Resuscitation 85 (2014) 454–455
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Characterising early recovery in survivors of cardiac arrest
In this issue of the journal is a paper reporting a prospective observational study aiming to describe changes in functional outcome following cardiac arrest with subsequent return of spontaneous circulation and therapeutic hypothermia.1 The authors chose to look for any change occurring in the period between discharge from intensive care and 1 and 6 months after this. Additional aims were to describe activities of daily living, cognitive function and life satisfaction during this period. Their choice of time interval and study instruments are of particular interest. Previous work has focussed predominantly on outcomes in the 3 month to 2-year time frame. The authors’ choice to describe functional outcome at this much earlier stage is noteworthy. This multi-centre study included those still comatose following return of spontaneous circulation but excluded those with signiﬁcant haemodynamic instability at 5 min after return of spontaneous circulation; it also excluded those who were pregnant, had terminal illness, deranged clotting and under the age of 18 at the time of admission. Whilst nearly 50% (62/125) of those who were successfully cooled and remained in the same facility as the admitting ICU died, mortality after discharge from hospital was a modest further 3% (2/63) of the discharged population over 6 months. Despite this seemingly low mortality, 25% (16/63) of the hospital survivors were lost to follow-up because of communication problems at either or both time points. Despite these losses, a response rate of 72% (45/63) at both time points is certainly respectable. However, 14% (9/63) of the survivor population were able to respond at only one of the two time points. The reasons for this are not clear but may highlight an improving trend during this period or alternatively may reﬂect inability to engage with the study instruments this early. Unlike many other larger studies a visiting study manager made the assessment of Cerebral Performance Category, Activities of Daily Living, Mini Mental State Examination and LiSat-11 at 1 and 6 months. Whilst we have no detail of their training or the exact format in which the interview took place, a visit from a study member should be considered close to the gold standard. However, as pointed out by the authors themselves many of the instruments do require intact mental and physical abilities in order to take part. The population captured appears broadly consistent with the general cardiac arrest population with the majority being retired, male, experiencing VF/VT and having a history of heart disease prior to cardiac arrest. Half of the 22% of patients who were working full time prior to the event returned to work by 6 months, with a corresponding rise in those retired or on sick leave. What is most striking is that 18% of survivors at six months are still in full or part-time employment and although the results are not broken down into socio-economic sub groups we can only presume these represent both the younger and the least impaired patients. 0300-9572/$ – see front matter © 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.resuscitation.2014.01.021
The apparent limitations of this study lie predominantly in the relatively small group of survivors and the losses to follow up. Despite the authors’ intention to include patients regardless of their CPC score, those patients lost during follow-up included all the patients with a cerebral performance score of 3 or 4. A recent review by Sandroni et al. notes that whilst the majority of existing trial data is of poor quality, outcome evaluation undertaken too early may overestimate the number of patients assigned CPC 32 as further recovery may occur in some. We must therefore accept when interpreting the results of this study that patients with early signiﬁcant and potentially reversible impairment may have been over scored or excluded (by impairment) completely from the results presented here. Regardless of whether they achieved this aim or not, the data do still have merit. Pragmatically speaking this study describes the functional status of those patients that could be reasonably engaged outside of the hospital for early rehabilitation interventions. However, the authors have also described a high engagement with the health care system during the 1–6 month period following discharge from hospital. Whilst this is not expanded upon, 60% of survivors had some form of contact with the health care system and of these nearly half had required an admission to hospital. A signiﬁcant proportion of these admissions appears to be due to the installation of an Implantable Cardioverter Deﬁbrillator, recurrent cardiac symptoms and respiratory disease. This could represent a major challenge for future interventions in this early time window. Follow-up is therefore occurring during the initial phases of recovery and at a very busy time for the patient. It is worth noting that only the minority of patients lost to follow-up opted out. Instead the majority were unable to effectively communicate or take part in the assessment process. These patients represent a discrete population who are currently unclassiﬁed in terms of their functional status who may go on to recover. Thus future work may wish to study those who will ultimately recover further function and in whom early intervention may well also be beneﬁcial. One major utility of early data such as these is it allows us to understand the initial stages of recovery. Understanding early characteristics, which may predict future poor recovery, is crucial as this may help us identify populations likely to beneﬁt from interventions. In critical care we have “learned” repeatedly that all-comers interventional trials struggle to demonstrate beneﬁt. Where it is possible to enrich study populations with those with a greater a priori chance of beneﬁt, things may be different. This is well demonstrated by the study of the provision of diaries for intensive care survivors published by Jones and colleagues3 ; the greatest beneﬁt was demonstrated in patients who manifested clear, early signs of psychological distress. In the general intensive care population, detailed studies such as that of Wade and colleagues,4 with low
Editorial / Resuscitation 85 (2014) 454–455
levels of drop out and detailed early and longitudinal phenotyping are providing crucial background – but it has taken us a while to learn how to perform these studies. Each time we extend our enquiries, we start off with small steps – in some circumstances, we may need many small steps; this study may be one such step. Conﬂict of interest statement No conﬂicts of interest to declare. References 1. Walin E, Larsson I-M, Rubertsson S, Kristofferzon M-L. Cardiac arrest and hypothermia treatment-function and life satisfaction among survivors in the ﬁrst 6 months. Resuscitation 2014;85:538–43. 2. Sandroni C, Cavallaro F, Callaway CW, et al. Predictors of poor neurological outcome in adult comatose survivors of cardiac arrest: a systematic review and meta-analysis. Part 1: Patients not treated with therapeutic hypothermia. Resuscitation 2013;84:1324–38. 3. Jones C, Bäckman C, Capuzzo M, et al. Intensive care diaries reduce new onset post traumatic stress disorder following critical illness: a randomised, controlled trial. Crit Care 2010;14:R168.
4. Wade DM, Howell DC, Weinman JA, et al. Investigating risk factors for psychological morbidity three months after intensive care: a prospective cohort study. Crit Care 2012;16:R192.
Stephen Brett ∗ Centre for Perioperative Medicine and Critical Care Research, Imperial College Healthcare NHS Trust, United Kingdom Robert Hatch John Radcliffe Hospital, Oxford University Hospitals NHS Trust, United Kingdom ∗ Corresponding author at: Imperial College Healthcare NHS Trust, London, United Kingdom. E-mail address: [email protected]
24 January 2014