Page 548 - ACCCN's Critical Care Nursing

Gastrointestinal, Liver and Nutritional Alterations 525

primary graft non-function, which will not recover, and those studies that appear to have used similar methods,
the only solution is retransplant. 308 has continued to fuel the debate on tight glycaemic
control with some experts urging caution and others
Confirmation of rejection is by liver biopsy but this is not
always possible if the patient is coagulopathic; if the diag- seeing tight glycaemic control as a marker of quality prac-
322
nosis is positive, rejection is treated with high-dose steroid tice. The discrepancies in these studies have been attrib-
pulse therapy, followed by reducing doses of oral predni- uted to many factors including the variability in target
sone. The majority of rejection episodes respond well to ranges for blood glucose, methods of blood glucose mea-
pulse steroid therapy. Previously, treatment with a course surement, difficulty for some studies to achieve separa-
of antilymphocyte (e.g. monoclonal antilymphocyte tion of the treatment and control groups, compliance
globulin, OKT3) 306,307 was recommended, but has now with the therapy, and employment of different nutri-
323
been shown to increase the risk of hepatitis development tional strategies.
in patients with transplants for hepatitis C infections. 309 Our knowledge of tight glycaemic control in the context
of critical illness continues to develop, however, the
Late Complications definitive target for blood glucose in tight glycaemic
Readmission to critical care after liver transplantation is control remains unclear. Nevertheless it is recognised that
not uncommon, with 1 in 5 patients returning due to hyperglycaemia is associated with poorer outcomes and
complications. The most common factors include cardio- therefore should not be neglected. The implications for
pulmonary dysfunction from infection or fluid overload, nursing practice of implementing tight glycaemic control
respiratory failure from collapse and consolidation, in critical care practice are considerable. Incorporating
tachypnoea, recipient age, preoperative liver function, tight glycaemic control into a dynamic setting where
bilirubin, the amount of blood products administered patient acuity regularly and rapidly fluctuates can be chal-
intraoperatively, graft dysfunction, severe sepsis and post- lenging, and consequently requires critical care nurses to
operative surgical complications such as bleeding and have the requisite knowledge and expertise to manage
310
biliary anastomotic leaks. Outcomes are affected by this complex therapy.
intraoperative and postoperative complications, renal
failure, advanced liver disease and malnutrition. 311 Practice tip
GLYCAEMIC CONTROL IN The use of intravenous insulin for tight glycaemic control can
CRITICAL ILLNESS contribute to rapidly changing blood glucose levels therefore
vigilant monitoring is required.
Hyperglycaemia and increased insulin resistance are char-
acteristics of the stress response and activation of the Of particular importance when implementing tight
sympathetic nervous system: adrenal and hypothalamic– glycaemic control, is monitoring for hypoglycaemia.
312
pituitary–adrenal (HPA) axis responses to critical illness. Two large clinical trials of tight glycaemic control –
Hyperglycaemia has been considered a beneficial adap- NICE-SUGAR and the COIITSS Study 324 – reported
314
tive response to stress to provide energy substrate to the reasonably high rates of hypoglycaemia (6.8% and 16.4%
313
organs involved in the ‘fight or flight’ response. respectively), highlighting the need for vigilance in assess-
However, there is some, although inconsistent, evidence ing blood sugar levels. The time and frequency of blood
of the association of hyperglycaemia with high mortality glucose measurement that may be required for some
and morbidity. 313-317 Hyperglycaemia has been associated patients may impact on the provision of patient care, and
with: poor wound healing and higher rates of infection the inability to perform the testing as often as required
after surgery in diabetic patients; higher risk of death after may potentially contribute to underdetection of hypogly-
myocardial infarction in diabetic and non-diabetic caemia. Another potentially important factor that
patients; and poor outcomes after stroke. 313,318,319
may contribute to underdetection of hypoglycaemia is
fatigue in nurses caring for the critically ill. Louie and
Practice tip colleagues. 325 reported the results of a single-centre study
that found the increased number of antecedent shifts
If blood glucose is being maintained at normoglycaemic levels, worked by bedside nurses was associated with an
there is an increased risk of hypoglycaemia. The signs of hypo- increased incidence of hypoglycaemia.
glycaemia are altered mental state, sympathetic stimulation
(tachycardia, sweating) and, in extreme cases, fitting. The validity of blood glucose measurement is also an
important consideration. Many of the studies to date
have measured blood glucose sampled from arterial,
The complexity of the physiological processes associated venous and capillary blood. The use of capillary blood in
with hyperglycaemia in critical illness and the sophisti- testing blood glucose may be problematic, particularly in
cated research required to generate valid information those patients for whom hypoperfusion is an issue. 326-329
renders clinical decision-making related to glycaemic Techniques to measure blood glucose include point-of-
control challenging. Since the first landmark study of care testing meters, blood gas analysers and formal labo-
320
glycaemic control in the critically ill, there have been ratory testing. Formal laboratory testing is considered
at least 26 randomised controlled trials investigating tight ‘gold standard’ for blood glucose measurement although
321
glycaemic control. Contradictory results, even from the delay in receiving has resulted in point-of-care testing