University of Pittsburgh Senior Design – BioE 1160-1161 Incubator Designed for Emerging Areas (iDEA) Ted Kastenhuber Bradley H. Morneweck Bailey M. Roche Christopher E. Withers Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Overview • Infant Mortality in Developing Countries • 98% of reported neonatal deaths occur in the developing world • One of the leading causes is failure to keep babies warm, which leads to increased hypothermia, decreased metabolism and infection Zupan, Jelka “Perinatal Mortality in Developing Countries”, N ENGL J MED 352;20. 2005. 2047-2048 Overview • Project contact: Dr. Ian Rawson, Hôpital Albert Schweitzer in Haiti • Hospital requires a low-cost, lowmaintenance neonatal incubator relevant to hospital situation • Projected intended to be a simple re-design of well-established incubation methods Infant mortality: 73 of 1,000 http://www.hashaiti.org/ Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Project Objectives • Design functioning neonatal incubator • Must be under $500 • Temporarily/semi-permanently operable outside of a variety of power grids • Carry out four functions in accordance with FDA standards • Thermoregulated heating • Appropriate humidity maintenance • Adequate ventilation maintenance • Maintenance of sterility Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Features & Benefits • Thermoregulated System with alarm means that busy clinicians can go about their tasks assured that infant is safe • Simple interface ensures that minimal training is required for operation • Low cost/accessible parts enable the device to be maintained on-site • Compatibility with independent power supply ensures that device may be operable under conditions with limited or unreliable power supply Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Competitive Analysis • Modern Incubators (Dräger Medical) • Extremely complex • Very expensive • Require extensive maintenance by highly-trained technicians http://www.gehealthcare.com/usen/perinatal/micro_environments/giraffe/images/giraffe_ph_prod_l.jpg http://www.hebi-incubator.org http://www-conference.slu.se/KMCeurope08/bilder/Ylvasfoto5.jpg Prasanga et. al., 2002 Competitive Analysis • HEBI + + - Cheap (€325 ~$510) Easy to use Difficult to set up No fine temperature control • Kangaroo Mother Care (KMC) + Cheap (free) + Easy - Cumbersome - Possibility of disease transmittal • Phase Change Passive Incubator (PCPI) + Lightweight - Actual development is very meager * Senior design project at MIT Competitive Analysis Parameter Cheap User Friendly Meets Modern Standards Requires Less Nurse Attention Safe Baby Accessible for Procedures HEBI KMC PCPI iDEA Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Quality System Considerations • Risk analysis • Significant risks • Electrical failure causing fire • Loss of 1o C heat precision • Air infection • Loss of airflow • General system responses • Failsafe systems respond • Alarm sounds • Device powers down (sounding alarm) Regulatory Considerations • Class II • FDA regulation 21 CFR 880.5400 – previous incubators designated class II • Also regulation: IEC 60601-2-19 1996-10: Amendment 1 - Medical electrical equipment Part 2: Particular requirements for safety of baby incubators, which pertains to the 510(k) specifics. • Third world application, bypasses FDA Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Our Design • Adequate Warmth • Adequate Humidity • Infant Visibility • Infant Accessibility • Air Filtration • Sterility Maintenance Our Design Thermoregulation Unit Surgical Mask Filtration Access Ports 12V Battery (Thermoregulation unit dedicated) Humidity Chamber and Power Supply Housing Temperature Chart1 12V Battery 1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007. Bassinet Access and Visibility • Access Ports • Sliding platform • Transparent faces Power AC DC Autocraft 12V Marine/RV Deep Cycle battery (Supplied by HAS) ePOWER EP-520XP-C1B ATX12V 520W Power Supply (x2) 9 V Battery for independent alarm circuit Heat Rally 12V Heater (200W) $5.99 CE PTC Ceramic Heater & Fan (300W) $25.00 Circuit MaxxTronic – MX052 – Digital Thermoregulator $39.95 Alarm Circuit1 -- $1.00 1. Stetten, George. "Comparators, Photoresistor, Thermoregulation, Hysteresis." University of Pittsburgh. Benedum Hall, Pittsburgh. 6 Apr. 2008 <http://www.stetten.com>. Humidifier PC fan ~$7.99 ea. Oven Pan $5.00 Ventilation 12V CoolerMaster computer fan (x2) Active outtake, passive intake Cost Analysis Material Cost (USD) Wood 75 Plexiglass 40 Hardware 50 Power supplies 70 PC fans 10 Heaters 31 Maxtronic Thermoregulatory circuit 40 Misc. electronic supplies 70 Caulk, sealant, etc. 20 Bulb Thermometer 31 Water pan 5 Total 442* *Note: The above prices reflect prototype production. During mass production, unit prices will be markedly lower. Cost Analysis $442.00 $510.22 $40,0001 HEBI iDEA Dräger 1. Kloesz, Jennifer L. Personal interview. 6 Oct. 2007. User input • Set point temperature • On/off • Battery or AC power • Alarm circuit on/off Outline • • • • • • • Overview Project Objectives Features & Benefits Competitive Analysis Quality System Considerations Regulatory Considerations Our Design • Considerations • Development • Verification & Validation Thermoregulation *Note: Resolution of data logger is 0.5°C. (set point = 37.0°C) Thermoregulation • Initial tests indicate that servo control is possible Humidity Relative Humidity over Time 80.00% Red Squares -- starting water temp = 52 deg C 75.00% Relative Humidity (%) 70.00% Blue Diamonds -- starting water temp = 30 deg C 65.00% Green Triangles -- included water heater 60.00% 55.00% 50.00% 45.00% 40.00% 35.00% 30.00% 0 10 20 30 Time (min) 40 50 60 Ventilation Ethanol Candle Test 14.335 g / 30 minutes = 232.7 mL O2/min A baby requires 2.48 mL O2/min* Oxygen requirements of candle exceed neonate by nearly 100, thus validating ventilation *Libert JP, Bach V, Farges G. 1997. Neutral temperature range in incubators: performance of equipment in current use and new developments. Crit Rev Biomed Eng 25(4-5):287-370. Sterility • Swabbed for bacterial growth • Time points: t0 = after ethanol cleansing; tF = after 5 hour run • Positive control outside • Swabbed • Inside bassinet • Inside humidity bay • Inside water pan Sterility t0 = right after cleaning with ethanol + Control Humidity Bay Water Pan Bassinet tF = after 5 hours of running incubator + Control Humidity Bay Water Pan Bassinet Clinician Feedback • Initial Impressions • Received well by Dr. Mahmood, MageeWomen’s Hospital • “I could see this device in my part of the world being used” • Survey: • Scale 1-5: • Ease of use, Utility, Safety Survey Ease of Use 1 2 3 4 Responsiveness 1 2 3 3.67 4 Mechanical Operability 1 2 3 4 Ergonomic and Aesthetic Quality 1 2 3 4 Three participants of backgrounds: 1. MD, Neonatologist fellow 2. High school equivalent 3. B.S., Bioengineering 4.67 5 5 4.67 4.33 5 5 Project Management Dec Jan Feb Mar Apr 3D Design Heating/Humidity element design Alarm Circuitry Device assembly Verification/ Validation Send to Haiti Each group member contributed equally to each aspect of the design process Comparison to PDS • Cost less than $500 • Must regulate temperature at set points 29-35˚ C • Must alert staff if the temperature falls out of range • Patient must be visible in the device Comparison to PDS • Noise < 47 dB (via Audacity™) • Dimensions < (2m x 2m x 2m) • Access to infant in less than 5s • Easily portable • Humidity > 40% Moving Forward • Immediate (Through April) • Come up with production plan • Long term (Early June?) • Create final product (kit) • Send and install device in HAS Acknowledgements • • • • • • • Ian Rawson, MD Burhan Mahmood, MD Jack Patzer, PhD Rich Stoner Andy Alexander Shawn Burton Sources of funding • Generous gift of Drs. Hal Wrigley and Linda Baker • Department of Bioengineering • NCIIA BMEidea stipend award ? Failure Mode Effect Analysis Function or Component Failure Mode Effect on System Hazard Risk Index Acceptance Criteria 1 to 5 Unacceptable 6 to 9 Undesirable 10 to 16 Acceptable upon completion of quality assurance review 17 to20 Acceptable without review Possible Hazards Risk Index User Detection Means Applicable Controls Electrical thermoregulation unit Incomplete/short circuit, thermistor malfunction Temperature of the system deviates from set value Over or underheating of the infant, dehydration; shock from circuit itself 10 Monitoring of temperature shows system is not being moderated adequately; alarm sounds Utilize circuit components with low voltage demands Electrical thermosensitive alarm unit Incomplete/short circuit, thermistor malfunction; incorrect input to alarm Alarm fails Infant remains in an over or under-heated state for an amount of time that is fatal 10 Monitoring of system shows temperature reads too high or low and no alarm has sounded Utilize circuit components with low voltage demands; provide detailed, clear schematics for repair Auditory Alarm Burnout or loss of function Alarm fails to sound in the event of large deviation from set value Infant remains in an over or under-heated state for an amount of time that is fatal 15 Monitoring of system shows temperature reads too high or low and no alarm has sounded Provide instructions for replacement; recommend regular tests Table & legs Failure to provide adequate support Device falls unexpectedly Trauma to infant 12 Visual observation. Ensure that device platform is structurally sound, provide warnings for incubator placement Box/insulation component Insufficient capacity to retain heat; puncture Device is unable to reach set temperature value Infant temperature too low, hypothermia 14 Alarm sounds. Warnings and detailed instructions for leak repair Doors and hinges Unable to easily open Infant trapped inside of incubator Asphyxiation, overheating, dehydration of infant 17 The door resists opening. Enable hinges to be manually detached, provide warnings for proper handling of doors + hinges; recommend regular tests Holes Occlusion Air ceases to be able to pass through device Oxygen depletion, asphyxiation of infant 12 Visual inspection of occlusion, unable to feel air flow placing hand over the hole Ensure hole diameters are at a value that minimizes both occlusion occurrence and heat loss Fan Mechanical failure, circuit failure Air ceases to be pushed through device Overheating of infant, oxygen depletion, asphyxiation 14 Visual or auditory recognition of fan failure Heating lamps/bulbs Burnout, improper connection Air ceases to be heated Hypothermia; shock, burns, broken glass hazards 9 Visual recognition or alarm sounds. Ensure fan component is easily replaceable, provide warnings for use Use low wattage light bulbs; suggest having readily available back-up; use shatter-proof spotlight. Redesigns • Bassinet • Plexiglas vs. wood • Added features • Humidifier • Simple • Capillary action • Enclosed pan • Open chamber with forced air Redesigns • Thermoregulation circuit • Op Amp comparator • PIC controller • MaxxTronic • Alarm Circuit • Data logger • Op Amp Comparator