医疗器械培训资料：Masimo - Fundamentals and MasimoSET

1、3/2009 Masimo User Training China, August 27-28th 2009 Angela Teh Clinical Specialist, APAC 2009 Masimo Corporation 3/2009 Conventional Pulse Oximetry 2009 Masimo Corporation3/2009 Learning Objectives Upon completing this course the participant will be able to: Describe the basic operating principle

2、s and the four key assumptions of conventional pulse oximetry Define the common failure modes of conventional pulse oximetry Define the signal to noise ratio and indicate an optimum condition List five common sources of noise that can corrupt a pulse oximeter signal 2009 Masimo Corporation 3/2009 Ba

3、sics of Pulse Oximetry 2009 Masimo Corporation3/2009 Basics of Pulse Oximetry Pulse Oximeter Components Photodetector SENSOR Monitor - analyzes signal and reports SpO2 and pulse rate MONITOR IR R Patient cable - transmits signal to the monitor CABLE Emitter - shines Red (R) 79: 248-54. Malpositioned

4、 N-100 sensor vs. N-200 control, 12 subjects Malpositioned Sensors Dont Operate Within Calibration Data 2009 Masimo Corporation3/2009 Calibration Data AssumptionImpact if Not True Good alignment, light goes through site (digit) not around site More or less light than on calibration test subjects get

5、s from emitter to detector (“Penumbra effect”) Normal shaped digit, euvolemia Optical path length different than in calibration test subjects Consistent coupling of detector to skinLess light than on calibration test subjects gets from emitter to detector Nothing blocking sensor light path, i.e. dir

6、t, blood or metallic fingernail polish Less light than on calibration test subjects gets from emitter to detector Patient has normal hemoglobin levelsAll empirical calibration test subjects had normal hemoglobin levels Reasonable amount of ambient lightHigh ambient light (noise) may overwhelm red li

7、ght to detector Only one sensor used at a time and detector picks up light from only its emitter Two sensors next to each other can cause cross talk and erratic readings Failure Modes of Assumption #2: One Experimental Calibration Fits All 2009 Masimo Corporation3/2009 Correct Backwards and malposit

8、ioned 2009 Masimo Corporation3/2009 L 3rd digit sensor not only backwards, but badly aligned “penumbra effect.” Well-described in literature, often produces SpO2 readings of 85- 92% on all pulse oximeters Pleth waverform and signal quality indicators do not reliably detect penumbra- user must apply

9、the sensor properly. Case Study Analysis 2009 Masimo Corporation3/2009 Common sources of noise include: Signal: Pulsatile Red/Infrared Noise: unwanted signal that interferes with the red/infrared signal from the emitter. Signal and Noise (electrocautery) (surgery or biliruben lights) (decoupling fro

10、m patient) (triboelectric) (patient movement) Increasing perfusion = increasing signal strength 2009 Masimo Corporation3/2009 Important Concept: Signal To Noise Ratio Higher Values = Better Performance Low signal to noise ratio High signal to noise ratio 2009 Masimo Corporation3/2009 High Perfusion

11、High Noise Conventional Pulse Oximeters Require Fairly Strong Perfusion to Read Signal Through the Noise Low Perfusion High Noise 2009 Masimo Corporation3/2009 1.The only absorbance that fluctuates is arterial blood 2.One experimental calibration fits all No anemia Nothing blocking sensor light path

12、, i.e. dirt, blood, metallic fingernail polish No bright external light sources Correct size sensor on appropriate site with good alignment Correct digit shape- no “clubbed digit” or swelling from hypervolemia Emitter light goes through digit not around digit, no penumbra effect 3.Only two variable

13、light absorbers- oxyhemoglobin and reduced hemoglobin No dyshemoglobins 4.The sampled and measured sites are in equilibrium. Reasonably good perfusion at monitoring site No localized hypoxemia Four Key Assumptions in Conventional Pulse Oximetry 2009 Masimo Corporation3/2009 Barker SJ, Tremper KK, Hy

14、att J. Effects of Methemoglobinemia on Pulse Oximetry and Mixed Venous Oximetry. Anesthesiology 1989;70:112-117 Blood 2 wavelength Pulse Oximeter Laboratory CO-Oximeter Blood Sample High Methemoglobin Reads 85% On Two Wavelength Pulse Oximeters 2009 Masimo Corporation 3/2009 Rainbow Signal Extractio

15、n Technology Pulse Oximetry Assumption: HbO2 and RHb are the only variable light absorbers 2009 Masimo Corporation3/2009 Barker SJ, Tremper KK. The Effect of Carbon Monoxide Inhalation on Pulse Oximetry and Transcutaneous PO2. Anesthesiology 1987; 66:677-679 Blood 2 wavelength Pulse Oximeter Laborat

16、ory CO-Oximeter Blood Sample High Carboxyhemoglobin Reads 90% On Two Wavelength Pulse Oximeters 2009 Masimo Corporation3/2009 1.The only absorbance that fluctuates is arterial blood 2.One experimental calibration fits all No anemia Nothing blocking sensor light path, i.e. dirt, blood, metallic finge

17、rnail polish No bright external light sources Correct size sensor on appropriate site with good alignment Correct digit shape- no “clubbed digit” or swelling from hypervolemia Emitter light goes through digit not around digit, no penumbra effect 3.Only two variable light absorbers- oxyhemoglobin and

18、 reduced hemoglobin No dyshemoglobins 4.The sampled and measured sites are in equilibrium. Reasonably good perfusion at monitoring site No localized hypoxemia Four Key Assumptions in Conventional Pulse Oximetry 2009 Masimo Corporation 3/2009 Differences in Measured Values Measured Site- Pulse Oximet

19、ry Sampled Site- ABG CO-oximetry 2009 Masimo Corporation3/2009 Localized Hypoxemia SpO2 reading in a poorly perfused extremity is significantly less than the SaO2 determined by an ABG May be associated with: Significantly increased peripheral vascular resistance Peripheral vascular disease or Multip

20、le pressors (e.g. Levophed) Severe hypovolemia Shock Results in circulatory (stagnant) hypoxemia in the extremity Localized lactic acidosis and CO2 accumulation secondary to poor perfusion shift the oxyhemoglobin disassociation to the right. 2009 Masimo Corporation3/2009 Motion: shivering, restless

21、patient, patient care Low perfusion: hypothermia, shock Electromagnetic interference: electrocautery Excessive ambient light: phototherapy, daylight, operating room lights Dyshemoglobins, anemia Conventional Pulse Oximetry Failure Modes Create False Alarms and Inaccurate Data 2009 Masimo Corporation

22、3/2009 Undetected Probe-Off In rare circumstances the pulse oximeter can continue to give erroneous readings within the normal physiological range during probe off Serious limitation of pulse oximetry No pulse oximetry manufacturer appears to be immune from the undetected probe-off condition Any pul

23、satile interference at the sensor can produce a false signal that could be interpreted by the pulse oximeter as a true physiological signal 2009 Masimo Corporation3/2009 Types of Signal Interference That Can Produce an Undetected Probe-Off Condition Most Common is Ambient Light Surgical lights, bili

24、rubin lights and infrared radiant warmers Light from the Emitter Emitted light reflected by colored fabrics that are positioned in or near the photo emitter - detector path can also produce an SpO2 reading that is artifactual. 2009 Masimo Corporation3/2009 Questions? 2009 Masimo Corporation 3/2009 M

25、asimo Signal Extraction Technology Pulse Oximetry 2009 Masimo Corporation3/2009 Learning Objectives Upon completing this course the participant will be able to: Describe which of the four key assumptions of conventional pulse oximetry apply to Masimo SET Describe the SET pulse oximeter system and it

26、s improvements versus conventional pulse oximetry systems Describe how SET reads during poor perfusion Describe the key differentiating features and benefits of Masimo SET including: Highest signal to noise ratio Parallel algorithms, including DST, and adaptive filters Multiple sensitivity settings

27、Signal IQ reads 10X smaller pulse amplitudes Motion Electrical Interference Light Patient cable improved design (extra shielding) shields from electrical and motion induced noise; transmits shielded signal to the monitor Masimo SET Improves Entire System Sensors, Cable, Software and Hardware 2009 Ma

28、simo Corporation3/2009 Masimo SETs Parallel Algorithms for SpO2 R/IR (Conventional Pulse Oximetry) Confidence Based Arbitrator 0 50% 66% 97% 100% Post Processor Digitized, Filtered otherwise the system would not display values at all Signal IQ spikes 2009 Masimo Corporation3/2009 Effect of Saturatio

29、n Averaging Time 16 Second Averaging Raw Data 2 Second Averaging Longer averaging = smoother data, desats dont look as deep 2009 Masimo Corporation3/2009 Multiple Averaging Time Options Masimo averaging options: 2, 4, 8, 10, 12, or 16 seconds Flexibility to suit each clinical area and application 20

30、09 Masimo Corporation3/2009 Different Clinical Areas Benefit from Different Averaging Times Sleep labs typically use fastest averaging for highest resolution- 2 seconds General floors typically use longer averaging times- 8 to 16 seconds Clinical Specialists work with customer to determine appropria

31、te averaging for each area/patient population 2009 Masimo Corporation3/2009 Only Masimo SET Offers User Selectable Device Sensitivity care areas where patients are observed frequently) lose direct observation of measurement site is suggested to detect sensor off conditions 2009 Masimo Corporation3/2

32、009 Device Sensitivity & Probe Off Detection 2009 Masimo Corporation3/2009 Sensitivity & Specificity Detect true events, not create false alarms Independent study comparing Masimo SET vs N600 and GEs “TruSat” technology1: Missed Event Sensitivity False Alarm Specificity Masimo SET1/40 97.5% 6/120 95

33、.0% Nellcor N60017/40 57.5% 34/120 71.5% GE-D/O TruSat 33/40 17.5% 21/120 82.5% 1 Nitin Shah, M.D., Laverne Estanol, M.S. Anesthesiology, 2006 Long Beach VA Medical Center, UC Irvine Medical Center, Long Beach, California Comparison of Three New Generation Pulse Oximeters During Motion and Low Perfu

34、sion in Volunteers All Pulse Oximeters have False Positive States False Alarms All Pulse Oximeters have False Negatives States Missed true desaturations Masimo SET has fewer false positives and fewer false negatives than other pulse oximetry technologies 2009 Masimo Corporation 3/2009 Tighter Data P

35、oints Mean Better Accuracy Masimo SpO2 accuracy: + 2% at 1 standard deviation (1 SD) Lab CO-Ox accuracy: + 1% 68% of data = 1 SD 95% of data = 2 SD 2009 Masimo Corporation3/2009 SpO2 reading Probability SET + Adtx Accuracy Claim is 2% What does it mean if SpO2 = 90%? Masimo SpO2 accuracy: + 2% at 1

36、standard deviation (1 SD) 2009 Masimo Corporation3/2009 Questions? 2009 Masimo Corporation 3/2009 Troubleshooting 2009 Masimo Corporation3/2009 Troubleshooting No readings Assess patient Verify sensor is plugged firmly into cable, into device, device powered on Replace sensor if: No red light from s

37、ensor emitter Improper sensor for patient weight Poor adhesion and coupling Reposition or relocate sensor if: Improper sensor location (e.g. no finger sensors on forehead or ear) Improper emitter and detector alignment Blood, dirt or metallic fingernail polish Shield sensor from any extremely bright light or another PO sensor Replace cable if: No red light from sensor across multiple sensors on same cable Red light from sensor, on well perfused site, but still no reading 2009 Masimo Corporation3/2009 Using Signal IQ and