Cardiorespiratory Flashcards
which lung areas can we localised dyspnoea and tachypnoea to?
upper airway
lower airway
lung parenchyma
pleural space
what does dyspnoea mean?
difficult or laboured breathing
what does tachypnoea mean?
increased rate of respiration
what is orthopnoea?
upright position, extended neck
what is a normal respiratory rate?
<35 breaths per minute at rest
<25/min when asleep
what are the possible causes of tachypnoea and dyspnoea?
physiological cause
hypoxaemia, hypercapnia
respiratory disease
cardiac disease
what physiological factors might contribute to tachypnoea/dyspnoea?
stress, pain, excitement, exercise
what structures form the upper airway?
nasal passages, pharynx, larynx, trachea
what type of dyspnoea usually affects the upper airway?
inspiratory dyspnoea
what type of respiratory noises affect the upper airway?
stertor or stridor
what are some of the upper airway causes of dyspnoea?
laryngeal paralysis
brachycephalic syndrome
neoplasia
polyps
foreign bodies
inflammation
tracheal collapse
what is the immediate treatment for upper airway obstruction?
anaesthesia and intubation
why should patients with upper airway compromise be monitored closely?
decompensation can be rapid
what structures make up the lower airway?
bronchi and bronchioli
what breathing pattern is typical of lower airway obstruction?
quick short inspiration and prolonged expiration
what type of respiratory issues does quick short inspiration and prolonged expiration indicate?
lower airway obstruction
what can we hear on auscultation with lower airway obstruction?
harsh lung sounds - wheezes, crackles
why might wheezes and crackles be heard on auscultation?
bronchoconstriction
secretions blocking airways
what are some of the lower airways causes of dyspoea?
asthma
bronchitis
smoke inhalation
bronchopneumonia
chronic obstructive pulmonary disease
what type of respiratory components can be affected by issues with the lung parenchyma?
inspiratory and expiratory components
what are some of the lung parenchymal causes of dyspnoea?
pulmonary oedema
pneumonia
haemorrhage
contusion
neoplasia
thromboembolism
parasites
what type of breathing pattern is seen with pleural space disease?
restrictive pattern - increased rate but reduced depth of inspiration
why does pleural space disease cause a restrictive breathing pattern?
lungs cannot expand as they should
what are some of the pleural space causes of dyspnoea?
pneumothorax
pleural effusion
masses
diaphragmatic hernia
what are some of the causes of pleural effusion?
haemorrhage
infection (pyothorax)
neoplasia
heart failure
chylothorax
what are the usual findings on auscultation of a patient with a pleural effusion?
muffled heart and lung sounds ventrally but normal lung sounds dorsally
what is our immediate clinical approach to a patient respiratory distress?
oxygen supplementation straight away
physical examination
localise - stridor/stertor?
RR and effort
mucous membrane colour
HR, arrhythmias, murmurs, peripheral pulses
what is the goal of oxygen supplementation in these patients?
increase oxygen content in arterial blood and delivery to tissues - resolution of life-threatening hypoxaemia
relief of respiratory distress
what are the main determinants of oxygen delivery?
haemoglobin concentration
blood concentration
cardiac output
what are the main methods of oxygen supplementation?
flow by
mask
nasal prongs
oxygen catheter
collar
oxygen cage
intubation and ventilation
what is the normal approach to patients displaying signs of pleural effusion/pneumothorax?
diagnose - examine, thoracic radiographs, U/S
stabilise - thoracocentesis
what types of samples might we collect via thoracocentesis?
samples for cytology, culture, biochemistry
what is a safe fraction of inspired oxygen for long term supplementation?
<60%
how can we monitor patients in respiratory distress?
physical examination
arterial blood gas analysis
pulse oximetry
what should we be monitoring during physical examination of patients in respiratory distress?
RR and effort
mm colour
HR and peripheral pulses
anxiety levels
what does arterial blood gas analysis measure?
PaO2 - partial pressure of oxygen
what is the gold standard for evaluation of arterial oxygenation?
arterial blood gas analysis
where should a blood gas sample be taken from?
an artery
which arteries are suitable for blood gas sampling?
dorsal metatarsal, femoral artery
what is important to remember after taking a blood gas sample?
lots of pressure on punctured vessel
analysis should be done ASAP
what is PaO2 dependent on?
oxygen
barometric pressure
what is a normal PaO2 value breathing room air?
100mmHg
what is a normal PaO2 value breathing 100% oxygen?
500mmHg
what PaO2 value is hypoxaemic?
<80mmHg
what does pulse oximetry measure?
peripheral oxygen saturation
what is oxygen saturation indicative of?
haemoglobin saturation
what are the benefits of pulse oximetry?
continuous and non-invasive measurement
what is the relationship between PaO2 and oxyhaemoglobin?
non-linear, S-shaped curve
why isn’t it deal to take thoracic radiographs of an animal in respiratory distress?
restraint for radiographs can exacerbate stress
what side congestive heart failure do dogs commonly get?
can get left and right sided
what commonly causes left-sided heart failure in dogs?
small breeds - myxomatous mitral valve disease
large breeds - dilated cardiomyopathy
what is dilated cardiomyopathy?
weakening of the heart muscle - results in systolic dysfunction
what causes right-sided heart failure in dogs?
pericardial effusion
what causes congestive heart failure in young dogs?
congenital heart disease
what type of heart failure do cats get?
biventricular failure
what commonly causes biventricular heart failure in cats
hypertrophic cardiomyopathy
what happens in hypertrophic cardiomyopathy?
thickening of the heart muscle - leads to diastolic dysfunction
what are the effects of left-sided (backwards) heart failure?
pulmonary oedema
tachynpoea/dyspnoea
cough
what are the effects of right-sided (backwards) heart failure?
effects on body - backs up from pulmonary circulation
distended peripheral veins - esp enlarged jugular
ascites, pleural effusion
how does cardiac ascites/pleural effusion cause tachypnoea/dyspnoea?
presses on diaphragm
what is caused by forward failure of the heart?
reduced cardiac output
what side of the heart is affected by forward failure?
both
what are the effects of forward failure/reduced cardiac output?
weak peripheral pulses due to decreased stroke volume
tachycardia (compensatory)
how does left-sided heart failure result in a cough?
enlarged heart presses on left main bronchus
how does left-sided congestive heart failure present?
heart murmur (not always)
tachypnoea, dyspnoea
tachycardia
pale mm, prolonged CRT
arrhythmias (?)
weak peripheral pulses, pulse deficits (?)
what is the overall clinical approach towards left-sided heart failure?
history
physical examination
stabilisation of patient before performing diagnostic tests
how can we stabilise patients in left-sided congestive heart failure?
minimise stress - consider mild sedation
oxygen supplementation
furosemide IV for pulmonary oedema
pimobendan IV/PO to improve myocardial contractility
how does furosemide help reduce pulmonary oedema in left-sided heart failure?
reduces circulating volume
what drug can be given to help reduce circulating volume?
furosemide IV
which drug can be given to help improve myocardial contractility?
pimobendan (IV/PO)
what diagnostic tests can be done to diagnose left-sided congestive heart failure?
echocardiography
thoracic radiography
ECG
blood pressure measurement
blood tests
what can echocardiography tell us about left-sided heart failure?
diagnosis and severity
what can thoracic radiography tell us about left-sided heart failure?
degree of pulmonary oedema, patterns and distribution of fluid, presence of neoplasia
what can ECG tell us about left-sided heart failure?
presence of arrhythmias
what can BP measurement tell us about left-sided heart failure?
presence of hypotension
what can blood tests tell us about left-sided heart failure?
electrolytes, renal parameters
what should we be monitoring in patients with left-sided congestive heart failure?
RR and effort (goal <40 brpm)
blood pressure (goal >80mmHg systolic)
HR and pulse quality
ECG if known arrhythmias
thoracic radiographs for pulmonary oedema
what are the main signs of patient improvement with left-sided heart failure?
respiratory and heart rate decrease
how should left-sided heart failure be managed one the patient is stabilised?
optimise therapy - life-long
start feeding ASAP to minimise cardiac cachexia
r/v for blood tests, repeat exam and echo etc
why should patients with left-sided heart failure be fed well ASAP?
to minimise cardiac cachexia
what is cardiac cachexia?
loss of body weight and muscle condition due to heart failure
what are some of the causes of right-sided congestive heart failure?
pulmonic stenosis
tricuspid dysplasia
pericardial effusion
how can right-sided heart failure be diagnosed?
history and physical exam
echocardiography
thoracic radiography
ECG
CT
what is heard on auscultation of a patient with right-sided heart failure?
muffled heart sounds
what can echocardiography tell us about right-sided heart failure?
diagnosis and presence of neoplasia
why is it important not to do radiographs alone if right-sided heart failure is suspected?
can be easy to mistake pericardial effusion for enlargement of the heart of radiographs
why might we CT patients with right-sided heart failure?
to determine if cause is neoplastic
what is pericardial effusion?
increased fluid in the pericardium
what is the result of pericardial effusion on the heart?
right atrium collapses due to increased external pressure - filling is impaired and CO is decreased
what is compression of the heart due to pericardial effusion called?
cardiac tamponade
what is cardiac tamponade?
compression of the heart due to pericardial effusion
what are the causes of pericardiac effusion?
can be idiopathic or neoplastic
what is the typical signalment for pericardial effusion?
large-breed adult dogs
what is the first line treatment for pericardial effusion?
pericardiocentesis
IVFT
why are IV fluids given to patients with pericardial effusion?
obstruction to venous return caused by external pressure - fluid can help increase venous return thereby increasing CO
why is it difficult to tell whether the correct area is being drained during thoracocentesis?
pericardial fluid typically looks like blood
how can you tell if fluid drained during pericardiocentesis is pericardial fluid or blood?
wait and see if fluid clots - blood will clot but pericardial fluid won’t
what should we see in the patient post-pericardiocentesis?
improvement of CVS parameters - HR, pulse strength, demeanour
how long should patients be hospitalised after pericardiocentesis? why?
12-24 hours - monitor for arrhythmias and/or recurrence
what is the most common cause of feline cardiac emergency?
hypertrophic cardiomyopathy
what is the typical presentation of hypertrophic cardiomyopathy?
murmur, gallop sound
tachypnoea, dyspnoea, open-mouth breathing
tachy or bradycardia
weak peripheral pulses
hypothermia
where does arterial thromboembolism commonly occur in cats?
distal aorta
what is the most obvious sign of aortic thromboembolism in cats?
sudden-onset hindlimb paresis/paralysis
what are the symptoms of aortic thromboembolism?
pain
pallor/cyanosis (purple) of pads and nail beds
paresis/paralysis
pulselessness
poikilothermy (cold leg)
what is the typical clinical approach to feline cardiac emergencies?
history
physical examination
stabilisation - before further testing!
how can we help stabilise cats in cardiac emergency?
avoid stress!!
oxygen supplementation
furosemide IV/IM for pulmonary oedema
drain pleural effusion
gentle warming
analgesia (for arterial thromboembolism)
what is involved in the diagnostic approach for feline cardiac emergencies?
history and PE
stabilisation
echo and ECG
BP measurements
blood tests
what can echo tell us about feline cardiac emergency?
diagnosis, severity
what can thoracic radiography tell us about feline cardiac emergency?
presence of pulmonary oedema (avoid until patient stable)
what can ECG tell us about feline cardiac emergency?
presence of arrhythmias
what can BP measurement tell us about feline cardiac emergency?
presence of hypotension
what can blood tests tell us about feline cardiac emergency?
electrolytes, renal parameters
how should cats be managed after stabilisation of cardiac emergency?
adjust therapy, offer food - important to get sufficient caloric intake
warm soft bedding and physio for thromboembolism
home ASAP - minimisation of stress (ongoing once home)
how should cats be monitored after cardiac emergency?
re-visit for blood tests, exam, echo
owner to monitor SRR and respiratory effort for signs of thromboembolism
what should cat owners be warned of after cardiac emergency?
some cats can die suddenly
what is the prognosis of feline cardiac emergency?
guarded - can do well
what is a normal HR for a cat/dog?
dog 60-160bpm
cat 160-220bpm
what is classed as bradyarrhythmia?
dog <60bpm
cat <120bpm
what is classed as tachyarrhythmia?
dog >160bpm
cat >240bpm
what is the typical presentation of a patient with an arrhythymia?
syncope/collapse
weakness/exercise intolerance
signs of congestive heart failure
abnormal heart rhythm - irregular, too fast/slow
weak peripheral pulses, pulse deficits
how can we test for arrhythmias?
ECG
what is 3rd degree AV block?
HR 40/min, P and QRS not associated
what is ventricular tachycardia?
HR 300/min, wide and bizarre complexes