**5. Classification of different categories of shock**

	- **a.** Septic shock
	- **b.** Cardiogenic shock
	- **c.** Obstructive shock (tension pneumothorax, pericardial tamponade)
	- **d.** Neurogenic shock
	- **e.** Anaphylactic shock

Sometimes there is a combination or coexistence of more than one type of shock [2].

### **5.1. Hemorrhagic shock (hypovolemia)**

There is loss in intravascular volume which decreases preload and diminishes the cardiac output. Sometimes despite fluid or blood replacement, inotropes and vasopressors might need to be added on [1].

In hemorrhagic shock, due to rapid drop in the blood volume, there is activation of the baroreceptors causing peripheral vasoconstriction and increased cardiac contractility and heart rate. Initially, as a response to the blood loss, the body tries to compensate by increasing the pulse rate and diastolic pressure, causing the pulse pressure (difference between systolic and diastolic pressure) to narrow. As the volume deficit continues, the cardiac output drops followed by reduction in the blood pressure. Simultaneously there is renal vasoconstriction too, leading to tubular necrosis. There is impaired fuel delivery to all the vital organs including the brain, due to impaired hepatic glucose output and peripheral lipolysis. The most common cause of hemorrhage is trauma [2].

*5.2.1. Stages of hemorrhagic shock*

parameters,

urgent attention,

See **Figure 3**.

**5.3. Effects of hemorrhage**

• Site and severity of injury.

• Comorbidities and medications.

**Figure 3.** Stages of hemorrhagic shock [2].

• Time lapse (from injury to resuscitation).

• Extremes of age.

**Stage 1:** Loss of approximately 750ml of blood, with no significant change in physiological

Shock

31

http://dx.doi.org/10.5772/intechopen.76242

**Stage 3:** loss of 1500ml- 2000ml of blood, affecting the normal body physiology, requiring

**Stage 4:** loss of >2000ml of blood resulting in severe disturbance of body functions, calling for

There are some factors that can alter the outcome in patients with shock. Factors like:

**Stage 2:** loss of 750-1500ml of blood, with mild changes in the vital signs,

urgent replacement of blood to restore normal functions.

#### **5.2. Management of hemorrhagic shock.**

The main treatment is to stop bleeding and restore volume by administering fluids, including blood.


Patient may need to have orogastric tube in place to relieve gastric distension and urinary catheter to monitor output. Patient may need central venous access for measuring central venous pressure, fluid resuscitation, and blood sampling. Imaging studies would aid to the diagnosis of the source of hemorrhage. Initial resuscitation should start with 1–2 L of fluid bolus in adults and 20 ml/kg in pediatric patients. Blood transfusion might be needed too. Balanced resuscitation must be the target in hemorrhagic shock management, which means balancing organ perfusion with risks of rebleeding and accepting lower than normal blood pressure [2].

Target goal of resuscitation is to maintain a urinary output of 0.5 ml/kg/hr. in adults and 1 ml/ kg/hr. in pediatric patients [2].

In severe bleeding, uncross-matched blood can be used. Consider O negative blood in women of childbearing age. Vasopressors would usually worsen the hypoperfusion, so it must be considered only if resuscitation by fluids and blood fails. Bedside ultrasound scanning (E-FAST) can help in detecting hemorrhage in intra-abdominal, pleural, pericardial, and pelvic cavities. Knowing the base deficit is important as it can help to distinguish trivial bleeding from significant blood loss. Base deficit is the amount of base needed to be added in 1 L of blood to normalize the pH. Normal base deficit is more positive than −2 mEq/L. It can become negative early in hemorrhage when the pH and blood pressure remain normal [2].

During hemorrhage, tissues suffer academia and accumulation of lactic acid which can be treated if resuscitated promptly and adequately. Treatment is with fluids, blood, and control of hemorrhage [2].

#### *5.2.1. Stages of hemorrhagic shock*

**Stage 1:** Loss of approximately 750ml of blood, with no significant change in physiological parameters,

**Stage 2:** loss of 750-1500ml of blood, with mild changes in the vital signs,

**Stage 3:** loss of 1500ml- 2000ml of blood, affecting the normal body physiology, requiring urgent attention,

**Stage 4:** loss of >2000ml of blood resulting in severe disturbance of body functions, calling for urgent replacement of blood to restore normal functions.

See **Figure 3**.

rate. Initially, as a response to the blood loss, the body tries to compensate by increasing the pulse rate and diastolic pressure, causing the pulse pressure (difference between systolic and diastolic pressure) to narrow. As the volume deficit continues, the cardiac output drops followed by reduction in the blood pressure. Simultaneously there is renal vasoconstriction too, leading to tubular necrosis. There is impaired fuel delivery to all the vital organs including the brain, due to impaired hepatic glucose output and peripheral lipolysis. The most common

The main treatment is to stop bleeding and restore volume by administering fluids, including

• Determine the level of conscious (by evaluating the eye, verbal, and best motor response)

• Expose the patient from head to toe to look for injuries or deformities, bearing in mind to

Patient may need to have orogastric tube in place to relieve gastric distension and urinary catheter to monitor output. Patient may need central venous access for measuring central venous pressure, fluid resuscitation, and blood sampling. Imaging studies would aid to the diagnosis of the source of hemorrhage. Initial resuscitation should start with 1–2 L of fluid bolus in adults and 20 ml/kg in pediatric patients. Blood transfusion might be needed too. Balanced resuscitation must be the target in hemorrhagic shock management, which means balancing organ perfusion with risks of rebleeding and accepting lower than normal blood

Target goal of resuscitation is to maintain a urinary output of 0.5 ml/kg/hr. in adults and 1 ml/

In severe bleeding, uncross-matched blood can be used. Consider O negative blood in women of childbearing age. Vasopressors would usually worsen the hypoperfusion, so it must be considered only if resuscitation by fluids and blood fails. Bedside ultrasound scanning (E-FAST) can help in detecting hemorrhage in intra-abdominal, pleural, pericardial, and pelvic cavities. Knowing the base deficit is important as it can help to distinguish trivial bleeding from significant blood loss. Base deficit is the amount of base needed to be added in 1 L of blood to normalize the pH. Normal base deficit is more positive than −2 mEq/L. It can become negative

During hemorrhage, tissues suffer academia and accumulation of lactic acid which can be treated if resuscitated promptly and adequately. Treatment is with fluids, blood, and control

early in hemorrhage when the pH and blood pressure remain normal [2].

cause of hemorrhage is trauma [2].

30 Essentials of Accident and Emergency Medicine

(Glasgow Coma score, GCS).

avoid hypothermia.

kg/hr. in pediatric patients [2].

pressure [2].

of hemorrhage [2].

blood.

**5.2. Management of hemorrhagic shock.**

• Establish a secure patent airway and optimize breathing.

• Establish intravenous access for fluid resuscitation.

#### **5.3. Effects of hemorrhage**

There are some factors that can alter the outcome in patients with shock. Factors like:



**Figure 3.** Stages of hemorrhagic shock [2].

Hemostasis and balanced fluid therapy (including blood) should be started as soon as signs of hemorrhage are suspected [2].

As mentioned in the table above, patients in classes I and II have good compensatory mechanism to overcome the blood loss and may just need crystalloid infusion, while patients in classes III and IV have lost significant amount of blood and need to have blood transfusion [2].

Soft tissue injuries and fractures compromise the hemodynamics of patients with trauma, e.g., 1500 ml blood can be lost in femur fractures [2].

The cytokines released during tissue injury increase permeability of tissues. Fluid shifts and volume depletion in the intravascular compartment cause hypovolemia [2].
