Nothing by mouth is an American medical instruction meaning to withhold food and fluids. It is also known as nil per os (npo or NPO), a
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
phrase that translates to English as "nothing through the mouth". Nil by mouth is the term used in the UK (NBM), nihil/non/nulla per os, or complete bowel rest. A liquid-only diet may also be referred to as bowel rest.
''NPO'' is one of the abbreviations that is not used in
AMA style; "nothing by mouth" is spelled out instead.
Purpose
The typical reason for NPO instructions is the prevention of
aspiration pneumonia
Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complications may incl ...
, e.g. in those who will undergo
general anesthesia
General anaesthesia (UK) or general anesthesia (US) is medically induced loss of consciousness that renders a patient unarousable even by painful stimuli. It is achieved through medications, which can be injected or inhaled, often with an analgesi ...
, or those with weak swallowing musculature, or in case of
gastrointestinal bleeding,
gastrointestinal blockage, or
acute pancreatitis. Alcohol overdoses that result in vomiting or severe external bleeding also warrant NPO instructions for a period.
Duration
Pre-surgery NPO orders are typically between 6 and 12 hours prior to surgery, through recovery suite discharge, but may be longer if long acting medications or oral post-meds were administered. It is not uncommon for the food NPO period to be longer than that for liquid, as the
American Board of Anesthesiology advises against liquid NPO periods greater than eight hours. The NPO periods for illness tend to be much longer, although exceptions are made for small scheduled amounts of water consumption if an IV drip is not in use. With sufficient IV fluids, NPO periods of several days have been utilized successfully in non-diabetic patients (although short NPO periods in diabetics are possible with IV fluids, insulin, and dextrose. Extended periods (greater than 12 hours) are still contraindicated).
The American Board of Anesthesiology recommends that patients should not eat solid food for at least 8 hours prior to a procedure, and should not drink even clear liquids for at least 2 hours prior. Clear liquid fasting includes water, juices without pulp, carbonated beverages, clear tea, and black coffee.
[Levy, DM. Pre-operative fasting – 60 years on from Mendelson. Contin Educ Anaesth Crit Care Pain (2006) 6 (6): 215-218] Ingestion of water 2 hours prior to a procedure results in smaller gastric volumes and higher gastric pH when compared with those who ingested > 4 hours prior. The volume of liquid is less important than the type of liquid ingested.
Non-emergency surgical cases should be delayed for NPO status.
When nothing by mouth or a liquid-only diet is indicated for an extended period,
enteral feeding
A feeding tube is a medical device used to provide nutrition to people who cannot obtain nutrition by mouth, are unable to swallow safely, or need nutritional supplementation. The state of being fed by a feeding tube is called gavage, enteral fee ...
or
total parenteral nutrition
Parenteral nutrition (PN), or intravenous feeding, is the feeding of nutritional products to a person intravenously, bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding entities or standard pha ...
may be recommended.
Unrestricted clear fluids
Fasting guidelines often restrict the intake of any oral fluid after two to six hours preoperatively. However, it has been demonstrated in a large retrospective analysis in
Torbay Hospital that unrestricted clear oral fluids right up until transfer to theatre could significantly reduce the incidence of postoperative nausea and vomiting without an increased risk in the adverse outcomes for which such conservative guidance exists.
See also
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List of abbreviations used in medical prescriptions
This is a list of abbreviations used in medical prescriptions, including hospital orders (the patient-directed part of which is referred to as sig codes). This list does not include abbreviations for pharmaceuticals or drug name suffixes such as C ...
*
List of Latin phrases
This is a list of Wikipedia articles of Latin phrases and their translation into English.
To view all phrases on a single, lengthy document, see: List of Latin phrases (full).
Lists of pages
* List of Latin phrases (A)
* List of Latin phrases ( ...
*
Per os
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Preoperative fasting
References
{{DEFAULTSORT:Nil Per Os
Medical terminology
Latin medical words and phrases