Nothing by mouth is a 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 branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
phrase that translates to English as "nothing through the mouth". Variants include nil by mouth (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 inc ...
, e.g. in those who will undergo
general anesthesia
General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...
, or those with weak swallowing musculature, or in case of
gastrointestinal bleeding
Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include ...
,
gastrointestinal blockage, or
acute pancreatitis
Acute pancreatitis (AP) is a sudden inflammation of the pancreas. Causes in order of frequency include: 1) a gallstone impacted in the common bile duct beyond the point where the pancreatic duct joins it; 2) heavy alcohol use; 3) systemic disea ...
. 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
The American Board of Anesthesiology sets standards and exams for the accreditation of Board certified anesthesiologists coming to the end of their residency. It is one of the 24 medical specialty boards that constitutes the American Board of M ...
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.
For extended periods without food or water, patients may be started on
total parenteral nutrition (TPN).
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
Torbay Hospital is the main hospital of South Devon, England. It is managed by the Torbay and South Devon NHS Foundation Trust.
History
The hospital was founded as the Torbay Hospital, Provident Dispensary and Eye Infirmary in 1844.
Constructi ...
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
__NOTOC__
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)''
The list also is divided alphabetically into twenty page ...
*
Per os
Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are ...
*
Preoperative fasting
Preoperative fasting is the practice of a surgical patient abstaining from eating or drinking (" nothing by mouth") for some time before having an operation. This is intended to prevent stomach contents from getting into the windpipe and lungs (kno ...
References
{{DEFAULTSORT:Nil Per Os
Medical terminology
Latin medical words and phrases