Monitoring Cardiovascular System Flashcards
What can we monitor for the cardiovascular system?
Heart Rate/Rhythm - Stethoscope + palpation
Mucous membrane colour + CRT
Bleeding from surgical site
Blood Pressure
Haemoglobin oxygen saturation (SpO2)
What patient factors affect Heart rate/Rhythm?
Species
Breed
Age
Size
Stress levels
Drugs administered
Normal is roughly 60-120BPM
Why is it important to know a patients HR prior to induction?
To see if it deviates from normal rather than focusing on specific number
For comparison
Each patients resting HR is different
What are the problems with relying on Heart rate?
Presence of a heartbeat doesn’t tell you cardiac output
Could have inadequate circulation
Always use in conjunction with pulse palpation and blood pressure
What are the methods are assessing heart rate?
Oesophageal stethoscope - more accurate/reliable
Measure length before inserting
From incisors to scapula
Insert down side of ET tube - pull tongue forward
Can manipulate tube until clear sound
Normal stethoscope
Pulse palpation
Listen to heart whilst also palpating peripheral pulse
How does pulse palpation with auscultation help?
Listen to heart whilst also palpating peripheral pulse
Deficits identified by:
Palpation of a peripheral pulse that has an irregular rhythm/pauses
Pulse rate that is less than the heart rate determined with a stethoscope
What locations can you use for pulse palpation?
- Sublingual on the ventral aspect of the tongue
- Mandibular - not so common
- Digital metacarpal - very common
- Digital metatarsal - very common
- Dorsal pedal - usually palpable over the dorsum of the metatarsal area.
- Femoral medial aspect of the femur - easy to find
- Coccygeal artery on the ventral surface of the tail - not as common
Common mistakes of pulse palpation
Using your thumb
You have a pulse in your thumb so that can make it difficult to feel the patients’ pulse
Pressing down on the pulse too hard
Meaning you occlude it and therefore can’t feel anything
How can you assess CRT?
When an area of the gum is pressed, blood is forced out of the capillaries in this area
When you remove your finger there is a pale patch
Blood refills capillaries once finger is released showing return to original colour
Should be <2 seconds (~1.5-2 seconds)
What should healthy MM look like?
Pink and moist
CRT <2s
What do vasodilated mm look like?
Very pink
Dry/tacky
CRT paid
What causes vasodilated mm?
Sepsis
Anaesthetic drugs - anaphylaxis
Low MAP (mean arterial pressure)
What do vasoconstricted mm look like?
Pale
Wet CRT >2s
What causes vasoconstricted mm?
Anaemia
Inadequate blood flow
Alpha-2 agonists
What is cyanosis?
Blue/purplish mucous membranes
due to peripheral tissues having low O2 saturation
Indicates SEVERE hypoxia - close to death
(Chow chows are purple anyway)
How does bleeding from surgical site assess cardiovascular function?
Very little bleed could indicate poor circulation/cardiac output/low BP
If there is too much bleeding may need to inform assistant to increase IVFT to counteract and prevent hypovolaemia/hypotension
1ml of blood=1g - weight drapes to see how much fluid to give
How can you assess blood pressure?
Doppler (portable)
Oscillometric method (inbuilt multi-parameter monitor)
What reading doe doppler tell you?
Dogs - Systolic Blood Pressure (SBP)
Cats - Mean Arterial PRessure (MAP)
What are normal BP ranges for a healthy non-anaesthetised patient?
~Systolic 100-160mmHg
~Diastolic 80-120mmHg
~Mean 60-100mmHg)
Important to take BP prior to surgery to establish normal for that patient
How do you know what size cuff to use?
~40% of circumference of area of limb you are placing it on
Advantages of using Doppler
Portable
Easy to use
Constant monitoring
Disadvantages of doppler
Difficult in noisy environment
Incorrect reading if using wrong sized cuff (cats)
If cuff too large - reading is likely lower than true
If cuff too small - reading likely higher than true
Only tells you systolic blood pressure
How do you use a doppler method?
- Cuff in place on patient - above pulse site
- Shave pulse site
- Apply conduction agent to doppler sensor
- Hold doppler sensor over pulse
- Turn volume up on device - ideally wear headphones
- Listen to pulse
- Inflate cuff with pump until pulse sound disappears
- Slowly release pump until noise returns
○ That point on dial is the dogs systolic blood pressure
○ Or cats MAP - Repeat 5-6 times and take average reading
Why is monitoring BP important?
Best information available on tissue perfusion
MAP < 60mmHg for over 30 mins can lead to:
Renal failure
Delayed recovery
Neuromuscular complications
Decreased hepatic metabolism of drugs
CNS abnormalities such as blindness
What is pulse oximetry?
Measurement of % of haemoglobin saturated with oxygen
Should be >95%
SpO2
Tells us about tissue perfusion
Portable or inbuilt into multi parameter monitor
Detects hypoxaemia (low blood O2)
Displays PPG - ‘pleth’
Can show vasoconstriction (height shrinks)
Where can a pulse oximeter probe be placed?
Tongue
Nose
Lip
Pinna
Toe web
Flank
Tail
Achilles tendon
Rectum
Vulva
Advantages of pulse oximetry
- Inexpensive
- Non-invasive
- Well tolerated
- Continuous
- Automatic
- Portable
- Audible
- User friendly
Disadvantages of Pulse oximetry
A pulse oximeter reading of over 95% does not necessarily mean everything is ok
○ May not be hypoxaemic but may be hypoxic
○ Blood can be oxygenated but have insufficient circulation to distribute blood
Important to use pulse oximeter AND blood pressure monitoring
What can cause inaccurate readings of pulse oximetry?
- Vasoconstriction (alpha 2 agonists, hypothermia, shock)
- Hypoperfusion
- Movement
- Hypothermia
- Bright overhead lights
- Smoke inhalation (abnormal haemoglobin)
- Pigmented skin
- Anaemia
- Shock
What does an ECG tell you?
Electrical activity of heart
Heart rate/rhythm
Can detect arrhythmia
