3 Review: Blood Pressure Blood pressure is the amount of force (pressure) applied to the artery walls.Systolic: The force applied to arterial walls during ventricular systole.Diastolic: The force applied to arterial walls during ventricular diastole.
4 HypertensionChronic hypertension aggravates atherosclerosis and increases vascular resistance (vasoconstriction) within the brain.Positive effects: Increased vascular resistance protects the brain from the damaging effects of systemic hypertension.Negative effects: Predisposes the brain to cerebral ischemia by impairing vasodilator responsiveness. When diastolic BP exceeds 120mmHg, the ischemic brain is at high risk of hemorrhage.
5 Acute on Chronic Hypertension Acute increases in blood pressure superimposed on a chronic hypertensive state.Approximately 50% of all patients positive for an acute ischemic stroke will have a history of preexisting hypertension.On average these individuals will have higher blood pressures post acute stroke than those who were previously normotensive.
6 Blood Pressure Management Treatment of hypertension should be done very cautiously.Neurological deterioration has been associated with precipitous decreases in blood pressure induced by emergency antihypertensive treatment.When blood pressure drops below the lower limit of cerebral blood flow auto-regulation it causes more widespread cerebral hypoperfusion.
7 Blood Pressure Monitoring Ischemic Stroke: Post tPA Vital Signs:Every 15 minutes for 2 hours from start of tPA then,Every 30 minutes for 6 hours then,Hourly for the next 16 hoursTemperature is monitored every 4 hours for 24 hours.
9 Utilized in Ischemic and Hemorrhagic Stroke Standing Orders Labetalol (Trandate)Potent alpha and beta blockerSlows heart rate and decreases peripheral vascular resistanceUse cautiously in patients with constrictive airway diseasesIVP: Given over 1-2 minutes in 10mg increments, can be repeated every minutes (max dose 300mg)Drip: Give a 10mg bolus, followed by a drip started at 2-8mg/minCan be administered in ICU/CCU, ED, PACU, AMB Surgery, Radiology, CardiologyUtilized in Ischemic and Hemorrhagic Stroke Standing Orders
10 Nicardipine (Cardene) Calcium channel blockerDecreases systemic vascular resistance and blood pressureAdministered as an IV infusion, started at 5mg/hour and may be increased by 2.5mg/hour every 15 minutes (max 15mg/hour)Contraindicated for patient’s with conduction deficits (i.e. Second/Third degree heart blocks)Can be administered in ICU/CCU and EDUtilized in Ischemic and Hemorrhagic Stroke Standing Orders
11 Nitroprusside (Nipride) Potent vasodilator used in emergent hypertensive conditionsActs directly on venous and arterial smooth muscleAdminister as an IV drip beginning at 0.3mcg/kg/min, titrate by 0.2mcg/kg/min to desired MAP (max 10mcg/kg/min)Monitor closely for cyanide toxicityCan be administered in ICU/CCU and EDUtilized in the Hemorrhagic Stroke Standing Orders, recommended for consideration in Ischemic Strokes.
12 Cyanide ToxicitySigns and Symptoms: Nausea, vomiting, diaphoresis, apprehension, headache, restlessness, muscle twitching, dizziness, palpitations, retrosternal pain and/or abdominal pain.If this occurs, stop the infusion and symptoms should resolve within 10 minutes, if not then effects are from another source.
13 Utilized in the Hemorrhagic Stroke Standing Orders. Enalapril (Vasotec)An ACE-inhibitor that prevents the conversion angiotensin I to II, preventing vasoconstrictionDecreases peripheral arterial and venous resistanceAdministered IVP at mg every 6 hours as neededContraindicated in patients with hypersensitivity or allergy to ACE-inhibitorsCan be administered in ICU/CCU, ED, PACU, 2CN, AMB Surgery, Radiology, CardiologyUtilized in the Hemorrhagic Stroke Standing Orders.
14 Hydralazine (Apresoline) Potent vasodilator with direct vasodilating effects on the arteriolesAdministered IVP in doses of 5-20mg every six hours as neededContraindicated in patient’s with Rheumatic Heart diseaseCan be administered in ICU/CCU, PACU, ED, AMB Surgery, 2CN, Birthing Center, Radiology, CardiologyUtilized in Hemorrhagic Stroke Standing Orders.
16 Post-Hemorrhagic Stroke Patients are at an increased risk for cerebral vasospasm after spontaneous subarachnoid hemorrhageMedically induced hypertension has proven to reduce vasospasm post bleedMethods:Intra-vascular volume expansion: Used to stabilize vessel walls from spasm/collapseVasopressor support: Vessels are less likely to spasm while acutely constrictedAdministration of anti-diuretics: Assist in the retention of fluids to stabilize vessel walls
17 Cerebral IschemiaUtilization of intra-vascular volume expansion and induced hypertension are effective in reversing ischemic deficits from vasospasm, provided that the treatment commences before the cerebral infarction occurs. If not, ultimately it can be used to prevent further ischemic damage to the cerebrum post infarct.
18 ReferencesPhillips, S. (2004). Pathophysiology and management of hypertension in acute ischemic stroke. Hypertension, 23,Miller, E.L., Murray, L., Richards, L., et al. (2010). Comprehensive overview of nursing and interdisciplinary rehabilitation care of the stroke patient. Stroke, 41,I.V. Push Medication Guidelines. Garden City Hospital department of pharmacy (2010).