The patient says he is “not sensitive to anesthetics”, what should I do?

The first surgery today was an arthroscopic meniscus repair. When I explained the anesthesia risks and signed the patient's consent form, he became very anxious.

"Doctor, I want to choose half-body anesthesia, but I'm afraid of pain. Because during the last operation, I was "resistant to anesthesia" and endured the operation."

"What surgery?" When I heard this new term, I was very confused!

"When I gave birth, I had to have a cesarean section. And when I had a tooth pulled last time, the anesthesia didn't work. Please give me more anesthesia, I'm afraid of the pain!"

"Don't give me too much anesthetic. Too much may cause poisoning. It's okay. I will definitely not let you feel any pain."

"Give me more. I saw online that I could give you some antagonists at the end."

In the past, when I encountered this situation, I would explain to the patient that it might be because he was too anxious and nervous. So what is the truth behind the common saying of patients, "I am not sensitive to anesthetics"? Today, let's find out the reason behind this statement.

1. Why do some people think that “anesthesia is ineffective”?

1. Physiological differences: different metabolic rates

The metabolism rate of anesthetics varies from person to person. For example, the metabolism of local anesthetics (such as lidocaine) is related to liver function, body weight, and age. If the patient's drug-metabolizing enzyme activity is high (such as an active CYP450 enzyme system), the anesthetic may be broken down faster, resulting in a shorter anesthesia time or a weakened effect.

2. Individual differences in neuroanatomy

The principle of local anesthesia is to block the conduction of nerve signals. However, for some people, the nerves are located deep, the surrounding tissues are dense (such as scar tissue), or the nerve fibers are distributed in a special way (such as variation of the nerves around the tooth roots), which may lead to obstruction of the diffusion of anesthetics and prevent them from taking full effect.

3. Psychological factors: anxiety and pain perception

Tension and fear can lower the pain threshold, and patients may misjudge the pulling and vibration during the operation as "pain" and mistakenly believe that the anesthetic has lost its effect. In addition, excessive anticipation of pain can also amplify discomfort.

4. Drug tolerance

Long-term use of certain drugs (such as alcohol and opioid analgesics) may induce increased liver enzyme activity and accelerate anesthetic metabolism; patients who repeatedly receive anesthesia may also develop a certain degree of tolerance due to decreased receptor sensitivity.

5. Problems with operation technique or dosage

Unsatisfactory anesthesia effects may also result from the doctor's deviation from the injection site, insufficient anesthetic dosage (especially for children and obese patients who need to adjust the dosage), or improper storage of drugs (such as the ineffectiveness of anesthetics if not refrigerated).

"Anesthetics" is a general term for anesthetic drugs, including general anesthetics, local anesthetics, analgesics, muscle relaxants, etc. People often say "I am not sensitive to anesthetics" generally refers to local anesthetics. The most common are some minor operations performed under local anesthesia. At this time, the patient's tension and anxiety will amplify various discomforts. However, "cesarean section" is not common. Most cesarean sections are performed with combined spinal-epidural anesthesia or epidural anesthesia. There will indeed be discomfort when the peritoneum is pulled. Of course, the anesthetic effect may not be ideal due to spinal anatomy, weight, etc., but modern anesthesia technology is very mature, and it is safe to switch to general anesthesia.

2. Does “anti-anesthesia physique” really exist?

First of all, there is no clear definition of "anti-anesthesia constitution" in medicine, but certain hereditary diseases may affect the effect of anesthesia.

"Insensitivity to anesthetics" is more the result of multiple factors rather than an absolute "physical problem". Through full communication between doctors and patients and scientific adjustment of the plan, most patients can achieve satisfactory anesthesia effects. If you have experienced multiple anesthesia failures, it is recommended to consult an anesthesiologist to identify potential causes and develop an individualized strategy.

Anesthesia is a precise science and one of the cornerstones of modern medicine. It allows countless patients to receive treatment without pain and provides a guarantee for the development of surgical operations. With the advancement of medicine, anesthesia technology will become safer, more precise, and more comfortable, bringing a better experience to patients!

Lu Zhixia, Department of Anesthesiology, Hebei Provincial Hospital of Traditional Chinese Medicine

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