Post-intensive care syndrome (PICS) describes a collection of symptoms related to physical, psychosocial, and cognitive health and function that are new or worsened in patients who survive critical illness (e.g., severe infection, heart attack, cardiac arrest, stroke, etc.) and/or life-threatening traumatic injuries and admission to intensive care. The range of symptoms that PICS describes falls under three broad categories: physical impairment, cognitive impairment, and psychiatric impairment. A person with PICS may have symptoms from one or multiple of these categories. Additionally, family members are also simultaneously affected by their loved ones' intensive care unit (ICU) experience and caregiving for them afterwards. This has been recognized as post-intensive care syndrome-family (PICS-F).
Improvements in survival after a critical illness have led to research focused on long-term outcomes for these patients. This improved survival has also led to the discovery of significant functional disabilities that many survivors of critical illness experience. Because the majority of literature in critical care medicine is focused on short-term outcomes (e.g. survival), the current understanding of PICS is relatively limited. Recent research suggests that there is significant overlap among the three broad categories of symptoms. Also, sedation and prolonged immobilization seem to be common themes among patients who have PICS.
The term PICS arose around 2010, at least in part, to raise awareness of the important long-term dysfunctions resulting from treatment in the intensive care unit (ICU). Awareness of these long-term functional disabilities is growing, and research is ongoing to further clarify the spectrum of disabilities and to find more effective ways to prevent these long-term complications and to more effectively treat functional recovery. Increased awareness in the medical community has also highlighted the need for more hospital and community-based resources to more effectively identify and treat patients with PICS after surviving a critical illness.
Grouping these impairments together within a syndrome was done to increase awareness of post-critical illness issues. However, an updated definition was required to accommodate new knowledge on PICS. A current and holistic definition of PICS is the new or worsening impairment to the physical, mental, cognitive, employment, and/or social domains of health following critical illness. These five impairments are the defining characteristics of PICS.
Origins Before the term PICS was created, there was recognition of the ramifications of critical illness. In 1892, Osler was the first to note the "rapid loss of flesh", or muscle wasting, in patients with prolonged sepsis (Osler, 1892, as cited in Jolley et al., 2016, p. 1129). In 1998, researchers found that critically ill patients experienced poorer mental health and more post-traumatic stress disorder (PTSD) symptoms, than non-critically ill patients. In 1999, it was discovered many survivors of critical illness had cognitive impairments. As research on the impairment to physical, mental, and cognitive health resulting from critical illness accumulated, the significance and relationship of these long-term issues was recognized. This resulted in the 2010 multidisciplinary conference where the term PICS was created. The impairments to physical, mental, and cognitive health grouped within PICS increased awareness, research, and education on consequences observed in survivors of critical illness.
As intended, PICS research continued and additional impairments became evident. In the 2010s, researchers noted social dysfunction in survivors of critical illness. Impaired employment following critical illness has appeared in the literature since 1995. However, the recognition that unemployment due to critical illness can negatively affect well-being and quality of life, is a recent finding. Despite the evidence of impairment to employment and social health following critical illness, there has been a reluctance to include these impairments within the PICS definition. This demonstrates the original PICS definition is outdated and overly focused on the biomedical model of health. In order to care for PICS, clinicians and researchers need to recognize all impairments experienced by survivors of critical illness. Using a holistic perspective, these social and employment impairments can be recognized within PICS and attended to appropriately.
Conditions The most recognized form of the syndrome is the physical dysfunction commonly known as ICU-acquired weakness. The other physical, cognitive, and mental health impairments are less well recognized and need further research to be better understood.
Physical impairment ICU-acquired weakness (ICU-AW), sometimes called critical illness polyneuropathy, is the most common form of physical impairment, and is estimated to occur in 25 percent or more of ICU survivors. It is thought to be an effect of long-term immobility and deep sedation that many critically ill patients experience while in the ICU. In addition, severe infections and inflammation are significant risk factors for developing ICU-AW.Prevention CfDCa. Critical Illness Polyneuropathy Critical Illness Myopathy. Centers for Disease Control and Prevention.
ICU-AW often presents as difficulty performing activities of daily living (e.g. moving around the living environment, using the bathroom, ability to make meals or do laundry). Inability to effectively perform these tasks can be particularly distressing to patients. The deficits associated with ICU-AW have a direct and negative effect on a person's independence. The natural course of ICU-AW is variable, but some patients recover within a year.
Other physical impairments include joint contractures due to long periods of immobility while hospitalized. The elbow and ankle are the most commonly affected joints, followed by the hip and knee. Some physical weakness may result from malnutrition during critical illness. Though nutrition may be provided by tube-feeding or parenteral nutrition, the initiation of parenteral nutrition may be delayed, and interruptions in feeding often occur due to gastrointestinal intolerance or the performance of procedures that require an empty stomach. In people who experience acute respiratory distress syndrome and are treated with mechanical ventilation, lung function is often compromised for months to years. The most commonly impaired lung function is diffusing capacity for carbon monoxide, as well as reduced lung volumes and spirometry.
Cognitive impairment Cognitive impairments include deficits in memory, attention, mental processing speed, and problem-solving. These impairments affect up to 80% of individuals who survive a critical illness.Group IDaCIS. ICU Delirium and Cognitive Impairment Study Group. ICU Delirium and Cognitive Impairment Study Group http://www.icudelirium.org/. Impairments in memory and executive function have the most profound effect in terms of prohibiting people from engaging in the tasks and behaviors needed to function effectively in daily life and carry out complex cognition. The effect of cognitive dysfunction is significant – unemployment is not uncommon because of difficulties with tasks of executive function (e.g. completing regular tasks like balancing a checkbook, and remembering facts or events). Among individuals with PICS-associated cognitive impairments, most patients improve or completely resolve over the first year.
Major risk factors for cognitive impairment following ICU admission due to critical illness include delirium, prior cognitive deficit, sepsis, and acute respiratory distress syndrome (ARDS). It is currently believed that many factors can play a role in causing cognitive impairment following critical illness. Some possible mechanisms for include poor blood supply to the brain due to low blood pressure from sepsis, poor oxygen supply to the brain due to respiratory distress and impairment, inflammation of the brain, and disruption of the blood–brain barrier in the areas of the brain that are involved in executive function and memory.
Psychiatric impairment Depression and anxiety are the two most common mental health disorders seen in individuals with PICS. The range of possible mental health problems, however, is far wider. Dementia, post-traumatic stress disorder (PTSD), and persistent delusional behavior are also manifestations of the syndrome. Although not completely understood, the anxiety and delusions seen in patients with PICS are likely linked to delusional memories that some individuals acquire during their stay in the ICU, rather than recall of factual memories. It is thought that medically induced sedation may contribute to the formation of delusional memories by raising the risk of delirium and hallucinations.
Risk factors are similar to those for cognitive impairment following critical illness, and include severe sepsis, acute respiratory distress syndrome, respiratory failure, trauma, hypoglycemia, and hypoxemia. Like ICU-acquired weakness, long-term immobility and deep sedation have been known to play an important part in the development of mental health problems seen in PICS. Sleep pattern disturbance, a common problem in the ICU, is also a likely culprit. Lower education level, pre-existing disability, alcohol use disorder, pre-existing anxiety, depression, and PTSD are also risk factors for PICS-related mental health disorders. Contrary to earlier believes, neither age nor sex have shown to be risk factors for either depressive states or anxiety. The estimated prevalence of mental disorders after intensive care varies. Meta analyses have shown a prevalence for depressive symptoms after intensive care between 4%-64%, and between 5%-73% for anxiety. The fact that papers often uses different methods to estimate prevalence on mental disorders after intensive care, i.e. different types of self reporting forms, diagnose codes, and different time points at data collection is a big contributor to the big variety in prevalence estimation.
The natural history for mental health disorders following critical illness is not well known, likely due to lack of recognition that these psychiatric symptoms may be related to a remote ICU admission. With proper psychological and psychiatric help, mental illness related to PICS can be successfully managed, but research favors preventative strategies as the most effective management. While there are ongoing studies focused on determining the best way to treat and prevent psychiatric problems following critical illness, daily diaries, so-called "ICU diaries" seem to be the most promising. These ICU diaries appear to be effective in treating the delusional, false memories that some of these individuals develop. Healthcare providers, especially clinical social workers who specialize in medical care, can be very helpful in advocating these practices and facilitating them for patients and families.
Social impairment Social impairment in PICS is a negative change to a patient's social health. This is exhibited in people living with PICS as avoiding socialization, loss of previous social roles, reduced social confidence, or perceiving themselves as a social burden. Despite recognition of this impairment in research, many authors omit social impairment from the PICS definition. Without recognition of these impairments, critical care survivors may not be provided with education, resources, and support regarding new PICS social dysfunctions
Employment impairment