15 Clinical approach to shock Flashcards
Important eqns
P=FxR
BP=COxSVR or SVxHRxSVR
CO=SVxHR
Perfusion pressure = driving pressure - resisting pressure
Tissue perfusion is dependent on
perfusion pressure O2 delivery (CO and arterial O2 content)
Determinants of CO
Preload: filling pressure at end of diastole
Afterload: resists ejection of contents of the heart
Contractility: strength of muscle
Major determinants of oxygen delivery
CO
- SV
- HR
Arterial O2 content
- Hemoglobin
- Arterial oxygen saturation
Measures of perfusion
Lactate: increases during hypoperfusion during shock
ScVO2: central venous saturation of oxygen; normal consumption = 30-45%
Characteristics of shock
cellular dysfunction
damage-associated molecular patterns (DAMPs) and inflammatory mediators
multiple organ failure
death
Hypovolemic shock
Low right and left atrial pressure
Low CO
High systemic vascular pressure (from SANS activation)
Loss of plasma/blood vol, major hemorrhage, diarrhea and dehydration
Treatment of hypovolemic shock
IV fluids
Blood and blood products
Hemorrhage control
Cardiogenic shock
High R and L atrial pressure
Low CO
High SVR (poor contractility)
Cardiac tamponade, pump failure
Treatment for cardiogenic shock
Restore perfusion
Treat ischemia
Perform pericardiocentesis for cardiac tamponade
Inotropes (inc contractility)
Distributive shock
Low R and L atrial pressure
High CO
Low SVR (generalized vasodilation)
Septic shock types
Hyderdynamic: vasodilation (low SVR, high CO, variable preload)
Hypodynamic: low CO, high SVR, variable preload
Treatment of septic shock
Control source
Give antibiotics, IV, vasopressors, inotropes
Clinical manifestations
Inc HR to compensate for blood loss Dec O2 saturation Dec BP Inc RR Mottling
General treatment for shock
1 Recognize shock early
2 Assess type of shock present
3 Initiate therapy simultaneous with the evaluation into the etiology of shock
4 Restore O2 delivery
5 Identify etiologies of shock which require additional lifesaving interventions
Phases in treatment of shock
1 Salvage: obtain BP, perform lifesaving measures
2 Optimization: adequate O2 availability, optimize CO, SVO2, lactate
3 Stabilization: organ support, min complications
4 Deescalation: wean from vasoactive agents, negative fluid bal
Easy way to diagnose
Cold clammy, low CO, unable to pump -> cardiogenic shock
Warm pt, high CO, septic -> hyperdynamic shock
Pulmo artery catheter
Inserted into vein
Pulmo capillary wedge pressure = left atrial pressure
Thermodilution technique
Waveform represents CO (rate the temp travels = strength of the stream)
ECMO
Veno-venous: heart is functioning but lungs are not
Veno-arterial: heart not functioning (cardiogenic shock)
