Aspiration risk

What is aspiration and why it matters

• Aspiration = stomach contents entering the airway/lungs (often during reduced consciousness or airway manipulation).
• Main harms: airway obstruction, chemical pneumonitis (acid injury), infection (aspiration pneumonia), hypoxia, bronchospasm, ARDS.
• Risk is highest at induction, during airway instrumentation, and at emergence/extubation.

Core concept: aspiration risk = (full stomach) + (unprotected airway)

• “Full stomach” can be due to recent eating/drinking, delayed gastric emptying, obstruction, or reflux.
• “Unprotected airway” means no cuffed tracheal tube (e.g., facemask, supraglottic airway, deep sedation).
• Even with a tracheal tube, regurgitation can still occur (e.g., around cuff or before cuff inflated).

Common high-risk patients and situations (first-time scenarios)

• Emergency surgery: trauma, acute abdomen, bowel obstruction, sepsis (often not fasted).
• Pregnancy (especially 2nd/3rd trimester and labour): reflux risk and reduced lower oesophageal sphincter tone.
• Obesity and obstructive sleep apnoea: difficult airway + reflux more likely.
• GORD/hiatus hernia: higher regurgitation risk (symptoms matter).
• Diabetes with gastroparesis, opioid use, severe pain, ileus: delayed gastric emptying.
• Upper GI pathology: obstruction, bleeding, persistent vomiting.
• Sedation outside theatre (endoscopy, ED): reduced airway reflexes without a secured airway.

Fasting basics (adult elective, typical UK practice)

• Aim: reduce gastric volume and acidity, but fasting does not eliminate aspiration risk.
• Typical minimums: 6 hours for solids/light meal; 2 hours for clear fluids.
• Clear fluids = water, black tea/coffee (no milk), pulp-free juice; milk counts as a solid.
• If fasting status is uncertain, treat as full stomach and escalate plan.

Pre-op assessment: quick aspiration risk screen

• Ask: When did you last eat/drink? What exactly? Any vomiting or reflux today?
• Look for: pregnancy, obesity, diabetes, bowel obstruction, opioids, severe pain, sepsis, reduced consciousness.
• Consider airway plan: anticipated difficulty increases risk because airway instrumentation may be prolonged.
• Document fasting status and aspiration risk in the anaesthetic plan; communicate with the team.

Reducing risk: practical steps before induction

• Positioning: head-up (ramped in obesity) to improve pre-oxygenation and reduce regurgitation risk.
• Choose the safest technique: full-stomach patients often need rapid sequence induction (RSI) with cuffed tracheal tube.
• Have suction working and immediately available; consider two suctions for very high risk.
• Plan for difficulty: ensure skilled help, airway adjuncts, videolaryngoscope availability, and a clear failed-intubation plan.
• Consider aspiration prophylaxis when appropriate (local policy): non-particulate antacid (e.g., sodium citrate), H2 blocker, or PPI; prokinetic (e.g., metoclopramide) in selected cases.

Airway management choices: when to avoid a supraglottic airway (SGA)

• Avoid SGA as the primary airway in high aspiration risk (e.g., bowel obstruction, active vomiting, not fasted emergency).
• SGA may be acceptable in low-risk fasted elective cases, but it does not fully protect against aspiration.
• If using an SGA, ensure adequate depth, avoid overinflation, and be ready to convert to intubation if regurgitation occurs.

RSI essentials (introductory, safety-focused)

• Goal: minimise time between loss of airway reflexes and cuff inflation.
• Key steps: thorough pre-oxygenation, head-up/ramped position, induction + fast-onset neuromuscular blocker, prompt laryngoscopy and intubation, confirm tube position, inflate cuff early.
• Cricoid pressure: use only if trained and per local practice; release if it worsens view/ventilation or causes difficulty.
• If intubation fails: follow the failed intubation/obstetric general anaesthesia algorithm; prioritise oxygenation.

If regurgitation/aspiration happens: immediate actions

• Call for help early; prioritise oxygenation and airway control.
• Turn head to the side and head-down tilt if feasible (reduce further aspiration).
• Suction the mouth/pharynx immediately; suction through the tracheal tube after intubation.
• Secure the airway with a cuffed tracheal tube as soon as possible (if not already).
• Ventilate with 100% oxygen; treat bronchospasm if present (e.g., deepen anaesthesia, bronchodilators).
• Consider bronchoscopy if particulate matter suspected or persistent obstruction.
• Post-event: monitor closely (oxygenation, chest signs, CXR if indicated), document clearly, and hand over to recovery/ICU.

Post-op considerations after suspected aspiration

• Not all aspiration needs antibiotics: chemical pneumonitis is inflammatory; antibiotics if infection suspected (fever, rising inflammatory markers, purulent sputum, consolidation) or high risk of contaminated aspirate.
• Observe for delayed deterioration (hypoxia, increased work of breathing) for several hours; low threshold for HDU/ICU if significant event.
• Provide clear patient communication and safety-netting; complete incident reporting per local policy.