LUMBAR PUNCTURE SAFETY TOOLRS02-Dr Ravi Selvaganapathy

By Daniel Ebere

Long Yao

PUNCHEON RESEARCH

LUMBAR PUNCTURE

Introduction● Lumbar puncture (LP)

is a procedure that extracts cerebrospinal fluid (CSF) from the subarachnoid space from the spinal space in the lumbar region of the lower back. ● The current problem is to control the insertion depth to protect injury due to over penetration.

● This project is improves the manual control to automatic control in the depth of insertion which will decrease the possibility of injury in lumbar puncture.

Original Objectives● Control the distance of insertion and the

force applied on the lumbar puncture needle.

● Automatic stop of the insertion to protect the nerve system.

● Move back mechanism to avoid over penetration due to the bounce of the dura mater.

● Minimize the weight of the lumbar puncture needle to better handle.

Objectives Achieved

● Emergency button to move the needle backwards

● Control the distance of insertion and the force applied on the lumbar puncture needle.

● Automatic stop of the insertion to protect the nerve system.

● Move back mechanism to avoid over penetration due to the bounce of the dura mater.

● Minimize the weight of the lumbar puncture needle to better handle.

Design criteria

Requirement Value Unit

No. Of DOF 1 -

Force range 0-20 N

Response time 51 ms

Speed 0-10 mm/s

Overshoot distance 0-8 [3] mm

Design details● Coaxial needle design made up of an

inner and outer needle.● The inner needle experiences the cutting

force ● The outer needle experiences the shear

force from surrounding tissues

Ft = Cutting forceFa = Actuator forceFs= Shear force from surrounding tissuesFh= Handling force

Procedure Points

● The cutting force should change as the inner needle goes through several tissues.

● Force sensor at the end of the hub of the cutting needle reads the force changes

● Outer needle takes the shear force● Force drops as the CSF area is reached● Brake is activated.● Tube is connected to the hub of the outer

needle to collect the CSF fluid when it

SIGNAL FLOW DIAGRAM

Testing

Summary of testingTest Number of test made

Motor Test 5

Force sensor Test 4

Force drop Test 4

Final assembly test 6

Step Motor Test Result● The stepper motor is

tested on its performance on acceleration , velocity and angular velocity.

● The relationship between actual velocity and angular velocity which is y = 0.314*x + 0.1163, where y is the angular velocity in rad/s and x is the actual velocity input in steps/s.

Force Sensor Test Result● The benefits of the dead

band compensation are that it can reduce the settling time and lower the steady state error.

● The calibration equation is y = 0.1943*x, where x is the sensor output and y is the value in N.

Final Assembly Test Result (Styrofoam)

● The insertion automatically stops when it penetrates the styrofoam plate. The overshoot distances are different for each sample.

Sample A Sample B Sample C

Final Assembly Test Result● The overshoot

distance should be with 8 mm. so sample A and sample C are accepted as successful insertion. So the successful rate is 75% in the 6 tests.

● The setting of the deadweight in the programing code is too large that decrease the sensitivity of the force sensor.

Overshoot distance of each sample

Societal and Economic ImpactsSocial Economic

● �USA-400,000 lumbar punctures per year

● �1/1000 injured every year

● �Reduced to 1/300,000● �Health-adjusted life

expectancy

● �Reduces public spending on health care

● �Increases disposal income of patients

Questions ?

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