title: [The recent trend in preoperative fasting].
abstract: It has been generally practiced that patients are restrained from any foods and water 4-6 hr prior to anesthesia. Recent trends of anesthesiologist, however, are to permit the patients to take fluid until 2-3 hr before inducing anesthesia, as described in the guidelines from Canadian Anaesthetists' Society in 1990, and in the authoritative textbooks of anesthesia. We compared effects of the preoperative fasting between age-matched groups of patients constrained to: 1) 6 hr absolute preoperative fasting, and 2) 6 hr fasting but free for taking clear fluid until 2 hr before operation. Residual gastric volume and pH immediately after inducing anesthesia were monitored. In the respective age groups from infant to the aged, no significant changes were observed between 1) and 2). Considering that light meal leaves the stomach in 1.5-3 hr and clear fluid almost immediately, these results accurately explain and support relevance of the current concept concerning the preoperative fasting. Furthermore, since actual incidence of aspiration pneumonia during anesthesia is sufficiently low, strict preoperative fasting may be unreasonable. We consider that reducing the fasting time may not increase the risk of pulmonary aspiration and recommend our practical method consisting of preoperative 6 hr withholding solid foods while allowing clear fluid ingestion until 2-3 hr before inducing anesthesia.
mesh_terms: D005215:Fasting; D005750:Gastric Juice / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011015:Pneumonia, Aspiration / Q000517:prevention & control; D011300:Preoperative Care; D013997:Time Factors; D014868:Water Deprivation