Can proportional ventilation modes facilitate exercise in critically ill patients? A physiological cross-over study : Pressure support versus proportional ventilation during lower limb exercise in ventilated critically ill patients

Breathlessness assessment, management and impact in the intensive care unit: a rapid review and narrative synthesis

BACKGROUND

Adults in the intensive care unit (ICU) commonly experience distressing symptoms and other concerns such as pain, delirium, and breathlessness. Breathlessness management is not supported by any ICU guidelines, unlike other symptoms.

AIM

To review the literature relating to (i) prevalence, intensity, assessment, and management of breathlessness in critically ill adults in the ICU receiving invasive and non-invasive mechanical ventilation (NIV) and high-flow oxygen therapy, (HFOT), (ii) the impact of breathlessness on ICU patients with regard to engagement with rehabilitation.

METHODS

A rapid review and narrative synthesis using the Cochrane Methods Group Recommendations was conducted and reported in accordance with PRISMA. All study designs investigating breathlessness in adult ICU patients receiving either invasive mechanical ventilation (IMV), NIV or HFOT were eligible. PubMed, MEDLINE, The Cochrane Library and CINAHL databased were searched from June 2013 to June 2023. Studies were quality appraised.

RESULTS

19 studies representing 2822 ICU patients were included (participants mean age 48 years to 71 years; proportion of males 43-100%). The weighted mean prevalence of breathlessness in ICU patients receiving IMV was 49% (range 34-66%). The proportion of patients receiving NIV self-reporting moderate to severe dyspnoea was 55% prior to initiation. Breathlessness assessment tools included visual analogue scale, (VAS), numerical rating scale, (NRS) and modified BORG scale, (mBORG). In patients receiving NIV the highest reported median (interquartile range [IQR]) VAS, NRS and mBORG scores were 6.2cm (0-10 cm), 5 (2-7) and 6 (2.3-7) respectively (moderate to severe breathlessness). In patients receiving either NIV or HFOT the highest reported median (IQR) VAS, NRS and mBORG scores were 3 cm (0-6 cm), 8 (5-10) and 4 (3-5) respectively.

CONCLUSION

Breathlessness in adults receiving IMV, NIV or HFOT in the ICU is prevalent and clinically important with median intensity ratings indicating the presence of moderate to severe symptoms.

Dyspnoea in acutely ill mechanically ventilated adult patients: an ERS/ESICM statement

This statement outlines a review of the literature and current practice concerning the prevalence, clinical significance, diagnosis and management of dyspnoea in critically ill, mechanically ventilated adult patients. It covers the definition, pathophysiology, epidemiology, short- and middle-term impact, detection and quantification, and prevention and treatment of dyspnoea. It represents a collaboration of the European Respiratory Society and the European Society of Intensive Care Medicine. Dyspnoea ranks among the most distressing experiences that human beings can endure. Approximately 40% of patients undergoing invasive mechanical ventilation in the intensive care unit (ICU) report dyspnoea, with an average intensity of 45 mm on a visual analogue scale from 0 to 100 mm. Although it shares many similarities with pain, dyspnoea can be far worse than pain in that it summons a primal fear response. As such, it merits universal and specific consideration. Dyspnoea must be identified, prevented and relieved in every patient. In the ICU, mechanically ventilated patients are at high risk of experiencing breathing difficulties because of their physiological status and, in some instances, because of mechanical ventilation itself. At the same time, mechanically ventilated patients have barriers to signalling their distress. Addressing this major clinical challenge mandates teaching and training, and involves ICU caregivers and patients. This is even more important because, as opposed to pain which has become a universal healthcare concern, very little attention has been paid to the identification and management of respiratory suffering in mechanically ventilated ICU patients.

Dyspnoea in acutely ill mechanically ventilated adult patients: an ERS/ESICM statement

This statement outlines a review of the literature and current practice concerning the prevalence, clinical significance, diagnosis and management of dyspnoea in critically ill, mechanically ventilated adult patients. It covers the definition, pathophysiology, epidemiology, short- and middle-term impact, detection and quantification, and prevention and treatment of dyspnoea. It represents a collaboration of the European Respiratory Society (ERS) and the European Society of Intensive Care Medicine (ESICM). Dyspnoea ranks among the most distressing experiences that human beings can endure. Approximately 40% of patients undergoing invasive mechanical ventilation in the intensive care unit (ICU) report dyspnoea, with an average intensity of 45 mm on a visual analogue scale from 0 to 100 mm. Although it shares many similarities with pain, dyspnoea can be far worse than pain in that it summons a primal fear response. As such, it merits universal and specific consideration. Dyspnoea must be identified, prevented and relieved in every patient. In the ICU, mechanically ventilated patients are at high risk of experiencing breathing difficulties because of their physiological status and, in some instances, because of mechanical ventilation itself. At the same time, mechanically ventilated patients have barriers to signalling their distress. Addressing this major clinical challenge mandates teaching and training, and involves ICU caregivers and patients. This is even more important because, as opposed to pain which has become a universal healthcare concern, very little attention has been paid to the identification and management of respiratory suffering in mechanically ventilated ICU patients.

Neurally Adjusted Ventilatory Assist in Acute Respiratory Failure-A Narrative Review

Maintaining spontaneous breathing has both potentially beneficial and deleterious consequences in patients with acute respiratory failure, depending on the balance that can be obtained between the protecting and damaging effects on the lungs and the diaphragm. Neurally adjusted ventilatory assist (NAVA) is an assist mode, which supplies the respiratory system with a pressure proportional to the integral of the electrical activity of the diaphragm. This proportional mode of ventilation has the theoretical potential to deliver lung- and respiratory-muscle-protective ventilation by preserving the physiologic defense mechanisms against both lung overdistention and ventilator overassistance, as well as reducing the incidence of diaphragm disuse atrophy while maintaining patient–ventilator synchrony. This narrative review presents an overview of NAVA technology, its basic principles, the different methods to set the assist level and the findings of experimental and clinical studies which focused on lung and diaphragm protection, machine–patient interaction and preservation of breathing pattern variability. A summary of the findings of the available clinical trials which investigate the use of NAVA in acute respiratory failure will also be presented and discussed.

Feasibility of critical care ergometry: Exercise data of patients on mechanical ventilation analyzed as nine-panel plots

Nine-panel plots are standard displays of cardiopulmonary exercise data, used in cardiac and pulmonary medicine to investigate the nature of exercise limitation. We explored whether this approach could be used to analyze the data of critically ill patients on mechanical ventilation, capable of exercising actively. Patients followed an incremental exercise protocol using a bedside cycle ergometer. Respiratory gases were analyzed using indirect calorimetry, and blood gases were sampled from arterial catheters. Data of seven patients were combined into nine-panel plots. Systematic analysis clarified the nature of exercise limitation in six cases. Resting metabolic rate was increased in all patients, with a median oxygen uptake ( V˙O2 ) of 5.52 (IQR 4.29-6.31) ml/kg/min. Unloaded cycling increased the V˙O2 by 19.8% to 6.61 (IQR 5.99-7.08) ml/kg/min. Adding load to the ergometer increased the V˙O2 by another 20.0% to reach V˙O2peak at a median of 7.14 (IQR 6.67-10.75) ml/kg/min, corresponding to a median extrinsic workload of 7 W. This was accompanied by increased CO₂ production, respiratory minute volume, heart rate, and oxygen pulse. Three patients increased their V˙O2 to >40% of predicted V˙O2max , two patients passed the anaerobic threshold. Dead space ventilation was 44%, decreasing to 42% and accompanied by lower ventilatory equivalents during exercise. Exercise produced no net change in alveolo-arterial PO₂ difference. We concluded that diagnostic ergometry in mechanically ventilated patients was feasible. Analysis of the data as nine-panel plots provided insight into individual limitations to exercise.

Respiratory Support Adjustments and Monitoring of Mechanically Ventilated Patients Performing Early Mobilization: A Scoping Review

This scoping review is aimed to summarize current knowledge on respiratory support adjustments and monitoring of metabolic and respiratory variables in mechanically ventilated adult patients performing early mobilization.

DATA SOURCES

Eight electronic databases were searched from inception to February 2021, using a predefined search strategy.

STUDY SELECTION

Two blinded reviewers performed document selection by title, abstract, and full text according to the following criteria: mechanically ventilated adult patients performing any mobilization intervention, respiratory support adjustments, and/or monitoring of metabolic/respiratory real-time variables.

DATA EXTRACTION

Four physiotherapists extracted relevant information using a prespecified template.

DATA SYNTHESIS

From 1,208 references screened, 35 documents were selected for analysis, where 20 (57%) were published between 2016 and 2020. Respiratory support settings (ventilatory modes or respiratory variables) were reported in 21 documents (60%). Reported modes were assisted (n = 11) and assist-control (n = 9). Adjustment of variables and modes were identified in only seven documents (20%). The most frequent respiratory variable was the Fio2, and only four studies modified the level of ventilatory support. Mechanical ventilator brand/model used was not specified in 26 documents (74%). Monitoring of respiratory, metabolic, and both variables were reported in 22 documents (63%), four documents (11%) and 10 documents (29%), respectively. These variables were reported to assess the physiologic response (n = 21) or safety (n = 13). Monitored variables were mostly respiratory rate (n = 26), pulse oximetry (n = 22), and oxygen consumption (n = 9). Remarkably, no study assessed the work of breathing or effort during mobilization.

CONCLUSIONS

Little information on respiratory support adjustments during mobilization of mechanically ventilated patients was identified. Monitoring of metabolic and respiratory variables is also scant. More studies on the effects of adjustments of the level/mode of ventilatory support on exercise performance and respiratory muscle activity monitoring for safe and efficient implementation of early mobilization in mechanically ventilated patients are needed.

Settings and monitoring of mechanical ventilation during physical therapy in adult critically ill patients: protocol for a scoping review

INTRODUCTION

Early mobilisation has been extensively advocated to improve functional outcomes in critically ill patients, even though consistent evidence of its benefits has remained elusive. These conflicting results could be explained by a lack of knowledge on the optimal dosage of physical therapy and a mismatch between ventilatory support and exercise-induced patient ventilatory demand. Modern mechanical ventilators provide real-time monitoring of respiratory/metabolic variables and ventilatory setting that could be used for physical therapy dosage or ventilatory support titration, allowing individualised interventions in these patients. The aim of this review is to comprehensively map and summarise current knowledge on adjustments of respiratory support and respiratory or metabolic monitoring during physical therapy in adult critically ill mechanically ventilated patients.

METHODS AND ANALYSIS

This is a scoping review protocol based on the methodology of the Joanna-Briggs-Institute. The search strategy will be conducted from inception to 30 June 2019 as a cut-off date in PubMed, CINAHL, Rehabilitation & Sport Medicine, Scielo Citation Index, Epistemónikos, Clinical Trials, PEDro and Cochrane Library, performed by a biomedical librarian and two critical care physiotherapists. All types of articles will be selected, including conference abstracts, clinical practice guidelines and expert recommendations. Bibliometric variables, patient characteristics, physical therapy interventions, ventilator settings and respiratory or metabolic monitoring will be extracted. The identified literature will be analysed by four critical care physiotherapists and reviewed by a senior critical care physician.

ETHICS AND DISSEMINATION

Ethical approval is not required. The knowledge-translation of the results will be carried out based on the End-of-Grant strategies: diffusion, dissemination and application. The results will be published in a peer-review journal, presentations will be disseminated in relevant congresses, and recommendations based on the results will be developed through training for mechanical ventilation and physical therapy stakeholders.

Proportional modes versus pressure support ventilation: a systematic review and meta-analysis

Background

Proportional modes (proportional assist ventilation, PAV, and neurally adjusted ventilatory assist, NAVA) could improve patient–ventilator interaction and consequently may be efficient as a weaning mode. The purpose of this systematic review is to examine whether proportional modes improved patient–ventilator interaction and whether they had an impact on the weaning success and length of mechanical ventilation, in comparison with PSV.

Methods

We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials from inception through May 13, 2018. We included both parallel-group and crossover randomized studies that examined the efficacy of proportional modes in comparison with PSV in mechanically ventilated adults. The primary outcomes were (1) asynchrony index (AI), (2) weaning failure, and (3) duration of mechanical ventilation.

Results

We included 15 studies (four evaluated PAV, ten evaluated NAVA, and one evaluated both modes). Although the use of proportional modes was not associated with a reduction in AI (WMD − 1.43; 95% CI − 3.11 to 0.25; p = 0.096; PAV—one study, and NAVA—seven studies), the use of proportional modes was associated with a reduction in patients with AI > 10% (RR 0.15; 95% CI 0.04–0.58; p = 0.006; PAV—two studies, and NAVA—five studies), compared with PSV. There was a significant heterogeneity among studies for AI, especially with NAVA. Compared with PSV, use of proportional modes was associated with a reduction in weaning failure (RR 0.44; 95% CI 0.26–0.75; p = 0.003; PAV—three studies) and duration of mechanical ventilation (WMD − 1.78 days; 95% CI − 3.24 to − 0.32; p = 0.017; PAV—three studies, and NAVA—two studies). Reduced duration of mechanical ventilation was found with PAV but not with NAVA.

Conclusion

The use of proportional modes was associated with a reduction in the incidence with AI > 10%, weaning failure and duration of mechanical ventilation, compared with PSV. However, reduced weaning failure and duration of mechanical ventilation were found with only PAV. Due to a significant heterogeneity among studies and an insufficient number of studies, further investigation seems warranted to better understand the impact of proportional modes.

Clinical trial registration PROSPERO registration number, CRD42017059791. Registered 20 March 2017

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0470-y) contains supplementary material, which is available to authorized users.

Non-Invasive Ventilation as an Adjunct to Exercise Training in Chronic Ventilatory Failure: A Narrative Review

BACKGROUND

Chronic ventilatory failure (CVF) may be associated with reduced exercise capacity. Long-term non-invasive ventilation (NIV) may reduce patients' symptoms, improve health-related quality of life and reduce mortality and hospitalisations. There is an increasing use of NIV during exercise training with the purpose to train patients at intensity levels higher than allowed by their pathophysiological conditions.

OBJECTIVE

This narrative review describes the possibility to train patients with CVF and NIV use as a tool to increase the benefits of exercise training.

METHODS

We searched papers published between 1985 and 2018 in (or with the summary in) English language in PubMed and Scopus databases using the keywords "chronic respiratory failure AND exercise," "non invasive ventilation AND exercise," "pulmonary rehabilitation" and "exercise training."

RESULTS

Exercise training is feasible and effective also in patients with CVF. Assisted ventilation can improve exercise tolerance in different clinical conditions. In patients under long-term home ventilatory support, NIV administered also during walking results in improved oxygenation, decreased dyspnoea and increased walking distance. Continuous positive airway pressure and different modalities of assisted ventilation have been delivered through different interfaces during exercise training programmes. Patients with CVF on long-term NIV may benefit from exercising with the same ventilators, interfaces and settings as used at home.

CONCLUSION

We need more randomised clinical trials to investigate the effects of NIV on exercise training in patients with CVF and define organisation and setting.

Recent evidence on early mobilization in critical-Ill patients

PURPOSE OF REVIEW

To examine the benefits of early mobilization and summarize the results of most recent clinical studies examining early mobilization in critically ill patients followed by a presentation of recent developments in the field.

RECENT FINDINGS

Early mobilization of ICU patients, defined as mobilization within 72 h of ICU admission, is still uncommon. In medical and surgical critically ill patients, mobilization is well tolerated even in intubated patients. In neurocritical care, evidence to support early mobilization is either lacking (aneurysmal subarachnoid hemorrhage), or the results are inconsistent (e.g. stroke). Successful implementation of early mobilization requires a cultural change; preferably based on an interprofessional approach with clearly defined responsibilities and including a mobilization scoring system. Although the evidence for the majority of the technical tools is still limited, the use of a bed cycle ergometer and a treadmill with strap system has been promising in smaller trials.

SUMMARY

Early mobilization is well tolerated and feasible, resulting in improved outcomes in surgical and medical ICU patients. Implementation of early mobilization can be challenging and may need a cultural change anchored in an interprofessional approach and integrated in a patient-centered bundle. Scoring systems should be integrated to define daily goals and used to verify patients' achievements or identify barriers immediately.

Evidence Supporting Clinical Use of Proportional Assist Ventilation: A Systematic Review and Meta-Analysis of Clinical Trials

BACKGROUND

While proportional assist ventilation (PAV), generates pressure in proportion to effort without a preselected target, proportional assist ventilation plus (PAV+) measures compliance and resistance, calculates work of breathing, and adjusts support to a preset assistance level.

OBJECTIVE

To summarize randomized controlled trials (RCTs) comparing invasive or noninvasive PAV or PAV+ in critically ill patients. Data Sources: We searched multiple databases to April 2017 without language restrictions and conference proceedings from 5 meetings to identify randomized parallel-group and crossover RCTs that compared invasive or noninvasive PAV or PAV+ to another mode in critically ill adults or children and reported at least 1 clinically important outcome.

RESULTS

We identified 14 RCTs (11 parallel group and 3 crossover) assessing PAV (n = 7) and PAV+ (n = 7) involving 931 adult patients. We found no effect of noninvasive PAV (vs noninvasive pressure support [PS]) on intubation (risk ratio 0.92 [0.59 to 1.43], I² = 0%) or invasive PAV (vs invasive PS) on percentage rapid eye movement sleep (mean difference [MD] -2.93% [-14.20 to ±8.34], I² = 43%). Compared to invasive PS, invasive PAV+ showed a nonsignificant increase in weaning time (MD +0.54 [-0.67 to +1.75] hours, I² = 0%), but no effect on hospital mortality, reintubation, or tracheostomy.

CONCLUSIONS

Current evidence does not support the use of invasive or noninvasive PAV or invasive PAV+ in critically ill adults. Amid low to moderate heterogeneity, we identified 3 promising areas for future research including assessing the role of noninvasive PAV as an initial support strategy in patients with acute respiratory failure, invasive PAV on sleep quality during invasive ventilation, and possibly invasive PAV+ for weaning.