[1] poct Flashcards
what does POCT stand for?
point of care testing
what is the definition of POCT
- specimen analysis is performed outside of the clinical laboratory setting
- testing done at ___ where immediate results can be delivered, allowing assessment and management to be given swiftly
– bedside
– physician’s office
– or any alternative site
other names of POCT (10)
- Near patient testing
- Bedside testing
- Remote testing
- Satellite testing
- Physician’s office testing
- Extra-laboratory
- Decentralized
- Ancillary
- Alternate site testing (AST)
- Rapid diagnostics
is it considered POCT if sa ambulance?
yes
is it considered POCT if outside sa lab door?
yes
conventional testing procedure vs poct
conventional testing procedure:
- patient arrival
1. triage
2. collect sample
3. sample processing
4. perform test
5. compile test results
6. analyze test results
- patient admitted/discharged
POCT:
- patient arrival
1. sample collection
2. load sample
3. analyze results
- patiend admitted/discharged
half of the time is saved by poct
advantages of poct (9)
- Cheaper and quicker traditional diagnostic methods
- Can be used in resource limited settings.
- Reduced preanalytical and post analytic testing errors
- Small sample volume for a large test menu
- Easy to use and reduces the need for training.
- Rapid data availability
- Reduced patient’s length of stay and waiting times in the hospital.
- Convenience for clinicians
- Ability to test many types of samples
disadvantages of poct
- Concerns about inaccuracy, imprecision, and performance
- Bedside laboratory tests performed by poorly trained non-laboratorians
- Quality of testing is operator-dependent
- Difficulty in integrating information system (HIS) test or results with hospital laboratory information system (LIS); lack of connectivity
- Narrower measuring range for some analytes
(RE)ASSURED criteria by WHO
R = real time connectivity
E = ease of specimen collection
A = affordable
S = sensitive
S = specific
U = user-friendly/simple to perform
R = robust and rapid (results available in less than 30 minutes)
E = equipment-free
D = deliverable to those who need the test
specimen requirements and procedures
3 primary stages in the POCT process
pre-analytical, analytical, post-analytical
specimen requirements and procedures
pre-analytical
occurs before running the POCT on a sample; involves collection, transport, preparation, and loading
specimen requirements and procedures
analytical
actual testing sequence of a POCT is conducted
specimen requirements and procedures
post-analytical
begins when testing is complete, and an obtained result is available
treatment and management of patient diagnosis
important pre- and post-analytical errors in poct diagnostic testing
pre-analytical errors (7)
- Lack of preparation of the patient
- Lack of information about the patient’s condition
- Inappropriate sampling technique
- Wrong or missing additives to blood
- Mishandling and/or mislabeling of patient specimen
- Specimen contamination
- Degradation of specimen due to delays in specimen processing
important pre- and post-analytical errors in poct diagnostic testing
Post-analytical errors (4)
- Misreporting patient result
- Recording wrong patient test results
- Lost data
- Delayed reporting of critical results
important pre- and post-analytical errors in poct diagnostic testing
analytical errors in relation to POCT (1-2)
- there is a problem with the machine
– low battery
– inability to turn on
important pre- and post-analytical errors in poct diagnostic testing
Factors influencing these errors and problems include the ______ and the ______
Factors influencing these errors and problems include the setting (practice, hospital, etc.) and the extent to which the instrument is within a network (availability)
important pre- and post-analytical errors in poct diagnostic testing
what is irrelevant for poct
Transport, storage, and centrifugation are irrelevant for POCT. Evaluation of the test material is mostly unnecessary, as whole blood is used
important pre- and post-analytical errors in poct diagnostic testing
what is of greatest importance in the pre-analytical process?
Correct collection of the sample is of the greatest importance in the pre-analytical process
important pre- and post-analytical errors in poct diagnostic testing
POCT devices (6)
-
commercial benchtop devices
– centrifugal discs
– cartridge-based -
commercial handheld devices
– drug abuse detection
– disposable cartridges for saliva samples -
uPADs
– beta-hydroxybutyrate detection from whole blood samples -
smartphone-based devices
– disposable microchip
– semen sample
– optical attachment -
microfluidic multiplexed devices
– multianalyte antibiotic detection from plasma samples -
stand-alone POC devices
– nucleic acid amplification test from nose swab samples with colorimetric readout
technology
POCT is accomplished using ___
POCT is accomplished using portable instruments
easy to carry
technology
many point-of-care test systems are in the form of
many point-of-care test systems are in the form of easy-to-use membrane-based test strips, often enclosed by a plastic test cassete
para dli ma contaminated with air (unlike urinalysis strips)
POCT application
pregnancy testing
parameter (1) and sample (2)?
which sample is more confirmatory?
- parameter:
human chorionic gonadotropin (HCG) - sample:
urine, semen
semen is more confirmatory than urine
semen is more confirmatory than urine
POCT application
urine dipstick analyses
parameter (9) and sample (1)?
- parameter:
ascorbic acid, glucose, bilirubin, ketone, SG, blood pH, protein, urobilinogen, leukocytes, nitrite. - sample:
urine
POCT application
microalbumin screening
parameter (1) and sample (1)?
what is the clinical significance(?) of the parameter?
- parameter:
albumin - sample:
urine
- presence of albumin means is kidney is not filtering properly
- albumin is a fat protein and should NOT be in urine (usually reabsorbed)
POCT application
infectious agents detection
parameter (7) and sample (2)?
match the parameter to sample
group A strep, influenza A + B, HIV, chlamydia, trachomatis antigen, MRSA, helicobacter pylori-specific IgG antibody
- sample:
swab, serum
MRSA - staph aureus; helibacte - GIT bacte that can withstand GI acidity
swab:
* influenza a + b
* MRSA
serum:
* helicobacter pylori-specific IgG antibody
POCT application
fecal occult blood test (FOBT)
parameter (1) and sample (1)?
for what
- parameter:
hemoglobin - sample:
stool
occult means hidden
- hemoglobin is the breakdown of RBC
- to check for colon cancer / bleeding / polyps
POCT devices
single-use qualitative strip or cartridge and/or strip devices
how do u know qualitative? what differentiates it from quanti?
examples?
a wide range of devices, including single pad urine test (dipsticks) and test kits
quali - reference values (words); quanti - numbers (trace /25% + unit)
- dipsticks/urine strips
- test kits
POCT devices
dipsticks/urine strips
single-use qualitative strip or cartridge and/or strip devices
generally dried, porous matrices with impregnated carrier elements that interact with the analyte(s) when exposed; chemical reaction usually results in a color change
POCT devices
test kits
single-use qualitative strip or cartridge and/or strip devices
example?
utilizes a layer of suppporting materials, such as porous paper of cellulose fiber filters or woven meshes
example: home pregnancy test
POCT devices
parameters + reaction time?
dipsticks/urine strips
- ascorbic acid, glucose, bilirubin - 30secs
- ketones - 40secs
- specific gravity - 45secs
- pH, protein, blood, urobilinogen, nitrite, albumin - 60secs
- leukocyte esterase - 120secs
test kits
pregnancy test kits
(antibodies and antigen? specimen and principle?)
whats the 2nd line for?
considered ba first morning urine if first ihi nimo sa hapon?
- use antibodies to detect human chorionic gonadotropin (HCG), a hormone that can be deteeceted in the urine
- specimen: first morning urine (concentrated urine)
- principle: lateral flow technology (capillary motion)
control region - to know if daot ba ang test kit or expired
well, yes
test kits
how does a lateral flow test work?
what is a test line and control line?
analyte –> conjugate pad captures analytes –> membrane –> test line and control line catches antigens –> wick gets excess antigen
- test line - utilizes a combination of antibodies including a monoclonal hCG antibody to detect elevated levels of hCG
- control line - composed of goat polyclonal antibodies and colloidal gold particles
test kits
HBsAg Test Kit
explain its principle
- detects hepatitis B surface antigen in human serum or plasma
- sample: serum/plasma
- principle: sandwich immunoassay
placement of antigen is sandwiched between 2 antibodies
test kits
fecal occult blood test (FOBT)
what is the antigen?
- a lab test used to check stool samples for hidden (occult) blood
- occult blood may indicate colon cancer or polyps in the colon or rectum
- can only detect the presence pr absence of blood - it cannot determine what’s causing the bleeding
oh naur u have bleeding but idk what – needs confirmatory test
hemoglobin
poct devices
Single-use quantitative cartridge and strip test with monitoring devices
do we take the blood dayon after puncture?
do we still callibrate or perform QC? how?
- They include a meter or monitoring device thereby enabling for the detection and quantification of analytes
NO! wipe 1st drop of blood cus it may have skin fragments or alcohol
YES! naay strip para ana
poct devices
Coagulation monitoring
what is coagulation? what section ni usually?
common coagulation tests checked? (5)
Done to evaluate warfarin and heparin therapy using coagulation POCT analyzer
basically checks blood
when blood clots; hematology section
- Prothrombin time (PT)
- International normalized ratio (INR)
- Activated partial thromboplastin time (APTT or
PTT) - Activated clotting time (ACT)
- Platelet function
poct devices
coagulation poct devices (5)
which ones can be used bedside?
ngano diay if naay coagulation problems? asa ni commonly makita?
- Cascade POC – ACT, APTT, PT/INR
- CoaguChek XS Plus – PT/INR
- GEM Premier 4000 - ACT, APTT, PT/NR
- iSTAT- ACT, PT/INR
- Verify Now – platelet function
coaguchek and istat
- abnormal clot formation –> stroke/pulmonary embolism
- diabetic ppl (taas ug sugar) - tendency dli mo clot ug tarong ang blood
poct devices
bleeding time
erm what about bleeding time?
what are the different methods?
- A non-instrumented test ordered by the physician to evaluate capillaries for platelet plug formation
- Used for pre-surgical screening and detection of problems involving hemostasis
determines how long bleeding stops when masamad ka; bleeding time
- Duke method (finger and earlobe)
- Ivy method
- Copley-Lalitch Immersion Test
- Surgicutt method
bleeding time
duke method
um when should u start timer ???
what is abnormal bleeding time
start timer immediately after puncture
4min bleeding time –> prolonged –> low platelets –> capillaries of patient
bleeding time
ivy bleeding time
ref values??? and when do u start timer?
standard/naas manual: 40mmHg, 30secs clotting time
start time immediately after 1st puncture
idk what 8min and 35 secs means
bleeding time
copley lalitch immersion test
37 degrees C - same sa body temp, stop timer when bleeding stops
bleeding time
surgicutt method
- IV method
- 40 degrees
- no lancets
- most standardized
- keloid
- clotting: 2nd drop
- bleeding time: ASAP
poct devices
blood gas analyzer
what are its parameters?
what is the sample and anticoagulant? nganong e check nato ni?
- checks arterial blood gas
- ABG analysis has a prospective influence on patient care than any other laboratory determinants
- Tissue oxygenation, ventilation, and acid-base status are the most important factors in the management of critically ill patients
- Sample is arterial blood placed on ice and held at 0 °C until analysis
Parameters include pH, pO2, and pCO2
heparin (green stopper)
* respiratory alkanosis acidosis –> death
* CO2 out (hyperventilation) –> CO2 up, blood pH down (acidic, not good)
* arterial blood is bright red, veinous is dark red
* 90 degrees
* slows down cellular metabolism of cell so cells cant eat the O2
blood gas analyzer
what is pH?
pH refers to the concentration of hydrogen ions in a solution
blood gas analyzer
what is PCO2?
PCO2 is an indicator of how well air is exchanged between the blood and lungs; measure of the pressure exerted by dissolved CO2 in the blood plasma in proportion to the PO2 in the alveoli
blood gas analyzer
what is PO2?
PO2 is pressure exerted by dissolved O2 and the ability of the lungs to diffuse oxygen through the alveoli
blood gas analyzer
examples of blood gas analyzer?
- EPOC Critical Care Blood Gas Analyzer
- OPTI Critical Care Analyzer
still needs callibration
EPOC: cartridge –> ABG –> choose test u want to perform
OPTI: measures electrolytes, releases receipt
poct devices
i-STAT
i-STAT system range of tests? (7)
A cartridge-based analyzer with all the analytical requirements for the performance of a test contained within an individual cartridge
- lactate (CG4+)
- haematology (CH8+, EG7+)
- chemistries and electrolytes (CHEM8+, EG7+)
- cardiac markers (cTnl, CK-MB, BNP)
- endocrinology (B-hCG)
- blood gases (EG7+, CG8+)
- coagulation (PT/INR, ACT Kaolin, ACT Celite)
electrolytes
sodium
what do u call if too much/too little?
transmitting nerve impulses
- hypernatremia - too much Na
- hyponatremia - too little Na
electrolytes
potassium
what do u call if too much/too little?
helps in nerve conduction and muscle function;
regulates acid-base balance and osmotic pressure
- hyperkalemia - too much K
- hypokalemia - too little K
electrolytes
chloride
what do u call if too much/too little?
maintains the integrity of the cells by helping in
balancing osmotic pressure and acid-base and water
balance of the body
- hyperchloremia - too much Cl
- hypochloremia - too little Cl
electrolytes
bicarbonate ion
helps transport CO2 from the lungs resulting in the reduction of hydrogen ions and increase in blood pH
electrolytes
ionized calcium
helps in muscular function cardiac function, blood clotting, nerve transmission function of the body
- hypercalcemia - too much Ca
- hypocalcemia - too little Ca
poct devices
steps? (4)
- Insert two or three drops of blood into the cartridge.
- Close the cartridge and insert into the i-STAT handheld.
- View the results on the handheld screen within minutes.
- Upload information automatically into the LIS/HIS.
i-STAT System Integration with LIS/EMR
flow
i-STAT –> wireless transfer or i-STAT downloader –> POC data manager –> LIS –> EMR
non-invasive poct
Pulse oximetry
naur punctures
how does it work? ref values (hemoglobin)?
- For monitoring patient’s oxygen saturation
- Most common used sites for application are the fingernail and toenail beds
- Principle is based on the red and infrared light absorption characteristics of oxygenated and deoxygenated hemoglobin
measures oxygenated/deoxygenated
hemoglobin senses red light
deoxygenated - 660nm
oxygenated - 940nm
non-invasive poct
Transcutaneous measurement of bilirubin
nganong dli magamit sa dli babies?
whats up with bilirubin and babies? also what principle forda poct?
- The meter measures the yellowness of the subcutaneous tissue by measuring the difference in the optical density of two wavelengths through the skin
- Measurements are taken either on the baby’s forehead or sternum
conjugated na ang bilirubin sa non-babies = jaundice, pls get checked
- yellowness - bilirubin (e bulad ras init cus its light sensitive)
- measures unconjugated bilirubin
- the more bilirubin, the more light smth
- gestational age, body weight, skin color
poct principle(?): optical spectroscopy
non-invasive poct
Non-invasive hemoglobin monitors
why do we need to measure hemoglobin?
- A pulse co-oximeter that uses multi-wavelength sensor for spot check and continuous measurement
- The technology emits multiple wavelengths of light and then calculates the hemoglobin concentration based on the adsorption of light in the blood
hemoglobin carries O2
Hgb down = O2 down (not good)
non-invasive poct
GlucoWatch Biographer
- A device that extracts glucose through intact skin via reverse iontophoresis where it is detected by an amperometric biosensor
- Can provide glucose readings every 20 mins for 12
hours
veins n capillaries – measuring glucose ?
other tests performed through poct?
- cardiac troponin T and troponin I
- lipid testing
- B-type natriuretic peptide (BNP)
- C-reactive protein (CRP)
- glycosylated hemoglobin
- hematocrit
- hemoglobin
- lactate
- skin test
- strep testing
other tests performed through poct
Cardiac Troponin T and
Troponin I
whats this for?
Gauge the effectiveness of the thrombolytic therapy being administered to patients who have suffered from heart attacks
heart attack / myocardial infarction
other tests performed through poct
lipid testing
whats this for?
Measures the alanine transferase (ALT) of patients under lipid-lowering medication
measures ALT (enzyme in liver)
cholesterol up, ALT down
other tests performed through poct
B-Type Natriuretic Peptide (BNP)
Differentiates chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF)
other tests performed through poct
C-Reactive Protein (CRP)
what section and is this specific?
Detects and evaluates infection, tissue injury, and other inflammation disorders
- clin chem + immuno sero
- non-specific (screening); still needs diagnostic/confirmatory test
other tests performed through poct
Glycosylated hemoglobin
erm whats the difference between this and FBS?
Diagnostic tool for diabetes therapy monitoring
- HbAl-C
- this one takes 3 months while FBS takes like a day or smth
- more accurate than FBS
other tests performed through poct
Hematocrit
what about hematocrit?
Measures the volume of the red blood cells
O2 down, bone marrow: RBC up, hematocrit up
other tests performed through poct
Hemoglobin
whats this for?
Checks the hemoglobin level to manage patients suffering from anemia
anemia
other tests performed through poct
Lactate
measures what?
Evaluates the severity of lactic acid disorder and stress response of the patient
lactate acid levels
other tests performed through poct
Skin test
what about it
Checks contact with allergens and determines if the body has developed antibodies
derma diff
other tests performed through poct
Strep testing
whats this for and where is it collected?
Detects the presence of group A streptococci
- bacterial pharyngitis
- collect sa tonsils, or uvula if wlay tonsils (basta dont collect sa tongue)
