Table 4 Risk factors for aspiration (Zargar-Shoshtari et al. 2009)

Patient factors

(a) Full stomach

 · Emergency surgery

 · Inadequate fasting time

 · Gastrointestinal obstruction

(b) Delayed gastric emptying

 · Systemic diseases, i.e., diabetes mellitus, chronic kidney disease

 · Recent trauma

 · Opioids

 · Raised intracranial pressure

 · Previous gastrointestinal surgery

 · Pregnancy (including active labor)

(c) Incompetent lower esophageal sphincter

 · Hiatus hernia

 · Recurrent regurgitation

 · Dyspepsia

 · Previous upper gastrointestinal surgery

 · Pregnancy

(d) Esophageal diseases

 · Previous gastrointestinal surgery

 · Morbid obesity

Surgical factors

Upper gastrointestinal surgery

 · Lithotomy or head down position

 · Laparoscopy

 · Cholecystectomy

Anesthetic factors

Light anesthesia

 · Supraglottic airways

 · Positive pressure ventilation

 · Length of surgery >2 h

 · Difficult airway

Device factors

First-generation supraglottic airway devices