PERIOPERATIVE NUTRITIONAL SUPPORT IN SPECIAL SITUATIONS
Modifications of the standard adult formulae are required for
the treatment of patients with congestive cardiac failure and hepatic failure. Modifications
of the solutions are often necessary, depending on the patient's metabolic response.
It is essential for the anesthesiologist to recognize that no single nutrient solution,
parental or enteral, can be ideal for all situations. Nutritional support services
are becoming a feature of modern critical care units. These consulting services,
which may employ critical care anesthesiologists among their medical staff, must
consider the following special situations for nutritional support.
The Neurosurgical Patient
Three cautions should be remembered when TPN is being considered
for the brain-injured patient (see Chapter
53
):
- Severe head injury is associated with hyperglycemia, and administration
of large amounts of glucose can worsen this abnormality.[16]
- Free water administration is usually restricted after brain trauma to prevent
severe hyponatremia.
- Some brain-injured patients exhibit the cerebral salt wasting syndrome
and require increased sodium administration.
- The greatest hazard of TPN is sepsis. This risk should not be underestimated
in critically ill patients bearing numerous catheters and multiple possible foci
for infection.
Animal experiments employing controlled degrees of cerebral ischemia
have demonstrated that elevated blood-brain glucose concentrations greatly enhance
the extent and the degree of subsequent brain damage.[205]
Pulsinelli and associates[206]
examined the effect
of hyperglycemia versus normoglycemia in nondiabetic patients with stroke. These
workers reported that stroke-related deficits among nondiabetic patients appeared
to be more severe when the admission blood glucose level was above 120 mg/dL than
when it was below this level. This finding is consistent with the work of Van den
Berghe's group evaluating the deleterious effect of hyperglycemia on critical care
unit mortality.[24]
Pulsinelli and colleagues[206]
concluded that hyperglycemia could accentuate ischemic brain damage in humans and
suggested that blood glucose levels be maintained in the near-normal range in diabetic
patients with a high risk of stroke. They also suggested that glucose-containing
infusions should be avoided in the immediate treatment of patients with acute or
progressive stroke, in patients undergoing surgery that could affect cerebral blood
flow (e.g., carotid endarterectomy, extracranial-intracranial bypass, cardiac bypass),
or in those who have had a cardiac arrest.
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