Blood pressure measurement over time

Measuring Blood Pressure Change over Time... 

A clinical trial involving an antihypertensive drug requires assessing blood pressure change over time, which necessitates measurements at two time points or more. Imagine a clinical trial in which the treatment phase lasts 12 weeks. A baseline measurement is obtained for each subject before the start of the treatment phase, and a subsequent measurement taken at the end of the treatment phase. In practice, it is also likely that measurements will be taken at various specified intervals during the treatment phase. 

If a stroke patient receives intravenous (IV) thrombolysis, care often continues in the ED until the patient arrives in the ICU. Close monitoring must continue during this time, with special attention to the blood pressure. The blood pressure is most commonly checked via an arm cuff, since the placement of invasive lines (e.g., arterial catheterization) is relatively contraindicated once the patient has received intravenous thrombolysis (unless the situation is emergent and mandates such treatment). The systolic pressure must not exceed 185 mm Hg, and the diastolic pressure limit should be 110 mm Hg. Should the blood pressure exceed these limits, IV antihypertensive agents should be administered. IV pushes of labetolol (10-20 mg over 1-2 minutes) may be effective, but if patients are refractory to these initial measures then a continuous infusion of labetolol (0.5-2.0 mg/minute), nicardipine (5-15 mg/hour), or nitro-prusside (0.25-10 mg/kg/minute) may be necessary to keep the patient s blood pressure within the range. There will be a more detailed discussion of these antihypertensive agents, including their side effect profiles, later in this chapter. 

Compound LY231617 was given at a dose of 10 mg/kg i.v. over a period of 5-7 min beginning 1 h after MCAO. Reperfusion occurred at 2 h after MCAO and at that time the rats received 5.0 mg/kg i.v. for 24 h. Mean arteriai blood pressure (MABP), heart rate, arteriai blood pH, PO2 and pCOi were measured. Body temperature was regulated at 36-37°C for the entire 24 h period. 

In a study at the University of North Carolina involving about nine thousand men and women over a period of 11.6 years, the rate of cardiovascular disease increased significantly as blood pressure levels increased. Compared with patients who had optimal blood pressure levels, those with high-normal measurements had two and a half times the risk of developing cardiovascular disease. That statistic took into consideration other factors involved in the disease. Most of the risk was in the form of a stroke. The risk was greatest for African Americans, diabetics, overweight and obese individuals, and people with high levels of LDL cholesterol. 

Measuring change in blood pressure over time... 

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