Health and safety equipment in the lab Flashcards
Give some examples of legislation that governs health and safety in the lab
- COSHH (2002) - covers diseases, especially zoonotic ones, stains and other chemicals used for analysis (eg formalin)
- Health and Safety at Work Act (1974)
- Hazardous Waste Regulations (2005)
- Environment Protection Act (1990)
What are some common hazards in the lab?
Spillages, sharps (needles/blades/glass), flammable substances
What can chemicals be labelled as?
- explosive
- flammable
- gases under pressure
- oxidising
- corrosive
- harmful/irritant
- toxic
- serious health hazard
- harmful to the environment
What are some examples of zoonotic diseases?
- salmonella (from faeces)
- rabies (from affected fluid)
- tetanus
- ringworm (very infectious)
- giardia (caused by parasite-protozoa)
- leptospirosis (from affected urine)
- e-coli (bacteria based)
- campylobacter (caused by a parasite)
- brucellosis (bacteria based - from affected urine, discharge and bodily fluids)
- MRSA (superbug, very resistant to antibiotics, nosocromial)
Define NOSOCROMIAL INFECTIONS
Health care associated or hospital acquired infections
What are some standard rules that should be followed in the lab?
- hair must be tied back
- a lab coat or apron must be worn
- appropriate PEE (gloves/mask/apron) must be worn, do not contaminate pens
- remove jewellery
- wash hands after every exam
What may be included in a lab SOP?
- entry restricted to authorised personnel only
- jewellery must be removed and long hair tied back
- no smoking, drinking or eating in the lab
- the lab must be kept organised and tidy
- cupboards should not be above eye level
- all staff should be aware of potential zoonotic risks
What are the key parts of the microscope?
The eyepiece, the body, the limb/arm, the mechanical stage, the coarse and fine focus knobs, the foot/base, the rheostat, the bulb, the substage condenser, the iris diaphragm, the Vernier scale, the objective lenses, the nosepiece.
Describe the microscope eyepiece
The part of the microscope that the operator uses to view the sample. Contains two lenses, the ocular (closest to the eye) and the field (closest to the scope).
Generally x 10 magnification
Describe the body of the microscope
The main part of the scope; sits beneath the eyepieces
Describe the limb/arm of the microscope
The part of the microscope that should be used to transport it - the scope should be picked up and put down when moving it, never dragged or pulled across a surface
What are the three different types of microscope head?
Monocular, binocular, trinocular
Describe the coarse and fine focus of the microscope
Coarse focus is larger one, fine focus is the smaller one. Both combined raise/lower the mechanical stage to allow the image to be focused
Describe the foot/base of the microscope
Should be supported when transported
Describe the rheostat of a microscope
Alters the level of light intensity produced by the light source
Describe the light source/bulb of the microscope
Has an illuminator condenser lens. Helps to control the light
Describe the substage condenser of a microscope
Sits underneath the stage and moves up and down, condenses light and makes the image sharper and brighter. The iris diaphragm sits on top of the substage condenser, and should be right under the sample
Describe the iris diaphragm on a microscope
Sits on top of the substage condenser. Adjusting this increases or decreases the amount of light passing through the condenser. Helps to ensure a clear sample.
Describe the objective lenses of a microscope
Normally 4 of them. Each of them have a specific purpose
x4 scanning lens
x10 low power lens
x40 high power lens
x100 oil immersion lens
What is the Vernier scale?
Horizontal and vertical vernier scales allows specific placement of specimens to be recorded and relocated
Describe the mechanical stage of a microscope
The flat platform where the slide sits. Has a hole in the middle to allow light to pass through and illuminate the specimen. The stage can be moved up and down with the focus control knobs, as well as horizontally and vertically.
Describe the nosepiece of the microscope
Rotates, and houses the objective lenses
How should microscopes be stored when not in use?
They should be switched off after use, kept in a dust proof box or covered with a plastic sheet. It should be stored away from moisture, heat, and water. It should be cleaned immediately after use and lenses cleaned correctly.
How would you work out the total magnification of a microscope?
It is a combination of the power of the eye piece and the objective lens e.g. if the eye piece is x10 and the objective lens chosen is x40, the total is x400 mag (10x40)
What is the purpose of the scanning lens?
Used to scan for areas of interest on the slide
What is the purpose of the low power lens?
Often used for urine samples and looking for crystals, for faecal egg counts, and for hair and skin samples
What is the purpose of the high power lens?
Used for RBC counts and WBC counts
What is the purpose of the oil immersion lens?
Must be focused on a specific site - the lens cannot move around and must stay in contact with the specimen/oil. Used for looking at FNA samples, differential WBC counts
What is the battlement technique?
A technique used for viewing samples in a methodical manner, ensuring that all the slide is viewed
How would a vernier scale reading be written?
As coordinates (x,x) (y,y)
Which of the two vernier scales move?
The small vernier scale will move with the sample, the larger one is fixed as part of the mechanical scale
What kind of surface should a microscope not be kept on?
A vibrating one (i.e. next to a centrifuge) as it can damage the microscope
What is the objective of centrification?
To separate the cells from liquid components in a substance. The cells are more dense, so settle at the bottom, and the supernatent stays on top
What are some uses of centrifuged samples?
- for blood samples (haematology/biochemistry)
- PCV readings in haematocrit tubes
- urine (analysis of casts, crystals and blood)
- faeces (used for FECs and identification of bacteria)
other common examples are synovial fluid and exudate
What are the three different designs of centrifuges?
- swing out
- angle head
- haematocrit/microhematocrit
All do the same thing just in different designs
Describe ‘swing out’ centrifuges
The sample will be almost vertical when starting. The rotor swings out when spinning, changing the sample to being horizontal due to centrifugal force. The sample should be equally balanced within the centrifuge
Describe ‘angle head’ centrifuges
Most common. The sample is held at a fixed position - 40 degree angle usually
Describe ‘haematocrit’ centrifuges
Specifically for PCV samples. There are special slots for the capillary tubes
Describe a ‘microhaematocrit’ centrifuge
A smaller type of haematocrit centrifuge, requiring smaller tubes and samples
What are some key safety points for use of centrifuges?
- always use on a flat, secure surface
- ensure the safety plate is on and secure before starting
- ensure the samples are fully sealed
- ensure the samples are balanced around the centrifuge
- ensure regular cleaning and servicing
At what speed and length of time should whole blood be spun for?
10,000 revs per minute for 5 minutes
This is the same for blood tubes and capillary tubes
At what speed and length of time should urine be spun for?
1500-2000 revs per minute for 5 minutes
At what speed and length of time should faeces be spun for?
1000-1500 revs per minute for 3 minutes
What different types of biochemistry analyser are there?
Wet - uses fluid and looks at chemical reactions. Uses plasma/serum and UV lights to detect chemical changes
Dry - uses slides that are impregnated with chemicals that interact with the sample
What are some examples of parameters that can be read by biochemistry analysers?
Renal parameters, protein levels, pancreatic enzymes, liver parameters, energy metabolism, electrolytes
What is a colorimeter in a biochemistry machine?
It looks at the absorbance of specific colours of light
What is a spectrophotometer in a biochemistry machine?
Measures the transmittance or reflectance of light as a function of wavelength
Describe the dilution function within a biochemistry analyser
Gives a more accurate result if the initial result is too high
What are some instances in which you would run biochemistry analysis for an animal?
- to identify diseases/problems
- to monitor the function of specific organs, particularly if the animal is on long term medication
- prior to anaesthetics
What are some examples of handheld analysers?
Glucometers, ketometers, EPOC
What are some key rules for care and maintenance of analysers?
- must be kept in a safe and secure position
- be kept at room temperature
- regular quality control testing
- regularly cleaned screens
- used in accordance with manufacturers
What are haematology machines used to assess?
Blood cell parameters - they complete differential cell counts
What stains are usually used in haematology machines?
Acridine orange, and fluorescent lamps
What is the main purpose of haematology machines?
Differential cell counts. Uses flow cytometry (lasers) to identify type of cells, their density and how many of them there are
What is involved in maintenance of haematology machines?
Regular changing of reagent bottles, , calibration to ensure accuracy and regular cleaning
What are the key electrolytes that are tested for?
Na+ (Sodium)
K+ (potassium)
Cl- (chloride)
What can hormone analysers test for?
Hormones including cortisol, T4 and progesterone. May be in house or through an external lab
Define QUALITY CONTROL
Measures that must be included during each assay run to ensure the test is working correctly, the results are valid and that they can be trusted. Should be done regularly. May be with an external sample sent specifically for calibration testing
What is the best way to assess cell morphology?
A blood smear
Define SPURIOUS
Not being what it purports to be; false, or fake results
What does total proteins measure?
The total amount of protein in the blood, measured as g/100ml or g/l
What does specific gravity measure?
The concentration of a patient’s urine.
Higher SG = more concentrated
Lower SG = less concentrated; more dilute
Define QUALITY ASSURANCE
The overall programme that ensures that the results given by the laboratory are correct.
Involves correct sample taking, storing and recording, as well as ensuring the test is run correctly, and the correct results are reported to the correct vet for the correct animal
What is a refractometer and what can it be used for?
A handheld analyser that can be used for urine specific gravity and total proteins
How often should external quality assurance testing be done?
At least quarterly
What external factors can skew urinalysis results?
- containers that free catch samples are brought in by clients
- blood contamination from cystocentesis
- poor user technique, not calibrating refractometer
What is the correct method for using a refractometer?
- Put on gloves
- Calibrate the refractometer using the correct scale and distilled water
- Remove the distilled water
- Drop a few drops of sample on the refractometer
- Read the result by holding the refractometer to the light and noting the colour change. Ensure the correct scale is used
- Wipe clean and report results
What are the correct parameters for urine specific gravity in dogs and cats?
Dogs - 1.015-1.045
Cats - 1.020 - 1.040
What does elevated total proteins generally indicate?
Dehydration, immune-mediated disease, lactation, infection, and neoplasia
What does decreased total proteins generally indicate?
Renal disease, haemorrhage, malnutrition, malabsorption, hepatic insufficiency, or pancreatic insufficiency
What does the Hazardous Waste Regulations (2005) require?
Requires any organisation that produces any for of hazardous waste to register with the environment agency. Hazardous waste generally includes anything that has been in contact with an animal, including cytotoxic waste.
What is the normal range for total proteins in dogs and cats?
60-75g/l
