Does spinal anesthesia hurt?

Having worked in the anesthesiology department for many years, I have seen too many patients who are nervous and anxious before surgery. Many of them are afraid of the pain of spinal anesthesia. Most of them get information from searching online and reading other people's complaints that the injection during spinal anesthesia is particularly painful. Let me give you a detailed introduction to what spinal anesthesia is.

In fact, the spinal anesthesia that everyone talks about is the subarachnoid block in our professional terminology, commonly known as spinal anesthesia. It is a form of intrathecal anesthesia. This anesthesia method also has epidural block, commonly known as epidural anesthesia. If a catheter is inserted into the epidural, local anesthetics can be injected into the epidural space through the catheter to achieve a blocking effect. The drug is injected intermittently according to the half-life of the local anesthetic to achieve a long-term blocking effect, which is called continuous epidural block. If local anesthetics are also injected into the subarachnoid space, the epidural catheter can also be inserted for continuous anesthesia, which is a combined spinal-epidural anesthesia. Another type of anesthesia that injects local anesthetics into the sacral canal to achieve a blocking effect is intrasacral anesthesia, which is actually a type of epidural block and is suitable for low-position surgeries such as the rectum, anus and perineum. These anesthesia methods are currently in use.

Our hospital performs a lot of anorectal surgeries, and most operations last 40 minutes to 1 hour. About 95% of our anesthesia is spinal anesthesia. Below I will mainly introduce this anesthesia process. After the patient enters the operating room, intravenous infusion, ECG, blood pressure, and finger pulse oxygen monitoring are connected, and then the anesthesia is completed in the side-lying position (as shown below).

First, about 3 ml of 1% lidocaine is infiltrated for local anesthesia, and then a No. 5 fine needle (outer diameter 0.5 mm) is used to slowly puncture the subarachnoid space with the needle tip. After the puncture is in place, clear cerebrospinal fluid can be seen flowing out slowly. 0.375% ropivacaine is injected into the subarachnoid space at a certain speed. During the process, the feet will feel hot. After the operation is completed, the anesthesia is completed, the patient is transferred to the lithotomy position, and then the operation begins. Our anesthesia effect takes effect immediately after the spinal anesthesia is injected, reaches a peak in about 5-8 minutes, and lasts for about 120-150 minutes. This onset time and maintenance time are related to the type, dosage and concentration of the injected local anesthetic.

Now that the anesthesia method has been explained, does it really hurt to get anesthesia? First, let me introduce the needle used for anesthesia (see the picture below). We choose the thinnest No. 5 needle (outer diameter 0.5mm) in the picture below. This is the inner needle in the combined spinal-epidural anesthesia package, which is much thinner than the No. 9 (outer diameter 0.9mm) spinal anesthesia needle in the previous spinal anesthesia package. With such a thin needle combined with the effect of local anesthetics, this operation is actually not painful. The pain is a little bit painful when the needle enters the skin during local anesthesia, and there will be a slight soreness and swelling when the spinal anesthesia needle is punctured later, but there is no pain. So it is really not painful to get spinal anesthesia in our hospital.

You can see that there is also an 18-gauge (outer diameter 1.8mm) needle in our picture, which is the thickest needle in the picture. It is the needle we use when completing epidural anesthesia. In combined spinal-epidural anesthesia, the first step is to puncture the 18-gauge needle into the epidural space, and then insert the 5-gauge needle into the 18-gauge needle and puncture the subarachnoid space to complete the operation. Similarly, before the puncture of this thick needle, we will also use local infiltration anesthesia technology first, and then slowly puncture the tip of the 18-gauge needle to reach the epidural space. During this process, the soreness and swelling of the waist will be more obvious than that of the 5-gauge needle. During the process of the 5-gauge needle being inserted into the subarachnoid space through the 18-gauge needle, the patient does not feel anything. Pain is also caused when the needle punctures the skin during local infiltration anesthesia. However, if the patient is obese in the waist, elderly with severe bone hyperplasia, or degeneration of the lumbar spine, and cannot complete the side-lying bending position well, there will be difficulties in puncture, resulting in repeated punctures, and the situation of anesthesia injections being very painful may occur as netizens say.

With the continuous advancement of anesthesia technology, the continuous improvement of the quality of anesthetics, the continuous improvement of people's lifestyles, and the increase in people's awareness of calcium supplementation, the number of patients with difficult punctures will decrease. Of course, anesthesiologists will also continue to strive to improve in the direction of making the entire hospitalization painless.

[1] Bao Junxian, Hong Yulan, Yu Yan. Effect analysis of 25G fine needle low-dose spinal anesthesia and conventional spinal anesthesia in anorectal surgery[J]. Systems Medicine, 2023, 8(15): 96-99.2023.15.096.

Li Yan, Department of Anesthesiology, Hebei Provincial Hospital of Traditional Chinese Medicine

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