NPO, or nil per os, is a medical directive signifying that a patient is to receive “nothing by mouth.” This instruction is frequently misunderstood, especially regarding modern nutritional support methods like tube feeding. The confusion lies in whether this restriction on oral intake also applies to a tube that bypasses the mouth entirely. Clarifying the clinical distinction between a simple oral restriction and a comprehensive gastrointestinal restriction is necessary for patient safety and proper care.
Defining NPO (Nil Per Os)
NPO is a standard medical order instructing a patient to abstain from all substances that pass through the oral cavity. This includes not only solid foods but also liquids, chewing gum, and sometimes even medications, unless specifically noted otherwise by a physician.
The primary reason for a standard NPO order relates directly to patient safety during procedures requiring anesthesia or sedation. When a patient is sedated, the protective airway reflexes, such as the gag and cough reflexes, are temporarily suppressed. If there is food or liquid in the stomach, this suppression increases the risk of the stomach contents being regurgitated and entering the lungs, a complication known as pulmonary aspiration.
Pulmonary aspiration can lead to severe health issues, including aspiration pneumonia. The fasting period is designed to allow the stomach to empty its contents completely, reducing the volume of material available to be aspirated. For this reason, standard NPO orders are strictly enforced before surgeries and certain diagnostic procedures like endoscopies.
Understanding Enteral Tube Feeding
Enteral nutrition, commonly known as tube feeding, is a method of delivering liquid nutrition and hydration directly into the gastrointestinal (GI) tract. This method is utilized when a patient’s GI tract is still functional, but oral intake is impossible, unsafe, or insufficient to meet their nutritional needs. Common reasons include difficulty swallowing due to a stroke, head or neck cancer, or critical illness.
The delivery route for enteral feeding bypasses the mouth and pharynx, distinguishing it from normal eating. Tubes can be placed through the nose, such as a nasogastric (NG) tube that ends in the stomach, or surgically placed directly into the abdomen. Tubes inserted through the abdominal wall include a gastrostomy (G-tube) that enters the stomach, or a jejunostomy (J-tube) that enters the small intestine.
The purpose of tube feeding is to maintain or improve a patient’s nutritional status while avoiding the risks associated with oral intake, such as aspiration. Because the formula is delivered directly to the stomach or small intestine, the intervention is designed to keep the digestive system working.
When NPO Orders Restrict Tube Feeding
The literal translation of NPO, meaning “nothing by mouth,” suggests that tube feeding, which bypasses the mouth, should be permitted. In clinical practice, however, the answer depends entirely on the specific reason the NPO order was issued. A standard NPO order for surgery pre-procedure often means tube feeding is restricted only if the tube terminates in the stomach.
When a patient has a nasogastric or gastrostomy tube, the stomach is still the primary site of delivery, and the liquid feeds are treated similarly to solid food intake. For procedures involving general anesthesia, gastric tube feeds are typically held for about six hours before the procedure, mirroring the standard fasting guidelines for solids. This is necessary because the stomach contents, regardless of their entry point, still pose an aspiration risk during intubation.
However, if the tube terminates past the stomach, in the small intestine, it is considered post-pyloric feeding. The feeds are often continued until the patient is transported to the operating room. Since the formula is delivered directly into the small intestine, it significantly reduces the volume of material that could be regurgitated from the stomach.
In other scenarios, a physician may order a comprehensive gastrointestinal rest, which explicitly includes the restriction of enteral feeds. This type of order, often written as “NPO, including enteral feeds,” is common for conditions like severe pancreatitis, acute gastrointestinal bleeding, or bowel obstruction. For these specific medical issues, the goal is to stop all mechanical and chemical stimulation of the digestive tract to promote healing and reduce symptoms.