Understanding Spinal Anesthesia: Your Complete Guide

Spinal anesthesia, a form of locoregional anesthesia, injects a local anesthetic into the cerebrospinal fluid for effective anesthesia below a specific level. This technique is preferred for various surgeries, offering targeted anesthesia and rapid recovery.

Originating in the 19th century, spinal anesthesia has evolved, thanks to pioneers such as James Leonard Corning and Augustus Karl Gustav Bier, into a safe and effective method in many surgical fields, includingobstetrics andorthopedics.

Compared to general anesthesia, it reduces the risk of infections, blood clots, and respiratory problems, while allowing for spontaneous ventilation and faster recovery.

Adequate preparation and pre-anesthetic consultation are essential to minimize risks. Particular attention is paid to the patient's position for precise injection.

Continuous monitoring and the use of optimal local anesthetics ensure patient safety and comfort during and after the procedure. Spinal anesthesia is thus distinguished as an attractive option for many surgical interventions.

Additives and their effects

Additives, when combined with local anesthetics, play an important role in improving the quality, duration, and effectiveness of the nerve block. Opioids such as fentanyl, morphine, and sufentanil are often integrated to enhance post-operative analgesia.

Intrathecal morphine, for example, is capable of providing prolonged analgesia that can last from 12 to 24 hours, thus significantly decreasing the need for postoperative intravenous morphine.

Clonidine, an alpha-2 adrenergic agonist, can also be used to prolong the duration of the nerve block while improving analgesia. However, it can also induce an increased risk of nausea and vomiting. Glycopyrrolate is sometimes preferred to reduce these inconveniences, despite the fact that it may increase post-spinal anesthesia hypotension.

Agents such as midazolam or ketamine, known for their anxiolytic properties, can be administered intravenously to improve patient comfort during the procedure.

Despite the many advantages of spinal anesthesia, it can be associated with a number of immediate and short-term complications.Hypotension, frequently accompanied by nausea and vomiting, is one of the most common complications.

This hypotension is generally the result of intense vasoplegia that causes a drop in blood pressure, often requiring volume expansion and the administration of vasoconstrictors such as ephedrine, phenylephrine, or norepinephrine.

In addition, urinary retention is another frequently observed complication, particularly when caused by the intrathecal use of morphine, which may require the placement of a urinary catheter to facilitate urination.

Post-dural puncture headaches (PDPH) also represent a significant complication, especially in young adults. Although these headaches are generally spontaneously resolving, they can be intense enough to interfere with daily activities.

Management of adverse effects

Proactive management and careful monitoring of adverse effects and complications related to spinal anesthesia are essential.

To control hypotension, early volume expansion and the administration of vasoconstrictors are essential. It is important to monitor patients closely for any early signs of hypotension in order to take corrective action quickly.

To prevent and manage nausea and vomiting, serotonin 5-HT3 receptor antagonists may be effective, especially in the presence of intrathecal morphine. These agents significantly reduce the incidence of nausea and vomiting, thus minimizing the need for rescue antiemetics.

Urinary retention can be managed by placing a urinary catheter and, if necessary, by administering medication to facilitate urination. It is essential to restrict intrathecal morphine doses to reduce this risk.

Regarding post-dural puncture headaches, therapeutic abstention is often recommended before the fifth postoperative day, as these headaches generally tend to resolve spontaneously.

Spinal anesthesia has medical contraindications that must be carefully evaluated beforehand. Absolute contraindications include patient refusal, hemostasis disorders, infection at the puncture site, and proven allergies to amino-amide local anesthetics.

Patient risk assessment

Patient risk assessment is essential before performing spinal anesthesia.

This thorough assessment is particularly necessary for patients with progressive neurological diseases or specific cardiac conditions.

The decision to proceed with spinal anesthesia should always result from a rigorous assessment of the risks and benefits, in consultation with the patient.

In conclusion, spinal anesthesia offers a more comfortable and safer anesthetic experience, contributing to a faster and more pleasant recovery. It is essential to discuss the benefits and risks with your anesthesiologist to make an informed decision.

FAQ

What are the main indications and types of operation for which spinal anesthesia is generally used?

Spinal anesthesia is mainly used for operations on the lower half of the body, particularly in general, urological, gynecological, obstetric, and orthopedic surgery of the lower limbs. It is also indicated for vascular surgeries and perineal interventions. It is often chosen for cesarean sections, prolapse repairs, hysteroscopies, and operations on blood vessels in the legs.

How is spinal anesthesia performed, and what preparations are necessary before the procedure?

The spinal anesthesia procedure is performed either in a sitting or lying position on the side. A nasal mask with oxygen and an intravenous infusion are put in place, as well as a monitoring device for cardiac and respiratory monitoring. Local anesthesia of the skin is performed before the introduction of a fine needle to inject the local anesthetic into the cerebrospinal fluid between two lumbar vertebrae (generally L2-L3, L3-L4 or L4-L5).

Before the intervention, a meeting with the anesthesiologist is necessary to discuss medical history and preferences. The patient must be fasting in the hours leading up to the operation.

What are the main risks and side effects of spinal anaesthesia?

The main risks and side effects associated with spinal anesthesia include arterial hypotension, often accompanied by nausea and vomiting, post-dural puncture headaches, dorso-lumbar pain, and a feeling of thoracic constriction due to paralysis of the accessory respiratory muscles. There may also be rarer complications such as neurological damage, septic or aseptic meningitis, epidural hematoma, or an anaphylactic reaction to the products used.

In which cases could spinal anesthesia be supplemented by general anesthesia, and why?

In many specific cases, spinal anesthesia may be supplemented by general anesthesia. If the anesthesiologist is unable to perform spinal anesthesia, or if it does not produce sufficient effect in the area to be operated on, general anesthesia may be required. Furthermore, if the surgery is more complex or longer than anticipated, general anesthesia may be required to ensure patient comfort and safety.