Tag: human circulatory system

In the acronym DR ABC, C stands for circulation. Signs of circulation compromise to watch out for include bleeding or shock symptoms.

The Human Circulatory System

The human circulatory system comprises of the heart, the blood vessels, and the blood. All these components need to be working efficiently so that every tissue within the body is supplied with oxygenated blood.

Shock Causes

A decrease in blood pressure and SPO² indicate circulatory failure – the brain is slowly dying due to lack of oxygen, and so, it triggers a defense mechanism: SHOCK.

Any issue affecting the heart, the blood vessels, or the blood volume, may lead to a decrease in the body’s blood circulation, leading to a reduction in blood pressure and volume, which in return cause a decrease in tissue perfusion.

Decreased Cardiac Output = Decreased Circulating Volume & Pressure = Reduced Venous Return

Types of shock include:

1. cardiogenic shock
2. obstructive shock
3. neurogenic shock
4. septic shock
5. anaphylactic shock
6. hypovolaemic shock

Causes of shock can be divided into 3 categories:

1. Decrease in the Pumping Action of the Heart

A drop in cardiac output can result in a:

1. Cardiogenic Shock – this may happen due to a heart defect or disorder (cardiogenic = issue originating from the heart itself) eg. Congestive Heart Failure (CHF) or Ischaemic Heart Disease (IHD);
2. Obstructive Shock – this may happen due to cardiac compression in cases such as in cardiac tamponade (bleeding within the pericardial space) and tension pneumothorax (air accumulation in the pleural space which compresses the lungs and decreases venous return to the heart).

2. Blood Vessel Dilation

Following vasodilation, which refers to the dilation of the blood vessels, a casualty can suffer a distributive shock:

1. Neurogenic Shock – happens following a spinal injury, head injury, or opiate overdose;
2. Septic Shock – happens following a severe infection which causes the casualty’s blood pressure to drop to a dangerously low level;
3. Anaphylactic Shock – happens following a severe allergic reaction

NOTE: due to a biochemical process in the body, chemicals released cause vasodilation, which then causes either a septic shock or an anaphylactic shock.

3. Blood or Fluid Loss

Severe bleeding or severe dehydration can lead to a hypovolaemic shock. This happens due to the drop in blood volume.

Progressive Shock Clinical Indicators

• initial weak rapid pulse that eventually becomes thready or absent (body increases heart rate to compensate due to lack of blood; eventually, drop in cardiac output = drop in stroke volume = weak heartbeat)
• initial rapid irregular breathing that eventually becomes laboured and dyspnoeic
• initial pale skin that eventually becomes cold, clammy and mottled (happens since the body compensates lack of oxygen circulation by sending it in the most important areas rather than in the extremities)
• cyanosis – signifies established hypoxia
• weakness and fatigue – signifies cerebral hypoxia (lack of oxygen in the brain)
• confusion and disorientation
• altered level of response leading to unresponsiveness…casualty is now at risk of cardiac arrest!

Shock First Aid

1. identify cause of shock
2. control cause of shock
3. assist casualty in shock position – elevate legs by about 30cm to increase venous return; if casualty is conscious but dyspnoeic, a semi-sitting position helps provide better breathing
4. maintain casualty’s body temperature – this helps in avoiding hypothermia, which would disrupt an open wound’s clotting process, leading to longer bleeding time
5. administer high-concentrated oxygen if available
6. increase ventilation by opening windows if inside
7. call 112 for assistance
8. monitor casualty for deterioration – if casualty is in recovery position, attempt to maintain shock position i.e. elevated legs, if possible
9. provide reassurance at all times

NOTE: The term vasoconstriction refers to constriction of the blood vessels. It can be clinically indicated in blood pressure results that show a difference of about 20 only between the systolic and diastolic readings. In such case, the pulse is weak or not palpable.

Bleeding

Bleeding amount depends on what it is originating from:

• ARTERIES – spurting blood, pulsating flow, bright red colour
• VEINS – steady, slow blood flow, dark red colour
• CAPILLARIES – slow and even flow

Bleeding severity depends on the injury body site, blood loss volume, time frame of blood loss volume, casualty’s age (worse in children and the elderly), and casualty’s health status prior to the injury.

Catastrophic bleeding refers to bleeding in which 30% of blood volume is lost. Such bleeding takes priority over Airway and Circulation in the DR ABC acronym.

The major consequence of blood loss is a hypovolaemic shock (explained further up). During this type of shock, the heart becomes unable to pump enough blood throughout the body due to severe blood or fluid loss. This leads to organs shutting down.

External Bleeding First Aid

1. wear gloves to protect self
2. control bleeding through direct pressure or using a pressure dressing
3. monitor and provide first aid for shock

Notes:

• In bleeding circumstances without signs of shock, elevation is not recommended anymore.
• Indirect pressure (pressing on arteries eg. on femoral or brachial artery) is not a recommended bleeding control technique anymore.
• If direct pressure method fails, you may use an emergency bandage, tourniquet, or haemostatic agents, all of which require prior specific training.
• In catastrophic bleeding first aid, one may pack the wound with a towel. Worrying about an infection is not a primary concern at this point, since catastrophic bleeding may lead to loss of life.
• Haemostatic Agents can be poured on wounds to stop catastrophic bleeding. Only materials specifically prepared for bleeding purposes may be used
• A tourniquet is a device that helps apply pressure to a limb or extremity to limit the flow of blood. It may be used in emergency situations, during surgery, or in the post-operative rehabilitation period.
• Normal use tourniquets are orange in colour, while the Combat Application Tourniquet (CAT) is usually black.

Internal Bleeding

Internal bleeding may be caused as a disease process eg. due to a stomach ulcer, or trauma.

Common sites of serious internal bleeding include the head, the chest, the abdomen and pelvis.

Internal bleeding is more difficult to diagnose, since it usually doesn’t show. The worst type of internal bleeding happens in the pelvic area, right in the retroperitoneum.

Recognition of internal bleeding may be done through:

1. History
2. Signs & Symptoms
3. Pain & Tenderness
4. Revealed Internal Bleeding (eg. internal bleeding in the head may produce trickling blood out of orifices such as from the ear)

Types of Internal Bleeding:

• Otorrhoea – blood coming out of the ear
• Rhinorrhoea – blood coming out of the nose
• Haemoptysis – coughed out blood
• Haematemesis – vomited blood
• Haematuria – bleeding in the urine
• Rectal Bleeding – bleeding coming out of the intestines
• Bruising

NOTE: If there is suspicion of internal bleeding, it NEEDS TO BE ASSUMED! Monitor for ABC compromise and signs of shock, and provide first aid as needed!

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