The following is based on Dr. Weingart’s Podcast 129 – LAMW: The Neurocritical Care Intubation July 26, 2014 and on the Emergency Neurologic Life Support Course.
It is important to understand that everything in this post only applies to patients who have Subarachnoid Hemorrhage, or Intracerebral Hemorrhage and who are hypertensive. In these patients we do not want to cause a spike in blood pressure from all the sympathetic stimulation that occurs from placing and having an endotracheal tube in place. This strategy also applies to the aortic dissection or suspected aortic dissection that has very high blood pressure [and not to the hypotensive aortic dissection]
Dr. Weingart recommends using video laryngoscopy in these cases as it allows the [expert] operator to use much less force to expose the glottis and hence hopefully cause much less reflex sympathetic response.
The patient who is hypotensive should not receive the treatments discussed in this post as these treatments would make the hypotension worse (much worse).
BP Management (1):
AHA and Neurocritical Care Society guidelines [1, 2] acknowledge the lack of quality data about BP control in SAH patients and suggest only that the blood pressure should be monitored and controlled to ‘‘balance the risk of stroke, hypertension-associated rebleeding, and maintenance of the cerebral perfusion pressure’’ . That said, retrospective data suggest a higher rate of rebleeding with systolic BPs above 160 mmHg. Current guidelines suggest treating extreme hypertension in patients with an unsecured ruptured aneurysm. Modest BP (mean arterial pressure, or MAP, <110) does not require treatment. Pre-morbid BPs should be considered and used to inform the risks and benefits of treatment. Experts in the field use anti-hypertensive medications that are short acting, easily titratable, and can be administered as an IV drip to reduce the systolic pressure to below 160 mmHg, or the MAP <110, keeping in mind the principles mentioned-above.
4.5 Blood Pressure Management
- Precise guidelines for BP management do not exist (see Bederson et al,Guidelines for the management of aneurysmal SAH; Stroke (2009) 40:994)
- Many specialists recommend SBP < 140 in a patient with no history of hypertension. SBP > 150 has been associated with aneurysmal re-rupture, and over treatment of BP can lead to brain ischemia (especially if hydrocephalus is present).
- Use short acting, titratable medications such as labetalol or nicardipine
- Avoid long-term nitroprusside due to concern of raising ICP
So for the patient with SAH we want to control extremely high blood pressure with the treatment goal noted above.
Intubating the Patient with Presumed Elevated Intracranial Pressure (ICP) (2):
Intubating the Patient with Presumed Elevated Intracranial Pressure (ICP)
In the prehospital and ED environment, clinical evidence of increased ICP is inferred from clinical signs of brain herniation that include altered mental status plus a unilaterally dilated pupil, bilaterally dilated and fixed pupils, and decerebrate or extensor posturing (decorticate posturing is not predictive of elevated ICP) . Since ICP measurement is usually not available in these situations, one should proceed with the assumption that ICP is elevated, assuming a value of at least 20 mmHg for ICP in these circumstances. When the airway is manipulated, two responses may result in even more increased ICP: the reflex sympathetic response (RSR), which results in increased heart rate, increased blood pressure, and, consequently, increased ICP; and the direct laryngeal reflex that stimulates an increase in ICP independent of the RSR .
Although the RSR may be dangerous in a hypertensive patient, pre-treatment of the RSR is not indicated in a hypotensive patient with known or suspected increased ICP . Elevations in ICP should be mitigated by minimizing airway manipulation (the most experienced person should perform the intubation) and administering medications.
So we want to control the high blood pressure with nicardipine IV before we intubate the patient who needs intubation [oxygenation failure, ventilation failure, inability of pt to protect airway, anticipated neuro or cardiopulmonary decline requiring transport or immediate treatment] and who is dangerously hypertensive.
Here is how we control the BP with nifedipine (3):
• Begin with IV 5 mg/h.
• Titrate up by 2.5 mg/h at 5–15 min intervals to a
maximum total dose of 15 mg/h.
• When desired BP has been attained, reduce to 3 mg/h
And because we want to prevent the reflex sympathetic response from intubation [in neuro patients who are dangerously hypertensive], we want to give IV fentanyl (2 – 3 micrograms per kilogram) three minutes before our planned intubation because it takes that long to work (2):
At doses of 2–3 micrograms/kg, attenuates the RSR associated with intubation, and is administered as a single pre-treatment dose over 30–60 s in order to reduce chances of apnea or hypoventilation before induction and paralysis . It is generally not used in patients with incipient or actual hypotension, or those who are dependent on sympathetic drive to maintain an adequate blood pressure for cerebral perfusion.
Dr. Weingart suggests that the dose of fentanyl to prevent Reflex Sympathetic Response to intubation in these patients should be 5 micrograms per kilogram.
But Dr. Weingart reminds us that:
All equipment [and] meds must be prepared before administration. Someone must be watching the pt. You need to have push-dose epinephrine drawn up at the bedside if you are going to use fentanyl in these doses.
And we want to pre-oxygenate and denitrogenate the patient prior to intubation [again, this is not a patient who needs a crash intubation].
We place a nasal cannula at 15 l/min O2 under a non-rebreather mask also at 15 l/min O2 for three minutes.
And before we perform the RSI we need to get a preintubation neurological examination that includes an assessment of (2) :
- Level of arousal, interation, and orienation
- Cranial nerves
- Motor function of each individual extremity
- Tone & reflexes
- Subtle or gross seizure activity
- Cervical spine stability
- When spinal cord injury is suspected, assess sensory level.
And the neuro critical care intubation, if indicated, is needed for the patient with intracerebral hemorrhage who is dangerously hypertensive(4):
Hematoma expansion is common in patients with acute ICH, and this is associated with worse outcomes [6,17].Although the pathophysiology that leads to hematoma expansion is incompletely understood, it tends to occur early (within a few hours of onset), and coagulopathy increases the frequency of its occurrence and its extent. However, hematoma expansion is common even in patients without coagulopathy or who are not receiving antithrombotic medications. Thus, intervention to address treatable aspects should not be delayed pending patient disposition.
(6) Effectiveness of nicardipine for blood pressure control in patients with subarachnoid hemorrhage. [PubMed Abstract] [Full Text HTML] [Full Text PDF] J Cerebrovasc Endovasc Neurosurg. 2012 Jun;14(2):84-9. doi: 10.7461/jcen.2012.14.2.84. Epub 2012 Jun 30.
(7) Effectiveness and safety of nicardipine and labetalol infusion for blood pressure management in patients with intracerebral and subarachnoid hemorrhage. [PubMed Abstract] Neurocrit Care. 2013 Feb;18(1):13-9. doi: 10.1007/s12028-012-9782-1