Page 566 - ACCCN's Critical Care Nursing

Management of Shock 543

TABLE 20.4 Signs and symptoms of hypovolaemic shock 3

Parameter Mild (15–30% loss) Moderate (30–40%) Severe (>40%)
Blood pressure No change Lowered Hypotensive
Pulse (beats/min) ≥100 beats/min ≥120 beats/min ≥140 beats/min
Respirations >20/min >30/min >40/min
Neurological Normal to slightly anxious Mildly anxious to confused Confused, lethargic
Urine output >30 mL per hour 20–30 mL per hour 5–15, negligible
Capillary refill Normal Reduced >4 sec Reduced >4 sec

the reduced circulating volume, widespread vasoconstric-
tion occurs in most body systems apart from the heart
and CNS; SVR rises markedly in an attempt to retain a Hypothermia
viable circulatory system (this accounts for many of the Temp <35°C
signs and symptoms associated with circulatory compen-
sation). However, as tissues are starved of oxygen and Acidosis Coagulopathy
INR >1.5
pH <7.2
nutrients over a prolonged ischaemic time, local media- SBE >-6 PT >18 secs
tors are released as part of the inflammatory responses, Lactate >4 mmol/L APTT >45 secs
leading to organ microvasculature vasodilation and capil- lonised Ca <1.1 mmol/L Fibrinogen <1.0 g/L
Platelets <50
laries re-open to maintain oxygen delivery and reduce
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hypoxia. This is a hallmark of developing MODS.
Physiological
derangements
NURSING PRACTICE with massive
Clinical management of hypovolaemia centres on mini- transfusion
mising fluid loss and rapid restoration of circulating
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blood volume once the airway and breathing are secure.
More than one large-bore intravenous cannulae are FIGURE 20.1 Physiological derangements of massive blood transfusion.
usually inserted and lost circulating volume is replaced
by colloids, isotonic crystalloids or blood products to
achieve haemodynamic endpoints (e.g. MAP >65 mmHg). Current initiatives of the agency include development
Body heat can be lost rapidly due to blood loss, the rapid and promulgation of evidence based guidelines for both
infusion of room temperature fluids and exposure in the massive transfusion and intensive care.
pre-hospital setting or during repeated physical examina-
tion. It is therefore important to institute measures to Fluid resuscitation
maintain patient temperature >35°C to avoid coagulopa- Fluid resuscitation is a first-line treatment for hypovolae-
thies and loss of thermoregulation. The aim is to ame- mic shock; providing fluid volume increases preload and
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liorate the lethal triad of anaemia, coagulopathy and therefore cardiac output (Starling’s law) and organ perfu-
hypothermia. 40–42 sion. A related principle is that the fluid infused should
Debate surrounds early surgical intervention prior to reflect fluid loss, e.g. plasma replacement in burns, fresh
aggressive fluid resuscitation. The premise is that allow- blood in massive haemorrhage. Giving a ‘fluid challenge’
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ing a lower perfusion pressure prior to achieving haemo- is not always appropriate; the determining factors will be
stasis with controlled or no fluid infusion results in assessment of volume responsiveness, and whether the
less blood loss, due to the compensatory mechanisms infusion will not be deleterious, causing overload, fluid
6
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described above. Use of medications such as Factor IVa shifts and perpetuating inflammatory responses. The
and EPO also remains controversial in the setting of criti- fluid type, volume, rate and targeted endpoints is docu-
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cal haemorrhage. Guidelines for ‘massive transfusion’ mented; often this is structured as a bolus dose in
currently being finalised by the National Blood Authority volume/kg to achieve a measured haemodynamic vari-
(NBA) do not recommend use of Factor IVa beyond able. When massive transfusion is required, attention
licensed indications, although there may be an indication should be given to product selection and hence a proto-
when conventional therapy has failed to secure haemo- col can be employed.
stasis following massive blood loss and transfusion of
blood products. The current debate also includes dosage Independent Practice
and thromboembolic complications associated with Critical care nurses must be efficient and practised at
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its use. The NBA is a statutory agency established in initial patient assessment to establish the degree of
2003 to improve and enhance the management of the compensation occurring in a hypovolaemic patient.
Australian blood banks and plasma product sector. Figure 20.1 highlights clinical manifestations of