Aerobic exercise capacity in long-term survivors of critical illness: secondary analysis of the post-EPaNIC follow-up study

Interpretation of cardiopulmonary exercise test by GPT - promising tool as a first step to identify normal results

BACKGROUND

Cardiopulmonary exercise testing (CPET) is used in the evaluation of unexplained dyspnea. However, its interpretation requires expertise that is often not available. We aim to evaluate the utility of ChatGPT (GPT) in interpreting CPET results.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 150 patients who underwent CPET. Two expert pulmonologists categorized the results as normal or abnormal (cardiovascular, pulmonary, or other exercise limitations), being the gold standard. GPT versions 3.5 (GPT-3.5) and 4 (GPT-4) analyzed the same data using pre-defined structured inputs.

RESULTS

GPT-3.5 correctly interpreted 67% of the cases. It achieved a sensitivity of 75% and specificity of 98% in identifying normal CPET results. GPT-3.5 had varying results for abnormal CPET tests, depending on the limiting etiology. In contrast, GPT-4 demonstrated improvements in interpreting abnormal tests, with sensitivities of 83% and 92% for respiratory and cardiovascular limitations, respectively. Combining the normal CPET interpretations by both AI models resulted in 91% sensitivity and 98% specificity. Low work rate and peak oxygen consumption were independent predictors for inaccurate interpretations.

CONCLUSIONS

Both GPT-3.5 and GPT-4 succeeded in ruling out abnormal CPET results. This tool could be utilized to differentiate between normal and abnormal results.

Exploring Peripheral and Respiratory Muscle Weakness and Functional Impairments in ICU Patients: Insights From a Resource-Constrained Setting

IMPORTANCE AND OBJECTIVES

The aim of this study was to explore peripheral and respiratory muscle structure and strength from unit admission to hospital discharge among ICU patients in a resource-constrained setting.

DESIGN

Prospective, observational study.

SETTING

Tertiary academic hospital.

PARTICIPANTS

Newly intubated critically ill adults admitted to the medical and surgical ICUs and expected to be mechanically ventilated for more than 48 hours were included in the study.

MAIN OUTCOMES AND MEASURES

Ultrasonography of the right hemi-diaphragm and quadriceps muscles were taken at admission for 3 consecutive days. Respiratory and peripheral muscle strength were evaluated using the Medical Research Council-Sum Score, dynamometry and maximal inspiratory pressure (MIP) at awakening, ICU discharge and hospital discharge.

RESULTS

Forty-five participants were included, with a median (interquartile range) age of 34.5 (24.3-47.4) years and 73% were male. Most of the change in diaphragm thickness was observed on day 3, with 5 (22%) participants showing a decrease of more than 10% from baseline. Minimal changes in rectus femoris cross-sectional area were noted during the first 3 days. Eleven participants (44%) presented with ICU-acquired weakness at awakening, which decreased to 7 (29%) participants at ICU discharge and 5 (24%) participants at hospital discharge. The mean ± sd percentage of predicted quadriceps force was 22.2 ± 5.1 N at hospital discharge. The mean ± sd percentage of predicted MIP scores was 29.6% ± 10.5% at ICU discharge and 29.1% ± 8.6% at hospital discharge.

CONCLUSIONS AND RELEVANCE

Patients discharged from the ICU in a resource-constrained setting presented with peripheral and respiratory muscle weakness, with minimal change in muscle structure shown by ultrasonography, despite short ICU stays, low Acute Physiology and Chronic Health Evaluation II scores, and a relatively young age. Future research should explore whether these findings indicate a distinct phenotype of critical illness in such environments.

Muscle Dysfunction and Physical Recovery After Critical Illness

During critical illness, patients experience significant and rapid onsets of muscle wasting and dysfunction with loss of strength, mass, and power. These deficits often persist long after the ICU, leading to impairments in physical function including reduced exercise capacity and increased frailty and disability. While there are numerous studies describing the epidemiology of impaired muscle and physical function in the ICU, there are significantly fewer data investigating mechanisms of prolonged and persistent impairments in ICU survivors. Additionally, while several potential clinical risk factors associated with poor physical recovery have been identified, there remains a dearth of interventions that have effectively improved outcomes long-term among survivors. In this article, we aim to provide a thorough, evidence-based review of the current state of knowledge regarding muscle dysfunction and physical function after critical illness with a focus on post-ICU and post-hospitalization phase of recovery.

Survivorship After Cardiogenic Shock

Advances in critical care therapies for patients with cardiogenic shock (CS), including temporary mechanical circulatory support and multidisciplinary shock teams, have led to improved survival to hospital discharge, ranging from 60% to 70%. After their index hospitalization, however, survivors of CS may continue to face cardiac as well as extracardiac sequelae of these therapies and complications for years to come. Most studies in CS have focused primarily on survival, with limited data on long-term recovery measures among survivors. In other forms of critical illness, research indicates that many intensive care unit survivors experience impairments in multiple domains, such as cognitive function, physical ability, and mental health. These impairments, collectively referred to as Post-Intensive Care Syndrome, in turn impact survivors' quality of life and future prognosis. This review identifies unique aspects of CS-related survivorship, highlights lessons learned from other forms of critical illness, and outlines future research directions to determine specific strategies to enhance recovery and survivorship after CS.

Post-Intensive Care Syndrome as a Burden for Patients and Their Caregivers: A Narrative Review

Millions of critically ill patients are discharged from intensive care units (ICUs) every year. These ICU survivors may suffer from a condition known as post-intensive care syndrome (PICS) which includes a wide range of cognitive, psychological, and physical impairments. This article will provide an extensive review of PICS. ICU survivors may experience cognitive deficits in memory and attention, with a slow-down of mental processing and problem-solving. From psychological perspectives, depression, anxiety, and post-traumatic stress disorder are the most common issues suffered after ICU discharge. These psycho-cognitive impairments might be coupled with ICU-acquired weakness (polyneuropathy and/or myopathy), further reducing the quality of life, the ability to return to work, and other daily activities. The burden of ICU survivors extends to families too, leading to the so-called PICS-family (or PICS-F), which entails the psychological impairments suffered by the family and, in particular, by the caregiver of the ICU survivor. The development of PICS (and PICS-F) is likely multifactorial, and both patient- and ICU-related factors may influence it. Whilst the prevention of PICS is complex, it is important to identify the patients at higher risk of PICS, and clinicians should be aware of the tools available for diagnosis. Stakeholders should implement strategies to achieve PICS prevention and to support its effective treatment during the recovery phase with dedicated pathways and supporting care.

Using augmented intelligence to improve long term outcomes

PURPOSE OF REVIEW

For augmented intelligence (AI) tools to realize their potential, critical care clinicians must ensure they are designed to improve long-term outcomes. This overview is intended to align professionals with the state-of-the art of AI.

RECENT FINDINGS

Many AI tools are undergoing preliminary assessment of their ability to support the care of survivors and their caregivers at multiple time points after intensive care unit (ICU) discharge. The domains being studied include early identification of deterioration (physiological, mental), management of impaired physical functioning, pain, sleep and sexual dysfunction, improving nutrition and communication, and screening and treatment of cognitive impairment and mental health disorders.Several technologies are already being marketed and many more are in various stages of development. These technologies mostly still require clinical trials outcome testing. However, lacking a formal regulatory approval process, some are already in use.

SUMMARY

Plans for long-term management of ICU survivors must account for the development of a holistic follow-up system that incorporates AI across multiple platforms. A tiered post-ICU screening program may be established wherein AI tools managed by ICU follow-up clinics provide appropriate assistance without human intervention in cases with less pathology and refer severe cases to expert treatment.

Physical function measures in ICU survivors, where to now? A scoping review

Background

Growing evidence is describing the long-term morbidity experienced by critical illness survivors, a major contributing factor being impaired physical function. Consensus is yet to be reached on which physical function measures should be included in this population. This review aimed to describe physical functioning measurement instruments used in longitudinal studies of critical illness survivors, based on the International Classification of Function (ICF).

Methods

An electronic database search of EbscoHost, Web of Science and Scopus was conducted from inception to November 2023. Two reviewers independently applied the inclusion and exclusion criteria to titles, abstracts and full text-studies. Extracted data included year of publication; country; participant age; follow-up timeframes and physical measurement instruments used. Instruments were classified according to ICF domains.

Results

Eighty studies published between 1995 and November 2023 were included. Forty-four different outcome measures were identified. Most studies (68) included multiple followed-up points and were completed within a year, and few studies (12) follow-up beyond a year. Based on the ICF, 11 (25%) instruments measured impairments and 33 (75%) activity limitations. Muscle power functions were the most frequently measured impairment (65%), utilising manual muscle testing (37.3%). The six-minute walk test (6MWT) was the most frequently used instrument in the activity/participation domain (31.6%). Only one instrument addressed all five the physical activity/participation domains, while the majority focused on mobility domain.

Conclusion

Multiple tools are used to report on physical deficits experienced by ICU survivors, either measuring impairments or activity/ participation limitations. Most studies report on physical function within the first year of survival. The heterogeneity and inconsistency over time of instruments used prevents synthesis of data to determine intervention efficacy. The validity, predictive value and sensitivity of the reported measures within ICU survivors needs to be established, only then can intervention studies be designed to measure effectiveness.

Contribution of the study

This scoping review contributes to the existing literature and development of standardised core outcome measure sets (COMS) for critical illness research by providing a comprehensive and systematic mapping of physical function measurement instruments utilised in longitudinal studies of critical illness survivors. By categorising these instruments according to the International Classification of Functioning, Disability and Health (ICF) framework, the review offers a novel perspective on the current state of outcome measurement in this field.

Identifying limitations to exercise with incremental cardiopulmonary exercise testing: a scoping review

Cardiopulmonary exercise testing (CPET) is a comprehensive and invaluable assessment used to identify the mechanisms that limit exercise capacity. However, its interpretation remains poorly standardised. This scoping review aims to investigate which limitations to exercise are differentiated by the use of incremental CPET in literature and which criteria are used to identify them. We performed a systematic, electronic literature search of PubMed, Embase, Cochrane CENTRAL, Web of Science and Scopus. All types of publications that reported identification criteria for at least one limitation to exercise based on clinical parameters and CPET variables were eligible for inclusion. 86 publications were included, of which 57 were primary literature and 29 were secondary literature. In general, at the level of the cardiovascular system, a distinction was often made between a normal physiological limitation and a pathological one. Within the respiratory system, ventilatory limitation, commonly identified by a low breathing reserve, and gas exchange limitation, mostly identified by a high minute ventilation/carbon dioxide production slope and/or oxygen desaturation, were often described. Multiple terms were used to describe a limitation in the peripheral muscle, but all variables used to identify this limitation lacked specificity. Deconditioning was a frequently mentioned exercise limiting factor, but there was no consensus on how to identify it through CPET. There is large heterogeneity in the terminology, the classification and the identification criteria of limitations to exercise that are distinguished using incremental CPET. Standardising the interpretation of CPET is essential to establish an objective and consistent framework.

Hemodynamic Melody of Postnatal Cardiac and Pulmonary Development in Children with Congenital Heart Diseases

Hemodynamics is the eternal theme of the circulatory system. Abnormal hemodynamics and cardiac and pulmonary development intertwine to form the most important features of children with congenital heart diseases (CHDs), thus determining these children's long-term quality of life. Here, we review the varieties of hemodynamic abnormalities that exist in children with CHDs, the recently developed neonatal rodent models of CHDs, and the inspirations these models have brought us in the areas of cardiomyocyte proliferation and maturation, as well as in alveolar development. Furthermore, current limitations, future directions, and clinical decision making based on these inspirations are highlighted. Understanding how CHD-associated hemodynamic scenarios shape postnatal heart and lung development may provide a novel path to improving the long-term quality of life of children with CHDs, transplantation of stem cell-derived cardiomyocytes, and cardiac regeneration.

Protein and energy intake in intensive care unit survivors during the first year of recovery: A descriptive cohort study

BACKGROUND

Many intensive care unit (ICU) survivors suffer long-term health issues that affect their quality of life. Nutrition inadequacy can limit their rehabilitation potential. This study investigates nutrition intake and support during ICU admission and recovery.

METHODS

In this prospective cohort study, 81 adult ICU patients with stays ≥48 h were included. Data on dietary intake, feeding strategies, baseline and ICU characteristics, and 1-year outcomes (physical health and readmission rates) were collected. The number of patients achieving 1.2 gram per kilogram per day of protein and 25 kilocalories per kilogram per day at 3 months, 6 months, and 12 months after ICU admission was recorded. The impact of dietary supplementation during the year was assessed. Baseline characteristics, intake barriers, and rehabilitation's influence on nutrition intake at 12 months were evaluated, along with the effect of inadequate intake on outcomes.

RESULTS

After 12 months, only 10% of 60 patients achieved 1.2 g/kg/day protein intake, whereas 28% reached the advised 25 kcal/kg/day energy target. Supplementary feeding significantly increased protein intake at 3, 6, and 12 months (P = 0.003, P = 0.012, and P = 0.033, respectively) and energy intake at 3 months (P = 0.003). A positive relation was found between female sex and energy intake at 12 months after ICU admission (β = 4.145; P = 0.043) and taste issues were independently associated with higher protein intake (β = 0.363; P = 0.036). However, achieving upper-quartile protein or energy intake did not translate into improved physical health outcomes.

CONCLUSION

Continuous and improved nutrition care is urgently needed to support patients in reaching nutrition adequacy.

Illness Weakness, Polyneuropathy and Myopathy: Diagnosis, treatment, and long-term outcomes

BACKGROUND

Severe weakness associated with critical illness (CIW) is common. This narrative review summarizes the latest scientific insights and proposes a guide for clinicians to optimize the diagnosis and management of the CIW during the various stages of the disease from the ICU to the community stage.

MAIN BODY

CIW arises as diffuse, symmetrical weakness after ICU admission, which is an important differentiating factor from other diseases causing non-symmetrical muscle weakness or paralysis. In patients with adequate cognitive function, CIW can be easily diagnosed at the bedside using manual muscle testing, which should be routinely conducted until ICU discharge. In patients with delirium or coma or those with prolonged, severe weakness, specific neurophysiological investigations and, in selected cases, muscle biopsy are recommended. With these exams, CIW can be differentiated into critical illness polyneuropathy or myopathy, which often coexist. On the general ward, CIW is seen in patients with prolonged previous ICU treatment, or in those developing a new sepsis. Respiratory muscle weakness can cause neuromuscular respiratory failure, which needs prompt recognition and rapid treatment to avoid life-threatening situations. Active rehabilitation should be reassessed and tailored to the new patient's condition to reduce the risk of disease progression. CIW is associated with long-term physical, cognitive and mental impairments, which emphasizes the need for a multidisciplinary model of care. Follow-up clinics for patients surviving critical illness may serve this purpose by providing direct clinical support to patients, managing referrals to other specialists and general practitioners, and serving as a platform for research to describe the natural history of post-intensive care syndrome and to identify new therapeutic interventions. This surveillance should include an assessment of the activities of daily living, mood, and functional mobility. Finally, nutritional status should be longitudinally assessed in all ICU survivors and incorporated into a patient-centered nutritional approach guided by a dietician.

CONCLUSIONS

Early ICU mobilization combined with the best evidence-based ICU practices can effectively reduce short-term weakness. Multi-professional collaborations are needed to guarantee a multi-dimensional evaluation and unitary community care programs for survivors of critical illnesses.

Sex-differences in the longitudinal recovery of neuromuscular function in COVID-19 associated acute respiratory distress syndrome survivors

Introduction

Patients admitted to the intensive care unit (ICU) following severe acute respiratory syndrome 2 (SARS-CoV-2) infection may have muscle weakness up to 1 year or more following ICU discharge. However, females show greater muscle weakness than males, indicating greater neuromuscular impairment. The objective of this work was to assess sex differences in longitudinal physical functioning following ICU discharge for SARS-CoV-2 infection.

Methods

We performed longitudinal assessment of physical functioning in two groups: 14 participants (7 males, 7 females) in the 3-to-6 month and 28 participants (14 males, 14 females) in the 6-to-12 month group following ICU discharge and assessed differences between the sexes. We examined self-reported fatigue, physical functioning, compound muscle action potential (CMAP) amplitude, maximal strength, and the neural drive to the tibialis anterior muscle.

Results

We found no sex differences in the assessed parameters in the 3-to-6-month follow-up, indicating significant weakness in both sexes.Sex differences emerged in the 6-to-12-month follow-up. Specifically, females exhibited greater impairments in physical functioning, including lower strength, walking lower distances, and high neural input even 1 year following ICU-discharge.

Discussion

Females infected by SARS-CoV-2 display significant impairments in functional recovery up to 1 year following ICU discharge. The effects of sex should be considered in post-COVID neurorehabilitation.

The role of the microcirculation and integrative cardiovascular physiology in the pathogenesis of ICU-acquired weakness

Skeletal muscle dysfunction after critical illness, defined as ICU-acquired weakness (ICU-AW), is a complex and multifactorial syndrome that contributes significantly to long-term morbidity and reduced quality of life for ICU survivors and caregivers. Historically, research in this field has focused on pathological changes within the muscle itself, without much consideration for their in vivo physiological environment. Skeletal muscle has the widest range of oxygen metabolism of any organ, and regulation of oxygen supply with tissue demand is a fundamental requirement for locomotion and muscle function. During exercise, this process is exquisitely controlled and coordinated by the cardiovascular, respiratory, and autonomic systems, and also within the skeletal muscle microcirculation and mitochondria as the terminal site of oxygen exchange and utilization. This review highlights the potential contribution of the microcirculation and integrative cardiovascular physiology to the pathogenesis of ICU-AW. An overview of skeletal muscle microvascular structure and function is provided, as well as our understanding of microvascular dysfunction during the acute phase of critical illness; whether microvascular dysfunction persists after ICU discharge is currently not known. Molecular mechanisms that regulate crosstalk between endothelial cells and myocytes are discussed, including the role of the microcirculation in skeletal muscle atrophy, oxidative stress, and satellite cell biology. The concept of integrated control of oxygen delivery and utilization during exercise is introduced, with evidence of physiological dysfunction throughout the oxygen delivery pathway - from mouth to mitochondria - causing reduced exercise capacity in patients with chronic disease (e.g., heart failure, COPD). We suggest that objective and perceived weakness after critical illness represents a physiological failure of oxygen supply-demand matching - both globally throughout the body and locally within skeletal muscle. Lastly, we highlight the value of standardized cardiopulmonary exercise testing protocols for evaluating fitness in ICU survivors, and the application of near-infrared spectroscopy for directly measuring skeletal muscle oxygenation, representing potential advancements in ICU-AW research and rehabilitation.

The epigenetic legacy of ICU feeding and its consequences

PURPOSE OF REVIEW

Many critically ill patients face physical, mental or neurocognitive impairments up to years later, the etiology remaining largely unexplained. Aberrant epigenetic changes have been linked to abnormal development and diseases resulting from adverse environmental exposures like major stress or inadequate nutrition. Theoretically, severe stress and artificial nutritional management of critical illness thus could induce epigenetic changes explaining long-term problems. We review supporting evidence.

RECENT FINDINGS

Epigenetic abnormalities are found in various critical illness types, affecting DNA-methylation, histone-modification and noncoding RNAs. They at least partly arise de novo after ICU-admission. Many affect genes with functions relevant for and several associate with long-term impairments. As such, de novo DNA-methylation changes in critically ill children statistically explained part of their disturbed long-term physical/neurocognitive development. These methylation changes were in part evoked by early-parenteral-nutrition (early-PN) and statistically explained harm by early-PN on long-term neurocognitive development. Finally, long-term epigenetic abnormalities beyond hospital-discharge have been identified, affecting pathways highly relevant for long-term outcomes.

SUMMARY

Epigenetic abnormalities induced by critical illness or its nutritional management provide a plausible molecular basis for their adverse effects on long-term outcomes. Identifying treatments to further attenuate these abnormalities opens perspectives to reduce the debilitating legacy of critical illness.

Patient mobilisation in the intensive care unit and evaluation of a multifaceted intervention including Facebook groups: A quasi-experimental study

AIMS

To describe prevalence and time to mobilisation in intensive care unit patients defined as a minimum sitting in an upright position in bed, and evaluate the impact of a multifaceted quality improvement campaign on likelihood of patients being mobilised.

RESEARCH METHODOLOGY/DESIGN

Quality improvement project using a quasi-experimental study design, comparing patient cohorts before (Before) and after (Intervention) a campaign including educational sessions, audit and feedback of intensive care unit quality indicators via closed Facebook-groups and e-mail and local opinion leaders. Secondary analysis of mobilisation data from adult intensive care patient stays extracted from electronical medical charts. Likelihood of being mobilised was analysed with Multivariate Cox-regression model and reported as Sub-hazard Ratio (SHR).

SETTING

Four intensive care units in a university hospital.

MAIN OUTCOME MEASURES

Prevalence and time to first documented mobilisation, defined as at least "sitting in bed" during the intensive care unit stay.

RESULTS

Overall, 929 patients were analysed, of whom 710 (76 %) were mobilised; 73 % (356/ 489) in Before vs 81 % (354/ 440) in Intervention (p = 0.007). Median time to mobilisation was 69.9 (IQR: 30.0, 149.8) hours; 71.7 (33.9, 157.9) in Before and 66.0 (27.1, 140.3) in Intervention (p = 0.104). Higher SAPS II-scores were associated with lower likelihood (SHR 0.98, 95 % CI 0.97-0.99), whereas admissions due to gastroenterological failure (SHR 2.1, 95 % CI 1.4-3.0), neurological failure (SHR 1.5, 95 % CI 1.0-2.2) and other causes (intoxication, postoperative care, haematological-, and kidney failure) (SHR 1.7, 95 % CI 1.13-2.6) were associated with higher likelihood of mobilisation vs respiratory failure.

CONCLUSION

A quality improvement campaign including use of Facebook groups is feasible and may improve mobilisation in intensive care unit patients. Most patients were mobilised within 72 hours following intensive care unit admission, and SAPS II scores and causes for intensive care unit admission were both associated with likelihood of being mobilised.

Congenital heart disease-associated pulmonary dysplasia and its underlying mechanisms

Clinical observation indicates that exercise capacity, an important determinant of survival in patients with congenital heart disease (CHD), is most decreased in children with reduced pulmonary blood flow (RPF). However, the underlying mechanism remains unclear. Here, we obtained human RPF lung samples from children with tetralogy of Fallot as well as piglet and rat RPF lung samples from animals with pulmonary artery banding surgery. We observed impaired alveolarization and vascularization, the main characteristics of pulmonary dysplasia, in the lungs of RPF infants, piglets, and rats. RPF caused smaller lungs, cyanosis, and body weight loss in neonatal rats and reduced the number of alveolar type 2 cells. RNA sequencing demonstrated that RPF induced the downregulation of metabolism and migration, a key biological process of late alveolar development, and the upregulation of immune response, which was confirmed by flow cytometry and cytokine detection. In addition, the immunosuppressant cyclosporine A rescued pulmonary dysplasia and increased the expression of the Wnt signaling pathway, which is the driver of postnatal lung development. We concluded that RPF results in pulmonary dysplasia, which may account for the reduced exercise capacity of patients with CHD with RPF. The underlying mechanism is associated with immune response activation, and immunosuppressants have a therapeutic effect in CHD-associated pulmonary dysplasia.

Long-term comprehensive cardiopulmonary phenotyping of COVID-19

Background

Persistent symptoms after initial COVID-19 infection are common and are frequently referred to by the umbrella terms “post-COVID syndrome” and “long COVID”. The sheer number of affected patients pose an increasing challenge to healthcare systems worldwide. To date, our understanding of the pathophysiology of the post-COVID syndrome remains poor and the extent to which persistent cardiopulmonary abnormalities contribute to the symptom complex is unclear. We sought to determine the presence and impact of cardiopulmonary sequelae after COVID-19 in longitudinal assessment.

Methods

We report on 71 patients who underwent comprehensive, longitudinal testing in regular intervals for up to 12 months after their initial COVID-19 diagnosis. Testing included pulmonary function testing, cardiopulmonary exercise testing, dedicated left and right heart echocardiography, lung ultrasonography, and cardiac MRI.

Results

Our results demonstrate that subjective quality of life after COVID-19 (EQ-5D visual acuity scale, VAS, 67.4 for patients treated as outpatient, 79.2 for patients admitted to the general floor, 71.8 for patients treated in an ICU) is not related to the severity of the initial infection. Maximal exercise capacity is also reduced (VO₂max 79% predicted, SD ± 19%); however, this is driven in large parts by patients who had initially required ICU-level of care. The degree of objective reduction in exertion did not correlate with quality of life scores. Pulmonary function testing revealed mild and persistent reduction in D_LCO over the first 12 months without significant restrictive or obstructive lung disease. Left and right heart function was intact with good RV function and intact RV/PA coupling, imaging findings suggestive of myocarditis were uncommon (7% of patients).

Conclusion

A reduction in exercise capacity after COVID-19 is common, but is most prominent in patients previously treated in the ICU and more likely related to deconditioning or fatigue than to cardiopulmonary impairment. Subjective quality of life scores are independent of the severity of initial infection and do not correlate with objective measures of cardiopulmonary function. In our cohort, persistent cardiopulmonary impairment after COVID-19 was uncommon. The post-COVID syndrome is unlikely to be the result of cardiopulmonary sequalae and may reflect a post-ICU syndrome in some.

Trial registration Registered on clinicaltrials.gov (NCT04442789), Date: June 23, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02173-9.

Self-reported limitations in physical function are common 6 months after out-of-hospital cardiac arrest

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Limitations in physical function are common in cardiac arrest survivors.

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Age and gender are associated with limitations in physical function.

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Cognitive impairment is a predictive variable for physical limitations.

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Anxiety and depression symptoms are associated with physical limitations.

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Physical function should be addressed at follow-up after cardiac arrest.

Title

Self-reported limitations in physical function are common 6 months after out-of-hospital cardiac arrest.

Background

Out-of-hospital cardiac arrest (OHCA) survivors generally report good health-related quality of life, but physical aspects of health seem more affected than other domains. Limitations in physical function after surviving OHCA have received little attention.

Aims

To describe physical function 6 months after OHCA and compare it with a group of ST elevation myocardial infarction (STEMI) controls, matched for country, age, sex and time of the cardiac event. A second aim was to explore variables potentially associated with self-reported limitations in physical function in OHCA survivors.

Methods

A cross-sectional sub-study of the Targeted Temperature Management at 33 °C versus 36 °C (TTM) trial with a follow-up 6 months post-event. Physical function was the main outcome assessed with the self-reported Physical Functioning-10 items scale (PF-10). PF-10 is presented as T-scores (0–100), where 50 represents the norm mean. Scores <47 at a group level, or <45 at an individual level indicate limitations in physical function.

Results

287 OHCA survivors and 119 STEMI controls participated. Self-reported physical function by PF-10 was significantly lower for OHCA survivors compared to STEMI controls (mean 46.0, SD 11.2 vs. 48.8, SD 9.0, p = 0.025). 38% of OHCA survivors compared to 26% of STEMI controls reported limitations in physical function at an individual level (p = 0.022). The most predictive variables for self-reported limitations in physical function in OHCA survivors were older age, female sex, cognitive impairment, and symptoms of anxiety and depression after 6 months.

Conclusion

Self-reported limitations in physical function are more common in OHCA survivors compared to STEMI controls.

Trial registration

ClinicalTrials.gov Identifier: NCT01946932.

Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study

Background

ICU survivors suffer from impaired physical function and reduced exercise capacity, yet the underlying mechanisms are poorly understood. The goal of this exploratory pilot study was to investigate potential mechanisms of exercise limitation using cardiopulmonary exercise testing (CPET) and 6-min walk testing (6MWT).

Methods

We enrolled adults aged 18 years or older who were treated for respiratory failure or shock in medical, surgical, or trauma ICUs at Vanderbilt University Medical Center (Nashville, TN, United States). We excluded patients with pre-existing cardiac dysfunction, a contraindication to CPET, or the need for supplemental oxygen at rest. We performed CPET and 6MWT 6 months after ICU discharge. We measured standard CPET parameters in addition to two measures of oxygen utilization during exercise (VO₂-work rate slope and VO₂ recovery half-time).

Results

We recruited 14 participants. Low exercise capacity (i.e., VO_2Peak < 80% predicted) was present in 11 out of 14 (79%) with a median VO_2Peak of 12.6 ml/kg/min [9.6–15.1] and 6MWT distance of 294 m [240–433]. In addition to low VO_2Peak, CPET findings in survivors included low oxygen uptake efficiency slope, low oxygen pulse, elevated chronotropic index, low VO₂-work rate slope, and prolonged VO₂ recovery half-time, indicating impaired oxygen utilization with a hyperdynamic heart rate and ventilatory response, a pattern seen in non-critically ill patients with mitochondrial myopathies. Worse VO₂-work rate slope and VO₂ recovery half-time were strongly correlated with worse VO_2Peak and 6MWT distance, suggesting that exercise capacity was potentially limited by impaired muscle oxygen utilization.

Conclusions

These exploratory data suggest ICU survivors may suffer from impaired muscular oxygen metabolism due to mitochondrial dysfunction that impairs exercise capacity long-term. These findings should be further characterized in future studies that include direct assessments of muscle mitochondrial function in ICU survivors.

A Global Survey on Diagnostic, Therapeutic and Preventive Strategies in Intensive Care Unit-Acquired Weakness

Background and Objectives: Intensive care unit-acquired weakness (ICU-AW) is one of the most frequent neuromuscular complications in critically ill patients. We conducted a global survey to evaluate the current practices of diagnostics, treatment and prevention in patients with ICU-AW. Materials and Methods: A pre-survey was created with international experts. After revision, the final survey was endorsed by the European Society of Intensive Care Medicine (ESICM) using the online platform SurveyMonkey®. In 27 items, we addressed strategies of diagnostics, therapy and prevention. An invitation link was sent by email to all ESICM members. Furthermore, the survey was available on the ESICM homepage. Results: A total of 154 healthcare professionals from 39 countries participated in the survey. An ICU-AW screening protocol was used by 20% (28/140) of participants. Forty-four percent (62/141) of all participants reported performing routine screening for ICU-AW, using clinical examination as the method of choice (124/141, 87.9%). Almost 63% (84/134) of the participants reported using current treatment strategies for patients with ICU-AW. The use of treatment and prevention strategies differed between intensivists and non-intensivists regarding the reduction in sedatives (80.0% vs. 52.6%, p = 0.002), neuromuscular blocking agents (76.4% vs. 50%, p = 0.004), corticosteroids (69.1% vs. 37.2%, p < 0.001) and glycemic control regimes (50.9% vs. 23.1%, p = 0.002). Mobilization and physical activity are the most frequently reported treatment strategies for ICU-AW (111/134, 82.9%). The availability of physiotherapists (92/134, 68.7%) and the lack of knowledge about ICU-AW within the medical team (83/134, 61.9%) were the main obstacles to the implementation of the strategies. The necessity to develop guidelines for the screening, diagnosing, treatment and prevention of ICU-AW was recognized by 95% (127/133) of participants. Conclusions: A great heterogeneity regarding diagnostics, treatment and prevention of ICU-AW was reported internationally. Comprehensive guidelines with evidence-based recommendations for ICU-AW management are needed.

Chronic critical illness and post-intensive care syndrome: from pathophysiology to clinical challenges

Background

Post‐intensive care syndrome (PICS) encompasses physical, cognition, and mental impairments persisting after intensive care unit (ICU) discharge. Ultimately it significantly impacts the long‐term prognosis, both in functional outcomes and survival. Thus, survivors often develop permanent disabilities, consume a lot of healthcare resources, and may experience prolonged suffering. This review aims to present the multiple facets of the PICS, decipher its underlying mechanisms, and highlight future research directions.

Main text

This review abridges the translational data underlying the multiple facets of chronic critical illness (CCI) and PICS. We focus first on ICU-acquired weakness, a syndrome characterized by impaired contractility, muscle wasting, and persisting muscle atrophy during the recovery phase, which involves anabolic resistance, impaired capacity of regeneration, mitochondrial dysfunction, and abnormalities in calcium homeostasis. Second, we discuss the clinical relevance of post-ICU cognitive impairment and neuropsychological disability, its association with delirium during the ICU stay, and the putative role of low-grade long-lasting inflammation. Third, we describe the profound and persistent qualitative and quantitative alteration of the innate and adaptive response. Fourth, we discuss the biological mechanisms of the progression from acute to chronic kidney injury, opening the field for renoprotective strategies. Fifth, we report long-lasting pulmonary consequences of ARDS and prolonged mechanical ventilation. Finally, we discuss several specificities in children, including the influence of the child’s pre-ICU condition, development, and maturation.

Conclusions

Recent understandings of the biological substratum of the PICS’ distinct features highlight the need to rethink our patient trajectories in the long term. A better knowledge of this syndrome and precipitating factors is necessary to develop protocols and strategies to alleviate the CCI and PICS and ultimately improve patient recovery.