Oxygen Control and Measure System Development Divia Patel, Angie Powe, Stacey Scheib Advisors: Dr. John Penn Dr. Paul King

Project Definition §The goal of this project is to design, build, and test a device that can monitor and control blood oxygen saturation levels. §To accomplish this goal we will obtain a unit to measure both FiO2 and SaO2. This unit will be combined with a unit and the code to measure respiration and heart rate. The obtained data will be analyzed to find a correlation.

Important Statistics §3800 children in US affected by ROP § will develop blindness §It is the only cause of early onset so economic implications are greater. §No visual memory which affects learning and quality of life. §1,100,000 legally blind people in US

Why care about infant retinopathy? §Retinopathy of prematurity, formerly called retrolental fibroplasia, is a developed disorder of the retina that prevents the eye from developing properly and can lead to permanent damage and blindness. §Survival Rates for infants under 1000g. §Early onset of blindness and its repercussions.

Cost Analysis §NICU cost among most expensive types of hospitalization §Improved monitoring results in better patient outcome and less time in hospital which leads to significant cost reductions l Median cost of treatment $49,457 with average stay of 49 days (varies inversely with birth weight) l Average cost of respiratory therapy $3112 with maximum value of $237,032

What causes retinopathy? §In premature infants, the normal growth of the retinal vessels stops, and abnormal new vessels begin to grow; this is usually associated with fluctuation in blood oxygen levels. Normal retinaThreshold ROP retina

Current Standard of Care §Infants are set on a monitor whose alarm sounds when oxygen levels extend beyond set boundaries. §Nurses must hear alarm and respond immediately, to manually adjust oxygen administration levels - leaving much room for variability. §Once infants reach pre-threshold level, doctors intervene to ablate periphery of retina (mainly for STOP-ROP).

Specific Problem & Our Solution §There is still vast fluctuations in the blood oxygen saturation levels despite monitoring and control with present methods. §Our solution creates a smart monitoring system of blood oxygen saturation levels that incorporates specific protocols to adjust delivery of oxygen.

Coefficient of Variation §Measured from blood gas analysis (PaO2) §Equals standard deviation /mean §In rat and human studies 1 st five days showed tight correlation and likelihood of infant progressing to threshold ROP (Penn, 1995).

What is our objective? §Design a smart monitoring and control system to minimize fluctuations in blood oxygen saturation levels.

Existing Patents similar to this Project §Adaptive control of neonatal fractional inspired oxygen (Taube, 1989). §Closed-loop non-invasive oxygen saturation control system (Raemer, 1994). §Patient data controlled respiratory system (Dragerwerk AG, 1982).

Action Plan § Current Status l Literature Research Performed l Established Contacts: Dr. Dan Lindstrom, Dr. Jackie York l Viewed timestamped SaO2 data from Dr. Lindstrom l Contacted Ohmeda & obtained oxycap monitoring unit - which came in and serial port not accessible so it was returned l A further monitoring unit is scheduled to arrive this week, as it was sent out Monday 3/20/00. l Data will be obtained and saved from this new unit by serial port connection.

Future Goals l Obtain timestamped FiO2, SaO2, respiratory rate, and heart rate data for analysis from unit to be obtained l Design and build smart monitoring and control unit l Get prototype breadboard and power supplies l Select optical sensor and A/D converter l Sketch tentative circuit and calculate circuit values l Build analog circuit, take in vitro measurements, and connect analog circuit to the A/D converter l Obtain oxygen sensor and oxygen blender

Future Implications §Exact standard of care between hospitals is different §ROP numbers are very conservative §Post-operative patients §Frees nurses time §Decrease NICU noise pollution §Severe Asthma Patients §Diving Equipment

Weekly Scheduled Meetings §All Group Members will work individually at their convenience. §Meet as a group:Weekly on Monday 7pm §Group Members meet with Dr. Penn Weekly on 12:00 p.m.

Highlight of Articles Read by Group Members & References §Fanconi, et al. Pulse oximetry in pediatric intensive care: Comparison with measured saturations and transcutaneous oxygen tension.The Journal of Pediatrics. §Deckardt, et al. Noninvasive arterial hemoglobin oxygen saturation versus transcutaneous oxygen tension monitoring in the preterm infant. Critical Care Medicine. §Morozoff, P.E., Evans, R.W. Closed-loop Control of SaO 2 in the Neonate. Biomedical Instrumentation & Technology. §Phelps,Dale L., Supplemental Therapeutic Oxygen for Prethreshold Retinopathy of Prematurity (STOP-ROP), A Randomized, Controlled Trial. Pediatrics. §Smith, et al. Automated End-Tidal CO2 Monitoring in the Postoperative Patient §Rogowski, J. Measuring the Cost of Neonatal and Perinatal Care. Pediatrics §Dr. John Penn, Vanderbilt University