raquianestesia

Raquianestesia, or spinal anesthesia, is a regional anesthesia technique in which a local anesthetic is injected into the subarachnoid space surrounding the cauda equina. This produces a reversible blockade of nerve conduction at spinal levels, leading to sensory and motor anesthesia of the lower body. The spread of the block depends on the drug’s baricity, dose, and the patient’s position.

Indications include surgeries of the lower abdomen, pelvis, perineum, and lower limbs, as well as cesarean sections and certain urological or gynecological procedures. It is typically chosen for its rapid onset, reliable block, and avoidance of airway instrumentation in suitable patients. The procedure is commonly performed as a single-shot injection or, in some cases, with intrathecal opioids to enhance analgesia.

Technique involves placing the patient either in a sitting or lateral decubitus position, performing a sterile lumbar puncture at approximately L3–L4 or L2–L3, and injecting a small volume of local anesthetic into the subarachnoid space. The onset is usually within minutes, with the level and duration of anesthesia determined by the drug, dose, and baricity. The patient is then monitored for hemodynamic changes, as sympathetic blockade can cause hypotension.

Risks and complications include hypotension, high spinal anesthesia with potential respiratory compromise, post-dural puncture headache, back pain, urinary retention, infection, bleeding, nerve injury, and, rarely, arachnoiditis. Contraindications include patient refusal, infection at the puncture site, coagulopathy, increased intracranial pressure, severe hypovolemia, or allergy to local anesthetics.

Historically, spinal anesthesia was developed in the late 19th century and refined in the early 20th century, with August Bier among its early proponents. It differs from epidural anesthesia in that it provides a dense, rapid block from a single injection without catheter placement.