Coexistence and Impact of Limb Muscle and Diaphragm Weakness at Time of Liberation from Mechanical Ventilation in Medical Intensive Care Unit Patients

Effectiveness of physical exercise and neuromuscular electrical stimulation interventions for preventing and treating intensive care unit-acquired weakness: A systematic review of randomized controlled trials

OBJECTIVE

Intensive care unit-acquired weakness is a frequent problem that develops as a secondary disorder while patients are suffering from life-threatening conditions. This study aimed to evaluate the effectiveness of physical exercise or neuromuscular electrical stimulation interventions on (i) preventing loss of muscle mass and weakness in critically ill patients admitted to intensive care units; (ii) recovering patients discharged from the intensive care unit with acquired weakness.

METHODS

A systematic review of randomized controlled trials was carried out, with studies identified in PubMed, Scopus, and Web of Science. The studies included assessed muscle mass and muscle strength, and performed a time × group analysis of effects. The risk of bias assessment was performed using the Revised Cochrane risk-of-bias tool for randomized trials.

RESULTS

Six trials with low risk of bias examined muscle mass, muscle strength, and functionality in 182 adult patients. In critically ill patients admitted to intensive care units, both neuromuscular electrical stimulation and bed/chair cycling for five to ten days prevented significant muscle loss. neuromuscular electrical stimulation in lower and upper limbs resulted in a significant reduction in the length of the hospitalization. In addition, cycle ergometer increased muscle strength and functionality. In patients discharged from the intensive care unit with acquired weakness, both neuromuscular electrical stimulation and physical exercise interventions increased muscle strength, but only physical exercise increased functionality.

CONCLUSIONS

Physical exercise and neuromuscular electrical stimulation interventions prevent excessive muscle mass loss in critically ill patients admitted to the intensive care unit and increase muscle strength in patients discharged from the intensive care unit with acquired weakness. Physical exercise seems more adequate for improving functionality.

Early passive orthostatic training prevents diaphragm atrophy and dysfunction in intensive care unit patients on mechanical ventilation: A retrospective case‒control study

BACKGROUND

Intensive care unit (ICU) patients on mechanical ventilation (MV), who are always bedridden, easily develop diaphragm atrophy and dysfunction. However, few studies have assessed diaphragmatic thickness and functional changes after early passive orthostatic training.

OBJECTIVES

This is the first study to investigate the efficacy of early passive orthostatic training in preventing diaphragm atrophy and dysfunction in ICU patients on MV.

METHODS

In this randomized retrospective case‒control study, 81 ICU patients on MV for 8 days or longer were enrolled. Forty-four patients received early passive orthostatic training initiated within 72 h of MV initiation (training group), and 37 patients did not receive training (no-training group). The protocol was performed for seven days, once a day for 30 min. The primary outcomes were diaphragmatic thickness and diaphragm contractile fraction (TFdi). The ventilatory parameters were secondary outcomes.

RESULTS

This study included 81 (45 male) ICU patients on MV [(mean ± SD) age = (60.63 ± 7.88) years]. The training group had a larger diaphragmatic thickness at end-expiration (Tdi_,ee) and a smaller magnitude of decrease in Tdi_,ee and TFdi (p = 0.001, 0.029, and <0.001, respectively) than the no-training group after 7 days of training. The mean arterial pressure, fraction of inspired oxygen, and white blood cell levels were decreased in the training group compared with the no-training group (p = 0.003, 0.001, and 0.026, respectively), but lactic acid levels decreased slightly in the training group with no significant difference (p = 0.708).

CONCLUSIONS

Early passive orthostatic training is suitable to ameliorate diaphragm atrophy and dysfunction in ICU patients on MV.

Inspiratory muscle strength and function in mechanically ventilated COVID-19 survivors 3 and 6 months after intensive care unit discharge

Background

Knowledge regarding the long-term impact of invasive mechanical ventilation on the inspiratory muscles and functional outcomes in COVID-19 survivors is limited.

Methods

In this single-centre prospective cohort study, we evaluated invasively ventilated patients with COVID-19 pneumonia 3 and 6 months post-intensive care unit (ICU) discharge. Outcomes included: maximal inspiratory pressure (MIP), ultrasound parameters for diaphragm function, 6-min walk distance (6MWD), dyspnoea and quality of life. We evaluated associations between MIP and duration of mechanical ventilation with follow-up outcomes.

Results

50 COVID-19 survivors discharged from ICU between 15 October 2020 and 1 April 2021 were enrolled. Overall, survivors showed a recovery trajectory over time. However, impaired MIP remained in 24 (48%) and 12 (24%) at 3 and 6 months, respectively. Diaphragm dysfunction was not observed. At 3 months, 23 (46%) had impaired functional capacity versus 10 (20%) at 6 months. Dyspnoea persisted in 44 (88%) patients at 3 months and 38 (76%) at 6 months. Quality of life was slightly decreased at 3 months with further improvements at 6 months. MIP was correlated to 6MWD, 6MWD % predicted, dyspnoea across follow-up, and quality of life at 3 months. The duration of invasive ventilation was correlated with 6MWD and 6MWD % predicted.

Conclusion

In invasively ventilated COVID-19 survivors, inspiratory muscle strength impairments persisted 6 months after ICU discharge, while maintaining normal diaphragm function. Decreased functional capacity, dyspnoea and slightly reduced health status were observed. Early screening of survivors is of utmost importance to identify those with impairments and at risk of delayed or incomplete recovery.

No association between thickening fraction of the diaphragm and extubation success in ventilated children

Introduction

In mechanically ventilated adults, thickening fraction of diaphragm (dTF) measured by ultrasound is used to predict extubation success. Whether dTF can also predict extubation success in children is unclear.

Aim

To investigate the association between dTF and extubation success in children. Second, to assess diaphragm thickness during ventilation and the correlation between dTF, diaphragm thickness (Tdi), age and body surface.

Method

Prospective observational cohort study in children aged 0-18 years old with expected invasive ventilation for >48 h. Ultrasound was performed on day 1 after intubation (baseline), day 4, day 7, day 10, at pre-extubation, and within 24 h after extubation. Primary outcome was the association between dTF pre-extubation and extubation success. Secondary outcome measures were Tdi end-inspiratory and Tdi end-expiratory and atrophy defined as <10% decrease of Tdi end-expiratory versus baseline at pre-extubation. Correlations were calculated with Spearman correlation coefficients. Inter-rater reliability was calculated with intraclass correlation (ICC).

Results

Fifty-three patients, with median age 3.0 months (IQR 0.1-66.0) and median duration of invasive ventilation of 114.0 h (IQR 55.5-193.5), were enrolled. Median dTF before extubation with Pressure Support 10 above 5 cmH₂O was 15.2% (IQR 9.7-19.3). Extubation failure occurred in six children, three of whom were re-intubated and three then received non-invasive ventilation. There was no significant association between dTF and extubation success; OR 0.33 (95% CI; 0.06-1.86). Diaphragmatic atrophy was observed in 17/53 cases, in three of extubation failure occurred. Children in the extubation failure group were younger: 2.0 months (IQR 0.81-183.0) vs. 3.0 months (IQR 0.10-48.0); p = 0.045. At baseline, pre-extubation and post-extubation there was no significant correlation between age and BSA on the one hand and dTF, Tdi- insp and Tdi-exp on the other hand. The ICC representing the level of inter-rater reliability between the two examiners performing the ultrasounds was 0.994 (95% CI 0.970-0.999). The ICC of the inter-rater reliability between the raters in 36 paired assessments was 0.983 (95% CI 0.974-0.990).

Conclusion

There was no significant association between thickening fraction of the diaphragm and extubation success in ventilated children.

Rbm20ΔRRM Mice, Expressing a Titin Isoform with Lower Stiffness, Are Protected from Mechanical Ventilation-Induced Diaphragm Weakness

Diaphragm weakness frequently develops in mechanically ventilated critically ill patients and is associated with increased morbidity, including ventilator weaning failure, mortality, and health care costs. The mechanisms underlying diaphragm weakness are incompletely understood but may include the elastic properties of titin, a giant protein whose layout in the muscle's sarcomeres makes it an ideal candidate to sense ventilation-induced diaphragm unloading, resulting in downstream signaling through titin-binding proteins. In the current study, we investigated whether modulating titin stiffness affects the development of diaphragm weakness during mechanical ventilation. To this end, we ventilated genetically engineered mice with reduced titin stiffness (Rbm20^ΔRRM), and robust (Ttn^ΔIAjxn) or severely (Ttn^Δ112-158) increased titin stiffness for 8 h, and assessed diaphragm contractility and protein expression of titin-binding proteins. Mechanical ventilation reduced the maximum active tension of the diaphragm in WT, Ttn^ΔIAjxn and Ttn^Δ112-158 mice. However, in Rbm20^ΔRRM mice maximum active tension was preserved after ventilation. Analyses of titin binding proteins suggest that muscle ankyrin repeat proteins (MARPs) 1 and 2 may play a role in the adaptation of the diaphragm to mechanical ventilation, and the preservation of diaphragm contractility in Rbm20^ΔRRM mice. Thus, Rbm20^ΔRRM mice, expressing titin isoforms with lower stiffness, are protected from mechanical ventilation-induced diaphragm weakness, suggesting that titin elasticity may modulate the diaphragm's response to unloading during mechanical ventilation.

Exploring the Influence of Dysphagia and Tracheostomy on Pneumonia in Patients with Stroke: A Retrospective Cohort Study

Background: Pneumonia is common in patients with tracheostomy and dysphagia. However, the influence of dysphagia and tracheostomy on pneumonia in patients with stroke remains unclear. The aim of this study was to explore the risk factors related to pneumonia, and the association between dysphagia, tracheostomy and pneumonia in patients with stroke was investigated. Methods: Patients with stroke who experienced tracheostomy and dysphagia were included and divided into two groups based on record of pneumonia at discharge. Clinical manifestations and physical examination were used to diagnose pneumonia, whereas clinical swallowing examination, and videofluoroscopy swallowing studies (VFSS) were used to evaluate swallowing function. Results: There were significant differences between the pneumonia group and the no pneumonia group in total tracheostomy time (6.3 ± 5.9 vs. 4.3 ± 1.7 months, p = 0.003), number of instances of ventilator support (0.41 ± 0.49 vs. 0.18 ± 0.38, p = 0.007), PAS score (5.2 ± 1.92 vs. 4.3 ± 1.79, p = 0.039), impaired or absent cough reflex (76.4 vs. 55.6%, p = 0.035), oropharyngeal phase dysfunction (60.6 vs. 40.8%, p = 0.047), length of hospital stay (36.0 ± 7.2 vs. 30.5 ± 11.7 days, p = 0.025) and direct medical costs (15,702.21 ± 14,244.61 vs. 10,923.99 ± 7250.14 United States dollar [USD], p = 0.042). Multivariate logistic regression showed that the total tracheostomy time (95% confidence interval [CI], 1.966−12.922, p = 0.001), impaired or absent cough reflex (95% CI, 0.084−0.695, p = 0.008), and oropharyngeal phase dysfunction (95% CI, 1.087−8.148, p = 0.034) were risk factors for pneumonia. Spearman’s correlation analysis demonstrated that PAS scores were significantly correlated with cough reflex dysfunction (r = 0.277, p = 0.03), oropharyngeal phase dysfunction (r = 0.318, p < 0.01) and total tracheostomy time (r = 0.178, p = 0.045). The oropharyngeal phase dysfunction was significantly correlated with cough reflex (r = 0.549, p < 0.001) and UES opening (r = 0.643, p < 0.01). Conclusions: Tracheostomy and dysphagia increased the risk of pneumonia in patients with stroke. Total tracheostomy time, duration of ventilator support, degree of penetration and aspiration, and oropharyngeal phase dysfunction are risk factors. Given this, we also found that there may be a correlation between tracheostomy and dysphagia.

The PROMIZING trial enrollment algorithm for early identification of patients ready for unassisted breathing

Background

Liberating patients from mechanical ventilation (MV) requires a systematic approach. In the context of a clinical trial, we developed a simple algorithm to identify patients who tolerate assisted ventilation but still require ongoing MV to be randomized. We report on the use of this algorithm to screen potential trial participants for enrollment and subsequent randomization in the Proportional Assist Ventilation for Minimizing the Duration of MV (PROMIZING) study.

Methods

The algorithm included five steps: enrollment criteria, pressure support ventilation (PSV) tolerance trial, weaning criteria, continuous positive airway pressure (CPAP) tolerance trial (0 cmH₂O during 2 min) and spontaneous breathing trial (SBT): on fraction of inspired oxygen (F_iO₂) 40% for 30–120 min. Patients who failed the weaning criteria, CPAP Zero trial, or SBT were randomized. We describe the characteristics of patients who were initially enrolled, but passed all steps in the algorithm and consequently were not randomized.

Results

Among the 374 enrolled patients, 93 (25%) patients passed all five steps. At time of enrollment, most patients were on PSV (87%) with a mean (± standard deviation) F_iO₂ of 34 (± 6) %, PSV of 8.7 (± 2.9) cmH₂O, and positive end-expiratory pressure of 6.1 (± 1.6) cmH₂O. Minute ventilation was 9.0 (± 3.1) L/min with a respiratory rate of 17.4 (± 4.4) breaths/min. Patients were liberated from MV with a median [interquartile range] delay between initial screening and extubation of 5 [1–49] hours. Only 7 (8%) patients required reintubation.

Conclusion

The trial algorithm permitted identification of 93 (25%) patients who were ready to extubate, while their clinicians predicted a duration of ventilation higher than 24 h.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04063-4.

YAP1 silencing attenuated lung injury/fibrosis but worsened diaphragmatic function by regulating oxidative stress and inflammation response in mice

Oxidative stress is a crucial mechanism in the pathophysiology of lung injury/fibrosis and diaphragmatic dysfunction. Yes-associated protein 1 (YAP1) is a key oxidative stress response regulator. However, how lung injury/fibrosis and the subsequent YAP1 silencing treatment affect diaphragmatic function remains largely uncharacterized. In this study, mice models of acute lipopolysaccharide (LPS) and paraquat exposure were used to establish acute lung injury and chronic pulmonary fibrosis. AT2 and C2C12 cells were co-cultured under LPS and paraquat challenge. YAP1 was interfered with shRNA given in vivo and verteporfin administration in vitro. Pulmonary histology, contractile properties, and cross-sectional areas (CSAs) of the diaphragm and gastrocnemius were evaluated. Histological and biochemical analyses were performed for targeted biomarker determination. We found that LPS and paraquat caused significant lung injury/fibrosis and significantly reduced the diaphragmatic-specific force and CSAs compared with the control. YAP1 silencing alleviated inflammatory cell infiltration or collagen deposition in the lungs yet worsened the already impaired diaphragmatic function by increasing inflammatory cytokines (IL-6 and TNF-α), mitochondrial reactive oxidative species (ROS) emission, protein degradation (Murf-1, atrogin-1, and calpain), and decreasing antioxidant capabilities (superoxide dismutase 2 and glutathione peroxidase). No significant improvements were observed in diaphragmatic function by transient YAP1 knockdown in the gastrocnemius. In vitro, LPS- or paraquat-caused cytotoxicity in AT2 cells was mostly alleviated by verteporfin in a concentration that was 20-fold higher than that in C2C12 cells (20 and 1 μg/mL, respectively). Finally, 0.5 μg/mL of verteporfin significantly ameliorated hydrogen peroxide-induced proteolytic activity and antioxidant enzyme suppression in C2C12 cells, whereas 2 μg/mL of verteporfin deteriorated the same. Collectively, lung injury/fibrosis adversely affects the diaphragm. YAP1 inhibition alleviates lung injury/fibrosis but worsens diaphragmatic function potentially by enhancing inflammatory cytokines and ROS-mediated protein degradation. This disparity might be attributed to differences in susceptibility to YAP1 inhibition between muscles and the lungs.

Update on the use of ultrasound in the diagnosis and monitoring of the critical patient

Hemodynamic and respiratory complications are the main causes of morbidity and mortality in in critical care units (CCU). Imaging techniques are a key tool in differential diagnosis and treatment. In the last decade, ultrasound has shown great potential for bedside diagnosis of respiratory disease, as well as for the hemodynamic assessment of critically ill patients. Ultrasound has proven to be a useful guide for identifying the type of shock, estimating cardiac output, guiding fluid therapy and vasoactive drugs, providing security in the performance of percutaneous techniques (thoracentesis, pericardiocentesis, evacuation of abscesses/hematomas), detecting dynamically in real time pulmonary atelectasis and its response to alveolar recruitment maneuvers, and predicting weaning failure from mechanical ventilation. Due to its dynamic nature, simple learning curve and absence of ionizing radiation, it has been incorporated as an essential tool in daily clinical practice in CCUs. The objective of this review is to offer a global vision of the role of ultrasound and its applications in the critically ill patient.

Does mechanical threshold inspiratory muscle training promote recovery and improve outcomes in patients who are ventilator-dependent in the intensive care unit? The IMPROVE randomised trial

BACKGROUND

In patients who are ventilator-dependent in the intensive care unit, inspiratory muscle training may improve inspiratory muscle strength and accelerate liberation from the ventilator, but optimal training parameters are yet to be established, and little is known about the impact of inspiratory muscle training on quality of life or dyspnoea. Thus, we sought to ascertain whether inspiratory muscle training, commenced while ventilator-dependent, would improve outcomes for patients invasively ventilated for 7 days or longer.

METHODS

In this randomised trial with assessor blinding and intention-to-treat analysis, 70 participants (mechanically ventilated ≥7 days) were randomised to receive once-daily supervised high-intensity inspiratory muscle training with a mechanical threshold device in addition to usual care or to receive usual care (control). Primary outcomes were inspiratory muscle strength (maximum inspiratory pressure % predicted) and endurance (fatigue resistance index) at ventilator liberation and 1 week later. Secondary outcomes included quality of life (SF-36v2, EQ-5D), dyspnoea, physical function, duration of ventilation, and in-hospital mortality.

RESULTS

Thirty-three participants were randomly allocated to the training group, and 37 to the control group. There were no statistically significant differences in strength (maximum inspiratory pressure) (95% confidence interval [CI]: -7.4 to 14.0) or endurance (fatigue resistance index) (95% CI: -0.003 to 0.436). Quality of life improved significantly more in the training group than in the control group (EQ-5D: 17.2; 95% CI: 1.3-33.0) (SF-36-PCS: 6.97; 95% CI: 1.96-12.00). Only the training group demonstrated significant reductions in dyspnoea (-1.5 at rest, -1.9 during exercise). There were no between-group differences in duration of ventilation or other measures. In-hospital mortality was higher in the control group than in the training group (9 vs 4, 24% vs 12%, p = 0.23).

CONCLUSIONS

In patients who are ventilator-dependent, mechanical threshold loading inspiratory muscle training improves quality of life and dyspnoea, even in the absence of strength improvements or acceleration of ventilator liberation.

Relationships between double cycling and inspiratory effort with diaphragm thickness during the early phase of mechanical ventilation: A prospective observational study

Background

Increased and decreased diaphragm thickness during mechanical ventilation is associated with poor outcomes. Some types of patient-ventilator asynchrony theoretically cause myotrauma of the diaphragm. However, the effects of double cycling on structural changes in the diaphragm have not been previously evaluated. Hence, this study aimed to investigate the relationship between double cycling during the early phase of mechanical ventilation and changes in diaphragm thickness, and the involvement of inspiratory effort in the occurrence of double cycling.

Methods

We evaluated adult patients receiving invasive mechanical ventilation for more than 48 h. The end-expiratory diaphragm thickness (Tdi_ee) was assessed via ultrasonography on days 1, 2, 3, 5 and 7 after the initiation of mechanical ventilation. Then, the maximum rate of change from day 1 (ΔTdi_ee%) was evaluated. Concurrently, we recorded esophageal pressure and airway pressure on days 1, 2 and 3 for 1 h during spontaneous breathing. Then, the waveforms were retrospectively analyzed to calculate the incidence of double cycling (double cycling index) and inspiratory esophageal pressure swing (ΔP_es). Finally, the correlation between double cycling index as well as ΔP_es and ΔTdi_ee% was investigated using linear regression models.

Results

In total, 19 patients with a median age of 69 (interquartile range: 65–78) years were enrolled in this study, and all received pressure assist-control ventilation. The Tdi_ee increased by more than 10% from baseline in nine patients, decreased by more than 10% in nine and remained unchanged in one. The double cycling indexes on days 1, 2 and 3 were 2.2%, 1.3% and 4.5%, respectively. There was a linear correlation between the double cycling index on day 3 and ΔTdi_ee% (R² = 0.446, p = 0.002). The double cycling index was correlated with the ΔP_es on days 2 (R² = 0.319, p = 0.004) and 3 (R² = 0.635, p < 0.001).

Conclusions

Double cycling on the third day of mechanical ventilation was associated with strong inspiratory efforts and, possibly, changes in diaphragm thickness.

Occurrence and Effects on Weaning From Mechanical Ventilation of Intensive Care Unit Acquired and Diaphragm Weakness: A Pilot Study

Purpose

Limb intensive care unit (ICU)-acquired weakness (ICUAW) and ICU acquired diaphragm weakness (DW) occur frequently in mechanically ventilated (MV) patients; their coexistence in cooperative and uncooperative patients is unknown. This study was designed to (1) describe the co-occurrence of the two conditions (2) evaluate the impact of ICUAW and DW on the ventilator-free days (VFDs) at 28 days and weaning success, and (3) assess the correlation between maximal inspiratory pressure (MIP) and thickening fraction (TFdi) in patients with DW.

Methods

This prospective pilot study was conducted in a single-center on 73 critically ill MV patients. Muscle weakness was defined as a Medical Research Council score &lt; 48 in cooperative patients or a bilateral mean simplified peroneal nerve test &lt; 5.26 mV in uncooperative patients. Diaphragm dysfunction was defined as MIP &lt; 30 cm H2O or as a TFdi &lt; 29%. Weaning success was defined according to weaning according to a new definition (WIND).

Results

Fifty-seven patients (78%) had ICUAW and 59 (81%) had DW. The coexistence of the two conditions occurred in 48 patients (65%), without association (χ2 = 1.06, p = 0.304). In the adjusted analysis, ICUAW was independently related to VFDs at 28-days (estimate difference 6 days, p = 0.016), and WIND (OR of 3.62 for having WIND different than short weaning), whereas DW was not. The linear mixed model showed a significant but weak correlation between MIP and TFdi (p &lt; 0.001).

Conclusion

This pilot study is the first to explore the coexistence of ICUAW and DW in both cooperative and uncooperative patients; a lack of association was found between DW and ICUAW when considering both cooperative and uncooperative patients. We found a strong correlation between ICUAW but not DW with the VFDs at 28 days and weaning success. A future larger study is warranted in order to confirm our results, and should also investigate the use of transdiaphragmatic twitch pressure measurement during bilateral anterior magnetic phrenic nerve stimulation for the diagnosis of DW.

Body composition and risk factors associated with sarcopenia in post-COVID patients after moderate or severe COVID-19 infections

Background

Post-COVID-19 syndrome is characterized by diverse symptoms and abnormalities that persist beyond 12 weeks from the onset of acute COVID-19. Severity disease has been associated with more musculoskeletal alterations such as muscle weakness, dyspnea, and distance walking. The aim was to evaluate the impact of invasive mechanical ventilation (IMV) on body composition and investigate risk factors associated with sarcopenia in post-COVID-19 patients three months after moderate or severe COVID-19 infections.

Methods

Cross-sectional study. 530 patients with PCR-confirmed diagnoses of moderate to severe COVID-19, > 18 years old, oxygen saturation ≤ 93%, PaO₂/FiO₂ ratio < 300, who required hospitalization and were discharged were included. We excluded those who died before the follow-up visit, declined to participate, or could not be contacted.

Results

The mean age was 53.79 ± 12.90 years. IMV subjects had lower phase angle and handgrip strength and higher impedance index, frequency of low muscle mass, and low muscle strength than those without IMV. The risk factors of sarcopenia were > 60 years of age, diabetes, obesity, IMV, and prolonged hospital stay. The multivariate model showed that age > 60 years (OR: 4.91, 95% CI: 2.26–10.63), obesity (OR: 3.73, 95% CI: 1.21–11.54), and interaction between prolonged length of hospital stay and IMV (OR: 2.92; 95% CI: 1.21–7.02) were related to a higher risk of sarcopenia.

Conclusion

Obesity and the interaction between prolonged length of hospital stay and IMV are associated with a higher risk of sarcopenia at 3 months after severe or moderate COVID-19 infection.

The weaning from mechanical ventilation: a comprehensive ultrasound approach

PURPOSE OF REVIEW

Due to heart, lung and diaphragm interactions during weaning from mechanical ventilation, an ultrasound integrated approach may be useful in the detection of dysfunctions potentially leading to weaning failure. In this review, we will summarize the most recent advances concerning the ultrasound applications relevant to the weaning from mechanical ventilation.

RECENT FINDINGS

The role of ultrasonographic examination of heart, lung and diaphragm has been deeply investigated over the years. Most recent findings concern the ability of lung ultrasound in detecting weaning induced pulmonary edema during spontaneous breathing trial. Furthermore, in patients at high risk of cardiac impairments, global and anterolateral lung ultrasound scores have been correlated with weaning and extubation failure, whereas echocardiographic indexes were not. For diaphragmatic ultrasound evaluation, new indexes have been proposed for the evaluation of diaphragm performance during weaning, but further studies are needed to validate these results.

SUMMARY

The present review summarizes the potential role of ultrasonography in the weaning process. A multimodal integrated approach allows the clinician to comprehend the pathophysiological processes of weaning failure.

Effect of early mobilization combined with early nutrition on acquired weakness in critically ill patients (EMAS): A dual-center, randomized controlled trial

AIM

The study aimed to investigate the effect of early mobilization combined with early nutrition (EMN) on intensive care unit-acquired weakness (ICU-AW) in intensive care unit (ICU) settings compared with early mobilization (EM) or routine care.

METHODS

A prospective, dual-center, randomized controlled trial was conducted. The control group underwent standard care without a pre-established routine for mobilization and nutrition. The EM group underwent early, individualized, progressive mobilization within 24 h of ICU admission. The EMN group underwent early mobilization, similar to the EM group plus guideline-based early nutrition (within 48 h of ICU admission). The primary outcome was the occurrence of ICU-AW at discharge from the ICU. Secondary outcomes included muscle strength, functional independence, organ failure, nutritional status, duration of mechanical ventilation (MV), length of ICU stay, and ICU mortality at ICU discharge.

RESULTS

A total of 150 patients were enrolled and equally distributed into the three groups. Patients undergoing routine care only were more susceptible to ICU-AW upon ICU discharge than those in the EM or EMN groups (16% vs. 2%; p = 0.014 for both), and had a lower Barthel Index than others (control vs. EM/EMN: 57.5 vs 70.0; p = 0.022). The EMN group had improved muscle strength (p = 0.028) and better nutritional status than the control group (p = 0.031). Both interventions were associated with a lower ICU-AW (EM vs. control: p = 0.027, OR [95% CI] = 0.066 [0.006-0.739]; EMN vs. control: p = 0.016, OR [95% CI] = 0.065 [0.007-0.607]).

CONCLUSION

EM and EMN had positive effects. There was little difference between the effects of EM and EMN, except for muscle strength improvement. Both EM and EMN may lead to a lower occurrence of ICU-AW and better functional independence than standard care. EMN might benefit nutritional status more than usual care and promote improvement in muscle strength.

Pulmonary function test and computed tomography features during follow-up after SARS, MERS and COVID-19: a systematic review and meta-analysis

Background

The COVID-19 pandemic follows severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronavirus epidemics. Some survivors of COVID-19 infection experience persistent respiratory symptoms, yet their cause and natural history remain unclear. Follow-up after SARS and MERS may provide a model for predicting the long-term pulmonary consequences of COVID-19.

Methods

This systematic review and meta-analysis aims to describe and compare the longitudinal pulmonary function test (PFT) and computed tomography (CT) features of patients recovering from SARS, MERS and COVID-19. Meta-analysis of PFT parameters (DerSimonian and Laird random-effects model) and proportion of CT features (Freeman-Tukey transformation random-effects model) were performed.

Findings

Persistent reduction in the diffusing capacity for carbon monoxide following SARS and COVID-19 infection is seen at 6 months follow-up, and 12 months after MERS. Other PFT parameters recover in this time. 6 months after SARS and COVID-19, ground-glass opacity, linear opacities and reticulation persist in over 30% of patients; honeycombing and traction dilatation are reported less often. Severe/critical COVID-19 infection leads to greater CT and PFT abnormality compared to mild/moderate infection.

Interpretation

Persistent diffusion defects suggestive of parenchymal lung injury occur after SARS, MERS and COVID-19 infection, but improve over time. After COVID-19 infection, CT features are suggestive of persistent parenchymal lung injury, in keeping with a post-COVID-19 interstitial lung syndrome. It is yet to be determined if this is a regressive or progressive disease.

Randomized Clinical Study of Temporary Transvenous Phrenic Nerve Stimulation in Difficult-to-Wean Patients

Rationale: Diaphragm dysfunction is frequently observed in critically ill patients with difficult weaning from mechanical ventilation. Objectives: To evaluate the effects of temporary transvenous diaphragm neurostimulation on weaning outcome and maximal inspiratory pressure. Methods: Multicenter, open-label, randomized, controlled study. Patients aged ⩾18 years on invasive mechanical ventilation for ⩾4 days and having failed at least two weaning attempts received temporary transvenous diaphragm neurostimulation using a multielectrode stimulating central venous catheter (bilateral phrenic stimulation) and standard of care (treatment) (n = 57) or standard of care (control) (n = 55). In seven patients, the catheter could not be inserted, and in seven others, pacing therapy could not be delivered; consequently, data were available for 43 patients. The primary outcome was the proportion of patients successfully weaned. Other endpoints were mechanical ventilation duration, 30-day survival, maximal inspiratory pressure, diaphragm-thickening fraction, adverse events, and stimulation-related pain. Measurements and Main Results: The incidences of successful weaning were 82% (treatment) and 74% (control) (absolute difference [95% confidence interval (CI)], 7% [-10 to 25]), P = 0.59. Mechanical ventilation duration (mean ± SD) was 12.7 ± 9.9 days and 14.1 ± 10.8 days, respectively, P = 0.50; maximal inspiratory pressure increased by 16.6 cm H₂O and 4.8 cm H₂O, respectively (difference [95% CI], 11.8 [5 to 19]), P = 0.001; and right hemidiaphragm thickening fraction during unassisted spontaneous breathing was +17% and -14%, respectively, P = 0.006, without correlation with changes in maximal inspiratory pressure. Serious adverse event frequency was similar in both groups. Median stimulation-related pain in the treatment group was 0 (no pain). Conclusions: Temporary transvenous diaphragm neurostimulation did not increase the proportion of successful weaning from mechanical ventilation. It was associated with a significant increase in maximal inspiratory pressure, suggesting reversal of the course of diaphragm dysfunction. Clinical trial registered with www.clinicaltrials.gov (NCT03096639) and the European Database on Medical Devices (CIV-17-06-020004).

Intensive Care Unit-Acquired Weakness in Patients With Extracorporeal Membrane Oxygenation Support: Frequency and Clinical Characteristics

Background

Intensive care unit-acquired weakness (ICU-AW) is common in critical illness patients and is well described. Extracorporeal membrane oxygenation (ECMO) is used as a life-saving method and patients with ECMO support often suffer more risk factors of ICU-AW. However, information on the frequency and clinical characteristics of ICU-AW in patients with ECMO support is lacking. Our study aims to clarify the frequency and characteristics of ICU-AW in ECMO patients.

Methods

We conducted a retrospective study, ICU-AW was diagnosed when patients were discharged with a Medical Research Council (MRC) sum score <48. Clinical information was collected from the case report forms. Univariable analysis, LASSO regression analysis, and logistic regression analysis were used to analyze the clinical data of individuals.

Results

In ECMO population, 40 (80%) patients diagnosed with ICU-AW. On univariable analysis, the ICU-AW group had higher Acute Physiology and Chronic Health Evaluation II (APACHE II) [13.9 (6.5-21.3) versus 21.1 (14.3-27.9), p = 0.005], longer deep sedation time [2 (0-7) versus 6.5 (3-11), p = 0.005], longer mechanical ventilation time [6.8 (2.6-9.3) versus 14.3 (6.6-19.3), p = 0.008], lower lowest albumin [26.7 (23.8-29.5) versus 22.1 (18.5-25.7), p < 0.001]. The LASSO analysis showed mechanical ventilation time, deep sedation time, deep sedation time during ECMO operation, APACHE II, and lowest albumin level were independent predictors of ICU-AW. To investigate whether ICU-AW occurs more frequently in the ECMO population, we performed a 1:1 matching with patients without ECMO and found there was no difference in the incidence of ICU-AW between the two groups. Logistic regression analysis of combined cohorts showed lowest albumin odds ratio (OR: 1.9, p = 0.024), deep sedation time (OR: 1.9, p = 0.022), mechanical ventilation time (OR: 2.0, p = 0.034), and APACHE II (OR: 2.3, p = 0.034) were independent risk factors of ICU-AW, but not ECMO.

Conclusion

The ICU-AW was common with a prevalence of 80% in the ECMO population. Mechanical ventilation time, deep sedation time, deep sedation time during ECMO operation, APACHE II, and lowest albumin level were risk factors of ICU-AW in ECMO population. The ECMO wasn't an independent risk factor of ICU-AW.

Prolonged Mechanical Ventilation: Outcomes and Management

The number of patients requiring prolonged mechanical ventilation (PMV) is increasing worldwide, placing a burden on healthcare systems. Therefore, investigating the pathophysiology, risk factors, and treatment for PMV is crucial. Various underlying comorbidities have been associated with PMV. The pathophysiology of PMV includes the presence of an abnormal respiratory drive or ventilator-induced diaphragm dysfunction. Numerous studies have demonstrated that ventilator-induced diaphragm dysfunction is related to increases in in-hospital deaths, nosocomial pneumonia, oxidative stress, lung tissue hypoxia, ventilator dependence, and costs. Thus far, the pathophysiologic evidence for PMV has been derived from clinical human studies and experimental studies in animals. Moreover, recent studies have demonstrated the outcome benefits of pharmacological agents and rehabilitative programs for patients requiring PMV. However, methodological limitations affected these studies. Controlled prospective studies with an adequate number of participants are necessary to provide evidence of the mechanism, prognosis, and treatment of PMV. The great epidemiologic impact of PMV and the potential development of treatment make this a key research field.

Severe but reversible impaired diaphragm function in septic mechanically ventilated patients

Background

Whether sepsis-associated diaphragm dysfunction may improve despite the exposure of mechanical ventilation in critically ill patients is unclear. This study aims at describing the diaphragm function time course of septic and non-septic mechanically ventilated patients.

Methods

Secondary analysis of two prospective observational studies of mechanically ventilated patients in whom diaphragm function was assessed twice: within the 24 h after intubation and when patients were switched to pressure support mode, by measuring the endotracheal pressure in response to bilateral anterior magnetic phrenic nerve stimulation (Ptr,stim). Change in diaphragm function was expressed as the difference between Ptr,stim measured under pressure support mode and Ptr,stim measured within the 24 h after intubation. Sepsis was defined according to the Sepsis-3 international guidelines upon inclusion. In a sub-group of patients, the right hemidiaphragm thickness was measured by ultrasound.

Results

Ninety-two patients were enrolled in the study. Sepsis upon intubation was present in 51 (55%) patients. In septic patients, primary reason for ventilation was acute respiratory failure related to pneumonia (37/51; 73%). In non-septic patients, main reasons for ventilation were acute respiratory failure not related to pneumonia (16/41; 39%), coma (13/41; 32%) and cardiac arrest (6/41; 15%). Ptr,stim within 24 h after intubation was lower in septic patients as compared to non-septic patients: 6.3 (4.9–8.7) cmH₂O vs. 9.8 (7.0–14.2) cmH₂O (p = 0.004), respectively. The median (interquartile) duration of mechanical ventilation between first and second diaphragm evaluation was 4 (2–6) days in septic patients and 3 (2–4) days in non-septic patients (p = 0.073). Between first and second measurements, the change in Ptr,stim was + 19% (− 13–61) in septic patients and − 7% (− 40–12) in non-septic patients (p = 0.005). In the sub-group of patients with ultrasound measurements, end-expiratory diaphragm thickness decreased in both, septic and non-septic patients. The 28-day mortality was higher in patients with decrease or no change in diaphragm function.

Conclusion

Septic patients were associated with a more severe but reversible impaired diaphragm function as compared to non-septic patients. Increase in diaphragm function was associated with a better survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01005-9.

Aldh1a1 and Scl25a30 in diaphragmatic dysfunction

New methods to prevent ventilator-induced diaphragmatic dysfunction (VIDD) are urgently needed, and the cellular basis of VIDD is poorly understood. This study evaluated whether transvenous phrenic nerve stimulation (PNS) could prevent VIDD in rabbits undergoing mechanical ventilation (MV) and explored whether oxidative stress-related genes might be candidate molecular markers for VIDD. Twenty-four adult male New Zealand white rabbits were allocated to control, MV, and PNS groups (n = 8 in each group). Rabbits in the MV and PNS groups underwent MV for 24 h. Intermittent bilateral transvenous PNS was performed in rabbits in the PNS group. Transdiaphragmatic pressure was recorded using balloon catheters. The diameters and cross-sectional areas (CSAs) of types I and II diaphragmatic fibers were measured using immunohistochemistry (IHC) techniques. Genes associated with VIDD were identified by RNA sequencing (RNA-seq), differentially expressed gene (DEG) analysis, and weighted gene co-expression network analysis (WGCNA). Reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and IHC analyses were carried out to verify the transcriptome profile. Pdi_60Hz, Pdi_80Hz, and Pdi_100Hz were significantly higher in the PNS group than in the MV group at 12 and 24 h (P < 0.05 at both time points). The diameters and CSAs of types I (slow-twitch) and II (fast-twitch) fibers were significantly larger in the PNS group than in the MV group (P < 0.05). RNA-seq, RT-PCR, Western blotting, and IHC experiments identified two candidate genes associated with VIDD: Aldh1a1 and Scl25a30. The MV group had significantly higher mRNA and protein expressions of Aldh1a1/ALDH1A1 and significantly lower mRNA and protein expressions of Scl25a30/SCL25A30 than the control or PNS groups (P < 0.05). We have identified two candidate genes involved in the prevention of VIDD by transvenous PNS. These two key genes may provide a theoretical basis for targeted therapy against VIDD.

Impact of inspiratory muscle strength on exercise capacity after lung transplantation

BACKGROUND AND PURPOSE

Though inspiratory muscle strength is essential for patients with respiratory disease, it is unclear whether the recovery of inspiratory muscle strength contributes to an exemplary achievement of exercise tolerance after lung transplantation (LTx). We aimed to elucidate the inspiratory muscle strength affects the recovery of exercise capacity after LTx.

METHODS

Recipients who underwent LTx between June 2017 and September 2018 were enrolled, and 6-min walking distance (6MWD), quadriceps force, inspiratory muscle strength (maximal inspiratory pressure [MIP]), and spirometry were evaluated at 3, 6, and 12 months after LTx. The relationships between inspiratory muscle strength and changes in physical performance were analyzed.

RESULTS

Nineteen recipients (mean age: 44.8 years, male: 32%) who completed all follow-ups were analyzed. At 3 months after LTx, mean MIP (88.4% predicted) and vital capacity (60.9% predicted), quadriceps force (QF; 2.1 N*m/kg), and 6MWD (504 m) were lower than normal values. After LTx, 6MWD significantly improved up to 12 months. From 3 to 6 months after LTx, changes in MIP were significantly associated with increases in 6MWD by univariate (r = 0.55, p = 0.02) and multivariate (β = 0.59, p = 0.01) regression analyses, whereas changes of QF in place of MIP were significantly associated with the recoveries of 6MWD from 6 to 12 months.

DISCUSSION

Improvements in MIP may impact the recovery of exercise capacity in the early phase after LTx. Factors that determine the improvement in exercise capacity following LTx may vary with postoperative time.

A Constructivist Grounded Theory of Staff Experiences Relating to Early Mobilisation of Mechanically Ventilated Patients in Intensive Care

Early mobilisation of mechanically ventilated patients has been suggested to be effective in mitigating muscle weakness, yet it is not a common practice. Understanding staff experiences is crucial to gain insights into what might facilitate or hinder its implementation. In this constructivist grounded theory study, data from two Scottish intensive care units were collected to understand healthcare staff experiences relating to early mobilisation in mechanical ventilation. Data included observations of mobilisation activities, individual staff interviews and two focus groups with multidisciplinary staff. Managing Risks emerged as the core category and was theorised using the concept of risk. The middle-range theory developed in this study suggests that the process of early mobilisation starts by staff defining patient status and includes a process of negotiating patient safety, which in turn enables performing accountable mobilisation within the dynamic context of an intensive care unit setting.

High-Intensity Inspiratory Muscle Training Improves Scalene and Sternocleidomastoid Muscle Oxygenation Parameters in Patients With Weaning Difficulties: A Randomized Controlled Trial

Background

Critically ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Inspiratory muscle training (IMT) can improve respiratory muscle strength. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown.

Aim

To compare changes in muscle oxygenation parameters of scalene and sternocleidomastoid inspiratory muscles during a standardized task between patients with weaning difficulties who received either high-intensity IMT (intervention) or sham low-intensity IMT (control).

Method

Forty-one patients performed daily IMT sessions (4 sets, 6–10 breaths) until weaning success or for 28 consecutive days. The training load was progressively adjusted in the intervention group (n = 22) to the highest tolerable load, whilst the control group (n = 19) kept training at 10% of their baseline maximal inspiratory pressure (PImax). Breathing characteristics (i.e., work and power of breathing, PoB), respiratory muscle function [i.e., PImax and forced vital capacity (FVC)] were measured during a standardized loaded breathing task against a load of 30% of baseline PImax before and after the IMT period. In addition, during the same loaded breathing task, absolute mean and nadir changes from baseline in local scalene and sternocleidomastoid muscle oxygen saturation index (Δ%StiO2) (an index of oxygen extraction) and nadir Δ%StiO2 normalized for the PoB were measured by near-infrared spectroscopy.

Results

At post measures, only the intervention group improved mean PoB compared to pre measures (Pre: 0.42 ± 0.33 watts, Post: 0.63 ± 0.51watts, p-value &lt; 0.01). At post measures, both groups significantly improved nadir scalene muscles StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) compared to pre measurements and the improvement was not significant different between groups (p-value = 0.40). However, at post measures, nadir sternocleidomastoid muscle StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) was significantly greater improved in the intervention group (mean difference: +18.4, 95%CI: −1.4; 38.1) compared to the control group (mean difference: +3.7, 95%CI: −18.7; 26.0, between group p-value &lt; 0.01). Both groups significantly improved PImax (Intervention: +15 ± 13 cmH2O p-value &lt; 0.01, Control: +13 ± 15 cmH2O p-value &lt; 0.01). FVC only significantly improved in the intervention group (+0.33 ± 0.31 L p &lt; 0.01) report also change in control group.

Conclusion

This exploratory study suggests that high-intensity IMT induces greater improvements in scalene and sternocleidomastoid muscle oxygenation parameters attributed for oxygen delivery, utilization and oxygen saturation index compared to low-intensity IMT in patients with weaning difficulties.

Effective Mechanical Insufflation-Exsufflation in a Patient With Difficulty in Sputum Discharge and Intensive Care Unit-Acquired Weakness: A Case Report

Intensive care unit-acquired weakness (ICU-AW), a common complication in critically ill patients, may result in diaphragmatic dysfunction, which delays weaning from artificial ventilators. Here, we present the case of a patient with difficulty in sputum discharge due to ICU-AW. In the ICU, postural drainage sputum aspiration by bronchoscopy and squeezing were performed daily, but the patient’s condition did not resolve. Mechanical insufflation-exsufflation (MI-E) enabled the sputum to move to the main bronchus from the peripheral bronchi, and suctioning using a bronchoscope was no longer necessary. However, the presence of sputum persisted, and MI-E was necessary after weaning, proving crucial in treating the patient with sputum discharge difficulty complicated by ICU-AW after being removed from an artificial ventilator. MI-E can be useful for patients with difficulty in sputum discharge due to ICU-AW; however, the weaning process may be prolonged in such cases.

Lung- and Diaphragm-Protective Ventilation by Titrating Inspiratory Support to Diaphragm Effort: A Randomized Clinical Trial

OBJECTIVES

Lung- and diaphragm-protective ventilation is a novel concept that aims to limit the detrimental effects of mechanical ventilation on the diaphragm while remaining within limits of lung-protective ventilation. The premise is that low breathing effort under mechanical ventilation causes diaphragm atrophy, whereas excessive breathing effort induces diaphragm and lung injury. In a proof-of-concept study, we aimed to assess whether titration of inspiratory support based on diaphragm effort increases the time that patients have effort in a predefined "diaphragm-protective" range, without compromising lung-protective ventilation.

DESIGN

Randomized clinical trial.

SETTING

Mixed medical-surgical ICU in a tertiary academic hospital in the Netherlands.

PATIENTS

Patients (n = 40) with respiratory failure ventilated in a partially-supported mode.

INTERVENTIONS

In the intervention group, inspiratory support was titrated hourly to obtain transdiaphragmatic pressure swings in the predefined "diaphragm-protective" range (3-12 cm H2O). The control group received standard-of-care.

MEASUREMENTS AND MAIN RESULTS

Transdiaphragmatic pressure, transpulmonary pressure, and tidal volume were monitored continuously for 24 hours in both groups. In the intervention group, more breaths were within "diaphragm-protective" range compared with the control group (median 81%; interquartile range [64-86%] vs 35% [16-60%], respectively; p < 0.001). Dynamic transpulmonary pressures (20.5 ± 7.1 vs 18.5 ± 7.0 cm H2O; p = 0.321) and tidal volumes (7.56 ± 1.47 vs 7.54 ± 1.22 mL/kg; p = 0.961) were not different in the intervention and control group, respectively.

CONCLUSIONS

Titration of inspiratory support based on patient breathing effort greatly increased the time that patients had diaphragm effort in the predefined "diaphragm-protective" range without compromising tidal volumes and transpulmonary pressures. This study provides a strong rationale for further studies powered on patient-centered outcomes.

Noninvasive respiratory support following extubation in critically ill adults: a systematic review and network meta-analysis

PURPOSE

Systematic review and network meta-analysis to investigate the efficacy of noninvasive respiratory strategies, including noninvasive positive pressure ventilation (NIPPV) and high-flow nasal cannula (HFNC), in reducing extubation failure among critically ill adults.

METHODS

We searched databases from inception through October 2021 for randomized controlled trials (RCTs) evaluating noninvasive respiratory support therapies (NIPPV, HFNC, conventional oxygen therapy, or a combination of these) following extubation in critically ill adults. Two reviewers performed screening, full text review, and extraction independently. The primary outcome of interest was reintubation. We used GRADE to rate the certainty of our findings.

RESULTS

We included 36 RCTs (6806 patients). Compared to conventional oxygen therapy, NIPPV (OR 0.65 [95% CI 0.52-0.82]) and HFNC (OR 0.63 [95% CI 0.45-0.87]) reduced reintubation (both moderate certainty). Sensitivity analyses showed that the magnitude of the effect was highest in patients with increased baseline risk of reintubation. As compared to HFNC, no difference in incidence of reintubation was seen with NIPPV (OR 1.04 [95% CI 0.78-1.38], low certainty). Compared to conventional oxygen therapy, neither NIPPV (OR 0.8 [95% CI 0.61-1.04], moderate certainty) or HFNC (OR 0.9 [95% CI 0.66-1.24], low certainty) reduced short-term mortality. Consistent findings were demonstrated across multiple subgroups, including high- and low-risk patients. These results were replicated when evaluating noninvasive strategies for prevention (prophylaxis), but not in rescue (application only after evidence of deterioration) situations.

CONCLUSIONS

Our findings suggest that both NIPPV and HFNC reduced reintubation in critically ill adults, compared to conventional oxygen therapy. NIPPV did not reduce incidence of reintubation when compared to HFNC. These findings support the preventative application of noninvasive respiratory support strategies to mitigate extubation failure in critically ill adults, but not in rescue conditions.

Can Cardiopulmonary Rehabilitation Facilitate Weaning of Extracorporeal Membrane Oxygenation (CaRe-ECMO)? Study Protocol for a Prospective Multidisciplinary Randomized Controlled Trial

Background: Mortality of patients suffering from critical illness has been dramatically improved with advanced technological development of extracorporeal membrane oxygenation (ECMO) therapy. However, the majority of ECMO-supported patients failed to wean from ECMO therapy. As one of several options, cardiopulmonary rehabilitation serves as effective intervention in the improvement of cardiovascular and respiratory function in various major critical illness. Nonetheless, its role in facilitating ECMO weaning has not yet been explored. The purpose of this study is to investigate the effectiveness of cardiopulmonary rehabilitation on rate of ready for ECMO weaning in ECMO-supported patients (CaRe-ECMO).

Methods: The CaRe-ECMO trial is a randomized controlled, parallel group, clinical trial. This trial will be performed in a minimum number of 366 ECMO-supported eligible patients. Patients will be randomly assigned to either: (1) the CaRe-ECMO group, which will be treated with usual care including pharmacotherapy, non-pharmacotherapy, and specific nursing for ECMO therapy and the CaRe-ECMO program; or (2) the control group, which will receive usual care only. The CaRe-ECMO program consists of protocolized positioning, passive range of motion (PROM) training, neuromuscular electrical stimulation (NMES), surface electrical phrenic nerve stimulation (SEPNS), and pulmonary rehabilitation. The primary outcome of the CaRe-ECMO trial is the rate of ready for ECMO weaning at CaRe-ECMO day 7 (refers to 7 days after the CaRe-ECMO program initiation). Secondary outcomes include rate of ECMO and mechanical ventilation weaning, total length in day of ready for ECMO weaning, ECMO weaning and mechanical ventilation, all-cause mortality, rate of major post-ECMO complications, ECMO unit length of stay (LOS) and hospital LOS, total cost for hospitalization, cerebral performance category (CPC), activities of daily living (ADL), and health-related quality of life (HRQoL).

Discussion: The CaRe-ECMO is designed to answer the question “whether cardiopulmonary rehabilitation can facilitate weaning of ECMO (CaRe-ECMO).” Should the implementation of the CaRe-ECMO program result in superior primary and secondary outcomes as compared to the controls, specifically the add-on effects of cardiopulmonary rehabilitation to the routine ECMO practice for facilitating successful weaning, the CaRe-ECMO trial will offer an innovative treatment option for ECMO-supported patients and meaningfully impact on the standard care in ECMO therapy.

Clinical Trial Registration:ClinicalTrials.gov, identifier: NCT05035797.

Diaphragm Ultrasound in Cardiac Surgery: State of the Art

In cardiac surgery, patients are at risk of phrenic nerve injury, which leads to diaphragm dysfunction and acute respiratory failure. Diaphragm dysfunction (DD) is relatively frequent in cardiac surgery and particularly affects patients after coronary artery bypass graft. The onset of DD affects patients’ prognosis in term of weaning from mechanical ventilation and hospital length of stay. The authors present a narrative review about diaphragm physiology, techniques used to assess diaphragm function, and the clinical application of diaphragm ultrasound in patients undergoing cardiac surgery.

Magnetic twitch assessment of diaphragm and quadriceps weakness in critically ill mechanically ventilated patients

Critically ill mechanically ventilated (MV) patients develop significant muscle weakness, which has major clinical consequences. There remains uncertainty, however, regarding the severity of leg weakness, the precise relationship between muscle strength and thickness, and the risk factors for weakness in MV patients. We therefore measured both diaphragm (PdiTw) and quadriceps (QuadTw) strength in MV patients using magnetic stimulation and compared strength to muscle thickness. Both PdiTw and QuadTw were profoundly reduced for MV patients, with PdiTw 19 % of normal and QuadTw 6% of normal values. There was a poor correlation between strength and thickness for both muscles, with thickness often remaining in the normal range when strength was severely reduced. Regression analysis revealed reductions in PdiTw correlated with presence of infection (p = 0.006) and age (p = 0.007). QuadTw best correlated with duration of MV (p = 0.036). Limb muscles are profoundly weak in critically ill patients, with a severity that mirrors the level of weakness observed in the diaphragm.

Electrophysiological assessment of respiratory function

While the traditional lung function tests are used to assess lung capacity and pulmonary function, they cannot evaluate respiratory driving function and the integrity of the conduction pathway from the central nervous system to the respiratory motor neuron in the spinal cord and to the diaphragm. The inspiratory trigger is sent from the central nervous system through the phrenic nerve and drives the diaphragm to generate inspiratory movement. Therefore, phrenic nerve stimulation and diaphragmatic electromyography are two fundamental methods to assess respiratory function. There are several useful tools to assess respiratory motor system including electrical or magnetic phrenic nerve stimulation, diaphragmatic needle electromyography, and diaphragmatic ultrasound. By these means, physicians can assess current respiratory status in different neurological diseases that affect respiratory muscles, follow-up of the severity of respiratory impairment, help to predict the chance of successfully weaning from ventilatory support, and confirm clinical diagnoses such as diaphragmatic myoclonus. Although some of these tests require special training, applying these neurophysiological assessments in clinical practice is highly recommended.

The physiological underpinnings of life-saving respiratory support

Treatment of respiratory failure has improved dramatically since the polio epidemic in the 1950s with the use of invasive techniques for respiratory support: mechanical ventilation and extracorporeal respiratory support. However, respiratory support is only a supportive therapy, designed to "buy time" while the disease causing respiratory failure abates. It ensures viable gas exchange and prevents cardiorespiratory collapse in the context of excessive loads. Because the use of invasive modalities of respiratory support is also associated with substantial harm, it remains the responsibility of the clinician to minimize such hazards. Direct iatrogenic consequences of mechanical ventilation include the risk to the lung (ventilator-induced lung injury) and the diaphragm (ventilator-induced diaphragm dysfunction and other forms of myotrauma). Adverse consequences on hemodynamics can also be significant. Indirect consequences (e.g., immobilization, sleep disruption) can have devastating long-term effects. Increasing awareness and understanding of these mechanisms of injury has led to a change in the philosophy of care with a shift from aiming to normalize gases toward minimizing harm. Lung (and more recently also diaphragm) protective ventilation strategies include the use of extracorporeal respiratory support when the risk of ventilation becomes excessive. This review provides an overview of the historical background of respiratory support, pathophysiology of respiratory failure and rationale for respiratory support, iatrogenic consequences from mechanical ventilation, specifics of the implementation of mechanical ventilation, and role of extracorporeal respiratory support. It highlights the need for appropriate monitoring to estimate risks and to individualize ventilation and sedation to provide safe respiratory support to each patient.

Diaphragm Ultrasound in the Evaluation of Diaphragmatic Dysfunction in Lung Disease

The diaphragm is the most important respiratory muscle, and its function may be limited by acute and chronic diseases. A diaphragmatic ultrasound, which quantifies dysfunction through different approaches, is useful in evaluating work of breathing and diaphragm atrophy, predicting successful weaning, and diagnosing critically ill patients. This technique has been used to determine reduced diaphragmatic function in patients with chronic obstructive pulmonary disease and interstitial diseases, while in those with COVID-19, diaphragmatic ultrasound has been used to predict weaning failure from mechanical ventilation.

Unanticipated Profound Paralysis and Sugammadex Dosing Implications After Videoscopic Thoracic Surgery

A bedridden patient with empyema presented for thoracoscopic decortication. During the procedure, despite a post-tetanic count (PTC) of 0 via calibrated quantitative neuromuscular monitoring, persistent diaphragmatic movement impaired operating conditions, so rocuronium was re-dosed. After surgery, the patient had 0 PTC. Sugammadex was titrated to achieve baseline neuromuscular strength, monitoring the effect of each 200-mg dose. Ultimately, 1200 mg was required to achieve baseline strength. We describe monitor troubleshooting, considerations with unexpectedly deep neuromuscular blockade, the importance of routine quantitative neuromuscular monitoring, and one strategy for sugammadex reversal in patients with profound paralysis outside of the standard dosing guidelines.

Diaphragmatic Point-of-Care Ultrasound in COVID-19 Patients in the Emergency Department-A Proof-of-Concept Study

Background: Lung Ultrasound Evaluation (LUS) is usefully applied in the Emergency Department (ED) to patients with suspected or confirmed COVID-19. Diaphragmatic Ultrasound (DUS) may provide additional insight into ventilatory function. This proof-of-concept study aimed to evaluate the feasibility of LUS and DUS in a third level ED during the COVID-19 pandemic. Methods: Adult patients presenting with COVID-19 symptoms were eligible. After the physical examination, both LUS and DUS (i.e., diaphragmatic motion and thickness) were performed. All patients were followed after 30 days to determine their need for ventilation, admission, and/or a new ED evaluation after discharge. The diagnostic accuracies of diaphragm measurements in assessing the risk of the 30-day outcome were calculated as well as the measurements’ usefulness. Bland–Altman plots were used for comparing bedside and off-line diaphragm measurements. Results: 118 patients were enrolled. Median thickness and motion were 1.7 mm (iqr 0.4) and 1.8 cm (iqr 0.7), respectively, with a mean difference of 0.009 mm (95% CI −0.037–0.056 mm) and −0.051 cm (95% CI −0.108–0.006 cm), respectively. The 30-day outcome was associated with an increase in thickness (OR 5.84, 95% CI 0.96–35.4), and a lower motion (OR 0.49, 95% CI 0.2–1.21). Conclusion: DUS seemed to be feasible and reliable in the ED in a population of patients presenting with symptoms related to COVID-19 infection.

Ultrasound Protocols to Assess Skeletal and Diaphragmatic Muscle in People Who Are Critically Ill: A Systematic Review

This study aims to review published studies that use protocols and ultrasound measurements to evaluate skeletal and diaphragmatic muscles in patients who are critically ill. We searched for references on databases through September 2020 and included in our systematic review studies that used muscular ultrasound to assess skeletal or diaphragm muscles in patients who are critically ill. Seventy-six studies were included, 32 (1720 patients) using skeletal-muscle ultrasound and 44 (2946 patients) using diaphragmatic-muscle ultrasound, with a total of 4666 patients. The population is predominantly adult men. As for designs, most studies (n = 62) were cohort studies. B-mode B was dominant in the evaluations. Medium-to-high frequency bands were used in the analysis of peripheral muscles and medium-to-low frequency bands for diaphragmatic muscles. Evaluation of the echogenicity, muscle thickness and pennation angle of the muscle was also reported. These variables are important in the composition of the diagnosis of muscle loss. Studies demonstrate great variability in their protocols, and sparse description of the important variables that can directly interfere with the quality and validity of these measures. Therefore, a document is needed that standardizes these parameters for ultrasound assessment in patients who are critically ill.

Ultrasound assessment of the diaphragm during the first days of mechanical ventilation compared to spontaneous respiration: a comparative study

INTRODUCTION

In critically ill patients, the diaphragm is subject to several aggressions mainly those induced by mechanical ventilation (MV). Currently, diaphragmatic ultrasound has become the most useful bedside for the clinician to evaluate diaphragm contractility.

AIM

  To examine the effects of MV on the diaphragm contractility during the first days of ventilation.

METHODS

Two groups of subjects were studied: a study group (n=30) of adults receiving MV versus a control group (n=30) of volunteers on spontaneous ventilation (SV). Using an ultrasound device, we compared the diaphragmatic thickening fraction (DTF). Secondly, we analysed the relationship between DTF and weaning.

RESULTS

comparatively to SV group, patients of MV group have a higher end expiratory diameter (EED) (2.09 ± 0.6 vs. 1.76 ± 0.32 mm, p=0.01) and a lower DTF (39.9 ± 12.5%  vs.  49.0 ± 20.5%, p=0.043). Fourteen among the 30 ventilated patients successfully weaned. No significant correlation was shown between DTF and weaning duration (Rho= - 0.464, p=0.09). A DTF value > 33% was near to be significantly associated with weaning success (OR=2; 95% CI= [1.07-3.7], p=0.05) with a sensitivity at 85.7%.

CONCLUSIONS

diaphragmatic contractility was altered from the first days of MV. A DTF value >32,7% was associated to the weaning success and that may be useful to predict successful weaning with sensitivity at 85.7%.

Handgrip strength to predict extubation outcome: a prospective multicenter trial

BACKGROUND

ICU-acquired weakness (ICUAW) has been shown to be associated with prolonged duration of mechanical ventilation and extubation failure. It is usually assessed through Medical Research Council (MRC) score, a time-consuming score performed by physiotherapists. Handgrip strength (HG) can be monitored very easily at the bedside. It has been shown to be a reproducible and reliable marker of global muscular strength in critical care patients. We sought to test if muscular weakness, as assessed by handgrip strength, was associated with extubation outcome.

METHODS

Prospective multicenter trial over an 18 months period in six mixed ICUs. Adults receiving mechanical ventilation for at least 48 h were eligible. Just before weaning trial, HG, Maximal Inspiratory Pressure (MIP), Peak Cough Expiratory Flow (PCEF) and Medical Research Council (MRC) score were registered. The attending physicians were unaware of the tests results and weaning procedures were conducted according to guidelines. Occurrence of unscheduled reintubation, non-invasive ventilation (NIV) or high-flow nasal continuous oxygen (HFNC) because of respiratory failure within 7 days after extubation defined extubation failure. The main outcome was the link between HG and extubation outcome.

RESULTS

233 patients were included. Extubation failure occurred in 51 (22.5%) patients, 39 (17.2%) required reintubation. Handgrip strength was 12 [6-20] kg and 12 [8-20] kg, respectively, in extubation success and failure (p = 0.85). There was no association between extubation outcome and MRC score, MIP or PCEF. Handgrip strength was well correlated with MRC score (r = 0.718, p < 0.0001). ICU and hospital length of stay were significantly higher in the subset of patients harboring muscular weakness as defined by handgrip performed at the first weaning trial (respectively, 15 [10-25] days vs. 11 [7-17] days, p = 0.001 and 34 [19-66] days vs. 22 [15-43] days, p = 0.002).

CONCLUSION

No association was found between handgrip strength and extubation outcome. Whether this was explained by the appropriateness of the tool in this specific setting, or by the precise impact of ICUAW on extubation outcome deserves to be further evaluated. Trial registration Clinical Trials; NCT02946502, 10/27/2016, URL: https://clinicaltrials.gov/ct2/results?cond=&term=gripwean&cntry=&state=&city=&dist=.

Positive end-expiratory pressure affects geometry and function of the human diaphragm

Positive end-expiratory pressure (PEEP) is routinely applied in mechanically ventilated patients to improve gas exchange and respiratory mechanics by increasing end-expiratory lung volume (EELV). In a recent experimental study in rats, we demonstrated that prolonged application of PEEP causes diaphragm remodeling, especially longitudinal muscle fiber atrophy. This is of potential clinical importance, as the acute withdrawal of PEEP during ventilator weaning decreases EELV and thereby stretches the adapted, longitudinally atrophied diaphragm fibers to excessive sarcomere lengths, having a detrimental effect on force generation. Whether this series of events occurs in the human diaphragm is unknown. In the current study, we investigated if short-term application of PEEP affects diaphragm geometry and function, which are prerequisites for the development of longitudinal atrophy with prolonged PEEP application. Nineteen healthy volunteers were noninvasively ventilated with PEEP levels of 2, 5, 10, and 15 cmH₂O. Magnetic resonance imaging was performed to investigate PEEP-induced changes in diaphragm geometry. Subjects were instrumented with nasogastric catheters to measure diaphragm neuromechanical efficiency (i.e., diaphragm pressure normalized to its electrical activity) during tidal breathing with different PEEP levels. We found that increasing PEEP from 2 to 15 cmH₂O resulted in a caudal diaphragm displacement (19 [14-26] mm, P < 0.001), muscle shortening in the zones of apposition (20.6% anterior and 32.7% posterior, P < 0.001), increase in diaphragm thickness (36.4% [0.9%-44.1%], P < 0.001) and reduction in neuromechanical efficiency (48% [37.6%-56.6%], P < 0.001). These findings demonstrate that conditions required to develop longitudinal atrophy in the human diaphragm are present with the application of PEEP.NEW & NOTEWORTHY We demonstrate that PEEP causes changes in diaphragm geometry, especially muscle shortening, and decreases in vivo diaphragm contractile function. Thus, prerequisites for the development of diaphragm longitudinal muscle atrophy are present with the acute application of PEEP. Once confirmed in ventilated critically ill patients, this could provide a new mechanism for ventilator-induced diaphragm dysfunction and ventilator weaning failure in the intensive care unit (ICU).

Qualitative and quantitative muscle ultrasound changes in patients with COVID-19-related ARDS

OBJECTIVES

Severe forms of the novel coronavirus-19 (COVID-19) are associated with systemic inflammation and hypercatabolism. The aims of this study were to compare the time course of the size and quality of both rectus femoris and diaphragm muscles between critically ill, COVID-19 survivors and non-survivors and to explore the correlation between the change in muscles size and quality with the amount of nutritional support delivered and the cumulative fluid balance.

METHODS

This was a prospective observational study in the general intensive care unit (ICU) of a tertiary care hospital for COVID-19. The right rectus femoris cross-sectional area and the right diaphragm thickness, as well as their echo densities were assessed within 24 h from ICU admission and on day 7. We recorded anthropometric and biochemical data, respiratory mechanics and gas exchange, daily fluid balance, and the number of calories and proteins administered.

RESULTS

Twenty-eight patients were analyzed (65 ± 10 y of age; 80% men, body mass index 30 ± 7.8 kg/m²). Rectus femoris and diaphragm sizes were significantly reduced at day 7 (median = -26.1 [interquartile ratio [IQR], = -37.8 to -15.2] and -29.2% [-37.8% to -19.6%], respectively) and this reduction was significantly higher in non-survivors. Both rectus femoris and diaphragm echo density were significantly increased at day 7, with a significantly higher increase in non-survivors. The change in both rectus femoris and diaphragm size at day 7 was related to the cumulative protein deficit (R = 0.664, P < 0.001 and R = 0.640, P < 0.001, respectively), whereas the change in rectus femoris and diaphragm echo density was related to the cumulative fluid balance (R = 0.734, P < 0.001 and R = 0.646, P < 0.001, respectively).

CONCLUSIONS

Early changes in muscle size and quality seem related to the outcome of critically ill COVID-19 patients, and to be influenced by nutritional and fluid management strategies.

Inspiratory muscle training in intensive care unit patients: An international cross-sectional survey of physiotherapist practice

BACKGROUND

Inspiratory muscle training is safe and effective in reversing inspiratory muscle weakness and improving outcomes in patients who have experienced prolonged mechanical ventilation in the intensive care unit (ICU). The degree of worldwide implementation of inspiratory muscle training in such patients has not been investigated.

OBJECTIVES

The objectives of this study were to describe the current practice of inspiratory muscle training by intensive care physiotherapists and investigate barriers to implementation in the intensive care context and additionally to determine if any factors are associated with the use of inspiratory muscle training in patients in the ICU and identify preferred methods of future education.

METHOD

Online cross-sectional surveys of intensive care physiotherapists were conducted using voluntary sampling. Multivariate logistic regression analysis was used to identify factors associated with inspiratory muscle training use in patients in the ICU.

RESULTS

Of 360 participants, 63% (95% confidence interval [CI] = 58 to 68) reported using inspiratory muscle training in patients in the ICU, with 69% (95% CI = 63 to 75) using a threshold device. Only 64% (95% CI = 58 to 70) of participants who used inspiratory muscle training routinely assessed inspiratory muscle strength. The most common barriers to implementing inspiratory muscle training sessions in eligible patients were sedation and delirium. Participants were 4.8 times more likely to use inspiratory muscle training in patients if they did not consider equipment a barrier and were 4.1 times more likely to use inspiratory muscle training if they aware of the evidence for this training in these patients. For education about inspiratory muscle training, 41% of participants preferred online training modules.

CONCLUSION

In this first study to describe international practice by intensive care therapists, 63% reported using inspiratory muscle training. Improving access to equipment and enhancing knowledge of inspiratory muscle training techniques could improve the translation of evidence into practice.

Mechanical ventilation at the time of heart transplantation and associations with clinical outcomes

AIMS

The impact of mechanical ventilation (MV) at the time of heart transplantation is not well understood. In addition, MV was recently removed as a criterion from the new US heart transplantation allocation system. We sought to assess for the association between MV at transplantation and 1-year mortality.

METHODS AND RESULTS

We utilized the United Network for Organ Sharing database and included all adult, single organ heart transplantations from 1990 to 2019. We utilized multivariable logistic regression adjusting for demographics, comorbidities, and markers of clinical acuity. We identified 60 980 patients who underwent heart transplantation, 2.4% (n = 1431) of which required MV at transplantation. Ventilated patients were more likely to require temporary mechanical support, previous dialysis, and had a shorter median waitlist time (21 vs. 95 days, P < 0.001). At 1 year, the mortality was 33.7% (n = 484) for ventilated patients and 11.7% (n = 6967) for those not ventilated at the time of transplantation (log-rank P < 0.001). After multivariable adjustment, patients requiring MV continued to have a substantially higher 90-day [odds ratio (OR) 3.20, 95% confidence interval (CI): 2.79-3.66, P < 0.001] and 1-year mortality (OR 2.67, 95% CI: 2.36-3.03, P < 0.001). For those that survived to 90 days, the adjusted mortality at 1 year continued to be higher (OR 1.48, 95% CI: 1.16-1.89, P = 0.002).

CONCLUSION

We found a strong association between the presence of MV at heart transplantation and 90-day and 1-year mortality. Future studies are needed to identify which patients requiring MV have reasonable outcomes, and which are associated with substantially poorer outcomes.

Assessment of magnetic flux density properties of electromagnetic noninvasive phrenic nerve stimulations for environmental safety in an ICU environment

Diaphragm weakness affects up to 60% of ventilated patients leading to muscle atrophy, reduction of muscle fiber force via muscle fiber injuries and prolonged weaning from mechanical ventilation. Electromagnetic stimulation of the phrenic nerve can induce contractions of the diaphragm and potentially prevent and treat loss of muscular function. Recommended safety distance of electromagnetic coils is 1 m. The aim of this study was to investigate the magnetic flux density in a typical intensive care unit (ICU) setting. Simulation of magnetic flux density generated by a butterfly coil was performed in a Berlin ICU training center with testing of potential disturbance and heating of medical equipment. Approximate safety distances to surrounding medical ICU equipment were additionally measured in an ICU training center in Bern. Magnetic flux density declined exponentially with advancing distance from the stimulation coil. Above a coil distance of 300 mm with stimulation of 100% power the signal could not be distinguished from the surrounding magnetic background noise. Electromagnetic stimulation of the phrenic nerve for diaphragm contraction in an intensive care unit setting seems to be safe and feasible from a technical point of view with a distance above 300 mm to ICU equipment from the stimulation coil.