Timing and burden of persistent critical illnessin UK intensive care units: An observational cohort study

Background Persistent critical illness is a recognisable clinical syndrome defined conceptually as when the patient’s reason for being in the intensive care unit (ICU) is more related to their ongoing critical illness than their original reason for admission. Our objectives were: (1) to assess the day in ICU on which chronic factors (e.g., age, gender and comorbidities) were more predictive of survival than acute factors (e.g. admission diagnosis, physiological derangements) measured on the day of admission; (2) to assess the consistency of this finding across major patient subgroups and over time and (3) to compare case mix characteristics and outcomes for patients determined to develop persistent critical illness (based on ICU length of stay) with other patients. Methods Observational cohort study using a high-quality clinical database from the national clinical audit of adult critical care. 217 adult ICUs in England, Wales and Northern Ireland. 835,946 adult patients admitted to participating ICUs between 1 April 2009 and 31 March 2016. The main outcome measure was mortality at discharge from acute hospital. Results We fitted two statistical models (‘chronic’ and ‘acute’) and updated these based upon patients with an ICU length of stay of at least 1, 2, etc., up to 28 days. The discrimination of the chronic model first exceeded that of the acute model on day 11. Patients with longer stays (>10 days) comprised 9% of admissions but used 45% of ICU bed-days. After a mean ICU length of stay of 22 days and a subsequent 28 days in hospital, 30% died. Conclusions Persistent critical illness is commonly encountered in clinical practice and is associated with increased healthcare utilisation and adverse outcomes. Improvements in our understanding of the longer term outcomes and in the development of tools to aid prognostication are urgently required – for humane as well as health economic reasons.

Nature and impact of in-hospital complications associated with persistent critical illness

Background: Persistent critical illness (PerCI) is defined as an intensive care unit (ICU) admission lasting  10 days. The in-hospital complications associated with its development are poorly understood. Aims: To test whether PerCI is associated with a greater prevalence, rate and specific types of in-hospital complications. Methods: Single-centre, retrospective, observational case–control study. Results: We studied 1200 patients admitted to a tertiary ICU from 2010 to 2015. Median ICU length of stay was 16 days (interquartile range [IQR], 12–23) for PerCI patients v 2.3 days (IQR, 1.1–3.7) for controls, and median hospital length of stay was 41 days (IQR, 22–75) v 8 days (IQR, 4–17) respectively. A greater proportion of PerCI patients received acute renal replacement therapy (37% v 6.8%) or underwent reintubation (17% v 1%) and/or tracheostomy (36% v 0.6%); P < 0.0001. Despite these complications, PerCI patients had similar hospital mortality (29% v 27%; P = 0.53). PerCI patients experienced a greater absolute number of complications (12.1 v 4.0 complications per patient; P < 0.0001) but had fewer exposure-adjusted complications (202 v 272 complications per 1000 hospital bed-days; P < 0.001) and a particularly high overall prevalence of specific complications. Conclusions: PerCI patients experience a higher prevalence, but not a higher rate, of exposure-adjusted complications. Some of these complications appear amenable to prevention, helping to define intervention targets in patients at risk of PerCI. Funding: Austin Hospital Intensive Care Trust Fund.

Metabolic and endocrine changes in acute and chronic critical illness

Critical illness, an extreme form of severe physical stress, is characterized by important endocrine and metabolic changes. The development of critical care medicine has made possible survival from conditions that were previously rapidly fatel, and as a result many patients now enter a prolonged phase of chronic or persistent critical illness. Acute endocrine adaptations are directed towards providing energy and substrates for the vital fight or flight response in the context of exogenous substrate deprivation. Distinct endocrine and metabolic alterations characterize the chronic phase of critical illness, which seems to no longer be solely beneficial and may hamper recovery and rehabilitation. Onset of the stressful event causes an acute activation of pulsatile hormonal release from the anterior pituitary, followed by suppression in the chronic phase of illness, ultimately resolving to normality if recovery occurs.