Pulmonary aspiration can cause significant morbidity and mortality to affected patients. It is the anesthesiologist’s responsibility to assess a patient’s risk for aspiration and determine the best anesthetic plan for the patient to minimize the occurrence and severity of pulmonary aspiration. The anesthesiologist should control gastric contents by minimizing intake of the patient and observing the nil per os (NPO) guidelines. When indicated, enhancing gastric emptying and decreasing volume, and increasing pH of gastric contents should also be incorporated into the anesthetic plan. In addition, rapid sequence induction and intubation should also be considered in the anesthetic plan for those with a full stomach status.
Before administering any anesthetic, the anesthesiologist should determine the NPO status. One key method to control gastric contents is to minimize intake by following the American Society of Anesthesiologists’ (ASA) preoperative fasting practice guidelines (Table 67-1).
TABLE 67-1NPO Guidelines ||Download (.pdf) TABLE 67-1 NPO Guidelines
|Clear liquids ||2 h |
|Breast milk ||4 h |
|Infant formula ||6 h |
|Nonhuman milk ||6 h |
|Light meal ||6 h |
|Full meal ||8 h |
It is acceptable to ingest clear liquids at least 2 hours before an elective procedure under monitored anesthesia care, regional anesthesia, or general anesthesia. Examples of clear liquids are water, carbonated beverages, juices without pulp, clear tea, and black coffee. Alcohol is not included as an acceptable clear liquid. The amount of liquid consumed is not as significant as the type of liquid consumed.
It is acceptable to ingest breast milk at least 4 hours before an elective procedure under monitored anesthesia care, regional anesthesia, or general anesthesia.
It is acceptable to ingest infant formula at least 6 hours before elective procedures under monitored anesthesia care, regional anesthesia, or general anesthesia.
It is acceptable to ingest nonhuman milk or a light meal 6 hours before elective surgery under monitored anesthesia care, regional anesthesia, or general anesthesia. Consuming meat or foods high in fat content can delay gastric emptying. Extra fasting time, typically 8 hours or more, may be necessary. The total amount and kind of food consumed must be taken into account when deciding an acceptable fasting period. Because nonhuman milk is comparable to solids in gastric emptying time, one must consider the amount ingested to decide on an appropriate fasting period.
Other Methods to Control Gastric Contents
In certain situations, following NPO guidelines may not be feasible. In emergency cases, such as trauma, surgery cannot be delayed by the recommended time to allow for full gastric emptying. Or even if guidelines are followed, ...