Treatments for Acid Reflux During Anesthesia: Preventing Aspiration Pneumonia
Acid reflux bothers most people at some point in their lives. For some, it is an occasional annoyance associated with certain food and drinks or the overindulgence in them.
Other people can be quite debilitated by the symptoms and may be found to have ulcers of the esophagus or stomach, or a hiatal hernia.
Why Does Acid Reflux Matter during Anesthesia?
During anesthesia, acid can reflux from the stomach, into the esophagus. From the esophagus, the acid can enter the back of the throat and be aspirated into the lungs. This can cause damage to the lungs, infections and problems with oxygen levels. Aspiration pneumonia means that something has been inhaled to the lungs that doesn't belong there (acid, in this case) and caused damage to the lungs. Aspiration pneumonia is a serious consequence of acid reflux under anesthesia if the acid reaches the lungs.
That's the brief explanation. Let's look more closely at the problem and potential solutions.
What is Acid Reflux?
Because several terms are used interchangeably, discussions of acid reflux and GERD - gastroesophageal reflux disease, can become confusing. For most intents and purposes, it doesn't much matter that the terms may be used as if they are the same things, even though there are differences.
Just for clarity, though, here are the phrases you may hear in when dealing with reflux or GERD. The esophagus is the "foodpipe" leading from the mouth to the stomach. The prefix gastro- means stomach. So, "gastroesophageal" means stomach and esophagus.
- Heartburn is the feeling (the symptom) of pain or burning that occurs when there is too much acid in the stomach or when that acid refluxes into the esophagus.
- Acid Reflux refers to the physiologic process of acid backing up into the esophagus from the stomach.
- GER stands for gastroesophageal reflux. This is the same as acid reflux, although food or liquids may also reflux into the esophagus and even up into the throat.
- GERD means gastroesophageal reflux disease. This is a more serious disorder that results from ongoing acid reflux. GERD may be associated with stomach ulcer, narrowing of the esophagus and is a risk factor for esophageal cancer.
How Does Acid Reflux Happen?
This video provides an excellent explanation of heartburn, reflux and GERD.
What are the Dangers of Acid Reflux during Anesthesia?
Normally the lower esophageal sphincter (the muscular ring between the stomach and esophagus) works to keep stomach acid from backing up into the esophagus. As discussed in the video, acid reflux results when the lower esophageal sphincter doesn't function properly.
Normally, if acid refluxes all the way up to the back of the throat, several protective airway reflexes keep the acid from then traveling down the trachea (windpipe) to the lungs. Closure of the vocal cords, coughing and gagging are examples of these protective reflexes.
Under anesthesia, several things happen that make gastroesophageal reflux a danger.
- The lower esophageal sphincter relaxes even more, making it more likely that acid will reflux and could get into the lungs.
- The upper esophageal sphincter (at the top of the esophagus) also relaxes, allowing acid to enter the pharynx (back of the throat).
- Stomach emptying is impaired and acid volume can increase, making reflux more likely -- and more dangerous when it does occur.
- Airway reflexes are suppressed and the unconscious patient is unable to protect the lungs. This increases the likelihood of "aspiration pneumonia"
What Can You Do to Prevent Problems with Acid Reflux during an Anesthetic?
- If you have symptoms, get an evaluation and treatment prior to surgery.
- Follow fasting instructions as to when to stop eating and drinking before surgery.
- Take medications at home as directed.
- Avoid trigger foods and drinks the night before surgery.
- Quit smoking well in advance of your surgery (8 weeks seems optimal).
- Make sure your anesthesiologist is aware if you have severe symptoms.
How Do Anesthesiologists Prevent Acid Reflux during Anesthesia
We know that acid reflux can cause aspiration pneumonia, which can sometimes result in serious damage to the lungs. So, as anesthesiologists, our goal is to prevent acid reflux as much as possible, in order to prevent aspiration pneumonia.
Our prevention regimen is also designed to minimize the damage done, if aspiration should occur. We know that the extent of damage is influenced by two main variables.
- Amount of aspirate: The higher the volume of stomach fluid aspirated, the more damage that will occur. It seems that anything more than 20-25ml (30ml=1oz), increases the risk of serious damage.
- Acidity: The more acidic (the lower the pH) the fluid that enters the lungs, the more harmful it is to the lung tissue.
So, the anesthesia plan will seek to minimize these two risks, in addition to preventing acid reflux and aspiration pneumonia in the first place. Medications and special adjustments of airway management during unconsciousness are used to this end.
To reduce the volume in the stomach that can potentially be aspirated, you will be asked to fast for a period of time before surgery. The anesthesiologist may put a medicine in your IV that helps the stomach empty properly (metoclopromide or Reglan) during and after anesthesia. This helps with nausea afterwards, too.
To increase the pH (make the fluid less acidic), the anesthesiologist may use IV acid-blockers. Common medications like famotidine (Pepcid) and ranitidine (Zantac) are available IV. There is also a liquid that you may be asked to drink called bicitra that changes the pH of the stomach fluid.
Airway Management in High-risk Patients
Anesthesia providers will also seek to prevent any refluxed acid from ever reaching the throat by providing a physical barrier to aspiration.
Oxygen and gas anesthesia can be delivered via a number of devices during general anesthesia. Masks (on the face or laryngeal mask airways --LMAs-- that go in the back of the throat) do not block the trachea, and therefore do not protect from aspiration. Endotracheal tubes do provide this protection and are therefore, the airway device of choice for patients who have frequent or severe reflux or GERD.
What Does the Anesthesiologist Do to Prevent Aspiration?
As you 'go to sleep' for your anesthetic, your airway reflexes disappear. This is a high-risk time for aspiration. To prevent this, your anesthesiologist will have an assistant put pressure on the front of your neck by pushing down on the cricoid cartilage near the Adam's apple. This ring of cartilage is part of the windpipe, which is in front of the esophagus. By pushing on this rigid structure, pressure is transmitted backwards, compressing the esophagus. Any acid is prevented from rising all the way up to the throat. This is called the Sellick maneuver.
In addition, your anesthesiologist will place the breathing tube quickly. The breathing tube goes between the vocal cords and extends a short way into the trachea. Circling the outside of the breathing tube is a balloon--shown in the bottom photo-- that can be inflated. This cuff on the breathing tube prevents any acid that reaches the back of the throat from entering the windpipe.
At the end of the operation, the breathing tube will not be removed until airway reflexes (swallowing, coughing, etc) have returned. Usually, people are conscious, but not really 'awake' or aware when it is removed and few people have any memory of that event.
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