Screening films At an early stage in the assessment of a patient with multiple injuries, screening films of the cervical spine, chest and pelvis should be obtained. Where there is the possibility of an abdominal injury with intra-abdominal haemorrhage an ultrasound examination should be carried out. If the circumstances dictate and allow, the opportunity may be taken at this stage to arrange an X-ray examination of any limb injury, or any injury to the skull or facial bones.
Fluid replacement If the patient fails to be stabilised by the administration of crystalloids, then blood will be required. Normally, blood will also be required if the haemoglobin falls below 9 g/dL. Note the following points:
1. If the patient is exsanguinated, and will die unless blood is administered immediately, give two units of Group O Rhesus negative blood pending supply of cross-matched blood. The latter should ideally should become available not more than 20 minutes after the patient's blood sample is submitted to the blood bank.
2. Thereafter, or if the situation is less acute, administer cross-matched packed red cells. If bleeding continues, then whole blood becomes more appropriate.
The volume of the replacement required can van' enormously, and therefore must be judged by the response: see the following flow chart (Fig. 2.1 )for a summary of replacement management.
Assessing the response to replacement There is varying opinion on the best methods of assessing the stability of the circulation and the success of resuscitation. In all. the degree and maintenance of a positive response to treatment is more important than the reading of isolated values. Many methods are advocated including the following:
1. Pulse and blood pressure. In spite of some unreliability, these remain the most valuable guides. The initial aim should be to restore the pulse rate to less than 140. and to obtain a blood pressure in excess of 90 mm systolic and rising.
2. Urinary output. Aim at 0.5 mL/kg body weight per hour in an adult (ie. 6 mL every 10 minutes in a 70 kg man) and 1.0 mL/kg body weight in a child (i.e. twice the rate per kg).
3. Central venous pressure (CVP). This allows the monitoring of atrial filling pressures. (Normal value = less than 10 mmHg.)
4. Haemoglobin. If the Hb level reaches 10 g/dL and remains there, further blood is not usually required. (Below 9 g/dL. blood will usually be required, and virtually invariably below 7 g/dL. When the Hb lies between 7-10 g/dL. and there is doubt, the Pv02 and LR (see below) may be helpful in defining transfusion requirements). In the absence of continuing bleeding, one unit of packed red blood cells would be expected to raise the Hb level by lg/dL.
5. Pulmonary Artery Pressure (PAP): A pulmonary artery catheter allows the measurement of pulmonary artery pressure and has been particularly advocated in the elderly patient. (Normal values: systolic = 15-28 mmHg: diastolic = 5-16 mmHg.)
6. Pulmonary Capillary Wedge Pressure (PCWP): (Normal value, mean = 6-12 mmHg.)
8. Cardiac index (CI): This represents the circulating blood volume per minute. (Normal value = 2.8—4.2 L/min.)
9. Systemic vascular resistance (SVR): (Normal value = 11 - 18 mmHg.)
10. Arterial-alveolar oxygen difference (AaD02): (Normal = 10 mmHg.)
11. Peripheral/body core temperature difference: This gives a useful assessment of prolonged shock.
12. Mixed venous partial pressure of oxygen (P,02): This is a guide to the tissue oxygen supply and is normally 6 kPa. 45 mmHg. If the patient's condition is stable no treatment is indicated until a critical level of 3 kPa. 23 mmHg is reached.
13. Extraction ratio (ER): This is the ratio of oxygen consumption to oxygen delivery, and normally is around 25%. It equals:
where Ca02 = arterial oxygen; Cv02 = venous oxygen.
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