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Hypertension & Acute Neurologic Patients                           
Rodrigo Rodriguez,Jr. MD  Dec. 7, 2001 KP Conference

Cerebral Perfusion Pressure (CPP) = MAP - ICP   (Normal range 70 - 100 mmHg) Mean Arterial Pressure (MAP) = (SBP + 2 DBP)/3 Intracranial Pressure (ICP) = 5- 15 mm Hg normally

Summary Statement:

• In acute neurologic illness CPP takes on a linear relationship with MAP
• Beta-adrenergic blocking agents as Labetalol are agents of choice in neurologic illness.
• ACE Inhibitors are second line agents
• Vasodilators should be avoided if possible
• Nitroprusside may be used with caution in severe HTN

For Intracerebral Hemorrhage patients:

• Rebleeding may occur if the Bp remains elevated
• Optimal target BP should take into account the premorbid degree of Hypertension
• Target Mean Arterial Pressure MAP of 120-130 mmHg

For Ischemic Stroke patients:

• Usually are hypertensive on admission
• Cerebral autoregulation is impaired
• Regional CBF (Cerebral Blood Flow) becomes pressure-dependent
• Elevated BP may be needed to aid blood flow to the ischemic prenumbra
• Target MAP of 120-140 mmHg

For Traumatic Brain Injury patients:

• Increased Bp may be secondary to a hyperadrenergic state vs elevated ICP
• Elevated ICP will decrease CBF
• Target MAP of 110-120 mmHg or a CPP of 70 mmHg

For Hypertensive Encephalopathy patients:

• It is an hypertensive emergency
• Co-existent cerebral vasospasm
• Autoregulation breaksdown
• Both ischemia and cerebral edema develop
• Decrease MAP slowly by 25% over hours to avoid cerebral hypoperfusion.

Final Clinical Conclusions:

• CPP should be maintained between 70 - 100 mmHg
• CPP can be adjusted by controlling the MAP
• CPP can be achieved by maintaining a MAP of 100-120 mmHg
• Elevated ICP wil decrease CPP
• Labetolol does not affect cerebral vascular tone and is the first choice agent .

REF:

The Diagnosis and Management of Hypertensive Crises  (Review)
(Chest. July 2000;118:214-227  American College of Chest Physicians)

How to manage blood pressure in critically ill neurologic patients.  
(Journal of Critical Illness  April, 2001)

       12182001

Antihypertensive agents frequently used in neurologically ill patients Mechanism Initial (bolus)
Ref: How to manage blood pressure in critically ill neurologic patients.  (Journal of Critical Illness  April, 2001)

Medication	Mechanical of action	Initial bolus dose	Infusion rate	Advantages	Disadvantage
Labetalol	Alpha & Beta antagonist	5-20 mg IV q15min (Max: 340 mg)	0.5 - 2 mg/min	Rapid onset of action No effect on ICP	CHF, bronchospasm, Bradycardia
Esmolol	B1 selective blocker	500 ug/kg over 1 min	50 - 200 mg/kg/min	Rapid onset of action No effect on ICP	Bradycardia
Nicardipine	Ca-blocker	none	5 - 15 mg/h	Rapid onset of action	Hypotension, increase ICP & heart rate
Na-Nitroprusside	Vasodilator	none	0.25 - 10 ug/kg/min	Rapid onset of action Short duration of action	cyanide toxicity, increase CBF, ICP
Nitroglycerin	Vasodilator	50 ug IV	5 - 200 ug/min	Rapid onset of action Short duration of action	Methemoglovin production, increase CBF, ICP
Clonidine	Alpha 2 agonist	0.1 - 0.2 mg PO	not available	May be helpful in alcohol withdrawal syndrome	decrease CBF
Hydralazine	Vasodilator	2.5 - 10 mg IV q20-30 min (Max 40 mg)	usually used as boluses	Good antihypertensive effect	Longer duration of action, increase CBF, ICP; lupus like syndrome, hemolytic anemia, glomerulonephritis
Enalaprilat	ACE inhibitor	0.625 - 5 mg IV q6h	usually used as boluses	no efect on ICP or CBF	may cause abrupt decrease in BP; potential for increased ICP in pts with poor intracranial compliance; renal dysfunction

12182001