Shock - Kaiser Flashcards
What defines shock?
1) Inadequate tissue perfusion, resulting in poor exchange of metabolic supplies and wastes.
2) A failure of oxidative metabolism involving either oxygen delivery, transport, or utilization.
How common is shock?
How dangerous is it?
Shock is the most frequent & substantial problem in critical care medicine.
Untreated, leads to multiorgan dysfunction & failure, and death.
What are the SIX types of shock, based on ETIOLOGY?
1) Septic (vasogenic)
2) Neurogenic
3) Obstructive
4) Traumatic
5) Cardiogenic
6) Hypovolemic
(“SNOTCH”)
What are the FOUR types of shock, based on HEMODYNAMIC findings?
1) Hypovolemic
2) Cardiogenic
3) Distributive
4) Obstructive
What are the two most lethal types of shock?
1) Cardiogenic (60%-90% mortality)
2) Septic (35%-40% mortality)
What are the four stages of shock?
1) Initial
2) Compensatory
3) Progressive
4) Refractory
What happens in the Initial stage of shock?
Hypoperfusion, tissue hypoxia, & lactic acidosis
What happens in the Compensatory stage of shock?
Cytokine release, hyperventilation, endogenous catecholamine release
What happens in the Progressive stage of shock?
Failing compensatory mechanisms. Worsening acidosis, capillary leakage, and organ dysfunction. Increased blood viscosity causing “sludging” of the microvasculature
What happens in the Refractory stage of shock?
IRREVERSIBLE organ damage, cell death, degradation of ATP to adenosine
What does the body do to increase blood flow to vital organs?
Why is peripheral pooling of blood sometimes seen with shock?
The body shunts blood away from the skin, acral regions, and the splanchnic system. CO/CI, RR, and tidal volume are increased. Urine production and gastrointestinal activity are reduced.
Eventually, metabolic (lactic) acidosis can lead to uncontrolled vasoconstriction and failure of precapillary sphincters. Blood ends up pooling in peripheral capillary beds and veins.
How does shock cause organ dysfunction in the:
1) Kidneys?
2) Liver?
3) GI tract?
4) Lungs?
1) Acute tubular necrosis leading to kidney failure
2) Liven congestion w/ increased enzymes & coagulopathy
3) GI ischemia & hemorrhage, peritonitis
4) ARDS (Acute Respiratory Distress Syndrome)
What defines Cardiogenic shock?
Protracted, severe malperfusion of tissues due to an ACUTE & critical reduction in heart pumping ability
How is Cardiogenic shock diagnosed?
- By clinical & hemodynamic criteria
- Exclusion of other factors: Hypovolemia, Arterial hypoxia, Vasovagal reaction
In what context is Cardiogenic shock most often seen?
How lethal is it in this context?
In patients hospitalized with an acute MI, 5-10% develop Cardiogenic shock. (Only tiny % of pts w/ unstable angina w/o MI get Cardiogenic shock.)
Accounts for 50-90% of death in these pts.
What are the clinical signs of Cardiogenic shock?
- In general: Signs of centralized circulation & organ dysfunction
- Agitation
- Pale, cool, clammy skin
- Oliguria (reduced urine production: < 20ml/hr)
- RV dysfunction (PE, RCA MI)
- Elevated venous pressure, jugular distention
- LV dysfunction (LAD/Cx MI, acute AI/MR)
- Pulmonary edema
What hemodynamic parameters indicate Cardiogenic shock?
- Systolic BP < 90mmHg, or a BP drop of > 30mmHg for > 30min
- Increased LVEPD (PAWP > 15mmHg)
- Reduced cardiac index (< 2.2 L/min/m2)
What is LVEPD? What cardiovascular parameter does it share a direct relationship with?
Left Ventricular End-Diastolic Pressure.
Related directly to PRELOAD.
What is PAWP / PCWP / PWP / PAOP?
Pulmonary Artery Wedge Pressure aka Pulmonary Capillary Wedge Pressure aka Pulmonary Wedge Pressure aka Pulmonary Artery Occlusion Pressure (Yup. They are ALL THE GODDAMNED SAME)
What is the PAWP closely related to?
(From Wiki) Due to the high compliance of the pulmonary circulation, under normal conditions the PAWP can be taken as an indirect measurement of Left atrial pressure and thus the LVEDP.
Name some myocardial etiologies of Cardiogenic shock.
1) Acute MI
2) Myocarditis
3) DCM
4) RV pump failure
5) Myocardial depression after cardiac arrest / bypass
6) Myocardial depression in septic shock
Name some mechanical etiologies of Cardiogenic shock.
1) Acute mitral insufficiency
2) Acute aortic insufficiency
3) Ventricular septum rupture
4) Ventricular free wall rupture
5) Ventricular aneurysm
5) Obstruction of LV outflow tract (aortic stenosis)
6) Obstruction of LV inflow tract (mitral stenosis)
7) Obstruction of RV outflow tract (PE)
Describe the cycle of progressive pathology in ischemic Cardiogenic shock
1) Decreased perfusion leads to
2) Cardiac injury, causing
3) Decreased stroke volume, leading to
4) Increased catecholamine release, which causes
5) Increased heart rate, which adds to the
1) Decreased perfusion
etc.
What happens to the duration of diastole during Cardiogenic shock?
Decreases due to compensatory tachycardia.
What causes the excessive myocardial oxygen consumption in Cardiogenic shock?
(Compensatory) tachycardia and increased myocardial wall tension.
What activates the sympathetic nervous system to compensate during Cardiogenic shock?
What specific effects does this activation produce?
Activation trigger: critical decrease in STROKE VOLUME
Effects:
1) Increased HR
2) Increased RR
3) Activation of RAAS
4) Baroreceptor-mediated ADH-release