Diseases of the Blood Flashcards
3 functions of the blood
- transport nutrients
- removal of waste
- transport of host defences
what are 2 things blood needs to be able to do?
- able to carry nutrients/waste/defences
- able to self repair
why does blood vessels need to be able to self-repair?
if vessel gets a hole in it needs to be able to repair itself so has no long lasting effect on platelets and coagulation
5 blood constitiuents
- cell component
- plasma protein (albumin, globulin)
- lipids
- nutrients
- water
can replicate each individually in a lab, but getting correct balance is hard
FBC
full blood count
RCC
red blood count
WCC
white cell count
PLT
platelet count
HCT
Haematocrit
- ratio of the volume of red blood cells to the total volume of blood.
- proportion that is cellular compared to liquid plasma
- 4/0.45
- low loosing too much or not making enough for requirements;
- high too viscous blood
MCV
mean cell volume
anaemia
low Hb
- Grams of Hb in litre of blood
- Lots of RBC with low Hb and be anaemic but can equally have few of RBC with lots of Hb and not be
leukopenia
low WCC
thrombocytopenia
low platelets
Thrombocytes are responsible for platelets - clotting
pancytopenia
all blood cells reduced
Bone marrow not working properly - all low
- One cell type - specific deficiency of something (reactive change)
if there is one blood cell deficiency it is a….
reactive change
if there is multiple blood cell deficiencies it is due to….
bone marrow failure
polycythaemi
raised Hb above the reference range
opposite to anaemia
Leucocytosis
raised WCC
can occur in infection and leukaemia
Thrombocythemia
raised platelet number
if there is one blood cell type increase…
reactive or pre-neoplastic
e.g. WBC higher in infection; raised Hb in higher altitude for lower O2 levels
if there is multiple blood cell types increases then….
pre-neoplastic (myelodysplasia)
- more than one raised cell line to get leukaemia
leukaemia
neoplastic proliferation of white cells, usually disseminated
- high WCC
- no lumps usually - uncommon to have lumps of white cells in circulation
lymphoma
neoplastic proliferation of white cells, usually a solid tumour
- in circulation and then enters organ e.g. spleen, lymph nodes
when would a blood transfusion be used?
when one or more components of the blood has to be replaced quickly (blood loss)
- red cells, platelets
- clotting factors (fresh frozen plasma)
or when the bone marrow cannot produce cells (production problems)
but generally avoid
why is it dangerous to have a sudden loss in RBC?
lowered O2 carrying capacity
what can occur if have low platelet count?
excess bleeding
- may transfuse before extraction
why should blood transfusions be avoided generally?
can only test for what we know
- many unknown antigens and diseases of blood that could cause a bad reaction/spread when transfused
blood transfusion process
sample taken from patient
Tested against known blood types
- Basic ABO compatibility
- Rhesus compatibility
- Does not always detect irregular antibodies (Too rare/unknown so cannot be tested for)
Tested against donated sample
- Take blood from transfusion packet and test
against patient
- See if any reaction occurs
Matched blood given to patient
group A blood has…
A antigens
B antibodies
group B blood has…
B antigens
A antibodies
group AB blood has…
A and B antigens
no antibodies
group O blood has…
no antigens
A and B antibodies
what is cross matching?
- Take blood sample
- Antibodies in blood
- Compare against patient sample
what blood type can be given to anyone?
O
- no known (A/B) antigens present so cannot stick to any antibodies
- no coagulation will occur
what blood type can receive any blood?
AB
- no known (A/B) antibodies present so cannot stick to any antigens transfused to them
- no coagualtion
3 transfusion complications
- incompatible blood
- fluid overload
- transmission of infection
what will happen if a patient is transfused incompatible blood?
RBC lysis (burst) - fever, jaundice, death
what will happen if a patient has a blood fluid overload after transfusion?
heart failure
- If healthy physiology and enough blood volume - when give them extra blood also gives extra fluid
- If they have heart pump issue - can exacerbate due to extra fluid so lead to heart failure more in elderly
what infections can be transferred in a blood transfusion?
Blood borne viruses
- CMV, Hepatitis B, Hepatitis C, HIV, TT virus
Prion Disease
- vCJD
Bacterial Infections
- Syphilis
is the coagulation cascade off when there is no local damage?
no - low level of coagulation turnover all the time
when damaged, get local chemical alterations which makes the process happen more rapidly in the area of need
how long can you be ok if stop making clotting factor?
1-2 days as there is a level present in the tissue due to the constant low level coagulation system
what does the coagulation cascade rate depend on?
forward enzymes against inhibitors (protein C and S)
fibrinolysis
break down of clot
3 components of haemostatic disorders
- vascular component
- cellular component
- coagulation component
what is the vascular component of haemostatic disorders?
retraction of the vessel (collagen disorder)
- hole smaller
- Inherited disorders of collagen - abnormal collagen, doesn’t behave how they should
what is the cellular component of haemostatic disorders?
Platelets number and function
- Plug hole
- Dynamic quick changes
- Can form antibodies to platelets take out of circulation for a while
what is the coagulation component of haemostatic disorders?
- adequate clotting (fibrin on top to stabilise it)
- adequate clot lysis
how can we assess platelet number?
FBC
how can we asses platelet function?
‘bleeding time’
unpleasant test
what drugs effect platelet function?
Aspirin and NSAIDs
- permanent effect on platelets
- 7-10 days to form new platelets
- Platelet adhesion altered for life span of cell
if platelet count is correct then how will they be expected to function?
normally
if there is a preneoplastic platelet count how will they be expected to function?
huge excess of platelets
often not normal function
if there is too few platelets how will they be expected to function?
work normally but not enough
what are the 3 factors for the coagulation component of haemostatic disorders?
- adequate amount of clotting factors
- adequate range of clotting factors
- proper balance between thrombotic and thrombolytic/fibrinolytic systems
what determines if there is an adequate amount of clotting factors coagulation?
synthesis and consumption
- Balance of make and use
- Drug can interfere with clotting factor synthesis
- Whole dynamic system run faster after trauma may run out quicker than anticipated
what determines if there is an adequate range of clotting factors for coagulation?
hereditary deficiency - VIII, IX 9but also 5 and 110
Replace the one CF and should return to normal
- Not all or nothing - spectrum of disease depend on proportion that you make, reserve in body
- e.g. haemophilia more men than women as X chromosome linked clotting factor as one wrong than 50% still made whereas men with abnormal X and Y so can may only have a small level of normal
Level of function of chromosome reflects level made
- Can get mid to severe haemophillicas dependnent on how much is expressed
when can you get increased tendencies to form blood clots?
under active systems e.g. on a plane, inactive
- leg or arm thrombosis
what controls blood clot formation and brekdown mainly?
blood vessel walls (endothelium)
cascading factors in blood
local chemical mediators make system faster in area
- tissue factors
what are visual signs of poor coagulation history? (3)
- purpura
- ecchymosis
- petechiae
what investigations can be down if a patient has a haemstatic disorder? (history of bleeding)
FBC (platelet numbers) sensible
Bleeding time (platelet function) tend not to be done, but can assess function
INR & APPT
LFT (Clotting factor synthesis)
- Ability of body to make prothrombin (how well can produce a clot)
- Test how well system works and how well can make clotting factors (liver function is inflammatory enzymes but no use for blood - need to see if liver has made clotting factors)
what is haemophilia?
inherited deficiency of factor VIII or IX
types A and B
what sex is affected more by haemophilia?
males
X chromosome associated condition
what is Thrombophilia?
excessive tendency to clot
- usually DVT (life threatening due to pulmonary embolism - clot block heart, wedge valve, no longer pump)
opposite to haemophilia
what can exacerbate Thrombophilia?
- Smoking
- Immobility – travel
- Surgery
- Pregnancy
- Medicines – oestrogen contraceptive pill
but genetically preconditioned
what can be used to reduces risk of unnecessary clot and thrombophilia?
anticoagulant medicines
what is therapeutic coagulopathy?
Where the coagulation system is manipulated by medicine to make clotting less likely.
either
- Reduce platelet adhesion and function (Usually prevent arterial thrombosis)
or
- Reduce activity in the coagulation cascade (Usually prevent venous thrombosis)
when would therapeutic coagulopathy be used?
Normal human and make blood clot less
- E.g. artificial heart valve don’t want to clot on this to cause it blocking
Give anticoagulants in people more prone to have clots
standard antiplatelet drug examples
- aspirin
- dipyrimadole
- clopidogrel
new antiplatelet drug examples
- prasugrel
- ticagrelor
standard anticoagulant drug example
warfarin
new anticoagulant drug example
- apixiban
- dabigatran
- rivaroxaban
what are dental aspects of haemostatic disorders?
ALWAYS LOOK for bleeding problems!
- skin - red spots or purpura
- mucosa - purpura or blood blisters
If in doubt TEST first
- FBC (Platelets), INR, APTT (activated partial thromboplastin time)
If known haemostatic problem ASK ADVICE from a dental specialist
- Before any treatment
Follow available SDCEP Guidance for dental care delivery
REMEMBER Local haemostatic measures
- make clotting more likely and excessive bleeding less
porphyria
abnormality of haem metabolism
very serious
most people unaware they have it until have an acute episode
2 main groups of porphyria
hepatic porphyrias
erythropoietic porphyrias
clinical effects of acute porphyria episodes
Photosensitive rash (at any time)
Neuropsychiatric disturbance in acute attacks (strange, unpredictable behaviour)
- Motor & sensory changes, seizures
- Autonomic disturbances
Hypertension & tachycardia
May be fatal
what can trigger acute porphyria episodes?
poorly understood
- many drugs - Including local aesthetic and commonly prescribed
- Pregnancy
- acute infections
- alcohol
- fasting
what are dental consideration in relation to porphyrias?
drug administration- Be VERY cautious about this
- Could be consequence when prescribe anything or give LA - can trigger unknown
- Read in BNF as soon as they say - as very severe
One possible cause of ‘local anaesthetic allergy’ reported by patients
