Vasopressors & Inotropic Agents Flashcards
Definition of shock?
Syndrome initiated by acute systemic hypoperfusion, leading to tissue hypoxia and organ dysfunction
How is perfusion affected in hypovolemic shock?
Perfusion is decreased everywhere
How is perfusion affected in sepsis?
Perfusion is just maldistributed
Common conditions that affect hemodynamics?
PE, Ischemic conditions (L or R ventricular infarct), shock states (sepsis, hypovolemia, cardiogenic shock)
What is mean arterial pressure (MAP)?
Average arterial pressure throughout one cardiac cycle
How is mean arterial pressure (MAP) calculated?
MAP = [(SBP-DBP)/3] + DBP
Normal value for MAP?
80-100 mmHg
Clinical use of MAP is for rapid assessment of what?
Circulatory status
Normal values for systemic vascular resistance (SVR)?
800-1200 dyne*sec/cm^5
Clinical use of SVR is for estimation of what?
Vascular tone (constriction vs. dilation)
SVR is a major determinant of what?
Afterload
How can SVR be regulated?
Autonomic Nervous System (ANS) or pharmacological intervention
Normal value for cardiac output (CO)?
4-7 L/min
Determinants of cardiac output?
HR and stroke volume
How to calculate cardiac output?
CO = HR x SV
Clinical use for CO is used to determine the rate of what?
Rate of blood flow pumped by heart
CO is a major determinant of what?
Oxygen delivery (DO2)
How to calculate Cardiac Index (CI)?
CI = CO/BSA
Normal value for CI?
2.5-4 L/min/m^2
Clinical use for CI is used as a more accurate account of what?
Blood flow adjusting for the size of a person
Normal value for central venous pressure (CVP)?
0-4 cm H2O
Normal value for pulmonary arterial pressure (PAP)?
15-25/5-10 mmHg
What does continuous venous oxygen saturation (SvO2) reflect?
Total body balance between O2 delivery (DO2) and O2 consumption (VO2)
Normal value for SvO2?
68-77%
Low values for SvO2 that indicate inadequate DO2 and/or increased O2 consumption?
55-65%
Low values for SvO2 that suggest anaerobic metabolism?
<55%
High values for SvO2?
80-95%
Possible causes of high SvO2?
Increased CO, L to R shunting (back-leak from systemic to pulmonary circulation), inadequate O2 consumption
Monitoring parameters for shock?
HR, BP, Temp, Urine output, Pulse oximetry
What is a common heart rate finding in shock?
Tachycardia (more common due to body trying to compensate/ deliver more O2 to make up for lack of perfusion)
What is a common BP finding in shock?
Hypotension most common
What does temperature help distinguish in shock?
If infection is involved (sepsis)
What is one of the first signs of inadequate perfusion?
Oliguria (abnormally small amounts of urine)
*shows up even before BP or HR changes
What does pulse oximetry measure?
% of hemoglobin in the blood that is saturated w/ O2
Hemorrhagic causes of hypovolemic shock?
Internal bleeding, trauma
Nonhemorrhagic causes of hypovolemic shock?
GI and renal loss, burns, pancreatitis
“Pump failure” causes of cardiogenic shock?
MI, cardiomyopathy
Mechanical causes of cardiogenic shock?
Aortic or mitral valve stenosis, mitral regurg, ventricular septal defect
What is distributive shock?
Maldistribution of blood flow and volume
Causes of distributive shock?
Sepsis, severe sepsis (sepsis + acute organ dysfunction), anaphylactic shock
Cardiogenic shock presentation?
Decrease in CO/CI w/ hypotension not responding to fluid resuscitation
Cardiogenic shock is most likely due to what?
MI/ACS
Septic shock is usually secondary to what?
Infection
Septic shock is driven by what?
Inflammatory response/chemicals
What can occur in septic shock that can cause acute organ failure?
Hypercoagulation
Therapeutic goals for oxygenation in shock?
-Keep hematocrit above 30
-SvO2 >70%
How to keep hematocrit above 30 in shock?
Supplemental O2 via blood transfusions and respiratory assistance (face mask, intubation, etc.)
How to keep SvO2 > 70% in shock?
Blood transfusions/volume, inotropic agents
Therapeutic goals for perfusion in shock?
-SBP > 90 mmHg
-HR < 100 bpm
-CI w/in normal range, prefer if elevated
-Urinary output > 0.5 ml/kg/hr
Reason for keeping HR > 100bpm in shock?
Maintain appropriate BP
How to increase CI during shock to maintain normal levels?
Increase CO w/ inotropic agents, afterload reducers (as long as patient is not hypotensive)
How to keep SBP > 90 mmHg in shock?
Volume, vasopressors, inotropic agents
Administering vasopressors before fluid resuscitation could lead to what?
Profound tissue ischemia and necrosis: compare bn cardiogenic shock vs septic shock ???????
How to keep urinary output > 0.5 ml/kg/hr during shock?
Volume, diuretics, vasopressin, vasopressors (i.e. maintaining adequate BP)
Types of crystalloid fluid used for resuscitation/BP?
Normal saline, lactated ringers
Types of colloid fluid used for resuscitation/BP?
Blood/blood products (Packed RBCs, platelets, fresh frozen plasma), Albumin, Hetastarch (Hespan)
Which is better: colloid or crystalloid fluid for resuscitation?
Data shows no difference in outcomes
Which is used more commonly for resuscitation: crystalloid or colloid fluid? Why?
Crystalloids (20 ml/kg bolus good starting point) - less expensive, no risk of infections as opposed to colloids (ex. hepatitis)
*blood still used to maintain hematocrit/restore any blood loss
Where are V1 receptors found?
Arteries
Where are B1 receptors found?
Cardiac tissue
Where are a1 receptors found?
Arteries
Where are dopamine receptors found?
Arteries
Ratio of receptor agonism for NE?
Predominantly equal balance between a1 and b1 receptors
What is the 1st pharmacological choice to restore pressure after attempts w/ fluids?
NE
Goal systolic pressure w/ NE use?
> 90 mmHg
Start at 1 mcg/min of NE and titrate up to what?
Goal MAP
What are limiting features to NE uptitration?
MC limiting factor: tachycardia
goal MAP vs. comfortability w/o tachycardia
*clinical decision
What is the ratio of receptor agonism of dopamine?
Dopamine R’s (liver metabolizes dopamine into NE –> vasoconstricts)
What is the second pharmacological choice to restore pressure after attempts w/ fluids?
Dopamine (second to NE)
Is dopamine a strong or weak vasoconstrictor?
Weak
Evidence has shown increased risk of what in dopamine when compared to NE?
Side effects
Start dopamine low at 5 mcg/kg/min and titrate up to what?
10 mcg/kg/min
Medium doses are target (don’t typically use low doses)
With dopamine, as the dose increases, what also increases?
Risk of proarrhythmic effects
What is the ratio of receptor agonism of epi?
a and b adrenergic R’s
Evidence suggests that what agent is preferred over epi to restore pressure?
NE
The pharmacology of epi is similar to that of what drug?
NE
What is the drug of choice for anaphylactic shock?
Epi
Which drugs are inotropic and vasopressor agents?
NE, dopamine, epi
Which drugs are vasopressor agents?
Vasopressin, phenylephrine
Which drugs are inotropic agents?
Dobutamine, phosphodiesterase inhibitors,
Mechanism of action of vasopressin is devoid of what?
Adrenergic pharmacology
Vasopressin has no risk of what?
Arrhythmias, tachycardia, etc.
Vasopressin is also known as what?
ADH (Anti-diuretic hormone)
Vasopressin works on what receptors?
V1 R’s
Vasopressin has good effects with increasing what?
Increasing MAP, SVR, & urine output
What is the ratio of receptor agonism for Phenylephrine?
Primarily a-1 R agonist, minimal to no beta-adrenergic activity
What kind of agonist is phenylephrine?
Selective alpha agonist
Phenylephrine has little to no effect on what?
HR
Phenylephrine has no increase in what?
Myocardial oxygen demand
What is usually the last line agent for shock?
Phenylephrine
Is phenylephrine a mild or profound vasoconstrictor?
Profound
What is the ratio of receptor agonism for Dobutamine?
Directly stimulates B-1 R’s of heart
Also a-1
(little activity on B-2, a-2)
What does dobutamine increase?
Cardiac contractility, CO, DO2, and VO2 w/o changing MAP
*Used to increase CI
What can dobutamine cause if fluids aren’t properly resuscitated?
Hypotension (has vasodilatory properties)
Dobutamine is often combined with what other medication?
NE
Which medications are phosphodiesterase inhibitors (class of inotropic agents)?
Milrinone and Amrinone
Phosphodiesterase inhibitors increase cAMP, which has what effect?
Positive inotropic effect, some afterload reduction
Phosphodiesterase inhibitors are commonly used in the setting of what kind of shock?
Cardiogenic shock
In order to be treated with phosphodiesterase inhibitors, what must be at adequate values in patients?
BP
What is the pharmacotherapy approach of the “sepsis bundle”?
Abx + fluid, vasopressors for pressure resuscitation if necessary
When should the sepsis bundle be administered?
Within 1 hour (as opposed to 3/6 hour bundle)
*amplifies urgency and need of care
Stress ulcer prophylaxis?
H2RA or PPI
DVT prophylaxis?
heparin or lovenox (enoxaparin)
If BP is still low (MAP<65) despite fluid and vasopressors, what can be used ?
Physiological replacement doses of hydrocortisone
Glucose control is necessary in sepsis if the levels are greater than what value?
> 180mg/dl
