Lec 30 Shock Flashcards
What is definition of shock?
inadequate organ perfusion to meet tissue’s oxygenation demand
What is the definition of hypotension?
transient fall in BP
- systolic BP < 90 OR mean arterial P < 60 OR decrease in systolic BP > 40 mmHg from pts baseline
What is pathophysiology of shock?
ATP + H2O –> ADP + Pi + H
- lack of ATP production –> Na/K failure
anaerobic metabolism –> accumulation of acid –> metabolic acidosis - cell swelling leading to rupture + death
Why do we monitor pt undergoing shock?
- to understand their disease
- to describe pts physiologic status
- facilitate diagnosis and treatment of shock
b/c shock cna change rapidly
When do you use pulm artery catheter with shock?
- to get index of volume status [normal central venous pressure = normal volume] and cardiac status [calculate CO/CI]
How can you use ultrasound to measure volume status?
if SVC not collapsed means there is sufficient volume status
Why might you not do swan gans catheter on ever pt who comes in with shock?
can cause trauma/complications
What does SVI tell you?
stroke volume index = stroke volume / body mass
What does LV stroke work index tell you?
measure of cardiac contractility
What is equation for systemic vascular resistance index?
SVRI = [MAP- CVP] / CI * 80
increases with vasoconstriction, decreases with vasodilation
What is equation for pulmonary vascular resistance index?
PVRI = [MPAP - PWAP] / CI * 80
increases with constriction, PE, hypoxia
Lung circuit resistance affects which part of heart function? what about systemic circuit resistance?
pulm circuit resistance affects RV function
systemic circuit resistance affects LV function
What is equation for vascular resistance?
vascular resistance = change in pressure / blood flow
What is definition of O2 delivery?
volume of gaseous O2 delivered to LV per min
What is the definition of O2 consumption?
volume of gaseous O2 which is actually used by the tissue per min
What is definition of O2 demand?
volume of O2 actually needed by tissues to function in an aerobic manner
What happens if O2 demand > consumption?
anaerobic metabolism
What are 3 signs of organ hypo-perfusion?
- mental status changes = obtunded b/c lack of perfusion to brain
- oliguria = lack of kidney perfusion
- lactic acidosis
What are the 4 categories of shock?
- hypovolemic
- cardiogenic
- distributive
- obstructive
What are the goals of shock resuscitation?
restore BP
normalize systemic perfusion
preserve organ function
What are some causes of hypovolemic shock?
- hemorrhage
- vomiting
- diarrhea
- dehydration
- burns
What is hypovolemic shock? What happens to CO/SVR/venous return/PAWP?
step1
- shock related to loss of fluid
signs:
- decrease CO, decrease venous return, increase SVR
- decrease PAWP [indicates reduced diastolic filling pressure]
What is the first sign of shock?
step1
tachycardia