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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
A multi-centre prospective observational study of simultaneous pulse oximeter and arterial oxygen saturation recordings in Intensive Care Unit patients.
Scientific title
In Intensive Care Unit patients requiring an arterial blood gas, a comparison between arterial oxygen saturation and pulse oximetry saturation measurements.
Secondary ID [1] 285878 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Any condition requiring measurement of arterial blood gas in the Intensive Care Unit 293799 0
Condition category
Condition code
Respiratory 294102 294102 0 0
Other respiratory disorders / diseases

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
Evaluation of simultaneous pulse oximetry (SpO2) and arterial blood gas (ABG) measured oxygen saturation (SaO2) values recorded in ICU patients.

The paired SpO2 value will be recorded at least 2 hours after admission to ICU, to allow for adjustments in oxygen therapy to become in-line with standard ICU practice for oxygen administration. Where possible, paired measurements will be done during the earliest arterial blood gas (ABG) taken after at least 2 hours of admission.

A single set of paired measurements will be taken per patient.
Intervention code [1] 290859 0
Not applicable
Comparator / control treatment
The SpO2 value recorded by the pulse oximeter will be paired with the ABG measured oxygen saturation (SaO2) value for comparison.
Control group

Primary outcome [1] 293894 0
SpO2, measured by pulse oximetry at the same time an ABG is performed.
Timepoint [1] 293894 0
The SpO2 value will be the first value displayed by the pulse oximeter following visualisation of blood entering the collection vial for the ABG analysis.
Primary outcome [2] 293895 0
SaO2, measured by ABG (while the pulse oximeter is in place).
ABG is assessed by means of a blood sample taken from an artery.
Timepoint [2] 293895 0
Taken at time of the clinically indicated ABG.
Secondary outcome [1] 312105 0
Timepoint [1] 312105 0

Key inclusion criteria
Four hundred patients with routine oxygen saturation monitoring and routine ABG measurements as part of their clinical care at Wellington Regional Hospital and Austin Hospital ICUs.
Minimum age
16 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Diagnosis of methaemoglobinemia or prior use of intravenous dye during this admission(e.g. methylene blue).
2. Diagnosis of CO poisoning.
3. Age under 16 years.
4. Patients previously recruited to the study with paired SpO2 and SaO2 values successfully recorded.
5. Any other condition which, at the investigator’s discretion, is believed may present a safety risk or impact upon the feasibility of the study or the interpretation of the study results.

Study design
Natural history
Defined population
Statistical methods / analysis

1. To describe the agreement between paired SpO2 and SaO2 measurements in terms of bias and limits of agreement.
2. To estimate the influence on bias of the paired SpO2 and SaO2 measurements by:
a. The mean oxygen saturation (average of SpO2 and SaO2)
b. PaCO2
c. APACHE II score (> 25 vs <25)
d. Inotrope administration at the time of ABG sample (yes or no)
e. Vasopressor administration at the time of ABG sample (yes or no)
f. Values immediately prior to ABG sample:
i. Capillary refill (<3 seconds vs >3 seconds)
ii. Last recorded axillary body temperature
iii. Temperature of hands (warm vs cool to touch)
iv. Mean arterial blood pressure
v. Pulse pressure
vi. Identification of any local factor by the nursing staff as potentially impacting on oximetry probe recording (e.g. motion artefact)
g. Skin pigmentation (based on modified Fitzpatrick scale with patient skin colour classified as either: Light (Type I to Type II), Medium (Type III to Type IV) or Dark (Type V to Type VI))
h. Pulse oximeter model (Philips IntelliVue MP70 or Mossimo TRAM-RAC 4A)
3. To describe the diagnostic performance of SpO2 to detect clinically important boundaries of SaO2 (90 %) and arterial oxygen tension (PaO2) (60 mmHg).

Objective 1: Bland-Altman plots and estimation of bias and limits of agreement.
Objective 2: Analysis of Covariance. Should important predictors of bias be identified Bland-Altman methods will be used to determine whether there is also an effect on limits of agreement.
Objective 3: Receiver Operating Characteristic curve estimation by logistic regression and associated prediction equations.

The planned sample size is based on three considerations. Firstly, for the analysis of variables that predict the size of the bias we seek to have between 20 and 40 participants for each degree of freedom in the ANCOVA. Based on the thirteen variables, some of which have multiple levels, this requires between 200 and 400 participants. Secondly, the estimates of paired SD for the SpO2 to SaO2 difference from the papers of Pu, Van de Leow and Wouters; were 0.55%, 2.1%, and 2.2% respectively. We wish to detect a SpO2 to SaO2 difference of 2% for any of the variables that might predict bias. If there were two equal sized groups of 42 participants, 21 in each group, there is 80% power, with a type I error rate of 5%, to detect this size difference. This suggests that a minimum of 20 participants with a particular characteristic will provide greater than 80% power to detect a difference of 2% between groups for dichotomous variables (because the complement of a particular characteristic will have be more numerous than 20). We consider a sample size of 400 as being likely that each individual characteristic will have at least 20 participants.

Recruitment status
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] 3291 0
Austin Health - Austin Hospital - Heidelberg
Recruitment outside Australia
Country [1] 6560 0
New Zealand
State/province [1] 6560 0

Funding & Sponsors
Funding source category [1] 290460 0
Name [1] 290460 0
Medical Research Institute of New Zealand
Address [1] 290460 0
Wellington Regional Hospital,
Riddiford Street,
Wellington 6021
Country [1] 290460 0
New Zealand
Primary sponsor type
Wellington Regional Hospital,
Riddiford Street,
Wellington 6021
New Zealand
Secondary sponsor category [1] 289162 0
Name [1] 289162 0
Address [1] 289162 0
Country [1] 289162 0
Other collaborator category [1] 278271 0
Name [1] 278271 0
Dr Michael Richards
Address [1] 278271 0
Wellington Regional Hospital,
Riddiford Street,
Wellington 6021
Country [1] 278271 0
New Zealand

Ethics approval
Ethics application status
Ethics committee name [1] 292133 0
Northern A Health and Disability Ethics Committee
Ethics committee address [1] 292133 0
Health and Disability Ethics Committees
Ministry of Health
C/- MEDSAFE, Level 6, Deloitte House
10 Brandon Street
PO Box 5013
Ethics committee country [1] 292133 0
New Zealand
Date submitted for ethics approval [1] 292133 0
Approval date [1] 292133 0
Ethics approval number [1] 292133 0

Brief summary
Pulse oximetry is commonly used in the clinical setting to guide oxygen therapy
The purpose of this study is to investigate the level of agreement between pulse oximeter measured oxygen saturations and arterial blood gas measured oxygen saturations (the gold standard for oxygen saturation measurement) in Australian and New Zealand Intensive Care Units.
Trial website
Trial related presentations / publications
Ebmeier, S. J., et al. "A two centre observational study of simultaneous pulse oximetry and arterial oxygen saturation recordings in intensive care unit patients." Anaesthesia & Intensive Care 46.3 (2018).
Public notes

Principal investigator
Name 53666 0
Dr Janine Pilcher
Address 53666 0
MRINZ, Wellington Regional Hospital, Riddiford Street, Newtown, Wellington 6021
Country 53666 0
New Zealand
Phone 53666 0
+64 4 8050241
Fax 53666 0
+64 4 3895707
Email 53666 0
Contact person for public queries
Name 53667 0
Dr Janine Pilcher
Address 53667 0
MRINZ, Wellington Regional Hospital, Riddiford Street, Newtown, Wellington 6021
Country 53667 0
New Zealand
Phone 53667 0
+64 4 8050241
Fax 53667 0
+64 4 3895707
Email 53667 0
Contact person for scientific queries
Name 53668 0
Dr Janine Pilcher
Address 53668 0
MRINZ, Wellington Regional Hospital, Riddiford Street, Newtown, Wellington 6021
Country 53668 0
New Zealand
Phone 53668 0
+64 4 8050241
Fax 53668 0
+64 4 3895707
Email 53668 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary