For a US paramedic, what is the complete EMS management and treatment protocol for peritonitis from the initial call through transport—including specific medications, dosages, and administration timing—and, if the peritonitis is chronic, which medications might the patient already be taking, their mechanisms, and the complications of delayed treatment?

EMS Management and Treatment of Peritonitis: US Paramedic Protocol

For suspected peritonitis in the prehospital setting, paramedics should focus on rapid fluid resuscitation, pain management, immediate transport, and early notification of the receiving facility—definitive treatment requires emergency surgical intervention that cannot be provided in the field.

Initial Assessment and Recognition

When responding to a call for abdominal pain, look for these specific clinical findings that suggest peritonitis:

• Abdominal rigidity on palpation (board-like abdomen)
• Peritonism (generalized rigidity across the entire abdomen) - this is an ominous sign requiring immediate transport 1
• Diffuse peritonitis (pain throughout the abdomen) versus localized peritonitis (one area)
• Fever, tachycardia, hypotension (signs of septic shock)
• Patient lying still, knees drawn up, refusing to move
• Rebound tenderness, guarding

Critical distinction: Diffuse peritonitis with generalized rigidity indicates catastrophic intra-abdominal pathology requiring emergency surgery 1, 2.

Immediate Prehospital Management Protocol

1. Fluid Resuscitation (HIGHEST PRIORITY)

Begin aggressive IV fluid resuscitation immediately upon suspicion of peritonitis 2:

• Establish two large-bore IV lines (18-gauge or larger)
• Administer 0.9% Normal Saline or Lactated Ringer's
  • Initial bolus: 20 mL/kg (approximately 1-2 liters for average adult) given rapidly
  • For septic shock (SBP <90 mmHg): Continue fluid boluses of 500-1000 mL every 10-15 minutes
  • Reassess vital signs after each bolus
  • Target: SBP >90 mmHg, improved mental status, urine output

Rationale: Patients with peritonitis develop severe third-spacing of fluids into the peritoneal cavity and systemic inflammatory response, leading to profound intravascular volume depletion 2.

2. Pain Management

Administer analgesia—pain control does NOT mask peritonitis and improves patient assessment 3:

• Morphine Sulfate: 2-4 mg IV every 5-10 minutes
  • Titrate to pain relief (typically 0.1 mg/kg total dose)
  • Maximum initial dose: 10 mg
  • Monitor respiratory rate (hold if <10 breaths/min)
  • Have naloxone ready

Alternative if morphine unavailable:

• Fentanyl: 50-100 mcg IV every 5 minutes (faster onset, shorter duration)

3. Oxygen and Airway Management

• Apply high-flow oxygen via non-rebreather mask at 15 L/min
• Monitor SpO2, maintain >94%
• If altered mental status or respiratory distress: prepare for assisted ventilation
• Position patient in position of comfort (usually supine with knees flexed)

4. Monitoring and Documentation

• Continuous cardiac monitoring
• Vital signs every 5 minutes if unstable, every 10-15 minutes if stable
• Document:
  • Time of symptom onset
  • Character and location of pain
  • Presence/absence of fever
  • Last oral intake
  • Recent surgeries or procedures
  • Medications patient is taking (see below)

5. Transport Considerations

Transport immediately—do NOT delay for additional interventions 2:

• Lights and sirens transport for diffuse peritonitis or septic shock
• Early notification to receiving facility: "Suspected peritonitis with septic shock, ETA X minutes, two large-bore IVs established, fluids running wide open"
• Continue fluid resuscitation en route
• Transport time should not exceed on-scene time—the definitive treatment is surgical source control 1, 2

Medications NOT in Standard Paramedic Scope

Paramedics should NOT administer antibiotics in the field 2. While guidelines emphasize that antimicrobial therapy should begin as soon as peritonitis is suspected, this occurs in the emergency department, not prehospital. The evidence shows protocol-based paramedic care focusing on supportive measures (fluids, oxygen, pain control) is safe and effective 4.

Chronic Peritonitis: Peritoneal Dialysis Patients

Medications PD Patients May Already Be Taking

If the patient mentions they are on peritoneal dialysis, they may have chronic/recurrent peritonitis and could be on:

1. Intraperitoneal Antibiotics 5, 6:

• Aminoglycosides (gentamicin or tobramycin): 0.6 mg/kg/day in dialysate

  • What it does: Kills gram-negative bacteria in the peritoneal cavity
  • Given directly into the peritoneal dialysis fluid

• Cephalosporins (cefazolin or cephradine): 15-20 mg/kg/day in dialysate

  • What it does: Kills gram-positive bacteria (Staphylococcus species)

2. Oral Antibiotics (if on outpatient treatment):

• Various combinations depending on culture results

3. Other PD-Related Medications:

• Phosphate binders (calcium acetate, sevelamer)
• Erythropoiesis-stimulating agents (for anemia)
• Vitamin D analogs
• Antihypertensives

Key Point for Paramedics

If patient states they have a peritoneal dialysis catheter and cloudy dialysate fluid, this is PD-associated peritonitis—still requires emergency department evaluation but may be less immediately life-threatening than surgical peritonitis 5. However, treat the same way with aggressive supportive care and rapid transport.

Complications of Delayed Treatment

Untreated peritonitis progresses through a predictable cascade of life-threatening complications 1, 7:

1. Intra-Abdominal Hypertension (IAH) and Abdominal Compartment Syndrome (ACS)

How it develops:

• Peritoneal inflammation → fluid accumulation and bowel edema
• Increased intra-abdominal pressure compresses blood vessels
• Mortality: 75.9% to nearly 100% if not emergently decompressed 1

Clinical signs:

• Tense, distended abdomen
• Worsening hypotension despite fluids
• Decreased urine output
• Respiratory distress (diaphragm pushed up)

2. Septic Shock and Multi-System Organ Failure (MSOF)

Progression 1, 7:

• Bacteria and toxins from peritoneal cavity → bloodstream
• Systemic inflammatory response syndrome (SIRS)
• Vasodilation and capillary leak
• Cardiovascular collapse: Profound hypotension, requires vasopressors
• Respiratory failure: ARDS, pulmonary edema
• Renal failure: Acute kidney injury from hypoperfusion
• Hepatic dysfunction: Coagulopathy, jaundice
• CNS dysfunction: Altered mental status, coma

Timeline: Can progress from localized peritonitis to septic shock within 6-12 hours without treatment 2.

3. Abscess Formation

• Localized pockets of infection
• Require percutaneous or surgical drainage
• Source of ongoing sepsis

4. Intestinal Ischemia and Necrosis

• IAH compresses mesenteric blood vessels
• Bowel wall becomes ischemic → necrosis → perforation
• Creates more contamination, worsening peritonitis

5. Death

Mortality rates 7:

• Community-acquired peritonitis with prompt treatment: 5-10%
• Healthcare-associated peritonitis: 20-30%
• Delayed treatment >24 hours: 40-60%
• Abdominal compartment syndrome: 75-100% 1

Critical Pitfalls to Avoid

1. DO NOT delay transport for additional IV attempts—one IV is sufficient if second attempt fails; start fluids and go

2. DO NOT withhold pain medication—outdated teaching that analgesia "masks" peritonitis is false and harmful

3. DO NOT give oral fluids—patient will need emergency surgery; NPO status required

4. DO NOT assume "stable" vital signs mean stable patient—peritonitis patients can decompensate rapidly; early aggressive treatment prevents deterioration

5. DO NOT attempt to differentiate surgical causes in the field—appendicitis, perforated ulcer, diverticulitis, bowel perforation all require emergency surgery; your job is resuscitation and transport 2

6. DO NOT give antibiotics prehospital—not in paramedic scope and delays transport; antibiotics begin in ED 2

Summary Algorithm

Suspected Peritonitis → Establish 2 large-bore IVs → Aggressive NS/LR boluses (20 mL/kg) → Morphine 2-4 mg IV for pain → High-flow O2 → Continuous monitoring → IMMEDIATE TRANSPORT → Early hospital notification → Continue fluid resuscitation en route

Time is tissue—every hour of delay increases mortality. The paramedic's role is rapid recognition, aggressive supportive care, and expedited transport to definitive surgical source control 1, 2.