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Trial registered on ANZCTR

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

Titles & IDs
Public title
SurgicalPleth Index for the prediction of acute postoperative pain
Scientific title
SurgicalPleth Index for the prediction of acute postoperative pain
Secondary ID [1] 293142 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
postoperative pain 305115 0
Condition category
Condition code
Anaesthesiology 304436 304436 0 0
Pain management

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
Surgical Pleth Index will be recorded intraoperatively in 200 patients anaesthetized with sevoflurane/opioid during the last 5 minutes of an operation, just before the anaesthetic is lightened. Thereafter, postoperative pain will be recorded 3 times (for 15 minutes post recovery room admission) in the revcovery room (on a 0-10 numeric rating scale).
Intervention code [1] 299393 0
Not applicable
Comparator / control treatment
Control group

Primary outcome [1] 303675 0
Prospectively test the hypothesis that a SPI > 30 at the end of surgery may predict moderate-severe (pain >3 on 0-10 numeric rating scale) postoperative pain.
Timepoint [1] 303675 0
Within the first 15 minutes after recovery room admission.
Secondary outcome [1] 339835 0
To investigate the correlation between age and the predictive probability of SPI (for the prediction of postoperative pain in the recovery room)
Timepoint [1] 339835 0
pain measure within 15 minutes after recovery room admission

Key inclusion criteria
Patients aged 18-100 yrs. scheduled for anaesthesia (non emergency) with sevoflurane/opioid.
Minimum age
18 Years
Maximum age
100 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Regular or intraoperative medication (prior to SPI assessment) known or suspected to interact with the assessment of SPI (i.e. ketamine, clonidine, neostigmine, beta-receptor blockers, incl. metaraminol/ephedrine within 10 minutes of the SPI assessment), pacemaker, severe autonomous dysfunction, significant cardiac arrhythmia (i.e. AF), Aboriginal patients, patients with an impaired ability to rate their level of postoperative pain on a NRS (i.e. significant mental impairment, dementia), surgical tourniquet at the time of and/or < 10 minutes prior to SPI assessment, any analgesic medication between SPI assessment and first pain score in the recovery room (note: extremely rare)

Study design
Natural history
Convenience sample
Statistical methods / analysis
All data will be tested for normal distribution (KS test). Data may be described as mean (standard deviation)/median percentiles, as appropriate. For the assessment of SPI prediction of pain the analysis of the receiver operating characteristics (ROC) will be used. In addition, the predictive probability of the SPI cut-off (30) will be calculated via the excel macro PK MACRO (by Warren D. Smith). The differences between PK values for different age groups/anaesthetic techniques will be calculated via the macro PKD. The influence of age will be calculated via a linear regression model.

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] 9198 0
Royal Perth Hospital - Perth
Recruitment hospital [2] 9199 0
Armadale Kelmscott Memorial Hospital - Armadale
Recruitment postcode(s) [1] 17851 0
6000 - Perth
Recruitment postcode(s) [2] 17852 0
6112 - Armadale

Funding & Sponsors
Funding source category [1] 297770 0
Government body
Name [1] 297770 0
East Metropolitan Health Service
Address [1] 297770 0
02-118 Murdoch Dr, Murdoch WA 6150
Country [1] 297770 0
Primary sponsor type
Thomas Ledowski
Anaesthesiology Unit
University of Western Australia
35 Stirling Hwy
Crawley, WA
Secondary sponsor category [1] 296807 0
Name [1] 296807 0
Address [1] 296807 0
Country [1] 296807 0

Ethics approval
Ethics application status
Ethics committee name [1] 298831 0
Ethics Committee of the South Metro Health Service
Ethics committee address [1] 298831 0
1 Robin Warren Drive
Murdoch, WA 6150
Ethics committee country [1] 298831 0
Date submitted for ethics approval [1] 298831 0
Approval date [1] 298831 0
Ethics approval number [1] 298831 0

Brief summary
Background: The surgical pleth index (SPI, GE Healthcare, Helsinki, Finland) is a 0-100 score derived from the intraoperative non-invasive monitoring of oxygen saturation. Simply speaking, SPI is a software using existing data. The SPI score claims to reflect states of intraoperative pain. A previous investigation by us published in the British Journal of Anaesthesia (Br J Anaesth. 2016 Sep;117(3):371-4) found that a SPI > 30 at the end of surgery (prior to awakening) predicted moderate-severe postoperative pain.
Objectives: As such prediction would provide a significant benefit for the pre-emptive treatment of pain, the proposed project aims to prospectively validate the SPI cut-off published by us in a larger cohort. In addition, we would like to evaluate the influence of age on the SPI cut-off value predicting moderate-severe pain, as well as the influence of a different anaesthetic technique (total intravenous anaesthesia) on the predictive value of SPI. The latter sub-group will be investigated by our collaborators in Kiel, Germany.
Within WA Health 200 patients scheduled for non-emergency surgery under sevoflurane/opioid anaesthesia will be included in the study. Patients will receive a completely standard anaesthetic.
At the end of surgery, SPI will be recorded minutely for 5 minutes. As outlined above, this simply requires recording of displayed SPI values. As SPI uses available data derived from standard monitoring, no discomfort or risk is associated with study inclusion. After awakening, 3 pain scores (numeric rating scales 0-10) will be recorded in the recovery room. The 5-minutely recording of pain scores is standard protocol in the involved hospitals and does hence not at all inconvenience patients. Apart from SPI and pain readings, only very limited data are recorded.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 78370 0
Prof Thomas Ledowski
Address 78370 0
Medical School
University of Western Australia
35 Stirling Hwy
Crawley WA 6009
Country 78370 0
Phone 78370 0
+61 8 9224 0210
Fax 78370 0
Email 78370 0
Contact person for public queries
Name 78371 0
Prof Thomas Ledowski
Address 78371 0
Medical School
University of Western Australia
35 Stirling Hwy
Crawley WA 6009
Country 78371 0
Phone 78371 0
+61 8 9224 0210
Fax 78371 0
Email 78371 0
Contact person for scientific queries
Name 78372 0
Prof Thomas Ledowski
Address 78372 0
Medical School
University of Western Australia
35 Stirling Hwy
Crawley WA 6009
Country 78372 0
Phone 78372 0
+61 8 9224 0210
Fax 78372 0
Email 78372 0

No information has been provided regarding IPD availability
Summary results
No Results