CHAPTER 4 Shock and trauma
Shock
Shock is defined as an abnormality of the circulation that causes inadequate organ perfusion and oxygenation. Five types of shock may be encountered in surgical practice: hypovolaemic, septic, cardiogenic, neurogenic and anaphylactic.
Hypovolaemic shock
Classification
The blood volume of a 70 kg man is approximately 5 L or 80 mL/kg. Hypovolaemic shock can be divided into four categories, depending on the amount lost:
Symptoms and signs
The symptoms and signs relate to the amount of blood lost:
Treatment
Shock is a surgical emergency and needs rapid treatment.
Septic shock
Septic shock is part of the systemic inflammatory response syndrome (SIRS). Sepsis is defined as SIRS with a confirmed source of infection. Septic shock is defined as hypotension and hypoperfusion despite adequate fluid resuscitation. Septic shock is uncommon in trauma unless there has been a delay in presentation.
Causes
Septic shock is due to the release of a number of pro-inflammatory mediators such as IL-1, IL-6, TNF-α, PAF and the eicosanoids; and as a result of bacterial endotoxins (lipopolysaccharides). Septic shock is usually due to Gram-negative organisms such as E. coli, Klebsiella and pseudomonas, although peptidoglycans and teichoic acids in Gram-positive bacteria can also have similar effects. The pathophysiology underlying shock in septic patients includes:
Symptoms and signs
There may be an obvious source of infection, together with a predisposing condition. The patient may be confused and restless; initially the skin is hot and flushed and the pulse characteristically ‘bounding’. Vasoconstriction and the classic signs of shock may develop later.
Treatment
This is urgent and involves resuscitation, identification of the source of sepsis, appropriate antibiotic therapy and any necessary surgery to eradicate the focus of infection.
Complications
Sepsis and septic shock can progress to MODS (multi-organ dysfunction syndrome) and MOFS (multi-organ failure syndrome). Patients with MODS often present with sequential failure of organs, lung – liver – intestine – kidney; this may present as ARDS, abnormal LFTs, ileus and renal failure. With continued illness, organ dysfunction progresses to organ failure. Mortality with one-organ failure is around 30%. This rises to 100% with four-organ failure.
Cardiogenic shock
Causes
These can be divided into cardiac compressive, cardiac obstructive or functional. All lead to problems with myocardial function and an inadequate cardiac output.
Symptoms and signs
The traumatic causes will be discussed later in the chapter. Cardiac causes may present with chest pain and collapse. There may be a past history of cardiac problems or presence of risk factors, i.e. diabetes. Patients may be dyspnoeic with signs of pulmonary oedema. The patient may also display the classic signs of shock, i.e. pale, clammy, tachycardia, hypotension. Pulmonary embolism may present similarly (→ Ch. 5).
Investigations
Urgent investigations include portable CXR, FBC, U&E, cardiac enzymes, D-dimers, ABGs, ECG, CXR.
Neurogenic shock
Neurogenic shock is due to impaired descending sympathetic pathways in the spinal cord; this results in loss of vasomotor tone and sympathetic innervation to the heart. This leads to pooling of blood in the lower limbs. Although neurogenic shock can occur with spinal injury, it is not synonymous with spinal shock; this refers to the flaccidity and areflexia seen after a spinal injury. Neurogenic shock also occurs from certain nervous stimuli, i.e. fright – this leads to a sudden dilation of the splanchnic vessels and a bradycardia – the transient hypotension may lead to collapse.
Treatment
In the trauma patient shock should never be assumed to be neurogenic; hypovolaemia is by far the most common cause of hypotension and patients with spinal injury often have concurrent thoracic or abdominal injuries. Management includes:
In the non-trauma setting neurogenic shock is self-limiting.
Anaphylactic shock
Anaphylactic shock is a type I hypersensitivity reaction occurring in response to a previously sensitized antigen. Shock occurs as a result of vasodilation and increased vascular permeability. In surgical practice this may follow administration of drugs or radiological dyes. In the community it may follow wasp or bee stings or ingestion of certain foods, i.e. peanuts.
Trauma
Trauma is the main cause of death in people under the age of 35 years. It constitutes up to 20% of surgical admissions. Mortality can be greatly reduced by appropriate handling of the injured in the following three settings:
Initial assessment of the trauma patient
Pre-hospital care
In the pre-hospital phase, the same priorities exist in terms of ABCs; there is particular emphasis on airway control, control of external bleeding and immobilization. The key is to limit time on the scene and to transfer the patient to the nearest appropriate hospital. Communication with the hospital to allow mobilization of the trauma team is vital.
Major incident triage
Triage is the process of defining the most serious injuries in a mass casualty situation and attempting to have the greatest benefit with the given resources. Multiple casualties implies a number of wounded patients but not sufficient to exceed the ability of the hospital to offer care. Mass casualties implies that the number of injured will exceed the facility’s ability to treat all patients and those with the greatest chance of survival are treated first. In the military, colour categories are applied to the wounded and indicate immediate, urgent or delayed treatment, dead or expectant.
Trauma scoring systems
Scoring systems in trauma can be divided into physiological scores and are based on a patient’s response to injury (e.g. GCS and Revised Trauma Score); anatomical scores based on the injury that has occurred (e.g. Injury Severity Score and Liver Injury Scale); and outcome systems based on the result after recovery (e.g. GCS). Scoring systems are useful for a number of reasons such as facilitating triage, organizing trauma systems and to allow accurate comparisons between populations and treatment methods.
Initial assessment and resuscitation
This should follow ATLS (Advanced Trauma Life Support) guidelines. Initial assessment is divided into a primary survey where patients are assessed and their treatment priorities established based on their injuries, vital signs and mechanism of injury. This is followed by a secondary survey, which does not begin until the primary survey is completed, resuscitation is well established and the patient has normal vital signs.
Primary survey
This process constitutes the ABCDE protocol of ATLS and aims to rapidly identify immediately life-threatening injuries in a sequence in which the most rapidly fatal conditions are diagnosed first (i.e. airway obstruction will be fatal before splenic injury). The ABCDE of the primary survey is below.
ABCDE of emergency management:
During the primary survey and in tandem with examining the patient, certain adjuncts are used, including ECG, pulse oximetry, BP and respiratory rate, insertion of NG tube and urinary catheter (as required); also the patient is provided with adequate analgesia.
Secondary survey
The secondary survey is a head-to-toe evaluation of the trauma patient, i.e. a complete history and physical examination, including a reassessment of all vital signs. Each area of the body should be completely examined. A full neurological examination is carried out including a GCS (Glasgow Coma Score) determination (Table 4.1).
TABLE 4.1 Glasgow Coma Scale (GCS)
Responses | Score |
---|---|
Eye-opening response | |
Spontaneous | 4 |
To voice | 3 |
To pain | 2 |
None | 1 |
Best verbal response | |
Orientated | 5 |
Confused | 4 |
Inappropriate speech | 3 |
Incomprehensible speech | 2 |
None | 1 |
Best motor response | |
Obeys commands | 6 |
Localizes pain | 5 |
Withdraws to pain | 4 |
Flexion to pain | 3 |
Extension to pain | 2 |
None | 1 |
Total | 3–15 |
A score of 3 indicates a severe injury with a poor prognosis. A score of 13–15 indicates minor injury with a good prognosis.
History
This is obtained from the patient (if possible), ambulance staff or other witnesses. Ascertain the time of the accident, the type of accident, the conscious level of the patient at the time of the accident and any change since; any blood loss, details of drugs administered at the scene of accident, previous medical history including drugs and allergies, details of food, alcohol and drug intake. In road-traffic accidents (RTAs), details of the patient’s position in the car, speed, use of airbags/seat belts and degree of damage to the car should be obtained. A mnemonic to help remember this is to take an AMPLE history:
Examination
An initial rapid preliminary examination will have been made during the primary survey. A full examination is carried out during the secondary survey looking for head injuries, maxillofacial injuries, cervical spine injuries, chest injuries, abdominal and perineal injuries, musculoskeletal injuries, and neurological trauma. Typical injuries include:
Investigations
The timing of the investigations depends on the clinical state of the patient. These include: blood grouping and cross-match, FBC, U&E, amylase, LFT, glucose, β-HCG (in women of child-bearing age) arterial blood gas. X-rays in the primary survey include chest and pelvis X-ray. FAST (Focused Abdominal Sonography for Trauma) is an imaging modality often performed during the primary survey to identify an abdominal source of bleeding in a hypotensive patient. All other X-rays, CT, contrast studies, etc. are obtained depending on the stability of the patient and the presence of other injuries. As a rule, these would be obtained as part of the secondary survey. Examples include: spinal X-rays in suspected spinal injury, CT head in patients with head trauma (can often include cervical spine views), CT abdomen and chest in suspected abdominal/thoracic trauma in patients who are haemodynamically stable. Urethrography/cystography in patients with suspected urethral or bladder injury.
Head injury (→ Ch. 18)
Primary brain damage occurring at the time of injury cannot be repaired. Management should be aimed at preventing secondary injury.
Management
The management of specific head injury is dealt with in the section on Neurosurgery (→ Ch. 18) but the basic principles are outlined here as far as trauma management is concerned.
Hypotension in adults is not due to intracranial blood loss. However, in children, significant blood loss can occur in head injuries and can be responsible for hypotension. The scalp should be examined for lacerations and boggy wounds. Observation should be made for bleeding and CSF leakage from the ear and nose. The cranial nerves should be checked and the limbs examined. Assessment of head injured patients include skull X-rays and CT scan; indications for these are detailed in Chapter 18.
Immediate management depends on severity. The presence of abnormal pupillary reflexes, asymmetrical motor signs or deteriorating level of consciousness is an immediate indication for treatment.

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