Cardiorespiratory Flashcards
define dyspnoea
difficult or labored breathing
define tachypnoea
increased rate of of respiration
define orthopnoea
upright position with extended neck
what is normal respiratory rate when resting?
<35 brpm
what is normal respiratory rate when sleeping?
<25 brpm
what are the main causes of tachypnoea/dyspnoea?
physiological
hypoxaemia
hypercapnia
respiratory disease
cardiac disease
what are the physiological causes of tachypnoea/dyspnoea?
stress
pain
excitement
exercise
what is hypoxaemia?
not enough oxygen in the blood
what makes up the upper airway?
nasal passages
pharynx
larynx
trachea
what type of dyspnoea is associated with upper airway issues?
inspiratory dyspnoea
what is inspiratory dyspnoea?
hard for the patient to breathe in
what sounds may be heard with inspiratory dyspnoea?
stertor
stridor
what is stertor?
snoring
what is stridor?
harsh, high pitched breathing sounds on inspiration
what conditions are stertor and stridor commonly seen with?
stertor - BOAS
stridor - laryngeal paralysis
what are the upper airway causes of dyspnoea?
laryngeal paralysis
BOAS
neoplasia
polyps
FB
inflammation
tracheal collapse
how should upper airway causes of dyspnoea be treated?
if obstructed: anaesthesia and intubation
decompensation may be rapid
what makes up the lower airway?
bronchi
bronchioli
what respiratory pattern is seen with lower airway dyspnoea?
quick short inspiration
prolonged expiration
what may be heard on lung auscultation of lower airway dyspnoea patients?
harsh lung sounds (wheezing, crackles)
what are harsh lung sound on auscultation caused by?
bronchoconstriction
secretions blocking airways causing crackles as air forced past
what are the lower airway causes of dyspnoea?
asthma
bronchitis
smoke inhalation
bronchopneumonia
COPD
what dyspnoea type is seen with lung parenchyma disease?
inspiratory and expiratory
what are the lung parenchymal causes of dyspnoea?
pulmonary oedema (cardiac or non cardiac)
pneumonia
haemorrhage
contusion
neoplasia
thromboembolism
parasites
what are the cardiac causes of pulmonary oedema?
CHF
what are the non-cardiac causes of pulmonary oedema?
electrocution
strangling
what breathing pattern is seen with pleural space diseases?
restrictive pattern
increased rate but reduced depth
why is restrictive dyspnoea seen with pleural space diseases
lungs cannot expand due to fluid/air leading to shallower breaths
what are the pleural space causes of dyspnoea?
pneumothorax
pleural effusion
masses
diaphragmatic hernia
what are the causes of pleural effusions?
haemorrhage
infection (pyothorax)
neoplasia
heart failure
chylothorax
what are the auscultation findings in patients with effusions?
if standing: muffled heart and lung sounds ventrally (fluid settling)
normal dorsally
what are the auscultation findings in patients with pneumothorax?
muffed heart and lung sounds dorsally as air rises
what is involved in initial assessment of respiratory emergencies?
oxygen is crucial
targeted physical exam
check for URT signs
RR rate and effort
MM
heart rate
any arrhythmias
murmurs
check peripheral pulses (defecits)
what is the goal of oxygen supplementation?
increase oxygen content in arterial blood and delivery to tissue
what are the determinants of oxygen delivery?
haemoglobin concentration
blood oxygenation
cardiac output
how does haemoglobin concentration determine oxygen delivery?
oxygen carrying capcity reduced if haemaglobin reduced (e.g. anaemia)
how does cardiac output determine oxygen delivery?
reduced leads to reduced oxygen delivery to tissues
what are the main methods of oxygen supplementation?
flow by
mask
nasal prongs
oxygen catheter
collar (not ideal)
oxygen cage
intubation
ventilation
how is pleural effusion / pneumothorax diagnosed?
physical exam
thoracic xray
ultrasound
what are the benefits of ultrasound for respiratory patients?
less stressful
no need to be in lateral
what can be used to stabilise pleural effusion/pneumothorax patients?
thoracocentesis
what is involved in thoracocentesis?
sedate animal
prep area
use catheter to drain chest
collect samples for cytology, culture and biochem
what catheters may be used for thoracocentesis?
catheters for dogs
butterfly needle for cats
what are the main considerations for oxygen administration?
is supplementation indicated
awareness of O2 toxicity
rate of delivery needed (not too much or too little)
what are the aims of oxygen supplementation?
resolution of life threatening hypoxaemia
relief of respiratory distress
what are the lungs vulnerable to when patients are on high FiO2?
oxygen toxicity
what influences oxygen toxicity?
FiO2 and duration
when are patients only likely to receive 100% FiO2?
intubated or ventilated
how what FiO2 should patients be on if on long term oxygen?
<60%
what can be done to avoid oxygen toxicity?
administer to lowest level the patient will tolerate
what are the main patient monitoring methods available for dyspnoeic patients?
physical exam
ABG
pulse ox
what is the downside of monitoring patients through physical exam?
insensitive
what should be monitored on a clinical exam of respiratory patients?
RR and effort
MM
heart rate
peripheral pulses
anxiety levels
what may be indicated by mm colour?
dehydration
hypovolaemia
hypotension
vasoconstriction
why may respiratory patients be hypotensive/vasoconstricted?
cardiac output reduced
are mucous membranes necessarily a good indicator of respiratory patient status?
could be normal
what is measured by ABG?
PaO2
what is the gold standard method of evaluation of arterial oxygenation?
ABG
where are ABG samples taken from?
dorsal metatarsal artery
femoral artery
what is needed for ABG?
specific syringe
blood gas analyser
what is crucial about ABG samples to ensure PaO2 is measured accurately?
airtight
analysed straight away
what is normal PaO2 on ABG at room air?
100 mmHg
what is normal PaO2 on ABG at 100% O2?
500mmHg
what does PaO2 depend on?
FiO2
barometric pressure
what PaO2 suggests hypoxaemia?
<80 mmHg on room air
what O2 saturation suggests hypoxaemia?
<95%
what PaO2 is indicated by SpO2 of <90%?
<60 mmHg
how much does PaO2 increase by on 100% FiO2?
~5x room air
why are venous PaO2 readings less useful?
venous PaO2 around 40mmHg once O2 has been delivered to tissues
on room air what PaO2 should you aim for?
80-120 mmHg
on room air what SpO2 should you aim for?
95-100%
what does pulse oximetry measure?
peripheral oxygen saturation
what is calculated by a pulse ox?
haemaglobin oxygen saturation
is the reationship between PaO2 and SpO2 linear?
no
what is the issue with thoracic radiographs?
dangerous if patient is unstable
requires lateral recumbancy
could lead to rapid decompensation
what is congestive heart failure caused by?
increased pressure in the heart leading to increased pressure in veins returning to the heart
this creates increased pressure in the capillaries which prevents fluid from being reabsorbed from the tissues
what types of CHF are seen in dogs?
left sided
right sided
congenital
what signs are seen with left sided CHF?
pulmonary veins
pulmonary oedema
what can lead to left sided CHF in small dogs?
myxomatous mitral valve disease
what can lead to left sided CHF in large dogs?
DCM
what happens to the heart muscle during DCM?
muscle becomes weakened
what part of the cardiac cycle is affected by DCM?
systolic failure - heart not strong enough to pump
what signs are seen with right sided CHF?
systemic veins affected
effusions / ascites seen
what can right sided CHF lead to?
pericardial effusion
what are the sings of CHF in cats?
both left and right sided can be seen
what side of the heart is commonly more affected in cats?
left
what is the most common heart disease in cats?
hypertrophic cardiomyopathy
what is the effect of hypertrophic cardiomyopathy on the cardiac cycle?
diastolic dysfunction due to thickening of heart muscle - heart cannot fill
what are the two types of backward CHF?
left sided
right sided
what organ is most affected by left sided CHF?
lungs
what are the signs seen in the lungs of left sided CHF?
pulmonary oedema
tachypnoea
dyspnoea
cough
how does left sided CHF lead to cough?
cough receptors are in large airways and so unlikely affected by pulmonary oedema
more likely that enlarged heart is triggering receptors
what area is most affected by right sided CHF?
body
what signs are seen with right sided CHF?
distended peripheral veins
ascites
pleural effusion
what are the respiratory effects seen as a result of pleural effusion / ascites?
tachypnoea / dyspnoea due to restriction of breathing
what is forward CHF?
reduction in cardiac output
when is forward CHF often seen?
endstage disease - especially DCM
what side of the heart can be affected by forward failure?
left or right
what are the signs of forward CHF?
weak peripheral pulses
tachycardia
why does forward CHF lead to weak peripheral pulses and tachycardia?
reduction in stroke volume leads to increased heart rate in an attempt to increase cardiac output
how do patients with left sided CHF present?
heart murmur
tachypnoea
dyspnoea
tachycardia
pale
prolonged capillary refill time
arrhythmias
weak peripheral pulses
pulse defecits
are heart murmurs always seen with left sided CHF?
most but not all
can have murmur and no CHF but can have CHF with no murmur