Inotropes
Not to be mistaken with the curriculum item Endogenous regulation of vascular tone
Noradrenaline vs adrenaline
Norad: alpha > beta agonism
- → ↑ SVR
- our fav for sepsis
- ⚠️ reflex bradycardia
Adrenaline: beta > alpha
- our unproblematic fav for arrest, low flow state
- → positive inotropy/chronotropy
- alpha at higher doses preserves coronary and cerebral blood flow?
- second line
- endogenous peptide
- think about shock dose steroids if septic and reaching for the VP
- action: antidiuresis + SVR + platelet aggregation + PVR
also used for varices?? (I guess like terlipressin) and non-nephrogenic DI
metaraminol
our other unproblematic fav - we like it because low potency
alpha 1 agonist
like norad, can cause reflex bradycardia
tachyphylaxis (depletion of norad)
| Other bits | |
|---|---|
| Target receptor | Directly acts on alpha-1 and beta-1 receptors |
| Metabolism | Not metabolised, it seems (not susceptible to COMT or MAO) |
| Elimination | Eliminated slowly over hours/days. Distribution half-life is rapid(minutes). |
| Time course of action | Effect lasts 20-60 minutes |
norad vs metaraminol?
Similar effects to norad
Pulm arterial vasoconstrictor
Giuseppe et al 2005
enoximone
phosphodiesterase inhibitor - inodilator effect
sympathomimetic - alpha and beta agonist action
↑ SV, positive chronotropy, ↓ pulmonary resistance at higher doses
does not affect release of endogenous noradrenaline
tolerance