Topic 29 - Principles of blood pressure measurement. Flashcards
How many types of blood pressure are there? name them:
3
Systemic arterial pressure
Central venous pressure
Pulmonary pressure
For central venous pressure measurement, there are two main routes:
Direct
Indirect
Direct central venous pressure measurement
- needs catheterization
- accurate, enables fluid therapy, - invasive !!
Indirect central venous pressure measurement
= determination of venous congestion
Which veins do we examine in case of indirect central venous pressure measurement?
Peripheral veins
- v. jugularis
- v. saphena
- episcleral veins
4 .vena hepatica branches - v. cava caudalis
How can we perform indirect central venous pressure measurement?
Hepatojugular reflux test
Can also use US
In which cases can we use US indirect central venous pressure measurement?
- Increased central venous pressure, or other causes for venous congestion
- Lack of diameter change of caudal vena cava during respiration
- observation of congested/dilated v. hepatica branches in the liver
Definition of blood pressure measurement:
measuring the systemic arterial pressure
Is blood pressure the same as pulse pressure?
NO
Blood pressure can not be examined by palpation
What is the difference between pulse pressure and mean arterial pressure?
Pulse pressure= systolic pressure –diastolic pressure
Mean arterial pressure (MAP) = (diastolic pressure + pulse pressure) /3
What is the arterial pressure?
Cardiac output x complete peripheral resistance
What is cardiac output?
Heart rate x Ejection volume
What does the blood pressure depends on?
- Anatomical place
- Body position
- Heart rate
- Blood pressure itself
- SAP > DAP, MAP
SAP= Systolic Arterial Pressure
DAP = Diastolic Arterial Pressure
MAP = Mean Arterial Pressure
When do we perform blood pressure measurement in animals?
- To reveal secondary hypertension in case of known predisposing diseases
- To search for the cause of target organ damage
- To monitor the effect of blood pressure lowering drugs
- In case of severe diseases, shock
- To monitor anesthesia!!!
Why do we measure blood pressure, what can happen if we dont do it?
The animal can get hypotension or hypertension
= Low/high blood pressure
Causes for hypertension in dogs and cats:
- Can be stressed induced !!
- Measurement error !!
- Kidney disease
- Hyperthyroidism
- Adrenal gland disease
What can be the consequence of hypertension?
Target organ damage: Eye, brain, heart, kidney
Blood pressure measurement in small animals, two methods:
Direct/invasive method
Indirect/non-invasive method
How can we measure the blood pressure in small animals directly?
- Atrial cannulation - catheters
- Telemetry
How can we measure the blood pressure in small animals indirectly?
Doppler
Oscillometry
In general, what is the technique for measuring of blood pressure?
- Calm environment, examiner, (owner)
- Acclimatization (5-10 min)
- Mean of 3-5 measurements (maximum alterations less than 10% of SBP value)
- If high to be repeated (min. 30 minutes or another day)
- Cuff size is 30-40% of limb or tail circumference ?
How to measure the blood pressure with the Doppler-method?
- Forelimb behind the pawn, tail, (hind limb behind the pawn)
- aa. digitales palmares communes., a. caudalis mediana
- Only systolic value
- At any sized animal, mostly in cats (dogs less reliable)
- Needs training (technically more difficult than oscillometry)
How to perform the oscillometric method?
From the tail: A.Medialis Caudalis
If not possitble, then forelimb: A.brachialis
Easy, but produces more false measurements
Which blood pressure measurements is used in dogs?
Awake: HDO with tail cuff
Anaesthesia: Oscillometric
NO doppler (but better than nothing)
Which blood pressure measurements is used in cats?
Doppler and oscillometry
