AAGBI/Anaesthesia Research Grant

Intraoperative Hypotension in Elder Patients: An
Observational Study of Intraoperative Hypotension in Older
Patients in the UK (iHypE)

Dr Daniel Martin

Low blood pressure during surgery (intraoperative hypotension or IOH) is thought to be a common occurrence but the rate is unknown in the UK. It happens as a side effect of the medicines used during an anaesthetic. In patients aged over 65 years this is associated with an increased risk of heart attack, stroke, kidney failure and death following surgery. Defining IOH and its incidence in the UK is therefore a crucial step towards future studies investigating the effect of IOH treatment on patient outcome in the UK.

We aim to determine how often IOH occurs in patients aged 65 years and over throughout the UK. A secondary objective is to identify the blood pressure Anaesthetists consider to be too low and how they treat this low blood pressure. This applied definition might be a major contributor influencing the rate of IOH measured.

We will conduct this multi-centre study throughout the UK using an established trainee research network. Instances of IOH, its magnitude, duration, and treatment will be identified from anaesthetic records. Other key medical and demographic information will be recorded for each patient. Data will be collected for a total of 48 hours at each hospital. Patients included in the study will be followed up to assess their postoperative course up to 30 days after surgery including: stroke, heart problems, kidney injury or death after surgery. All information will be obtained from patient records. A second component of the study involves administering a questionnaire to Anaesthetists in participating hospitals. The questionnaire will ask about individual practice in relation to the treatment of low blood pressure during surgery. The anonymised responses will be collected and assessed to determine national consensus on this topic.

Expected impact
We will quantify for the first time the prevalence of IOH in older patients across the UK, and the treatment thresholds regularly employed clinically. This may be a key target for future quality improvement. We plan to use this data combined with patient outcomes to power a future study investigating the effect of tighter blood pressure control on patient outcome in the UK.

The impact of blood pressure thresholds on perioperative mortality in non-cardiac surgery in a United Kingdom database

Professor Jonathan Hardman

Surgery is conducted in millions of patients each year with increased blood pressure (BP) and on long-term medication, and yet we know relatively little about how we should care for these individuals around the time of surgery to assure the best outcomes. Our recent findings show that low (but not high) blood pressure (before surgery) is associated with increased risk of death following surgery and that different drugs exert different effects on the risk of death after surgery at different blood pressure levels. Having established an important effect on death after surgery, the purpose of this study is to define whether there are certain blood pressure levels (i.e. very low or very high) that are associated with an increased risk of complications such as heart attacks or strokes, and to determine whether blood pressure variability affects risk.

We will also seek to determine whether certain drugs used for blood pressure management have lower risks than others. We will identify whether the same blood pressure levels that predict increased risk of death extend to other (non-fatal) complications and confirm whether certain long-term medications are associated with increased risk. Our future aim is to conduct a randomised, controlled clinical trial to show whether adjusting patient care according to BP level, during the preparation for surgery in the community and in the perioperative environment, would improve perioperative mortality or other complications.

In order to fulfil this ambition, further information is required to: (1) confirm that our recent findings that perioperative blood pressures less than 119/63 mmHg are associated with increased risk of death after surgery extend to other adverse events (such as postoperative heart attacks or strokes), and (2) that the drugs identified as affecting the risk of death exert plausible effects on other adverse events after surgery (such as heart attacks or strokes) and (3) understand the BP thresholds in specific vulnerable cohorts (such as prior stroke, heart attacks, heart failure, renal failure, and diabetes). Understanding the impact of perioperative blood pressure variability (the tendency to change over time) could also help identify patient groups (e.g. those with increased variability) that need to be treated differently to the rest of the cohort.

The incidence of chronic headache and low back pain after accidental dural puncture with a Tuohy needle and epidural blood patch in the obstetric population: a prospective 2-group cohort study

Dr Niraj Gopinath

Headache can be a complication after insertion of an epidural needle for pain relief during labour. The headache is called Post Dural Puncture Headache (PDPH). PDPH causes significant short-term disability, prevents mobilisation, affects childcare activities and results in prolonged hospital stay. Initial treatment involves painkillers and if patient fails to respond, an Epidural Blood Patch (EBP). EBP involves taking patient's blood and injecting into the epidural space. It is generally agreed that PDPH is a self-limiting condition and resolves in two weeks. However there is emerging evidence that patients with PDPH could be at an increased risk of developing longstanding (chronic) headaches. A retrospective case study showed that 28% of patients who developed PDPH had longstanding headaches at 18
months after the insertion of the epidural. There is also recent evidence of new onset low back pain developing in patients who have received an epidural blood patch that was performed to treat PDPH. Nearly two thirds of patients from a hospital in UK had new onset low back pain after they had received epidural blood patch treatment. Presently, there is no prospective clinical study evaluating the development of longstanding headaches and new onset low back pain after the development of PDPH.

The aim of the present study is to evaluate the incidence of longstanding headache after postdural puncture headache and the incidence of new onset low back pain after epidural blood patch treatment.

The proposed study is a prospective, cohort study that will be conducted at two centres (Leicester and Derby) over 36 months. Index participants who suffer PDPH will be matched with control participants who have received an uneventful epidural insertion. The index and control participants will be matched for age, body weight, parity and the type of delivery. Mothers who have longstanding headache or low back pain will be excluded from the study. After providing written consent, the participants will be provided with a questionnaire pack containing three sets of two questionnaires to be completed at 6, 12 and 18 months after developing the headache as well as stamped envelopes to return the questionnaires to the research team. A research team member will perform telephone follow up 6, 12 and 18 months to encourage completion of the questionnaires. Participation in the study will end at 18 months after completion of the study questionnaires.

Patient & Public Involvement
There is a PPI representative involved in the design and conduct of the proposed study. Mrs T Kirby is an occupational therapist and had suffered postdural puncture headache during the delivery of her second child. She developed longstanding headache and is under the treatment of the chronic pain team. She continues to work full time and is keen to raise the awareness of the potential for development of chronic headaches following PDPH.

Ethical approval
Application for Regional Ethics Committee approval to be submitted once funding is approved as per University Hospitals of Leicester NHS Trust Research & Development guideline.

Pressure Area Distribution On A Variety Of Clinical Surfaces In A Group Of Volunteers

Dr James Jack

Pressure damage to the skin and underlying tissues happens when the pressure acting on an area is greater than the blood pressure supplying it. The tissues are short of oxygen, toxins build up and tissue damage starts. It is particularly common in areas such as your heel or tail bone. Treatment of this condition causes much distress to patients and costs the NHS an estimated £1.4-2 billion per year.

During a patient's stay in hospital, they lie on lots of different surfaces, some for long periods of time. Pressure damage can happen at any point. To date no studies have looked at when patients might be at risk of pressure damage during their hospital stay. Particular areas we'd like to look at are the emergency department and the period when patients go for operations. Whilst their time on these areas is quite small compared to their total stay, these are the times with the greatest potential for pressure damage. It is thought that up to 55% of pressure damage can be related to a patients' time in the operating theatre. Being exposed to high pressures in theatre could begin the process of pressure damage that could become apparent later in their stay.

We propose a snap shot study in a group of healthy volunteers with a range of weights and Body Mass Index (BMI: a calculation based on your height and weight), laying on surfaces a patient would be exposed to during their hospital stay. Volunteers would lie on a variety of surfaces they may find themselves on during an emergency admission to Hospital, including operating tables, and in a variety of positions. Their pressure distributions in each scenario would be measured with a specialised pressure sensing mattress.

After data collection is complete we will analyse it using statistics, review practices in our own hospital, and publish it in the scientific literature.

We hope to establish the pressure distributions of current patient surfaces in use, to find any points in the patient's journey when they are at risk of developing pressure damage. Given the annual cost of pressure damage to the NHS, the potential for improving patient care and reducing the costs associated with pressure damage are vast. The findings of this study could lead to the comparison and improvement of existing practices and surfaces, and potentially result in improved pressure area care.