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Trial registered on ANZCTR


Registration number
ACTRN12615000160538
Ethics application status
Approved
Date submitted
5/02/2015
Date registered
18/02/2015
Date last updated
25/04/2024
Date data sharing statement initially provided
17/12/2018
Date results information initially provided
25/04/2024
Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of lying in the prone position on blood pressure in women with preeclampsia, women with gestational hypertension and healthy pregnant women
Scientific title
Prone position for the reduction of blood pressure in women with preeclampsia, women with gestational hypertension and healthy pregnant women
Secondary ID [1] 285928 0
Nil
Universal Trial Number (UTN)
U1111-1165-8450
Trial acronym
P3 study
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 294113 0
Preeclampsia 294114 0
Gestational hypertension 294115 0
Pregnancy 294161 0
Condition category
Condition code
Cardiovascular 294430 294430 0 0
Hypertension
Reproductive Health and Childbirth 294490 294490 0 0
Fetal medicine and complications of pregnancy

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Women rest in the left lateral position for 5 minutes (timed by one of the study investigators) and then they have haemodynamics, respiratory rate and oxygen saturation measured. The women are then placed in the prone position and rested for 5 minutes (timed by one of the study investigators) and then then have haemodynamics, respiratory rate and oxygen saturation measured. The women then return to the seated or lateral position.
Intervention code [1] 291112 0
Other interventions
Comparator / control treatment
Resting in the left lateral position for 5 minutes (supervised by a member of the research team) the resting for 5 minutes in the prone position (supervised by a member of the research team).
Control group
Active

Outcomes
Primary outcome [1] 294228 0
blood pressure change using an automatic sphygmomanometer
Timepoint [1] 294228 0
after five minutes of resting in the left lateral position and after five minutes of resting in the prone position
Secondary outcome [1] 312831 0
heart rate measured by an ECG in the left lateral and in the prone position
Timepoint [1] 312831 0
after five minutes of resting in the left lateral and in the prone position
Secondary outcome [2] 312832 0
respiratory rate, measured by an investigator counting the respiratory rate, in the left lateral and in the prone position
Timepoint [2] 312832 0
after five minutes of resting in the left lateral and in the prone position
Secondary outcome [3] 312833 0
cardiac output obtained by echocardiography in the left lateral and in the prone position
Timepoint [3] 312833 0
after five minutes of resting in the left lateral and in the prone position
Secondary outcome [4] 312909 0
Oxygen saturation, as measured by a pulse oximeter placed on the finger, after resting in the left lateral and in the prone position
Timepoint [4] 312909 0
after resting in the left lateral and in the prone position for five minutes

Eligibility
Key inclusion criteria
Healthy pregnant women:
Healthy term (greater than or equal to 37 weeks gestation) pregnant women will be defined as American Society of Anesthesiologists (ASA) Classification I or II, with no significant medical or surgical illness. Age 18-45 years
Women with gestationally acquired hypertension greater than or equal to 20 weeks gestation:
Women aged 18-45 years will be included in the study if they meet the diagnostic criteria for either gestational hypertension or preeclampsia.
Minimum age
18 Years
Maximum age
45 Years
Sex
Females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Healthy pregnant women:
current vasoactive medication including salbutamol and thyroxine, pre-existing or gestational diabetes, known cardiovascular disease including chronic disorders that may influence the cardiovascular system such as chronic renal disease, multiple pregnancy, smokers, any woman in labour or postpartum and inability to consent to study. Age < 18, > 45 years
Women with gestationally acquired hypertension:
Any woman with pre-existing or gestational diabetes, multiple pregnancy, smokers, any woman in labour, any woman with decompensated disease (eclampsia, pulmonary oedema) or postpartum and inability to consent to study, Age < 18, > 45 years

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
All enrolled women will receive the same treatment.
Recruitment of healthy pregnant women:
It is anticipated that most healthy term pregnant women will be recruited from the elective caesarean section operating list. Once a term healthy pregnant woman has been identified the investigator will assess whether the woman is eligible to participate in the study. If she is eligible to participate, the investigator will speak to the woman privately and ask her if she is willing to be involved in the study. Written information in the form of the participant information and consent form will be given to her. The study will be performed in a private room.

The recruitment of women with preeclampsia or gestational hypertension:
This will occur throughout the hospital. This will include the emergency department, day admission/assessment area, pregnancy clinics, hospital wards and birthing suite. The investigator will visit these areas of the hospital to check whether a woman with hypertension has presented there. Once a woman with hypertension has been identified the investigator they will assess whether the woman with hypertension is eligible to participate in the study (see exclusion /inclusion criteria). If she is eligible to participate, the AI will speak to the woman privately and ask her if she is willing to be involved in the study. Written information in the form of the participant information and consent form will be given to her. Most of these women will be in a hospital bed or private assessment area and so will not need to be moved to another location to discuss the study. After consent, if the woman is not already in a private room, she will be moved to a private room with a bed and undertake the study.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
This is a nonrandomised study
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Single group
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Rationale for the sample size:
The primary comparison measurement is blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) before and after being placed in the prone position. We have published our preliminary study that determined the mean and standard deviation of SBP (119 +/- 13.0 mmHg) and DBP (72 +/- 11.6 mmHg) in healthy term pregnant women and the mean and standard deviation of SBP (147 +/- 7.8 mmHg) and DBP (93 +/- 6.5 mmHg) in women with preeclampsia. For this study, assuming a clinically relevant difference in mean blood pressure, with the change in posture from the lateral position to the prone position, of 10 mmHg, and a power of 80% and a 5% type 1 risk, using a two tailed test, the following numbers are required in each group:
1. Healthy term pregnant women – 28 women (for a 10 mmHg difference in SBP) 23 women (for a 10 mmHg difference in DBP)
2. Hypertensive women - 11 women (for a 10 mmHg difference in SBP) 8 women (for a 10 mmHg difference in DBP)

In coming to the final study numbers we have made three assumptions:
1. Given that the definition of hypertension in pregnancy treats the SBP and DBP as independent i.e. the definition is Systolic blood pressure (SBP) greater than or equal to 140 mmHg And/or Diastolic blood pressure (DBP) greater than or equal to 90 mmHg we have not used correlated means.
2. The standard deviations in this study may be different from the original study so we have increased study numbers to accommodation this
3. Regarding the decision to choose a 10 mmHg mean blood pressure difference, given that the intervention to possibly reduce the blood pressure is a physiological one, it is unlikely, within the five minute time frame, that the blood pressure drop would be greater than 10 mmHg, however any less of a reduction than 10 mmHg is unlikely to be clinically relevant. A blood pressure reduction of 10 mmHg is clinically relevant as it may reduce the blood pressure to a threshold where treatment may not be necessary or the diagnostic threshold for the diagnosis is not met (if SBP/DBP greater than or equal to 140/90 mmHg). In addition we have found that healthy pregnant women have found the prone position comfortable and we would like to assess the preferred resting position in more women than is needed for the pure comparison statistic. Women with pre-eclampsia have also found the prone position comfortable and the data suggest that systolic blood pressure is reduced in the prone position. In order to explore this relationship further we have increased the sample size in women with pre-eclampsia.

Therefore total study numbers:
1. 100 healthy term pregnant women
2. 50 hypertensive pregnant women


Data collected:
Demographic and obstetric data will be displayed as mean and standard deviation, median with interquartile ranges, or number and percentage as appropriate. Analysis of the blood pressure, heart rate, respiratory rate and oxygen levels (using pulse oximetry) will be made using a General Linear Model with significant p value defined as less than 0.05 after performing F tests on the collected data. The null hypothesis will be rejected if p less than 0.05 for each of the variables. All analyses will be performed using Stata/MP 13.1 (Stata Software Inc.,Chicago IL).

Additional participant numbers: Healthy pregnant women have found the prone position comfortable and we would like to assess preferred position in more women so have increased the sample size to a convenience sample of 50 women in total in the healthy pregnancy group

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
3/03/2015
Actual
3/03/2015
Date of last participant enrolment
Anticipated
30/06/2022
Actual
18/11/2015
Date of last data collection
Anticipated
30/06/2023
Actual
20/10/2018
Sample size
Target
150
Accrual to date
Final
65
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 3422 0
The Royal Women's Hospital - Parkville
Recruitment postcode(s) [1] 9190 0
3052 - Parkville

Funding & Sponsors
Funding source category [1] 290693 0
Hospital
Name [1] 290693 0
The Royal Women's Hospital
Country [1] 290693 0
Australia
Funding source category [2] 290726 0
University
Name [2] 290726 0
The University of Melbourne
Country [2] 290726 0
Australia
Primary sponsor type
Hospital
Name
The Royal Womens Hospital Parkville
Address
Locked bag 300, Corner Flemington Road and Grattan Street, Parkville, Victoria, Australia 3052
Country
Australia
Secondary sponsor category [1] 289386 0
None
Name [1] 289386 0
Address [1] 289386 0
Country [1] 289386 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 292331 0
The Royal Women's Hospital Research and Human Research Ethics Committee
Ethics committee address [1] 292331 0
Locked Bag 300, Corner Flemington Road and Grattan Street, Parkville, Victoria, Australia 3052
Ethics committee country [1] 292331 0
Australia
Date submitted for ethics approval [1] 292331 0
Approval date [1] 292331 0
19/12/2012
Ethics approval number [1] 292331 0
Project 14/41

Summary
Brief summary
The prone position is a body position in which a person lies horizontal with the chest down and back up. With appropriate pillows and positioning, it is a safe position for pregnant women and because of this the position is utilised in the allied health fields and for relaxation and massage in pregnant women. In this position uterine compression of the large maternal vessels is alleviated. Yet, despite this, the prone position is rarely used in the medical setting in pregnant women and there is very little information about the position in the medical literature. There is no published information about the prone position in women with hypertension in pregnancy including preeclampsia.

We have recently published a new unified theory of preeclampsia. It proposes that the development of hypertension in pregnant women is an adaptive response to the demands of a growing fetus and is driven by an imbalance between maternal oxygen supply to the fetus (which may be caused by inadequate blood flow to the uteroplacental unit) and fetal oxygen demands.

When thinking about the prone position in the light of this new theory we hypothesise that placing a pregnant women, with new onset pregnancy associated hypertension, into this position may reduce her blood pressure by eliminating abdominal compression of blood vessels thereby reducing abdominal vascular resistance and improving blood flow.

This proposed study aims to test this hypothesis.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 53854 0
A/Prof Alicia T Dennis
Address 53854 0
Department of Anaesthesia, The Royal Women's Hospital, Locked Bag 300, Corner Flemington Road and Grattan Street, Parkville, Victoria, Australia 3052
Country 53854 0
Australia
Phone 53854 0
+61 3 8345 2000
Fax 53854 0
+61 3 8345 2379
Email 53854 0
[email protected]
Contact person for public queries
Name 53855 0
Alicia T Dennis
Address 53855 0
Department of Anaesthesia, The Royal Women's Hospital, Locked Bag 300, Corner Flemington Road and Grattan Street, Parkville, Victoria, Australia 3052
Country 53855 0
Australia
Phone 53855 0
+61 3 8345 2000
Fax 53855 0
Email 53855 0
[email protected]
Contact person for scientific queries
Name 53856 0
Alicia T Dennis
Address 53856 0
Department of Anaesthesia, The Royal Women's Hospital, Locked Bag 300, Corner Flemington Road and Grattan Street, Parkville, Victoria, Australia 3052
Country 53856 0
Australia
Phone 53856 0
+61 3 8345 2000
Fax 53856 0
Email 53856 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Identifiable data will not be available.



What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
TypeIs Peer Reviewed?DOICitations or Other DetailsAttachment
Study results articleYes Dennis AT, Hardy L, Leeton L. The prone position i... [More Details]
Plain language summaryNo This study revealed that the prone position is a c... [More Details]

Documents added automatically
SourceTitleYear of PublicationDOI
EmbaseThe prone position in healthy pregnant women and in women with preeclampsia - A pilot study.2018https://dx.doi.org/10.1186/s12884-018-2073-x
N.B. These documents automatically identified may not have been verified by the study sponsor.