Shock
·
Shock
is a syndrome characterized by decreased tissue perfusion and impaired cellular
metabolism.
·
This
results in an imbalance between the supply of and demand for oxygen and
nutrients to support the vital organs and cellular functions
Stages of shock
1.
Initial
stage
2.
Non
Progressive/Compensatory stage
3.
Progressive/
Intermediate stage
4.
Irreversible/
Refractory stage
1. Initial
phase:
·
↓in
mean arterial pressure (Mean arterial pressure is calculated by the formula-
MAP= (systolic blood pressure +2diastolic pressure )/3
·
Compensatory
mechanism effective in this stage.
·
Decreased
cellular metabolism
·
Overall
cellular metabolism is aerobic
·
The
only objective sign of this stage is - tachycardia
2. Non
progressive/ Compensatory Stage
Results
from stimulation of the sympathetic nervous system and subsequent release of
catecholamine's
The
body shunts blood from organs such as the skin, kidneys, and gastrointestinal
tract to the brain and heart to ensure adequate blood supply to these vital
organs.
Overall
Pathophysiology:-
Decrease in MAP (10-15 mmHg From
baseline)
↓
Kidney and chemical compensatory
mechanism activate
↓
Kidney and baroreceptor sense an
ongoing decrease in MAP & activates RAAS, NE, epinephrine release
↓
Tissue hypoxia in Non-vital
organs i.e. GI
↓
Some metabolism is anaerobic
↓
Acid - Base and electrolytes
balance change
↓
Acidosis and ↑ in K ion in blood
(hyperkalaemia )
Neuronal
compensation:
Decreased BP
↓
Detection of decreased BP by
baroreceptor and chemotherapy and impulses
are relayed to VMC in MO
↓
Sympathetic stimulation (ANS)
↓
Release of epinephrine and
nor-epinephrine from adrenal cored
Endocrine
Compensation
Decreased BP
↓
Stimulation of anterior and
posterior pituitary → release ADH → retention of water and salt
↓
Release GIucocorticoid and
mineralocorticoid
↓
Increase blood GIucose
↓
Na and water retention
↓
Stimulation of renin angiotensin
↓
Causes vasoconstriction
↓
Increased BP
Chemical Compensation
Decreased cardiac output
↓
Decreased pulmonary blood blow
↓
Ventilation perfusion imbalance
↓
Stimulation of chemoreceptors for O2
concentration
↓
Increased rate and depth of
respiration
Clinical features:
Finding
|
Compensatory features
|
Blood
pressure
|
Normal
|
Heart
rate
|
> 100 bpm
|
Respiratory
status
|
>
20 breaths/min
|
Skin
|
Cold, clammy
|
Urinary
output
|
Decreased
|
Mentation
|
Confusion
|
Acid-
base balance
|
Respiratory
alkalosis
|
Medical Management
Identify
the cause of the shock and correct the underlying disorder so that shock does
not Progress.
Fluid
replacement and medication therapy must be initiated to maintain an adequate
blood pressure and re-establish and maintain adequate tissue perfusion.
3. Progressive
stage:-
In
the progressive stage of shock, the mechanisms that regulate blood pressure can
no longer compensate and the MAP falls below normal limits, with an average
systolic blood pressure of less than 90 mm Hg.
Pathophysiology
Sustained ↓ in MAP ( > 20 mmHg)
Compensation
functioning but unable to deliver sufficient oxygen to even vital organs that
produces ischemia.
Biochemical
mediators cause myocardial depression
Life
threatening emergency
Very
sensitive tissues start to die
Clinical features
Findings
|
Progressive
|
Blood
pressure
|
Systolic
< 80-90 mm Hg
|
Heart
rate
|
> 150 beats per
minute
|
Respiratory
status
|
Rapid,
shallow respirations; crackles
|
Skin
|
Mottled, petechiae
|
Urinary
output
|
0.5
ml/kg/hour
|
Mentation
|
Lethargy
|
Acid-base
balance
|
Metabolic
acidosis
|
Medical Management
Appropriate
intravenous fluids and medications to restore tissue perfusion by:
·
Optimizing
intravascular volume,
·
Supporting
the pumping action of the heart,
·
Improving
the competence of the vascular system.
4. Irreversible/
Refractory stage
·
Patient
does not respond to treatment
·
Blood
pressure remains low.
·
Renal
and liver failure and vital organs continues to deteriorate in function.
Too
little O2 reaching to tissue→ too much
cell death → tissue damage→ overwhelming changes in vital organ→ irreversible
changes in tissues→ cell deterioration and → cellular death
Medical Management
Medical
management during the irreversible stage of shock is usually the same as for
the progressive stage.
Nursing Management
·
Carrying
out prescribed treatments, monitoring the patient
·
Preventing
complications
·
Protecting
the patient from injury
·
Providing
comfort.
COMMENTS