Hypertensive Episode Clinical Trial
Official title:
A Multicentre Cross-sectional Study of the Prevalence of Hypertensive Disease in Patients Presenting for Elective Surgery in the Western Cape
Hypertension is a major medical and public health burden throughout the world. It is estimated that 1 in 3 adult South Africans are diagnosed with hypertension, however detailed statistics reflecting the burden of disease are somewhat lacking. The implications and effects of poorly controlled hypertension and its associated co-morbidities are significant and extensive. In South Africa, hypertension is the single most prevalent cardiovascular risk factor and predominant contributor to cardiovascular disease and mortality.
RESEARCH PROBLEM:
Although the diagnosis of hypertension and initiation of treatment is most frequently made
in the primary health care setting, the perioperative period provides clinicians with a
unique opportunity to identify patients with hypertensive disease, educate patients about
the disease, and, if appropriate, initiate appropriate therapy. Furthermore it provides the
opportunity to refer patients for further investigation or follow up at peripheral health
care centres for ongoing management. The identification and diagnosis of hypertension as
well as the effective management thereof is a primary health care target and serves as an
efficient health care strategy in reducing long-term cardiovascular morbidity and mortality,
as well as the burden of disease associated complications. There are however, a multitude of
reasons to investigate and treat persistent hypertension in the perioperative period. The
long-term end organ effects are numerous and add significantly to patient morbidity and
mortality. Appropriate blood pressure control has an important long term impact on patient
outcome. In the acute peri-operative setting the significance of hypertension is however
less clear.
AIMS & OBJECTIVES:
Aim of the Study:
The primary aim of the study is to identify and categorise the prevalence of hypertensive
disease in adult patients presenting for non-cardiac, non-obstetric elective surgery in all
surgical disciplines at 1 tertiary level institution and 6 secondary hospitals over the
determined period of the study.
The secondary aims of the study will include the following 1) categorise the degree of
hypertensive disease in the study population 2) identify associated target organ damage and
associated risk factors 3) determine patient compliance to treatment.
In a sub-study, the primary objective will be to explore the relationship between
pre-operative blood pressure measurement and intra-operative hypotension (mean arterial
pressure (MAP) < 55mmHg for > 1minute as defined by Walsh et al.
In order to achieve the aims of the study the following objectives will be sought:
Objectives of the Study related to the prevalence of hypertension:
1. Prevalence and degree of hypertensive disease in adult patients presenting for
non-cardiac, non-obstetric, elective surgery in all surgical disciplines with elective
theatre lists over the period of the study will be determined by measuring and
recording preoperative blood pressure during the pre-assessment anaesthetic
consultation and/or immediate preoperative period, using an automated oscillometric
blood pressure measurement technique. If the blood pressure is noted to be elevated,
two additional readings at least 10 minutes apart will be performed. The lowest
recorded blood pressure will be used. The study will identify patients with
preoperative in hospital blood pressure measurements as follows:
- SBP<140 mmHg and DBP <90 mmHg
- SBP<160 mmHg and DBP<100 mmHg
- SBP<180 mmHg and DBP<110 mmHg without end organ damage
- SBP<180 mmHg and DBP<110 mmHg with end organ damage
2. Compliance to anti-hypertensive treatment will be assessed using the Morisky Medication
Adherence Questionnaire.
Objectives of the sub-study related to the association of pre-operative blood pressure
measurement and intra-operative hypotension:
1. Any episodes of low blood pressure defined as a mean arterial pressure of less than
55mmHg will be recorded as well as the cumulative time spend below this threshold.
METHODOLOGY:
Study Design & Data Collection:
This is a prospective quantitative study at one tertiary and six secondary level
institutions involving data collected on adult, non-cardiac, non-obstetric patients
presenting for elective surgery for a period of one week (from Monday at 7am to Friday at
7pm).
Data is to be collected by the anaesthesiology registrars and consultants providing
anaesthetic services to elective patients, in all surgical disciplines, over the one-week
period of the study.
Quantitative data will be recorded on a clinical reporting form (CRF) evaluating:
- General demographic information e.g. age, gender, ethnicity
- General medical information e.g. co-morbid conditions, risk factors for hypertension
- Presence of target organ damage which will be assessed by the presence of appropriate
electrocardiographic changes, presence of impaired renal function (elevated creatinine)
and/or the presence of retinopathy
- General surgical information e.g. indication for surgery and type of surgery
Study Population & Sample Size:
The study population will involve patients presenting for elective non-cardiac,
non-obstetric, surgery who are 18 years of age or older and are able to give consent. For
the prevalence of hypertension and compliance to treatment part of the study, all patients
regardless of the planned anaesthetic technique will be included. For the sub-study, looking
at the pre-operative blood pressure and its association with intraoperative hypotension only
patients who receive a general or neuraxial anaesthetic will be included. For the sub-study
only, this effectively excludes patients who undergo some form of sedation or local block to
facilitate their procedures e.g. cataract extraction.
Measurements:
Blood pressure measurements will be performed with an appropriately sized non-invasive blood
pressure cuff, using an automated oscillometric method of blood pressure measurement.
Recruitment & Consent:
Participants will be recruited by convenience sampling. All patients compliant with the
inclusion criteria will be included in the study. Data obtained will be collected by various
anaesthesiology registrars and consultants, and will not include any specific patient
information, thus ensuring patient anonymity. Demographic, medical and surgical information
is generally routinely available prior to anaesthetic and surgical intervention.
Furthermore, blood pressure measurements are routinely performed and documented. Obtained
details will be captured on a clinical reporting form and so patient records will not be
altered or removed for study purposes. Finally, no additional measurements, tests or
investigations will be performed which might place the patient at risk, or discomfort, or
impose any additional cost or burden on patient or institutional resources.
Data Management & Analysis:
Data capture forms will be collected and collated. The information will be captured in Excel
for further statistical analysis.
Patients will be risk adjusted for:
- Duration of surgery
- Need for blood transfusion intra-operatively
- Pre-operative anaemia
- ASA status
- Functional status
- Major surgery
- Type of anaesthesia (Dependant on sample size)
ETHICAL & LEGAL CONSIDERATIONS:
To ensure complete anonymity, no personal patient information or details will be recorded on
the data collection form. As this is an audit, and the researcher will not be involved in
delivery of anaesthetic care to the patients in the study, it will be the responsibility of
the anaesthesiology registrars and consultants providing the anaesthetic, to ensure patient
safety and well-being, at all times. This is routine, good practise and the study will not
influence or detract from these patient specific clinical decisions or patient management in
any way.
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