Page 463 - ACCCN's Critical Care Nursing

440 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

Near-Infrared Spectroscopy haemorrhage, episodes of angiographic cerebral vaso-
Near-infrared spectroscopy (NIRS) is a non-invasive spasm were strongly associated with reduction in trend
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method of monitoring continuous trends of cerebral in the ipsilateral NIRS signal. Furthermore, the degree
oxygenated and deoxygenated haemoglobin by utilising of spasm (especially more than 75% vessel diameter
an infrared light beam transmitted through the skull. reduction) was associated with a greater reduction in
Oxygenated and deoxygenated haemoglobin have same-side NIRS signal demonstrating real-time detection
different absorption spectra and cerebral oxygenation of intracerebral ischaemia.
and haemodynamic status can be determined by their
relative absorption of near-infrared light. NIRS allows SUMMARY
interrogation of the cerebral cortex using reflectance
spectroscopy via optodes, light transmitting and This chapter provides an overview of anatomy and physi-
detecting devices, placed on the scalp. Normal satura- ology in the context of and in application to neurological
tion is 70%. Because NIRS interrogates arterial, venous, assessment of the critically ill. Priorities of clinical assess-
and capillary blood within the field of view, the derived ment are described in terms of the critically ill patient.
saturation represents a regional tissue oxygenation (rSO 2 ) Imaging techniques and assessment incorporate the
measured from these three compartments and can be therapeutics of intracranial pressure, cerebral perfusion
used to identify tissue hypoxia and ischaemia in the pressure and partial brain tissue oxygenation monitor-
brain cortex. ing, cEEG, transcranial Doppler and cerebral perfusion
imaging. The research vignette reports how alcohol
The clinical and bedside use of NIRS is constrained by intoxication impacts upon clinical assessment using the
potential sources of error, which include contamination Glasgow Coma Scale score. The clinical case examples
of the signal by the extracerebral circulation (such as in neurological assessment priorities in an unstable, trau-
the scalp), extraneous light, and the presence of extravas- matic brain injury patient. Clinical, non-invasive and
cular blood arising from subarachnoid or subdural haem- invasive assessment techniques are described within the
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orrhage. In a recent study in patients with subarachnoid context of this patient’s care.

Case study
On the 30th August, a 24-year-old male, Daniel, was riding his trail skin pink in colour, peripherally cold and pale; capillary refill
bike on a dirt road. Whilst negotiating a corner he collided at high >4 seconds.
speed with a truck and was dragged under the truck for approxi- ● Disability: He was unresponsive, GCS 3; pupils: left 3 mm and
mately 60 metres. He was wearing a helmet. At the scene his GCS right 5 mm non-reacting. Daniel was intubated using thiopen-
was 3 and his pupils, sized 3 mm in diameter, were reacting sequen- tone, fentanyl and rocuronium and mechanically ventilated in
tially to light. Rib and severe bilateral femur fractures were evident combination with physiological fluid resuscitation.
to the attending paramedics who applied compression to the
profusely-bleeding femur. Daniel’s helmet was removed; his airway Secondary survey
was maintained and the cervical spine immobilised, his chest The secondary survey revealed the following details.
decompressed by needle thorocentesis on the left side. Intrave- ● Head: scalp clear, nil abrasions. CT revealed widespread
nous access was obtained and normal saline infused. Oxygen was petechial haemorrhages consistent with diffuse axonal injury,
administered and Daniel was transferred to the nearest trauma acute subdural haemorrhage with midline shift of the ventri-
tertiary centre by helicopter. cles, hairline base of skull fracture and cerebral oedema with
poor differentiation between grey and white matter.
● Face: No oedema; rhinorrhoea and otorrhoea from both
Emergency Department
Arrival to the Emergency Department (ED) was 20 minutes later. nostrils and ears.
Daniel bypassed triage and was admitted to the resuscitation area ● Neck: Stiff neck collar left in situ; no obvious lacerations
where members of the trauma team conducted primary and sec- observed around neck area; no evidence of tracheal deviation.
ondary surveys. On presentation, Daniel’s vital signs were: heart Cervical spine CT reported no bony injury, spine not cleared;
rate 134 beats/min, respirations 8 breaths/min with paradoxical with a stable L4 pedicle fracture.
chest rise and fall, blood pressure 93/65 mmHg, mean arterial pres- ● Chest: Obvious chest deformity and instability of sternum and
sure (MAP) 74 mmHg, SaO 2 unable to obtain, temperature 34.9°C, ribs; paradoxical chest rise and expansion; decreased air entry
with a GCS of 3. bilaterally, no subcutaneous emphysema. Bilateral pulmonary
contusions, left haemopneumothorax diagnosed on review of
Primary survey the chest X-ray; a left sided chest drain was inserted.
Daniel’s primary survey revealed the following details. ● Abdomen: Firm, no abnormal distension, some bruising. IDC
● Airway: Upper airway cleared. Cervical spine: Status unknown, insertion revealed haematuria.
collar in situ. ● Pelvis: Bruising bilaterally with no obvious deformity.
● Breathing: Hand ventilated on 12 L/min at 14 breaths/min, ● Back: Marked flank bruising, no lacerations, right perinephric
paradoxical chest rise and fall, generalised poor air entry, haematoma on CT; rectal tone present. Upper limbs: Obvious
decreased bilaterally, no tracheal deviation. deformity of right arm; X-ray revealed right radial and ulna
● Circulation: Tachycardic, hypotensive, and hypovolaemic; fractures, lacerations and bruising present; pulses present.
pulses present on palpation except for the right popliteal ● Lower Limbs: Bilateral femur fractures – right one compound;
and dorsalis pedis; temperature centrally warm, well perfused, lacerations and extensive bruising; pulses absent right side.