The protocol conforms to the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) guideline (17) and describes a single centre, individual parallel group, randomised, feasibility RCT with semi-structured interviews, economic scoping and the incorporation of an exploratory physiology study. A study flow chart is illustrated in Figure 1; schedule for enrolment, intervention and follow up is shown in Table 1, with associated SPIRIT checklist presented in Supplementary Information 1.
Table 1: SPIRIT study schedule
|
|
Timepoint
|
|
Data
|
Enrollment
|
Baseline
|
Pre-intervention
|
During intervention
|
5 mins post intervention
|
Duration of study period
|
6 month follow up
|
Enrolment
|
Eligibility screening
|
X
|
|
|
|
|
|
|
Consent
|
X
|
|
|
|
|
|
|
Allocation
|
X
|
|
|
|
|
|
|
Intervention
|
Standard Care
|
|
|
|
X
|
|
|
|
MI-E intervention
|
|
|
|
X
|
|
|
|
Assessments: Baseline demographic outcome
|
Demographics
(age, gender, predicted body weight, history of lung disease, smoking history)
|
|
X
|
|
|
|
|
|
Reason for intubation
|
|
X
|
|
|
|
|
|
Date of hospital and ICU admission
|
|
X
|
|
|
|
|
|
Date of intubation
|
|
X
|
|
|
|
|
|
Ventilator settings
|
|
X
|
|
|
|
|
|
Airway type and size
|
|
X
|
|
|
|
|
|
APACHE II score
|
|
X
|
|
|
|
|
|
Assessments: Clinical outcomes
|
Use of HFOT, NIV, tracheostomy
|
|
|
|
|
|
X
|
|
Use of physiotherapy interventions
|
|
|
|
X
|
|
|
|
LUS score
|
|
|
X
|
|
X
|
|
|
Patient pain/discomfort
(CPOT; NRS)
|
|
|
X
|
|
X
|
|
|
CVS parameters
(HR, SBP, DBP)
|
|
|
X
|
|
X
|
|
|
Ventilator parameters (vent settings, resistance, compliance)
|
|
|
X
|
|
X
|
|
|
Respiratory parameters
(RR, SpO2)
|
|
|
X
|
|
X
|
|
|
Assessments: Health economics
|
-resource use (staffing requirements; suction frequency; consumable use; antibiotic use; physiotherapy oncall use)
-QOL (EQ-5D-5L)
|
|
|
|
X
|
|
|
X
|
Assessments: Safety
|
Adverse events
|
|
|
|
X
|
X
|
X
|
|
Abbreviations: APACHE II: Acute Physiology and Chronic Health Evaluation; CPOT; Critical Care Pain Observation Tool; DBP: diastolic blood pressure; HFOT: high flow oxygen therapy; hr: heart rate; ICU: intensive care unit; LUS: lung ultrasound; NIV: non-invasive ventilation; NRS: numeric rating scale; SBP; systolic blood pressure; RR: respiratory rate; SpO2: peripheral oxygen saturations; QOL: quality of life
Feasibility RCT
The study will be conducted in a 21 bed general adult ICU, within a large UK National Health System (NHS) teaching hospital. The unit has approximately 1250 admissions annually and typically admits adults with any condition except cardiac or neuro surgery.
Participant identification, recruitment and allocation
Eligibility
A research team member will screen all ICU patients on a daily basis against the study eligibility criteria. Our inclusion criteria comprise:
-
Adult (≥16 years)
-
Expected to require invasive mechanical ventilation for >48 hours
-
Clinician identified pre-extubation problems with secretion management defined as poor/weak cough effort and/or secretion load difficult to clear with usual airway clearance management i.e. suctioning, manual techniques, positioning etc (as assessed by the treating physiotherapy clinical team)
-
Identified as ‘ready to wean or weaning’ by the treating clinical team and on a spontaneous mode of ventilation for example Continuous Positive Airway Pressure (CPAP) or Pressure Support Ventilation (PSV).
Our exclusion criteria comprise:
-
Positive End Expiratory Pressure (PEEP) >10 cmH2O;
-
Fraction of inspired oxygen (FiO2) >0.7;
-
Hemodynamic/cardiovascular instability as defined as noradrenaline infusion of >0.25mg/kg or arrhythmia requiring intervention;
-
Recent untreated pneumothorax (current admission with no chest drain in situ);
-
Unable to use MI-E pre/post extubation (contraindications to facemask use including facial/cranial trauma, recent facial surgery; active upper gastrointestinal bleeding/uncontrolled vomiting; recent upper abdominal/thoracic surgery with at risk anastomosis; acute air trapping i.e. status asthmaticus);
-
Pre-existing neuromuscular condition affecting respiratory muscles;
-
Pre-existing use of MI-E in the community;
-
Pre-existing permanent tracheostomy;
-
Treatment withdrawal expected within 24 hours or not expected to survive;
-
Re-admission to ICU following index admission within same hospital episode; and
-
Previous participation in the study
Randomisation and allocation concealment
Using the online randomisation system Sealed Envelope™” (that conceals allocation), an ICU research team member will randomise a patient once informed consent/informed advice has been obtained and demographic data collected. Participants will be randomised using a 1:1 allocation to either (A)-control arm (standard care) or (B)-intervention arm (MI-E plus standard care). Blinding of participants, clinicians and outcome assessors will not be possible due to the nature of the intervention.
Study Arms
A. Control arm (standard care)
Patients will receive standard care in relation to mechanical ventilation, ventilator weaning, rehabilitation, standard physiotherapy techniques such as positioning, manual techniques (percussion, expiratory vibrations, expiratory shakes), manual/ventilator hyperinflation, endotracheal suctioning and nebulisation. Respiratory physiotherapy treatments will be individualised to patient need at the discretion of the treating physiotherapist and not protocolised. Decisions to extubate and re-intubate will be at the discretion of the attending physician with reason(s) documented.
B. Intervention arm (MI-E plus standard care)
For the intervention arm, we will use the MI-E device, Clearway 2 (Breas Medical LTD, Stratford-Upon-Avon, Warwickshire, UK). This device is reusable between patients with single use circuit, filter and interface (mouthpiece, facemask and flexible catheter mount).
Whilst intubated, treatment will include a minimum of two MI-E sessions via the endotracheal tube (with cuff inflated) following randomisation and prior to extubation. MI-E settings (mode, pressure, timings, flow) will be individualised to each patient based on patient tolerance, chest expansion and secretion clearance (as assessed by treating physiotherapist, see supplementary file 2). There will be no minimum/maximum time between MI-E sessions. Following extubation (and up to 48 hours), patients will receive MI-E delivered via facemask or mouthpiece up to 2 times each day.
Outcomes
Feasibility outcomes are listed in Table 2. Clinical endpoints will be collected to understand the feasibility of their collection informing conduct of a future adequately powered trial and not to conduct hypothesis testing related to causation. Feasibility will be assessed using pre-defined progression criteria (Table 3).
Table 2: Feasibility outcomes
Feasibility outcome
|
Measurement detail
|
Proportion of eligible patients approached, consented and randomised
|
Screening log and randomisation records
|
Proportion of MI-E treatment sessions completed
|
Case report form
|
Proportion of recruited patients with all clinical outcomes recorded
|
Case report form
|
Frequency of adverse events
|
Case report form
|
Attrition (participant withdrawal and loss to follow up)
|
Case report form and withdrawal records
|
Acceptability of intervention and trial processes to participants and clinicians
|
Qualitative interviews
Acceptability of intervention measure (AIM)/Intervention Appropriate Measure (IAM)/Feasibility of Intervention Measure (FIM)
|
Acceptability of outcome measures to participants and clinicians
|
Qualitative interviews
|
Table 3: Progression criteria (based on feasibility parameters)
|
Summary
|
Action required
|
Go (green)
|
Recruitment: >70% expected recruitment target
Follow up: >75% data completeness
Adherence: >75% adherence to intervention
|
Feasible to continue to main trial
|
Amend (amber)
|
Recruitment: 50-70% of expected recruitment target
Follow up: 65-75% data completeness
Adherence: 65-75% adherence to intervention
|
Identify remediable factors, discuss with trial management group
|
Stop (red)
|
Recruitment: <50% of expected recruitment target
Follow up: <65% data completeness
Adherence: <65% adherence to intervention
|
Do not progress to main trial, unless there is a strong case that unanticipated remediable factors have been identified
|
Data collection
Prior to randomisation the research team will collect baseline demographic and clinical characteristic data from the electronic medical record. Data include general demographics, reason for intubation, date of hospital and ICU admission, date of intubation, admission Acute Physiology and Chronic Health Evaluation (APACHE II), baseline ventilator settings and airway type and size (Table 1).
Clinical outcomes (Table 1) will be measured before, on completion and 5 minutes after physiotherapy sessions for both study arms. We have selected exploratory clinical outcomes using the core outcome measure set for critical care ventilation trials (18). In addition, we will record the number and type of physiotherapy treatments provided, patient pain/discomfort, cardiovascular parameters, ventilatory parameters and respiratory parameters (See Table 1 for further details).
To assess the feasibility of collecting data for a cost utility analysis in a future trial we will collect:
-
EQ-5D-5L at 6 months post ICU discharge
-
Resource use associated with the MI-E intervention and standard care
We will identify the following resource use during the index admission: MI-E device associated resource use including staffing requirements (time spent delivering an MI-E treatment, grade/seniority of staff administering treatment) and consumables used. Patient related resource use will include endotracheal suction frequency by nursing staff (over a 24-hour period), use of non-invasive ventilation (NIV), High Flow Oxygen Therapy (HFOT) and tracheostomy, antibiotic use, physiotherapy on-call use (planned and unplanned), ICU LOS, ICU re-admission and hospital LOS. For the purposes of the feasibility trial these will be reported as frequencies and time duration (hours).
Outcome description
Re-intubation rate: Re-intubation rate will be calculated for the 48 hours following extubation. This is the planned primary outcome for the future planned trial.
Pain scores: We will measure pain using either the ‘numeric rating scale’ (NRS) (19) or the Critical Care Pain Observation Tool (CPOT) (20).The NRS is a self-reported measure where patients rate pain presence and severity on a scale from 0 (no pain) to 10 (worst pain possible). If a patient is unable to rate pain, we will use the CPOT. The CPOT is a valid measure to determine pain presence with four domains: facial expressions, body movements, compliance with the ventilator or vocalisation, and muscle tension. Each domain is scored 0-2 with a maximum score of eight. A CPOT score >2 indicates pain presence. We will document pain presence before and after a physiotherapy session.
Cardiovascular, ventilator and respiratory parameters: These measures include heart rate, systolic and diastolic blood pressure, ventilator settings, airway resistance and lung compliance, peripheral oxygen saturations, and respiratory rate measured pre and post physiotherapy in both the intervention and control arms.
Acceptability: We will use three validated questionnaires to measure acceptability; Acceptability of Intervention Measure (AIM); Intervention Appropriate Measure (IAM) and Feasibility of Intervention Measure (FIM) (21). These will be measured immediately post MI-E intervention.
Adverse events: We will record occurrence of the following during a MI-E treatment and control arm interventions: HR, SBP, DBP increase/decrease >20% baseline; arrhythmia (requiring intervention); pneumothorax; acute desaturation to <85% or >10% below baseline; accidental extubation; and cardiopulmonary arrest.
Statistics and data analysis
Sample size calculation
As this is a feasibility trial a formal sample size calculation based on statistical power to detect a specified treatment effect size is not appropriate. We have selected a sample size of 50 participants based on measurement of feasibility parameters with adequate precision. The participating ICU admits approximately 1250 patients annually with potentially four to five eligible patients each week (minimum of 200 per year). We anticipate recruiting 50 over a 12-month period would be achievable, with an estimated recruitment rate of 25% and a confidence interval width of 0.12.
Statistical analysis plan
The analysis and reporting of this study will be consistent with the CONSORT guidelines extension to feasibility studies (22). This study is not designed or powered to carry out formal hypothesis testing. Participant flow through the study will be summarised and presented in a flow diagram. Descriptive statistics for patient characteristics will be reported overall and by treatment group; as means or medians with measures of dispersion for continuous outcomes (as appropriate given distribution) and frequencies and percentages for categorical outcomes. Only descriptive statistics will be used in the physiology sub-study due to the small sample size proposed. Patient reported and clinical feasibility outcomes will be presented and assessed for completeness of data.
Safety reporting
The attending consultant physician is responsible for assessing all adverse events (AEs) and categorising seriousness, expectedness, and relatedness. A list of events that can be expected during this trial, or within this patient population can be found below.
The following adverse events can be expected during this trial, or within this patient population:
-
Accidental extubation during the intervention
-
Cardiovascular changes (including but not exclusive to hypo/hypertension, brady/tachycardia, arrhythmias)
-
Pneumothorax
-
Sputum plugging during the intervention
-
Pulmonary complications such as pneumonia
It is the responsibility of the sponsor, chief investigator and delegated individuals to ensure that the dignity, rights, safety and well-being of research participants are given priority at all times and appropriate action is taken to ensure their safety. The recording and reporting of safety events will be in accordance with Good Clinical Practice (GCP) Guidelines and study sponsor’s ‘research safety reporting’ standard operating procedure.
Semi structured qualitative interviews
Study design and recruitment
Interviews with patient participants in the intervention arm and their family members will take place within six weeks of discharge from ICU. We will exclude participants who have no recall of their ICU stay or the MI-E intervention. Interviews will be conducted by the Chief Investigator (ES).
Clinician interviews will be conducted with staff from the ICU clinical team including doctors, nurses and physiotherapists who have had exposure to the MI-E intervention within the preceding 4 weeks. These interviews will be completed by a member of the study team (SV) to eliminate potential bias presented due to a working relationship with ES. These will occur during trial recruitment and within 4-weeks of exposure to a patient in the intervention arm of the trial.
We have based the interview topic guides on the Theoretical Framework of Acceptability (TFA) (23). Interviews will be completed virtually via an online platform (Microsoft Teams).
Sampling and recruitment
Convenience sampling of 10-15 participants (24) will be used. Clinicians will be approached based on gaining maximal variation sample regarding profession and years of clinical experience. Patients and family members recruited into the study will be approached for consent once the patient has been discharged from ICU.
Interview data collection and analysis
On interview commencement, we will collect clinician demographic data (clinical profession, years working in profession and on ICU, highest educational level obtained); patient demographics including age, reason for ICU admission, ICU LOS, or family demographics (relationship to patient) as relevant to the interview participant.
Interviews will be digitally recorded and transcribed verbatim by an university-approved transcription service. Transcripts will be checked for accuracy and anonymised. Data will be analysed using reflexive thematic analysis (24, 25) and using TFA domains through first level coding. Thematically similar responses will be grouped in a process of data reduction and compared across transcripts. Tables will be produced to highlight key thematic content, within each TFA domain with consideration of responses from both patients and clinicians, and with the aim of highlighting similar and discordant themes. Domains will be identified as salient based on their frequency of inclusion and potential strength of impact. NVivo software will be used to support this process.
Embedded exploratory physiology study
Background
During invasive ventilation, positive pressure breaths are delivered followed by passive expiration. In contrast, MI-E delivers both positive (insufflation) and negative (exsufflation) pressure breaths. Lung recruitment and de-recruitment are important considerations in intubated and ventilated patients (26, 27). Barotrauma and volutrauma associated with large tidal volumes are well documented, with low volume lung protective ventilation now standard of care, particularly for patients with acute lung injury (27). De-recruitment of lung units due to small tidal volumes and loss of PEEP through ventilator disconnection can have an equally adverse impact on oxygenation and effective ventilation, attenuating lung injury (26).To date, no studies have examined the extent of recruitment and de-recruitment as a result of positive and negative pressure delivery during MI-E application.
Sub-study aim
To examine lung recruitment and de-recruitment during MI-E application.
Sub-study design
We will use Electrical Impedance Tomography (EIT) (Pulmovista 500, Draeger Medical UK Ltd, Hertfordshire, UK) and Lung Ultrasound (VenueGoTM, GEHealthcare, London, UK) in a subset of patients in the intervention arm. We aim to recruit between five and ten patients.
EIT is a non-invasive, radiation free technique used at the bedside to provide pulmonary ventilation data in real-time (28). A series of 16 electrodes are placed around the chest wall, through which small electrical currents are passed to measure impedance, conductivity and permittivity. These measurements result in a 2D image illustrating end inspiratory and end expiratory lung volumes and regional distribution of ventilation. The technique is used clinically and in ICU research studies to examine ventilation strategies, PEEP titration, and effects of positioning (28, 29).
Lung Ultrasound Score (LUS): The lung ultrasound score is a semi-quantitative scoring method used to illustrate pulmonary aeration (30). We will use the previously described framework for practical application of the LUS in the ICU (31). The framework describes six areas of interest per lung. Each hemithorax is divided into anterior, lateral, and posterior regions with each region having an upper and lower position. There is one representation point per area scanned and scored between 0 and 3 as part of this framework. Total scores range between 0 and 36. We will calculate LUS score pre and post intervention. Scans will be completed by a clinician with Focused Ultrasound in Intensive Care (FUSIC) accreditation who will be blinded to group allocation.
Data collection and reporting
We will record end inspiratory and end expiratory regional ventilation distribution via EIT before, during and 5 minutes after the MI-E intervention. The Lung Ultrasound Score will be calculated before and after the MI-E intervention (Table 3). Results will be presented as a case series.
Consent
On initial trial enrolment, patients may lack capacity to provide informed consent. As permitted in the UK, we will use a personal or nominated professional consultee. On regaining capacity, the patient will be informed of trial participation and informed consent will be sought.
Interview participants will be requested to provide consent at the point of recruitment. Verbal informed consent will also be sought and recorded at the start of each interview.
Study withdrawal and processes
Participants are free to withdraw from any element of the study at any time without providing a reason. Unless specifically stated by the individual, data collected up to that point will be retained for analysis.
Data management
All participants will be assigned a unique study identification number, which will be used in all study-related documentation. A record of names, contact details, hospital numbers and assigned trial numbers will be stored securely using a password protected Research Electronic Data Capture (REDCap) database only accessible to members of the research team.
Password protected audio digital recording of interviews will be uploaded to a university computer secure drive. All transcriptions will be labelled with a unique study identification number, edited to ensure respondents are pseudonymised (only clinician profession and banding/grading documented), and stored securely adhering to University data protection policies.
Consent forms (and any other documentation) with personal identifiable data will be stored in a locked filing cabinet (or locked equivalent). Participant details will be anonymised in any publications that result from the trial. At the end of the study, pseudonymised data will be stored in a secure research data storage repository, alongside the other study data (as per sponsor policies).
Study management
A Trial Management Group (TMG) will be responsible for overseeing day to day study management. The TMG will meet weekly. We formed a 12 member patient advisory group (PAG) who have informed decisions related to study design and will have ongoing input into study conduct, data analysis and interpretation and dissemination. Two PAG members will also participate in the Trial Steering Group (TSG) to ensure the patient voice is heard throughout the study. The TSG consists of 5 expert clinicians representing the ICU multi-professional team and has an independent chair. The group meet every 3 months during study conduct.