Spinal anaesthesia is a form of neuraxial regional anaesthesia involving the injection of a local anaesthetic or opioid into the subarachnoid space, generally through a fine needle, usually 9 cm (3.5 in) long. It is a safe and effective form of anesthesia performed by nurse anesthetists and anesthesiologists which can be used as an alternative to general anesthesia commonly in surgeries involving the lower extremities and surgeries below the umbilicus. The local anesthetic or opioid injected into the cerebrospinal fluid provides anesthesia, analgesia, and motor and sensory blockade. The tip of the spinal needle has a point or small bevel.
Spinal needles are used to inject analgesia and/or anaesthetic directly into the CSF usually at a point below the second lumbar vertebra. Spinal needles enter the cerebral spinal fluid (CSF) through the membranes surrounding the spinal cord. An introducer needle is used in some cases to stabilise the insertion of the needle and aid insertion through tough skin. The needle and stylet are advanced towards the dura in the intevertebral space (the stylet stops tissue blocking the needle during insertion). An introducer needle is used in some cases to stabilise the insertion of the needle. Once through the dura and in position, the introducer is removed and the removal of the stylet enables CSF to flow into the needle hub. CSF can be collected for diagnostic purposes or a syringe may be connected to the spinal needle to inject anaesthetic agents or chemotherapy agents.
Procedures which use spinal anesthesia include:
• Orthopaedic surgery on the pelvis, hip, femur, knee, tibia, and ankle, including arthroplasty and joint replacement
• Vascular surgery on the legs
• Endovascular aortic aneurysm repair
• Hernia (inguinal or epigastric)
• Nephrectomy and cystectomy in combination with general anaesthesia
• Transurethral resection of the prostate and transurethral resection of bladder tumours
• Hysterectomy in different techniques used
• Caesarean sections
• Pain management during vaginal birth and delivery
• Urology cases
• Examinations under anaesthesia