What a Long, Strange Trip it's Been....Anesthesia & Sedation

The word anesthesia tends to induce a feeling of apprehension in many of us. You may have heard or read about a pet that experienced an adverse effect with anesthesia. However, anesthesia in veterinary medicine has come a long ways in the past 10-20 years, and we’d like to address some of the questions and concerns surrounding the matter.  

Just what IS anesthesia?  

According to Merriam-Webster, anesthesia is the “loss of sensation, with or without loss of consciousness;” though most of us think of the loss of consciousness associated with general anesthesia when we think of the word anesthesia. General anesthesia refers to anesthesia of the whole body, and typically infers a loss of consciousness.  General anesthesia is often induced with injectable drugs, and maintained with inhaled gases. Local anesthesia refers to anesthesia that only affects an area of the body, and may or may not be associated with a loss of consciousness. Local anesthesia, aka a “nerve block” is given as an injection (or in some cases may be applied topically directly to the skin) directly around the area that will be subject to pain.  

Are sedation and anesthesia the same thing?

No, typically not.  Sedation refers to inducing a state where the patient is calm/relaxed and may or may not be conscious. Sedation may be used to help reduce anxiety and pain and facilitate minor procedures (such as x-rays or bandage changes, etc…) in a patient that is painful, fearful or otherwise difficult to handle.  

What are the risks of anesthesia?

In the vast majority of cases, any risks of anesthesia are more closely associated with the procedure itself or with the animal’s underlying disease, than with the drugs themselves.  Hypotension, or low blood pressure, and respiratory depression (decreased breathing) are two of the main side effects of many anesthetic protocols.  Fortunately, with diligent monitoring of the patient while under anesthesia, these side effects can be effectively minimized or controlled.  

Very rarely, an idiosyncratic or unpredictable reaction to one of the anesthesia drugs may occur.  By its very nature, this cannot be predicted or prepared for ahead of time.  Careful monitoring of the patient under anesthesia and the use of short-acting or reversible drugs may help mitigate risks associated with this.    

Less serious risks include vomiting or nausea following anesthesia, or prolonged sedation; but even these risks and side effects can often be managed with anti-nausea support and choosing a drug protocol that takes into careful consideration a patient’s health and metabolic status.  

What can be done to minimize risks associated with anesthesia?

• Knowing the pet’s history – Any previous anesthesia? How did the patient handle the drugs used? Any adverse effects? Any breed sensitivities? etc… can help the veterinarian select the best individualized anesthetic protocol. If you have any records detailing previous anesthesia, or know that your pet previously did not respond well to a specific medication, it is important to share this information with your veterinarian.

• A thorough physical exam, with emphasis on cardiac and respiratory status, conducted ahead of time can help to identify any conditions that may compromise the patient during anesthesia or make them more sensitive to certain drugs

• Preoperative blood work helps to assess for underlying metabolic issues that may affect how the patient responds to drugs used during anesthesia or associated with the procedure

• Multimodal anesthesia — this refers to the practice of using multiple drugs in conjunction, rather than a single agent, allowing lower doses of each drug to be used, thereby minimizing side effects of each individual drug. For a typical surgical procedure, the patient receives a cocktail of “premedication” – often an opioid-type pain reliever in conjunction with a sedative type of drug. This allows lower doses of the drugs used to induce anesthesia and gas anesthesia to be used during the procedure

• Careful monitoring during and after anesthesia — at many practices in our area, veterinary patients are monitored with much of the same equipment as you and I if we were under anesthesia – blood pressure, oxygen saturation, respiration, heart rate, expired CO2, and EKG; in addition to machines measuring vital signs, having a dedicated and trained technician monitoring anesthesia is vitally important in minimizing adverse effects of anesthesia, as they are trained to catch an issue such as dropping blood pressure or slowing heart rate before it causes a problem.

How long will it take my pet to recover from anesthesia?

The patient is very carefully monitored while waking up from anesthesia and in the immediate period post-operatively.  Depending on the drugs used and the health of the patient, the full effects of sedation and anesthesia generally take about 24 hours to be gone, but can take 48-72 hours. Prolonged recovery from a sedation or anesthetic event is something your veterinarian should note so that either other drugs or doses can be used in the future (if needed).

Additional pet-parent resources can be found at the American Veterinary Medical Association’s website and the American College of Veterinary Anesthesia & Analgesia’swebsite.