Compliance Guide for AVOXimeter 1000E
Contents
1. 86 1939uTXOAV IL Multi 4 CO Oximeter Controls AVOXimeter 1000 Quality Control Level 2 Serial number THb g dl HbO2 Cuvette Pathlength Mo Yr 00 86 IL Multi 4 CO Oximeter Controls AVOXimeter 1000 Quality Control Level 1 Serial number THb g dl eHbO2 Lot number Cuvette Pathlength 88600 00066 00066 86 RNA CC 527 CO Oximeter Controls 1000E Quality Control Level 2 Serial number THb g dl2. HbO2 Lot number Cuvette Pathlength Mo Yr 86 1939uTxOAV
3. Test System Code and Name 04537 Systems AVOXimeter 1000 Analyte Code and Name 4604 Oxyhemoglobin Oxygen Saturation FDA 510 k Number 922075 Complexity MODERATE If the test system indicated above hag received clearance through the FDA 510 k or PMA process this complexity categorization is effective as of the date of this notification and this categorization information may be provided to the user of the test system assay examination as specified for the analyte indicated This determination will also be announced in a Federal Register Notice which will provide opportunity for comment on the decision CDC reserves the right to reevaluate and recategorize this test based on comments received in response to the Federal Register Notice It should be noted that a complexity categorization is based upon the unique combination of a test system and analyte therefore it cannot be assumed that the same categorization applies to other analytes determined on the test system indicated above The CDC Identifier Codes referenced above are unique identifiers developed by CDC to facilitate data management They can be used by CDC FDA the Health Care Financing Administration HCFA clinical laboratories and health insurers to track an assay s complexity Edward L Baker M D M P H Director Public Health Practice Program Office 14 AVOXimeter Compliance Guide Rev3 98 Quest Diagnostics Incorporated One Malcolm A
4. Chemistry Resource Committee Member cc Julie Richard MT ASCP CAP Jean Tenuta MS MT ASCP CAP Albert Rabinovitch M D Ph D CAP 15 THb g dl HbO2 MM DD YY bh 1000 E Yellow Filter Values Serial No 86 1939uTXOAV THb g dl HbO2 MM DD YY bh N AVOXimeter 1000 only Orange Filter Values Serial No 86 1939uTxOAV THb g dl HbO2 MM DD YY bh 1000E Orange Filter Values Serial No
5. AVOXimeter not to be affected by the partial or total hemolysis of the blood sample To restate the previously cited NCCLS document values for saturation obtained from instruments designed for trending or other simple oximeters must not be used for fur ther calculations such as shunt fraction or oxygen content since clinically significant errors can result NOTE Under no circumstances should a comparison be made between the results of a pulse oximeter and a whole blood oximeter Similarly compar ing a whole blood oximeter with the saturation calculated by a blood gas analyzer is a complete waste of time AVOXimeter Compliance Guide Rev3 98 IV A VOX QC PROGRAM The Quality Control OC Program for the AVOXimeter is as simple as the device is to operate It is comprised of two types of OC materials 1 the Optical QC filters yellow amp orange and 2 Aqueous CO Oximeter Controls Optical OC Filters Two optical filters are supplied with every AVOXimeter Each filter is marked with the serial number of the instrument for which it is intended and the range of acceptable values Do not use the filters from another instrument It is the recommendation of A VOX Systems Inc that you use these filters every day in which clinical samples will be tested These filters are treated just like a sample cuvette Insert the filters into the AVOXimeter In less than 10 seconds the results will be displayed on the scre
6. and reagents No equipment or reagents are required for routine use Ordinary syringes rinsed with heparin and AVOXimeter cuvettes are the only items required for the routine analysis of blood samples Commercial sources are given for quality control materials and for proficiency testing materials in the Operator s Manual or Section IV in this document Step by step procedure 1 To obtain accurate measurements collect blood samples in a heparinized plastic syringe 2 When drawing blood samples from a saline filled catheter withdraw the saline first and make sure that only whole blood is sampled Allowing the sample to be diluted with saline could possibly oxygenate the sample and will definitely induce dilution errors in the measurement of total hemoglobin 3 Keep each syringe containing a blood sample tightly sealed and roll the syringe between your palms to keep the red blood cells and plasma well mixed 4 To fill a cuvette attach a disposable cuvette to the Luer tip of the syringe Point the cuvette downward at a 45 angle and observe the sample chamber in the cuvette Press the plunger gently and fill the cuvette Stop injecting the sample as soon as blood reaches the air vent CAUTION Never force blood into the cuvettes If it does not flow easily discard that cuvette and use another one 5 Analyze each sample promptly The AVOXimeter can analyze 6 samples per minute so there is no need to store the samples before analyzing the
7. are actual hemoglo bin solutions and do require refrigeration These controls can be used to verify the calibra tion of the AVOXimeter and can be used in the re calibration procedure should this be come necessary The Multi 4 controls can be purchased directly from Instrumentation Laboratory by calling 800 955 9525 10 AVOXimeter Compliance Guide Rev3 98 Another manufacturer of aqueous controls is RNA Medical RNA CO Oximeter controls are dye solutions and do not require refrigeration however they can only be used for verification of calibration Should your AVOXimeter need to be recalibrated you will have to purchase IL Multi 4 controls RNA controls can be purchased from RNA Medical by calling 800 533 6162 It is the recommendation of A VOX Systems Inc that the verification of calibration by one aqueous control IL Level 2 or RNA Level 2 be per formed on a weekly basis NOTE Some institutions or state agencies may require two levels of aqueous control If this is the case A VOX Systems recommends using IL Levels 1 amp 2 or RNA Levels 1 amp 3 To perform this verification simply break open one of the ampules of control solution and withdraw 0 2 to 0 3 ml into a 1ml syringe Fill the cuvette as you would for a blood sample Insert the cuvette into the AVOXimeter In less than 10 seconds the results will be dis played on the screen Record these results on the appropriate OC Log sheet Each lot of aqu
8. met G Perform and document applicable specialty and subspecialty control procedures This section does not apply to the AVOXimeter H Perform and document remedial action taken when problems or errors are identified As an example should the QC filters indicate the instrument has become contaminated with blood it should be disassembled according to the directions in the Operator Service Manual Once the device is cleaned and reassembled the filters should be retested The unit should not be used to analyze patient samples until the filters provide results within the acceptable range specified Notations can be made on the QC filter log sheets to document this remedial action NOTE All records documenting the above procedures must be kept for two years AVOXimeter Compliance Guide Rev3 98 Who Can Perform the Test CLIA 88 also established a set of qualification requirements for the personnel who are authorized to perform moderately complex tests Each hospital will have at least one CLIA license holder It is your responsibility to notify this person and inform him her of your intent to perform the tests related to the AVOXimeter This could be the Director of Clinical Laboratories or the Point of Care Testing POCT Coordinator This person will review the qualifications of your personnel to determine if they satisfy the requirements of CFR 493 Subpart M What about Proficiency Testing Another provision of CLIA 88
9. poses of comparison between devices In addition most blood oximetry PT programs for ask for the results for total hemoglobin concentration THb not for O2Hb Entering the O2Hb data instead of the THb data is an example of the kind of error that has resulted in a laboratory s receiving a poor PT evaluation CAUTION Since THb data is being evaluated it is extremely important to have entered the correct pathlength for the cuvettes used during the test An incorrect pathlength will result in an error in the THb value Consult the Operator Service manual or the cuvette box insert for the directions on entering the correct pathlength AVOXimeter Compliance Guide Rev3 98 III OXIMETRY PRIMER O2 Saturation O2Sat what is it There is some confusion in the laboratory about the definition of Sat or SO 90 Functional Oxygen Saturation Functional oxygen saturation is the oxygenated hemoglobin divided by the sum of the oxygenated hemoglobin and the de oxygenated hemoglobin Carboxyhemglobin methemoglobin sulfhemoglobin or other dyshemoglobins are not part of the equation and as a result can introduce error if they are present Fractional Oxygen Saturation Fractional oxygen saturation is the fraction of the total hemoglobin that is oxygenated Fractional O Saturation is sometimes referred to as FO Hb In this equation all dyshemglobins are in the denominator see equation 4 page 2 Although the AVOXimeter 1000 does no
10. requires participation in Proficiency Testing for laboratories performing moderately complex tests CFR 493 Subpart H The Proficiency Testing PT program must be approved by HHS but more important they must have a survey that is appropriate for the device and the test performed Once you have selected a PT program you must notify HHS and authorize the PT provider to release your results to HHS You are prohibited from discussing your results with any other laboratory until after the survey results are published by the PT provider Your results must then be made available to the public as required in section 353 f 3 F of the Public Health Service Act Consult CFR 493 801 for more information regarding PT programs The College of American Pathologists CAP has a survey SO for Blood Oximetry They can be reached at 800 323 4040 The American Proficiency Institute APT also has a survey for Blood Oximetry Cat 114 94 and can be reached at 800 333 0958 This is not intended to be a complete list of Blood Oximetry surveys Please consult HCFA for a complete list of approved PT providers There are several common misconceptions about PT the first being that the surveys are designed to evaluate the device or the test process These surveys are in fact designed to evaluate the operator No conclusions regarding the accuracy or precision of your instru ment can be inferred from the survey results and results should not be used for the pur
11. 4 What Does This Mean CLIA 88 has established a set of requirements for Quality Control OC procedures that must be applied to each analytical test process your hospital laboratory performs These requirements published in detail in CFR 493 1202 1223 include A Follow the manufacturer s instructions for instrument or test system operation and test procedure B Provide adequate facilities and environment for conducting the services offered C Utilize test methods equipment instrumentation reagents materials and supplies that provide accurate and reliable test results D Have a procedures manual describing the processes for testing and reporting patient results Perform and document calibration procedures at least once every six months Perform and document control procedures using at least two levels of control materials each day of testing G Perform and document applicable specialty and subspecialty control proce dures as specified under CFR 493 1225 1271 H Perform and document remedial action taken when problems or errors are identified m mn A Follow Manufacturer s Instructions The Health Care Financing Administration HCFA and the Centers for Disease Control CDC have been assigned the task of reviewing the manufacturer s instruction to see if they fulfill the OC requirements of CLIA 88 To date no manufacturer s products have received this CLIA clearance 3 AVOXimeter Compliance Guide Rev3 98 On May 12 1
12. 997 these two agencies published a notice in the Federal Register postponing the effective date until July 31 1998 At this point if you follow the manufacturer s instruc tions for QC procedures you should be in compliance For updated information on this and other CLIA related issues visit the website maintained by the American Association of Clinical Chemists AACC Their website address is http NNwww aacc org For additional information on this service call Vince Stine at 800 892 1400 In some instances the requirements of an individual institution or state agency may exceed the manufacturer s recommendations In this case the requirements of the local authority will supercede For the manufacturer s recommended QC procedures for the AVOXimeter see page 10 B Provide Adequate Facilities and Environment Simply stated the laboratory must provide adequate space ventilation and utilities neces sary for conducting all phases of the testing This includes the posting of all safety precau tions to ensure protection from biohazards The AVOXimeter 1000 should be kept away from bright lights and drafts The power requirements depend on the model The AVOXimeter 1000E should be operated only with the transformer supplied by A VOX Systems Inc AVOXimeters should never be used in the presence of flammable anesthetics Standard Blood precautions should always be observed C Utilize Test Methods Equipment Instrumentation Reagents Material
13. AVOXimeter Compliance Guide Rev 3 98 Contents I Introduction 2 CLIA 88 3 Categorization 3 OC Requirements 3 Proficiency Testing 7 III Oximetry Primer 8 IV A VOX QC Program 10 V Procedures Manual 12 VI FDA Letter Complexity Level 14 VII Letter from CAP 15 VIII QC Log Sheets Yellow filter 1000 or E 16 Orange OC filter 1000 17 Orange OC filter 1000E 18 IL Multi 4 Level 2 19 IL Multi 4 Level 1 20 RNA CC 527 Level 2 21 xl AVOXimeter Compliance Guide Rev3 98 I INTRODUCTION The AVOXimeter 1000 quickly measures the oxyhemoglobin saturation Y HbO the total hemoglobin concentration THb and the oxygen content O c of a blood sample in a disposable cuvette Cardiac catheterization laboratories and intensive care units routinely use such measurements for two purposes 1 to detect intracardiac and great vessel shunts and 2 to compute cardiac output by the Fick Principle The AVOXimeter has no moving parts and requires almost no maintenance PRINCIPLE OF MEASUREMENT According to Beer s Law if several light absorbing compounds are present in a solution the concentration of each compound can be deduced if the compounds differ in their opti cal absorbances and if optical density is measured at as many wavelengths as there are compounds present For example if three compounds X Y and Z are present and if the optical density OD is measured at three different wavelengths the resu
14. Menu Then select Choice 3 on the Calibration Menu When you are prompted to do so give the AVOXimeter the pathlength value on the bag or box of cuvettes you are currently using e g 98 103 110 um etc After you confirm that the value you have entered is correct the instrument will then store a new calibration constant in non volatile memory and use it in subsequent analyses When you confirm that the new value for the cuvette pathlength is correct the AVOXimeter will return to the Calibration Menu Use the Cancel key to return to the sample analysis mode of operation CAUTION The oxyhemoglobin saturation HbO may also be calibrated according to the procedure outlined in the Operator s Manual but it is recommended that the user seek factory assistance before carrying out this procedure 13 AVOXimeter Compliance Guide Rev3 98 ot DEALT DEPARTMENT OF HEALTH amp HUMAN SERVICES Public Health Service low Centers for Disease Control and Prevention CDC Atlanta GA 30341 3724 August 18 1995 Categorization Notification Regulations codified at 42 CFR 493 17 implementing the Clinical Laboratory Improvement Amendments of 1988 require the Secretary to provide for the categorization of specific clinical laboratory test systems assays and examinations by level of complexity Based upon these regulations the following test system assay or examination for the analyte indicated is categorized below
15. boratory to perform and document calibration procedures at least once every six months There in some confusion in the wording of this statute Calibrat ing an instrument is not the same as confirming calibration A VOX Systems does not recommend that you calibrate an AVOXimeter that does not require recalibration The AVOXimeter has been proven to be very stable over long periods i e for years It should be sufficient to confirm that the AVOXimeter is still calibrated This is accomplished by the two fold approach to Systems The daily filters will be discussed in Section F A weekly check with liquid controls available from IL or RNA See page 10 will confirm that the AVOXimeter is calibrated It is the laboratory s resposibility to perform and document these checks Perform and Document Control Procedures As stated in Section E A VOX Systems provides the laboratory with two QC filters which should be used each day of clinical testing These filters serve two purposes First and most obvious is that they represent two levels of control material representing samples of two different concentrations They are not to be confused with electronic controls They test the functionality of the optical system A copy of a letter from Dr Kaufman member of the Chemistry Resource Committe of CAP is on page 15 He states that if we inter pret the two QC filters as samples of different concentration then the requirement for CLIA is
16. d the total hemoglobin concentration AVOXimeter Compliance Guide Rev3 98 II CLIA 88 The Clinical Laboratory Improvement Amendment of 1988 CLIA 88 was enacted by Congress to apply regulations to laboratories that examine human specimens for the diagnosis prevention or treatment of any disease or impairment of or the assessment of the health of human beings This regulation was published in the Federal Register 42 CFR 405 et al in its final form on February 28 1992 CLIA 88 established three categories of test systems The Certificate of Waiver was applied to test systems that 1 are simple and accurate methodologies as to render the likelihood of erroneous results negligible 2 pose no reasonable risk of harm if performed incorrectly or 3 are cleared by FDA for home use Tests of Moderate Complexity and Tests of High Complexity are differentiated by the following criteria 1 knowledge needed to perform the test 2 training and experience required 3 complexity of reagent and materials preparation 4 characteristics of opera tional steps 5 availability of calibration QC and proficiency testing materials 6 trouble shooting and maintenance required and 7 degree of interpretation and judgment The majority of devices that have been categorized fall into the Moderately Complex category The AVOXimeter has been categorized as Moderately Complex A copy of the letter received from the CDRH has been included page 1
17. en Blacken the square that corresponds to these values on the appropriate OC Log sheet If all four values obtained from the two filters are within the acceptable ranges then you have confirmed that the device is calibrated and ready to report valid clinical data If any one of the four values it outside its range then remedial action must be taken THb 2 7 7 8 3 93 5 0 96 5 Orange QC Filter 16 4 to 17 6 g dL for 1000E 37 2 to 40 8 for 1000 38 0 to 40 0 In addition to confirming that the AVOXimeter is calibrated the filters assess the status of the optical system If blood has contaminated the optics the readings from the OC filters will not fall in the acceptable range Most of the time contamination of the optics is respon sible for these out of range readings Consult the Operator s Service manual for instruc tions on how to disassemble the unit and clean the optics or call A VOX Systems at 800 225 2869 for assistance NOTE Contamination of the optics usually happens because of over filling of the cu vettes Review the instructions for proper cuvette filling technique in the Operator s Service manual Aqueous CO Oximeter Controls Aqueous control solutions are available from many sources A VOX Systems Inc recom mendis controls from only two sources Instrumentation Laboratory IL manufactures and sells Multi 4 CO Oximeter controls in several levels These controls
18. eous control will be accompanied by an insert sheet This insert sheet will have a series of acceptable ranges for a variety of instruments Where provided use the values range for the AVOXimeter 1000 If the insert sheet for the IL Multi 4 controls does not report ranges for the AVOXimeter use the ranges specified for the Radiometer OSMG If the values for O Hb and THb fall within the acceptable range then the verification of calibration was successful If either of the two values falls outside the acceptable range then the unit may need recalibration Call A VOX Systems Inc at 800 225 2869 for assis tance in recalibrating DOCUMENTATION Many times institutions fail inspection not because they did not perform the required QC procedures but because they neglected to document them We have tried to make the OC process an easy one to perform and document QC Log sheets for each type and level of control material have been provided in this kit Feel free to make as many copies of these Log sheets as you need RNA CO Oximeter Controls can only be used on the AVOXimeter 1000E not on the AVOXimeter 1000 11 AVOXimeter Compliance Guide Rev3 98 V PROCEDURES MANUAL Specimen requirements collection preservation etc If samples cannot be analyzed immediately they should be kept in tightly capped syringes and refrigerated until they can be analyzed Samples should not be analyzed if they are more than 24 hours old Equipment
19. ey are unable to compensate for the presence of carboxyhemoglobin or methemoglobin Pulse oximeters report O Sat as SpO AVOXimeter Compliance Guide Rev3 98 A patient who is a chronic cigarette smoker could have 5 7 of his THb bound with carbon monoxide A pulse oximeter could easily report a SpO of 99 for this patient If the patient s was 5 a SpO of 99 would be an unreasonable result A patient who is on nitric oxide therapy or has taken certain medications nitroglycerin nitroprussides etc may have an elevated level of methemglobin Y MetHb Just like the cigarette smoker the pulse oximeter cannot detect this and may report an unreasonably high SpO B Whole blood oximeters Whole blood oximeters are designed to measure the oxygenated hemoglobin directly in sampled blood by optical or spectrophotometric methods However not all devices in this category report a true fractional O Sat Some devices limited by the number of wave lengths colors of light they use are not able to detect the dyshemoglobins or other inter fering compounds like fetal hemoglobin The AVOXimeter 1000 does report a true frac tional O Saturation Although the values for carboxy and met hemoglobin are not re ported they are internally measured and used in the calculation of O Saturation Suffi cient wavelengths are used to assure no interference from fetal hemoglobin or bilirubin In addition a novel optical system allows the
20. is correct Keep in mind more expensive does not mean more accurate If you find a bias or offset in your results call A VOX Systems We can adjust the calibration of your device to more closely match your reference standard 2 Precision In the above situation each Level was analyzed four times If you calculate the standard deviation for each Level you will have the precision data 3 Analytical Sensitivity amp Specificity There is no interference from bilirubin hemolysis carboxyhemoglobin methemoglobin or fetal hemoglobin 4 Reportable Range The specifications state that the AVOXimeter measures the range of O Hb from 0 to 100 The THb range is from 4 to 25 g dL 5 AVOXimeter Compliance Guide Rev3 98 5 Reference Range There is no reference range for O2Hb The result is dependent on the anatomical site from which the sample was taken For example arterial blood is typically 97 saturated with oxygen whereas venous blood contains less oxyhemoglobin According to the World Health Organization adults will have a reference range for THb of 12 0 to 16 0 g dL for females and 13 0 to 17 0 g dL for males D Procedures Manual A written procedures manual for the performance of all analytical methods used by the laboratory must be readily available and followed by laboratory personnel CFR 493 1211 A Procedures Manual can be found starting on page 12 E Perform and Document Calibration Procedures CLIA 88 requires the la
21. it values shown on the data sheet included with the controls e g the lower and upper THb values for the level 2 control might be 4 AVOXimeter Compliance Guide Rev3 98 12 8 and 15 0 g dL respectively therefore mean 13 9 g dL Use the values for all three levels of control 2 On the y coordinate use the values obtained from the AVOXimeter corresponding to the selected analyte THb and level of control 3 Compute correlation coefficient r slope m intercept b and standard error of the estimate Sy x Here is a hypothetical example Analyte O2Hb x mean from insert sheet y actual AVOXimeter reading Level 1 39 2 40 1 Level 1 39 2 39 8 Level 1 39 2 40 5 Level 1 39 2 39 9 Level 3 75 9 75 6 Level 3 75 9 76 2 Level 3 75 9 75 7 Level 3 75 9 76 6 Level 2 94 5 95 5 Level 2 94 5 95 2 Level 2 94 5 94 4 Level 2 94 5 95 4 For these artificial data slope 0 9933 intercept 1 013 standard error of the estimate 0 5196 correlation coefficient 0 9998 The specifications for the AVOXimeter 1000 state an accuracy of 1 0 therefore 0 51 is within the stated value NOTE This analysis should also be performed on the THb data Whenever a linearity study is done by comparing the AVOXimeter to another reference standard a paradoxical situation is created If you are comparing results of the AVOXimeter to a Radiometer OSM3 IL 682 or Corning 270 CO Oximeter you must arbitarily decide which device
22. lt is a set of simultaneous equations with as many equations as there are unknown concentrations c Thus if the optical pathlength 1 and the extinction coefficients e are known the concen trations cx cy and cz can be computed from this set of equations E ion 1 e aq e ue a quatio E ion 2 OD e Sy yi quatio E ion OD es asy 1 quation 3 Conventional whole blood oximeters use only two wavelengths to measure the relative concentrations of two hemoglobin species oxy and deoxyhemoglobin By contrast the AVOXimeter uses multiple wavelengths to obtain accurate measurements of HbO even if bilirubin and four different hemoglobin species are present in the sample Thus for the AVOXimeter the value reported on the display for HbO is defined as 7oHbO HbO Hb HbO HbCO HbMet Equation 4 Similarly the AVOXimeter reports a value for the total hemoglobin concentration that is the sum of the concentrations of oxy deoxy met and carboxyhemoglobin THb HbO Hb MetHb Equation 5 To overcome the light scattering that red blood cells cause the AVOXimeter makes an assessment of the amount of light scattering in each sample employs proprietary optics and mathematical algorithms patent pending to correct its measurements for light scatter ing and thus obtains an accurate measurement of both oxyhemoglobin saturation an
23. m 6 Remove the cuvette as soon as the analysis is complete Do not leave the cuvette in the oximeter Although the results disappear from the display when the cuvette is withdrawn you do not need to write the results down after each analysis because the AVOXimeter stores the results of 100 analyses The AVOXimeter 1000 will store the data until the unit is turned off The AVOXimeter 1000E will store the data until it is purged by the operator 7 Sodium or lithium heparinate is the anticoagulant of choice Citrate is known to change the pH of the blood and cause errors in spectrophotometric measure ments Similarly fluoride oxalate should be avoided 8 Excessive volumes of anticoagulant lead to dilution errors 12 AVOXimeter Compliance Guide Rev3 98 Reagent and calibrator preparation Only syringes are required for routine analysis of blood samples The Instrumentation Laboratory IL Multi 4 Control solutions used to verify calibration must always be kept refrigerated Expiration dates for this material must be carefully observed Commercial sources are given in the Operator s Manual No preparation of the material is required it is simply injected into a cuvette as any blood sample would be Calibration procedure Each time you receive a new box of cuvettes you must inform the AVOXimeter of the pathlength of the cuvettes currently in use To do so press the Main Menu key and select Option 1 to reach the Calibration
24. s and Supplies In terms of effort this may be the most difficult requirement to attain compliance Each laboratory must test the methodology and equipment to assure test results are within the stated performance specifications CFR 493 1213 This means that prior to reporting pa tient results each laboratory must verify the performance for the following characteristics 1 accuracy 2 precision 3 analytical sensitivity and specificity 4 the reportable range of patient results 5 the reference range normal values and 6 any other applicable perfor mance characteristics 1 CLIA 88 does not specifically require a linearity study However a linearity study for both total hemoglobin concentration THb and percent oxyhemoglobin O2Hb from which accuracy data can be obtained may be performed on the AVOXimeter in the follow ing manner Obtain Multi 4 CO Oximeter Controls Levels 1 2 and 3 from Instru mentation Laboratory all three levels are available in a Multi Pack part no IL33162 50 phone no 800 955 9525 Make sure that the correct pathlength for cuvettes currently in use has been set on the AVOXimeter Fill multiple cuvettes with each level of control analyze them on the AVOXimeter and record the THb and O2Hb readings thus obtained Plot and statistically analyze the results obtained for each analyte tHb O2Hb in the following way 1 On the x coordinate use the average of the upper and lower lim
25. t report the fractions of carboxy and methemoglobin they are measured and used in the calculation of 7oHbO Oxygen Saturation derived from PO or Blood Gas Analyzers Some laboratories use an O Sat that is reported on their Blood Gas Analyzer Blood Gas Analyzers measure the partial pressures of oxygen pO and carbon dioxide pCO in blood They also measure the pH of the blood From an empirical equation the O Sat is estimated This equation makes several assumptions and does not take into account the effects of dyshemoglobins or fetal hemoglobin The National Committee for Clinical Labo ratory Standards NCCLS states that Clinically significant errors can result from incorpo ration of a calulated value for SO in further calculation such as shunt fraction or by assuming that the value obtained is equivalent to fractional oxyhemoglobin NCCLS Doc C25 T p 6 What is an Oximeter Simply stated an oximeter measures oxygen however there are different types of oximeters A Pulse Oximeters A pulse oximeter utilizes the reflectance measurement of infrared IR light off the surface of the skin This measurement is used primarily for trending or general oxygenation as sessment of a patient in a critical care environment Pulse oximeters have severe limita tions Pulse oximeters cannot detect the presence of interfering substances that also bind with hemoglobin Because of the limited number of wavelengths they utilize th
26. venue Teterboro New Jersey 07608 1070 201 393 5000 212 736 0640 February 18 1997 A P Shepherd Ph D President A VOX Systems Inc 15315 Grey Fox Terrace San Antonio Texas 78255 Dear Dr Shepherd Thank you for bringing to attention the issue of quality control requirement on your whole blood oximeters Some recent instrument designs have challenged the traditional liquid control paradigm The approach you have outlined in your letter of January 10 appears totally appropriate acceptable to CAP requirements and within the intent of the CLIA 88 regulations must add that control limits must be set for the filter readings and appropriate actions taken when readings exceed the defined limits or exceed the control rules You mention in the letter that the filters do specify ranges Regarding CLIA 88 493 1218 b 2 on page 7166 states For quantitative tests the laboratory must include two samples of different concentrations of either calibration materials control materials or a combination thereof If we interpret the two QC filters as samples of different concentrations then this requirement is met Finally proficiency testing for some oximeters is problematic with currently available proficiency testing samples An acceptable alternative is to split samples with another method system or to utilize the results of the CO Oximeter controls in a blind manner Sincerely Q ej ges Harvey W Kaufman M D
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