Critical Care Mailbag - Isolated Head Trauma
Rob Orman MD and Scott Weingart MD
Take Home Points
▪ Hypotension in a patient with isolated head trauma is worrisome.
▪ Mannitol is a potent diuretic and fluid replacement should match urine output.
▪ Start norepinephrine or push-dose pressors immediately if there is hypotension.
▪ Propofol is a good option for sedation due to neuroprotective effects and despite associated hypotension, which may be managed with pressor support.
● A patient has isolated head trauma with hemorrhage. They do not need surgery immediately. The patient is intubated. The blood pressure is 90 systolic. What is your plan post intubation?
● Why is the patient hypotensive? The patient should be hypertensive. Usually the brain and neurovascular system are trying hard to increase perfusion to the brain. Often you are dealing with intractable hypertension. You should be concerned about hypotension.
● Hypotension from brain swelling does not usually occur until the point of herniation.
● Did the patient get mannitol? People often administer mannitol without realizing that it is a potent diuretic. You need to match the patient’s urine output to avoid hypotension.
● Did the patient get a lot of sedation for intubation? This can cause hypotension.
● Hypotension may sometimes be seen in aneurysmal subarachnoid hemorrhages due to the neurocardiogenic axis effects. This has been reported in other types of bleeds. Patients may develop cardiogenic shock or Takotsubo cardiomyopathy from the brain injury.
● Start norepinephrine or push-dose pressors immediately. Don’t just leave the patient hypotensive for 15-20 minutes while giving them fluids. We know that hypotension and malperfusion, especially in the first 24 hours, is incredibly harmful. You may be adversely affecting your patient’s outcome the longer you leave them hypotensive.
● Did you miss something? Is there a source of bleeding somewhere or neurogenic shock from a spinal injury?
● What is your target blood pressure? We don’t know the answer but in general a MAP of 80 is a reasonable target. This gives you a buffer for a cerebral perfusion pressure of 55-60 assuming an ICP of 20.
● Do you give fluid? If you have it available, you can give hypertonic saline. This may be 3% hypertonic saline or 1-2 amps of sodium bicarb which is 7% hypertonic saline. This will decrease the intracranial pressure and increase cardiac output. Give each amp over about 5 minutes.
● What should you use for sedation?
o Although short acting agents are preferred to facilitate performing an exam, the exam is less important once they are intubated. It is incredibly important to perform a good exam prior to intubation.
o You want a sedative that will also decrease the cerebral metabolic rate, oxygen requirements of the brain and ICP. Propofol is titratable and decreases the cerebral metabolic rate. If the propofol causes vasodilation and decreases the blood pressure, use pressors.
o Try to avoid boluses of propofol as this can trigger large swings in the blood pressure. If you do have to give them a bolus, use a small bolus of 20mg at a time. Start at 20mcg/kg/min and titrate up. Make sure there isn’t a lot of dead space in the IV delaying delivery of the propofol.
● Weingart provides seizure prophylaxis with levetiracetam. There is some suggestion levetiracetam may have worse cognitive outcomes compared to phenytoin but it is much easier to dose and does not require checking levels. These patients should not be on long-term anti-epileptics. In general, prophylaxis is not recommended in non-traumatic bleeds.