Abortion surgery, almost one of the smallest. Because it is small, it is easy to relax over time. Many gynecologists will call and say: Anesthesia teacher, come and give me some numbness. Listen to that, it's a small operation that can't be simpler.
However, the department of anesthesiology has never slackened. Just as the so-called "careless loss of Jingzhou", the danger often occurs when it is slack. Like the "small anesthesia" of the outpatient clinic, it is almost the most worrying thing for the anesthesiologist.
The reason for this is that almost everyone, including surgeons, nurses or patients and their families, considers this to be a minor procedure and an unlikely dangerous thing; in addition, the preoperative examination of such surgery is almost always difficult to compare with the comprehensiveness of inpatient surgery. This means that there may be uninspected areas. Coupled with the fact that the equipment of the outpatient operating room is relatively behind that of the inpatient operating room, the equipment base of rescue is one grade behind.
Because of this, the anesthesiologist will be doubly careful and observe the anesthesia process in detail.
In anesthesia, we observed a phenomenon: after the bolus anesthetic, the patient often said "What taste?" at the moment of falling asleep. ”。
At first, we felt that it was an isolated phenomenon. But with the increase in cases, we believe that there must be a certain mechanism.
However, domestic and foreign literature was searched and no similar studies were found. Even, not reported. We have therefore decided to analyse this phenomenon. It is hoped that the analysis in this article will provide some inspiration and support to healthcare professionals who are interested in research.
Let's describe exactly what happened: a 2 mg bolus for kilogram body weight, which was completed in 5 seconds. Until then, no medications should be used that affect the patient's consciousness or feelings. To avoid injection pain, a certain amount of local anesthetics can be added to prevent it. This can be detected the moment the anesthetic flows through the heart through the heart to the brain.
Two points need to be reminded: for patients with unstable circulation or anesthesiologists who do not have extensive control of the respiratory tract, do not try easily; before pushing the drug, be sure to remind patients of a high degree of energy to experience whether there is abnormal taste.
One might question: Why push so fast?
Although rapid bolus propofol has the disadvantages of respiratory depression and causing circulatory fluctuations, this anesthesia method is more suitable for anesthesia in outpatient abortion.
Outpatient abortion anesthesia, the pursuit of short flat fast. That is, safety and efficiency are indispensable. In terms of safety, it does not mean that slow pushing drugs are necessarily safe. Slow push drugs, the concentration of anesthetics that reach the brain in a short period of time is insufficient, and patients need relatively large doses of anesthetics to "fall asleep".
A larger dose of anesthetic means that the body needs relatively more time to metabolize these anesthetics, and may even cause drug accumulation. In this way, it undoubtedly slows down the efficiency of outpatient surgery and increases the difficulty of care afterwards. On top of that, it may add additional risks. With rapid bolus, anesthesiologists will keep the most dangerous stages to their own care more, and safety is greatly improved.
Back to the point: What is this "taste?" that patients say? ", how did it come about?
We noticed that this abnormal reaction appeared a few seconds after the dosing and before the "numbness passed".
We all know that the olfactory nerve is the sensory nerve, and the primary neuron is a bipolar neuron, which exists in the mucous membrane of the upper part of the nasal cavity; its surrounding part penetrates the mucous membrane at the top of the nasal cavity, the upper part of the nasal septum and the medial side of the supranasal nail, forming a cilia receptor, whose ascending axons make up the olfactory nerve. The olfactory nerve transmits the olfactory impulse to the olfactory bulb, which then passes through the olfactory triangle, anteriorly penetrating, transparent septum to the olfactory center.
If you are still ignorant of these, go directly to the anatomical path: the olfactory nerve passes through the sieve hole of the sieve bone sieve plate, passes through the dura mater and arachnoid membrane, and enters the olfactory bulb of the anterior fossa. The olfactory bulb is located under the frontal lobe of the cerebral hemisphere or on the orbital surface. Olfactory nerve fibers form synaptic structures with the monk cap cells of the olfactory bulb. The axons of the monk cap cells form an olfactory beam, which is divided into two clusters of olfactory streaks, the medial and the outer. The lateral olfactory streaks stop at the pear-shaped cortex in front of the temporal lobe, and the medial olfactory streaks project through anterior conjunction to the contralateral structures related to the sense of smell.
Although it may seem extremely complex and even headache- it is generally followed: the mucous membrane of the olfactory area is distributed in the middle of the top of the nasal cavity, down to the upper part of the nasal septum, and the upper part of the lateral wall of the nasal cavity. Then, we need to know what the supply artery of this part of the mucous membrane is. Because only the arteries can bring the anesthetic here in the first place.
Anatomy can be seen: the ophthalmic artery separates the anterior and posterior sieve arteries from the optic nerve tube into the orbit. Both pass through the corresponding anterior and posterior sieve holes into the sieve sinus, and both travel closely against the top of the sieve in the grooves or bone tubes formed by the crests. After that, leave the sieve sinus, enter the anterior cranial fossa, and follow the sieve plate through the small slit next to the cockscomb into the nasal cavity. The anterior sieve artery supplies the anterior, middle, and frontal sinuses, as well as the anterior upper part of the lateral wall of the nasal cavity and nasal septum. The posterior sieve artery supplies the posterior sieve sinuses as well as the lateral wall of the nasal cavity and the posterior upper part of the nasal septum.
Where do the eye arteries come from?
The ophthalmic artery is the main branch of the internal carotid artery and is also an important channel for communicating the internal and external blood vessels in the skull.
At this point, we can lock in the target. If the olfactory nerve directly receives the signal of "abnormal taste", it can only be taken by this route.
Some people say: What if it is an illusion in the brain center?
It is also possible that we will look at similar studies:
Among them, the Journal of Clinical Anesthesiology published an article entitled "Two Cases of Change in Smell and Taste after General Anesthesia ~ Tooth Extraction". Of course, most of the articles are reports of such cases.
The discussion part of the article is frank and clear, although the mechanism of postoperative olfactory disorders is not clear, but multiple literature suggests that anesthetic drugs may be the biggest trigger. These narcotic drugs are thought to affect the central or peripheral nervous system and cause damage to the epithelium of the olfactory and taste nerves. In addition to lidocaine and ketamine, studies have shown that propofol can also cause loss of smell and taste. Propofol stimulates inhibitory γ aminobutyric acid type A receptors of the central nervous system, thereby inhibiting olfactory and taste pathways.
So there's reason to guess what happened at the time. The patient smells an abnormal smell, perhaps caused by the impact of anesthesia on the olfactory nerve or olfactory center. As for whether it is the olfactory nerve or the olfactory center, we may never know. Because, the memory of a moment before "going to sleep" is missing. Even if the patient can tell which smell is similar at that time, it may not be too late to express it, let alone remember.
However, this phenomenon reminds us that this area is worth further study. Perhaps, in the future, we have the opportunity to truly reveal the mechanism of action of propofol, and even the mechanism of general anesthesia.
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