Drugs to treat shock Flashcards
How does blood get back to the heart?
Sympathetic Nervous system contracting the veins
Blood volume
Muscle pump that squeezes the veins and when they have a 1-way valve to direct blood back to the heart
Preload, Pump function, afterload, and tissue perfusion in Hypovolemic shock
Preload= Pulmonary capillary wedge pressure is decreased
Pump function: Cardiac output is decreased
Afterload: systemic vascular resistance is increased
Tissue perfusion: mixed venous oxygen saturation is decreased
Preload, Pump function, afterload, and tissue perfusion in Cardiogenic shock
Preload: pulmonary capilary wedge pressure increased
Pump function: cardiac output is decreased
afterload: systemic vascular resistance:
- increased
Tissue perfusion: Mixed venous oxygen saturation
-decreased
Preload, Pump function, afterload, and tissue perfusion in distributive shock
Preload: pulmonary capillary wedge pressure
-decreased or normal
Pump function: cardiac output
-decreased
afterload: systemic vascular resistance
- decreased
Tissue perfusion: mixed venous oxygen saturation
-increased
what are the two phases of septic shock?
Distributive
Warm (hyperdynamic): high CO with low TPR due to vasodilation from the effects of histamine, bradykinin, serotonin, endorphins, etc., with leaky capillaries causing fluid shifts into “third spaces”… this is reason large amount of crystalloid fluid resuscitation is always required for septic shock, and is always first-line therapy
Cold: (low-output/high resistance) shock: consequence of profound hypotensions/hypoperfusion; cold mottled skin with petechiae typically appearing first in the feet and moving upward to become essentially irreversible multi-system failure when seen above the knees.
if the patient is hypotensive?
unless due to to cardiogenic shock
give crystalloid (30mL) (%sodium chloride)
want to rise cardiac filling pressure, assessed with jugular venous pressure
- normal <8 cmH20
- during shock want to be at 10-12 cm
What is the treatment for Anaphylactic shock?
Immediate: epinephrine
- B1 to increase myocardual contractillity
- a1 and a2 to increase vascular tone in organs
- B2 to bronchodilate
antihistamine (dihenhydramine, famotidine)
inhaled albuterol
when is it necessary to start to give blood during shock due to blood loss?
loss of 1500-2000mL
(30-40%)
otherwise just need to give fluid
what are some Vasopressors and inotropes for shock?
•
dopamine (DA): precursor to NE, at lower doses it preferentially stimulates β-receptors while higher doses also stimulate α-receptors
•
norepinephrine (NE): stimulates vascular α-receptors and β1-receptors of heart and kidney, but not β2-receptors
•
epinephrine: potent at β1-receptors, also stimulates α-receptors and β2-receptors of vasculature
•
dobutamine: preferentially stimulates β1-receptors of heart to increase rate and contractility, but does vasodilatein periphery
•
phenylephrine: stimulates α-receptors, increase in blood pressure can reflexlydecrease HR and contractility due to withdrawal of sympathetic tone
•
vasopressin: hormone from posterior pituitary
–
a potent vasoconstrictor, it exerts these effects by binding to V1 receptors in the vasculature
(V2 receptors in kidney mediate its antidiuretic effects)
what are the drugs considered for Cardiogenic shock?
both NE and DA are used, NE is apparently superior in cardiogenic shock
giving dopamine also can stimulate renal vasodilation via to D1 receptor
when to use Dobutamine?
used in refractory shock/systolic heart failure when the low cardiac output despite adequate filling pressure
what is the definition and parameters of Sepsis and septic shock
Sepsis: –temperature > 38.3oC or < 36oC –HR > 90 bpm –tachypnea, RR > 20 breaths/min –altered mental status –significant edema –hyperglycemia (plasma glucose > 140 mg/dL) w/o diabetes
Septic shock = sepsis induced hypotension that persists after adequate fluid resusitation
when should you give antibiotics in septic shock
Evidence-based medicine now convincingly supports prompt administration of antibiotics for septic shock… perhaps benefits from fact that inotropes and vasopressors exert immediate effect
blood cultures will be positive in only ~50% of cases of septic shock
what are the vasopressor drugs to be used in septic shock?
–
NE is first-line choice
–
EPI can be added to NE or substituted as first-line choice
–
vasopressin can be added to NE, not a first-line choice
–
dopamine used only as substitute for NE if bradycardia
–
phenylephrine is not recommended unless NE causes arrhythmias or continue to have high CO with low TPR
–
dobutamine is inotropic agent of choice if needed
should a patient with sepsis be given Corticosteroids?
yes but only at low doses have been shown to improve shock reversal
