Lumbar punctures and epidural catheterizations are common procedures. Failed procedures result in loss of diagnostic information or inadequate analgesia or anesthesia. Ultrasound has been shown to reduce the risk of failed procedures in addition to reducing the risk of traumatic procedures and the number of needle insertions and reinsertions. The 4 P’s (position, preparation, projection, and puncture) continue to remain the very essence of these procedures.
Historical note and terminology
Lumbar puncture. Lumbar puncture is a relatively common procedure. Quincke performed the first lumbar puncture in 1891 to relieve increased intracranial pressure in children with tuberculous meningitis (28). Since then, lumbar punctures are used for diagnostic sampling of the cerebrospinal fluid to evaluate for suspected infections of the central nervous system, hemorrhage, neoplasm, or inflammatory disorders as well as for delivering therapeutic agents to the intrathecal space (34). The performance of lumbar punctures and epidural catheterizations relies primarily on the palpation of anatomical landmarks, the angle of needle progression, and the distance from the skin to the target space; hence, the skill of the operator is a major influencing factor. It is expected of the operator to have a good knowledge of the local anatomy and the ability to visualize the same during the procedure. Though it is preferable to obtain a CSF specimen prior to antibiotic administration, under no circumstances should therapy be unduly delayed for the sake of a lumbar puncture in a patient with frank signs of meningitis or sepsis.
Epidural injection. Sicard and Cathelin were the first to perform and describe lumbar epidural anesthesia in 1901 (24). It was used frequently in the early 1900s because of the relative safety compared to complications associated with general anesthesia at the time. Since then, epidural anesthesia has been regarded as a safe procedure although some authors have suggested that neurologic complications, first reported in 1921, have been underreported (40).
Lumbar epidural anesthesia refers to the injection of an anesthetic or analgesic agent into the lumbar epidural space to induce anesthesia or analgesia of the lumbosacral spinal roots. The epidural space consists of the region between the dura and periosteum of the vertebral bodies. This space contains areolar tissue and the internal vertebral venous plexus. The epidural space is largest at the level of L2. The effect of epidural anesthesia after epidural injection of a specific dose of local anesthetic differs considerably among individuals. Factors affecting the distribution of neural blockade by local anesthetics in epidural anesthesia include age, height, weight and body mass index, pregnancy, dural surface area, choice of epidural insertion site, patient position and gravity, needle direction and catheter position, injection through needle versus injection through catheter, epidural catheter design, fractional versus single bolus injection, speed of injection, epidural pressure, pressure in adjacent body cavities, total dose, concentration versus volume, the anesthetic agent or agents used alone or in combination, and whether epidural anesthesia is used alone or with other forms of anesthesia or analgesia (38).