Hemodynamics and Shock Lecture Powerpoint Flashcards
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Shock definition
Physiologic state characterized by significant reduction in systemic tissue perfusion resulting in decreased oxygen delivery to the tissues, cellular hypoxia and derangement of local and eventually systemic biochemical processes
Mean arterial blood pressure (avg between systolic and diastolic)=
Cardiac output =
Stroke volume =
- CO x SVR (systemic vascular resistance)
- HR x SV
- EDV-ESV
Systemic vascular resistance definition and what two things determine it
Refers to resistance to blood flow offered by all of the systemic vasculature (not the pulmonary), determined primarily by changes in vessel diameter and blood viscosity
Starling’s law
Amount of tension put on the ventricles by the filling of blood will correlate to the contractility generated by the ventricles
-pressor drugs
Increase inotropic effect (contractility) when heart failing to deliver proper cardiac output
Ejection fraction =
-SV/EDV
Increased afterload will decrease ___ from the heart causing, over time, for the heart to ____
Stroke volume, hypertrophy
5 categories of shock
- Cardiogenic (heart muscle problem)
- hypovolemic (due to hemorrhage or hypovolemia)
- anaphylactic (allergic mediated third space sequestering)
- septic (blood stream infection)
- Neurogenic (caused by damage to NS regulation)
2 primary drugs for cardiogenic shock
Intense inotropes such as
- Dopamine
- dobutamine
Dopamine at small, medium, and large doses effects
- Small renal vasodilation
- Medium increased inotropy of heart
- Large increase peripheral vascular resistance (vasoconstrict)
Common causes of cardiomyopathy (3)
- viral infection
- alcohol induced
- pregnancy
Beck’s triad
3 medical signs associated with cardiac tamponade
1) hypotension
2) JVD
3) muffled heart sounds
During pneumothorax tracheal shift occurs to the ___ side
Contralateral
Specific treatment to deal with cellular and mitochondrial poisons such as carbon monoxide
O2 saturation at a dive chamber
4 Stages of shock
1) begins with inciting event
2) local then systemic circulatory abnormality
3) homeostatic mechanisms attempt to compensate until they are overwhelmed
4) progression culminates in irreversible end organ damage or death
Preshock characteristics
Rapid compensation for diminished tissue perfusion by various homeostatic mechanisms, may be asymptomatic despite a 10% reduction in total effective arterial blood volume, eventually become tachycardic, see peripheral vasoconstriction, and modest changes in blood pressure
Shock chracteristics
-Symptoms of organ dysfunction appear, tachycardia, dyspnea, restlessness, metabolic acidosis, cool or clammy skin
Cardinal findings of shock (5)
- hypotension (dropped more than 40mmHg)
- oliguria
- mental status changes
- cool clammy skin
- metabolic acidosis
End organ dysfunction characteristics (2)
- urine output declines
- restlessness evolves to agitation and coma
Suggestive findings of hypovolemic shock (4)
- vomiting
- poor skin turgor
- dry mucosa
- decreased JVD
Suggestive findings of cardiogenic shock (5)
- dyspnea
- chest pain
- palpitations
- pulmonary edema
- elevated cardiac biomarkers or ischemia on EKG
Suggestive findings of “distributive” shock (anaphylactic, septic, neurogenic) (6)
- cough
- hematuria
- chills
- diaphoresis
- rash or hives
- tachycardia
SIRS
Systemic inflammatory response syndrome, extreme physiological reaction to trauma, burns, or other things characterized by tachycardia, fever, rapid respiration, and abnormal WBC count that when in the presence of infection can result in sepsis
Management of shock 4 principles
- stabilize respiration
- assess perfusion
- restore perfusion
- identify and control source of shock
- Low preload requires…
- high preload requires…
- Increased SVR requires…
- Decreased contractility requires…
- …fluids
- …diuretics/venodilators
- …BP reduction (ACEI or ARB)
- …Positive inotropic agents such as dopamine, dobutamine, epi or norepi
Increasing preload has what effect on contraction strength?
Increasing afterload has what impact on stroke volume?
- Increases contraction strength (frank starling law)
- Decreases stroke volume
