Why Can't I Eat or Drink Before My Surgery?

To ensure your safety while under anesthesia.

Ever been eating and have something go "down the wrong way"? You probably coughed and gasped, and teared up and struggled for breath, until the offending material was coughed back up and cleared from your windpipe. This vigorous response by your body is due to airway reflexes whose sole purpose in life is to keep foreign material out of your air passages. Without these airway reflexes, nasty stuff would continually contaminate our air passages, leading to serious complications, even death. This mishap is known as aspiration.

One of the effects of anesthesia is that these airway reflexes are suppressed so that they no longer function properly. This occurs with almost every general anesthetic and can also occur with heavy sedation short of complete unconsciousness. Under these circumstances, any material that happened to be in the stomach could make its way up the swallowing tube (esophagus) in a recumbent patient, and into the mouth, from where it is a straight shot into the windpipe (trachea) and into the lungs themselves. Stomach contents are often highly acidic particles of partially digested food, and this is just about the worst thing one can aspirate into the lungs. Aspiration used to be one of the most frequent and feared complications of anesthesia. Now it is a rarity thanks to diligent attention to proper "nothing by mouth" (NPO) procedures.

For this reason we strictly enforce rules determining the consumption of food and drink prior to surgery, so that the stomach is as empty as possible at the time of anesthetic induction. How long a period of time is required for complete emptying of the stomach varies from patient to patient and includes such factors as age, sex, pregnancy, obesity, medications, and underlying medical condition. Often we must make an informed judgement about when it is safe to proceed. In doing so we take into account all of the above factors, and consider the urgency of the surgery.

For most strictly elective procedures we generally require eight hours since the last consumption of solid food before anesthesia can be induced. Liquids containing protein, fat, or particles, such as milk or coffee creamer, are considered solids for the purposes of this requirement.

Clear liquids, loosely defined as a liquid you can "read the newspaper through" can be consumed up to four hours before surgery. Examples of clear liquids include water, black coffee or tea, clear sodas, or fruit juices without pulp or solids. Soup or broth are considered solid foods because of the presence of suspended solids and fat, which slows stomach emptying.

Furthermore, we treat ANY amount of solid-food consumption the same as if you have eaten an entire Thanksgiving dinner. We do so because experience has shown us that patients often underestimate how much they have eaten, and we prefer to err on the side of safety when such a serious matter is at hand.

For emergency, life-saving surgery, without which the patient can be expected to suffer imminent injury or death, the risks of delaying surgery to allow the stomach to clear outweigh the risk of proceeding with a potentially full stomach. In these cases we take precautions to lessen the risk of aspiration and to decrease the chances that, should aspiration occur, any injury should result from it. The determination of what constitutes an emergency is a judgment that will be made jointly by your surgeon and your anesthesiologist.

For those procedures that are urgent but not emergent--which need to be done soon but which can wait long enough to empty the stomach--we generally enforce the NPO rules outlined above.

What drugs will I get with general anesthesia?

General anesthesia involves the use of multiple different medications that are chosen on a case-by-case basis by the anesthesiologists. Decisions are made based on the patient characteristics, and on the length and type of surgical procedure. The majority of the time, adults receive an intravenous induction agent, such as a short-acting barbiturate or sedative-hypnotic (usually propofol). Maintenance of anesthesia is usually with a combination of inhalational anesthetic agents (i.e., gases), opioid narcotics, muscle relaxants and sedative hypnotic medications.

What are the risks and side effects of anesthesia?

Like any medical procedure or drug, anesthetic drugs and techniques come with potential side effects and risks, apart from the risks of the operation itself. Some of these risks are quite serious or even potentially fatal. Fortunately the more serious risks are extremely rare. You are far safer statistically during the time you are under anesthesia than if you spent that same period of time driving your car.

This listing is not meant to be all-inclusive, so you must discuss this subject with your anesthesiologist prior to your surgery. He or she can better inform you of the
risks and side effects that are pertinent to the planned anesthetic for YOU.

General Anesthesia

• Injury to mouth, lips, teeth, dental work, and other airway structures during placement of airway-management devices
• Injury to eyes, ears, limbs, nerves, or genitals from positioning or pressure
• Injury to eyes from contact with hands or equipment, or from dryness under anesthesia
• Heart attack or stroke
• Allergic reaction or adverse reaction to anesthetic drugs, fortunately very rare
• Nausea with or without vomiting
• Aspiration of stomach contents, leading to injury or death
• Death: extremely remote but finite chance
  

Regional Anesthesia

• Failure of the block to properly work. For various reasons sometimes blocks do not work as planned. This will be determined BEFORE surgery begins and alternate anesthetic methods will be used
• Injury to nerves blocked
• Fluctuations in blood pressure or pulse (spinal or epidural anesthetics), inconsequential for most patients
• Injury to the spinal cord or spinal nerves, resulting in partial or complete paralysis
• Unexpected spread of spinal or epidural anesthetics, requiring life support while the drugs wear off
• Inadvertent injection of local anesthetics into the bloodstream, causing seizures or heart rhythm problems, potentially fatal
• Itching, drowsiness, respiratory depression, or temporary bladder or bowel impairment from narcotics administered via the spinal or epidural route
• Death: extremely remote but finite chance

How will you know if I am really asleep?

Awareness or recall under anesthesia is a very disturbing and frightening event, one which we strive to prevent. Fortunately, it is also a rare event and tends to happen under certain special circumstances, which we try to anticipate and prevent wherever possible. These circumstances usually have to do with an extremely ill patient who cannot tolerate the usual doses of anesthetic drugs which provide amnesia and unconsciousness. We are generally able to anticipate when this is the case and to take measures to provide amnesia and/or hypnosis.

We encourage you to discuss your concerns about this important topic with your anesthesiologist.

Types of Anesthesia