39: Aspiration

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CHAPTER 39 Aspiration

Malcolm Packer, MD

1 What is aspiration and what differentiates aspiration pneumonitis from aspiration pneumonia?

Aspiration is the passage of material from the pharynx into the trachea. Aspirated material can originate from the stomach, esophagus, mouth, or nose. The materials involved can be particulate such as food or a foreign body or fluid such as blood, saliva, or gastrointestinal contents. Aspiration of gastric contents may occur by vomiting, which is an active propulsion from the stomach up the esophagus, or by regurgitation, which is the passive flow of material along the same path.

Aspiration pneumonitis describes the initial imflammatory response after aspiration, and aspiration pneumonia describes the consolidation along with the imflammation.

2 How often does aspiration occur and what is the morbidity and mortality rate?

The results of several different retrospective and prospective surveys of adult anesthetics place the incidence at one to seven cases of significant aspiration per 10,000 anesthetics. Studies of children’s anesthetics demonstrate about twice that occurrence. The average hospital stay is 21 days, much of which is in intensive care. Complications range from bronchospasm and pneumonia to acute respiratory distress syndrome, lung abscess, and empyema. The average mortality rate is 5%.

3 What are risk factors for aspiration?

image Extremes of age
image Emergency cases
image Type of surgery (most common in cases of esophageal, upper abdominal, or emergency laparotomy surgery)
image Recent meal (Preoperative fasting guidelines for elective surgery are discussed in Chapter 17.)
image Delayed gastric emptying and/or decreased lower esophageal sphincter tone (diabetes, gastric outlet obstruction, hiatal hernia
image Medications (e.g., narcotics, anticholinergics)
image Trauma
image Pregnancy
image Pain and stress
image Depressed level of consciousness
image Morbid obesity (including after bariatric surgery and the resulting weight loss)
image Difficult airway
image Neuromuscular disease (impaired ability to protect the trachea)
image Esophageal disease (e.g., scleroderma, achalasia, diverticulum, Zenker’s diverticulum)

4 What precautions before anesthetic induction are required to prevent aspiration or mollify its sequelae?

The main precaution is to recognize which patients are at risk. Patients should have an adequate fasting period to improve the chances of an empty stomach. Gastrokinetic medications such as metoclopramide have been thought to be of benefit because they enhance gastric emptying, but no good data support this belief. It is helpful to increase gastric pH by either nonparticulate antacids such as sodium citrate or histamine-receptor (H2) antagonists, which decrease acid production. The market now includes several H2

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