Page 468 - ACCCN's Critical Care Nursing

Neurological Alterations

and Management 17

Di Chamberlain
Wendy Corkill

of diseases such as stroke, brain and spinal cord injury,
Learning objectives and status epilepticus. This chapter discusses the concepts
that underlie neurological abnormalities and addresses
After reading this chapter, you should be able to: current management techniques and modalities.
● differentiate cerebral hypoxia from cerebral ischaemia and
focal from global ischaemia CONCEPTS OF NEUROLOGICAL
● differentiate between primary and secondary brain injuries DYSFUNCTION
due to brain injury
● relate the procedures of selected neurodiagnostic tests to This section discusses the concepts of neurological
dysfunction including altered levels of consciousness,
nursing implications for patient care motor and sensory function and cerebral metabolism
● discuss the rationale for medical and nursing management and perfusion.
in the care of the brain-injured patient.
ALTERATIONS IN CONSCIOUSNESS
In critical illness, impaired consciousness is often the first
sign of a severe pathological process. Consciousness is
Key words defined as recognition of self and the environment, which
requires both arousal and awareness. There are different
coma types of depressed consciousness through to coma, the
cerebral perfusion most severe form of absolute unconsciousness.
neuroprotection
intracranial hypertension Altered Cognition and Coma
seizures Coma is a state of unresponsiveness from which the
traumatic brain injury patient, who appears to be asleep, cannot be aroused by
stroke verbal and physical stimuli to produce any meaningful
spinal cord injury response; therefore, the diagnosis of coma implies the
absence of both arousal and content of consciousness.
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meningitis Coma must be considered a symptom with numerous
subarachnoid haemorrhage
causes, different natural modes, and several management
modes.
Stupor is a state of unconsciousness from which the
INTRODUCTION patient can be awakened to produce inadequate responses
to verbal and physical stimuli.
There are numerous conditions encountered in critical
care areas that relate to serious neurological dysfunction. Somnolence is a state of unconsciousness from which the
While most are associated with critical illness, or at least patient can be fully awakened. Although there are many
well defined, several others are very infrequent and specific causes of unconsciousness, the sites of cerebral
not addressed extensively in this chapter. One problem affection are either the bilateral cerebral cortex or the
arises in that the onset of an abrupt neurological com- brainstem reticular activating system. The commonest
plication is frequently obscured by the effects of the causes of bilateral cortical disease are deficiencies of
primary illness. For example a metabolic disorder pro- oxygen, metabolic disorders, physical injury, toxins, post-
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ducing encephalopathy can delay recognition of an intra- convulsive coma and infections. The reticular activating
cerebral haemorrhage, or by its treatment, such as using system maintains the state of wakefulness through
sedation to allow greater synchrony with a mechanical continuous stimulation of the cortex. Any interruption
ventilator. However, neurological alterations are generally may lead to unconsciousness. The reticular activating
defined by problems that derive from the acute aspects system can be affected in three principal ways: by 445