Anesthesia and Asthma
Risks of Asthma and General Anesthesia
Overall, general (and other types of) anesthesia are very, very safe. The risks of anesthesia are often related to preexisting health problems. As an MD anesthesiologist, I can attest to the fact that, most of the time, even people with significant health issues can be safely anesthetized and awakened with the proper preparation.
Asthma and general anesthesia both affect breathing, so it's no surprise that there are issues that need to be addressed before, during and after an anesthetic. Asthmatics do have increased risk of some postoperative complications, but for most people, these can be minimized with careful evaluation, prevention and treatment of asthma symptoms.
Anesthesia Preoperative Evaluation: Asthma
Asthma is described as a chronic medical condition where the small airways in the lungs -- the bronchi -- swell and constrict. This causes a subjective feeling of shortness of breath and the objective finding of decreased or turbulent air movement heard as wheezing.
During your preoperative evaluation, you will be asked a series of questions about your health involving various body and organ systems. If you have asthma, you will be questioned about the severity and any medications you use to control it.
- Do you have asthma?
- How severe is it now?
- How long have you had it?
- Do you take any medications for it?
- Are you having any symptoms now?
- What are your usual triggers for an attack?
- Have you ever gone to the ER with asthma?
- Have you ever been in the ICU for asthma?
- Have you had pulmonary function tests to assess your asthma?
- Have you ever had to have a breathing tube placed for asthma?
If you answer yes to any questions that indicate your asthma is severe, you will be asked more specific questions about your symptoms, testing and treatment.
Schematic of Airway during Asthma Attack
Leading up to your surgery...
Use inhalers as usual or as instructed
Take other medications as prescribed
See your doctor if you haven't had a recent checkup for your asthma (or any other medical problems)
Tell your doctor (surgeon/anesthesiologist) about any symptoms you are having or illnesses in the 2 weeks before surgery
Preoperative Preparations if You Have Asthma
If you have mild asthma, you will likely be instructed to use your "as-needed" inhaler on the morning of surgery. You may also be asked to bring this inhaler to the hospital or surgery center with you.
If your asthma is more severe, you will be instructed to use your inhalers as usual. If you take any oral medications, you will most likely take those on schedule, too. If you take steroids on a chronic basis (orally) for asthma, you may need more workup and optimization before elective surgery. Severe asthmatics require pulmonary function tests and/or a note from your pulmonologist (lung specialist) regarding the ideal management of your obstructive airway disease.
Abnormal Lung Sounds: Ever wonder what your doctor is listening for in your lungs?
Preventing Asthma during Anesthesia: What Your Anesthesiologist Does.
In addition to the very important preventative steps you take, your anesthesiologist is specifically trained to handle asthma-related issues during and after surgery.
Your anesthesiologist will listen to your lungs before you go to sleep to identify any wheezing or other abnormal breath sounds. Your oxygen level will be measured with a lighted finger clip and he or she will review any test results.
You may be asked to take puffs of your inhalers on the morning of surgery, if you had not already done so.
If possible, your anesthesiologist may try to avoid placing a breathing tube. The breathing tube goes between the vocal cords into the windpipe. Because it is IN the airway, the breathing tube can be irritating and trigger airway constriction and an asthma attack. Very often a breathing tube is mandatory for the type of surgery you are having.
A device called a laryngeal mask airway (LMA) sits in the back of the throat and overlies the airway instead of being placed in it. This causes a bit less airway irritation and may less likely to cause bronchospasm and airway constriction. There are many limitations to use of an LMA, so if your anesthesiologist doesn't use one, there is probably a good reason.
During your anesthetic, your anesthesiologist monitors your oxygen level. The little lighted clip placed on your finger is able to measure the percent of oxygen saturation of your red blood cells in your arterial pulse.
Also, your breathing is monitored while you are anesthetized. During surgery, a ventilator may help you breathe. At the end of surgery, before waking up, you will resume breathing on your own. While the ventilator is being used, the anesthesiologist can get a measurement of your airway pressures. This value will be increased above normal values if your airways are constricted. There are other parameters that can give the anesthesiologist important information about your lungs and breathing, as well.
The rate and depth of your own breathing is assessed as you wake up. The anesthesia provider will listen to your lungs to assess for wheezing or other problems if he or she has any concerns about your asthma.
DURING AND AFTER:
If there is any problem with asthma during anesthesia, medications can be given while you are still sleeping. Usually, if there is any issue at all, it is often minor and easily treated with some albuterol sprayed down the breathing tube or some steroids given in your IV.
If you still have any wheezing or signs of constricted airways when you wake up, you can be given a nebulized breathing treatment in the recovery room.
Rarely, in severe asthmatics, it is not possible to remove the breathing tube right at the end of surgery. If the oxygen level is too low or the airway pressure is too high, you can be kept heavily sedated and the breathing tube can be left in for a while to allow more intensive treatment in the ICU.
Are you using your inhaler properly? Are you sure?
Those at risk for more significant problems with asthma after surgery are
- Severe asthmatics
- Those whose asthma is not under good control at the time of surgery
- Asthmatics who smoke
- Asthmatics with recent respiratory infections
- Asthmatics presenting for airway surgery
- Asthmatics presenting for emergency surgery (with less-than-ideal control of asthma)
Who is at Risk of Asthma Complications after Surgery?
For most people with mild to moderate asthma, the risks of anesthesia are minor and not excessive. In other words, even if your lungs do become reactive, it is usually easily treated, sometimes while you are still asleep. The degree of bronchospasm is not severe and doesn't cause concerning drops in the oxygen level or increases in airway pressure on the monitor.
As expected, people with more severe asthma or asthma that is not well-controlled going into surgery are more likely to have problems with reactive airways during and after surgery.
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Asthma in America: Ten States with the Highest Prevalence of Adult Asthma (percent of population listed below)
Prevalence data compiled from statistics of the Centers for Disease Control in the US - 2010 http://www.cdc.gov/asthma/brfss/2010/lifetime/tableL1.htm))
Although, Hawaii (maybe surprisingly) has the highest self-reported asthma rate, the Northeast United States is highly represented in the top ten.