7.2 Cardiogenic Shock and Cardiac Assistive Devices Flashcards
Extracorporeal Membrane Oxygenation (ECMO)
Cardiopulmonary Bypass (CPB)
- Highly invasive high risk technology
- Alternate therapy to CPR
- Involves circulatory support and oxygenation of patients blood
- Gas exchange takes place in artificial lungs
Cardiopulmonary Bypass
- Used for operations but can also help in patients who cannot wean from ventilators or require cardiopulmonary support
- Blood is taken from veins, pumped through a membrane oxygenator (where gas is exchanged) then returned to arterial femoral circulation.
- Heating mechanism in the pump is used to maintain body temperature
Advantages/Disadvantages to the Above
ADVANTAGES
- Rapid deployment without need of surgical intervention
- Provides hemodynamic stability
- Allows more time for further assessment and intervention during episodes of acute hemodynamic decompensation
DISADVANTAGES
- Needs continuous anticoagulation
- Unable to provide extended circulatory support
Contraindications
- Occlusive peripheral vascular disease
Cardiogenic Shock
- Decreased CO leads to inadequate tissue perfusion
Manifestations
- Symptoms of HF
- Shock
- Hypoxia
Management
- Correct Underlying Problem
- REDUCE PRELOAD/AFTERLOAD TO DECREASE CARDIAC WORKLOAD
- Improve oxygenation (restore tissue perfusion)
- Monitor hemodynamic parameters, fluid status, and adjust medication according to assessment data
Medications
- Diuretics
- Positive Inotropes
- Vasopressors
Circulatory Assist Devices
- Intra-Aortic Balloon Pump (IABP)
Intra-Aortic Balloon Pump Counterpulsation
IABP Counterpulsation
- Increases coronary artery perfusion and blood flow during diastole by inflation of a balloon in thoracic aorta. The balloon deflates before systolic ejection to decrease afterload.
- Inflation and deflation counter pulse each heartbeat
Results
- Increases coronary artery perfusion and decreases afterload. This increases cardiac output
Goals
- Increase oxygen supply to myocardium
- Decrease Left Ventricular (LV) Work
- Improves CO
Cardiogenic Shock Implications
- Reduces afterload by augmenting perfusion pressure and decreasing workload of left ventricle.
- Good for patients who suffer acute MI with left ventricular heart failure
IABP
- Improves aortic root pressure during diastole
- Increases coronary artery perfusion
- Decreases myocardial oxygen demand
- Increases oxygen supply
- Decreases excessive preload
- Improves contractility
Physiologic Effects of IABP
- Faster heart rates causes shorter diastole with little change to systole
- Rapid heart rates increase oxygen demand with little time for oxygen delivery
- If stroke volume cannot be increased the body naturally increases HR to maintain cardiac output which is costly on oxygen demand
- IABP helps to increase stroke volume and decrease afterload
- This causes tachycardia to diminish
Inflation and Deflation of Balloon
Inflation
- Increases aortic diastolic pressure
- Increases aortic root pressure
- Increases coronary perfusion pressure
- Increases Oxygen supply
Deflation
- Decreases aortic end-diastolic pressure
- Decreases impedance (resistance) to ejection
- Decreases afterload
- Decreases oxygen demand
Ventricular Assist Device
- Used for intractable HF
Indications
- Severe/Acute Left Ventricular Function post MI or surgery
- End stage HF
- Bridge until transplant
Complications
- Bleeding
- Thromboembolic Events
- RVF (Right Ventricular Failure)
- Infection
- Dysrhythmias
- Nutritional Deficits
Impella
- Mini ventricular assist device (VAD)
- Pulls blood from left ventricle into ascending aorta at 2.5 L/min
- Inserted through femoral artery into the left ventricle
- Camera can be placed for heart evaluation (not in real time)
MANAGEMENT
- Monitor cardiovascular system
- VS
- HR and Rhythm
- Monitor Pulmonary and Renal Systems
- Monitor equiptment
- Monitor labs
Inodilators
- Dobutamine and Milrinone
- Both positive inotrope and vasodilator
Action
- Increases contractility and decreases afterload (increases CO)
- Increases forward flow, decreases left ventricular end-diastolic pressure
Dopamine
- Increases renal perfusion
- Improves diuresis
Nitroprusside/Hydralazine
- Reduces afterload
- Controls blood pressure
Nesiritide
- Reduces afterload
Inotropes
- Dopamine, Dobutamine, Epinephrine, Vasopressin, Isoproterenol, Norepinephrine
- Increases force of myocardial contraction and CO
- Used for myocardial contractility issues and cardiogenic shock
Dobutamine
- Used for left ventricular dysfunction (increases contractility and renal perfusion)
Dopamine
- Low dose with loop diuretics help preserve renal function and diuresis (improves renal blood flow)
- When patient is not hypotensive, also use vasodilators for acutely decompensated heart failure.
Inodilators
- Stimulates Beta-Adrenergic receptors in heart/blood vessels to increase contractility and vasodilate.
- Most common are dobutamine and milrinone.
- THEY ARE ALSO CHRONOTROPES SO TITRATE SLOWLY IN PATIENTS WITH TACHYCARDIA OR VENTRICULAR DYSRHYTHMIAS
Phosphodiesterase II Inhibitors
- Milrinone
- Decreases preload and afterload
- Causes hypotension and increases risk of dysrhythmias
Vasodilators
- Nitrates, Sodium Nitroprusside, Nesiritide, Clevidipine
- Decrease preload and afterload
Nitroprusside - MOST RAPID ONSET WITH SHORTEST HALFLIFE
- Given continuous drip
- Requires blood pressure monitoring
IV or ORAL Hydralazine
- Vasodilator (decreased afterload)
- NO NEGATIVE INOTROPE EFFECTS
ACE Inhibitors
- Increases cardiac output and decreases sodium retention, blood pressure, CVP (central venous pressure), SVR, pulmonary vascular resistance, pulmonary capillary wedge pressure
Intropes
- Affect contraction of the heart
Positive
- Increases contractility
- Ventricles empty more completely thus increases cardiac output
- Dopamine, Digoxin, Epinephrine
- Sympathetic Drugs
Negative
- Decrease Contractility Force
- Parasympathetic Drug
- Betablockers, Quinidine, Lidocaine
Chronotropic
- Affects HR
Positive
- Increases HR by accelerating rate of impulses in the SA node
- Sympathetic Drug
- Epinephrine, Atropine, Dopamine
Negative
- Slow down heart rate by decreasing impulses in the SA node
- Acetylcholine, Digoxin, Beta Blockers
Dromotrope
- Affect conduction velocity from SA to AV node
Positive
- Increases velocity of conduction
- Sympathetic Drug
- Phenytoin
Negative
- Decreases velocity of Conduction
- Parasympathetic Drug
- Digoxin, Beta Blockers, Acetylcholine, Verapamil
Medications
Inodilators (Dobutamine, Milrinone)
- Increases contractility
- Decreases afterload (vasodilator) which increases CO
- Increases forward flow and decreases left ventricular end-diastolic pressure
Dopamine - Increase renal perfusion and improves diuresis
Nitroprusside - Reduces afterload and blood pressure control
Nesiritide - Reduces afterload
Hydralazine - Reduces afterload and blood pressure control
Inodilators
- Most common is Dobutamine and Milrinone
- Both increase beta adrenergic receptor stimulation
- They are also chronotropic (increase HR) so titrate carefully in patients with tachycardia or ventricular dysrhythmias
Dobutamine
- Used for patients with left ventricular dysfunction and increases contractility and renal perfusion
