Circulation

In the primary survey the state of the circulation is quickly assessed by observation of:

• skin colour and temperature

• pulse rate and volume

• capillary refill time at a finger pulp or nail bed (usually 2 seconds or less)

• BP (blood pressure)

• JVP (jugular venous pressure) and heart sounds

• level of consciousness (in the patient who has not sustained a brain injury).

Hypotension with a raised JVP and absent heart sounds suggests cardiac tamponade: → p. 78.

The assessment of hypovolaemia in the trauma patient is difficult because of the following:

• The interaction of autonomic reflexes, head injury, pain, drugs and blood loss is complex.

• Compensatory mechanisms may prevent a fall in systolic blood pressure until 30% of the blood volume has been lost.

• Rapid blood loss may produce a reflex bradycardia.

• In elderly people, tachycardia may not be present as a result of a limited cardiac response to catecho-lamines or treatment with β blockers.

• Haematocrit is an unreliable index of shock; a nearly normal value does not rule out significant blood loss.

All abnormalities of colour, pulse, BP and consciousness should be regarded with suspicion.

Methods of assessing organ perfusion → Box 2.8.

Signs of shock → Box 2.7.

The blood loss potential of evident injuries should be considered (→ Table 2.1); the mechanism of injury may suggest occult blood loss. Hypovolaemia is seldom caused by head injury alone, except occasion-ally in infants. Open fractures will cause greater blood loss than similar closed injuries.

Tx 

General management of major haemorrhage → Figure

1.2 on p. 8.

• Control external blood loss by direct pressure at the bleeding site.

• Insert at least two large-calibre (14 G) cannulae into large veins. If percutaneous venous access is diffi-cult, use the interosseous route. Alternatively, cut down to the antecubital veins or the long saphen-ous vein or insert a long line into the femoral vein.

Central veins should not be used as routes for fluid

Box 2.7 Signs of shock

•  Altered mental state

•  Delayed capillary refill (>2 s)

•  Tachycardia

•  Pale, cool skin

• In prehospital management of patients with pre-sumed blood loss, IV fluids should not be adminis-tered if a radial pulse can be felt or, in the case of penetrating torso injuries, if a central pulse can be felt. In the absence of these pulses, IV crystalloids should be administered, en route to hospital, in boluses of not more than 250 mL (5 mL/kg for infants and young children) until the relevant pulse becomes palpable.

• Consider the possibility of intra-abdominal bleed-ing and the need for surgical advice.

• Consider the possibility of blood loss from a major pelvic fracture. Do not try to ‘spring’ the pelvis to demonstrate its instability – this may increase bleeding. Vessel damage is difficult to identify sur-gically, instability is best treated with an external fixation device, which can be applied rapidly in the ED by the orthopaedic team. This should be thought of as a resuscitation manoeuvre to help control the circulation in the primary survey.

Military anti-shock trousers (MASTs) or pneumatic anti-shock garments (PASGs) are no longer recom-mended. Controlled trials have not shown them to be of benefit and their sudden removal causes signifi-cant volume loss into the lower limbs.

The return of a normal BP after the infusion of, for example, 1000 mL does not mean that only a litre has been lost – the true amount is likely to be much higher. When blood pressure can be maintained only by continuing infusion, cardiovascular collapse is imminent; the cause of the hidden blood loss must be sought.

Failure to respond to fluids usually means inade-quate transfusion or unrecognised fluid loss. However, it may also be caused by:

• tension pneumothorax → p. 74

• cardiac tamponade → p. 78

• myocardial infarction

• acute gastric distension

• neurogenic shock → p. 51.

Blood transfusion

Indications for blood components→ Box 14.29 on p. 258.

Overview of the management of major haemorrhage

→ Figure 1.2 on p. 8.

replacement in the initial stages of resuscitation, but should be preserved for use in the ICU.

• Take a sample of blood (20 mL in an adult) for group and cross-match, and coagulation screen.

• Commence rapid fluid replacement with a bolus of 10 mL/kg. After reassessment of the patient, this can be repeated. A ratio of crystalloids to colloids of 50 : 50 is safe. Some prefer Hartmann’s solution to 0.9% saline if large volumes are to be given. The role of hypertonic saline in resus-citation looks promising but has yet to be fully established. Ideally, IV fluids should be warmed to 40°C.

Box 2.8 Guides to organ perfusion

•  Mental state

•  Urinary output: adequate volume replacement  produces a urine output in the adult of about  50 mL/h

•  Arterial blood gases: metabolic acidosis  implies inadequate tissue oxygenation  requiring increased oxygen and fluids (not  bicarbonate)

•  Shock index: calculated by dividing the pulse  rate in beats/min by the systolic BP in  mmHg. The normal range is 0.5–0.7. Values 

>0.9 suggest significant haemorrhage

•  Core/periphery temperature gradient

•  Aortic flow (measured by Doppler ultrasound  probe)

•  Serum lactate: high lactate is increasingly  recognised as a good indicator of tissue  hypoxia and a poor prognosis

•  ICU determination of oxygen demand and  supply

Table 2.1 Estimation of traumatic blood loss in an  adult (closed injuries)

Site Volume (L)

Pelvis 0.5–3

Shaft of femur 1–2

Tibia 0.5–1

Chest >2

Abdomen >2

Arm 0.5–1

Forearm 0.5–1

Military surgeons avoid ‘old blood’ and crystalloids and use large volumes of whole blood with fresh frozen plasma (FFP).

Control of severe bleeding

Modest haemodilution and a fall in haematocrit to 30% improve erythrocyte passage through the micro-circulation. This allows optimal oxygen delivery to the tissues – until the haematocrit falls below 25%.

However, when estimated blood loss exceeds 1.5 L in an adult, blood should be transfused to maintain the haematocrit >25% or a haemoglobin concentration

>8 g/dL.

SAG-M blood (which consists of plasma-poor red blood cells in saline, adenine, glucose and man-nitol) is frequently supplied by the National Blood Service in the UK. (The adenine maintains 2,3- diphosphoglycerate or 2,3-DPG activity in stored blood to allow more normal uncoupling of oxygen from oxyhaemoglobin and thus improved tissue oxy-genation.) This red cell concentrate is presented in units of 300 mL, each with a packed cell volume (hae-matocrit) of 0.55–0.65.

If a blood sample is taken when the initial intrave-nous lines are established, grouped blood (type spe-cific) should be available within 20 min. Cross-matched blood (whether by urgent or full cross-match) is seldom available within 1 h and is therefore not normally appropriate for unstable hypovolaemic patients. These patients should receive blood that is matched only for the recipient’s ABO and rhesus group. This will, of course, increase the incidence of transfusion reactions.

In situations of such urgency that delay – even for grouped blood – is unacceptable, O-negative (univer-sal donor) blood should be given. However, the risks of a transfusion reaction must be outweighed by the benefits of immediate blood replacement; such occa-sions are rare.

Rapid blood transfusion may produce the following:

• Coagulopathy: requiring platelets and/or FFP

• Hypocalcaemia: as a result of calcium binding by anticoagulants in stored blood (at infusion rates of

<50 mL/min this should not be a problem); plasma calcium must not be allowed to fall <1 mmol/L

• Hypothermia (which may itself cause a significant reduction in coagulation).

Thus, if a large volume of blood is transfused rapidly, it should be filtered and warmed.

Immunocompromised and pregnant patients should always receive CMV-negative blood (i.e.

blood that is free of cytomegalovirus).

The ‘coagulopathy of trauma’ is due to many factors: consumption of fibrinogen and clotting factors, dilution of plasma proteins, hypothermia, acidosis, inflammation and shock. If present on admission, it is associated with a mortality rate of almost 50%.

In the presence of intractable bleeding, deficiency of clotting factors should be considered and haema-tological advice sought. In particular, in the absence of any known disease, acquired haemophilia may be a possibility (→ p. 257). If a site for bleeding is identi-fied, further investigation should never delay surgical attempts to ‘turn off the tap’.

Tranexamic acid: tranexamic acid inhibits fibrinoly-sis. It has been shown to safely reduce mortality in bleeding trauma patients without increasing the risk of adverse events, provided that it is given within 3 h of the time of injury. It is particularly useful when other treatments directed at coagulopathy (e.g. FFP, platelets and cryoprecipitate) are unavailable. A loading dose of 1 g is given intravenously over 10 min, followed by an infusion of 1 g over the next 8 h.

Recombinant factor VIIa: recombinant factor VIIa (rFVIIa or activated eptacog alfa) is licensed for the treatment of bleeding in patients with inhibitors such as congenital and acquired haemophilia, inherited factor VII deficiency and Glanzmann’s thrombasthe-nia (→ p. 258). It may also be a useful treatment in patients with continuing severe haemorrhage despite optimal surgical management and on-going attempts to correct coagulopathy. It is more effective if used early in the course of bleeding and, for maximum benefit, it should be given before the onset of the complications associated with a massive blood trans-fusion. Every effort should be made to correct defi-ciencies in platelets and coagulation factors by administering appropriate platelet, plasma and cryo-precipitate, or fibrinogen concentrate transfusions, before considering treatment with rFVIIa. Treatment with factor VII is expensive and may not be suitable for all patients, especially those with risk factors for thromboembolic disease or disseminated intravascu-lar coagulation. It is not derived from human blood and is therefore acceptable for use in Jehovah’s Witness patients. The dose is 90 mcg/kg (4.5 kIU/kg) by slow IV bolus injection and this can be repeated after 2 h if there is still significant blood loss. If there is no response after two doses, further amounts should not be given. Full blood count (FBC), pro-thrombin time (PT), activated partial thromboplastin

clothing is disturbed. Some clothes can only be safely removed during log-rolling. The areas most often missed are the back and the perineum.

time (APTT) and fibrinogen should be measured before treatment and 20 min after factor VII has been given. The PT will shorten dramatically and the APTT may also be reduced. However, these effects do not last long and further monitoring is required accord-ing to the clinical situation. It may be appropriate to consider bilateral lower limb ultrasonography to check for deep venous thrombosis (DVT) 3–5 days after rFVIIa administration.

Haemostatic substances for local application:

severe bleeding from damaged tissue, blood vessels or even organs may sometimes be controlled by the local application of haemostatic substances. The most effective of these is MPH (Microporous Polysac-charide Hemospheres), a patented powder synthe-sised from raw materials de rived from potatoes!

The MPH particles dehydrate the blood and concen-trate blood solids on their surfaces, thus creating a high concentration of gelled, compacted. clotting material.

Emergency thoracotomy

Emergency thoracotomy may be life saving for some patients with penetrating injuries to the chest (→

p. 79). A left anterolateral thoracotomy in the fourth intercostal space allows cardiac tamponade to be relieved; cross-clamping of the thoracic aorta opti-mises cerebral circulation during the critical period.

Thoracotomy is of no value if the patient is already lifeless on arrival at the department or has sustained blunt trauma.