Self-Regulating Oxygen Delivery System

1
Self-Regulating Oxygen Delivery System

• Lauren Ehardt
• Katelyn Klein
• Jason Nixon

Advisors Dr. Debatosh Debnath Dr. Cheryl
Riley-Doucet
2
Outline

• Introduction
• Problem
• Goals
• Background
• Benefits of
• Automatic Control System
• Design
• Future Plans

3
Introduction

• Supplemental oxygen is one of the most widely
  used therapies for people admitted to the
  hospital
• One million COPD patients in US
• Manual oxygen control is the norm

NHLBI, 2006
Who is this?
4
Need for Automatic Control

• No device exists to automatically regulate oxygen
  flow to a patient

5
Neonatal Environment

• Manual control of oxygen delivery
• Patient to nurse ratio is high
• Lack of awareness effects of hyper-oxygenation

Firestone, 2007
http//news.thomasnet.com/images/large/498/498329.
jpg
6
Outpatient Setting

• Difficult to prescribe oxygen flow rates
• Oxygen levels vary
• Activity level
• Environment
• No set standard to determine oxygen flow rate

Pilling, 1999
Guyatt, 2000
7
Project Goals

• Design a self-regulating device
• Control oxygen flow based on SpO2 readings
• Automatically adjust valve opening based on pulse
  oximeter signal

8
Project Goals (contd.)

• Device features
• Safe
• Reliable
• Easy to use
• Customizable
• Portable
• Cost-effective

9
Oxygen Therapy Background

• Oxygen saturation
• Oxygen therapy patients
• Hyper-oxygenation
• Mechanisms of oxygen therapy
• Current research

10
Oxygen Saturation of Blood

• Why do we need oxygen?
• Measured as percentage

Oxygen Saturation of Arterial Blood SaO2 true
oxygen saturation SpO2 measured by pulse
oximeter

• Normal adult SaO2 97-99
• Hypo-oxygenation SaO2 lt 90
• Normal infant SaO2 86-92

Schutz, 2001
Woods, 2005
11
Oxygen Therapy Patients

• Adults suffering from respiratory failure
• Chronic obstructive pulmonary disease (COPD)
• Pneumonia
• Asthma
• Treatment Long term oxygen therapy (LTOT)
• Neonates
• Supplemental oxygen is most common form of
  therapy

Pilling, 1999
12
Hyper-oxygenation

• CO2 retention
• Neonates
• Lung toxicity
• Brain toxicity
• Retinopathy of
• prematurity (ROP)

Mack, 2006
www.cartage.org.lb/.../humrespsys4.gif
13
Stevie Wonder
Suffered from Retinopathy of Prematurity
14
Mechanisms of Oxygen Therapy

• Low flow delivery systems (0-15 lpm)
• Variable performance
• Nasal canulla and face masks
• High flow delivery systems (gt15 lpm)
• Fixed performance
• For respiratory assistance in
• addition to supplemental oxygen

McGloin, 2007
www.jsdobbs.ie/jsdobbs/Main/Products_Oxygen.htm
15
Mechanisms of Oxygen Therapy (contd.)

• Three oxygen sources
• Liquid Oxygen
• Oxygen Cylinder
• Oxygen Concentrator

http//www.waldosworld.org/gallery03/oxygentank.jp
g
sunzi1.lib.hku.hk/hkjo/view/21/2100807.pdf
16
Mechanisms of Oxygen Therapy (contd.)

• Oxygen flowmeter
• Controls oxygen flow rate
• Oxygen blender
• Controls oxygen concentration and flow rate
• Mixes oxygen and air

http//www.gehealthcare.com/usen/suction_oxygen/ox
ygen_therapy/images/blender_c_l.jpg
17
Mechanisms of Oxygen Therapy (contd.)

• Measuring oxygen saturation
• Pulse oximetry
• Non-invasive
• Oximeters use alarms

www.medisave.co.uk/images/nonin-3100-pulse.jpg
Kamat, 2002
18
Current Research

• Columbia Life Systems
• SmartBlender http//smartblender.com/index.html
  
• Saturation Driven Oxygen Therapy (SDOT)
• Computer simulation shows automatic control is
  more effective in maintaining constant SpO2 than
  manual control
• Hospitals are switching to oxygen blenders

Iobbi, 2007
19
Benefits of Automatic Control

• Automatic adjustment of oxygen delivery
• Increases amount of time patients spend in
  desired SpO2 range
• Decreases hypo-oxygenation events

Zhu, 2005
20
Benefits (contd.)

• Avoid fluctuations in SpO2
• Prevent severe ROP
• Improve quality of care
• Lessen nurse workload
• Fewer alarms
• Prevent inappropriate action to reduce alarms

Zoidis, 2007
21
Project Design
22
HCS12 Microcontroller

• Program in C
• Runs up to 25 MHz
• Pulse width modulation (PWM) controls current to
  the proportional valve
• Serial communication interface (SCI) receives
  data from pulse oximetry board

23
Pulse Oximeter Sensor

• Two LEDs emit red and infrared wavelengths of
  light through skin
• Hb absorbs red wavelengths
• HbO2 absorbs infrared wavelengths
• Photodetector on other side picks up intensity of
  transmitted light
• SpO2 is calculated by analyzing received light
• Utilizes cardiac pulse to distinguish arterial
  blood from other mediums

Hb hemoglobin not bound to oxygen HbO2
hemoglobin bound to oxygen
24
Pulse Oximetry Board
BCI OEM 31392B1 Board

• Low power
• Data outputs SpO2 and pulse rate
• Eight second average (or
• instantaneous)
• Serial communication

25
Parker Proportional Valve
Parker Valve

• Controls the flow based on input voltage
• PWM generates variable input voltage
• Oxygen safe

26
Project Design
27
Cost Analysis
Blenders cost 1000
Project Total 352
28
Progress

• Literature reviews
• 50 research articles
• Visited respiratory therapist at Crittenton
  Hospital
• Researched valves and oximeter boards from many
  manufacturers
• Finished introduction of paper
• Started learning HCS12 modules

29
Progress (contd.)

• Received valve
• Received oximeter board
• Purchased oxygen tubing from Crittenton Medical
  Equipment store
• Flow meter from Binsons
• Purchased helium tank
• Continue learning HCS12 modules

30
Prototype
31
Final Goals

• Working prototype by July 16th
• Finish paper
• Create poster

32
Acknowledgement

• We thank Kristen Munyan of Beaumont Hospital for
  introducing us to the problem and Steve Yax of
  Crittenton Hospital Medical Center for answering
  our questions on respiratory equipment. This work
  was supported in part by the Bioengineering and
  Bioinformatics Summer Institutes Program of the
  National Institutes of Health and the National
  Science Foundation under grant 0609152.

33
References

• T. Croxton, HLBI and CMS launch large study of
  home oxygen therapy for COPD, NIH News, NHLBI
  Communications Office, 2006.
• K. Firestone and H. Adams, Evidence-based oxygen
  therapy for very low birth weight infants,
  Journal of Pediatric Nursing, vol. 22, no. 2, p.
  145, 2007.
• G. H. Guyatt, et al., Appropriateness of
  domiciliary oxygen delivery, Chest, vol. 118,
  pp. 1303-1308, 2000.
• D. L. Woods, Newborn care manual, Unit 26,
  International Association for Maternal and
  Neonatal Health, 2005.
• J. Pilling and M. Cutaia, Ambulatory oximetry
  monitoring in patients with severe COPD A
  preliminary study, Chest, vol. 116, pp. 314-321,
  1999.
• E. Mack, Oxygen administration in the neonate,
  Newborn and Infant Nursing Reviews, vol. 6, no.
  2, pp. 63-672, 006.
• S. L. Schutz, Oxygen saturation monitoring by
  pulse oximetry, AACN Procedure Manual for
  Critical Care, vol. 4, pp 77-82, 2001.

34
References (continued)

• Z. Zhu, et al., Continuous oxygen monitoring-
  better way to prescribe long-term oxygen
  therapy, Respiratory Medicine, vol. 99, pp.
  13861392, 2005.
• S. McGloin, Administration of oxygen therapy,
  Nursing Standard, vol. 22, no. 21, pp. 46-48,
  2008.
• V. Kamat, Pulse oximetry, Indian Journal of
  Anaesthesia, vol. 46, no. 4, pp. 261-268, 2002.
• M. G. Iobbi, A. K. Simonds, and R. J. Dickinson,
  Oximetry feedback flow control simulation for
  oxygen therapy, Journal of Clinical Monitoring
  and Computing, vol. 21, pp. 115123, 2007.
• D. Zoidis, Retinopathy of prematurity latest
  evidence regarding the use of supplemental
  oxygen, RT for Decision Makers in Respiratory
  Care, vol. 20, no. 1, pp. 20-22, 2007.