Plain English Summary
Background and study aims
We are currently undertaking a study to compare the various methods to measure blood pressure in preterm babies. In babies, it is important to keep blood pressure in the normal range as low or high blood pressure can have negative impact on various vital organs, so the accurate measurement of blood pressure is essential. The most reliable method to measure blood pressure is via putting a catheter/arterial line in one of the arteries of the baby and then directly measuring the blood pressure. This is most commonly done by putting the catheter in one of the blood vessels in the umbilical cord. However, this can be a technically challenging procedure and may not be successful at times. Also there can be some complications associated with this if the catheter is left in for a long time. This means that we need a simpler and more reliable method to measure blood pressure. One of the most commonly used methods is an automated system where the cuff is applied to the babies’ arm and a reading comes up on the monitor. The other less commonly used method is a Doppler method. This is a hand held instrument which picks up sounds as the blood flows in the arteries. This is a similar method to cuff blood pressure and does not involve any invasive procedures. It has been found to be closest to the arterial (direct) blood pressure in several studies in older children and adults. The aim of this study is to compare the blood pressures obtained by these methods and find out which method correlates best with arterial blood pressure in very premature babies.
Who can participate?
In this study, we will recruit babies who are less than 28 weeks gestation. These are the babies who are most likely going to need an arterial line inserted as part of their routine intensive care.
What does the study involve?
The study does not involve any extra investigation or blood testing. In addition to the blood pressure measurement by the arterial line, the participating babies will also have their blood pressured measured by two non-invasive methods (Doppler and cuff blood pressure).
What are the possible benefits and risks of participating?
There are no perceived benefits or disadvantages of taking part in this study and all the babies will receive best standard care as any other baby who is not in the study.
Where is the study run from?
Neonatal intensive care unit in James Cook University Hospital in Middlesbrough (UK).
When is the study starting and how long is it expected to run for?
October 2014 to October 2015.
Who is funding the study?
South Tees Hospitals NHS Foundation Trust (UK).
Who is the main contact?
Dr Shalabh Garg
Dr Shalabh Garg
The James Cook University Hospital
Dr Adnan Zafar
The James Cook University Hospital
2014001; IRAS project ID:133892
Non-invasive blood pressure measurement in neonates: comparative analysis of different methods for reliability: an observational study
NiDOP (Non invasive Doppler and Oscillometric Pressures)
The measurement of blood pressure by non-invasive oscillometric method is a common practice in the neonatal units. Several studies have shown that this type of non-invasive blood pressure measurement sometimes over-estimates the blood pressure leading to false reassurance of nursing and medical staff. The accuracy of this method is even more unreliable during the hypotensive periods in this group of patients. The invasive blood pressure monitoring by indwelling arterial catheter (Umbilical arterial catheter or peripheral arterial catheter) is considered to be the gold standard but is not always possible.
The other non-invasive method of blood pressure monitoring is by Doppler ultrasound measurement. This has been shown to be better correlated to arterial blood pressure in various studies. Although the manufacturers claim that with the advancement of technology, the newer generation of oscillometric monitors are better correlated with arterial blood pressure but the recent studies in paediatric and adult intensive care units do not prove this. In spite of the reservations about the reliability of the oscillometric method, it is still used widely in majority of neonatal units and critical decisions are made based on these measurements. The direct blood pressure measurement by placement of arterial catheter is a difficult procedure and is not without complications. Also, once the arterial catheter is removed (usually within a week), accurate measurement of blood pressure measurement is important for management.
We did a pilot survey and found that there are significant variations in practices in terms of measuring blood pressure and treating. There is no proven right or wrong way of measuring blood pressure because of lack of evidence. We hope that this study will provide impetus to adopt a particular method of measuring blood across UK. We conducted this survey to study the variations in practices amongst Level 3 units across England (45 units). We came up with following results:
1. 89% units used both indwelling arterial lines and oscilliometric methods and only 5 units used Doppler in addition.
2. 65% units have written guidelines on the treatment of hypotension.
3. 82% units used dopamine as the first inotropic agent.
4. 40 (90%) units routinely used fluid bolus as first step of treatment of hypotension. Two units used fresh frozen plasma if the perfusion was low after first bolus.
5. 20 units (45%) kept the umbilical arterial lines for as long as needed but the rest of units kept them for different periods (3-14 days).
6. There are 9 different makes of oscillometric monitors that are in use in England and that too with different versions.
The current literature suggests (paediatric, adults and animals) that Doppler blood pressure is better correlated with the arterial blood pressure. In extreme preterm babies, that data is not available. We conducted a pilot survey of all the tertiary neonatal units in England and found that most units still use cuff blood pressure measurements (oscillometric method) in neonates. Through this observational study, our aim is to study which non-invasive method of blood pressure measurements (Doppler versus Oscillometric Methods) in extreme preterm neonates correlates better with arterial (invasive) blood pressure.
NRES Committee North East - Newcastle & North Tyneside 2, REC ref:14/NE/1031
Primary study design
Secondary study design
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Blood pressure management in neonates
Where possible, parents will be approached prior to delivery and given information regarding the trial. If this is not possible then they will be approached soon after clinical decision has been made to put in an umbilical arterial catheter. Clinical team involved with care of the baby will give patient information leaflets to the parents/guardians and offer explanation. Parents/guardians will be given time to read the leaflet and then approached again within 48 hours of arterial catheter placement for consent. Informed written consent for the trial will be obtained from either of the parents/guardians with parental responsibility by members of research team. If consent is given, and providing no contra-indications occur, the baby will be included in the study.
Blood pressure will be measured in the recruited babies by oscillometric/cuff and Doppler methods and will be compared with corresponding blood pressure measurements by arterial catheter. Each baby who has indwelling arterial catheter (umbilical arterial catheter) will have blood pressure measured 4-6 hourly by oscillometric and Doppler methods till the time arterial catheter remains in situ. The blood pressure measured by Doppler method will be recorded under two categories- one obtained at the appearance of sound from Doppler probe and other at the time of appearance of the trace on the pulse oximeter.
Measurements of blood pressure indirectly by cuff and Doppler methods will be done when baby will have cares done routinely by nursing staff. Cares happen every 4 to 6 hours depending upon how sick the baby is. A total of 10 measurements will be taken by cuff and Doppler methods over 24-48 hours coinciding with routine times of cares. After 10 measurements, recruitment of that particular patient will be complete. There will be no effect on routine care of the baby. There are no anticipated side effects.
Primary outcome measure
Correlation of blood pressure measurement by oscillometric/cuff method and Doppler method with direct method of blood pressure measurement from an umbilical artery catheter.
Secondary outcome measures
1. Duration of arterial catheter placement (in days)
2. Inotropic support (Choice and duration)
3. Amount and number of fluid boluses given for hypotension
4. Difference in Doppler blood pressure obtained firstly by appearance of sound and secondly by trace on saturation monitor
5. Complications related to arterial catheters
These will be recorded in case report file.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Any baby born between and including 23+0 and 28+0 weeks of gestation
2. Admitted to neonatal unit
3. Needing arterial catheter placement for clinical reasons
Target number of participants
Participant exclusion criteria
1. Babies with no arterial catheter in situ
2. Babies with any congenital heart disease or cardiac arrhythmias documented on ECG
3. Babies with congenital limb defects
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
The James Cook University Hospital
James Cook University Hospital (UK)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
We intend to present the results in an international meeting as well as publish result in medical journal. The dates are not confirmed as yet.
Intention to publish date
Participant level data
Basic results (scientific)