From the Guidelines
Aspiration under general anesthesia is a rare but serious complication, with an incidence of 1 in 7000 and a mortality rate of 1 in 100,000, and can be prevented with proper fasting and airway management techniques, such as rapid sequence induction and cricoid pressure, as recommended by recent studies 1. The risks of aspiration under general anesthesia are multifactorial and can be influenced by various patient-related and procedure-related factors.
- Patient-related factors include:
- Full stomach
- Gastroesophageal reflux disease
- Obesity
- Pregnancy
- Procedure-related factors include:
- Emergency surgery
- Difficulty with airway management To minimize the risk of aspiration, patients should fast before surgery, typically 6-8 hours for solid food and 2 hours for clear liquids, although recent studies suggest that shorter fasting times may be acceptable in certain situations 1. For patients at high risk of aspiration, rapid sequence induction should be performed, which involves preoxygenation, administration of a rapid-acting induction agent, and application of cricoid pressure until the airway is secured with an endotracheal tube 1. Pharmacological prophylaxis may also be considered, including administering a proton pump inhibitor or an H2 blocker to reduce gastric acidity, and metoclopramide to enhance gastric emptying. If aspiration does occur, immediate management includes suctioning the airway, providing 100% oxygen, positioning the patient head-down, and considering bronchoscopy for removal of particulate matter, as recommended by recent studies 1. Aspiration pneumonitis may develop within hours and can lead to acute respiratory distress syndrome, requiring supportive care including mechanical ventilation and, in some cases, antibiotics if infection develops. Recent studies have shown that the incidence of aspiration is declining, and that the current focus on fasting may be misguided, with some studies suggesting that shorter fasting times may be acceptable in certain situations 1. However, it is essential to note that the risk of aspiration is still present, and that proper airway management techniques, such as rapid sequence induction and cricoid pressure, are crucial in preventing this complication, as recommended by recent studies 1.
From the Research
Risks of Aspiration under General Anesthesia
The risks of aspiration under general anesthesia are significant and can lead to serious complications, including:
- Aspiration pneumonia
- Acute respiratory distress syndrome
- Pulmonary edema
- Long-term complications such as laryngotracheal damage and decreased lung compliance 2
- Mortality, with aspiration-related complications reported to cause 10% to 30% of anesthesia-related deaths 2
Factors Contributing to Aspiration Risk
Several factors contribute to the likelihood of aspiration, including:
- Urgency of surgery
- Airways problems
- Inadequate depth of anaesthetic
- Use of the lithotomy position
- Gastrointestinal problems
- Depressed consciousness
- Increased severity of illness
- Obesity 3
- Recent ingestion of food, depression of consciousness and airways reflexes, and gastric stasis induced by raised sympathoadrenal tone, particularly in trauma patients 3
Preventive Measures
Preventive measures can be taken to reduce the risk of aspiration, including:
- Preoperative risk assessment
- Adherence to fasting rules
- Proper patient positioning
- Use of protective airway devices
- Administration of drugs such as proton pump inhibitors to lower stomach acidity and volume 4
- Use of antacids, such as sodium citrate, for highly aspiration-endangered patients, and proton pump inhibitors or H2 blockers for other patients 5
- Rapid sequence induction and intubation (RSI) in patients at risk for aspiration, with optimal drug pre-treatment and expertise and competence of the physician 5
Management of Aspiration
In the event of aspiration, management strategies include:
- Intensive medical monitoring
- Fiber-optic bronchoscopy
- X-ray thorax image or CT scan if symptoms arise
- Admission to an intensive care unit for further observation and therapy if symptoms last for more than two hours in the recovery room 6