Blood Pressure Management - Essay Example

Blood Pressure Management in Acute Stroke: A Long-Standing Debate Aim: It has been established that high systolic and diastolic Blood Pressure (BP) are correlated with risk of stroke. The lowering of BP protects against first time occurrence as well as recurrence of stroke. More than 80% of the stroke patients have high BP values. At present there are two contrasting approaches either of lowering the BP in the setting of acute stroke or that of leaving it untreated. The arguments in former of the former approach include reduction of risk of recurrence of stroke, prevention of subsequent edema and prevention of re-bleeding accompanied by expansion of haematoma in patients with cerebral bleeding. The second approach is based on the fact that the elevated blood pressure under these conditions is necessary for continued blood supply to the ischaemic regions where the normal autoregulation has been damaged as well as for maintenance of cerebral perfusion pressure. Therefore, there is no clear consensus for the management of arterial hypertension associated with acute stroke. In order to address this problem, the author has analyzed a large number of studies that present contrasting results on the correlation between BP levels and outcome in Ischaemic Stroke (IS) and Intracerebral Haemorrhage (ICH) patients. Therefore, the author seeks to address the issue by summarizing the existing evidence for both the approaches and to examine the recommendations for management of BP in view of the ongoing clinical trials in this area. Methods: In order to review the data, the author included observational studies and intervention trials. The data from observational studies was collected by searching of the electronic PubMed database with relevant keywords. Publications of observations of baseline value of BP and its correlation with possible outcomes like death, dependency, recurrent stroke and neurological deterioration were included. All trials of the preliminary, safety or randomized controlled type were identified by searching the Pubmed and Cochrane databases with relevant keywords to determine the effect of BP lowering drugs on outcome. Conclusions: The arguments in favor of and against the control of BP were made on the basis of analysis of the above observational studies. It was found that in IS, the BP values return to normal within a short span of IS. Also, lowering of BP during this stage may be detrimental to the rescue of the ischaemic area by treatment as it lowers the perfusion pressure. This is more critical in view of the fact that cerebral autoregulation is dysfunctional under conditions of acute IS and the passive perfusion is completely dependent on the perfusion pressure. Thirdly, the persistent blood pressure may be a required compensation for the occlusion of the blood vessel. However, a large body of data indicates poor outcome in patients with post IS hypertension and is a powerful argument in favor of treatment for lowering of BP. In case of ICH, the BP values spontaneously return to normal within a few days of the episode. Further lowering of BP in this case may serve to lower the cerebral perfusion pressure and thus damage the affected brain tissue. However, as in the case of IS, high BP levels have poor correlation with patient recovery and clinical outcome. Thus, patients with elevated ICH values after ICH are associated with death, deterioration, cerebral oedema, haematoma and recurrent haemorrhagic stroke. The author goes on to discuss the U shaped relationship, which indicates that either extremely low or high BP values affect clinical outcome adversely. Analysis of data from clinical trials was also done. The outcome of treatment with several types of antihypertensive drugs in IS has been reviewed. Data from small randomized clinical trials has already demonstrated the safety and efficacy of transdermal nitric oxide (NO) donors, that serve to lower BP by vasodilation. However, beta blockers that may drastically reduce the BP were not found to be suitable for lowering of BP. Several other studies were either inconclusive or ended prematurely. In case of ICH, though very little data is available, mild lowering of the BP has proved to be safe and may even lower the neurologic deterioration and haematoma expansion in treated patients. Initial evidence of favorable outcomes of raising the BP has also been reviewed. The limitations of the data have been discussed and guidelines given for future studies. At the end of the manuscript, the recommendations of the European Stroke Initiative and Stroke council of the American Stroke Association for the management of BP in IS and ICH patients have been presented in light of the foregoing discussion. Analysis of the data and methods used. The search of the electronic databases was made using the keywords blood pressure, hypertension, acute, stroke, outcome, prognosis, death, mortality and ICH. Thus, twenty studies from year 1989 to 2005 detailing data from 23,723 patients were analyzed to determine the relationship between the admission base line BP values and the three month outcome in patients with IS. Ten studies in a total of 4,154 patients from 1987 to 2005 were analyzed in patients with ICH. A list of the included studies with the year of publication, mode and time of recording of BP, number of patients and summary of the results of the study was made. In both types of data, additional sources were found from the citations included in the studies. The authors excluded redundant and insufficient data. Most of the data from interventional trials was either absent or inconclusive. Randomized controlled trial (RCT) data is critically required for making pertinent conclusions. Especially, a double blind RCT study has been recommended to explore the initial favorable results from elevation of BP in acute phase post ICH patients. More statistics are likely to emerge from several ongoing trials. The data from different observational studies has been combined in a meta-analysis but it may have certain inbuilt variables that can lead to conflicting observations. Some of these variables include method of data recording, study variable, selectivity of patients and type of variables studied etc. Future interventional clinical trials should, in addition to being RCT should have the same time window for measuring the BP levels, should include carotid ultrasound examination, should take safety issues of carotid artery patients into account and should be supported by Doppler, SPECT or PET scanning. Analysis of why this work is important or different from others This work is significant as it updates the current knowledge in this important and controversial area. The last reviews presenting the situation were published several years before (1,2). At the time there were ongoing clinical trials that could have yielded data on the correct therapeutic approach. However, most of the data even till the present time has been insufficient to address the problem satisfactorily. This is due to the limitations of the study design, which have been discussed and specific guidelines laid down in the present article. The work also discusses the currently used scientific guidelines for the management of hypertension in acute phase of stroke in view of the analysis of the evidence from various studies. Thus, it helps practitioners understand the scientific basis of the recommendations made. It is also different from Ref. No. 3 that deals with the same problem solely in neurologic emergencies. References 1. Robinson TG, Potter JF. 2004. Blood pressure in acute stroke. Age Ageing 33(1):6-12. 2. Kanji S, Corman C, Douen AG. 2002. Blood pressure management in acute stroke: comparison of current guidelines with prescribing patterns. Can J Neurol Sci. 29(2):125-31. 3. Talbert RL. 2006. The challenge of blood pressure management in neurologic emergencies. Pharmacotherapy 26(8 Pt 2):123S-130S. Read More