Development of a Complex Exercise Rehabilitation Intervention for People with Pulmonary Hypertension: The Supervised Pulmonary Hypertension Exercise Rehabilitation (SPHERe) Trial

Stage 1a Results

Table 1 Reproduced and adapted from McGregor et al 2018 (11) Re-use permitted under CC BY-NC

As included studies focused mainly on inpatient exercise programmes for people in groups 1 or 4, it was not possible to generalise the results of this systematic review across the spectrum of people with pulmonary hypertension. Our review of the published literature provided a broad framework within which our intervention could be developed. As many people with pulmonary hypertension have a primary diagnosis of heart failure or respiratory disease, we also reviewed existing guidelines for cardiopulmonary rehabilitation.

Stage 1b: Review of Rehabilitation Guidelines

Stage 1b Methods

We reviewed UK and other international guidance applicable to people living with chronic respiratory and cardiovascular conditions. The key guidelines include those published by the British Association of Cardiovascular Prevention and Rehabilitation (BACPR(16)), the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR,(17)) and the European Association of Cardiovascular Prevention & Rehabilitation (EAPC)(18).

 

Stage 1b Results

Findings from our review of cardiac rehabilitation guidelines are presented in Table 2.

International guidelines were broadly in agreement in relation to the safe and effective duration, intensity, frequency and type of exercise for cardiopulmonary rehabilitation. The guidelines are sufficiently flexible to allow different models of programme delivery, including home or centre based. We used these, combined with findings from our systematic review, to develop an outline of an exercise programme for people with pulmonary hypertension (Stage 2).

Stage 2: Expert opinion and stakeholder engagement

Stage 2 Methods

The SPHERe research team (n = 14) consisted of clinical academics with expertise in the development and implementation of complex exercise rehabilitation interventions (Fig. 2).

To holistically appraise the needs of people with pulmonary hypertension and their support network, we engaged widely with patients, multi-disciplinary professional agencies, and lay persons, identified through formal working relationships and informal networks. The research team identified key themes and priorities to form the outline for discussions, based on up-to-date evidence from our systematic reviews and review of clinical guidelines. We held a series of consensus meetings at the Warwick Clinical Trials Unit from April 2018 to September 2019. All stakeholders were invited to either attend in person or contribute remotely through telephone, e-mail, and video conference. Consensus responses were recorded and collated into the following categories: exercise dose (Frequency, Intensity, Time and Type (FITT) principles), exercise progression, psychosocial support and the feasibility of incorporating the intervention into current NHS rehabilitation programmes.

Stage 2 Results

The findings from the consensus meetings are summarised in Table 3.

 

Following the consensus/stakeholder meetings, we generated a framework for the draft intervention programme for pre-pilot testing.

 

Rationale and Development of SPHERe Intervention

Type of Exercise

One of the findings from previous studies investigating exercise and pulmonary hypertension (11) was that most programmes included both aerobic and resistance exercise. This is appropriate for this population; regular aerobic and resistance exercise training in pulmonary hypertension groups 1 and 4, and in other clinical populations (heart failure and pulmonary disease), leads to adaptations that reverse many of the histochemical features of skeletal myopathy (23–25). Patients with pulmonary hypertension (through discussion and pre-pilot testing) requested types of exercise that both reduced breathlessness and improved their ability to perform activities of everyday living. Functional exercises such as sit to stand and/or step-ups, may help reduce atrophy and restore muscle function, improving mobility and balance (26). Therefore, four to six resistance or functional exercises were included, to target all the major muscle groups, and compound (more than one muscle) rather than isolation (single muscle) exercises were incorporated (27), so that fewer exercises would be needed for whole body training. Each centre will have different resources available and so these standardised principles can be adapted to whatever resistance equipment is available at each site.

Exercise Dose and Setting

During the stakeholder meetings, it was agreed that the SPHERe intervention should include three exercise sessions per week; two supervised in a rehabilitation centre and one unsupervised at home. This was based on our review of existing pulmonary hypertension studies and international rehabilitation guidelines. The supervised exercise sessions were subsequently planned to last up to an hour (including, warm-up, aerobic component, Muscle Strength and Endurance (MSE) component, and cool down) and the home exercise sessions to last up to 45 minutes. These could be altered, initially dependant on the degree of limitation in our population, and then up-titrated during the programme.

Intensity

Our review of the published literature and pre-pilot experiences revealed a general reluctance to prescribe exercise greater than low-moderate intensity for people with pulmonary hypertension, most likely due to concerns of adverse events during exercise; e.g., syncope, severe dyspnoea (28). However, moderate intensity exercise (40–70% heart rate reserve, Borg scale 12–14, breathlessness scale 3–4)(16), is recommended for other rehabilitation populations (16, 27) some of whom may have pulmonary hypertension (groups 2 and 3) as a secondary condition. During our pre-pilot study we found that participants were, at first, very unwilling to exert themselves to this level due to repeated warnings not to do so from health professionals, family, friends etc. This was particularly evident during resistance exercise. Some participants required substantial reassurance and encouragement from the practitioner to achieve moderate intensity levels. Alongside gym familiarisation sessions, we included a behavioural session in the first week of the programme to reduce fear avoidance of physical activity. The intention was to educate participants that exercise, contrary to being detrimental to health, may be safe and beneficial.

Monitoring Intensity

The intensity of exercise should be high enough to stimulate beneficial adaptations by gradually overloading the cardiovascular and musculoskeletal system. This must be standardised and monitored at each session to ensure all participants receive the same intervention dose. Heart rate is commonly used to prescribe intensity in exercise programmes at percentages of maximum or predicted maximum (27). However, heart rate monitoring is not always reliable e.g. due to arrhythmias, medication, caffeine, anxiety etc, therefore the Borg scales of perceived exertion and dyspnoea (breathlessness) (29) were included so that target heart rate could be crosschecked with the subjective perception of the participant.

Starting Levels of Exercise

It was decided that starting level of exercise intensity and duration should be calculated from the results of an individual assessment prior to the exercise programme. Resting heart rate (RHR) was recorded after the participant sat in a quiet room and completed a medical history consultation with the practitioner. The peak heart rate response from participants during an Incremental Shuttle Walk Test(30) was used as the maximum heart rate (max. HR) required to calculate 40–70% heart rate reserve using the Karvonen formula (31). It was found to be preferable to initially prescribe exercise at the lower end of this range so as not to create undue anxiety around excessive fatigue and breathlessness. We opted to include Muscle Strength and Endurance (MSE) exercise in the programme as soon as possible, i.e. from week two onwards. Older adults (≥ 65 years) or those new to exercise, performed 10–15 repetitions at first to improve strength (27) at an intensity/weight resistance of 4–6 on the Borg Category Ratio (CR-10) scale after two repetitions(16). The CR-10 scale is a 10 point scale that differs from the 15 point RPE scale and is more accurate for resistance exercise(32).

Criteria for Progression

The duration and intensity of exercise prescribed must be progressed regularly for participants to receive a continual stimulus for adaptation and improvement for the whole programme. Therefore, we recommended that initially the duration of exercise was increased by 1–5 minutes per session until therapeutic levels of exercise were achieved i.e. at least 20 minutes duration at a moderate intensity range. During the pre-pilot, participants found the exercise sessions more acceptable once they had gained confidence in the gym environment, even as it became more challenging. Rate of progression was based on heart rate, perceived exertion and breathlessness recorded during exercise and through careful discussion with the participant. The exercise prescription booklet was used during the pre-pilot to record measures of intensity. This was reviewed each week by the practitioner and participant and progressed if intensity fell below the target ranges described earlier(16).

Progression of Resistance Training

We decided that the MSE sets, repetitions or resistance should be progressed if the CR-10 scale was lower than 3–4. One general rule for MSE progression is that if participants can perform 20 repetitions on their last set (27) then the resistance is almost certainly too low to produce an adaptation in strength. Therefore, it should be increased, allowing for the fact that perhaps as few as 8–12 repetitions can be performed at the new resistance level.

Home Exercise Programme

Our draft home exercise plan was tested by four participants. We received helpful feedback on how to improve materials, for example; being clearer about the explanation of the format of exercises and how to progress each week. The risk of participants potentially overexerting themselves whilst unsupervised at home was highlighted when one participant took two hours to complete the full home exercise plan which was intended to last 30–45 minutes. There was no adverse event on this occasion but the need for greater explanation was apparent. Our training day materials, practitioner manuals and ongoing support to sites were changed to ensure that practitioners review all home exercise plan record sheets each week during the supervised session. During the pre-pilot study we found that thirty minutes was required to adequately explain and demonstrate the home exercise plan. This is now incorporated into the first week of supervised exercise sessions.

Duration of SPHERe Programme

Most other clinical trials report exercise programmes lasting four to 15 weeks (12). In the UK, NICE (33) recommend 12 weeks as the optimal length for cardiac rehabilitation programmes. In practice however, longer programmes require more capacity/resource and can result in longer wait times for patients. In addition, adherence to longer programmes becomes difficult due to ill health, return to work or loss of motivation. The most common length in UK cardiac rehabilitation programmes in the eight partner sites we had approached was eight weeks (16 sessions), slightly shorter than the national average of 10.3 weeks (34). As the intention of SPHERe was to embed participants in existing cardiac rehabilitation programmes, the study team took a pragmatic decision for an eight week programme to encourage engagement and uptake by clinical rehabiltation centres.

Promoting Adherence

Behavioural interventions have been shown to increase adherence to physical activity interventions in adults (35). This, in combination with our patient stakeholder feedback, led to the provision of behavioural sessions (referred to by practitioners as ‘coaching’ sessions following participant feedback) to run in parallel with the supervised exercise sessions. The six sessions were designed in collaboration with an experienced health psychologist with the objective of attenuating the most common psychosocial barriers to exercise for this group. We decided to focus on increasing participants’ awareness of how irrational thoughts and feelings can influence their behaviour. Sessions were designed to investigate the pros and cons of changing a specific behaviour, for example; fear avoidance of exercise, with assistance to develop a specific plan incorporating motivation and goal setting. This was encouraged from the first assessment so that the exercise prescriptions were targeted at physical goals identified as important by patients during the stakeholder meetings. These goals included becoming less fatigued and breathless on exertion, being able to walk further, being able to climb stairs, generally increasing fitness, and regaining independence. There is evidence that linking exercise to daily activities can encourage adherence (26). Furthermore, once goals are agreed, a written ‘contract’ signed by practitioner and participant is recommended for improved adherence (36). This has been incorporated into the participant workbook and will be completed during week one of the programme.

Condition Specific Considerations for the Exercise Programme

Due to the higher risk of syncope in people with pulmonary hypertension, a thorough warm-up and cool-down are particularly important. A gradual increase in O₂ demand while muscles reach optimal metabolic efficiency and the cardiopulmonary blood vessels have had time to dilate fully, will avoid unnecessary breathlessness during activity. Likewise, the avoidance of sudden cessation of exercise via a gradual cool-down will reduce pooling of blood in the working muscles(37), light headedness, and vasovagal syncope (16).

We underestimated how ingrained activity avoidance was in this population, as result of years of health professional advice to avoid activity. We placed extra emphasis on this by introducing behavioural coaching and familiarisation sessions. Another consideration was that many people living with pulmonary hypertension were on long term oxygen therapy and extremely debilitated. During pre-pilot, one participant could only walk 30 metres with a rollator that carried her oxygen cylinder. Exercise programmes for the extremely debilitated cannot always use conventional exercise equipment as the minimum level of difficulty maybe too hard for patients to achieve for a meaningful duration. For some people, even getting onto some equipment, for example; an upright exercise bike or rower, may induce severe breathlessness. The introduction of adapted functional exercises, such as sit to stand from an elevated chair and step ups with a handrail, are more achievable and appropriate for the severely impaired. Furthermore, the necessity for ratings of breathlessness and exertion over heart rate was underlined by our experiences with the severely limited.

Overview of SPHERE Intervention

The final SPHERe programme has three core components (Figure. 3) See additional file 1 for TIDIER checklist.

1. Supervised gym exercise sessions (Weeks 1 to 8): up to 16 gym-based sessions held twice weekly over eight weeks, each session lasting for one hour, in an existing cardiopulmonary rehabilitation programme. The first two of these sessions will be ‘familiarisation sessions’ to introduce participants to the gym environment and programme.

2. Behavioural ‘coaching’ (Weeks 2 to 8); Six one-to-one sessions lasting 30 minutes each delivered before, or after, one of the weekly gym sessions.

3. Home exercise plan (Weeks 1 to 8); An individualised home exercise plan to be followed at least once each week, unsupervised at home.

Initial Assessment

To inform exercise prescription, an individual assessment will be performed with close clinical monitoring before starting supervised exercise,(28) as per standard practice in most cardiopulmonary rehabilitation centres. Exercise capacity will be assessed by the Incremental Shuttle Walk Test (30). Results will allow calculation of initial exercise prescription as per BACPR(16) guidelines.

Week 1: Gym Familiarisation Sessions

One-on-one familiarisation sessions will gradually introduce participants to the gym environment during the first week of the programme. The SPHERe practitioner will refine and optimise the exercise prescription, in agreement with the participant, to further reduce anxiety, whilst providing an induction into the gym/class setting.

Supervised Exercise Sessions

Participants will attend twice weekly, one-hour, supervised group exercise sessions within existing cardiopulmonary rehabilitation programmes. Exercise sessions will be individualised, moderate intensity exercise (40–70% heart rate reserve, Borg scale of perceived exertion;12–14, and breathlessness; 3–4)(16), that includes aerobic, muscular strength and endurance (MSE), and ‘functional’ exercise.

Behavioural Education Sessions

All participants will receive six, one-to-one, 30-minute, behavioural coaching support sessions with a trained SPHERe practitioner to promote adherence during the intervention period. These sessions will be held once per week, either before or after exercise.

Unsupervised Exercise: SPHERe Home Exercise Plan

Participants will be introduced to the home plan and then encouraged to follow the SPHERe home exercise plan every week. Participants and practitioners will select only 6–8 of the longer menu of 24 available exercises (Fig. 4, below)

The participant will then be instructed to perform these selected exercises in a ‘circuit’; i.e., one after another, and multiple circuits repeated as required. The practitioner will review the supervised and home exercise plan weekly with the participant and alternate and progress exercises as necessary.

Intervention Fidelity: Practitioner Training and Quality Control

To ensure standardisation of intervention delivery, all sites and practitioners involved in the SPHERe trial will have a full day of face to face practical and theoretical training with a clinical exercise physiologist (SE) and health psychologist (HS), who will provide input to deliver the behavioural education sessions, utilising motivational interviewing techniques and the COM B model (38). An assessment following training will be completed by practitioners to evaluate readiness to deliver the intervention and/or the need for further training. Practitioners will be given comprehensive manuals for intervention delivery (additional file 2) and phone call support as required.

The SPHERe intervention will be delivered by NHS clinical exercise physiologists (i.e. in possession of sport science degree) or chartered physiotherapists with a minimum of two years’ experience working with clinical populations.

All sites will be subject to regular quality control visit every 4–6 weeks. This is to ensure that exercise and behavioural education sessions for the SPHERe programme are being delivered in a standardised manner and provide support to rehabilitation teams. A separate process evaluation will assess programme delivery across sites.