Hypovolemic Shock

Surgery

Shock

Hypovolemic Shock

• Most common type in surgical practice.

• Reduction in intravascular volume.

  • Blood loss: Trauma, GI bleeding, ruptured aneurysm
  • Plasma loss: Burn
  • Water & electrolytes loss: Diarrhoea, vomiting

• Easily correctable.

Classes of haemorrhagic shock Based on estimated blood loss & patients’ initial presentation (ATLS)

Class	Blood loss (ml)	Blood loss - % volume	Pulse / min	Systolic BP	Pulse pressure	Respiration rate	Urine (ml/hr.)	Mental status	Initial fluid
Class I	Up to 750	Up to 15%	<100	Normal	Normal/increased	14-20	>30	Slightly anxious	Crystalloid
Class II	750-1500	15-30%	100-120	Normal	Decreased	20-30	0.5 to 1.5 cc/kg/hour	Mildly anxious	Crystalloid
Class III	1500-2000	30-40%	120-140	Decreased	Decreased	30-40	20-30	Anxious, confused	Crystalloid & blood
Class IV	>2000	>40%	>140	Decreased	Decreased	>35	5-15 Negligible	Confused, lethargic	Crystalloid & blood

Signs and symptoms

• Anxiety, restlessness, altered mental state
• Distracted look in the eyes
• Thirst and dry mouth
• Cool, pale, clammy skin
• Hypothermia
• Rapid and shallow respirations
• Oliguria (Urine Output<30ml/hour)
• Hypotension
• A rapid, weak, thready pulse

Treatment:

Resuscitation

• a. To ensure clear airway, adequate breathing and circulation.
• b. Provision of 100 percent oxygen by a face mask. Deliver oxygen at a flow of 5-6 liters per minute

Hypovolemic shock

• Position: The patient is kept in “head down position”.

• Arrest external bleeding

• Fluid resuscitation- Two wide bore (14-16 gauge) peripheral venous access.

• PRBCs: Life threatening/ continued bleeding. Vasopressor & inotropes- little role

• Invasive monitoring: CVP, PAWP, acid-base status, UOP

• Fluid replacement—Crystalloid solution like Ringer lactate is ideal in situations where Na and H2O loss is predominant and will also serve as initial treatment in hemorrhagic shock.

• Blood transfusion is advised in hemorrhagic shock and

• Plasma transfusion in case of burns.

• Colloids, e.g. Gelatin (Hemaccele), Hydroxyethyl starch (HES) and Dextran remain longer in the circulation and draw extracellular fluid (ECF) into the circulation by osmotic pressure.

Trauma

• Shock- secondary to hemorrhage in most trauma patients
• Patient can be in shock before developing hypotension
• Hypotension- a sign of decompensation (class III )

5 locations for major blood loss: - Chest - Abdomen - Pelvis and retroperitoneum - Multiple long bone fractures ( lower limb) - External hemorrhage

Pathophysiology of blood loss

Compensatory responses occur as: - Progressive vasoconstriction- skin pallor - Tachycardia to preserve cardiac output. - Increased peripheral resistance- catecholamines.

• Venous return- preserved in early stage, reduced later due to reduced blood volume in venous system.
• If Continued bleeding- shock develops.
• Inadequate tissue perfusion, metabolic acidosis.

Classes of hemorrhagic shock

Class	Blood loss (ml)	Pulse	BP
Class I	Up to 750	<100	Normal
Class II	750- 1500	>100	Normal
Class III	1500- 2000	>120	Decreased
Class IV	> 2000	>140	Decreased

Circulation Indicators of shock in trauma patients

• Tachycardia
• Agitation
• Tachypnea
• Sweating
• Cool extremities
• Weak peripheral pulse
• Decreased pulse pressure
• Hypotension
• Oliguria