Medical abbreviations are a common shorthand in healthcare, but they can be confusing for patients. The abbreviation NPO is frequently given as a patient instruction before certain medical procedures or tests. This safety directive means “Nothing By Mouth,” and strict adherence to this order is necessary to prevent potential medical complications.
Defining Nil Per Os
The medical abbreviation NPO comes from the Latin phrase Nil Per Os. Translating literally, this means “nothing through the mouth,” which clearly defines the instruction given to the patient. This standardized instruction is recognized globally in clinical settings, ensuring a clear and consistent communication of the fasting requirement. When a healthcare provider orders NPO status, it establishes a specific period during which a patient must abstain from taking anything orally until the order is lifted.
Medical Necessity of NPO Status
The primary reason for implementing NPO status relates to patient safety during procedures requiring sedation or general anesthesia. Anesthesia temporarily suppresses the body’s protective reflexes, including the gag reflex and the ability to swallow effectively. If the stomach contains food or liquid when these reflexes are compromised, the contents may be regurgitated into the back of the throat. This can lead to pulmonary aspiration, which occurs when stomach contents are inhaled into the lungs. Gastric contents are highly acidic and can cause aspiration pneumonitis, which may progress to aspiration pneumonia, respiratory failure, or acute respiratory distress syndrome. By ensuring the stomach is empty before the procedure, the volume and acidity of any potential aspirate are significantly reduced, minimizing this risk.
NPO status is also necessary for certain diagnostic tests to ensure accurate results. Tests that examine the gastrointestinal tract, such as endoscopies or colonoscopies, require a clear and unobstructed view, which is only possible with an empty stomach and bowel. Additionally, some blood tests, like those measuring blood glucose or lipids, require fasting to provide a reliable baseline measurement uninfluenced by recent digestion.
Practical Rules Patients Must Follow
The instruction “Nothing By Mouth” is comprehensive and applies to all forms of oral intake, not just solid foods. Patients must abstain from all liquids, including water, clear juices without pulp, coffee, and tea, during the designated NPO period. Even small amounts of water can increase the volume in the stomach, which is why the instruction is so strict.
The rule also extends to items that stimulate saliva or gastric secretions, such as chewing gum, hard candies, and lozenges, which must be avoided. Smoking and the use of tobacco products are also restricted, as nicotine can increase stomach acid production and slow down gastric emptying. Failure to adhere to the NPO order, even consuming a small amount of liquid, can result in the postponement or cancellation of the scheduled procedure for safety reasons.
The common exception to the strict NPO rule is for certain necessary oral medications. Medications for conditions like high blood pressure or heart problems may be permitted by the healthcare provider, often with a minimal sip of water. Patients must always confirm which medications they should take and precisely when they can take them with their physician or anesthesiologist.