Cardiovascular disease and Anaesthesia Flashcards
What are the anaesthesia concerns in a patient with hypertension
- Cerebrovascular events
- Myocardial ischaemia/infarction/failure
- Renal failure
- End organ damage: encephalopathy
How does the risk of a well controlled hypertensive compare to a non-hypertensive
Normal risk
What should be done if the DBP > 120
Postpone elective surgery for 2 weeks
How long does it take for left ventricular remodelling and normalisation of the shifted auto-regulatory curve?
> 6 months
How does the intra-operative course of the anaesthetic in patients different in patients with hypertension
EXAGGERATED SWINGS BP can be precipitated by SNS stimulation (Intubation / Surgery), Vasodilation and blood loss
What is the influence of antihypertensive medications on the anaesthetic
Diuretics: fluid depletion and electrolyte disturbance
BB: Neg inotropy and neg chronotropy -> low CO
CCB: hypotension
ACEI: Exaggerated intra-operative hypotension and irritable airways
How should BP be managed intra-operatively
Within 25% of starting value (avoid the ‘alpine trace’)
- pre-empt noxious stimuli (intubation)
- adequate analgaesia
- avoid light plane of anaesthesia
What is the mortality of perioperative MI
50%
Which patients with IHD can be considered to have a normal perioperative risk
- CABG within 5 years and is symptom free
2. Walk > than 2 flights of stairs without stopping
Which patients have moderate increased risk
Stable angina
Poor effort tolerance
Which patients are at extremely high anaesthetic risk
Unstable angina Recent MI (< 6 month)
How long should elective surgery be postponed for after MI
at least 6 months
Which patients should always be discussed with/referred to cardiology prior to anaesthesia
Patients who have a coronary artery stent
- Big risk of stent occlusion if clopidogrel is inappropriately stopped
- this depends on the type of stent and when it was placed
Summarise the perioperative management of a patient with ischaemic heart disease
Principle: DO everything possible to maintain autonomic stability i.e. fluctuations in BP and HR.
NB
- Continue meds preop (BB) and provide anxiolysis
- Use Regional
- Avoid NSAIDS (CVEs)
- Blunt intubation
- Monitor closely intraop and post op
What are the principles for intra-operative management for a patient with aortic stenosis
PREVENT DECREASED SVR and keep SLOW HR
Fixed CO = SV cannot increase
- SVR must be maintained (If not –> hypoperfusion brain and heart)
- Slower HR (ensures coronary perfusion)
- Spinal and epidural anaesthesia are contra-indicated
What are the principles for intra-operative management or a patient with aortic regurgitation
FULL, FAST, FORWARD
(Adequate preload, 80 - 100bpm, Decrease SVR)
Reduce time for regurgitant flow
Reduce force pushing regurgitant flow
What is the key difference between the management of AS vs AR
AS
- maintain SVR to ensure perfusion heart and brain
- Slower HR to allow time for coronary filling
AR
- drop SVR to reduce regurgitant flow
- faster HR to reduce time for regurgitant flow.
What are the principles for intra-operative management of Mitral Stenosis
SLOW HR (Rx dysrhythmia aggressively) to keep LA pressure low
Avoid tachycardia and dysrhythmia (AF)
Increased HR –> decreased diastolic time –> diminished ventricular filling –> pulmonary oedema + reduced CO.
AF –> loss of atrial systole/’kick’ which reduces LV filling –> increased LAP –> pulmonary oedema
What are the principles for intra-operative management of Mitral Incompetence
FULL, FAST, FORWARD but avoid fluid overload
Digoxin –> keep K over 4mmol/L
INR < 1.5 before surgery
Summarise the intra-operative management of the various valvular heart lesions
AS - Sustain SVR | Slow HR (Perfuse coronaries/brain)
AR - ‘Rapid’ HR | Reduce SVR (Full, fast, forward)
MS - Slow HR | Sustain SVR (LAP + Pulm. Oedema)
MR - ‘Rapid’ HR | Reduce SVR (Full, fast, forward)
‘Rapid’ = R memory aid for “Regurgitant lesion” = 80 - 100 bpm.
Describe perioperative management for patients in cardiac failure
- Postpone until out of failure if possible
- Rx cause of failure and optimise medical Rx
- Maintain preload (CVP/US/SVV/PPV/leg raise)
- Maintain inotropy (Avoid myocardial depressants)
- hypoxia/hypercarbia/acidosis - Reduce afterload
- Use regional (caution with neuraxial)
What are the common causes of intra-operative dysrhythmias
- Pain
- Hypoxia
- Hypercapnoea
- Electrolytes
- Drugs
Describe intra-operative management of dysrhythmia
ACLS algorithms
- Unstable: Electrical cardioversion
- Amiodarone 300mg over 1 hours (or 10 mins if relatively unstable)
What should be done if a pacemaker is identified in a patient preop
IS THE DEVICE AN IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR PACEMAKER?
- diathermy might cause shock and lethal dysrhythmia
Obtain details:
- date of insertion
- indication for insertion
- current function/dysfunction
- last technologist visit (within 1 year is ok for elective surgery)
ECG may show pacing spikes if patient is pacing-dependent
What type of diathermy is preferable in patients with pacemakers and what if this type of diathermy is not available
BIPOLAR DIATHERMY preferred
If unipolar only –> the diathermy plate must be placed as far away from the pacemaker as possible
When are magnets used on pacemakers
Some pacemakers allow for a magnet to switch the pacemaker over to ‘VOO’ mode which is a fixed rate.
- only do this if you are aware that this is the magnets effect and if the patient is hemodynamically stable
