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

Diaphragm neurostimulation in mechanical ventilation: current status and future prospects

INTRODUCTION

Diaphragm neurostimulation is a muscle stimulation technique that, through electrodes placed directly on or at the vicinity of the phrenic nerves, induces diaphragm contractions independently of the patient's cooperation. Recently, the technical development of temporary diaphragm neurostimulation devices has paved the way for a new era in the management of critically ill patients.

AREAS COVERED

In this review, we describe the latest technical developments in diaphragm neurostimulation and its physiological effects. We searched MEDLINE of experimental and clinical studies in English language published from database inception until 31 October 2024. We also discuss the advances in terms of patients centered outcomes and the key areas for improvement. Lastly, we introduce possible future directions and the novel improvements in patient care.

EXPERT OPINION

The research on diaphragm neurostimulation promise as an emerging intervention which addresses common complications associated with mechanical ventilation. Large-scale clinical trials are necessary to validate diaphragm neurostimulation efficacy and safety in humans, establish treatment protocols, and determine cost-effectiveness, all of which are essential for diaphragm neurostimulation to be widely accepted in clinical practice.

Early mobilization after skin graft for burn injury in adults

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effects of early mobilization after skin graft for burn injury in adults.

Respiratory muscle ultrasound echo characteristics and weaning outcomes in mechanically ventilated patients with sepsis: a prospective observational study

AIM

This study aimed to determine the relationship between changes in the ultrasound echo intensity of respiratory muscles and weaning outcomes in mechanically ventilated patients with sepsis.

METHODS

We prospectively observed patients with sepsis receiving mechanical ventilation admitted to the Department of Critical Care Medicine at our hospital, and categorized them into weaning success (n = 75) and weaning failure (n = 35) groups according to their weaning outcomes. The baseline respiratory muscle echo intensity of the patients was observed, and the relationship between the respiratory muscle ultrasonographic echo characteristics and weaning outcomes was evaluated.

RESULTS

Baseline respiratory muscle echo intensity was significantly higher in the weaning failure group than in the weaning success group. The incidence of respiratory muscle echoes during mechanical ventilation was significantly higher in the weaning failure group than in the weaning success group. The respiratory muscle echo characteristics changed after ICU admission. Increased respiratory muscle echo intensity was detected earlier and more readily in patients with weaning failure than in those with respiratory muscle atrophy, and enhanced respiratory muscle echo was associated with a decrease in the incidence of cumulative weaning success.

CONCLUSION

Mechanically ventilated patients with sepsis with failed weaning had higher respiratory muscle echo intensities than those in the weaning success group. Futhermore, there was an association between the respiratory muscle echo intensity and weaning outcomes.

Physiological comparison of noninvasive ventilation and high-flow nasal oxygen on inspiratory efforts and tidal volumes after extubation: a randomized crossover trial

BACKGROUND

Extubation failure leading to reintubation is associated with high mortality. In patients at high-risk of extubation failure, clinical practice guidelines recommend prophylactic non-invasive ventilation (NIV) over high-flow nasal oxygen (HFNO) immediately after extubation. However, the physiological effects supporting the beneficial effect of NIV have been poorly explored. We hypothesized that NIV may reduce patient inspiratory efforts to a greater extent than HFNO after extubation.

METHODS

In a prospective physiological study, patients at high-risk of extubation failure (> 65 years old or underlying cardiac or respiratory disease) were included to receive after planned extubation prophylactic NIV and HFNO in a randomized crossover order, followed by standard oxygen. Inspiratory efforts were assessed by calculation of the simplified esophageal pressure-time-product per minute (sPTPes in cmH2O s/min). Tidal volumes, distribution and homogeneity of ventilation were estimated using electrical impedance tomography.

RESULTS

Twenty patients were retained in the analysis. Inspiratory efforts were lower with NIV than with HFNO (sPTPes 196 cm H2O s/min [116-234] vs. 220 [178-327], p < 0.001) whereas tidal volumes were larger with NIV than with HFNO (8.4 mL/kg of predicted body weight [6.7-9.9] vs. 6.9 [5.3-8.6], p = 0.005). There was a non-significant increase in dorsal region ventilation under NIV compared to HFNO.

CONCLUSIONS

In patients at high-risk of extubation failure, prophylactic NIV significantly decreased inspiratory efforts with increased tidal volumes compared to HFNO. The clinical benefits of NIV to prevent reintubation in patients at high-risk may be mediated by these physiological effects. Trial registration Clinicaltrials.gov: ID NCT04036175), retrospectively registered 17 June 2019.

ARDS Weaning: The Impact of Abnormal Breathing Patterns Detected by Electric Tomography Impedance and Respiratory Mechanics Monitoring

Background: After the improvement of the initial phase of ARDS, when the patients begin spontaneous breathing and weaning from mechanical ventilation, some patients may present abnormal breathing patterns, whose evaluation of the repercussions were poorly studied. This study proposed to evaluate abnormal breathing patterns through the use of electrical impedance tomography (EIT), and clinical, respiratory mechanics, and ventilatory parameters according to the types of weaning from mechanical ventilation. Methods: This was a prospective cohort study of subjects with ARDS who were considered able to be weaned from mechanical ventilation in the clinical-surgical ICU. Weaning types were defined as simple, difficult, and prolonged weaning. EIT, ventilatory, lung mechanics, and clinical data were collected. Data were collected at baseline in a controlled ventilatory mode and, after neuromuscular blocker withdrawal, data were collected after 30 min, 2 h, and 24 h. EIT parameter analysis was performed for ventilation distribution in the lung regions, pendelluft, breath-stacking, reverse-trigger, double-trigger, and asynchrony index. Results: The study included 25 subjects who were divided into 3 groups (9/25 simple, 8/25 difficult, and 8/25 prolonged weaning). The prolonged weaning group showed more delirium, ICU-acquired weakness, stay in ICU, and hospital and ICU mortality. During the change from controlled to spontaneous mode, we observed increased tidal volumes and driving pressures, which were mainly found in the prolonged weaning group when compared with the simple weaning group. The prolonged weaning group showed a higher flow index, more asynchronies during volume-assisted ventilation, a higher incidence of pendelluft, and redistribution of ventilation to posterior regions visualized by EIT. Conclusions: The present study showed abnormal breathing patterns in the prolonged weaning group. The clinical occult findings of abnormal breathing patterns could be monitored, mainly through EIT and with better assessment of pulmonary mechanics.

Monitoring and preserving diaphragmatic function in mechanical ventilation

PURPOSE OF REVIEW

This review summarizes the evidence on clinical outcomes related to diaphragm dysfunction, providing an overview on available monitoring tools and strategies for its prevention and treatment.

RECENT FINDINGS

Long-term adverse functional outcomes in intensive care survivors are well documented, especially in patients with prolonged mechanical ventilation. Because diaphragm weakness is highly prevalent and strongly associated with weaning failure, a link between diaphragm weakness and adverse functional outcomes is probable. Mechanisms of critical illness-associated diaphragm weakness are complex and include ventilator-related myotrauma through various pathways (i.e. over-assistance, under-assistance, eccentric, expiratory). Given this potential clinical impact, research on preventive and therapeutic strategies is growing including the development of ventilation strategies aiming at protecting both the lung and the diaphragm. Phrenic nerve stimulation and specific rehabilitation strategies also appear promising.

SUMMARY

Diaphragm dysfunction is associated with adverse clinical outcomes in ventilated patients; therefore, their inspiratory effort and function should be monitored. Whenever possible, and without compromising lung protection, moderate inspiratory effort should be targeted. Phrenic nerve stimulation and specific rehabilitation strategies are promising to prevent and treat diaphragm dysfunction, but further evidence is needed before widespread implementation.

Metabolic cost of physical rehabilitation in mechanically ventilated patients in critical care: an observational study

BACKGROUND

Physical rehabilitation is advocated to improve muscle strength and function after critical illness, yet interventional studies have reported inconsistent benefits. A greater insight into patients' physiological response to exercise may provide an option to prescribe individualised, targeted rehabilitation, yet there is limited data measuring oxygen consumption (VO2) during physical rehabilitation. We aimed to test the feasibility of measuring VO2 during seated and standing exercise using the Beacon Caresystem and quantify within- and between-patient variability of VO2 percentage change.

METHODS

We conducted a prospective observational study on patients mechanically ventilated for ≥72 hours and able to participate in physical rehabilitation in critical care. Oxygen consumption was measured continuously using indirect calorimetry. A total of 29 measurements were taken from ten participants performing active sitting and standing exercise.

RESULTS

Median (IQR) first session baseline VO2 was 3.54 (2.9-3.9) mL/kg/min, increasing significantly to 4.37 (3.96-5.14) mL/kg/min during exercise (p=0.005). The median (IQR) coefficient of variation of VO2 percentage change in participants (n=7) who completed more than one rehabilitation session (range 2-7 sessions) was 43 (34-61)% in 26 measurements. The median (IQR) coefficient of variation of VO2 percentage change was 46 (26-63)% in participants performing >1 sitting exercise session (six participants, 19 sessions).

CONCLUSIONS

VO2 increases significantly with exercise but is highly variable between participants, and in the same participant on separate occasions, performing the same functional activity. These data suggest that simplified measures of function do not necessarily relate to oxygen consumption.

TRIAL REGISTRATION NUMBER

NCT05101850.

Intraoperative phrenic nerve stimulation to prevent diaphragm fiber weakness during thoracic surgery

Thoracic surgery rapidly induces weakness in human diaphragm fibers. The dysfunction is thought to arise from combined effects of the surgical procedures and inactivity. This project tested whether brief bouts of intraoperative hemidiaphragm stimulation would mitigate slow and fast fiber loss of force in the human diaphragm. We reasoned that maintenance of diaphragm activity with brief bouts of intraoperative phrenic stimulation would mitigate diaphragm fiber weakness and myofilament protein derangements caused by thoracic surgery. Nineteen adults (9 females, age 59 ± 12 years) with normal inspiratory strength or spirometry consented to participate. Unilateral phrenic twitch stimulation (twitch duration 1.5 ms, frequency 0.5 Hz, current 2x the motor threshold, max 25 mA) was applied for one minute, every 30 minutes during cardiothoracic surgery. Thirty minutes following the last stimulation bout, biopsies were obtained from the hemidiaphragms for single fiber force mechanics and quantitation of myofilament proteins (abundance and phosphorylation) and compared by a linear mixed model and paired t-test, respectively. Subjects underwent 6 ±  2 hemidiaphragm stimulations at 17 ±  6 mA, during 278 ±  68 minutes of surgery. Longer-duration surgeries were associated with a progressive decline in diaphragm fiber force (p < 0.001). In slow-twitch fibers, phrenic stimulation increased absolute force (+25%, p <  0.0001), cross-sectional area (+16%, p < 0.0001) and specific force (+7%, p < 0.0005). Stimulation did not alter contractile function of fast-twitch fibers, calcium-sensitivity in either fiber type, and abundance and phosphorylation of myofilament proteins. In adults without preoperative weakness or lung dysfunction, unilateral phrenic stimulation mitigated diaphragm slow fiber weakness caused by thoracic surgery, but had no effect on myofilament protein abundance or phosphorylation.

Diaphragmatic ultrasound: approach, emerging evidence, and future perspectives in non-ICU patients

Diaphragmatic dysfunction is an important contributor to hypercapnic respiratory failure, but its presence is often challenging to determine at the bedside. Diaphragm ultrasound provides an opportunity to evaluate the function of the diaphragm noninvasively by evaluating the following parameters that can help define diaphragmatic dysfunction: diaphragm excursion, diaphragm muscle thickness, and thickening fraction. Its evaluation has the potential to assist with diagnosis of respiratory failure, provide prognosis, and assist with patient monitoring and should be considered as part of an internal medicine physician's and emergency physician's skill set. This article provides an overview on how to perform diaphragm ultrasound, review its pitfalls, and discuss the evidence of its use in patients with neuromuscular disorders and chronic obstructive pulmonary disease. Finally, its potential emerging uses in the perioperative setting and for evaluation of acute heart failure are discussed.

A Study on the Diagnostic Accuracy of Tidal Volume-Diaphragmatic Contraction Velocity: A Novel Index for Weaning Outcome Prediction

OBJECTIVES

Weaning failure from mechanical ventilation (MV) is primarily caused by increased respiratory load and decreased respiratory neuromuscular competency, leading to a rapid shallow breathing pattern. We hypothesized that the product of diaphragmatic contraction velocity (a sonographic estimate of respiratory load) and tidal volume (an estimate of breathing pattern), termed the volume-velocity index (VVI), may predict weaning outcomes.

DESIGN

The diagnostic accuracy of VVI (mL*cm/s) in predicting weaning outcomes was prospectively assessed, along with its relationship to indices of breathing effort, including esophageal pressure swings (ΔPes), the pressure-time product of esophageal pressure (PTPes), and maximal inspiratory pressure (MIP). A power analysis, informed by the results of an inception cohort, determined the required sample size for the validation cohort. Patients were enrolled through consecutive sampling. Weaning failure was defined as failure of the spontaneous breathing trial (SBT) or the need for MV within 48 hours.

SETTING

The study was conducted in a tertiary academic ICU.

PATIENTS

VVI was evaluated in critical care patients undergoing a SBT for the first time.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In the inception cohort (n = 30), VVI was significantly higher in successful weaning compared to failures (764.76 [±432.61] vs. 278 [±183.66], p < 0.001). It correlated with ΔPes (r = 0.74, R2 = 0.55), PTPes (r = 0.76, R2 = 0.58), and MIP (r = 0.75, R2 = 0.55) all p values less than 0.001. In the validation cohort (n = 40), VVI was higher in successful weaning (840 [550, 1220] vs. 250 [225, 302.5], p < 0.001) and predicted weaning success with an area under the receiver operating characteristic of 0.92 (95% CI, 0.83-1).

CONCLUSIONS

VVI effectively differentiates between weaning success and failure, shows a strong correlation with respiratory effort indices, and may enhance weaning protocols.

Respiratory and limb muscles' ability to repeatedly generate maximal isometric strength in patients with intensive care unit-acquired weakness: an observational study

BACKGROUND

Intensive care unit-acquired weakness (ICU-Aw) is a prevalent complication in critically ill patients, affecting both limb and respiratory muscles, individually or concurrently. The precise mechanisms by which muscle weakness influences the distinct functional roles of each muscle group remain to be fully elucidated. The objective of this study was to compare the time course evolution of inspiratory and quadriceps muscles strength during repeated maximal isometric contractions in patients with limb muscles and inspiratory muscles weakness.

METHODS

A single-center, observational study was conducted in critically ill patients after extubation, presenting with both inspiratory and limb muscle weakness (defined as maximal inspiratory pressure (Pimax) < 30 cmH2O and an MRC score < 48). The patients' ability to sustain maximal voluntary effort was measured using electronic manometers and dynamometers, with repeated efforts performed 10 times. Following each measurement, a 10-second rest period was observed, and strength measurements were repeated to evaluate recovery.

RESULTS

A total of 20 patients (90% male, mean age 61 ± 10 years, SAPS II score 28 ± 17) were included. The mean first maximal inspiratory pressure was 32.6 ± 17 cmH2O, and the mean first quadriceps maximal force was 135 ± 90 Newtons (N). Investigation revealed a decline in quadriceps muscle force of -15.45 ± 28.61 N (95% CI: -28.84 to -2.05) while inspiratory muscles demonstrated stability (mean difference: 1.75 ± 7.57 cmH2O (95% CI: -1.80 to 5.30)). A statistically significant interaction between time and muscle group was identified (p = 0.0017), suggesting a different time course evolution of maximal voluntary strength between muscle groups. After a one-minute recovery, significant improvement in quadriceps strength was observed (p = 0.009), while no statistically significant change was detected in inspiratory muscle strength (p = 0.16).

CONCLUSIONS

The results of this study indicate potential disparities in the maximum force maintenance capacity between the quadriceps muscles and inspiratory muscles in patients with ICU-acquired weakness.

TRIAL REGISTRATION

Registered on ClinicalTrials.gov Identifier NCT05396066.

Similar Weaning Success Rate with High-Intensity and Sham Inspiratory Muscle Training: A Randomized Controlled Trial (IMweanT)

Rationale: Inspiratory muscle training (IMT) improves respiratory muscle function in patients with weaning difficulties. IMT protocols involve performing daily sets of breaths against external loads. However, the impact of IMT on weaning outcomes while incorporating sham control interventions remains unclear. Objectives: To compare the effects of a high-intensity IMT (Hi-IMT) intervention with a sham low-intensity (Lo-IMT) control group on weaning outcomes and respiratory muscle and pulmonary function 28 days after inclusion in patients with weaning difficulties. Methods: Both groups underwent daily IMT sessions until successful weaning or a maximum of 28 days. The Hi-IMT group (n = 44; 61% male; aged 57 ± 15 yr) performed maximal inspirations initiated from residual volume against an external load representing 30-50% of maximal inspiratory pressure (PImax), and the control group (n = 46; 52% male; aged 60 ± 12 yr) performed maximal inspirations against a load ⩽10% PImax. Measurements and Main Results: Training adherence (completed/planned sessions) was comparable between the groups (Hi-IMT, 77 ± 20%; Lo-IMT, 72 ± 17%; P = 0.25). Weaning success (64% Hi-IMT and 76% Lo-IMT; P = 0.43) and weaning duration (Hi-IMT, 45 ± 48 d; Lo-IMT, 37 ± 26 d; P = 0.33) were similar between groups. Both groups similarly improved PImax (Hi-IMT, +15 cm H2O [95% confidence interval (CI), 9, 20]; Lo-IMT, +14 cm H2O [95% CI, 9, 19]; P = 0.72). FVC improved more in the Hi-IMT group than in the Lo-IMT group (Hi-IMT, +0.33 L [95% CI, 0.22, 0.43]; Lo-IMT, +0.16 L [95% CI, 0.07, 0.25]; P = 0.04). Conclusions: Both high-intensity IMT and sham low-intensity IMT, with high adherence to the protocol, resulted in similar weaning success rates and pronounced improvements in maximal inspiratory muscle strength. Clinical trial registered with www.clinicaltrials.gov (NCT03240263).

Establishment of a prediction model for extubation failure risk in ICU patients using bedside ultrasound technology

BACKGROUND

Mechanical ventilation (MV) is crucial for managing critically ill patients; however, extubation failure, associated with adverse outcomes, continues to pose a significant challenge.

OBJECTIVE

The purpose of this prospective observational study was to develop and validate a predictive numerical model utilizing bedside ultrasound to forecast extubation outcomes in ICU patients.

METHODS

We enrolled 300 patients undergoing MV, from whom clinical variables, biomarkers, and ultrasound parameters were collected. Patients were randomly assigned to two groups at a 6:4 ratio: the derivation cohort (n = 180) and the validation cohort (n = 120). A nomogram prediction model was developed using significant predictors identified through multivariate analysis and its performance was assessed and validated by evaluating its discrimination, calibration, and clinical utility.

RESULTS

A total of 300 patients (mean age 72 years; 57.3 % male) were included, with an extubation failure rate of 26.7 %. The model, including diaphragm thickening fraction (OR: 0.890, P = 0.009), modified lung ultrasound score (OR: 1.371, P < 0.001), peak relaxation velocity (OR: 1.515, P = 0.015), and APACHE II (OR: 1.181, P = 0.006), demonstrated substantial discriminative capability, as indicated by an area under the receiver operating characteristic curve (AUC) of 0.886 (95 % CI: 0.830-0.942) for the derivation cohort and 0.846 (95 % CI: 0.827-0.945) for the validation cohort. Hosmer-Lemeshow tests yielded P-values of 0.224 and 0.212 for the derivation and validation cohorts.

CONCLUSIONS

We have established a risk prediction model for extubation failure in mechanically ventilated ICU patients. This risk model base on bedside ultrasound parameters provides valuable insights for identifying high-risk patients and preventing extubation failure.

Ultrasound-guided Transcutaneous Phrenic Nerve Stimulation in Critically Ill Patients: A New Method to Evaluate Diaphragmatic Function

BACKGROUND

Diaphragm dysfunction is common in intensive care unit and associated with weaning failure and mortality. The diagnosis gold standard is the transdiaphragmatic or tracheal pressure induced by magnetic phrenic nerve stimulation. However, the equipment is not commonly available and requires specific technical skills. This study aimed to evaluate ultrasound-guided transcutaneous phrenic nerve stimulation for daily bedside assessment of diaphragm function by targeted electrical phrenic nerve stimulation.

METHODS

This randomized crossover study compared a new method of ultrasound-guided transcutaneous electrical phrenic nerve stimulation (SONOTEPS) using a peripheral nerve stimulator, with magnetic phrenic nerve stimulation. Intensive care unit adult patients under mechanical ventilation with a Richmond Agitation-Sedation Scale score of -4 or -5 were included. Each patient received the two methods of stimulation, in a randomized order. The primary outcome was the tracheal pressure induced by stimulation.

RESULTS

This study analyzed 232 measures of tracheal pressure from 116 patients, of whom 77 presented diaphragm dysfunction (tracheal pressure less than 11 cm H 2 O) and 50 presented severe diaphragm dysfunction (tracheal pressure less than 8 cm H 2 O). The Passing-Bablok regression showed no significant differences (intercept A of -0.03 [95% CI, -0.83 to 0.52] and slope B of 0.98 [95% CI, 0.90 to 1.05]) between the SONOTEPS method and magnetic stimulation, which were positively correlated ( R ² = 0.639). The mean bias was -1.08 (95% CI, 5.02 to -7.18) cm H 2 O. The receiver operating curves showed an excellent performance for the diagnosis of diaphragm dysfunction and severe diaphragm dysfunction with areas under the curve of 0.90 (95% CI, 0.83 to 0.97) and 0.88 (95% CI, 0.82 to 0.95), respectively. This performance was not significantly affected by the body mass index or the presence of a neck catheter.

CONCLUSIONS

The SONOTEPS method is a simple and accurate tool for bedside assessment of diaphragm function with ultrasound-guided transcutaneous phrenic nerve stimulation in sedated patients with no or minimal spontaneous respiratory activity.

The modified effect of mechanical ventilation setting on relationship between fluid balance and hospital mortality for sepsis patients: a retrospective study

BACKGROUND

Fluid supplement may be affected by ventilatory management due to physiological interaction between heart and lung. The aim of the present study was to explore the effects of ventilator strategies on the relationship of fluid balance and hospital mortality for sepsis patients.

METHODS

This was a retrospective cohort study included sepsis patients with invasive mechanical ventilation (MV) over 24 h from Medical Information Mart for Intensive Care (MIMIC) IV database. The accumulative fluid balance increased by 6 h intervals were calculated as fluid intake minus fluid output. The modes (assisted or controlled) and levels (high or low) of positive end-expiratory pressure (PEEP) of MV every 6 h were recorded. The modification effect for modes and levels of PEEP on the relationship of fluid balance and hospital mortality were tested by multivariable regression models, respectively.

RESULTS

A total of 4466 sepsis patients with invasive MV were included, of which hospital mortality was 26.5%. Fluid balance seemed to have U-shape relationship with hospital mortality. The majority of patients used controlled ventilation at the beginning, and switched to assisted ventilation gradually; however, the PEEP level did not change a lot during the first 24 h. The relationship between fluid balance and hospital mortality was not modified by the ventilator mode; while the PEEP level may modify the relationship.

CONCLUSIONS

For sepsis patients admitted to ICU with invasive MV, the PEEP level, but not the mode of MV, appeared to modify the relationship of fluid balance and hospital mortality. The setting of mechanical ventilation may be an important consideration for fluid therapy.

Weakness acquired in the cardiac intensive care unit: still the elephant in the room?

Over the past two decades, the cardiac critical care population has shifted to increasingly comorbid and elderly patients often presenting with nonprimary cardiac conditions that exacerbate underlying advanced cardiac disease. Consequently, the modern cardiac intensive care unit (CICU) patient has poor outcome regardless of left ventricular ejection fraction. Importantly, delayed liberation from organ support, independent from premorbid health status and admission severity of illness, has been associated with increased morbidity and mortality up to years post-general critical care. Although a constellation of several acquired morbidities is at play, the most prominent enactor of poor long-term outcome in this population appears to be intensive care unit acquired weakness. Although the specific burden of ICU-acquired morbidities in CICU patients is yet to be clearly defined, it seems unfathomable that patients will not accrue some sort of ICU-related morbidity. There is hence an urgent need to better establish the exact benefit and cost of resource-intensive strategies in both short- and long-term survival of the CICU patient. Consequent and standardized documentation of admission comorbidities, severity of illness indicators, relevant ICU-related complications including weakness, and long-term post-ICU morbidity outcomes can help our understanding of the disease continuum and how to better care for the CICU survivor and their families and caregivers. Given increasing budgetary pressure on healthcare systems worldwide, interventions targeting CICU patients should focus on improving patient-centred long-term outcomes in a cost-effective manner. It will require a holistic and transmural continuity of care model to meet the challenges associated with treating critically ill cardiac patients in the future.

Within- and between-day test-retest reliability of responses to rapid bilateral anterolateral magnetic phrenic nerve stimulation in healthy humans (ReStim)

Background

Mechanical ventilation can lead to lung injury and diaphragmatic dysfunction. Rapid bilateral anterolateral magnetic phrenic nerve stimulation (rBAMPS) may attenuate both of the aforementioned issues by inducing diaphragm activation. However, in order for rBAMPS to become part of standard of care, the reliability of inspiratory responses to rBAMPS needs to be established.

Methods

Eighteen healthy participants (9F) underwent five blocks of 1-s rBAMPS at 25 Hz starting at 20% of maximal stimulator output with 10% increments. Three blocks were completed on the same day to test within-day reliability, and two additional blocks were each completed on subsequent days to test between-day reliability. Mean transdiaphragmatic pressure (Pdi,mean), tidal volume (VT), discomfort, pain, and paresthesia were recorded for each rBAMPS. Relative and absolute reliability of both Pdi,mean and VT were quantified by calculating intraclass correlation coefficients (ICC) and standard error of measurements (SEM), respectively. An ordinal regression was used to determine changes of sensory ratings within and between days.

Results

At all stimulator outputs, within-day Pdi,mean displayed "good" reliability (ICC range 0.78-0.89). Between days, Pdi,mean reliability was also "good" (ICC range 0.79-0.87) at stimulator outputs of 20%-50% of maximum, but "moderate" (ICC range 0.56-0.72) at stimulator outputs of 60%-100%. SEM for Pdi,mean within day ranged from 0.9 to 3.4 across tested stimulator outputs and increased on average by 1.4 ± 0.9 between days. The VT reliability was "good" to "excellent" within (ICC range 0.82-0.94) and between (ICC range 0.81-0.96) days at all stimulator outputs. SEM for VT within day ranged from 0.08 to 0.36 and from 0.11 to 0.30 between days and tended to be larger at stimulator outputs greater than 50% of maximum. Subsequent blocks within day were associated with decreased discomfort and pain (P ≤ 0.043), while subsequent days were associated with decreased discomfort and paresthesia (P < 0.001).

Discussion

rBAMPS appears to induce reliable diaphragmatic contractions, while select sensory responses become blunted over repeated stimulations. However, as reliability is slightly lower between days compared to within day, stimulation parameters may need to be adjusted to achieve similar responses on different days.

Intensive care unit acquired weakness and physical rehabilitation in the ICU

Approximately half of critically ill adults experience intensive care unit acquired weakness (ICUAW). Patients who develop ICUAW may have negative outcomes, including longer duration of mechanical ventilation, greater length of stay, and worse mobility, physical functioning, quality of life, and mortality. Early physical rehabilitation interventions have potential for improving ICUAW; however, randomized trials show inconsistent findings on the efficacy of these interventions. This review summarizes the latest evidence on the definition, diagnosis, epidemiology, pathophysiology, risks factors, implications, and management of ICUAW. It specifically highlights research gaps and challenges, with considerations for future research for physical rehabilitation interventions.

Ultrasound-based abdominal muscles and diaphragm assessment in predicting extubation failure in patients requiring neurointensive care: a single-center observational study

Extubation failure rates are notably high in patients in neurointensive care. Ineffective cough is the variable independently associated with extubation failure, but its quantification remains challenging. Patients with primary central nervous system injury requiring invasive mechanical ventilation were included. After a successful spontaneous breathing trial (SBT), abdominal muscles and diaphragm ultrasound were performed under tidal breathing and coughing. 98 patients were initially recruited for the study, and 40 patients were ultimately included in the final analysis. Extubation failure occurred in 8 (20%) patients. Rectus abdominis (RA) and internal oblique (IO) muscles showed difference regarding cough thickening fraction (TF) between the extubation success and failure group (P < 0.05). The logistic regression that analysis suggested cough TFRA, cough TFIO and cough TIO were the factors associated with extubation outcome (P < 0.05). In the receiver operating characteristic analysis, cough TFIO exhibited the strongest predictive value (AUC = 0.957, 95% CI:0.8979-1). A threshold of cough TFIO ≥ 34.15% predicted extubation success with a sensitivity of 93.8% and specificity of 75%. Abdominal muscles ultrasound was a promising tool to predict extubation for patients requiring neurointensive care.Trial registration: The study was registered on Chinese Clinical Trial Registry: ChiCTR2400088210, Registered 13 August 2024 - Retrospectively registered, https://www.chictr.org.cn/bin/project/edit?pid=234150 .

USE OF MUSCULAR ULTRASOUND TO DETECT INTENSIVE CARE UNIT-ACQUIRED WEAKNESS: A SYSTEMATIC REVIEW AND META-ANALYSIS

ABSTRACT

Background : This systematic review and meta-analysis aims to detecting performance of muscular ultrasound for intensive care unit (ICU)-acquired weakness (ICUAW). Methods : We searched PubMed, Web of Science, Embase, Cochrane library, CNKI, VIP, and Wanfang databases for articles published before July 2024. A random-effects model was utilized to derive the summary estimates of sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence interval (CI). Additionally, the sources of heterogeneity were explored by subgroup analysis and meta-regression. Results : This meta-analysis comprised 10 prospective studies involving 561 participants, of whom 241 (42.96%) were diagnosed as ICUAW. Overall, muscular ultrasound exhibited good performance for detecting ICUAW, with the area of summary receiver operating characteristic (SROC) curve of 0.85 (95%CI 0.82-0.88), sensitivity of 0.76 (95%CI 0.70-0.81), specificity of 0.80 (95%CI 0.74-0.84), and DOR of 12.43 (95%CI 7.98-19.38). Upon predefined subgroup analysis, the rectus femoris exhibited significantly superior discriminatory ability in identifying ICUAW than the non-rectus femoris, with higher SROC (0.88 [95%CI 0.85-0.91] vs. 0.76 [95%CI 0.72-0.79], P < 0.01). Moreover, cross-sectional area was more effective than thickness, with higher specificity (0.86 [95%CI 0.80-0.91] vs. 0.74 [95%CI 0.68-0.79], P = 0.02) and SROC (0.89 [95%CI 0.86-0.92] vs. 0.76 [95%CI 0.72-0.80], P < 0.01). Furthermore, integrated analysis of these two indicators revealed that the cross-sectional area of rectus femoris was statistically superior to the thickness of rectus femoris, with higher sensitivity (0.82 [95%CI 0.74-0.87] vs. 0.75 [95%CI 0.65-0.83], P < 0.05) and AUC (0.91 [95%CI 0.88-0.93] vs. 0.80 [95%CI 0.76-0.83], P < 0.01). Conclusions : Muscular ultrasound could be a reliable tool for ICUAW detection. Compared with alternative indices, the cross-sectional area of the rectus femoris exhibits superior detection efficacy and may be considered as a valuable parameter for clinical application.

Effectiveness of physiotherapy modalities on persisting dyspnoea in long COVID: A systematic review and meta-analysis

BACKGROUND

Dyspnoea is often found months and years later in the "long-covid" syndrome, impairing quality of life and further perpetuating anxiety and post-traumatic stress disorders. Physiotherapy was recommended as a treatment in long-covid, but there is still insufficient evidence on its effectiveness.

METHODS

We conducted a systematic literature search on MEDLINE, PEDro, WOS, Scopus, VHL and the Cochrane Library until July 2023 (PROSPERO registration number: CRD42023427464). We selected comparative trials including adults with persistent breathlessness following COVID-19, regardless of the initial severity, for whom physiotherapy was implemented as a treatment for dyspnoea. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and assessed the study quality using the PEDro Scale.

RESULTS

19 studies that included 1292 adults fulfilled the inclusion criteria, of which 15 were randomised controlled trials and 4 non-randomised controlled trials. As for the rehabilitation modalities, 6 studies used respiratory muscle training, 6 studies used low to moderate intensity rehabilitation, 6 used high intensity rehabilitation and one used passive rehabilitation. The methods used between and within each group differed greatly, leading to an expected high heterogeneity of results. Nethertheless the random-effects model found a significant difference favouring physiotherapy (SMD -0.63, 95 CI [-1.03; -0.24], p < 0.001, I2 = 88 %). Subgroup analysis showed a significant effect in the high intensity rehabilitation group alone, with null heterogeneity.

CONCLUSION

In people suffering from dyspnoea following a SARS-CoV-2 infection, physiotherapy and especially pulmonary rehabilitation may help alleviate respiratory symptoms. Future studies will need to provide more consistent rehabilitation methods and better descriptions of them so as to reveal clear effects and avoid the confusion caused by using too many rehabilitation modalities.

Diaphragm dysfunction: how to diagnose and how to treat?

The diaphragm, crucial for respiratory function, is susceptible to dysfunction due to various pathologies that can affect the nervous system, neuromuscular junction or the muscle itself. Diaphragmatic dysfunction presents with symptoms ranging from exertional dyspnoea to respiratory failure, significantly impacting patients' quality of life. Diagnosis involves clinical evaluation complemented by imaging and pulmonary function tests. Chest radiography, fluoroscopy, and ultrasonography are pivotal in assessing diaphragmatic movement and excursion, offering varying sensitivities and specificities based on the type and severity of dysfunction. Ultrasonography emerges as a noninvasive bedside tool with high sensitivity and specificity, measuring diaphragm thickness, thickening fraction, and excursion, and enabling monitoring of disease progression and response to treatment over time. Treatment strategies depend on the underlying aetiology and severity, ranging from conservative management to interventions such as surgical plication or diaphragmatic pacing. Ventilatory support, particularly noninvasive ventilation, plays a pivotal role in treatment, enhancing lung function and patient outcomes across unilateral and bilateral dysfunction. Despite advances in diagnostic techniques, awareness and systematic evaluation of diaphragmatic function remain inconsistent across clinical settings. This review consolidates the current understanding of diaphragmatic dysfunction, highlighting diagnostic modalities and treatment options to facilitate early recognition and management of this entity.

Contribution and evolution of respiratory muscles function in weaning outcome of ventilator-dependent patients

BACKGROUND

The present study was designed to investigate the evolution and the impact of respiratory muscles function and limb muscles strength on weaning success in prolonged weaning of tracheotomized patients. The primary objective was to determine whether the change in respiratory muscles function and limb muscles strength over the time is or is not associated with weaning success.

METHODS

Tracheotomized patients who were ventilator dependent upon admission at a weaning center were eligible. Diaphragm function was assessed with the phrenic nerve stimulation technique and with ultrasound to measure the diaphragm thickening fraction (TFdi) and diaphragm excursion (EXdi). Global respiratory muscle function was assessed with the maximal inspiratory pressure (MIP) and the forced vital capacity (FVC). Limb muscle strength was measured with the Medical Research Council Score (MRC). Measurements were made on a weekly basis. Patients were compared according to their outcome at discharge: complete weaning, partial weaning or death.

RESULTS

Among the 60 patients who were enrolled, 30 patients finally achieved complete weaning, 20 had partial weaning and 10 died. At 6 months, 6 patients were lost of follow-up, 33 achieved complete weaning, 10 had partial weaning and 11 died. In median, 2 (1-9) assessments were performed per patient. Diaphragm dysfunction was present in all patients with a median Ptr,stim of 5.5 cmH2O (3.0-7.5). Ptr,stim, MIP, TFdi and EXdi at admission were not different between patients who achieved complete weaning and their counterparts. At discharge of the weaning center, MIP, Ptr,stim and EXdi significantly increased in patients who achieved complete weaning. The MRC score significantly increased only in patients with complete weaning. At discharge, diaphragm dysfunction was highly prevalent even in patients with complete weaning (Ptr,stim < 11 cmH2O in n = 11 (37%)).

CONCLUSION

Respiratory muscle function and limb muscles strength are severely impaired in patients with prolonged weaning from mechanical ventilation. Significant improvement of diaphragm ultrasound indices was associated with successful weaning from mechanical ventilation and ICU-acquired weakness upon admission was significantly associated with good outcome suggesting that it was an amendable determinant of weaning failure in this population.

Speckle tracking ultrasound as a new tool to predict the weaning outcome of mechanical ventilation patients: a prospective observational study

Introduction

Speckle tracking ultrasound is a novel technique for evaluating diaphragm movement, yet its guidance in weaning mechanically ventilated patients remains unclear. In this study, we assessed diaphragmatic function using speckle tracking ultrasound and guided the weaning process.

Methods

A total of 86 mechanically ventilated patients were included and divided into successful or failed weaning groups. Diaphragmatic function was assessed using speckle tracking ultrasound, M-ultrasound diaphragm excursion (DE), and diaphragmatic twitch force (DTF) after 30 min spontaneous breathing trial (SBT). The diagnostic performance of these indicator in predicting weaning outcomes was also evaluated.

Results

In this study, a total of 86 patients completed the follow-up for weaning outcomes, with 35 cases of weaning failure and 51 cases of successful weaning. Logistic regression analysis identified whole strain (p = 0.037) and DE (p = 0.004) as independent predictors of weaning outcome. Receiver operating characteristic (ROC) curve showed that the strain threshold for Costal Diaphragm (Dlcos) was -9.836, Area Under the Curve (AUC) value was 0.760, the predictive specificity for weaning failure was 72.5%, and the sensitivity was 80%. DE value exceeding 1.015 cm had an AUC value of 0.785, noting that DE value had a high specificity (90.2%) for predicting successful weaning, but a lower sensitivity (60%). After merging, the AUC of whole strain and DE was 0.856, and the sensitivity (80%) and specificity (80.4%) were more balanced compared to using DE alone.

Conclusion

The findings of this study demonstrate the feasibility of using speckle tracking ultrasound to assess diaphragmatic function in mechanically ventilated patients. The combined utilization of whole strain and DE provides a more precise evaluation of diaphragmatic function in ICU patient, which may improve patient outcome.

Rehabilitation effects of acupuncture on the diaphragmatic dysfunction in respiratory insufficiency: A systematic review and meta-analysis

INTRODUCTION

Mechanical ventilation after respiratory insufficiency can induce diaphragm dysfunction through various hypothesized mechanisms. In this study, we evaluated the rehabilitative effect of acupuncture on diaphragm function in patients with respiratory insufficiency using meta-analysis and summarised the rules of acupoints through association rules analysis.

METHODS

Articles (published from January 2000 to February 2024) were retrieved from the following databases: PubMed, Cochrane Library, Embase, Web of Science, CNKI, VIP, SinoMed, and Wanfang. Two researchers conducted literature selection, data extraction, and statistical analysis independently. The risk of bias was assessed utilizing the Physical Therapy Evidence Database (PEDro) scale. The meta-analysis was performed with RevMan 5.4 software, and the quality of each outcome evidence was assessed via the online software GRADEpro GDT. The regularity of acupoint selection was summarized using association rules analysis. This study is registered on PROSPERO, number CRD42024526705.

RESULTS

Eleven articles were eventually included, all of which were of low to moderate quality. Results of the meta-analysis showed a significant increase in diaphragmatic thickening fraction (MD 3.40 [1.52, 5.27]) and diaphragmatic excursion (MD 0.95 [0.58, 1.31]) in patients with respiratory insufficiency after acupuncture treatment. Also, OI (MD 28.52 [15.93, 41.11]) and PaO2 (MD 7.18 [2.22, 12.13]) were significantly elevated and PaCO2 (MD -6.94 [-12.30, -1.59]) was decreased. Mechanical ventilation time (MD-1.86 [-2.28, -1.45]) was also significantly improved. The overall quality of the outcome evidence is deemed moderate. Association rules analysis showed that ST36, RN4, RN6, and others are core acupoints for the treatment of diaphragmatic dysfunction in patients with respiratory insufficiency by acupuncture.

CONCLUSION

Acupuncture shows potential in the rehabilitation of patients with respiratory insufficiency and may serve as a complementary and alternative therapy for related conditions. We suggest the use of ST36 as a core acupoint, in combination with other acupoints. Due to the potential publication bias and high heterogeneity of the current data, further high-quality RCTs are needed to confirm these findings.

Lung and Diaphragm Protection During Mechanical Ventilation in Patients with Acute Respiratory Distress Syndrome

Patients with acute respiratory distress syndrome often require mechanical ventilation to maintain adequate gas exchange and to reduce the workload of the respiratory muscles. Although lifesaving, positive pressure mechanical ventilation can potentially injure the lungs and diaphragm, further worsening patient outcomes. While the effect of mechanical ventilation on the risk of developing lung injury is widely appreciated, its potentially deleterious effects on the diaphragm have only recently come to be considered by the broader intensive care unit community. Importantly, both ventilator-induced lung injury and ventilator-induced diaphragm dysfunction are associated with worse patient-centered outcomes.

The Application of Diaphragm Ultrasound in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic Obstructive Pulmonary Disease (COPD) is a prevalent condition that poses a significant burden on individuals and society due to its high morbidity and mortality rates. The diaphragm is the main respiratory muscle, its function has a direct impact on the quality of life and prognosis of COPD patients. This article aims to review the structural measurement and functional evaluation methods through the use of diaphragmatic ultrasound and relevant research on its application in clinical practice for COPD patients. Thus, it serves to provide valuable insights for clinical monitoring of diaphragm function in COPD patients, facilitating early clinical intervention and aiding in the recovery of diaphragm function.

Inspiratory muscle training for mechanically ventilated patients in the intensive care unit: Obstacles and facilitators for implementation. A mixed method quality improvement study

BACKGROUND

Mechanically ventilated patients are at risk of developing inspiratory muscle weakness (IMW), which is associated with failure to wean and poor outcomes. Inspiratory muscle training (IMT) is a recommended intervention during and after extubation but has not been widely adopted in Dutch intensive care units (ICUs).

OBJECTIVES

The objective of this study was to explore the potential, barriers, and facilitators for implementing IMT as treatment modality for mechanically ventilated patients.

METHODS

This mixed-method, proof-of-concept study was conducted in a large academic hospital in the Netherlands. An evidence-based protocol for assessing IMW and training was applied to patients ventilated for ≥24 h in the ICU during an 8-month period in 2021. Quantitative data on completed measurements and interventions during and after ICU-stay were collected retrospectively and were analysed descriptively. Qualitative data were collected through semistructured interviews with physiotherapists executing the new protocol. Interview data were transcribed and thematically analysed.

FINDINGS

Of the 301 screened patients, 11.6% (n = 35) met the inclusion criteria. Measurements were possible in 94.3% of the participants, and IMW was found in 78.8% of the participants. Ninety-six percent started training in the ICU, and 88.5% continued training after transfer to the ward. Follow-up measurements were achieved in 73.1% of the patients with respiratory muscle weakness. Twelve therapists were interviewed, of whom 41.7% regularly worked in the ICU. When exploring reasons for protocol deviation, three themes emerged: "professional barriers", "external factors", and "patient barriers".

CONCLUSIONS

Implementation of measurements of and interventions for IMW showed to be challenging in this single centre study. Clinicians' willingness to change their handling was related to beliefs regarding usefulness, effectiveness, and availability of time and material. We recommend that hospitals aiming to implement IMT during or after ventilator weaning consider these professional and organisational barriers for implementation of novel, evidence-based interventions into daily clinical practice.

Impact of COVID-19 on Diaphragmatic Function: Understanding Multiorgan Involvement and Long-Term Consequences

The COVID-19 pandemic has brought significant attention to the respiratory system, with much focus on lung-related disorders. However, the diaphragm, a crucial component of respiratory physiology, has not been adequately studied, especially in the context of long COVID. This review explores the multipotential role of the diaphragm in both respiratory health and disease, emphasizing its involvement in long-term complications following SARS-CoV-2 infection. The diaphragm's fundamental role in respiratory physiology and its impact on balance and posture control, breathing patterns, and autonomic nervous system regulation are discussed. This review examines complications arising from COVID-19, highlighting the diaphragm's involvement in neurological, musculoskeletal, and inflammatory responses. Particular attention is given to the neuroinvasive impact of SARS-CoV-2, the inflammatory response, and the direct viral effects on the diaphragm. The diaphragm's role in long COVID is explored, with a focus on specific symptoms such as voice disorders, pelvic floor dysfunction, and sleep disturbances. Diagnostic challenges, current methods for assessing diaphragmatic dysfunction, and the complexities of differentiating it from other conditions are also explored. This article is the first to comprehensively address diaphragmatic dysfunction resulting from COVID-19 and long COVID across various physiological and pathological aspects, offering a new perspective on its diagnosis and treatment within a multisystem context.

Effectiveness of abdominal sandbag training in enhancing diaphragm muscle function and exercise tolerance in patients with chronic respiratory failure

BACKGROUND

Chronic respiratory failure is a common cause of ventilator dependence in the intensive care unit (ICU). The causes of chronic respiratory failure include primary disease or complications, such as ICU-acquired weakness. Traditional practice requires patients to remain immobile and bedridden; however, recent evidence suggests that early adequate exercise promotes recovery without increasing risks. In this study, we explored the efficacy of planned progressive abdominal sandbag training in promoting the successful withdrawal of patients with chronic respiratory failure from mechanical ventilation.

METHODS

This study was conducted between April 2019 and November 2020. Patients were recruited and divided into two groups: abdominal sandbag training group and control group (no training). The training group participated in a 3-month daily pulmonary rehabilitation program, which involved a 30-min session of progressive sandbag loading on the upper abdomen as a form of diaphragmatic resistant exercise. The pressure support level of the ventilator was adjusted to maintain a tidal volume of 8 mL/kg. To investigate the effect of abdominal sandbag training on patients with chronic respiratory failure, we compared tidal volume, shallow breathing index, maximum respiratory pressure, and diaphragm characteristics between the training and control groups.

RESULTS

This study included 31 patients; of them, 17 (54.8 %) received abdominal sandbag training and 14 (45.2 %) did not. No significant between-group difference was found in baseline characteristics. Compared with the control group, the training group exhibited considerable improvements in ventilation-related parameters (p < 0.001): the tidal volume markedly increased (p = 0.012), rapid shallow breathing index declined (p = 0.016), and maximum respiratory pressure increased (p < 0.001) in the training group. The diaphragm motion value (p = 0.048) and diaphragm thickness (p = 0.041) were greater in the training group than in the control group. Nine patients (52.9 %) in the training group were removed from the ventilator compared with 1 (7.1 %) in the control group (p = 0.008).

CONCLUSION

Abdominal sandbag training may be beneficial for patients dependent on a ventilator. The training improves the function of the diaphragm muscle, thereby increasing tidal volume and reducing the respiratory rate and rapid shallow breathing index, thus facilitating withdrawal from ventilation. This training approach may also improve the thickness and motion of the diaphragm and the rate of ventilator detachment.

Pressure control plus spontaneous ventilation versus volume assist-control ventilation in acute respiratory distress syndrome. A randomised clinical trial

PURPOSE

The aim of this study was to compare the effect of a pressure-controlled strategy allowing non-synchronised unassisted spontaneous ventilation (PC-SV) to a conventional volume assist-control strategy (ACV) on the outcome of patients with acute respiratory distress syndrome (ARDS).

METHODS

Open-label randomised clinical trial in 22 intensive care units (ICU) in France. Seven hundred adults with moderate or severe ARDS (PaO2/FiO2 < 200 mmHg) were enrolled from February 2013 to October 2018. Patients were randomly assigned to PC-SV (n = 348) or ACV (n = 352) with similar objectives of tidal volume (6 mL/kg predicted body weight) and positive end-expiratory pressure (PEEP). Paralysis was stopped after 24 h and sedation adapted to favour patients' spontaneous ventilation. The primary endpoint was in-hospital death from any cause at day 60.

RESULTS

Hospital mortality [34.6% vs 33.5%, p = 0.77, risk ratio (RR) = 1.03 (95% confidence interval [CI] 0.84-1.27)], 28-day mortality, as well as the number of ventilator-free days and organ failure-free days at day 28 did not differ between PC-SV and ACV groups. Patients in the PC-SV group received significantly less sedation and neuro-muscular blocking agents than in the ACV group. A lower proportion of patients required adjunctive therapy of hypoxemia (including prone positioning) in the PC-SV group than in the ACV group [33.1% vs 41.3%, p = 0.03, RR = 0.80 (95% CI 0.66-0.98)]. The incidences of pneumothorax and refractory hypoxemia did not differ between the groups.

CONCLUSIONS

A strategy based on PC-SV mode that favours spontaneous ventilation reduced the need for sedation and adjunctive therapies of hypoxemia but did not significantly reduce mortality compared to ACV with similar tidal volume and PEEP levels.

Respiratory muscle dysfunction in acute and chronic respiratory failure: how to diagnose and how to treat?

Assessing and treating respiratory muscle dysfunction is crucial for patients with both acute and chronic respiratory failure. Respiratory muscle dysfunction can contribute to the onset of respiratory failure and may also worsen due to interventions aimed at treatment. Evaluating respiratory muscle function is particularly valuable for diagnosing, phenotyping and assessing treatment efficacy in these patients. This review outlines established methods, such as measuring respiratory pressures, and explores novel techniques, including respiratory muscle neurophysiology assessments using electromyography and imaging with ultrasound.Additionally, we review various treatment strategies designed to support and alleviate the burden on overworked respiratory muscles or to enhance their capacity through training interventions. These strategies range from invasive and noninvasive mechanical ventilation approaches to specialised respiratory muscle training programmes. By summarising both established techniques and recent methodological advancements, this review aims to provide a comprehensive overview of the tools available in clinical practice for evaluating and treating respiratory muscle dysfunction. Our goal is to present a clear understanding of the current capabilities and limitations of these diagnostic and therapeutic approaches. Integrating advanced diagnostic methods and innovative treatment strategies should help improve patient management and outcomes. This comprehensive review serves as a resource for clinicians, equipping them with the necessary knowledge to effectively diagnose and treat respiratory muscle dysfunction in both acute and chronic respiratory failure scenarios.

Association of diaphragmatic dysfunction with duration of mechanical ventilation in patients in the pediatric intensive care unit: a prospective cohort study

BACKGROUND

Mechanical ventilation (MV) can cause diaphragmatic injury and ventilator induced diaphragmatic dysfunction (VIDD). Diaphragm ultrasonography (DU) is increasingly used to assess diaphragmatic anatomy, function and pathology of patients receiving MV in the pediatric intensive care unit (PICU). We report the poor contractile ability of diaphragm during ventilation of critically ill patients in our PICU and the association to prolonged length of MV and PICU stay.

METHODS

Patients who received MV within 24 h of admission to the PICU, expected to undergo continuous MV for more than 48 h and succeeded to extubate were included in the study. DU monitoring was performed daily after the initiation of MV until extubation. Diaphragm thickening fraction (DTF) measured by DU was used as an indicator of diaphragmatic contractile activity. Patients with bilateral DTF = 0% during DU assessment were allocated into the severe VIDD group (n = 26) and the rest were into non-severe VIDD group (n = 29). The association of severe VIDD with individual length of MV, hospitalization and PICU stay were analyzed.

RESULTS

With daily DU assessment, severe VIDD occurred on 2.9 ± 1.2 days after the initiation of MV, and lasted for 1.9 ± 1.7 days. Values of DTF of all patients recovered to > 10% before extubation. The severe VIDD group had a significantly longer duration (days) of MV [12.0 (8.0-19.3) vs. 5.0 (3.5-7.5), p < 0.001] and PICU stay (days) [30.5 (14.9-44.5) vs. 13.0 (7.0-24.5), p < 0.001]. The occurrence of severe VIDD, first day of severe VIDD and length of severe VIDD were significantly positively associated with the duration of MV and PICU stay. The occurrence of severe VIDD on the second and third days after initiation of MV significantly associated to longer PICU stay (days) [43.0 (9.0-70.0) vs. 13.0 (3.0-40.0), p = 0.009; 36.0 (17.0-208.0) vs. 13.0 (3.0-40.0), p = 0.005, respectively], and the length of MV (days) was significantly longer in those with severe VIDD on the third day after initiation of MV [16.5 (7.0-29.0) vs. 5.0 (2.0-22.0), p = 0.003].

CONCLUSIONS

Daily monitoring of diaphragmatic function with bedside ultrasonography after initiation of MV is necessary in critically ill patients in PICU and the influences and risk factors of severe VIDD need to be further studied. (355 words).

ICU patients receiving remifentanil do not experience reduced duration of mechanical ventilation: a systematic review of randomized controlled trials and network meta-analyses based on Bayesian theories

Background

The purpose of this network meta-analysis (NMA) was to evaluate the efficacy of intravenous opioid μ-receptor analgesics in shortening the duration of mechanical ventilation (MV) in ICU patients.

Methods

Randomized controlled trials comparing the efficacy of remifentanil, sufentanil, morphine, and fentanyl on the duration of MV in ICU patients were searched in Embase, Cochrane, Pubmed, and Web of Science electronic databases. The primary outcome was MV duration. The Bayesian random-effects framework was used to evaluate relative efficacy.

Results

In total 20 studies were included in this NMA involving 3,442 patients. Remifentanil was not associated with a reduction in the duration of MV compared with fentanyl (mean difference (MD) -0.16; 95% credible interval (CrI): -4.75 ~ 5.63) and morphine (MD 3.84; 95% CrI: -0.29 ~ 10.68). The secondary outcomes showed that, compared with remifentanil, sufentanil can prolong the duration of extubation. No regimen significantly shortened the ICU length of stay and improved the ICU mortality, efficacy, safety, and drug-related adverse events.

Conclusion

Among these analgesics, remifentanil did not appear to be associated with a reduction in MV duration. Clinicians should carefully titrate the analgesia of MV patients to prevent a potentially prolonged duration of MV due to excessive or inadequate analgesic therapy.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, CRD42021232604.

The ReInvigorate Study-phrenic nerve-to-diaphragm stimulation for weaning from mechanical ventilation: a protocol for a randomized pivotal clinical trial

BACKGROUND

In the United States in 2017, there were an estimated 903,745 hospitalizations involving mechanical ventilation (MV). Complications from ventilation can result in longer hospital stays, increased risk of disability, and increased healthcare costs. It has been hypothesized that electrically pacing the diaphragm by phrenic nerve stimulation during mechanical ventilation may minimize or reverse diaphragm dysfunction, resulting in faster weaning.

METHODS

The ReInvigorate Trial is a prospective, multicenter, randomized, controlled clinical trial evaluating the safety and efficacy of Stimdia's pdSTIM System for facilitating weaning from MV. The pdSTIM system employs percutaneously placed multipolar electrodes to stimulate the cervical phrenic nerves and activate contraction of the diaphragm bilaterally. Patients who were on mechanical ventilation for at least 96 h and who failed at least one weaning attempt were considered for enrollment in the study. The primary efficacy endpoint was the time to successful liberation from mechanical ventilation (treatment vs. control). Secondary endpoints will include the rapid shallow breathing index and other physiological and system characteristics. Safety will be summarized for both primary and additional analyses. All endpoints will be evaluated at 30 days or at the time of removal of mechanical ventilation, whichever is first.

DISCUSSION

This pivotal study is being conducted under an investigational device exception with the U.S. Food and Drug Administration. The technology being studied could provide a first-of-kind therapy for difficult-to-wean patients on mechanical ventilation in an intensive care unit setting.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT05998018 , registered August 2023.

Feasibility of veno-arterial extracorporeal life support in awake patients with cardiogenic shock

OBJECTIVES

This study sought to demonstrate outcomes of veno-arterial extracorporeal life support (VA-ECLS) in non-intubated ('awake') patients with cardiogenic shock, as very few studies have investigated safety and feasibility in this population.

METHODS

This was a retrospective review of 394 consecutive VA-ECLS patients at our institution from 2017 to 2021. We excluded patients cannulated for indications definitively associated with intubation. Patients were stratified by intubation status at time of cannulation and baseline differences were balanced by inverse probability of treatment weighting. The primary outcome was in-hospital mortality while secondary outcomes included adverse events during ECLS and destination at discharge.

RESULTS

Out of 135 patients in the final cohort, 79 were intubated and 56 were awake at time of cannulation. All awake patients underwent percutaneous femoral cannulation with technical success of 100% without intubation. Indications for VA-ECLS in awake patients included acute decompensated heart failure (64.3%), pulmonary hypertension or massive pulmonary embolism (12.5%), myocarditis (8.9%) and acute myocardial infarction (5.4%). After adjustment, awake and intubated patients had similar ECLS duration (7 vs 6 days, P = 0.19), in-hospital mortality (39.6% vs 51.7%, P = 0.28), and rates of various adverse events. Intubation status was not a significant risk factor for 90-day mortality (hazard ratio [95% confidence interval]: 1.26 [0.64, 2.45], P = 0.51) in multivariable analysis. Heart transplantation (15.1% vs 4.9%) and ventricular assist device (17.4% vs 2.2%) were more common destinations at discharge in awake patients than intubated patients (P = 0.02).

CONCLUSIONS

Awake VA-ECLS is safe and feasible with comparable outcomes as intubated counterparts in select cardiogenic shock patients.

Development of a machine learning model for prediction of the duration of unassisted spontaneous breathing in patients during prolonged weaning from mechanical ventilation

PURPOSE

Treatment of patients undergoing prolonged weaning from mechanical ventilation includes repeated spontaneous breathing trials (SBTs) without respiratory support, whose duration must be balanced critically to prevent over- and underload of respiratory musculature. This study aimed to develop a machine learning model to predict the duration of unassisted spontaneous breathing.

MATERIALS AND METHODS

Structured clinical data of patients from a specialized weaning unit were used to develop (1) a classifier model to qualitatively predict an increase of duration, (2) a regressor model to quantitatively predict the precise duration of SBTs on the next day, and (3) the duration difference between the current and following day. 61 features, known to influence weaning, were included into a Histogram-based gradient boosting model. The models were trained and evaluated using separated data sets.

RESULTS

18.948 patient-days from 1018 individual patients were included. The classifier model yielded an ROC-AUC of 0.713. The regressor models displayed a mean absolute error of 2:50 h for prediction of absolute durations and 2:47 h for day-to-day difference.

CONCLUSIONS

The developed machine learning model showed informed results when predicting the spontaneous breathing capacity of a patient in prolonged weaning, however lacking prognostic quality required for direct translation to clinical use.

Super-relaxed myosins contribute to respiratory muscle hibernation in mechanically ventilated patients

Patients receiving mechanical ventilation in the intensive care unit (ICU) frequently develop contractile weakness of the diaphragm. Consequently, they may experience difficulty weaning from mechanical ventilation, which increases mortality and poses a high economic burden. Because of a lack of knowledge regarding the molecular changes in the diaphragm, no treatment is currently available to improve diaphragm contractility. We compared diaphragm biopsies from ventilated ICU patients (N = 54) to those of non-ICU patients undergoing thoracic surgery (N = 27). By integrating data from myofiber force measurements, x-ray diffraction experiments, and biochemical assays with clinical data, we found that in myofibers isolated from the diaphragm of ventilated ICU patients, myosin is trapped in an energy-sparing, super-relaxed state, which impairs the binding of myosin to actin during diaphragm contraction. Studies on quadriceps biopsies of ICU patients and on the diaphragm of previously healthy mechanically ventilated rats suggested that the super-relaxed myosins are specific to the diaphragm and not a result of critical illness. Exposing slow- and fast-twitch myofibers isolated from the diaphragm biopsies to small-molecule compounds activating troponin restored contractile force in vitro. These findings support the continued development of drugs that target sarcomere proteins to increase the calcium sensitivity of myofibers for the treatment of ICU-acquired diaphragm weakness.

Impacts of three inspiratory muscle training programs on inspiratory muscles strength and endurance among intubated and mechanically ventilated patients with difficult weaning: a multicentre randomised controlled trial

BACKGROUND

Inspiratory muscle training (IMT) is well-established as a safe option for combating inspiratory muscles weakness in the intensive care setting. It could improve inspiratory muscle strength and decrease weaning duration but a lack of knowledge on the optimal training regimen raise to inconsistent results. We made the hypothesis that an innovative mixed intensity program for both endurance and strength improvement could be more effective. We conducted a multicentre randomised controlled parallel trial comparing the impacts of three IMT protocols (low, high, and mixed intensity) on inspiratory muscle strength and endurance among difficult-to-wean patients.

METHODS

Ninety-two patients were randomly assigned to three groups with different training programs, where each performed an IMT program twice daily, 7 days per week, from inclusion until successful extubation or 30 days. The primary outcome was maximal inspiratory pressure (MIP) increase. Secondary outcomes included peak pressure (Ppk) increase as an endurance marker, mechanical ventilation (MV) duration, ICU length of stay, weaning success defined by a 2-day ventilator-free after extubation, reintubation rate and safety.

RESULTS

MIP increases were 10.8 ± 11.9 cmH2O, 4.5 ± 14.8 cmH2O, and 6.7 ± 14.5 cmH2O for the mixed intensity (MI), low intensity (LI), and high intensity (HI) groups, respectively. There was a non-statistically difference between the MI and LI groups (mean adjusted difference: 6.59, 97.5% CI [- 14.36; 1.18], p = 0.056); there was no difference between the MI and HI groups (mean adjusted difference: - 3.52, 97.5% CI [- 11.57; 4.53], p = 0.321). No significant differences in Ppk increase were observed among the three groups. Weaning success rate observed in MI, HI and LI group were 83.7% [95% CI 69.3; 93.2], 82.6% [95% CI 61.2; 95.0] and 73.9% [95% CI 51.6; 89.8], respectively. MV duration, ICU length of stay and reintubation rate had similar values. Over 629 IMT sessions, six adverse events including four spontaneously reversible bradycardia in LI group were possibly related to the study.

CONCLUSIONS

Among difficult-to-wean patients receiving invasive MV, no statistically difference was observed in strength and endurance progression across three different IMT programs. IMT appears to be feasible in usual cares, but some serious adverse events such as bradycardia could motivate further research on the specific impact on cardiac system. Trial registration Clinicaltrials.gov identifier: NCT02855619. Registered 28 September 2014.

Operator independent continuous ultrasound monitoring of diaphragm excursion predicts successful weaning from mechanical ventilation: a prospective observational study

BACKGROUND

In mechanically ventilated patients, diaphragm ultrasound can identify diaphragm weakness and predict weaning failure. We evaluated whether a novel operator-independent ultrasound-based medical device allowing continuous monitoring of the diaphragm (CUSdi) could reliably (1) measure diaphragm excursion (EXdi) and peak contraction velocity (PCVdi), (2) predict weaning outcome, and (3) approximate transdiaphragmatic pressure (Pdi).

METHODS

In 49 mechanically ventilated patients, CUSdi was recorded during a 30-min spontaneous breathing trial (SBT), and EXdi and PCVdi were measured. In subgroups of patients, standard ultrasound measurement of EXdi and PCVdi was performed (n = 36), and Pdi derived parameters (peak and pressure time product, n = 30) were measured simultaneously.

RESULTS

The agreement bias between standard ultrasound and CUSdi for EXdi was 0.1 cm (95% confidence interval -0.7-0.9 cm). The regression of Passing-Bablok indicated a lack of systematic difference between EXdi measured with standard ultrasound and CUSdi, which were positively correlated (Rho = 0.84, p < 0.001). Weaning failure was observed in 54% of patients. One, two and three minutes after the onset of the SBT, EXdi was higher in the weaning success group than in the failure group. Two minutes after the onset of the SBT, an EXdi < 1.1 cm predicted weaning failure with a sensitivity of 0.83, a specificity of 0.68, a positive predictive value of 0.76, and a negative predictive value of 0.24. There was a weak correlation between EXdi and both peak Pdi (r = 0.22, 95% confidence interval 0.15 - 0.28) and pressure time product (r = 0.13, 95% confidence interval 0.06 - 0.20). Similar results were observed with PCVdi.

CONCLUSIONS

Operator-independent continuous diaphragm monitoring quantifies EXdi reliably and can predict weaning failure with an identified cut-off value of 1.1 cm. Trial registration clinicaltrial.gov, NCT04008875 (submitted 12 April 2019, posted 5 July 2019) and NCT03896048 (submitted 27 March 2019, posted 29 March 2019).

High Airway Occlusion Pressure Is Associated with Dyspnea and Increased Mortality in Critically Ill Mechanically Ventilated Patients

Rationale: Airway occlusion pressure at 100 ms (P0.1) reflects central respiratory drive. Objectives: We aimed to assess factors associated with P0.1 and whether an abnormally low or high P0.1 value is associated with higher mortality and longer duration of mechanical ventilation (MV). Methods: We performed a secondary analysis of a prospective cohort study conducted in 10 ICUs in France to evaluate dyspnea in communicative MV patients. In patients intubated for more than 24 hours, P0.1 was measured with dyspnea as soon as patients could communicate and the next day. Measurements and Main Results: Among 260 patients assessed after a median time of ventilation of 4 days, P0.1 was 1.9 (1-3.5) cm H2O at enrollment, 24% had P0.1 values >3.5 cm H2O, 37% had P0.1 values between 1.5 and 3.5 cm H2O, and 39% had P0.1 values <1.5 cm H2O. In multivariable linear regression, independent factors associated with P0.1 were the presence of dyspnea (P = 0.037), respiratory rate (P < 0.001), and PaO2 (P = 0.008). Ninety-day mortality was 33% in patients with P0.1 > 3.5 cm H2O versus 19% in those with P0.1 between 1.5 and 3.5 cm H2O and 17% in those with P0.1 < 1.5 cm H2O (P = 0.046). After adjustment for the main risk factors, P0.1 was associated with 90-day mortality (hazard ratio per 1 cm H2O, 1.19 [95% confidence interval, 1.04-1.37]; P = 0.011). P0.1 was also independently associated with a longer duration of MV (hazard ratio per 1 cm H2O, 1.10 [95% confidence interval, 1.02-1.19]; P = 0.016). Conclusions: In patients receiving invasive MV, abnormally high P0.1 values may suggest dyspnea and are associated with higher mortality and prolonged duration of MV.

Ultrasonographic Assessment of the Diaphragm

Mechanical ventilation injures not only the lungs but also the diaphragm, resulting in dysfunction associated with poor outcomes. Diaphragm ultrasonography is a noninvasive, cost-effective, and reproducible diagnostic method used to monitor the condition and function of the diaphragm. With advances in ultrasound technology and the expansion of its clinical applications, diaphragm ultrasonography has become increasingly important as a tool to visualize and quantify diaphragmatic morphology and function across multiple medical specialties, including pulmonology, critical care, and rehabilitation medicine. This comprehensive review aims to provide an in-depth analysis of the role and limitations of ultrasonography in assessing the diaphragm, especially among critically ill patients. Furthermore, we discuss a recently published expert consensus and provide a perspective for the future.

EFFECTS OF LEVOSIMENDAN ON DIAPHRAGMATIC DYSFUNCTION IN PATIENTS WITH SEPSIS

ABSTRACT

Objective: In this study, our aim was to examine the effects of levosimendan on diaphragmatic dysfunction in patients with sepsis, as well as assess its impact on respiratory muscle contractility and the outcome of weaning. Methods: This was a single-blind, randomized, controlled trial. Patients with diaphragmatic dysfunction and failure of spontaneous breathing trials (SBTs) were randomly and equally assigned to the experimental and control groups. The experimental group received levosimendan at a loading dose of 6 μg/kg for 10 min, followed by a continuous infusion at 0.2 μg/kg/min. The control group received an equivalent dose of a placebo. The preadministration and postadministration respiratory mechanics parameters of the patients were recorded. Evaluation of the effect of levosimendan on patients with sepsis-induced diaphragm dysfunction comprised arterial blood gas analysis as well as ultrasound measurements of diaphragm excursion (DE), diaphragm thickness (DT), diaphragm thickening fraction (TFdi), and diaphragm-rapid shallow breathing index (D-RSBI). Results: Forty-four patients were enrolled in the study. We found that postadministration of levosimendan, the patients' tidal volume (GCSMV) increased, whereas the D-RSBI decreased, and the partial pressure of carbon dioxide (PACO 2 ) decreased when compared to the preadministration levels. Additionally, following levosimendan administration, patients showed increased DE and pressure support (PS) when compared to before administration (1.14 ± 0.177 vs. 1.22 ± 0.170 cm and 0.248 ± 0.03 vs. 0.284 ± 0.06, respectively) and decreased D-RSBI (22.76 ± 6.14 vs. 20.06 ± 6.04, respectively), all of which were statistically significant ( P < 0.05). In contrast, in the control group of patients, there were no statistically significant differences in the postadministration levels of DE, TFdi, and D-RSBI as compared to the preadministration period ( P > 0.05). Furthermore, in terms of weaning outcomes, we did not find any statistically significant difference in the number of patients in the two groups who eventually underwent weaning ( P = 0.545). Conclusion: In this study, we found that levosimendan enhanced diaphragm contractile function. However, further investigations are required to explore its effect on weaning outcomes in patients undergoing mechanical ventilation.