Page 568 - ACCCN's Critical Care Nursing

Management of Shock 545

therefore be monitored for signs of tetany, hypotension guidelines has been developed and the massive transfu-
47
and electrocardiographic evidence of hypocalcaemia. As sion guideline is complete and will be followed by a
stored blood ages, plasma potassium levels rise (possibly number of other specialised guidelines. All guidelines
to over 30 mmol/L). Hypokalaemia may be more will be available to download from the National Blood
common as red cells begin active metabolism and intra- Authority website as they are completed (see Online
cellular uptake of potassium restarts with transfusion. 47 resources).
Acid–base disturbances may also be evident due to the
stored blood lactic acid levels and the citric acid. Citrate CARDIOGENIC SHOCK
metabolises to bicarbonate, and a profound metabolic
alkalosis may result from massive blood transfusion. As Cardiogenic shock manifests as circulatory failure
49
hypothermia causes reduced citrate and lactic acid meta- from cardiac dysfunction, and is reflected in a low
2
bolism, an increase in the affinity of haemoglobin to cardiac output (CI <2.1 L/min/m ), hypotension (SBP
oxygen, platelet dysfunction and an increased tendency <90 mmHg) and severe pulmonary congestion, high
47
for cardiac dysrhythmias, the patient and the blood central vascular filling pressures (CVP; PAOP
50
transfused should be warmed to avoid complications. >18 mmHg). Additional invasive parameters are: intra-
2
thoracic blood volume index >850 mL/m ; global end-
2
Leucocyte depletion occurs during donation in Australia diastolic volume >700 mL/m ; and extravascular lung
and decreases up-regulation of the inflammatory immune volume index >10 mL/kg. 51,52 Cardiogenic shock is com-
response associated with transfusion. Current clinical monly associated with AMI and manifests when 40% or
practice guidelines for the administration of blood prod- more of the left ventricle is ischaemic. It is also related to
ucts and red cells to stable adult patients are listed in mechanical disorders (e.g. acute cardiac valvular dysfunc-
Tables 20.5 and 20.6. A new structure with multiple tion or septal defects), deteriorating cardiomyopathies or

TABLE 20.5 Clinical practice guidelines for red blood cell and platelet administration
Appropriate Use of Blood Components
For Stable Adults & Children >4 months (corrected) age
Adapted from NHMRC/ASBT guidelines (www.anzsbt.org.au)
Haemoglobin is NOT the sole deciding factor for transfusion – consider other patient factors e.g. signs of hypoxia and ongoing blood loss.
Red Cells
Hb Considerations
<70 g/L Transfusion is often clinically useful unless early Hb recovery is expected. A threshold of <60 g/L may be
appropriate for children.
70–100 g/L Likely to be appropriate during surgery with major blood loss or if there are signs or symptoms of
impaired oxygen transport.
>80 g/L May be appropriate to control anaemia-related symptoms in a patient on a chronic transfusion regimen
or during marrow suppressive therapy.
>100 g/L Not likely to be appropriate unless there are specific indications
WHAT DOSE?
Red Cells (mL) = 0.4 × wt (kg) × (desired – actual) Hb (g/L)
Platelets
Use of platelets is likely to be appropriate as prophylaxis for:
Indication Considerations
9
9
Bone Marrow Failure At a platelet count of <10 × 10 /L in the absence of risk factors and <20 × 10 /L in the presence of risk
factors (e.g. fever, antibiotics, evidence of haemostatic failure)
Surgery/Invasive To maintain platelet count at >40 × 10 /L. For surgical procedures with high risk of bleeding (e.g. ocular
9
9
or neurosurgery) it may be procedure appropriate to maintain at 100 × 10 /L
Platelet Function Disorders May be appropriate in inherited or acquired disorders, depending on clinical features and setting. In this
situation, platelet count is not a reliable indicator
Use of platelets is likely to be appropriate as therapy for:
Bleeding Any patient in whom thrombocytopenia is considered a major contributory factor.
Massive Bleeding/Transfusion Confined to patients with thrombocytopenia and/or functional abnormalities who have significant
bleeding. Often with platelet count <50 × 10 /L (<100 × 10 /L with diffuse microvascular bleeding).
9
9