Myocardial Ischaemia Flashcards
What is the main principle of treatment for intraoperative MI
Reducing oxygen demand and increasing oxygen supply to the myocardium
What is the target HR
60-80bpm
What methods could be used to control the heart rate
Beta blockers - Metoprolol 2.5mg boluses
- Esmolol 0.5mg/kg bolus with 50-200mcg/kg/min infusion
Narcotics
What are the very first steps in managing intraoperative MI
A, B, C Confirm airway, administer 100% oxygen Confirm adequate ventilation, anaesthesia and analgesia Control the heart rate Target normotension
Outline options if the patient is hypertensive
Ensure all stimulation has been ceased Ensure adequate analgesia Pharmacological management - beta blockers Hydralazine GTN infusion
Outline options if the patient is hypotensive
Restore normovolaemia - transfuse blood if anaemic
Treat any inappropriate vasodilation - Anaesthetic induced vasodilation - carefully titrate a vasoconstrictor -> ideally aim to avoid any adverse increase in afterload
Phenylephrine 25-50mcg bolus
Metaraminol 0.5-1mg bolus
What is the ideal blood pressure
Target SBP 100-120 with MAP >75
Once ABCs are corrected and stable, what are the next steps in management
Establish haemodynamic monitoring
Perform echocardiography
Control the coronary filling pressure
Support cardiac contractility - ideally an inodilator (or inotrope)
Commence GTN infusion and support blood pressure
Consider options for definitive management - anticoagulation, placement of IABP, PCI, etc
How is coronary perfusion pressure determined
CPP = ADP - LVEDP
Coronary perfusion pressure = Aortic diastolic pressure - left ventricular end diastolic pressure
- Ideally need to maintain a low LVEDP
How do you make a GTN infusion
50mg GTN in 50mL 0.9% NaCl
Commence at 3-5mL/hr and titrate to response
Monitor for shunt
