Diagnostic Techniques Flashcards
In relation to the ribs, where can the heart be found in dogs?
around the third to sixth rib
How would you position a dog to get diagnostic radiographic images of the heart? (7)
- Lie the dog laterally on the affected side
- Pull fore and hindlimb out of the collation area and tie
- Keep the head in a neutral position
- collimate to the heart
- Capture on inspiration
- lie the dog on its back or sternum, head spine and tail should be in line
- Repeat process
- head spine and tail should be in line
What main structures can be seen on a cardiac radiograph? (5)
- Heart
- Aoritc arch
- Ascending aorta
- Tracheobronchial lymph nodes
- Pulmonary artery
What is angiography?
Special type of radiograph using a contrast media used to visualise blood vessels in and around the heart
When taking thoracic radiography should dogs be anaesthetised, sedated, or left as normal? and Why?
Sedated so they don’t move when the image is taken, unless severely dyspneic, not anaesthesia as it alters lung function, unless totally necessary
What might cause an alveolar patter on a radiograph? (3)
- pulmonary oedema
- pneumonia
- haemorrage (anutoimmune)
What causes bronchial pattern to show up on a radiograph? (2)
- Cells or fluid lining the bronchi
- Cells or fluid in the peribronchial space
What might cause a vascular pattern to be seen on a radiograph?
abnormal amount of blood in the vessel causes a change in position or diameter
What might cause an interstitial pattern on a radiograph? (3)
- nodular - accesses
- nodular - tumours
- diffuse - pleural effusion
What is pneumothorax and how would it look on a radiograph?
collapsed lung
In general how big should the heart be in a canine lateral radiograph?
3.5 rib spaces big
In general how big should the heart be in a canine dorsoventral radiograph?
2/3 the width of the thorax and maximum 6 rib spaces long
What are the limitation of a cardiac radiograph? (3)
- differences in breeds
- inspiration and expiration changes
- movements cause blur
What are the limitation of angiography? (3)
- lesions can be underestimating
- general radiographic issues
- large variation in contrast concentration during systole and diastole
What is pulse oximetry?
non-invasive way of measuring the amount of oxygen in the blood by measuring haemoglobin saturation
What is capnography
The monitoring of PCO2 during anaesthesia
What is a blood gas analyser?
A machine that measures pH, PO2, PCO2 and HCO3-
What are the limitations of capnography? (2)
- The sampled air contains anaesthetic so must be returned to the circuit
- not as accurate as a blood gas analyser
How is a direct arterial blood pressure measurement achieved?
Using a catheter which is inserted into an artery, and the machine plots a graph in real time
How is an indirect arterial blood pressure measurement achieved?
Achieved by palpating the peripheral pulse
What is a doppler flow probe?
ultrasound waves are reflected off pulsing blood vessels and turned into audible sound
What is doppler sphygmomanometry?
Same method as a oscillometric method but uses a crystal to detect blood flow after the uff is released
What is the oscillometric method for measuring blood pressure?
A cuff inflates to a higher pressure than the systolic pressure so that flow stops, when slowly the released, the pressure at which the first blood flow is heard is recorded.
What piece of equipment can be used to measure central venous pressure?
Manometer
How would you prepare and position for a thoracic ultrasound? (5)
- Clip the area
- rub with alcohol
- apply gel
- place in lateral recumbency
- scan both sides
Where would you place an ultrasound probe to view the heart?
palpate the apex beat, place in a rib space, look longitudinal and transverse
What are the limitations of cardiac ultrsound? (2)
- bone
- distance in large animals
What does doppler ultraound show?
Shows the direction of blood flow because a change in frequency occurs when sound is reflected off a moving object. Approaching objects cause a frequency increase and retreating objects show a frequency decrease.
What can M-mode on ultrasound show you?
Cardiac movemet
What are the two most common ultrasound views of the heart?
- right parasternal short axis
- right parasternal long axis
How do you record an ECG in a dog? (4)
- Place in right lateral recumbency
- Spray limbs with alcohol
- Apply gel to areas that the electrodes will be placed
- Apply electrodes to both hind limbs and the right forelimb
What clinical information can you obtain from an ECG? (6)
- AVN function
- SAN function
- Tachycardia
- Bradycardia
- Heart rate
- heart rhythm
