Chapter 2: Cardiovascular System

Section 2c: Shock

Shock occurs when the circulation cannot adequately oxygenate the body.

Causes

1. Loss of fluid either by bleeding from injury or from internal medical disorder or losses of fluid e.g. burns, prolonged vomiting and diarrhoea.
2. Heart problems such as coronary thrombosis, abnormality of the heart action, mechanical impairment of the heart action by for example barotrauma, tension pneumothorax.
3. Other factors which impair the circulation such as severe allergy, which may result from a sting from a poisonous animal, or allergy to drug or other materials.
4. Neurological - in a high spinal injury the automatic control of the blood vessels is loss. This results in a drop in blood pressure. The importance of this cause of shock is that the state of shock is accepted and not treated with intravenous fluids. Such treatment would be highly dangerous and can result in death from pulmonary oedema.

Treatment of Shock

The treatment of shock is

1. Recognise the cause, control it if possible e.g. splint fractures where possible, control external bleeding and give fluid in the following circumstances:-
   i) bleeding
   ii) burns
   iii) abnormal losses from vomiting/diarrhoea
   iv) anaphylaxis
2. Check for mechanical conditions, which can complicate the picture, e.g. tension pneumothorax. Conditions such as this should always be sought and dealt with.
3. Heart attack. Someone suffering a coronary thrombosis can have a sufficiently severe event to impair the hearts action. The usual way this is evident is that the subject complains of severe chest pain, usually described as tight or gripping. The pain can stretch from the breastbone across to both sides of the chest, can sometimes go into the neck or the jaw or left arm. It is usually accompanied with pallor, sickness and has been traditionally described and regarded as the worse pain imaginable. In this situation an ECG would give the qualified person useful information. The main treatment here is to give oxygen, reassure the subject to reduce adrenaline levels, which are highly dangerous in this situation, controls pain and obtain a defibrillator. The highest risk after a heart attack is the first four hours when cardiac abnormalities such as arrhythmias can occur and result in death. The treatment does not vary under hyperbaric conditions but defibrillation is a fire risk in the presence of an increased partial pressure of oxygen.