Increased Accuracy and Safety in Spinal Tap with PASS – An Ultrasound Guided Lumbar Puncture Procedure

PASS (Point-Assisted Spinal Sonography), an ultrasound-guided lumbar puncture device from Chula physicians and engineers, helps increase accuracy and confidence in spinal puncture procedures while reducing risk and pain for patients.

Newswise – No one wants to be repeatedly pricked with a needle, especially when that needle pokes into the spinal cord. We all pray that the doctor can do it precisely in one fell swoop. However, errors do occur depending on the experience and expertise of the doctor, as well as the physical conditions of the patient.

“An error in performing a lumbar puncture (LP) could affect the patient’s entire life! We don’t want to see patients suffer and be harmed by our treatment.” Associate Professor Ketchada Uerpairojkit, MD, Department of Anesthesiology, Faculty of Medicine, Chulalongkorn Universitydiscusses the motivation for designing the Ultrasound-Guided Lumbar Puncture or PASS – Point-Assisted Spinal Sonography device to elevate the standard of care and safety for patients.

This innovation is a collaboration between the Faculties of Medicine and Engineering of Chulalongkorn University which include, besides Assoc. Teacher. Dr. Ketchada, Associate Professor Dr. Wirinaree Kampitak and Dr. Banjobphorn Songthammawat from Department of Anaesthesiology, Faculty of Medicine, Chula, Assistant Professor Dr. Werayut Srituravanich and Mr. Thiwa Nantapak from Department of Mechanical Engineering, Faculty of Engineering, Chula.

The origin of PASSS innovation

Assoc. Prof. Dr. Ketchada explained that lumbar puncture (LP) or lumbar puncture is a method used to reduce pain during an operation, also known as epidural or spinal block. It calms the sensory nerves by anesthesia through the spinal canal, which makes the patient’s body immobile and numb from the abdomen to the toes. This method is often used for surgical procedures such as cesarean section, uterus, ovary, hernia, hip, knee and leg surgery, or natural childbirth pain blocking , etc. Moreover, LP is also used in chemotherapy and diagnosis of leukemia, meningitis, etc.

“An anesthetist will ask the patient to lie in a fetal position, or sit up and lean forward so they can palpate the patient’s spine to find where to insert the needle and give a block regional so that the patient does not feel pain during and after the surgery This reduces the use of anesthetics The patient will feel comfortable during the surgery which is safer and less expensive than general anesthesia This will also reduce the spread of respiratory pathogens, including COVID-19 Anesthesia can also be given in combination with a regional block to speed post-operative recovery and early discharge.

Typically, to administer LP, the physician must palpate the iliac crest and spine while measuring the direction and depth of insertion of the needle into the spinal canal. The lumbar spinal canal approximation at levels 2 – 3 or 3 – 4 may not be successful every time.

“Performing a lumbar puncture may not be successful in a single attempt. Patients may have to go through several attempts before the procedure is complete as the spinal canal is quite deep and obscured by bones, tissues and ligaments, so the needle must pass through a small opening invisible to the eye .

According to Assoc. Teacher. Dr. Ketchada, the risk of error in the LP is approximately 10-50% depending on the experience and expertise of the anesthesiologist, as well as the age and physical conditions of the patients who may add obstacles to the procedure, such as obesity, spinal curvature abnormalities or spinal stenosis.

“With patients who are overweight, have a spinal deformity, spinal stenosis, or spinal fuse, there is a higher risk of failure and a greater chance of hitting the bone or joints. nerves, causing excruciating pain to patients.Some may have internal bleeding and also the risk of paralysis.

Therefore, the introduction of ultrasound to facilitate access to the spinal canal is one of the factors that increase the chances of success, since it allows precise visualization of the position, orientation and depth of the needle.

PASS precisely defines the LP location, increasing patient safety.

The One-time assisted spinal ultrasound (PASS) is an ultrasound-guided device designed to engage the ultrasound probe that scans the precise location, degree and depth of needle penetration into the spinal canal to reduce the risk of the needle hitting the spine and decrease the pain for the patient.

“In practice, the anesthesiologist cannot insert the needle in the best position from the obtained image because the ultrasound probe blocks the position of the needle, but PASS allows precise insertion of the needle with less risk of the needle hitting the bone or internal vessels,” says Assoc. Teacher. Dr Ketchada.

The PASS has two components: a “frame” designed to fit over the ultrasound probe and a “needle guide slot” to control the direction of the needle to enter the spinal canal. The needle guide slot is disposable to prevent infection, but the frame can be disinfected and reused 10 times.

Assoc. Prof. Dr. Ketchada explained Operation PASS as follows:

  1. Assemble the sterilized frame and needle guide slot.
  2. Put PASS on the ultrasound probe.
  3. Do an ultrasound until the spinal canal is visible.
  4. Pause imaging to measure location and position of LP from screen.
  5. Unscrew the ultrasound probe from the PASS frame
  6. Insert the needle through the “needle guide slot”, which will manually guide the needle to the target (instead of drawing a line on the patient’s skin), it will cross the skin into the subarachnoid space of the spinal cord until the measured depth is reached.
  7. Slowly remove the PASS frame. Be careful not to let the needle move.
  8. Aspirate cerebrospinal fluid from the puncture site.

PASS and its 4 distinctive designs

PASS is designed to optimize the performance of anesthesiologists when administering epidurals, general practitioners or neurologists who need to diagnose disease by lumbar puncture. Assoc. Professor Dr. Ketchada summarized the four strengths of PASS as follows:

  1. Security – PASS is made of medical grade non-toxic resin for lightweight and safe medical devices.
  2. Ergonomic design – designed to be easy to use with the ultrasound probe.
  3. Affordable price – the PASS frame can be reused after sterilization, reducing waste and costs, but the needle guide slot, which comes into direct contact with the needle, is contaminated and must be disposed of.
  4. Distribution – Collaboration with ultrasound equipment companies is possible to design a PASS that adapts to the different models of ultrasound probes. It is easy to produce. Production capacity can be increased quickly.

However, PASS has some limitations.

“Each brand of ultrasound machine has different probes, so we need to create a suitable model for each probe. We also need to calibrate the device to be more accurate, because there are still some errors,” Assoc. Prof. Dr. Ketchada has explained.

Chula Piloting the use of the PASS for safe treatment.

The PASS was a prototype medical device presented at the International Conference of Anesthesiologists in late 2020. Since then, anesthesiologists at King Chulalongkorn Memorial Hospital have been using the PASS in difficult cases. He also serves as a training pilot for 6th year medical students in the Faculty of Medicine’s Department of Anesthesiology, practicing on cadavers.

Currently, the PASS research and development team plans to expand its use in a commercial setting and is supported by Chulalongkorn University Technology Center (UTC).

“The team has already registered with the FDA and filed a patent application since September 2021. Medgateways has been entrusted with production and development. PASS is now available for sale at 2,000 baht/set. A passage consists of 1 frame and 10 needle guide slots,” explains Assoc. Teacher. Dr Ketchada.

In the future, the team will produce ultrasound-guided PASS with mobile phone/tablet connection, which will make the procedure even safer and more convenient for doctors. Training for medical students and residents of hospitals and centers will also be organized.

“We hope PASS will provide physicians with a more accurate tool to help patients and help close the gap in access to safe treatment in the future,” Assoc. said Professor Dr Ketchada.

For details, please contact Assoc. Teacher. Dr Ketchada Uerpairojkit, Department of Anaesthesiology, Faculty of Medicine, Chulalongkorn University, Rattanawithayapat Building, 9th Floor, Rama 4 Road, Pathumwan, Bangkok Tel. +66-2256-4000 ext. 60904-9, email: [email protected]

Hospitals, medical facilities or businesses interested in using the PASS to increase the success of lumbar punctures and reduce the risk to patients can contact Medgatewaysmanufacturer and distributor of PASS, 222/113 Teparak Road Bangplee Yai, Bangplee, Samutprakarn 10540, Tel: +668-4754-9493,

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