Question 15

Created on Tue, 05/12/2015 - 19:46
Last updated on Thu, 09/24/2015 - 00:34
Pass rate: ?
Highest mark: ?

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The following information relates to a patient being cared for in your ICU with an isolated severe traumatic brain injury. The patient is heavily sedated and unresponsive.

A photograph of the patient bed-space and monitor, as well as the ventilator settings, arterial blood gas analysis, and plasma biochemistry results are provided.

Based on these data, what therapeutic interventions would you perform in this patient? 
Give your reasons.

Photographs of bed space and monitor omitted.

...From cheating and looking at the answer, one can establish that the photograph depicts a trauma patient lying flat in bed, with a cervical collar on, an ETT fixed with ties, and an EVD drainage bag hanging well above their head.

The monitor displays the following values:

  • CPP = 45mmHg
  • ICP = 35mmHg
  • Temperature = 38.1°

Ventilator Settings:

  • SIMV mode 
  • FiO2 0.3 
  • Tidal Volume 450ml 
  • RR 18
  • PEEP 5

Parameter

Result

Normal Adult Range

Barometric pressure

760 mmHg (100 kPa)

pH

7.38

7.35– 7.45

PCO2

45 mmHg (10.5 kPa)

3545 (4.6 – 6.0)

PO2

100 mmHg (5.0 kPa)

Bicarbonate

26 mmol/L

22 27

Sodium*

150 mmol/L

134 – 146

Potassium

4.0 mmol/L

3.4 – 5.0

Chloride*

114 mmol/L

100 – 110

Urea*

10.1 mmol/L

3.0 – 8.0

Creatinine

104 µmol/L

50120

Glucose*

15 mmol/L

3.0 – 7.0

Measured osmolality*

330 mOsm/Kg

280 – 300

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College Answer

  • Head up – bed currently flat. Elevation to 15-30 degrees may be beneficial for ICP control.
  • Remove cervical collar – jugular venous compression may elevate ICP
  • Assess ETT ties and if tight replace with alternative fixation method –same rationale
  • External ventricular drain is too high – should be lowered
  • Drainage of CSF given ICP of 35
  • CPP is currently 45. Increase CPP (either by reducing ICP or increasing MAP)
  • Consider paralysis; paralysis indicated if patient coughing or posturing and to prevent shivering with temperature control techniques.
  • Increase respiratory rate; CO2 is 45 – aim for 35-40mmHg
  • Control glucose – hyperglycaemia associated with worse outcome in head injury.
  • Temperature is 38.1 – fever associated with elevated ICP; Cool to normothermia initially.
  • Consider osmotherapy with hypertonic saline targeting Na+ to 155

Discussion

This question really asks, "how well do you know the Brain Trauma Organisation Guidelines for Management of Traumatic Brain Injury?" This is discussed in detail elsewhere.

It is difficult to make up a specific answer for this without the monitor photograph. From the college answer, one can predict what the picture would have contained.

In any case, whatever the stimulus photograph, the principles are are all the same:

Maintaining cerebral oxygen supply:

  • Normoxia: keep the PaO2 above 60 mmHg
  • Normotension: measure the MAP, and keep the systolic above 90mmHg
  • Intracranial Pressure monitoring: keep it under 20mmHg
  • Cerebral perfusion pressure: keep it 50-70mmHg
  • Cerebral oxygenation monitoring:keep the SjO2 >50%, and PbrO2 >55mmHg
  • Managing increased intracranial pressure for which there is a variety of strategies:
    • Draining the EVD ( about 20ml/hr, max)
    • Positioning the head straight
    • Removing the C-spine collar
    • Sedation :
      • Propofol sedation to decrease distress and thus decrease ICP
      • Barbiturate coma if other methods of lowering ICP have failed
      • Analgesia to prevent increased ICP in response to suctioning and routine care
    • Paralysis
    • Osmotherapy
    • Controversial measures
      • Decompressive craniectomy
      • Hypothermia
      • Dexamethasone

Decreasing cerebral oxygen demand:

  • Sedation
    • Propofol sedation to decrease distress and thus decrease ICP
    • Barbiturate coma if medical and surgical methods of lowering ICP have failed
  • Analgesia - opioid selection is irrelevant, but opiate boluses increase ICP
  • Seizure prophylaxis is infrequently indicated, and the course is 7 days only

Controversial measures:

  • Decompressive Craniectomy
  • Hypothermia

References

Our beloved Oh's Intensive Care manual has two excellent chapters to dedicate to this topic:

Chapter 43 (pp. 563) Cerebral protection by Victoria Heaviside and Michelle Hayes, and

Chapter 67 (pp. 765) Severe head injury by John A Myburgh.

There are also the Brain Trauma Organisation Guidelines for Management Traumatic Brain Injury, which one might describe as a definitive reference.

It is debatable as to which of these sources is more out of date. At the time of writing, the BTF guidelines have not been updated since 2007. Oh's Manual has undergone a more recent revision, but is not exactly a well-accepted source of guidelines.