Peri-operative Slow-paced Breathing - a Non-invasive Technique to Reduce Anxiety in Breast Cancer Surgery Patients
Phase: NA
Conditions: Anxiety
Sponsor: The Netherlands Cancer Institute

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RESEARCH PROTOCOL 
Peri-operative slow-paced breathing - a non-
invasive technique to reduce anxiety in breast 
cancer surgery patients 
Slow-PACE trial 
 
 
 
 

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Peri-operative slow-paced breathing - a non-invasive technique to reduce anxiety  
Slow PACE trial 
 
Protocol ID 
Slow PACE version 1.0 
Short title 
Slow PACE 
Version 
2.0  
Date 
04-09-2023 
Project leader 
 
Dr. Sabrine N.T. Hemmes 
Department of Anesthesiology 
Netherlands Cancer Institute – Antoni van 
Leeuwenhoek 
Plesmanlaan 121, 1066 CX Amsterdam 
T: +31 (0)20-5129111 
Email: s.hemmes@nki.nl 
Principal investigator 
Dr. Sabrine N.T. Hemmes 
Department of Anesthesiology 
Netherlands Cancer Institute – Antoni van 
Leeuwenhoek 
Plesmanlaan 121, 1066 CX Amsterdam 
T: +31 (0)20-5129111 
Email: s.hemmes@nki.nl 
Sponsor 
Antoni van Leeuwenhoek - Netherlands Cancer 
Institute 
Subsidising party 
N/A 
Independent expert 
Tina Eftyhmiou 
Antoni van Leeuwenhoek Ziekenhuis  
Department of Anesthesiology  
Plesmanlaan 121 1066 CX Amsterdam  
T: +31 (0)20-5121595  
Email: t.eftyhmiou@nki.nl 
Laboratory sites  
N/A 

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PROTOCOL SIGNATURE SHEET 
 
Name
Signature
Date
Sponsor or legal representative:
Department of Anesthesiology, Antoni van 
Leeuwenhoek, Netherlands Cancer 
Institute. 
 
Head of Department: 
Dr. L. Hulshoff 
 
 
 
Principal Investigator:
Dr. Sabrine N.T. Hemmes, PhD 
Department of Anesthesiology 
  
 
 
 
 

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Steering Committee of Slow PACE 
 
Steering Committee
Dr. Sabrine N.T. Hemmes 
Department of Anesthesiology 
NKI – AvL  
Email: s.hemmes@nki.nl 
Dr. Suzanne Broens 
Department of Anesthesiology 
NKI – AvL  
Email: s.broens@nki.nl 
Dr. Iris van der Ploeg 
Surgical Department 
NKI – AvL 
Email: i.vd.ploeg@nki.nl 
Anne Huisman 
Psychiatry department 
NKI – AvL 
Email: a.huisman@nki.nl 
Lenie Hulshoff 
Department of Anesthesiology 
NKI – AvL  
Email: l.hulshoff@nki.nl 
 

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TABLE OF CONTENTS 
 
1. 
INTRODUCTION AND RATIONALE .............................................................................. 9 
1.1 
Perioperative anxiety in breast cancer surgery patients ........................................... 9 
1.2 
Rationale ................................................................................................................. 9 
1.3 
Aim .......................................................................................................................... 9 
2. 
OBJECTIVES ................................................................................................................10 
2.1 
HYPOTHESIS ........................................................................................................10 
3. 
STUDY DESIGN ...........................................................................................................11 
4. 
STUDY POPULATION ..................................................................................................12 
4.1 
Population (base) ...................................................................................................12 
4.2 
Inclusion criteria .....................................................................................................12 
4.3 
Exclusion criteria ....................................................................................................12 
4.4 
Sample size calculation ..........................................................................................12 
5. 
TREATMENT OF SUBJECTS .......................................................................................14 
5.1 
Investigational treatment ........................................................................................14 
5.2 
Use of co-intervention ............................................................................................14 
6. 
INVESTIGATIONAL PRODUCT ....................................................................................14 
7. 
NON-INVESTIGATIONAL PRODUCT ...........................................................................14 
8. 
METHODS ....................................................................................................................15 
8.1 
Study parameters ...................................................................................................15 
8.1.1 
Main study parameter ......................................................................................15 
8.1.2 
Secondary study parameters ...........................................................................15 
8.1.3 
Other study parameters ...................................................................................15 
8.2 
Randomisation, blinding and treatment allocation ..................................................16 
8.3 
Study procedures ...................................................................................................17 
8.3.1 
General ...........................................................................................................17 
8.3.2 
Measures of anxiety ........................................................................................17 
8.3.3 
Slow PACE breathing ......................................................................................18 
8.3.4 
Other study procedures ...................................................................................19 
8.4 
Withdrawal of individual subjects ............................................................................20 
8.5 
Replacement of individual subjects after withdrawal ...............................................20 
8.6 
Follow-up of subjects withdrawn from treatment .....................................................20 
8.7 
Premature termination of the study .........................................................................20 
9. 
SAFETY REPORTING ..................................................................................................20 
9.1 
Temporary halt for reasons of subject safety ..........................................................20 
9.2 
AEs, SAEs and SUSARs ........................................................................................21 
9.2.1 
Adverse events (AEs) ......................................................................................21 
9.2.2 
Serious adverse events (SAEs) .......................................................................21 
9.2.3 
Suspected unexpected serious adverse reactions (SUSARs) .........................22 
9.3 
Annual safety report ...............................................................................................22 
9.4 
Follow-up of adverse events ...................................................................................22 
9.5 
Data Safety Monitoring Board (DSMB) ...................................................................22 

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10. 
STATISTICAL ANALYSIS ..........................................................................................23 
10.1 
Sample size calculation ..........................................................................................23 
10.2 
Analysis sets ..........................................................................................................23 
10.3 
Primary study parameter ........................................................................................23 
10.4 
Secondary study parameters ..................................................................................23 
10.5 
Other study parameters ..........................................................................................24 
10.6 
Interim analysis ......................................................................................................24 
11. 
ETHICAL CONSIDERATIONS ...................................................................................25 
11.1 
Regulation statement .............................................................................................25 
11.2 
Recruitment and consent........................................................................................25 
11.2.1 
Recruitment .....................................................................................................25 
11.2.2 
Consent ...........................................................................................................26 
11.3 
Objection by minors or incapacitated subjects ........................................................26 
11.4 
Benefits and risks assessment, group relatedness .................................................26 
11.5 
Compensation for injury .........................................................................................26 
11.6 
Incentives ...............................................................................................................26 
12. 
ADMINISTRATIVE ASPECTS, MONITORING AND PUBLICATION .........................27 
12.1 
Handling and storage of data and documents ........................................................27 
12.2 
Monitoring and Quality Assurance ..........................................................................27 
12.3 
Amendments ..........................................................................................................27 
12.4 
Annual progress report ...........................................................................................27 
12.5 
Temporary halt and (prematurely) end of study report ............................................27 
12.6 
Public disclosure and publication policy ..................................................................28 
13. 
STRUCTURED RISK ANALYSIS...............................................................................28 
14. 
REFERENCES ..........................................................................................................29 

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LIST OF ABBREVIATIONS AND RELEVANT DEFINITIONS  
 
ABR 
General Assessment and Registration form (ABR form), the application form that 
is required for submission to the accredited Ethics Committee; in Dutch: Algemeen 
Beoordelings- en Registratieformulier (ABR-formulier) 
AE 
Adverse Event 
CA 
Competent Authority 
CCMO 
Central Committee on Research Involving Human Subjects; in Dutch: Centrale 
Commissie Mensgebonden Onderzoek 
CV 
Curriculum Vitae 
DSMB 
Data Safety Monitoring Board 
EU 
European Union 
GCP 
Good Clinical Practice 
GDPR 
General Data Protection Regulation; in Dutch: Algemene Verordening 
Gegevensbescherming (AVG) 
IB 
Investigator’s Brochure 
IC 
Informed Consent 
METC  
Medical research ethics committee (MREC); in Dutch: medisch-ethische 
toetsingscommissie (METC) 
(S)AE 
(Serious) Adverse Event  
Sponsor
The sponsor is the party that commissions the organisation or performance of the 
research, for example a pharmaceutical 
company, academic hospital, scientific organisation or investigator.  
UAVG 
Dutch Act on Implementation of the General Data Protection Regulation; in Dutch: 
Uitvoeringswet AVG 
WMO 
Medical Research Involving Human Subjects Act; in Dutch: Wet Medisch-
wetenschappelijk Onderzoek met Mensen 
 
 

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SUMMARY 
 
Rationale: In the perioperative period anxiety for anesthesia and the surgical procedure is 
common. Breast cancer surgery patients have a higher level of anxiety compared to other 
patients undergoing (cancer) surgery. Relaxing breathing techniques, such as deep belly 
breathing are easy to learn and can have a beneficial effect on postoperative recovery. The 
quality of evidence in the perioperative setting is low. Slow-paced breathing at a frequency 
around 6 breaths per minute stimulates vagal activity and can possibly decrease anxiety, 
reduce mean blood pressure, postoperative pain and postoperative nausea and vomiting 
(PONV). 
Objective: We aim to examine the effects of a guided slow-paced breathing technique (Slow 
PACE breathing) performed at induction of anesthesia in patients undergoing surgery for 
breast cancer on anxiety, compared to usual care. We further aim to explore effects on pre-
operative blood pressure, per-operative need of hypnotics, postoperative pain and opioid 
use, PONV and patient satisfaction. 
Study design: Single center, two-group, prospective, randomized controlled trial.  
Study population: Patients scheduled for breast cancer surgery in the Antoni van 
Leeuwenhoekziekenhuis. 
Intervention: Performance of pre-trained guided Slow PACE breathing by the patient at 
induction of anesthesia for breast surgery.  
Main study parameters:  Anxiety scored by Spielberger's State Anxiety Inventory (STAI-S). 
Nature and extent of the burden and risks associated with participation, benefit and 
group relatedness: There are no physical risks related to the intervention. Participants 
randomized in the intervention group are trained in Slow PACE breathing and will follow this 
short daily routine until the day of surgery. All participants are asked to complete two 
questionnaires at baseline, and one short questionnaire on the day of surgery and at day 1.  
 
 

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1. INTRODUCTION AND RATIONALE 
 
1.1 Perioperative anxiety in breast cancer surgery patients 
In the perioperative period anxiety for anesthesia and the surgical procedure is common. In a 
survey of ~16.000 patients in the U.K. fear for anesthesia was the most important source of 
perioperative anxiety.1 Breast cancer surgery patients have a higher level of anxiety 
compared to other patients undergoing (cancer) surgery, such as surgery for urological 
cancer.2 
 
Perioperative anxiety has a strong influence on different aspects of anesthetic care. It has 
a negative influence on the induction and maintenance of anesthesia,3,4 postoperative pain,5 
and postoperative nausea and vomiting (PONV).6 
1.2 Rationale 
Relaxation techniques can have a beneficial effect on anxiety, postoperative pain and 
possibly length of hospital stay, but the quality of evidence is low. Breath focus with deep 
belly breathing is a well-known relaxation technique that is easy to learn. It can disengage 
the mind from distracting thoughts and sensations.7 The respiratory system is closely 
connected to the autonomic nerve system (ANS) via the vagal nerve.8 When breathing is 
manipulated to a slow frequency, it can increase vagal activity, decrease anxiety and reduce 
mean blood pressure.7,8 Stimulation of the vagal nerve is also known to decrease 
hyperalgesia10 and mitigate release of pro-inflammatory cytokines.11 The maximum effect is 
typically observed at a respiratory frequency around 6 breaths per min (0.1 Hz).8 This 
breathing technique is endorsed by the National Health Service (NHS) of the United Kingdom 
(U.K.) to reduce stress and anxiety.12 The application of slow-paced breathing and its vagus-
mediated effect on has not yet been investigated in the clinical perioperative setting.  
1.3 Aim 
Slow-paced breathing in this trial is deep belly breathing around a frequency of 6 breaths per 
min and called Slow PACE breathing in this study. Participants will be trained in  Slow PACE 
breathing pre-operatively and will practice the relaxation technique daily. We aim to examine 
the effects of Slow PACE breathing in breast cancer patients undergoing surgery on 
perioperative anxiety, performed at induction of anesthesia.  
Performance at induction of anesthesia is chosen as defined intervention to be able to 
closely monitor non-compliance. If a participant does not manage to perform Slow PACE 
breathing after training at induction, she will be considered non-compliant.  
We further aim to explore effects on blood pressure, per-operative need of hypnotics, 
postoperative pain and opioid use, PONV and patient satisfaction. 

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2. OBJECTIVES 
 
Primary Objective: The present study aims to examine the effects of pre-trained Slow PACE 
breathing performed at induction of anesthesia in patients undergoing surgery for breast 
cancer on anxiety, scored by Spielberger's State-Trait Anxiety Inventory, state scale (STAI-
S),13 compared to usual care. 
 
Secondary Objectives: To examine the effect of pre-operative Slow PACE breathing 
compared to usual care on: 
- 
mean blood pressure before induction 
- 
need of hypnotics during induction 
- 
post-operative pain and need of opioids 
- 
postoperative nausea and vomiting (PONV) 
- 
patient satisfaction  
- 
compare anxiety trait scored by Spielberger's State Anxiety Inventory (STAI-T)13 and 
general anxiety scored by the anxiety subscale of the Hospital Anxiety and 
Depression Scale (HADS-A)14 at baseline 
 
2.1 HYPOTHESIS 
Pre-trained Slow PACE breathing performed at induction of anesthesia attenuates 
perioperative anxiety. 

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3. STUDY DESIGN 
Single center, two-group, prospective, randomized controlled trial of patients scheduled for 
surgery for breast cancer. The trial will be conducted according to Good Clinical Practice 
(GCP) Guidelines and comply with the principles of the Declaration of Helsinki, all applicable 
national (WMO) and general data protection regulations (GDPR). 
 
 
 

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4. STUDY POPULATION 
4.1 Population (base)  
We aim to include patients undergoing surgery for breast cancer in the Antoni van 
Leeuwenhoekziekenhuis. 
 
 
4.2 Inclusion criteria 
In order to be eligible to participate in this study a subject must meet the following criteria: 
- 
Female 
- 
Undergoing surgery for breast cancer in the Antoni van Leeuwenhoekziekenhuis 
 
4.3 Exclusion criteria 
A potential subject who meets any of the following criteria will be excluded from 
participation in this study: 
- 
Age < 18 years 
- 
ASA ≥ 4 
- 
History of severe pulmonary illness: severe asthma or severe chronic obstructive 
pulmonary disease (COPD) GOLD III or IV  
- 
Unable to give written or oral informed consent 
- 
Patient refusal 
- 
Not able to understand Dutch 
- 
No internet access 
- 
Visual or hearing impairments interfering with reading and listening to the online 
material 
 
4.4 Sample size calculation 
With 75 patients per arm, 96% power would be achieved to detect a difference of 5 points 
in STAI-S score between intervention and control, with a mixed model analysis of 
repeated measures, at the two-sided 5% significance level in a design with 3 
measurements per patient (baseline before surgery, at pre-operative holding and on day 1 
post-operatively) having an autoregressive order 1 covariance structure when the 
standard deviation is 10 and the correlation between observations within the same patient 
is 0.6.15 The PASS software module for the test of two means in a repeated measures 
design was used for this calculation. Accounting for 5% drop-outs/non-compliant patients, 
79 patients per arm (total 158) would be needed. 
 

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Feasibility analysis 
After inclusion of 30 patients, we plan to assess the compliance to Slow PACE breathing 
just before induction. A failure to compliance is when a patient in the intervention group 
does not perform the guided Slow PACE breathing at induction of anesthesia, defined as 
breathing at rate of ≥ 10 breaths per minute. Assuming 95% patients will comply, the 
lower limit of a binomial exact 95% confidence interval for the compliance rate will be 
80%. If the lower limit of the 95% confidence interval for the compliance rate is below 
80%, then additional strategies will be deployed to ensure patients adhere to the training 
of the breathing technique (e.g. weekly calls to check-up and remind the patients) and 
patients with failure to compliance will be reviewed for point of improvement to increase 
compliance. 

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5. TREATMENT OF SUBJECTS 
5.1 Investigational treatment 
 
Intervention group:  
The intervention consists of performance of pre-trained Slow PACE breathing by the patient 
at induction of anesthesia for breast cancer surgery.  
 
  Slow PACE breathing 
Slow PACE breathing is a simple technique of deep belly breathing in a low frequency (0.1 
Hz = 6 breaths per minute), performed in supine position, synchronizing the breath with a 
breath pacer provided by an audio-guide. 
  
 Training 
Patients will be trained pre-operatively in the Slow PACE breathing technique using an 
instruction video combined with a personal instruction by video-call.  
Thereafter patients are requested to practice Slow PACE breathing once daily for at least 5 
minutes using a provided audio-guide, which patients can listen on their portable device (e.g. 
phone, tablet or laptop).   
 
5.2 Use of co-intervention 
 
Patients in both groups will not receive pre-medication with a benzodiazepine (e.g. 
oxazepam). 
 
6. INVESTIGATIONAL PRODUCT  
No investigational product or treatment is used in this study. 
 
7. NON-INVESTIGATIONAL PRODUCT 
No investigational product or treatment is used in this study. 

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8. METHODS 
8.1 Study parameters 
8.1.1 Main study parameter 
Anxiety scored by Spielberger's State Anxiety Inventory (STAI-S)13  
8.1.2 Secondary study parameters 
- 
Mean arterial pressure (MAP) just before induction  
- 
Total dose of hypnotics (propofol in milligrams) needed for induction of 
anesthesia 
- 
Highest numerical rating score for pain (NRS – a linear 11 point scale for self-
reported pain) during admission in the recovery room  
- 
Mean cumulative intravenous opioid dose administered during admission in the 
recovery room – converted to morphine equivalent dose (MEQ) 
- 
Occurrence of postoperative nausea and vomiting in the recovery room requiring 
anti-emetics 
- 
Patient satisfaction on a scale of 0 (extremely unsatisfied) to 10 (extremely 
satisfied) 
- 
Anxiety Trait scored by Spielberger's State Anxiety Inventory (STAI-T)13 at 
baseline 
- 
General anxiety scored by the anxiety subscale of the Hospital Anxiety and 
Depression Scale (HADS-A)14 at baseline 
 
8.1.3 Other study parameters 
Procedure related 
- 
Patient participation to the daily pre-operative practice of Slow PACE breathing  
 
Baseline and surgery parameters 
- 
Age 
- 
Length and weight 
- 
American Society of Anesthesiologists classification (ASA class) 
- 
Sociodemographic status (household, marital state, employment, education) 
- 
Intoxications 
- 
History of sedative or anti-depressive medication use 
- 
Type of breast cancer and type of breast cancer surgery 
- 
Underlying disease(s) 

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Intraoperative 
- 
The following vital signs are scored at baseline (e.g. measured on the outpatient 
department), at arrival on the operation room, just before induction and at the 
first measurement after induction:  
 
Systolic-, diastolic-, and mean blood pressure (mmHg) 
 
Heart rate (beats per minute)  
 
Oxygen saturation (SpO2 in %) 
 
Respiratory rate (breaths per minute)  
- 
Type and dose of anesthetic medication used for induction of anesthesia 
- 
Type and dose of vasoactive medication used during or within five minutes after 
induction 
- 
Anesthetic medication used for maintenance of anesthesia 
- 
Type and dose of administered opioids 
- 
Type and dose of other analgesia 
- 
Anti-emetics used 
- 
Perioperative anesthesiological management regarding locoregional techniques 
- 
Duration of anesthesia 
- 
Duration of surgery 
 
 
      Postoperative - recovery room   
- 
Vital signs  
- 
Highest NRS during admission in the recovery room  
- 
Mean cumulative intravenous opioid dose administered during admission in the 
recovery room (MEQ) 
- 
Postoperative nausea or vomiting (Y/N) 
 
8.2 Randomisation, blinding and treatment allocation 
Randomisation 
Patients will be randomly allocated to the study arms (usual care or Slow PACE 
breathing) using blocked randomization with age (<50 versus ≥50) as randomisation 
stratification factor in Castor. 
Blinding 
In this trial it is not possible to blind the patient or the investigators. 
 

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8.3 Study procedures 
8.3.1 
General 
To benefit patient comfort and because our easy-to-learn intervention is very low risk 
and low burden, we aim to provide all contact for this study online, supported by 
additional contact by (video)phone. We also aim to obtain informed consent digitally 
(see §11.2). We want to prevent unnecessary visits to the hospital just for the study, 
because many breast surgery patients do not live nearby the Antoni van 
Leeuwenhoekziekenhuis. 
 
8.3.2 
Measures of anxiety 
 
       Baseline (T0) 
After obtaining informed consent participants will fill out the baseline questionnaires 
online: STAI and HADS-A. 
 
Spielberger’s State-Trait Anxiety Inventory (STAI) is a well validated and widely used 
method of measuring an individual’s temperament or normal anxiety levels (Trait  
Anxiety) as well as their current or situational anxiety levels (State Anxiety).13 Each 
scale is comprised of 20 statements. The participant scores each question on a 4-
point scale ranging from 1 (not at all) to 4 (very much so), with the total score ranging 
from 20 to 80. Higher scores indicate higher levels of anxiety symptoms. A cut-off 
score of 40 is commonly used to define probable clinical levels of anxiety. In this 
study, we will ask participants to complete both Trait and State subscales at baseline. 
The STAI-T will give an estimation of patients at high risk for anxiety. 
 
Besides the STAI-T we will also take the HADS-A subscale at baseline to identify 
breast cancer patients with high anxiety levels.14 The Hospital Anxiety and 
Depression Scale is a questionnaire that has been found to be a reliable instrument 
for detecting states of anxiety and depression in a hospital setting. The HADS-A is the 
anxiety subscale that consists of seven items. Each item is rated on a 4-point scale 
(ranging from 0 = no not at all, to 3 = yes definitely), for a total score ranging from 0 to 
21. A subscale score above 8 denotes anxiety. 
The HADS-A is a shorter questionnaire then STAI-T and is used more commonly in 
the Antoni van Leeuwenhoekziekenhuis to measure general anxiety. We will compare 
STAI-T to HADS-A in prediction of high general anxiety. 
 

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Pre-operative (T1) 
On the day of surgery the participant will be asked complete the STAI-S questionnaire 
just before surgery on the iPad provided by the investigator. 
 
Post-operative (T2) 
Post-operatively the participant will be asked complete the STAI-S questionnaire 
online again. The participant will also be asked to score patient satisfaction on a scale 
of 0 (extremely unsatisfied) tot 10 (extremely satisfied). 
 
8.3.3 
Slow PACE breathing  
Training 
After completion of the baseline questionnaires, participants randomized in the 
intervention group will receive a link to the study site with a comprehensive instruction 
video explaining the Slow PACE breathing technique. Furthermore a ‘kick-off’ video-
call is planned with an investigator to give additional instructions and to answer any 
questions regarding the breathing technique.  
 
After the initial instructions participants are asked to practice Slow PACE 
breathing daily for at least 5 minutes, guided by an audio-guide to guide the breathing 
to a frequency of 6 breaths per minute (0.1 Hz). This audio-file will be available on the 
site. 
The participant will receive the researcher’s contact details, so she can always reach 
us in case of further questions or need for guidance. 
 
Pre-operative 
On the day of surgery, the participant will be transported to the operating room, where 
iv access is obtained and the participant is monitored by electrocardiogram,  and 
pulse oximetry and non-invasive blood pressure will be measure by a cuff every 2-3 
minutes (as is the normal procedure). The blood pressure at arrival on the operation 
will be noted (BP 0). 
 
After the ‘time-out procedure’ the participant randomized in the intervention 
group will be asked to start with the Slow PACE breathing technique. This will be 
guided by the same audio-fragment provided during the training, so the participant 
has a recognizable breath pacer. The blood pressure (BP 1) and the respiratory rate 
at the start of induction will be noted in both groups.  

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8.3.4 
Other study procedures 
Preoperative 
To monitor participation to the daily training sessions, participants in the intervention 
group will receive a daily email with a reminder and a link to the electronic CRF 
(Castor), in which they can score if they had time to practice the slow-paced breathing 
the day before (Y/N).  
 
Intra-operative  
Intra-operatively care as usual will be given to all patients. Anesthesia is induced with 
sufentanil and propofol. The blood pressure directly after induction will be noted (BP 
2). Anesthesia is maintained by propofol or sevoflurane at the discretion of the 
attending anesthetist. Depth on anesthesia will be monitored by the Bispectral index 
(BIS)-monitor and kept between 40 to 60. Routine general anesthesia, perioperative 
pain management, anti-emetic prophylaxis and fluid management will be performed 
and given in the intraoperative and postoperative period according to routine clinical 
use. Once anesthesia is terminated, patients are transported to the recovery room. 
 
Postoperative  
In the recovery room care as usual will be given to all patients. The patient’s 
respiratory rate, SpO2 and heart rate are measured continuously and a non-invasive 
blood pressure is measured at least every 15 minutes. Recovery room nurses are 
aware of the study protocol, but unaware of treatment allocation. 
On arrival, the patient is asked to rate their pain on the 11 point Numerical Rating 
Scale and is asked whether they require any further pain relief. They are also asked 
for nausea. 
All medications given and all pain scores and postoperative nausea or vomiting are 
noted in the electronic patient record. At least 2 NRS scores are noted for every 
patient (one on arrival and one before discharge).  
 
End of study period 
Data acquisition ends after completion of the post-operative questionnaire (STAI-S) 
and scoring of patient satisfaction. 
 

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8.4 Withdrawal of individual subjects 
Subjects can leave the study at any time for any reason if they wish to do so without 
any consequences. The subject can either email or call the researcher on the 
provided email or phone number at any time to inform the researcher. The 
investigator can decide to withdraw a subject from the study for urgent medical 
reasons.  
8.5 Replacement of individual subjects after withdrawal 
 Subjects withdrawing consent before any data are collected will be replaced. 
8.6 Follow-up of subjects withdrawn from treatment 
Patients who are withdrawn by their physician will be subjected to the same follow 
up as per the study protocol. When a patient withdraws their consent they will not be 
subjected to follow–up. 
8.7    Premature termination of the study 
In case the study is ended prematurely, the investigator will notify the accredited 
METC within 15 days, including the reasons for the premature termination. Reasons 
for premature termination could be a slow inclusion rate.  
 
9. SAFETY REPORTING 
9.1 Temporary halt for reasons of subject safety 
In accordance to section 10, subsection 4, of the WMO, the sponsor will suspend the 
study if there is sufficient ground that continuation of the study will jeopardise subject 
health or safety.  The sponsor will notify the accredited METC without undue delay of a 
temporary halt including the reason for such an action. The study will be suspended 
pending a further positive decision by the accredited METC. The investigator will take 
care that all subjects are kept informed.  
 

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9.2 AEs, SAEs and SUSARs 
9.2.1 Adverse events (AEs) 
Adverse events are defined as any undesirable experience occurring to a subject 
during the study, whether or not considered related to trial procedure. All adverse 
events reported spontaneously by the subject or observed by the investigator or his 
staff will be recorded. 
 
The investigator will report all AEs to the sponsor without undue delay after 
obtaining knowledge of the events, except for the following AEs: 
 
AEs that are a result of the surgical procedure 
 
9.2.2 Serious adverse events (SAEs) 
A serious adverse event is any untoward medical occurrence or effect that  
- 
results in death; 
- 
is life threatening (at the time of the event); 
- 
requires hospitalisation or prolongation of existing inpatients’ hospitalisation; 
- 
results in persistent or significant disability or incapacity; 
- 
is a congenital anomaly or birth defect; or 
- 
any other important medical event that did not result in any of the outcomes listed 
above due to medical or surgical intervention but could have been based upon 
appropriate judgement by the investigator. 
An elective hospital admission will not be considered as a serious adverse event. 
 
The investigator will report all SAEs to the sponsor without undue delay after 
obtaining knowledge of the events, except for the following SAEs: 
 
SAEs that are a result of the surgical procedure 
 
SAEs that are unrelated to the breathing technique 
 
The sponsor will report the SAEs through the web portal ToetsingOnline to the 
accredited METC that approved the protocol, within 7 days of first knowledge for 
SAEs that result in death or are life threatening followed by a period of maximum of 8 
days to complete the initial preliminary report. All other SAEs will be reported within a 
period of maximum 15 days after the sponsor has first knowledge of the serious 
adverse events. 

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9.2.3 Suspected unexpected serious adverse reactions (SUSARs) 
Not applicable 
 
9.3 Annual safety report 
Not applicable 
 
9.4 Follow-up of adverse events 
All AEs will be followed until they have abated, or until a stable situation has been 
reached. Depending on the event, follow up may require additional tests or medical 
procedures as indicated, and/or referral to the general physician or a medical specialist. 
SAEs need to be reported till end of study within the Netherlands, as defined in the 
protocol  
 
9.5 Data Safety Monitoring Board (DSMB) 
In this low risk study with no additional risks for the patient, we do not have a DSMB. 

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10. STATISTICAL ANALYSIS 
10.1 Sample size calculation 
See Section 4.4 for details. 
10.2 Analysis sets 
Analyses will be performed on an intention-to-treat (ITT) basis on all randomized patients. 
A per-protocol analysis set (PPS) will comprise all randomized patients excluding the 
non-compliant. Additional sensitivity analyses will be performed on the PPS.  
10.3 Primary study parameter 
For analyzing the STAI-S, a mixed model for repeated measures data (T1= pre-operative, 
and T2= post-operative) will be used to test for differences between study arms, adjusted 
for STAI-S at baseline and randomization stratification factor age group. Akaike’s 
information criteria (corrected) and Bayesian information criteria will be used for choosing 
the correlation structure. Diagnostic residual plots will be used to inspect model 
assumptions. In a separate exploratory analysis, STAI-T at baseline (dichotomized for 
anxiety status with cut-off 40 (see protocol Section 8.3.2) will be added as an explanatory 
variable in the regression, with and without interaction with study arm. The same will be 
done with HADS-A at baseline, dichotomized using cut-off 8 (Section 8.3.2). 
 
Additional analyses will be performed on the primary study parameter: Differences in 
STAI-S between measurements T0 and T1, between T1 and T2 and between T0 and T2 
will be compared between study arms using linear regression models for each 
comparison, adjusting for baseline measurements.  
 
10.4 Secondary study parameters 
 
1. MAP just before induction  
2. Total dose of hypnotics (propofol) needed for induction of anesthesia 
3. Highest NRS during admission in the recovery room  
4. Mean cumulative intravenous opioid dose administered during admission in the 
recovery room – converted to morphine equivalent dose (MEQ) 
5. Occurrence of PONV in the recovery room 
6. Patient satisfaction on a scale of 0 – 10 
7. Anxiety Trait scored by Spielberger's State Anxiety Inventory (STAI-T)13 at 
baseline 

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8. General anxiety scored by the anxiety subscale of the Hospital Anxiety and 
Depression Scale (HADS-A)14 at baseline 
 
Descriptive statistics will include total counts, mean, median, standard deviation (SD), 
range and interquartile range (IQR. For secondary endpoints 1 to 4, study arms will be 
compared using a Mann-Whitney U-test or an independent samples t-test, and 95% 
confidence intervals for the difference of means, or of medians (based on a 
nonparametric bootstrap procedure) will be obtained, depending on distributional 
assumptions. For study endpoints 5 and 6 chi-square tests (Fisher’s exact test in case of 
sparse data) will be used for testing for differences between groups. The Cochran-
Armitage test might be employed to test for trends in patients satisfaction. Secondary 
endpoints 7 and 8 will be each analyzed with receiver operating characteristic (ROC) 
curves, calculating the area under the curve (AUC) and 95% confidence interval and 
providing sensitivity, specificity, positive predictive value and negative predictive value. 
The AUCs for endpoints 7 and 8 will be compared using DeLong’s test for correlated 
ROC curves. 
To further explore the blood pressure before and after induction of anesthesia between 
groups, study arms will be compared similarly to the primary endpoint, by using a mixed 
model for repeated measures data, taking measurements of MAP at arrival on the OR 
(BP0), at start of induction (BP1) and just after induction (BP2) in an exploratory analysis. 
Graphical tools will be used to visualize the data (e.g. spaghetti plots) together with 
descriptive statistics (total opioid dose endpoint) per time point.  
 
10.5 Other study parameters 
Demographic data, baseline vital signs, NRS scores, perioperative administered 
cumulative drugs dosage, applied loco-regional techniques and duration of anesthesia 
will be reported.  
 
10.6 Interim analysis  
No planned interim analysis will be performed 

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11. ETHICAL CONSIDERATIONS 
11.1 Regulation statement 
The study will be conducted according to the principles of the Declaration of Helsinki (7th 
version of Fortaleza, Brazil, October 2013) and in accordance with the Medical Research 
Involving Human Subjects Act (WMO) and comply with Good Clinical Practice (GCP) 
Guidelines and all applicable national regulatory requirements and general data protection 
regulations (GDPR). 
 
11.2 Recruitment and consent 
11.2.1 Recruitment 
Patients will be screened for eligibility during the routine preoperative consultation. 
Should a patient be eligible, then she will be contacted by one of the researchers by 
phone to receive oral information about the study. This contact will take place at least 2 
weeks prior to the surgical procedure.  
Many patients in this population live far from the hospital and do not frequently visit the 
Antoni van Leeuwenhoek hospital in person. If receiving neoadjuvant treatment, they 
often receive this in a hospital near their home address. To benefit patient comfort and 
because our easy-to-learn intervention is very low risk and low burden, we aim to provide 
all contact for this study online, supported by additional contact by (video)phone. We 
used the ‘Handreiking elektronische toestemmingsverlening voor deelname aan medisch-
wetenschappelijk onderzoek, 22 augustus 2022’ and the ‘Checklist METC NedMec 
eConsent (NL) version 1 jan 2023’ provided by the Centrale Commissie Mensgebonden 
Onderzoek (CCMO) to ensure compliance with article 6 lid 2 WMO. 
If a patient is interested in participation, the document with the patient information and 
informed consent form will be sent digitally in an attachment by email using Zivver.  
Zivver is a service used in the AvL to send and receive information securely between 
patients and doctors in end-to-end encrypted emails protected by a personal password. 
Only the sender and the recipient can open the email and access the attached files. 
Zivver nor the IT department has access to the personal password, nor to the decryption 
key. This means that nobody but the sender and the recipient of the message can decrypt 
the message and read its content. Zivver complies with the concerning privacy and 
information protection regulations, like GDPR.   
In Zivver the researcher can audit if the email has been received and opened by the 
recipient. The IT department has access to the audit-logs in which they can audit when 

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and where the email has been accessed and if any settings have been changed, without 
having access to the content of the email.  
11.2.2 Consent 
The patients will be given sufficient time, at least 48 hours, to consider their decision and 
discuss this with their relatives or the independent expert. If the patient is willing to 
participate, oral consent is obtained by telephone. Hereafter an email with the patient 
information and informed consent form (IFC), signed and dated by the researcher, will be 
sent as attachment using Zivver to the email address that the participant personally gives 
to the researcher during this telephone contact. This email is secured twice with a 
personal password which the researcher will give to the participant during the same 
phone call. The participant will sign and date the IFC and send it back as attachment to 
the researcher by email using Zivver. The participant will thus have a digital copy of the 
IFC. If the patient prefers to give written consent personally, then an appointment with 
one of the researchers will be made in the hospital to obtain written informed consent and 
for further personal contact and information.  
The IFC signed by both participant and researcher will be stored digitally and will be 
safeguarded by the primary investigator digitally and protected by a password (also see 
§12.1).  
11.3 Objection by minors or incapacitated subjects  
Not applicable. 
11.4 Benefits and risks assessment, group relatedness 
The patient risk is negligible. The patient burden comprises of the training instruction, 
daily practice and completing the questionnaires is considered minimal. 
11.5 Compensation for injury 
The sponsor/investigator has been granted a dispensation of the liability insurance by the 
accredited METC. 
11.6 Incentives  
As this is an investigator initiated study, without additional funds, no financial incentive is 
available for patients. The patients in the intervention group are trained a stress reducing 
breathing technique, which they can apply in other stressful situations. The control group 
will have access to the training video and audio fragments on request, after the study has 
finished. 

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12. ADMINISTRATIVE ASPECTS, MONITORING AND PUBLICATION 
12.1 Handling and storage of data and documents 
All data will be handled confidentially and anonymously. Every subject will receive a 
subject identification code that contains no patient identifying data. The code list and key 
to the code will be safeguarded by the primary investigator digitally and protected by a 
password. Should other parties, such as a monitor or the Inspectie Gezondheidszorg en 
Jeugd, require data to be traced back to an individual subject, this code list can be used. 
All involved parties will handle patient data in a confidential manner. All relevant data will 
be recorded and stored in an electronic case report form (eCRF) using this identification 
code. Castor will be used to minimize errors and to ensure traceability. The data will be 
recorded in the eCRF at the bedside, or they will be extracted from the electronic patient 
record. All signed digital informed consent forms will be stored digitally, safeguarded by 
the primary investigator and protected by a password. The local researchers and project 
leader are responsible for data processing and are the only people that have access to 
the source data. All data will be stored for the length of the study and for 15 years 
afterwards, for further publication. All handling of personal data will comply with the Dutch 
Personal Data Protection Act. 
12.2 Monitoring and Quality Assurance  
As this trial is a low risk trial, we protocolize for a planned monitoring once a year.  
12.3 Amendments  
Amendments are changes made to the research after a favorable opinion by the 
accredited METC has been given. All amendments will be notified to the METC that gave 
a favorable opinion.  
Non-substantial amendments will not be notified to the accredited METC and the 
competent authority but will be recorded and filed by the sponsor.  
12.4 Annual progress report 
The sponsor/investigator will submit a summary of the progress of the trial to the 
accredited METC once a year. Information will be provided on the date of inclusion of the 
first subject, numbers of subjects included and numbers of subjects that have completed 
the trial, serious adverse events/ serious adverse reactions, other problems, and 
amendments.  
12.5 Temporary halt and (prematurely) end of study report 
The investigator/sponsor will notify the accredited METC of the end of the study within a 
period of 8 weeks. The end of the study is defined as the last patient’s last visit.  

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The sponsor will notify the METC immediately of a temporary halt of the study, including 
the reason of such an action.  
In case the study is ended prematurely, the sponsor will notify the accredited METC 
within 15 days, including the reasons for the premature termination. 
Within one year after the end of the study, the investigator/sponsor will submit a final 
study report with the results of the study, including any publications/abstracts of the study, 
to the accredited METC.  
 
12.6 Public disclosure and publication policy 
This study has been registered with the Netherlands Trial Register under the trial number 
NL84554.041.23. The results of the study will be published in a peer-reviewed (inter-) 
national scientific journal. We will submit analyses to scientific journals in the field of 
anesthesiology. The results of this study will be disclosed unreservedly according to the 
Central Committee on Research Involving Human Subjects (CCMO) statement on 
publication policy (http://www.ccmo.nl/attachments/files/ccmo-statement-publicatiebeleid-
3-02-en.pdf).  Data will be made accessible according to the FAIR guidelines.  
 
13. STRUCTURED RISK ANALYSIS  
Not applicable.  
 
 

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