Spinal Anesthesia Using a Needle Through Needle technique-a Retrospective Report of 1862 Cases

Compared to general anesthesia, intraspinal anesthesia offers certain technical advantages that are irreplaceable. However, specific patient populations such as those with obesity, a history of spinal surgery or pathological changes pose challenges to the traditional blind intraspinal puncture technique. The success rate of the initial intraspinal puncture guided by ultrasound was significantly higher compared to the blind puncture group. Nevertheless, there is still controversy regarding the differential application effects between ultrasonic-assisted positioning and real-time ultrasound guidance in intraspinal anesthesia. This study retrospectively examines 1862 cases of real-time ultrasound-guided sagittal oblique approach needle effect during lumbar punctures, providing clinical evidence-based references for near real-time ultrasound-guided lumbar punctures using a sagittal oblique approach.

The history of intraspinal anesthesia dates back to the late 19th century, when initial attempts were made to administer anesthesia through the spinal cord cavity. Over time, this technology has been enhanced and refined, leading to the administration of local anesthetic drugs into the spinal canal for temporary blockade of spinal and peripheral nerve transmission. This effectively alleviates pain in specific areas of the body, induces muscle relaxation, and meets surgical requirements. Consequently, intraspinal anesthesia has become a crucial component of modern anesthesiology.

Compared with general anesthesia, intraspinal anesthesia possesses irreplaceable technical advantages: firstly, it primarily affects the spinal cord with minimal impact on the central nervous system; secondly, it requires smaller drug doses that are less likely to cause systemic drug poisoning reactions; additionally, by controlling the block plane precisely, patients' respiratory function and cardiac autonomic function can be maximally preserved while avoiding respiratory system injury or infection as well as cardiovascular and cerebrovascular complications caused by controlled ventilation or systemic drug stimulation. Moreover, since local anesthetics only act on the maternal spinal cord during childbirth procedures specifically designed for physiological delivery purposes，intraspinal anesthesia is highly favorable for both mother and fetus alike，making it almost always preferred over other forms of anesthesia.

However, for some special patients, such as patients with obesity, spinal surgery history or pathological changes, the operation of intraspinal anesthesia poses a challenge to the traditional blind puncture. Blind puncture relies on the "sense of loss of resistance" for such patients may be misjudged, and multiple punctures may also lead to accidental dural puncture or spinal cord injury. In 1984, anesthesiologists used ultrasound for the first time to measure the depth of the epidural space, providing advance guidance for blind procedures, and through this improvement, complications of blind puncture have been significantly improved. Ultrasound also showed an advantage in the diagnosis of neonatal epidural hematoma. Although the resolution of ultrasound images was low at that time, the range of abnormal epidural structures under ultrasound was still clearly visible. Maternal obesity is one of the important factors for blind intraspinal puncture. The increase of subcutaneous fat easily leads to the difficulty of palpation of spinous process. In addition, the deep intraspinal structure also increases the uncertainty of blind intraspinal puncture. Scanning with a sagittal posterior median approach will help to identify the spinous process, vertebral number, intervertebral space width, and epidural space depth, thereby providing specific information about the intraspinal structure prior to blind puncture. In addition, ultrasound can guide the placement of the epidural catheter in children and confirm the appropriate catheter height. Recently, more and more studies have pointed out that with the improvement of the resolution of ultrasonic equipment, the success rate of the first puncture of ultrasound-guided intraperitoneal puncture has been significantly improved compared with that of the blind puncture group. Ultrasound visualizes the structure of part of the spinal canal and provides a new option for some complex intraspinal puncture. Moreover, since ultrasound guidance reduces the operational difficulty of intraspinal puncture, more and more anesthesiologists prefer to use this technology.

In elderly patients, calcification of ligaments, narrowing of vertebral space, and stiffness of spinal joints will affect the position placement before intraspinal puncture and the quality of ultrasound imaging of intraspinal structures. Moreover, due to the possible obstruction of the epidural space by the spinous process, the posterior sagittal approach may not provide a good indication of the dorsal dural membrane. Although the transverse paramedian approach also reduces the ligament level of puncture and the influence of spinous process bone on the puncture path, the section of ultrasound scan still needs to pass through the ligament and spinous process space required by the traditional blind method. Therefore, for patients with obvious gap calcification or narrow spinous process space, the ultrasonic exposure of the epidural space still has problems. Based on this consideration, the ultrasound scanning Angle was improved, and it was found that the probe placed in the medial oblique position of the parasagittal could well avoid these obstacles, thus making the ultrasonic image of the spinal canal clearer, which further reduced the difficulty of ultrasound-guided intraspinal puncture and improved the puncture efficiency. At the same time, the development of the puncture needle is also clearer, and it is easy to perform real-time ultrasound-guided intraspinal puncture.

At present, the ultrasound guided subarachnoid anesthesia (lumbar anesthesia) puncture needles we use are generally 24G or 25G fine needles. For ligament calcification or resistance puncture, the fine needle body is easy to deform or bend. Therefore, we use a larger injection needle as the guide needle for lumbar anesthesia needles, that is, the "needle in the needle" technology. The technique avoids the direct use of epidural puncture needle as a guide for tissue damage and reduces the risk of accidental dural puncture. At the same time, we can directly use the needle for local anesthesia at the puncture point in the lumbar anesthesia puncture kit, and continue to indplace it under the skin as a guide needle after the injection of subcutaneous local anesthetic to avoid multiple skin puncture. Under the low frequency ultrasonic probe, the linear development of the local anesthesia needle can also help us to identify the puncture direction.

Previous studies with small samples have confirmed that ultrasound can assist in locating vertebral segments, judging the depth and visibility of the dural membrane, and providing real-time guidance for intraperitoneal puncture or epidural catheter placement. All of the above application methods have been proved to significantly improve the success rate of puncture, shorten the puncture time, and reduce the difficulty of puncture. However, the differences between the application effects of ultrasound assisted positioning and real-time ultrasound guidance in intraspinal anesthesia are still controversial. Up to now, there is no large sample study to analyze the clinical application effect of ultrasound real-time guided lateral sagittal oblique approach needle intraacupuncture lumbar anesthesia technique.

Studied in this paper through a retrospective reports 1862 cases of real-time ultrasound guidance in sagittal oblique approach by needle effect, the clinical application of lumbar hemp for near real-time ultrasound guided lumbar hemp in sagittal oblique approach needle to provide reference of clinical application of evidence-based medical evidence.

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