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Trial registered on ANZCTR


Registration number
ACTRN12622000559718
Ethics application status
Approved
Date submitted
21/03/2022
Date registered
12/04/2022
Date last updated
30/01/2023
Date data sharing statement initially provided
12/04/2022
Date results information initially provided
30/01/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Does the position of the surgical bed affect paediatric patients in terms of perioperative respiratory adverse events?
Scientific title
Impact of patient positioning around surgery on the occurrence of perioperative respiratory adverse events – analysing a change in routine management in children undergoing general anaesthesia– POSSUM
Secondary ID [1] 306732 0
Nil known
Universal Trial Number (UTN)
Nil known
Trial acronym
POSSUM
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Perioperative Respiratory Adverse Events 325718 0
Condition category
Condition code
Anaesthesiology 323063 323063 0 0
Anaesthetics
Surgery 323064 323064 0 0
Other surgery

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This trial compares the incidence of perioperative respiratory adverse events between children with inclined head position (30 degrees) and those laid flat on their surgical bed from (1) induction and transfer to theatre and (2) from transfer at the end of surgery to trolley, to the post operative care unit (PACU), and until fully awake in PACU.

To clarify the intervention is the position of the surgical bed - either flat or at an angle of 30 degrees.
The timing of the intervention will be variable and totally depend each participant's anaesthesia experience. The length of time for the induction of anaesthesia and on the end of surgery and transfer to recovery will vary from patient to patient but is anticipated to be 10 to 45 minutes for induction of anaesthesia and for the end of surgery it is anticipated to be 20-60 minutes.
The mechanical settings on the surgical beds will be used to achieve the angle required for the study.
A case report form (CRF) will be completed for each patient and the anaesthetists will need to document if the intervention was adhered to or not.
The surgical head position will be at the discretion of the anaesthetist in conjunction with the surgeon.
Intervention code [1] 323174 0
Prevention
Intervention code [2] 323290 0
Treatment: Other
Comparator / control treatment
Comparator is the flat position of the surgical bed during the induction of anaesthesia and transfer of the patient from the induction bay to the operating theatre and also at the end of surgery the transfer of the patient from the surgical bed to the post operative care unit bed until patient is fully awake.
Control group
Active

Outcomes
Primary outcome [1] 330828 0
To investigate the difference in the incidence of perioperative respiratory adverse events (PRAE) in patients undergoing general anaesthesia who will undergo different head positions, lying flat, inclined at 30 degrees or positioning chosen by anaesthetist and Post Anaesthesia Care Unit (PACU) nurses.

All patients will have a case report form (CRF) completed with details of any perioperative respiratory adverse events recorded as well as other demographics and anaesthesia management information.

PRAE are defined as:
Laryngospasm: complete airway obstruction with associated muscle rigidity of the abdominal and chest walls. Bronchospasm: increased respiratory effort, particularly during expiration and wheeze on auscultation.
Desaturation: Oxygen saturation < 95%>10secs on pulse oximetry, with a significant defined as desaturation <90% >10 secs
Airway obstruction: the presence of airway obstruction with a snoring noise and/or increased respiratory efforts.
Severe persistent coughing: pronounced, persistent coughs lasting more than 10 seconds.
Post-operative stridor: high pitched sound during breathing in the postoperative period.
Timepoint [1] 330828 0
Perioperative respiratory adverse events (PRAE) will be recorded during induction, maintenance, emergence and recovery of anaesthesia.
Secondary outcome [1] 407754 0
Satisfaction of clinical staff (anaesthetist, anaesthetic technician, surgeon, PACU/recovery nurse) with allocated head position.
All patients will have a case report form (CRF) completed with this information added.
Timepoint [1] 407754 0
Recorded at the end of every case.
Secondary outcome [2] 407755 0
Difference in perioperative respiratory adverse events (PRAE) incidence expected by anaesthetists, nurses (theatre and PACU) and anaesthetic technicians for each position

This will be documented prior to the start of the study intervention on a study survey.
Timepoint [2] 407755 0
This will be recorded prior to the recruitment of patients. All staff will be questioned and their results documented on a study survey.
Secondary outcome [3] 407756 0
Difference in perioperative respiratory adverse events (PRAE) incidence which would see a change in practice by anaesthetists, nurses (theatre and PACU) and anaesthetic technicians.

This will be documented prior to the start of the study intervention on a study survey.
Timepoint [3] 407756 0
This will be recorded prior to the recruitment of patients. All staff will be questioned and their results documented.

Eligibility
Key inclusion criteria
All children undergoing elective and emergency surgery under general anaesthesia in the operating theatres at Perth Children's Hospital who will be transferred to the post operative care unit (PACU) after surgery – between 8am and 6pm on weekdays.
Minimum age
0 Years
Maximum age
18 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
The following will be excluded from participation:
Patients who have an inability to tolerate being flat pre-operatively e.g. heart failure/ aspiration risk etc., at the discretion of the treating anaesthetist
Patients transferred from theatre straight to PICU or NICU

Study design
Purpose of the study
Prevention
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
To minimise bias in cross sectional studies we will include participants over a 12 week-period, with all children in each one-week period (8am to 6pm each day Monday to Friday) for the first 8 weeks being assigned one of the head positions (supine/flat or 30 degree inclined). The positioning for the final four weeks will be at the discretion of the treating anaesthetist or PACU nurse. The surgical lists in our institution operate on four-week cycles with some surgical specialities scheduled for one list a fortnight or one list every four weeks and others having multiple lists per week. In order to ensure that all specialities and therefore all types of surgeries are included equally between the group allocations we will enrol patients over 12 weeks with 4 weeks of supine/flat or 30 degree inclined, and 4 weeks of anaesthetist and nurse own preference. If surgery activity is significantly reduced or limitations are placed on research studies, these weeks may not necessarily be consecutive, or a second 12-week period might be necessary. However, we will include all 4 weeks (week A, B, C, D) of patients from each surgery cycle. For example, children in weeks 1, 3, 6 and 8 of the study will be in a flat head position while those in weeks 2, 4, 5 and 7 of the study will be in an inclined head position. Children from weeks 9-12 will be positioned at the discretion of the treating anaesthetist or PACU nurse. By alternating the groups in this way, we will account for differing speciality surgical lists over the fortnightly cycles of theatre bookings. All patients entering the PACU will be included into this study.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Safety
Statistical methods / analysis
The differences between the flat and 30-degree groups will be analysed as a two-level clustered Poisson log-linear model (generalised linear model), with the number of PRAE as the response variable, cluster (week) as the random factor, and one of two treatment levels (either 30-degree position or lying flat) applied to each week. The number of patients per week is expected to be different; differences between weeks will be modelled by a random intercept term in the model. Demographic and other clinical variables will be entered as covariates. A zero-inflated Poisson model will be considered if the data shows a larger proportion of zeroes. Alternatively, if the Poisson model exhibits over-dispersion then a negative binomial model will be considered. The incidence of PRAE in the free choice week will similarly be compared to the randomised weeks in a second analysis.

Variables for statistical modelling
The main variables that will be recorded and included in the statistical modelling are sex, age, height, weight, type of surgery, head position, URTI in the last two weeks, snoring and obstructive sleep apnoea, recurrent wheeze/asthma and anaesthetic management.
Large amounts of missing data are not expected, since data will be collected by an experienced research team at PCH; as such, primary analysis will consider only available data with no imputation. In the event of a high proportion of missing data for the primary outcome, imputation using a standard technique will be considered.
All statistical analysis will be conducted in the R statistical environment

Sample Size
Sample size and power calculations for a complex design such as this is based on simulations. Our main interest is in comparison of the flat and 30-degree inclined positions, which occur during the first 8 weeks of the study. In the last 4 weeks the positions are determined by staff preference. Thus, we will restrict our sample size calculation to the designed 8-week period only. The between-cluster variance is the variance between (the four) clusters within the same treatment level in the first 8 weeks of the study. In our study the clusters can be assumed to be uniform with little variation between them. We set a between-cluster variance of 0.1 (standard deviation 0.3), assumed to be equal for each treatment level. Further, the mean PRAE rate is set to 1 for the inclined group and 2 for the flat group. With these settings a sample size of 200 gives a power of 90%. If we increase the between-cluster variance to 0.15 (standard deviation 0.39) the power reduces 77%. The estimated mean differences between the two head positions is 0.7. As discussed previously, a sample size of 200 per cluster (week) is conservative and achievable.

All children undergoing elective and emergency surgery under anaesthesia in the operating theatres who will be sent to PACU after surgery. Enrolment will take place over 12 weeks with all the children in a one-week period over the first 8 weeks being assigned one of the head positions. Weeks 1, 3, 6 and 8 of the study will be assigned a one position and all children in weeks 2, 4, 5 and 7 of the study will be assigned the other head position. Weeks 9 to 12 will include all children with the choice of the head position being left to the decision of the anaesthetists and the nursing staff. By alternating the groups in this way, we will account for differing surgical lists over the fortnightly cycles of theatre bookings. At PCH 17,000 children undergo surgery annually. Allowing for those that go to ICU after surgery we expect to collect data of 2400 to 3000 children over the 12 weeks. If surgery is slowed or stopped e.g. due to COVID restrictions such that the minimum number of 1600 (200 per week for the 8 weeks of randomisation) is not enrolled, then the data collection period of 12 weeks will be repeated.

Study Significance
The level of significance to be used will be 0.05.

Selection of participants for analyses:
All evaluable participants will be included in the analyses.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
3/10/2022
Actual
3/10/2022
Date of last participant enrolment
Anticipated
31/03/2023
Actual
23/12/2022
Date of last data collection
Anticipated
31/03/2023
Actual
23/12/2022
Sample size
Target
2000
Accrual to date
Final
2851
Recruitment in Australia
Recruitment state(s)
WA
Recruitment hospital [1] 21998 0
Perth Children's Hospital - Nedlands
Recruitment postcode(s) [1] 37100 0
6009 - Nedlands

Funding & Sponsors
Funding source category [1] 311063 0
Hospital
Name [1] 311063 0
Perth Children's Hospital
Country [1] 311063 0
Australia
Primary sponsor type
Hospital
Name
Perth Children's Hospital
Address
Perth Children's Hospital
15 Hospital Avenue
Nedlands
WA 6009
Country
Australia
Secondary sponsor category [1] 312395 0
None
Name [1] 312395 0
Address [1] 312395 0
Country [1] 312395 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 310608 0
Child and Adolescent Health Service Human Research Ethics Committee
Ethics committee address [1] 310608 0
Child and Adolescent Health Service Human Research Ethics Committee
15 Hospital Avenue
Nedlands
Western Australia 6009
Ethics committee country [1] 310608 0
Australia
Date submitted for ethics approval [1] 310608 0
15/02/2022
Approval date [1] 310608 0
17/03/2022
Ethics approval number [1] 310608 0
RGS0000005292

Summary
Brief summary
Perioperative respiratory adverse events (PRAE) are one of the major causes of morbidity and mortality during paediatric anaesthesia. Three quarters of critical incidents and at least one third of peri-operative cardiac arrests are linked to adverse respiratory events. Fortunately most perioperative respiratory adverse events are easily managed with no postoperative sequelae but some can lead to life threatening hypoxemia. Various definitions of perioperative respiratory adverse events are in use, but they are commonly considered to be any adverse event impacting the respiratory system at the induction of anaesthesia, intraoperatively or early post operatively. This includes laryngospasm, bronchospasm, hypopnea or apnea, breath holding, hypoxemia or the prolonged need for supplemental oxygen, pulmonary aspiration, airway obstruction, severe cough, stridor or reintubation. These events can adversely affect perioperative outcomes, including increased resource utilization and costs.
The induction of anaesthesia and the immediate post-operative periods are high risk times for PRAE. While multiple management strategies exist to prevent PRAE at these critical phases of patient care, there is a paucity of data on whether patient positioning on the surgical bed alters the incidence of PRAE.
In this study we will investigate if positioning the patient’s head elevated at a 30- degree incline for induction and transfer to the operating room and again from the end of surgery through to fully awake in post anaesthesia care unit (PACU) results in a lower incidence of PRAE in children, as compared to flat positioning (0 degrees) throughout this period. Both patient positions are commonly used in routine clinical practice in our institution both in theatre and in PACU. There are no guidelines or evidence specifying the use of one over the other.
Trial website
None
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 118250 0
Prof Britta Regli-von Ungern-Sternberg
Address 118250 0
Perth Children's Hospital
15 Hospital Avenue
Nedlands
WA 6009
Country 118250 0
Australia
Phone 118250 0
+61420790101
Fax 118250 0
Email 118250 0
Britta.Regli-VonUngern@health.wa.gov.au
Contact person for public queries
Name 118251 0
Prof Britta Regli-von Ungern-Sternberg
Address 118251 0
Perth Children's Hospital
15 Hospital Avenue
Nedlands
WA 6009
Country 118251 0
Australia
Phone 118251 0
+61420790101
Fax 118251 0
Email 118251 0
Britta.Regli-VonUngern@health.wa.gov.au
Contact person for scientific queries
Name 118252 0
Prof Britta Regli-von Ungern-Sternberg
Address 118252 0
Perth Children's Hospital
15 Hospital Avenue
Nedlands
WA 6009
Country 118252 0
Australia
Phone 118252 0
+61420790101
Fax 118252 0
Email 118252 0
Britta.Regli-VonUngern@health.wa.gov.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Team haven't decided on this process yet.


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.