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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Does utilisation of surgical humidification reduce surgical site infection in colorectal surgery patients? A randomised control trial
Scientific title
Does utilisation of surgical humidification reduce surgical site infection in colorectal surgery patients? A randomised control trial
Secondary ID [1] 300560 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Open colorectal surgery 316283 0
Wound infections 316284 0
Surgical site infections 316285 0
Condition category
Condition code
Surgery 314559 314559 0 0
Other surgery
Infection 314680 314680 0 0
Other infectious diseases

Study type
Description of intervention(s) / exposure
Brief name of intervention: HumiGard system

The investigational device to be used will be the Fisher and Paykel HumiGard™ Surgical Humidification System – see the user instruction provided with the humidifier (UI-185046315) during open colorectal surgery procedures (on the laparotomy wound).

The HumiGard system is a heat delivery system that allows insufflation of warm humidified CO2 into the open wound cavity. Dry medical CO2 is delivered at a flow rate of 10 L/min and a pressure of 4.5 bar from a medical pressurized gas cylinder via a ¼ inch (6.35 mm) PVC tube to an open surgery humidification system (F&P HumiGard™, Fisher & Paykel Healthcare Ltd, Auckland, New Zealand). It consists of a bacterial filter, and a humidification chamber filled with 180 ml sterile water, positioned on a humidifier controller that includes an integrated temperature and flow sensor. The outlet of the humidification chamber is connected to a thermally insulated 2.5 m long heated insufflation tube that maintains temperature and humidity of the gas to its outlet. The humidified and warm CO2 enters a gas diffuser (VITA-diffuser®, Cardia Innovation AB, Stockholm, Sweden) consisting of a 25 cm long PVC tube (inner diameter of 2.5mm) with polyurethane foam at its end. The cylindrical polyurethane foam tip diverts the gas jet into multiple directions via the many small paths inside the foam. The gas is thus uniformly distributed and the large diffuser surface area greatly reduces the velocity of the outflow.

Participants that are included will be randomly allocated, 1:1, to one of two groups (n = 149 per group); HumiGard™ (intervention) standard of care (no intervention) in elective and emergency open colorectal surgery cases.

The intervention will be delivered by surgeons and theatre staff (trained to use the device on open colorectal surgery laparotomy wounds) to patients in person, individually to each patient, during their open colorectal surgery procedure only, with the surgery performed in a hospital. It is a standardised intervention that will not be personalised, titrated or adapted to individuals or groups of individuals in the intervention arm. em intervention during their open colorectal surgery procedure (i.e. no additional treatment). Standard of care will be otherwise followed as routine at our institution for patients undergoing open colorectal surgery procedures.
Intervention code [1] 316862 0
Treatment: Devices
Comparator / control treatment
The comparator/control treatment group will not receive the HumiGard system intervention during their open colorectal surgery procedure (i.e. no additional treatment).
Control group

Primary outcome [1] 322883 0
Surgical site infection, assessed using the Classification of Surgical Site Infections from Onyekwelu et al. (2017) adapted from the CDC/NHSN Surveillance Definitions for Specific Types of Infections
Timepoint [1] 322883 0
Assessment of evidence of surgical site infection at 14 days and 30 days post-operatively
Secondary outcome [1] 380137 0
Time (in days) from admission to fitness for discharge from hospital; to be assessed using data-linkage to medical records
Timepoint [1] 380137 0
As documented by the medical team, noted at the time of event
Secondary outcome [2] 380138 0
Return to theatre for intervention of surgical site infection (such as debridement or washout), with surgical site infection; surgical site infection is assessed using the Classification of Surgical Site Infections from Onyekwelu et al. (2017) adapted from the CDC/NHSN Surveillance Definitions for Specific Types of Infections. This will be assessed via medical records and wound assessment as per clinician reports stated in medial records.
Timepoint [2] 380138 0
Time (in days) from original laparotomy operation to the date of return to theatre for further intervention; to be assessed using data-linkage to medical records, noted at the time of event
Secondary outcome [3] 380139 0
Need for antibiotic use to treat surgical site infection; to be assessed using data-linkage to medical records
Timepoint [3] 380139 0
Date of commencement and cessation of antibiotic therapy, and duration of treatment (in days required), noted at the time of event

Key inclusion criteria
1. Patients undergoing elective or emergency open colorectal resection
2. Able to give informed consent
Minimum age
18 Years
Maximum age
80 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Pregnancy
2. Terminal organ impairment
3. Patients that have to return to theatre for pathology unrelated to surgical wound site infection such as anastomotic leaks, revisions or re-look laparotomy washouts
4. Evidence, preoperatively, of any of the following: sepsis, severe sepsis, or septic shock
5. Contraindication for CO2
6. BMI > 40 as patients with morbid obesity will have higher mortality and SSI rates
7. Current abdominal wall infection/surgical site infection secondary to previous laparotomy/laparoscopy or from any other cause
8. History of laparotomy within the last 60 days
9. Immunological disease (e.g. HIV/AIDS)
10. Systemic steroid use or other immunosuppressant medication
11. ASA score greater than or equal to 4
12. Uncontrolled diabetes mellitus
13. Use of wound protection devices such as the Alexis port

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Separate randomisation will be put in place for the elective and emergency cases to account for selection bias. Given this is a single blinded trial, blinding will occur at the level of the patient. It is not practically feasible to blind surgeons from the intervention. No subjective outcomes are assessed by the surgeon so not being blinded will not introduce any bias. Participants will be blinded to their allocation. It is impossible to blind surgeons to the intervention/device, however post-operative assessment will occur by other investigators who are therefore blinded to the intervention.

Randomisation for the allocated group will occur after consent is obtained and after the patient’s eligibility is confirmed based on the inclusion and exclusion criteria. Patients deemed eligible for the study will have the primary surgeon draw an envelope that simply has ‘Humigard study’ written on it and inside will be a piece of paper that has either ‘control’ or ‘Humigard’. These will be prepared by the primary investigator before commencement of the study.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomised table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
A total of 298 subjects (n = 298) will be enrolled to participate in the study, with 149 subjects (n = 149) per treatment group. The study plan is for independent cases and controls with one control per case. The study period is 24 months depending on recruitment, since an average of 5-7 patients per week will undergo open elective or emergency colon resection surgery, and we expect a recruitment rate of >90% and a dropout rate of <5%.

The current SSI rate for open colorectal surgery at our centre is approximately 15%. To aim for a reduction down to 5%, which is the infection rate for all surgical site infections2, we calculate we will need to have 149 experimental and 149 control participants to reject the null hypothesis that the infection rate for the experimental versus control participants are equal with a probability (power) of 0.8. The type I error associated with this test of the null hypothesis was set at 0.05. This sample size calculation was based on an assumption that either the chi-squared or Fisher’s exact test will be used to evaluate the null hypothesis.35

All continuous variable data will be tested using the Shapiro Wilks test for normality, all data which have a normal distribution will be described using mean ± standard deviation. Data that is not normally distributed will be described with median and the intra-quartile range. Comparisons between groups, for example patients treated with standard of care versus HumiGard™ will be made by t-tests and analysis of variance (ANOVAs) for normally distributed data or the non-parametric equivalents Wilcoxon–Mann Whitney and Kruskal Wallis test for non-normally distributed data. Alternatively, we may use regression analysis (Generalised linear mixed models (GLMM) which can be used with non-normally distributed data.

Categorical data will be described as frequency (percentage) and compared using Fisher’s exact test or Chi squared test as appropriate. Investigation of what factors may statistically significantly modify or predict outcomes such as the patient’s recent medical history or their post-operative care will be investigated using regression analysis. The type of regression analysis will depend on the nature of the variables (whether continuous, interval or categorical, and their distribution) and how many independent and dependent variables are being compared (multivariate and/or multiple regression). Only 2-sides tests will be used, and p values of <0.05 deemed significant.

Secondary outcome:
The time patients are fit for discharge and temperature (core and local), will be compared by either t-test or Wilcoxon-Mann Whitney test for HumiGardTM versus standard of care. Further comparison such as difference within each treatment group according to for example medical history or demographic data or post-surgical care will use multiple regression or GLMM.

The frequency for return to theatre for SSI debridement or washout and antibiotic use will use chi squared or Fisher’s exact tests to compare between treatments (HumiGardTM versus standard of care). They may also be investigated by regression analysis to determine if they had statistically significant influence on the SSI incidence.

In general, data will be entered into an excel spreadsheet including identifying data to ensure accuracy of data entry at different time points. Following completion of data entry, data will be checked for any duplicates of data entry. The identifying data will be removed except for the Study ID number and then given to statistician for analysis. Where necessary, data will be for recoded for statistical analysis (e.g. females identified as 0 and males as 1) and imported into STATA v15 for statistical analysis.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 15890 0
Dandenong Hospital - Dandenong
Recruitment hospital [2] 15891 0
Monash Medical Centre - Clayton campus - Clayton
Recruitment postcode(s) [1] 29347 0
3175 - Dandenong
Recruitment postcode(s) [2] 29348 0
3168 - Clayton

Funding & Sponsors
Funding source category [1] 304978 0
Commercial sector/Industry
Name [1] 304978 0
Fisher and Paykel Ltd
Address [1] 304978 0
19-31 King Street, Nunawading VIC 3131
Country [1] 304978 0
Primary sponsor type
Mr Asiri Arachchi
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Secondary sponsor category [1] 305332 0
Name [1] 305332 0
Dandenong Hospital
Address [1] 305332 0
135 David Street, Dandenong VIC 3175
Country [1] 305332 0
Secondary sponsor category [2] 305333 0
Name [2] 305333 0
Monash Medical Centre
Address [2] 305333 0
246 Clayton Road, Clayton VIC 3168
Country [2] 305333 0
Other collaborator category [1] 281193 0
Name [1] 281193 0
Dr Alice Lee
Address [1] 281193 0
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Country [1] 281193 0
Other collaborator category [2] 281194 0
Name [2] 281194 0
Mr William Teoh
Address [2] 281194 0
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Country [2] 281194 0

Ethics approval
Ethics application status
Ethics committee name [1] 305381 0
Monash Health Human Research Ethics Committee
Ethics committee address [1] 305381 0
Research Support Services
Monash Health
Level 2, I Block
Monash Medical Centre
246 Clayton Road
Clayton VIC 3168
Ethics committee country [1] 305381 0
Date submitted for ethics approval [1] 305381 0
Approval date [1] 305381 0
Ethics approval number [1] 305381 0

Brief summary
Research Aims
To assess the efficacy of warm humidified carbon dioxide (CO2) insufflation to reduce surgical site infection in patients undergoing open colorectal surgery.

Adult participants undergoing open colorectal surgery at Dandenong Hospital who meet the inclusion and exclusion criteria.

Eligible participants will be randomised to receive standard of care or standard of care plus warm humidified carbon dioxide insufflation of the open wound during their scheduled open colorectal procedure. Insufflation will be provided with the HumiGard Surgical Humidification system, up to 10L of CO2 gas will be slowly insufflated into the surgical cavity for the duration of the operation. Participants will be blinded to their allocation.

Expected outcomes
Completing this project will allow us to determine whether warmed and humidified carbon dioxide gas can assist with reducing surgical site infections.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 100186 0
Mr Asiri Arachchi
Address 100186 0
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Country 100186 0
Phone 100186 0
+61 3 9554 1000
Fax 100186 0
Email 100186 0
Contact person for public queries
Name 100187 0
Mr Asiri Arachchi
Address 100187 0
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Country 100187 0
Phone 100187 0
+61 3 9554 1000
Fax 100187 0
Email 100187 0
Contact person for scientific queries
Name 100188 0
Mr Asiri Arachchi
Address 100188 0
Colorectal Surgery Unit, Dandenong Hospital, 135 David Street, Dandenong VIC 3175
Country 100188 0
Phone 100188 0
+61 3 9554 1000
Fax 100188 0
Email 100188 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Data will be stored by research investigators, data tabulated into a password protected and encrypted database, and paper form of the diary will then be shredded. This project stores patients, surgical, anaesthetic, and post-operative data in a de-identified format. We will not have de-identified individual participant data available.
What supporting documents are/will be available?
No other documents available
Summary results
No Results