Introduction

Background and rationale

Over 170,000 patients are admitted to adult, general critical care units in the NHS each year.1 Meta-analyses of outcome data for survivors indicate a pooled prevalence of 25% for clinically important post-traumatic stress disorder (PTSD) during the first 6 months after discharge from critical care.2 Similar figures for anxiety and depression are 40%3 and 34%,4 respectively. Patients who develop serious psychological morbidity are also at higher risk of further physical morbidities and mortality.5–7

Experiencing acute stress and early memories of frightening critical care experiences (e.g. hallucinations, delusions and nightmares), while in the unit, are among the known risk factors for longer-term, post-critical care psychological morbidity including PTSD, depression and anxiety.8–13

Research has estimated that ≈50% of patients experience acute stress, and up to two-thirds experience hallucinations and delusions, while in the critical care unit.14,15 Acute stress, including symptoms of anxiety, low mood and panic, may be caused by a range of difficult, cumulative experiences that are common for patients in critical care units: fear of dying; invasive treatments, such as mechanical ventilation; pain and discomfort; inability to communicate; and terrifying hallucinatory delusions.8,14,16,17 The aetiology of critical care hallucinations and delusions is unknown, but they have been linked to delirium, the provision and withdrawal of sedatives and other psychoactive drugs, effects of illness (such as sepsis), immobility, and sensory and sleep deprivation.8,15,18 Hallucinations and delusions are known, from the psychosis literature, to be exacerbated by, and comorbid with, acute stress. Critical care unit hallucinations frequently have horrifying themes such as conspiracy to kill by staff, torture, poisoning, demons, extortion or organ theft;19 thus, a vicious cycle of stress, confusion and terror is common for many, though not all, critical care unit patients.

In 2000, the UK Department of Health and Social Care recognised that the critical care unit was an extremely distressing place for patients and that there was considerable need for psychological support for patients.20 In 2009, the National Institute for Health and Care Excellence (NICE) recommended that all critically ill patients should be assessed for risk of non-physical (i.e. psychological) morbidity, and that those deemed to be at high risk of adverse outcomes, such as PTSD, should receive structured psychological support as part of an individualised rehabilitation plan, both during and after their critical care unit stay.21 Separately, a NICE evidence update on PTSD22 suggested that, compared with no psychological intervention, an early (delivered immediately), brief (three sessions), trauma-focused psychological intervention has the potential to reduce the development of subsequent symptoms; the evidence update also called for further research.22 However, little is currently done to alleviate patients’ stressful experiences in critical care units, because of a lack of strong evidence about what may help.

The modification of clinical risk factors for PTSD, such as duration of mechanical ventilation and sedation, has been discussed in the literature,23,24 but less invasive medical interventions or better drugs are currently not widely available. There is a lack of high-quality research evaluating psychological interventions in the critical care setting with a view to preventing the development of longer-term psychological morbidity.25 To date, only a critical care unit diary intervention26 and a clinical psychology intervention27 have been shown to have an effect on longer-term psychological outcomes. Outside the critical care unit setting, cognitive–behavioural therapy (CBT) techniques have been found to be effective in reducing symptoms of stress in patients with mental or physical illness, mitigating hallucinations and delusions in mental health settings and in reducing PTSD symptoms.21,22,28–39

Research suggests that post discharge (e.g. at 6 weeks40 or at outpatient follow-up clinics41) may be too late to provide psychological interventions for critical care unit survivors, and that earlier intervention could be more beneficial in preventing longer-term psychological morbidity. For example, a clinical psychology study27 indicated that considerably fewer individuals reported experiencing PTSD, depression or anxiety one year after their critical care unit stay when they had received interventions by practitioner psychologists while in the critical care unit. However, this study27 did not specify or standardise the interventions that patients received and was not a randomised clinical trial (RCT). The diary intervention was effective in reducing the proportion of patients with PTSD at 3 months in a RCT, but it retrospectively targets factual memory gaps rather than acute stress. Although diaries are written by nurses and/or relatives in the unit, it is not an early intervention because patients receive the diaries at varying time points after discharge.

Very few NHS critical care units have regular access to psychologists as part of their multidisciplinary critical care team (because of resource and other constraints). Acknowledging this and the evidence indicating that non-experts can be trained to deliver effective psychological interventions in other settings [i.e. studies have evaluated CBT techniques as effective when delivered by non-expert staff (including nurses) to patients with psychosis in mental health settings], we developed a preventive, complex psychological intervention to be led by specially trained nurses, who were selected by local critical care units.30,31,42–44

To develop the preventive, complex psychological intervention, previously, members of the team, led by the lead adult critical care health psychologist (DW), followed stage one of the Medical Research Council (MRC) framework (see Appendix 1) to guide researchers to develop and evaluate complex interventions.45 Stage one involved three steps, which were to:

1. Identify the evidence base for an intervention to reduce patients’ acute stress.
2. Develop a theoretical understanding of the likely process of change in reducing stress.
3. Model the process to progressively refine the intervention.

Evidence was reviewed to inform the team’s understanding of the determinants of acute stress in critical care patients, and the likely mechanisms of change involved in reducing acute stress. We carried out a systematic review of psychosocial interventions to reduce acute or long-term stress of critical care patients (step one).46 The results46 indicated that interventions such as music, massage, relaxation and psychology sessions in critical care reduced acute or long-term stress in 12 out of 23 studies. To develop a theoretical understanding of the likely process of change, we conducted quantitative and qualitative research (Dr Dorothy Wade, University College London Hospitals NHS Foundation Trust, 4 July 2019, personal communication)14,19,47 with patients and nurses to learn about their experiences of managing patients’ stress, and applied existing health psychology theories of stress, health and coping, and clinical psychology theories of psychosis and post-traumatic stress (step two).48–50

Based on steps one and two, we hypothesised that an early intervention, commencing while in the critical care unit and combining evidence-based psychological techniques from CBT for psychosis and trauma and coping strategies such as relaxation, meditation and music, could help alleviate acute stress and the development of longer-term psychological morbidity. We adapted techniques from CBT that have been found to be effective in other populations and settings in reducing acute stress, lessening the impact of hallucinations and delusions, and preventing post-traumatic stress, to the critical care setting. The intervention was modelled (step 3) with critical care patients by a health psychologist and senior nurses in one unit, in consultation with former patients and experts in health and clinical psychology, PTSD and psychosis. This was an iterative process to progressively refine the intervention.

The outcome of this process was the development of an early, nurse-led, preventive complex psychological intervention with the aim of alleviating acute stress and the development of longer-term psychological morbidity in critical care patients. The intervention comprised three elements:

1. creating a therapeutic environment in critical care
2. three stress support sessions for patients identified as acutely stressed
3. a relaxation and recovery programme for patients identified as acutely stressed.

Aim

The overall aims of the Psychological Outcomes following a nurse-led Preventative Psychological Intervention for critically ill patients (POPPI) study were to produce a standardised preventive, complex psychological intervention (the ‘POPPI intervention’) and, if deemed feasible, evaluate whether or not it is beneficial to critically ill patients and the NHS in terms of clinical effectiveness and cost-effectiveness.

Objectives

The POPPI study consisted of two phases: (1) a standardisation and feasibility phase and, if deemed feasible, (2) a cluster RCT. The overall objectives were to:

• standardise the preventive, complex psychological intervention
• develop an education package and support tools to deliver the intervention
• test the feasibility and acceptability of the education package, support tools and delivery of the intervention to patients and staff (i.e. the intervention feasibility study)
• refine the education package, support tools and intervention based on results of the intervention feasibility study
• test the feasibility of the proposed procedures for the cluster RCT (i.e. the RCT procedures feasibility study)
• evaluate, using a parallel-group cluster RCT design, the clinical effectiveness and cost-effectiveness of the intervention, including an integrated process evaluation (if deemed feasible).