The varying levels of oxygen concentration in the blood can be used as an indicator to determine whether or not a vaso-occlusive crisis is occurring. By using different optics techniques, such as pulse oximetry or photoplethysmography, these levels of oxygen concentration can be measured.
This device should be able to adjust to varying thicknesses.
Find a Correlation Between the Varying Levels of Oxygen Saturation in the Blood and the Level of Pain that an Individual May be ExperiencingA pain scale can be created that ranges from one to ten. Each number on the pain scale can correlate to a specific range of oxygen saturation levels.
Research shows that people diagnosed with sickle cell anemia share a similar hemoglobin-oxygenation curve as people without the disease (Figure 1).Therefore, the principles of pulse oximetry are applicable to people with sickle cell disease; the oxygen saturation measurements taken on a person with Sickle Cell Disease with a pulse oximeter should be accurate compared to people without the disease. Our group conducted three experiments mimicking a vaso-occlusive crisis to determine if oxygen saturation percentages differed during normal and vaso-occlusive conditions.
Methods of Data Collection. Vaso-occlusive crises were simulated by using a tourniquet. Different pulse oximeters were used to obtain the blood oxygen saturation percentages. These were the nanotracker, the medtroniklifepak 12 clinical pulse oximeter, and the AD Instruments MLT321 Pulse oximeters.
Table 1 shows the data collected from the photoplethysmograph otherwise known as the nanotracker. A vaso-occlusive crisis was simulated using a tourniquet; the nano tracker recorded the blood oxygen concentration during the simulation. The table shows that the standard deviation and the p values are very small. These were calculated using the built in Excel functions, and this shows that the data was significant.
Table 2 shows the data collected from the Medtronic Lifepak 12 Pulse Oximeter. This test also used a tourniquet to mimica vaso-occlusive crisis. The standard deviation and the p-values were also small for this experiment.
The third test was conducted in the same fashion as the first two, but we added a control measurement while using AD Instruments MLT321 pulse oximeters. A pulse oximeter was placed on each hand. A vaso-occlusive crisis was simulated in one arm (experimental), and the other arm remained in normal conditions (control). During the simulation, the pulse oximeters took blood oxygenation concentration readings.
T-tests were done on the sets of data within the three tables. The p-values shown were calculated using the T-Test function in Microsoft Excel.The results of the t-tests show that the O2 saturation decreased significantly when the tourniquet was placed on the arm. Therefore, it can be deduced that a pulse oximeter can detect a vaso-occlusive crisis. The pulse oximeter on the control hand read normal blood oxygenation levels while the pulse oximeter on the experimental arm read significantly lower blood oxygenation levels. By these experiments, it can be determined that a pulse oximeter can be used to detect the general location of a vaso-occlusion.
Our device will utilize an adjustable arm-band design. This will allow the device to conform to different sizes and allow for ease of use. A system of multiple LEDs and detectors will be used.
The benefits of a multiple LED system is that it produces more light which allows the detector to see dark spots better. Even if the crisis occurs outside of the emitance of the LED, our detectors can identify a crisis
We have developed a technique which will incorporate two pulse oximeters. This allows us to get a baseline reading while at the same time identifying a crisis. Preliminary testing has proven this method to be viable.
Recreating a vaso-occlusive crisis was important part of our research. We were able to recreate a vaso-occlusive by using a blood pressure cuff to slow blood flow to the extremities.
Here is a table of what our proposed pain scale will look like.
The table shown here shows an estimation for the total price of our budget. This includes the cost of producing the prototype and the cost for travel to perform immersions. Currently, there are no major competitors against our design. In some cases, a doctor can order a CT scan, which costs $1200 - $3200 (“CT Scan vs. MRI”).
Summary• Vaso-occlusion, which is the obstruction of blood flow in a vessel, leads to ischemia, chronic pain, and, if left untreated, tissue death (Yale et. al. 1349-1356)• Caregivers are routinely unable to correlate the magnitude of a vaso-occlusive event and pain in patients with sickle cell disease.
SummaryThe subjective pain scale is the primary method ofdetection • Patient ranks his/her pain on a scale of 1-10 • Contains no biometric data that relates severity of vaso-occlusion to pain
Summary• Purpose: develop a modified pulse oximeter that will measure oxygen saturation or perfusion levels in tissue.• Goal: determine a correlation between the oxygen levels and/or perfusion within the region of pain and the level of pain the patient is experiencing• The device will, hopefully, lead to more efficient treatment
Sickle Cell Disease• Malformation of hemoglobin• Results in sickle-shaped red blood cells with altered function and lifespan• Complications include painful vaso-occlusive episodes, ACS, stroke, pulmonary hypertension, multi-organ damage, decreased life-span (Conran 1-2)• Affects 70,000-100,000 individuals in the US (SCDAA.com)
Vaso-Occlusion• Most common complication of sickle cell disease• Painful• Can occur in arms, legs, chest, abdomen (American Family Physician 1027)
Vaso-Occlusion• Sickled cells cannot deform to pass through small vessels• Endothelial wall damage(Conran 4-8)
Pain• Caused by infection and/or ischemia• Pain occurs in legs, arms, lower back, knees, chest, abdomen• 5% of patients with sickle cell disease have 3-10 pain episodes per year• Pain crises are the primary reason for ER visits
Pain ManagementCommon Opioids Used to Treat Mild to Moderate Pain in Sickle Cell Disease Drug Usual oral starting dosage in adults Comments and precautions Codeine 30 to 60 mg Every 3 or 4 hours Available in liquid or tablet form, alone or in combination with acetaminophen Side effects: impaired ventilation (histamine release possibly triggering bronchospasm) and increased intracranial pressure as a result of carbon dioxide retention Oxycodone (Roxicodone) 10 to 30 mg every 4 hours Often used in combination with acetaminophen, which limits safe dosage to 12 tablets per day (about 4 g of acetaminophen) Side effects: similar to those of codeine IM = intramuscular; IV = intravenous; SC = subcutaneous. *—Single-dose studies determined that the relative potency is 6:1; with repetitive doses, this ratio changes to 3:1.
Pain Management Equianalgesic dosages Usual starting dosage in adultsDrug Oral/IM potency IM Oral Oral ParenteralMorphine 6* 10 mg 60 mg 15 to 30 mg every 0.1 to 0.15 mg per(Duramorph) 4 hours kg every 3 or 4 hoursHydromorphone 5 1.5 mg 7.5 mg 2 to 4 mg every 4 1 to 2 mg every 4(Dilaudid-Hp) to 6 hours to 6 hoursMeperidine 4 75 mg 300 mg 50 to 150 mg 75 to 100 mg(Demerol) every 3 or 4 hours every 3 or 4 hoursLevorphanol 2 2 mg 4 mg 2 to 4 mg every 6 Up to 1 mg IV(Levo-Dromoran) to 8 hours every 3 to 6 hours; 1 to 2 mg IM or SC every 6 to 8 hours IM = intramuscular; IV = intravenous; SC = subcutaneous. *—Single-dose studies determined that the relative potency is 6:1; with repetitive doses, this ratio changes to 3:1.
Pain Validation• Pain scale—subjective• CT*• Chest X-Ray* *Not ordered regularly—very expensiveNeed: A reliable, non-invasive, and inexpensive deviceto provide correlating data between the occurance andseverity of vaso-occlusion and the pain that the patientis experiencing
Specifications• Vaso-occlusion reduces the flow of oxygenated blood, which leads to a reduction of oxygen within the tissue.• Reduced oxygenation leads to tissue damage and pain.• The device proposed will adapt the principles of photoplethysmography to measure the oxygen saturation level at the site of pain.
SpecificationsProduct Specification Design Specification Pulse oximetry will be used to detect the varying levels of1. Detecting varying levels of blood oxygen blood oxygen saturation. This must be able to read blood saturation oxygen saturation between 70% and 100% (ISO). The device will be able to detect a fraction of the light that2. The device must be able to obtain is originally emitted into the arm. The fraction will be measurements through 5 inches of flesh determined using Beer’s Law and the optical properties of human tissue. No exposed wires will be present in the device, and the3. Electrical components must be isolated leakage current will meet IEC standards (under 300µA). This includes the time taken to attach the device to the patient, the time required for the device to take4. Data acquisition must take less than 5 minutes measurements, and the time for the device to interpret the measurements taken This device must be reliable with no false negatives. This5. Reliability will follow ISO Standard 80601-2-61-2011. The device should not cause any discomfort during use. It6. Comfort/Ease of Use should be easy to place on the patient and should be easily removed
Alternative Methods Method Specifications Met Pros Cons Non-invasive May be time consuming to find the exact location of the vaso-occlusion Pulse Oximetry All inexpensive If the occlusion is too great, a signal may not be easily adaptable for our use determined Non-invasive All May be time consuming to find the exact Perfusion Index location of the vaso-occlusion inexpensive Expensive (Camera > $5002) Non-invasive Fast Frame 1,3 “SpO2 Camera”1 Only measures O2 at surface Non-invasive Expensive (Camera>$10003) Gives a general view of temperature in the Only measures temperature at surface Thermal Imaging 1,3 body Can only work if vaso-occlusion causes a Fast data acquisition temperature difference in skinSources: 1(Kamshillin 996-1006); 2EdmundOptics.com; 3Neo-Bits.com
Further ResearchFurther research is needed in the following areas:• Pathology of vaso-occlusion• Location of vaso-occlusion• Frequency of vaso-occlusion• Size of affected area• Time in which ischemia occurs• Treatments for vaso-occlusion (not pain treatment)
Specific Aims1. Confirm that a Vaso-Occlusive Crisis Can be Detected – Blood Oxygen Saturation – Pulse Oximetry – Photoplethysmography
Specific Aims2. Develop a Device that Can Measure the Varying Oxygenation Levels – The device will be developed using various programming software and hardware –LabView –LEDs –Photodetector
Specific Aims3. Design the Device so that it can be Attached to a Patient’s Arm of Varying Sizes – This device should be able to adjust to varying thicknesses. –Adjustable armband
Specific Aims4. Find a Correlation Between Oxygen Saturation in the Blood and Pain – A pain scale can be created that ranges from one to ten. – Each number on the pain scale can correlate to a specific range of oxygen saturation levels.
Preliminary Results (Figure 1adopted from Ahmed et. al.)
Preliminary Data• Methods of Data Collection – Vaso-occlusive crisis was simulated • A tourniquet was used to do this – Different pulse oximeters were used • Nano Tracker • Medtronic Lifepak 12 Clinical Pulse Oximeter • AD Instruments MLT321 Pulse Oximeters
Preliminary Data Table 1 - DATA FROM PHOTOPLETHYSMOGRAPH (NANO TRACKER) Normal O2 Normal O2 O2--V-O Mimic O2--V-O Mimic Left Arm Right Arm Left RightSubject 1 n/a 0.93 n/a 0.74Subject 2 0.95 0.97 0.76 0.8Subject 3 0.97 0.97 0.78 0.82STDV L 0.11030 STDV R 0.09786 n=2 p=0.0035 - Right Arm n=3 p=0.0055 - Left Arm
Preliminary Data Table 2 - DATA FROM MEDTRONIC LIFEPAK 12 PULSE OX Normal O2 Left O2--V-O Mimic Perfusion Index Arm LeftSubject 1 0.97 0.86 DecreasedSubject 2 0.96 0.88 No ChangeSubject 3 0.98 0.88 DecreasedSTDV 0.053821 p=0.0004 n=3
Preliminary Data Table 3 - DATA FROM AD INSTRUMENTS PULSE OX O2 Experimental Normal O2 Arm O2--Experimental (Normal Control Arm Conditions)Subject 1 0.97 0.97 0.92Subject 2 0.95 0.96 0.91Subject 3 0.974 0.983 0.953Subject 4 0.99 0.99 0.96 p=0.0540—Control vs. ExperimentalSTDV Exp 0.028116 p=0.0285—Experimental (Normal Conditions) vs. n=4 Experimental Conditions
Preliminary Data• T-test Values – Table 1 • p=0.0035 - Right Arm • p=0.0055 - Left Arm – Table 2 • p = 0.0004 – Table 3 • p = 0.054 – Control vs. Experimental • p = 0.0285 – Experimental (Normal Conditions) vs. Experimental Conditions
Purpose• Detect Low oxygen concentration in extremities.• Easy and cheap diagnostic technique for vaso- occlusion patient.• Early diagnosis ease the treatment and prevent further damage.
Working Principle• Pulse Oxymetry consist of Red(R) and infra red (IR) light emitting LEDs and a photo detector/s.• Oxygenated and de-oxygenated hemoglobin have differential light absorption rate. – Oxygenated hemoglobin absorbs more infrared light and deoxygenated hemoglobin absorbs more red light.• Photo detector measures the transmitted lights and calculate R/IR ratio.• R/IR ratio determines the oxygen blood concentration.
Modification• The pulse Oxymetry will be modified to fit inthe extremities.• High power LEDs will be used for larger parts.• Two oximeters will be used for control andexperimental data.• Multi-array detector will be used if needed
Proposed Solution• Single source multiple detector can beused.• Uneven distribution on the detector canbe analyzed mathematically.• The output in the detector can beaveraged out to find the occlusion.• Non-linear transmission of the light canresult the uniform result.• Experiment can be conducted to test thelinear behavior of the device.
Proposed Solution• Rotating LEDs with aligneddetectors can be designed.• Signal from detector can bereconstructed using convolution.• Complicated design but it canbe promising solution.• CT scan uses same mechanismto create the cross sectional area.
Testing• The device has to be calibrated for eachindividual.• The device uses its data and compares withthe control data.• Device will correlate the severity of the vaso-occlusion measuring the blood oxygenconcentration.
Design Specification• Our devicewill utilize anadjustable arm-band design.• We will usemultiple LEDsand detectors
Benefits of a Multiple LED system• Produces more light which allows detector to see dark spots better• Even if the crisis occurs outside of the emitance of the LED, our detectors can identify a crisis
Technique• We will use two pulse oximeters• This can allow us to get a baseline reading while simultaneously attempting to identify a crisis• Preliminary testing has proven this method to be viable
Recreating a vaso-occlusion• Vaso-occlusion causes less blood to reach tissue• We were able to slow blood flow to the extremities using a sphygmomanometer