Monitoring

Question 1

Formula for blood flow

Answer 1

Flow = Pressure/resistance

Question 2

MAP formula

Answer 2

MAP = DP + (SP-DP)/3

• Systolic blood pressure  indicates cardiac strength
• Diastolic blood pressure  indicates arteriolar tone

Question 3

Formula for pulse pressure

Answer 3

Pulse pressure = SBP – DBP

Question 4

Contraindications to BP measurement

Answer 4

• trauma
• lymphatic drainage
• vascular things eg. AV fistula, indwelling catheter

Question 5

Problems & limitations with BP monitoring

Answer 5

• Pain
• Petechiae / ecchymoses
• Limb oedema
• Thrombophlebitis
• Venous stasis
• Peripheral neuropathy
• Compartment syndrome

Question 6

Bladder dimensions in the BP cuff

Answer 6

• Width  40% of circumference of entire upper arm
• Length  encircle 80% of extremity

Question 7

Advantage of Direct Arterial Blood Pressure monitoring

Answer 7

Advantage is that it gives beat-to-beat monitoring, that it displays a waveform on the monitor, and that arterial blood samples can be taken at regular intervals.

Question 8

Interpretation of waveform of direct arterial BP monitoring

Answer 8

The waveform can be divided into a systolic and a diastolic time.
Systole coincides with the R-wave and starts with a rapid systolic upstroke that reaches the systolic peak pressure, then you will have the systolic decline, and eventually it will end with the dicrotic notch (closure of the aortic valve).
In diastole, it coincides with the T wave. You have a diastolic runoff which then ends with an end-diastolic pressure.

**Go look at a diagram with labels

Question 9

What conditions would alternate the wave pattern? And how would they alternate it?

Answer 9

1. Aortic stenosis
   Pulsus parvus = narrow pulse pressure
   Pulsus tardus = delayed upstroke
2. Aortic regurgitation
   Bisferiends pulse = double peak
   Wide pulse pressure
3. Hypertrophic cardiomyopathy
   Spike-and-dome pattern = midsystolic obstruction
4. Systolic left ventricular failure
   Pulsus alternans = alternating pulse pressure amplitude
5. Cardiac tamponade
   Pulsus paradoxis = exaggerated decrease in systolic pressure during spontaneous inspiration

Question 10

Contraindications to Direct Arterial BP

Answer 10

1. Local infection
2. Coagulopathy
3. Proximal obstruction
   - Coarctation
   - Congenital anomalies of aortic arch vessels
   - Thoracic outlet syndrome
4. Raynaud’s syndrome and Buerger diseases (thromboangiitis obliterans)
   - No radial / brachial arterial cannulations
5. Surgical considerations
   - Mediastinoscopy  right radial (innominate artery occlusion)
   - Lateral decubitans  downward arm
   - Descending aortic aneurysm  right-sided (occlusion of left subclavian artery)

Question 11

Problems & limitations to direct arterial BP

Answer 11

• Infection
• Haemorrhage
• Thrombosis + distal ischaemia
• Skin necrosis
• Embolization
• Haematoma + neurologic injury
• Late vascular complications
• Inaccurate measurements

Question 12

Central venous pressure principles of the waveform

Answer 12

• There are three positive reflections = a, c, and v
• There are two negative reflections = x and y

Systolic components:
- C-wave = closing & bulging of tricuspid valve
- X-descent = atrial relaxation
- V-wave = passive filling of atrium

Diastolic components:
- Y-descent = opening of tricuspid valve
- A-wave = atrial contraction

Question 13

Name a condition and how it affects the Central Venous Pressure

Answer 13

1. A fib:
   Loss of a-wave
   Prominent c-wave
2. Atrioventricular dissociation
   Cannon a-wave
3. Tricuspid regurgitation
   Tall systolic c-v wave
   Loss of x-descent
4. Tricuspid stenosis
   Tall a wave
   attenuation of y descent
5. R Ventricular ischaemia
   Tall a- and v-waves
   Steep x- and y-descents
   M or W configuration
6. Pericardial constriction
   Tall a- and v-waves
   Steep x- and y-descents
   M or W configuration
7. Cardiac tamponade
   Dominant x-descent
   Attenuated y-descent

Question 14

what procedures uses CVP

Answer 14

• Central venous pressure monitoring
• Pulmonary artery catheterization and monitoring
• Transvenous cardiac pacing
• Temporary haemodialysis
• Aspiration of air emboli
• Sampling site for repeated blood testing

Question 15

Contraindications to CVP

Answer 15

• Coagulopathies
• Newly placed pacemaker / ICD
• SVC syndrome

Question 16

Mechanical complications of CVP

Answer 16

• Nerve injuries (brachial plexus, stellate ganglion)
• Arterial injury with haematoma
• Haemothorax / pneumothorax / chylothorax / hydrothorax
• Embolism (air)
• Arrhythmias
• Catheter or wire shearing
• Right atrial / right ventricular perforation

Question 17

Infectious complications of CVP

Answer 17

• Sepsis
• Endocarditis
• Venous thrombosis / pulmonary embolism