential burdens of ongoing or escalating treatments (e.g., ECMO, open abdomen management), and realistic expectations for long-term functional outcomes.

6. Pharmacotherapy Considerations

Rationale: Optimizing the pharmacokinetic and pharmacodynamic properties of critical care medications is key to achieving therapeutic goals while minimizing toxicity. This section provides a focused summary of dosing and monitoring for key drug classes.

Sedatives & Analgesics

The primary strategy is “analgesia-first,” using opioids to treat pain, which often reduces the need for deep sedation. Weaning involves daily interruptions of sedative infusions to assess neurologic function and readiness for extubation, while monitoring for delirium with the CAM-ICU score.