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Although shock has been recognised for over 100 years, a clear definition of this complex event

has emerged slowly. Since 1872 many definitions of shock have been offered.

The inadequate organ perfusion and tissue oxygenation is now recognised as the definition ofshock.

The first step in the evaluation of the trauma patient is to recognise the shock condition; there are

no laboratory tests, no instrumental aids that allow this diagnosis in the first minutes.The diagnosis of shock must be based on clinical findings.All types of shock can be present in the trauma patient, and the identification of what type of

shock is taking place, is another fundamental step.

In the trauma patient the vast majority of the shock condition are hypovolemic, but also

cardiogenic or tension pneumothorax must be considered in the trauma victims.

The only conditions that does not result in shock condition are the isolated head injuries.

CATEGORY OF SHOCK

HAEMORRHAGIC SHOCK

The haemorrhagic (hypovolemic) shock is due to the acute blood loss or fluids. The amount of

blood loss after trauma is often difficult to determine. Particular attention in the clothes of thepatients or in what reported by the prehospital personnel may aid in the determination of the

blood lost.

The haemorrhage after a blunt trauma is often underestimated. A femoral not open fracture, inexample, may loose to 1 up 2 litres of blood, a pelvic fracture can loose more than two liters of

blood while a simple rib fracture can arrive up to 125 ml.

The abdominal cavity may contains large amount of blood without distension occurs; initially the

blood does not irritate the peritoneum, making the diagnosis of haemoperitoneum difficult toestablish. The diagnostic studies for the abdominal trauma are listed in chapter The trauma of

abdomen..The most rapid evaluation of the patient suspicious for shock consists of in the determination ofthe heart rate (together with the capillary refilling, pulse presence and character, patient

temperature), the blood pressure and respiratory rate. Anyway keep in consideration that in the

trauma victim the heart rate may be increased because of anxiety, and the blood pressure changewith the age (a systolic blood pressure of 85 mmHg may be normal in a child, while a systolic

blood pressure of 120 mmHg may represents hypotension in the elderly people).

CARDIOGENIC SHOCK

This type of shock is usually due to an insufficient pump function of the heart.The insufficient

pump may be due to penetrating wound of the heart, myocardial contusion, cardiac tamponade,

tension pneumothorax, diaphragmatic rupture.The evaluation of the jugular vein is a foundamental step to recognize this type of shock (jugular

vein flatted or distended).

In the old patient a myocardial infarction should be suspected following a cardiac hypoperfusion

after major trauma, but myocardial infarction may be the cause of the trauma itself. The

distended neck veins may be absent in case of severe hypovolemia. The EKG monitoring isessential to detect any dysrhytmias that can occur after trauma.

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When a cardiac tamponade exists a needle pericardiocentesis, performed by a skilled surgeon, is

mandatory.

NEUROGENIC SHOCK

In this situation there is an increased vascular system with a secondary reduction of the

circulating fluids. The neurogenic shock is due to the loss of sympathetic tone (spinal cordinjury). The classical picture of this type of shock is hypotension without tachycardia or

cutaneous vasoconstriction.

SEPTIC SHOCK

Is uncommon immediately after trauma. It may occur if the patient arrive at the emergency room

many hours after trauma. This type of shock is common for the penetrating injury, especially theabdominal injury with contamination of the peritoneal cavity by the bowel contents. Septic shock

(with multi organ failure syndrome) is a leading cause of death in the trauma patient after the

first weeks.

SIGN AND SYMPTOMS

The signs of the shock (hypovolemic shock) are usually easy to recognize when established.

These signs are indicative of low peripheral blood flow and sympatheticoadrenal activity excess.The patient in shock condition appear to be restless, anxious, and fearful. This restless may vary

to aphaty; in this situation the patient seems sleepy. After a while, if untreated or if the blood loss

is understimated, the patient will complain chilly sensation and at this time the aphaty rapidlyprogress to coma.

The most common and important signs are:

changes in blood pressure (arterial and venous blood pressure are decreased), nausea, vomiting,

tachycardia (as compensatory process marked by the amount of blood loss; but tachycardia maybe influenced by anxiety, fear so more the heart rate it is important to record every changes in the

heart rate), vasoconstriction (in this case is an effort to compensate the reduced cardiac output. Inhaemorragic shock the heart may receive 25% of the total cardiac output versus the normal 5-8%).

These vascular responses depend on the activation of the sympathetic and adrenal medullar

systems.Other signs include pale and cold skin, tachypnea and all the bloods changes as hemodiluition,

hormonal changes, pH changes, renal dysfuction ecc.

MANAGEMENT OF THE SHOCK

The primary goal of shock resuscitation is to restore adequate tissue oxygen delivery and to treat

the underlying pathology to prevent recrudescence of the shock state or the death of the patient.

Hypotension, tachycardia, hypothermia, pallor, cool extremities, cyanosis, decreased capillaryrefill, diaphoresis and oliguria are physiologic signs suggestive of hypovolemic shock.

Treatment of the blood pressure, heart rate, and other clinical signs and symptoms of

hypoperfusion is directed toward restoration of cellular perfusion.

Since the primary defect during shock is hypovolemia, volume infusion must be the primarytherapy. Adequate volume loading is initiated after adequate vascular access is obtained, which

usually requires the insertion of at least two large bore venous catheter (14 - 16 G). Catheter may

be inserted percutaneously in an arm vein or/ and in the femoral vein.

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