Question

Define circulatory shock. Explain what hypovolemic shock is and list the ways a person may suffer from hypovolemic shock. Describe the mechanisms the body initiates in an attempt to compensate for shock, and how these mechanisms have the potential to maintain blood flow homeostasis.

Answer 1

Circulatory shock

It is a syndrome characterized by serious reduction of tissue perfusion with inadequate cardiac output.

Shock is a condition characterized by inadequate delivery of oxygen and nutrients to critical organs such as heart, brain, liver, kidney and GIT.

Signs of Shock

Pulse: Rapid, weak, thready ,Tachycardia

Respirations ■ Shallow, irregular, labored May be tachypnea (increased respirator)' rate.)

Depending upon cause the circulatory shock is divided into 4 types:

1. · Hypovolemic shock
2. · Vasogenic shock
3. · Cardiogenic shock
4. · Obstructive shock

Causes of Hypovolemic shock:

It occurs because of low blood volume resulting in decreased cardiac output.

Depending on causes this shock is divided into following types:

1. · Hemorrhagic shock: resulting in internal or external blood loss due to ruptured blood vessels.
2. · Dehydration shock: is due to dehydration
3. · Traumatic shock: trauma or injury which produce severe pain which inhibits vasomotor center in medulla oblongata.

Compensatory mechanisms in stages of circulatory shock

Non-progressive shock / First stage: it is also known as compensatory shock in which body try to compensate the loss of blood to vital organs with few mechanisms like:

Rapid compensatory mechanism - baroreceptor reflex, chemoreceptor reflex, CNS ischemic response.

Inter-mediate compensatory mechanism - renin angiotensin system, capillary fluid shift mechanism

Long term compensatory mechanism - restoration of plasma volume and proteins, restoration of red cell mass.

Progressive shock/ Second stage: here compensatory mechanisms are not able to stop progression of shock which can lead to serious damage.

Irreversible shock/ Third stage : treatment becomes ineffective and severe tissue damage to the vital organs occurs and patient dies

COMPENSATORY MECHANISMS

· Adrenergic discharge

· Hyperventilation

· Vasoactive hormones: Angiotensin . Vasopressin, Epinephrine

· Collapse

· Re-absorption of fluid from interstitial tissue

· Resorption of fluid from intracellular to extracellular space

· Renal conservation of body water & electrolyte.

Treatment of shock

General treatment:

Patient should be kept in cold because exposed to warmth can cause sweating which can lead to hypovolemia and aggravate shock.

Replacement therapy:

In hemorrhagic shock and burns whole blood or plasma or plasma substitute like dextran can be transfused.

In hypovolemic shock due to dehydration balanced electrolyte solution can be given.

Sympathomimetic drugs:

Useful in neurogenic and anaphylactic shock

dopamine , epinephrine and norepinephrine are used.

Oxygen therapy:

· For relieving hypoxia