management of shock in an injured patient.

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Shock

The initial step in managing the shock in an injured patient is to recognize its presence. The initial diagnosis is based on clinical appreciation of the presence of inadequate tissue oxygenation & organ perfusion. It is also defined as a situation when the circulation is inadequate for metabolic needs.

Principles of Shock Recognition and Management:
 Patients in shock may only exhibit subtle signs
 Identifying the cause is usually less important than starting treatment
 Goal is to restore perfusion and correct the shock state
 Frequent reassessment of response to treatment is important

Sole reliance on systolic blood pressure as an indicator of shock results in delayed recognition of shock. The Body's Mechanisms try to compensate for Shock until up to 30% of the patient’s blood volume is lost by increase cardiac output (tachycardia), increase oxygen supply (tachypnea) and release of vasoactive mediators which cause nausea and peripheral vasoconstriction (Cool, clammy skin, increased diastolic pressure, decreased urine output).

Types of Shock:
Shock in an injured patient may be classified as haemorrhagic or non-haemorrhagic. Recognition of the type of shock depends on history taking, clinical examination and selected additional tests; however, this should not delay aggressive volume resuscitation.

1/ Hemorrhagic Shock:
Definition: Acute loss of circulating blood; can be internal and / or external. It is the most common in trauma patients. Virtually all patients with multiple injuries have an element of hypovolaemia. Additionally, most other types of non-haemorrhagic shock respond partially or briefly to volume resuscitation. Therefore, treatment is usually instituted as if the patient is hypovolemic (always treat for hemorrhagic shock first). The small number of patients whose shock has aetiology can be identified and managed.

The Four Stages of Hemorrhagic shock:

 Stage 1 haemorrhage - 0 to 15% of total blood volume (TBV)
 Stage 2 haemorrhage - 15 to 30% of TBV
 Stage 3 haemorrhage - 30 to 40% of TBV
 Stage 4 haemorrhage - > 40% of TBV

2/ Non-hemorrhagic Shock:
 Hypovolemic (non-hemorrhagic) shock
 Due to vomiting , diarrhoea, "third spacing" of fluid
 Treat with IV Lactated Ringers or saline
 Does not need blood transfusion
 Anaphylactic shock
 Due to allergic reaction with release of vasoactive mediators which can cause airway oedema & vasodilatation
 Treat with IV fluids & epinephrine
 Septic Shock
 Can be a late or delayed complication
 Patient may have fever or hypothermia
 Treat with IV fluids ; sometimes need secondary treatment with vasopressors
 Finding and directly treating the source of the sepsis is critical to save the patient (start antibiotics, drain abscess if present, etc.)
 "Obstructive" : key sign is distended neck veins in the patient with shock
 Tension pneumothorax
 Treat with anterior needle thoracostomy
 Cardiac tamponade
 Treat initially with IV fluids
 Consider pericardiocentesis
 Pulmonary embolus :
 Need to confirm diagnosis (V/Q or CAT scan)
 Then treat with thrombolytics or embolectomy
 Cardiogenic : due to heart pumping dysfunction
 Acute myocardial infarction (sometimes this can be the original cause of a person injuring themselves in a traffic accident or fall)
 Myocardial contusion
 Actually is rare even with major blunt chest trauma
 May require treatment with vasopressors (dopamine)
 Neurogenic : due to spinal cord injury and loss of sympathetic nervous system outflow
 Results in venous pooling, peripheral vasodilatation
 Often has relative bradycardia
 Treat with IV fluids first, then alpha vasoconstrictors if hypovolemic shock ruled out
 Spinal shock : actually is a "cord-stunning" syndrome
 Flaccidity and loss of reflexes
 Is an "electrical" phenomenon of the spinal cord
 May have complete recovery

General Symptoms of Shock
General Signs of Shock

 Weakness
 Dizziness
 Light-headedness
 Nausea
 Sense of impending doom  Decreased mental status or confusion
 Cool, clammy, or grey ashen colour skin
 Diaphoresis
 Tachycardia
 Tachypnea
 Hypotension
 Oliguria








Rapid Fluid Resuscitation for Shock:
 Place two large bore canulas (> 18 gauge).
 Draw blood for type and cross-match from the needle stick for the IV line
 Initially run fluid in "wide-open"
 Use large drip chamber IV tubing
 May need pressure bags on the IV bags
 Usually use Lactated Ringers
 Choose normal saline if patient may be hyperkalemic
 Normal saline also preferred for same IV line to be used for blood transfusion
 Do not use vasopressors ; treat with fluids

Other Resuscitative procedures for Severe Shock
 Blood transfusion
 Type - O-negative (if needed immediately)
 Type - specific (if needed in < 15 minutes)
 Fully cross-matched
 Emergent left thoracotomy, pericardiotomy, aortic clamping
 Auto transfusion
 Most useful for blood output from chest tubes

Indications for Emergent Transfusion with O-Negative Blood

 No palpable blood pressure at arrival
 Multiple simultaneous patients requiring emergent transfusion
 Rapid deterioration or sudden large volume external blood loss and type specific blood not immediately available