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Acute Nursing (Nurs 3000) Stages Of Shock - Lecture Notes 6

John Marsh
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Stages of Shock – Lecture notes 6

Trent University

Acute Nursing (Nurs 3000)

Stages of Shock
1. Compensatory
2. Progressive
3. Refractory (irreversible)
Compensatory Stage (body’s initial response)
 This continuum begins with the initial stage of shock that occurs at a cellular level and is
usually not clinically apparent. Metabolism changes at the cellular level from aerobic to
anaerobic, causing lactic acid buildup. Lactic acid is a waste product and must be
removed by the liver. However, this process requires oxygen, which is unavailable
because of the decrease in tissue perfusion.
 In the compensatory stage, the body activates neural, hormonal, and biochemical
compensatory mechanisms in an attempt to overcome the increasing consequences of
anaerobic metabolism and to maintain homeostasis
One of the first clinical signs of shock may be a fall in blood pressure (BP), which occurs
because of a decrease in CO and a narrowing of the pulse pressure
The myocardium responds to the SNS stimulation and the increase in oxygen demand by
increasing the heart rate and contractility (Bench, 2004). However, increased contractility
increases myocardial oxygen consumption (MVO2). The coronary arteries dilate in an attempt to
meet the increased oxygen demands of the myocardium.
The baroreceptors in the carotid and aortic bodies immediately respond by activating the SNS.
The SNS stimulates vasoconstriction and the release of the potent vasoconstrictors epinephrine
and norepinephrine
Blood flow to the most essential (vital) organs, the heart and the brain, is maintained
while blood flow to the nonvital organs, such as the kidneys, the GI tract, the skin, and the
lungs, is diverted or shunted
Decreased blood flow to the kidneys activates the renin–angiotensin system (RAAS)
 vasoconstrictor that causes both arterial and venous vasoconstriction.
The net result is an increase in venous return to the heart and an increase in BP
Angiotensin II also stimulates the adrenal cortex to release aldosterone, which results in
sodium and water reabsorption, and potassium excretion by the kidneys.



Acute Nursing (Nurs 3000) Stages Of Shock - Lecture Notes 6

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