an ultrasound guided automated spinal landmark identification system

Conditions: Spinal Anaesthesia; Obesity

Summary: neuraxial ultrasonography has been shown a safe and effective technique to enhance the overall success rate of lumbar puncture and reduce the number of injection attempts. however, the current blind palpation landmark technique is known to be highly inaccurate and may increase the risk of multiple insertion attempts, patient suffering and complication rates such as spinal cord injury. various clinical studies have confirmed the effectiveness of ultrasound imaging compared with the traditional palpation method. however, none of the present system can achieve real-time guidance. the overall aim of this proposal is to develop an ultrasound guided automated spinal landmark identification with real-time neuraxial needle insertion system (usine) to improve patient safety and efficacy of neuraxial procedure needle insertion success. this will be achieved in 4 phases of technology development and clinical trial phases. the investigators will recruit 20 subjects in a prospective cohort study to investigate the spinal needle first attempt success rate as a clinically relevant outcome. the secondary aim is to develop an automated spinal landmark identification algorithm using image processing to identify spinal landmarks in 50 obese patients. third phase objective will be to obtain clinical data, and evaluation and annotation of the clinical data of spinal ultrasonography in 65 obese patients (bmi \> 30kg/m2), whereas the fourth phase will measure the usine identification accuracy and first-attempt puncture success rate of usine in a clinical study of 65 obese patients (bmi \> 30kg/m2).

this is a prospective cohort study to evaluate the efficacy and accuracy of ultrasound guided automated spinal landmark identification with real-time neuraxial needle insertion system (usine). the subjects assume a seated position and the lower back is exposed. ultrasound gel will be applied to the lower back lumbar spine and the investigator will place an ultrasound curved array probe around the sacral region. the graphical interface of the software, integrated with the wireless ultrasound probe and ultrasound machine, will inform the investigator when the software has positively identified the sacrum. the investigator will then move the probe in a steady vertical upward longitudinal direction until the l3/4 interspinous space is identified by the program. the ultrasound algorithm will identify the skin surface marking. the longitudinal section of the scan will be completed and the investigator will turn the probe 90 degrees clockwise around the probe center to the transverse view. the transverse scan consists of minimal vertical movements by the investigator who will obtain images using the ultrasound probe. the software will signal when the correct identification of the ligamentum flavum is visualized. the scan sequence will be completed. the first phase will involve 20 non-obese patients who are undergoing neuraxial anaesthesia or analgesia. the system is used prior and during needle insertion to provide real-time guidance for the anaesthetists. the neuraxial needle insertion is conducted manually by the anaesthetist as per routine practice. in the second phase, 50 obese patients (body mass index more than 30) will be recruited to investigate and develop an "obesity" mode visualisation of the ultrasound guided automated spinal landmark identification. this will be to advance the technology to evaluate more difficult anatomy and more complex neuraxial needle insertion in future work plan. the patients' back will be scanned to obtain the images. the neuraxial needle insertion is conducted manually (i.e. independent of the ultrasound results) by the anaesthetist as per hospital routine practice. the third phase involve data collection and annotation of spinal ultrasonography in 65 obese patients, followed by a fourth phase to measure the usine identification accuracy and first-attempt puncture success rate in 65 obese patients.

Eligibility criteria:
inclusion criteria: first phase: * age 21 - 75 years old patients who require neuraxial anesthesia for surgical procedure; * normal body mass index (weight 40-90 kg, height 140-180cm). second-fourth phases: * obese patients aged between 21-75 years old; * body mass index more than 30. exclusion criteria: * history of scoliosis; * history of spinal instrumentation; * drug allergy to ultrasound transmission gel; * visible wound or injury in the lumbar spine.

Keywords: spinal anaesthesia neuraxial ultrasonography landmark identification