– vasoconstrictors: epi, NE, AngII, TxA2, vasopressin – vasodilators: PGI2, NO, adenosine, natriuretic peptides
Normal reflex mechanisms
• Increase preload: Na/H20 retention, RAAS • Increased contractility: adrenergic outflow (NE) • Increased afterload: norepi, AngII, endothelin, vasopressin
Contractility
• Increased contractility will provide increased stroke volume/CO for a given level of preload and afterload • Chronic HF patients have high circulating levels of catecholamines and are less responsive to adrenergic stimuli
Lower pcwp ( preload) with nitrates, diuretics
CI 2.2
Subset III:
Subset IV:
0
18
PCWP Mortality increases from set to set! See figure 13-7 in text.
Subset Two
Typical Dosage/Administration
• Protect from light • Stable in D5W or NS in GLASS or special container • Special “nitro” tubing, avoid filters • Check for infusion incompatabilities • 5 to 10mcg/min initially • Titrate up to about 200mcg/min as continuous IV infusion
The Big Picture in Failure
Veins Preload
Heart
Arteries Afterload Need constriction to maintain pressure
Contractility
Need volume to increase stretch, Frank Starling
• Typically involves diuretics, nitrates and (more recently) nesiritide.
Nitroglycerine
• • • • Preferred preload reducer Decreases PCWP, decreases pulmonary congestion Cheap, short T50, easily titrated Used in combination with inotropes in patients with pulmonary congestion and reduced LV function • Coronary dilation at high doses: useful in patients with ischemia • Avoid if elevated intracranial pressure • Tolerance in 12 - 72 hours
It is important to relax!
• Remember that coronary arteries fill during diastole • Remember that filling during diastole contributes to stroke volume (Starling) • Remember that increasing heart rate decreases ventricular and coronary filling, upsets calcium processing by SR, O2 demand increase • Chronic HF patients have typically maxed out preload, and do not have the reserve that you do
CI
2.2 0
STD treatment/monitoring
Subset III:
Subset IV:
18
PCWP Mortality increases from set to set! See figure 13-7 in text.
Subset One
• • • • Patient symptomatic Warrant full work-up Address other cause Maximize oral therapy dilation: 5-10min, prostaglandin mediated • Diuresis: 20+ minutes • Reduction in preload in patients with volume depletion or decreased diastolic function may be harmful • Does not improve CI/CO in most patients (curve flat) • Role: use carefully to reduce symptoms of congestion without compromising cardiac output
– slams the screen door before all the kids get out
• Chronic HF patients are very succeptable to increases in afterload
Approach to patient
• Assess status: s/s, target organ damage • Address alterable causes
• • • • • • Vital signs Acid/base Oxygenation Hydration Renal function Swan line
– PCWP – Cardiac output
Approach by hemodynamic subset
Subset I: perfusing, no pulmonary edema Subset II:
– – – – ACEI BB Diuretics Dig
• Misc.: vaccines, smoking cessation, diet, education, etc…..
Approach by hemodynamic subset
Subset I: Subset II: perfusing, but with pulmonary edema
– receptor downregulation
• Catecholamines cardiotoxic? Necrosis/apoptosis? Arrhythmias?
Afterload is double edged sword
• Increased SVR is important for maintaining MAP • Increased afterload will reduce stroke volume
Other Diuretics
Loop diuretics
• Furosemide (Lasix)
– – – – – – – – – IV (40mg/5ml), IM, PO Bioavailability poor/variable Stable in LR, D5W or LR Typically 40mg – 80mg IVP over 1-2 min Repeat every 1-2 hours as needed Monitor hemodynamics Monitor I/O for measure of net fluid loss Administer potassium as needed in fluids Ototoxicity, allergy possible
Acute HF/Cardiogenic shock
MI
HTN
MI
Death
I
II
Heart Failure
III
IV
Drugs
Valve Dz
Shock
Relationships/Key Terms
• • • • • • Cardiac output= HR x Stroke volume MAP= CO x SVR Preload Contractility Afterload Frank-Starling relationship
• Patient perfusing at expense of higher pressure • Gradually lower PAOP without causing adverse effects
– Avoid over-shooting or else! – Avoid prompting reflex mechanisms
Why is this important?
• • • • HF common diagnosis Hospitalizations are common Associated costs are astronomical Pharmacists will routinely be involved in preparing and dispensing to ICU/CCU • Use of the drugs is frequently in urgent/emergent situations