Acute Pancreatitis with Respiratory Failure in ICU: Anaesthetic Approach

1. Immediate priorities: ABCDE approach

A. Airway

• Inability to protect airway, low GCS or encephalopathy
• Refractory hypoxaemia despite oxygen or NIV
• Severe respiratory distress, fatigue, tachypnoea, rising PaCO₂
• Haemodynamic instability or shock
• Need for urgent intervention, transport, or prone ventilation

B. Breathing

• Pulse oximetry and arterial blood gas
• Chest radiograph or bedside lung ultrasound
• Point-of-care echocardiography
• Ultrasound assessment for pleural effusion
• Consider CT pulmonary angiography if pulmonary embolism is suspected and the patient is stable enough

• Early inflammatory lung injury and ARDS
• Atelectasis due to pain, diaphragmatic splinting and abdominal distension
• Pleural effusion, often left-sided
• Pulmonary oedema due to capillary leak or excessive fluid therapy
• Aspiration, pneumonia, sepsis, pulmonary embolism
• Intra-abdominal hypertension or abdominal compartment syndrome impairing diaphragmatic movement

C. Circulation

• Arterial line for beat-to-beat BP and repeated ABG
• Central venous access if vasopressors or multiple infusions are required
• Urinary catheter for hourly urine output
• Temperature monitoring

• MAP at least 65 mmHg, individualized to patient factors
• Urine output at least 0.5 mL/kg/h
• Improving lactate and peripheral perfusion
• Falling or non-rising urea/BUN and haematocrit
• Avoidance of positive fluid balance and worsening oxygenation

2. Assessment of severity and cause

• Onset, severity and radiation of abdominal pain
• Alcohol intake
• Previous gallstones, biliary colic, jaundice or cholangitis
• Hypertriglyceridaemia, hypercalcaemia
• Drugs, recent ERCP, trauma
• Comorbid cardiac, renal, hepatic and respiratory disease

• SIRS, sepsis and shock
• Jaundice or signs of cholangitis
• Abdominal tenderness, guarding, distension, ileus
• Raised intra-abdominal pressure
• Signs of pleural effusion, basal atelectasis, aspiration or pulmonary oedema
• Peripheral oedema and fluid overload

• Complete blood count and haematocrit
• Serum amylase and lipase
• ABG, lactate and glucose
• Urea, creatinine, electrolytes, calcium, magnesium and phosphate
• LFT, bilirubin and coagulation profile
• CRP, procalcitonin where infection is suspected
• Serum triglycerides
• Blood cultures, urine cultures, tracheal aspirate cultures if sepsis is suspected

• Modified Marshall organ failure score
• Serial SOFA score
• APACHE II score in ICU
• SIRS and persistent organ failure
• Rising BUN/urea, haematocrit, creatinine and lactate are concerning

3. Imaging

• Chest radiograph for infiltrates, atelectasis, oedema and effusions.
• Lung ultrasound for B-lines, consolidation, effusions and recruitment response.
• Bedside echocardiography to distinguish hypovolaemia, cardiac dysfunction and fluid overload.
• Transabdominal ultrasound to identify gallstones and biliary dilatation.
• Contrast-enhanced CT abdomen is not routinely needed early only to grade severity. It is useful after 48-72 hours, or earlier if diagnosis is uncertain, deterioration occurs, or complications are suspected.
• CT or MRI later assesses pancreatic necrosis, collections, infection, vascular complications and abdominal pathology.

4. Respiratory support

Non-invasive support

Invasive mechanical ventilation

• Tidal volume: 4-6 mL/kg predicted body weight
• Plateau pressure: keep below 30 cm H₂O
• Driving pressure: keep as low as possible, preferably below 15 cm H₂O
• Individualized PEEP to prevent derecruitment while avoiding haemodynamic compromise
• Titrate FiO₂ to achieve adequate oxygenation, usually SpO₂ 92-96%
• Accept permissive hypercapnia if required, provided severe acidosis, raised intracranial pressure and other contraindications are absent
• Regular ABG, ventilator mechanics and chest imaging

Severe ARDS

• Early prone positioning for prolonged sessions, usually 12-16 hours/day
• Conservative fluid strategy after initial shock has been corrected
• Short-term neuromuscular blockade only if severe ventilator dyssynchrony or refractory hypoxaemia persists despite deep sedation and optimization
• Consider inhaled pulmonary vasodilator as a temporary rescue measure
• Refer early to an ECMO-capable centre for refractory severe hypoxaemia despite optimal conventional ventilation and prone positioning

5. Haemodynamic, renal and metabolic management

• Repeat focused echocardiography and dynamic fluid responsiveness assessment.
• Avoid excessive chloride-rich crystalloid and avoid hydroxyethyl starch.
• Treat persistent shock with noradrenaline.
• Add vasopressin or other agents where indicated in refractory vasodilatory shock.
• Monitor for acute kidney injury with urine output, creatinine, electrolytes and acid-base status.
• Start renal replacement therapy for conventional indications: refractory hyperkalaemia, severe acidosis, pulmonary oedema, uraemic complications or persistent fluid overload.
• Correct hypocalcaemia only if symptomatic, severe or causing arrhythmia. Routine correction of mild asymptomatic hypocalcaemia is not needed.
• Maintain blood glucose control and treat severe hyperglycaemia.
• Monitor and replace magnesium and phosphate.

6. Specific management of acute pancreatitis

Analgesia and sedation

Nutrition

• Do not maintain prolonged “nil by mouth” solely to rest the pancreas.
• Start early enteral nutrition within 24-48 hours once haemodynamically stable.
• Nasogastric feeding is generally acceptable; nasojejunal feeding can be used when gastric feeding is not tolerated.
• Use parenteral nutrition only when enteral feeding is impossible or insufficient.

Antibiotics

• Cholangitis
• Infected pancreatic necrosis
• Pneumonia, aspiration, urinary infection, line sepsis, or another documented/suspected extrapancreatic infection

Biliary pancreatitis

• Acute cholangitis
• Persistent biliary obstruction or jaundice with obstruction

Necrosis and collections

• Sterile necrosis: supportive treatment and observation.
• Suspected infected necrosis: antibiotics that penetrate pancreatic tissue, with image-guided, endoscopic or surgical drainage when indicated.
• Prefer a delayed, step-up approach to intervention where feasible, allowing collections to mature.

7. Intra-abdominal hypertension and abdominal compartment syndrome

• Avoiding excessive fluids
• Adequate analgesia and sedation
• Nasogastric and rectal decompression where appropriate
• Drainage of ascites or collections if feasible
• Optimization of abdominal wall compliance
• Surgical decompression only for refractory abdominal compartment syndrome with organ failure

8. Monitoring, prevention of ICU complications and team management

• ECG, SpO₂, invasive BP, temperature
• Hourly urine output and fluid balance
• Serial ABG, lactate, electrolytes, creatinine, haematocrit and BUN
• Daily SOFA score and organ support requirements
• Sedation, delirium and neuromuscular status
• Intra-abdominal pressure when indicated

• Mechanical and pharmacological DVT prophylaxis unless contraindicated
• Stress ulcer prophylaxis in ventilated/high-risk patients
• Ventilator-associated pneumonia prevention bundle
• Central-line and urinary-catheter infection prevention
• Pressure area care, passive physiotherapy and early mobilization when stable
• Daily review of invasive devices, antibiotics, sedation and feeding

Conclusion

Acute Pancreatitis with Respiratory Failure in ICU

Approach and Management

Introduction

1. Immediate assessment and resuscitation: ABCDE

A. Airway

• GCS ≤ 8 or inability to protect the airway
• Refractory hypoxaemia
• Severe respiratory distress or fatigue
• Hypercapnia with acidosis
• Haemodynamic instability/shock
• Need for prone ventilation or urgent intervention

B. Breathing

• Pulse oximetry and arterial blood gas
• Chest radiograph
• Lung ultrasound for pleural effusion, B-lines, consolidation and atelectasis
• Bedside echocardiography
• Calculate PaO₂/FiO₂ ratio

• Pancreatitis-associated acute lung injury/ARDS
• Pleural effusion
• Basal atelectasis due to pain and diaphragmatic splinting
• Pulmonary oedema from capillary leak or fluid overload
• Aspiration pneumonitis/pneumonia
• Sepsis
• Pulmonary embolism
• Intra-abdominal hypertension/abdominal compartment syndrome

C. Circulation

• Two large-bore intravenous cannulae
• Arterial line
• Urinary catheter for hourly urine output
• Central venous access if vasopressors are required
• ECG, temperature, lactate and serial ABG

• Use balanced crystalloid, preferably lactated Ringer's solution.
• Give cautious, goal-directed fluid boluses if hypovolaemic.
• Reassess repeatedly using MAP, urine output, lactate, haematocrit, urea/BUN, bedside echocardiography and lung ultrasound.
• Avoid excessive fluid administration because it worsens pulmonary oedema, pleural effusion and abdominal compartment syndrome.
• If hypotension persists after appropriate fluid resuscitation, start noradrenaline to maintain MAP ≥65 mmHg.

• MAP ≥65 mmHg
• Urine output ≥0.5 mL/kg/h
• Improving lactate and peripheral perfusion
• Falling/non-rising urea and haematocrit
• No clinical evidence of fluid overload

D. Disability

• GCS and pupils
• Check blood glucose
• Assess pain, agitation and delirium
• Treat severe pain with titrated intravenous opioids

E. Exposure

• Full abdominal examination for distension, guarding, ileus and tense abdomen
• Look for jaundice/cholangitis
• Search for sepsis, line infection, aspiration and pressure injury

2. Assess severity and identify the aetiology

Severity assessment

• SIRS criteria
• SOFA score and serial organ dysfunction assessment
• APACHE II score in ICU
• Modified Marshall organ failure score
• Serial lactate, creatinine, haematocrit and urea/BUN

Investigations

• CBC, haematocrit, platelets
• Serum lipase/amylase
• ABG, lactate and blood glucose
• Urea, creatinine, electrolytes, calcium, magnesium and phosphate
• LFT, bilirubin, coagulation profile
• CRP and procalcitonin where infection is suspected
• Serum triglycerides and calcium
• Blood, urine and respiratory cultures if sepsis is suspected

Determine cause

• Gallstones
• Alcohol
• Hypertriglyceridaemia
• Hypercalcaemia
• Drugs
• Post-ERCP pancreatitis
• Trauma and infection

Imaging

• Ultrasound abdomen: gallstones and biliary dilatation
• Chest radiograph/lung ultrasound: pleural effusion, oedema, atelectasis, infiltrates
• Contrast CT abdomen: if diagnosis is uncertain, deterioration occurs, or after 48-72 h to assess necrosis and collections
• MRCP/EUS if persistent common bile duct stone is suspected

3. Respiratory management

A. Oxygen and non-invasive support

• Supplemental oxygen for mild hypoxaemia.
• High-flow nasal oxygen may be tried in selected cooperative patients.
• NIV may be considered cautiously in mild-moderate respiratory failure, but should not delay intubation in worsening ARDS, vomiting, shock, encephalopathy or acidosis.

B. Invasive mechanical ventilation

• Tidal volume: 4-6 mL/kg predicted body weight
• Plateau pressure: <30 cm H₂O
• Use appropriate PEEP to prevent alveolar collapse
• Titrate FiO₂ to maintain SpO₂ around 92-96%
• Allow permissive hypercapnia when necessary, provided there is no contraindication
• Monitor plateau pressure, driving pressure, ABG and ventilator synchrony

C. Rescue strategies in severe ARDS

• Prone positioning for 12-16 hours/day in persistent moderate-severe ARDS
• Conservative fluid balance after initial resuscitation
• Neuromuscular blockade for severe dyssynchrony or refractory hypoxaemia, for the shortest necessary duration
• Inhaled pulmonary vasodilator as a temporary rescue measure
• Early referral to an ECMO centre for refractory hypoxaemia despite optimized ventilation and prone positioning

4. Management of pancreatitis and associated organ dysfunction

A. Analgesia and sedation

• Intravenous opioid analgesia: fentanyl/remifentanil infusion in ventilated patients.
• Add paracetamol if not contraindicated.
• Adequate analgesia reduces splinting, atelectasis and oxygen consumption.
• Use protocol-based, light sedation whenever feasible.

B. Nutrition

• Start early enteral nutrition within 24-48 hours once haemodynamically stable.
• Nasogastric feeding is usually acceptable.
• Use nasojejunal feeding if gastric feeding is not tolerated.
• Reserve parenteral nutrition for patients in whom enteral nutrition is impossible or inadequate.

C. Antibiotics

• Cholangitis
• Infected pancreatic necrosis
• Pneumonia/aspiration
• Urinary infection, line sepsis or another documented infection

D. Biliary pancreatitis

• Acute cholangitis
• Ongoing biliary obstruction with jaundice

E. Renal support

• Monitor hourly urine output and serum creatinine.
• Avoid nephrotoxic agents and fluid overload.
• Start renal replacement therapy for standard indications: refractory hyperkalaemia, severe acidosis, uraemia or fluid overload refractory to diuretics.

5. Intra-abdominal hypertension and abdominal compartment syndrome

• Tense abdominal distension
• Oliguria or rising creatinine
• Worsening hypoxaemia or high airway pressures
• Refractory shock

• Avoid fluid overload
• Adequate analgesia and sedation
• Nasogastric/rectal decompression when indicated
• Drain ascites or collections where possible
• Consider surgical decompression for refractory abdominal compartment syndrome with organ failure

6. ICU monitoring and supportive care

• Continuous ECG, SpO₂, invasive blood pressure and temperature monitoring
• Hourly urine output and strict fluid balance
• Serial ABG, lactate, electrolytes, creatinine, urea/BUN and haematocrit
• Daily SOFA score and assessment of organ support
• DVT prophylaxis, unless contraindicated
• Stress-ulcer prophylaxis in high-risk/ventilated patients
• Ventilator-associated pneumonia prevention bundle
• Central-line and urinary-catheter care bundles
• Daily review of sedation, antibiotics, invasive lines and enteral nutrition
• Multidisciplinary care involving intensivist, anaesthesiologist, gastroenterologist, surgeon, interventional radiologist and nutrition team

Conclusion

Acute Pancreatitis

Note based on The Washington Manual of Medical Therapeutics

Definition

Aetiology

1. Gallstone disease
2. Alcohol use

• Hypertriglyceridaemia
• Hypercalcaemia
• Drugs
• Abdominal trauma
• Post-ERCP pancreatitis

Clinical features

• Acute severe epigastric pain, often radiating to the back
• Nausea and vomiting
• Pain worsened by food intake
• Fever, tachycardia and abdominal tenderness
• Severe disease may present with dyspnoea, altered sensorium, electrolyte abnormalities, hypotension and shock.

Diagnosis

1. Typical upper abdominal pain, usually radiating to the back
2. Serum lipase or amylase more than three times the upper limit of normal
3. Characteristic radiological findings

Investigations

• CBC, haematocrit
• Serum lipase/amylase
• Electrolytes, calcium, glucose, urea and creatinine
• Liver-function tests to identify biliary obstruction
• Lipid profile to identify hypertriglyceridaemia
• ABG and lactate in severe illness
• Blood cultures if sepsis/infected necrosis is suspected

Imaging

• Ultrasonography: to identify gallstones and biliary dilatation.
• Contrast-enhanced dual-phase CT pancreas: in severe pancreatitis, uncertain diagnosis, failure to improve after 48-72 hours, or suspected complications.
• CT performed too early may underestimate severity.
• MRCP: useful to identify biliary obstruction before ERCP.
• MRI: an alternative when CT contrast is contraindicated.

Management

1. Fluid resuscitation

• Start early, goal-directed IV crystalloid resuscitation.
• Ringer's lactate is preferred to normal saline.
• The Washington Manual describes an initial regimen of 20 mL/kg bolus followed by 3 mL/kg/hour, with frequent reassessment.
• Monitor:
  • Blood pressure and perfusion
  • Urine output
  • Fluid balance
  • Haematocrit
  • Urea/creatinine
  • Electrolytes, calcium and glucose
  • Signs of pulmonary oedema and abdominal fluid sequestration

2. Analgesia

• Opioid analgesics are usually required.
• Titrate IV fentanyl, morphine, or another suitable opioid according to pain, respiratory status and haemodynamics.

3. Nutrition

• Resume oral intake within 24 hours if tolerated.
• If nutritional needs cannot be met by 72 hours, initiate nasogastric or nasoenteric feeding.
• Enteral nutrition is preferred over parenteral nutrition.
• Gastric and jejunal feeding have similar outcomes in severe acute pancreatitis.

4. Antibiotics

• Routine prophylactic antibiotics are not recommended.
• Use broad-spectrum antibiotics only with documented infection or a high suspicion of infected necrosis, cholangitis, pneumonia, or another infective focus.
• In infected pancreatic necrosis, antimicrobial options with good penetration include a carbapenem or a fluoroquinolone plus metronidazole, guided by cultures and local policy.

5. Biliary pancreatitis

• Urgent ERCP with biliary sphincterotomy is indicated in severe gallstone pancreatitis with cholangitis.
• Urgent ERCP has no established benefit in the absence of cholangitis.
• Perform cholecystectomy during the same admission for acute gallstone pancreatitis, once clinically appropriate.

Complications

Local complications

• Pancreatic necrosis
• Infected necrosis
• Pancreatic pseudocyst
• Pancreatic abscess
• Haemorrhage/pseudoaneurysm
• Pancreatic ascites
• Gastric or biliary obstruction

Systemic complications

• Shock and multiorgan dysfunction
• ARDS
• Atelectasis, pleural effusion and pneumonia
• Acute kidney injury due to hypovolaemia or acute tubular necrosis
• Electrolyte disturbance, especially hypocalcaemia
• Stress-related gastrointestinal bleeding
• DIC and venous thromboembolism

Infected pancreatic necrosis

• Persistent or worsening abdominal pain
• Fever
• Marked leucocytosis
• Bacteraemia
• Deteriorating organ function

ICU indications

• Persistent hypotension or shock
• Respiratory failure, hypoxaemia or ARDS
• Acute kidney injury/oliguria
• Altered sensorium
• Persistent SIRS or multiorgan dysfunction
• Severe metabolic derangement
• Suspected infected necrosis or abdominal compartment syndrome