1. Shock (overview) Flashcards
Although blood pressure (hypotension) is generally thought of when discussing shock, shock is actually a
CELLULAR DISEASE due to either inadequate perfusion (the O2 demand is greater than the oxygen delivered) or the inability of cells to utilize the delivered oxygen (issues with oxygen utilization/consumption).
Refer to figure 5-1 to study the pathophysiology of shock
Inadequate tissue perfusion OR impaired O2 uptake
There are 3 stages of all types of shock:
- Compensatory
- Progressive
- Refractory
The rapidity with which a pt progresses thru these shock stages ___
varies depending upon many factors.
During the COMPENSATORY STAGE of shock (figures 5-2 and 5-3), the blood pressure (bp)
is maintained as a result of 2 mechanisms: stimulation of the sympathetic nervous system and activation of the renin-angiotensin-aldosterone system (RAAS).
Sympathetic Nervous System Stimulation
figure 5-2 (physiology of compensatory stage of shock)
Decrease in cardiac output/circulating volume or increased oxygen utilization
I
V
sympathetic stimulation
I
V
(HR) Vasoconstriction (contractility)
I I I
I V I
I——> BP maintained <—————-I
Renin-Angiotensin-Aldosterone System (RAAS) Activation
Figure (5-3) Compensatory stage of shock due to RAAS
Decrease in CO/circulating volume or increased o2 utilization leads to RAAS ACTIVATION which
leads to
a) Renin secretion –>Angiotensin I–>Angiotensin II ———->Vasoconstriction—->BP maintained
b)Aldosterone release–>Na+ and H20 retention–>BP maintained
Clinical Signs/Symptoms of the Compensatory Stage of Shock (BP maintained)
-tachycardia
-tachypnea, respiratory alkalosis
-Normal PaO2
-Oliguria
-Skin is pale, cool (except in early sepsis)
-Restlessness, anxiety
-Complaints of thirst
-Remember, BP IS MAINTAINED
Clinical Signs/Symptoms of the PROGRESSIVE Stage of Shock (Compensatory mechanisms failing)
-HYPOTENSION
-Worsening tachycardia, tachypnea, oliguria
-metabolic acidosis
-decreased PaO2
-clammy, mottled skin
-further change in LOC
-the pt may complain of nausea
Clinical Signs/Symptoms of the REFRACTORY Stage of Shock
-pt not responsive to interventions
-Severe systemic hypoperfusion, MULTIPLE ORGAN DYSFUNCTION SYNDROME (MODS)
-The pt may survive shock, but die from failure of one or more organs
-Pulmonary (ARDS)
-Kidney (acute tubular necrosis)
- Heart (failure, ischemia)
-Hematologic (disseminated intravascular
coagulation)
- Neurological (encephalopathy, stroke)
- Liver (failure)
Types of Shock:
-Hypovolemic
-Septic
-Anaphylactic
-Neurogenic (seldom tested)
-Cardiogenic (covered in CV)
-Obstructed (covered in CV and Resp chapters)
-Tension pneumothorax
-Massive pulmonary embolism
-Cardiac tamponade