1010 unit 3 Flashcards
what is a control?
represents a specimen with a known value that is similar in compositions to the patients sample
describe random errors
errors that affect the reproductivity of a test system. associated with 1-32, R-4s, and outliers
what is sensitivity?
defined as the proportion of cases with a specific disease that gives a positive test result. those results are truly positive
what is an analyte
substance or constituent being measured
how do you develop a reference range?
1) at least 30 healthy people are tested
2) test results are averaged to create a mean
3) calculate SD
4) calculate both the +/- 2SD
5) calculate the range using -/+ 2SD from the mean
what is osmolarity formula?
osmoles of solute per liter of solution
what is quality assurance/assessment
comprehensive set of policies, procedures, and practices that ensure the laboratories results are accurate and reliable. Includes record keeping. calibration and maintenance of equipment. QC, proficiency testing and training
what is specificity?
defined as the proportion of cases with the absence of the specific disease that gives a negative test result. Those tests are truly negative
what is the warning rule where 1 control value outside +/- 2SD?
1-2s
what is proficiency testing?
program where samples are sent to a group of labs to analysis. The results are then compared with the other labs. A mean by which quality control between laboratories is maintained
what are reference values?
“normal values”, the laboratory must provide reference values for the physician so that they know what is considered normal for that assay
what is standard deviation?
statistical term for the mathematical expression of a guassian curve. Measures the scatter of dat around the mean of a guassian distribution
what is mean?
average of set of numbers
what are standards?
highly purified substances of a known composition. used to calibrate and measure accuracy
what is median?
middle value of body of data
10x
rejection rule, 10 consecutive points are all above or below the mean
what is the rejection rule for 2 consecutive control values outside of -/+ 2SD
2-2s
what is the rejection rule for 1 control value outside of -/+ 1 SD?
1-3s
what is mode?
value that occurs most commonly in the mass of data
what are systemic errors?
–errors that affect the accuracy or closeness to true value. Causes bias in a single direction only.
–associated with 1-3s, 2-2s, 41-s, 10x, shifts, trends or calibration failure
what is CV%?
(SD/mean) x 100 = CV%
–helpful is comparing precision differences among assays and methods
what is calibration?
comparison of the measurements of an instrument or glassware to a known physical constant
what is a trend?
four consecutive control values moving in one direction
what is a shift?
four consecutive control values all above or below the mean
what are some sources of systemic errors
–worn pump tubing
–decreased bulb output
–improperly calibrated pipettor
how often is a control value expected to fall outside of 2SD?
1 in 20 runs
what are characteristics of controls in the lab?
1) similar to composition to unknow specimen
2) has known concentration
3) is included in every batch or run
4)must be treated in the exact same way as the patient specimen
5) reuslts must fall within the set of QC results to report patient results
what is “out of control”
a problem observed determining that patients results cannot be reported
what are some sources of random errors?
–worn pump tubing
–varying bulb output
–technique
-unstable reagent,
–unstable environment
68% of all values in a measured group fall within this area
1SD
what is the rejection rule that is 1 control value exceeds the mean +2SD and 1 control value exceeds -2SD?
R-4s
99.7% of all the values in a measure group fall within this area
3SD
95% of all values in a measured group fall within this area
2SD
what to do for troubleshooting Out of Control QC
follow the manufacturer’s troubleshooting procedure specified for the test procedure - may include ——-
–evaluation of type of expiration dates and calibration dates
–evaluation of type or error; systemic or random
–evaluating recent events
–preparing a new control material
quality management consist of what?
–quality assurance
–quality control
In addition to blood and urine, what are the major types of body fluid specimens that can be tested by clinical laboratory?
–synovial fluid
–cerebrospinal fluid
– peritoneal fluids
–pericardial fluid
–sweat
–seminal fluid
The CLIA ‘88 amendment regulations established minimum requirements with general QC systems for what?
all nonwaived testing
the abbreviation TJC stands for an organization that does what ?
accredits hospitals and inspects clinical laboratories
the abbreviation CAP stands for an organization that does what?
accredits only hospital laboratories only
the abbreviation for COLA stands for an organization that does what?
accredits physicians offices
the abbreviation for CLIA stands for an organization that does what?
determines minimum QC requirements for nonwaived assays
ISO 15189 is intended for what use?
medical laboratories
six sigma management focuses on what?
reduction of variability in laboratory results
what does CLIA ‘88 require?
participation in proficiency testing
if the incorrect anticoagulant is in a blood collection tube, it is a what?
an active error
incorrect identification of a patient is what kind of error?
preanalytical error
malfunction of a microprocessor that affects accuracy in testing is what kind of error?
analytical error
Transportation of a numeric critical value in transmitting a report is an what kind of error?
postanalytical error
blood from the wrong patient is an example of what?
preanalytical error
specimen collected in the wrong tube is an example of what?
preanalytical error
quality control outside of the acceptable limits in an example of what?
analytical error
proficiency testing is required by CLIA for what?
–nonwaived tests
–FDA cleared and approved moderate-complexity or high-complexity assays
if proficiency testing is not available for a specific analyte, what one alternate assessment needs to be conducted?
internal split-sample analysis
the delta check cutoff value may be presented as what?
–absolute change
–percent change
–rate of change
quality control evaluates the _________ phase of testing
analytical
what is the most encountered laboratory testing error?
systemic error
what is the “matrix” of a specimen?
–has components of a specimen other than the analyte of interest
–more closely resembles the patient specimen
precision is defined as what?
how close results are to one another
what is the coefficient of variation?
equal to SD divided by mean
what does total analytical error depend on?
-methods precision
-method accuracy
what does Levy- Jennings plots show?
values on a chart
when a specimen is transported to the laboratory, what is the optimum time for collection?
within 2 hours of collection
what is biometrics?
the science of statistics applied to biological observations
what is a major advantage of POCT?
–faster turnaround time
–lower cost
POCTs assays are usually in which CLIA category?
waived
over the counter kits are usually in which CLIA catergory?
waived
hemoglobin determination is an early example of what?
decentralized health care
an early commercial example of direct consumer genetic testing is:
cholesterol assay
what is the concentration at which most sensitive current laboratory assays can give a positive serum hCG result?
100 mIU/mL
the most specific assays for human chorionic gonadotropin (hCG) use antibody reagents against which subunit of hCG?
Beta
what is an important characteristic to be considered when selecting?
rapid turnaround time
what is the tricorder is modeled after?
original cell counters
what is the ultimate goal of the laboratory?
quickly produced results
what can computer technology be used for?
inventory control
what is the function of CPU?
exchange of information
what is the function of an interface?
short term memory
the laboratory can have directly connected computers that can access the hospital record system by what?
forming an LAN
what is an example of laboratory information system functionality?
quality control
what are some future challenges for laboratory automation standards?
developing uniform collection devices
what is the major benefit of laboratory automation?
faster turnaround time
what are steps in automation designed to mimic manual techniques?
pipetting of reagents
Define quality
Worth if services
What are 5 non analytical factors if quality assessment?
1) established laboratory policies
2) qualified personnel
3) appropriate methodology
4) laboratory procedure manual
5) proper procedure for specimen collection and storage
What are 2 analytical factors in quality assessment?
1) application of statistical analysis of results in quality assessment protocols
2) instrumental applications of statistics to measurements
What does Quality Assurance ensure?
Reliability of results
Functions of quantitative quality control program
1) provides guide to function equipment, reagents, and individual technique
2) confirms accuracy of testing when compared with reference values
3) detects increase in frequency (dispersion)
4) detects progressive drift values to one side of mean for Atleast 4 days (trend)
5) demonstrates abrupt shift/change from mean for 4 dAys in a row (shift)
What is process improvement?
QA and TQI are driven by pressure to contain the cost of good service
10 step monitoring process
1) assign responsibility for QA
2)define the scope of patient care
3) identify important aspects of care
4) construct indicators
5) define threshold for evaluation
6) collect and organize data
7) evaluate data
8) develop corrective action plan
9) assess actions; document improvement
10) communicate relevant information
What are the assessment requirement s?
1) request form must be completed by the physician directing patient care
2) time of receipt of specimen
3) request form must be clean and legible
4) information on accompanying specimen container must match request form
5) lab can accept only properly labeled specimens, if not the specimen is rejected
6) all containers must be labeled by the person doing the collection
7)specimens must be transported to lab in safe, timely, efficient manner.
8) specimens must be checked for acceptability
What are some components of a CAP QA program
1) procedure manuals
2) comparison on test results
3) proficiency testing
4) communications
What are major difficulties in guaranteeing reliable results invoiced in sampling procedure?
—Time of day —> circadian rhythms
— patients position —> lying or standing
— patients physical ability —> bed, ambulatory, or physically active
— interval of eating —> fasting
—time interval from blood collection to processing in lab
—storage containers
What are some procedural factors that can cause variance?
—aging of Chemicals/reagents
— personal bias of techs
__ laboratory bias due to —> environment, methods, apparatus
—changes in instruments
— changes in personnel
What is needed to determine sensitivity and specificity?
1) tests positive
2) tests negative
3) disease present (positive)
4) disease absent (negative)
What is true positive and true negative?
True positive —> subjects who have a positive result and also have the disease in question
True negative —> subjects who have a negative result and do not have disease in question.
What is false positive and false negative?
False positive —> subject who test positive but does not have disease in question.
False negative —> subject who test negative but do have disease in question
Those tests that are negative are try negative describes what?
Specificity
Results that are positive are truly positive describe?
Sensitivity
Normals are based on what?
Patient population
How to ensure clinically correct results ?
1) standards
2) control samples
3) proficiency testing programs
What are some characteristics of control specimen?
1) similar in composition to unknown specimen
2) has known concentration
3) is included in every batch or run
4) treated same way as patient specimen
5) results must fall within the set QC rules to report patient results
What is objective of controlling reliability of the laboratory results?
Reject results when there is evidence that more than the permitted amount of error has occurred
What should be on a control bottle?
— date of reconstitution
—date of expiration
— tech initials
What are characteristics of a control
— must be run at room temperature
— must be kept closed and refrigerated between runs
— data collection—> must mimic all conditions found when actually running controls during year
—must be run over a period of time
— must be Atleast 30 but the larger the better
What are the 3 control values?
—abnormal high
—normal
—abnormal low
A value may fall above the mean how often?
2.5% —> 1 out of 40
A value may fall below mean how often?
2.5% —> 1 out of 40 runs
What determines precision of CV?
The closer CV is to 1, the better the precision
What are CVS used for?
—comparison of methods
— comparison of labs
Define aliquot
A portion of a total amount of a solution or suspension
Define percent
—One part in every hundred
OR
—g or mL of solute per 100 mL of solution
What is PV
Photovoltaic cell—> an energy harvesting technology that converts solar energy into useful electricity
What is PPV?
Positive predictive value —> likelihood that an individual with a positive test result truly has the particular gene and/or disease in question
What is POCT?
Point of care testing—> testing that is performed near it at the site of a patient with the result leading to possible change in the care of the patient
What is waived testing?
Those tests that are determined by CDC or FDA to be so Simple that there is little risk of error
Define moderately complex tests
One requiring basic lab knowledgeable and training for personnel performing the test
What are high complexity tests?
Those that require clinical laboratory expertise beyond normal automation to perform
What are exponents used for?
To indicate that a number must be multiplied by itself
What are positive exponents
Indicates the number of times the base is to be multiplied by itself
What are negative exponents?
—Indicates the number of times the reciprocal of the base is to be multiplied by itself
—negative exponents represent a fraction
Define density
The amount of matter per unit volume of substance
Define specific gravity?
The weight of 1 mL of a solution compared to weight of 1 mL if pure water at 4 C
Define proportions
Are a way of saying that two ratios are equal
Define concentration of the solution
Amount of one substance relative to the amount of the other substances in the solution and is expressed in several ways (weight, volume per unit volume, or percent)
What can never happen to dilution?
Increase it
What is a mole?
The molecular weight of a compound in grams
How to perform a single dilution?
1 unit of the original specimen diluted to a final volume of 2, 5, or 10 units
Serial dilution procedure
1) tube 1 contains 1 mL of undiluted serum —> 1:1 dilution
2) tube 2 contains 1 ml of undiluted serum + 1 mL diluent —> 1:2dilution ( 1/2 x 1 = 0.5 ml of serum)
3) tube 3 contains 1 ml of 1:2 diluted serum + 1 ml of diluent —> 1:4 dilution ( 1/4 x 1 = 0.25 ml of serum)
4) tube 4 contains 1 ml of 1:4 diluted serum + 1 ml of diluent —> 1:8 dilution (1/8 x 1 = 0.125 ml of serum)
5) tube 5 contains 1 ml of 1:8 serum + 1 ml of diluent —> 1:16 (1/16 x 1 = 0.06 ml of serum)
what are two types of error analysis? what are they?
1) active error –> obvious. occurs at interference of healthcare worker and the patient
2) latent errors –> relative to the organization or design of a laboratory
what do standards test best?
accuracy and used to establish reference points to construct graphs
describe how accuracy and precision relate
accuracy IS precision with calibration
