Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Volatile anesthetics for lung- and diaphragm-protective sedation

This review explores the complex interactions between sedation and invasive ventilation and examines the potential of volatile anesthetics for lung- and diaphragm-protective sedation. In the early stages of invasive ventilation, many critically ill patients experience insufficient respiratory drive and effort, leading to compromised diaphragm function. Compared with common intravenous agents, inhaled sedation with volatile anesthetics better preserves respiratory drive, potentially helping to maintain diaphragm function during prolonged periods of invasive ventilation. In turn, higher concentrations of volatile anesthetics reduce the size of spontaneously generated tidal volumes, potentially reducing lung stress and strain and with that the risk of self-inflicted lung injury. Taken together, inhaled sedation may allow titration of respiratory drive to maintain inspiratory efforts within lung- and diaphragm-protective ranges. Particularly in patients who are expected to require prolonged invasive ventilation, in whom the restoration of adequate but safe inspiratory effort is crucial for successful weaning, inhaled sedation represents an attractive option for lung- and diaphragm-protective sedation. A technical limitation is ventilatory dead space introduced by volatile anesthetic reflectors, although this impact is minimal and comparable to ventilation with heat and moisture exchangers. Further studies are imperative for a comprehensive understanding of the specific effects of inhaled sedation on respiratory drive and effort and, ultimately, how this translates into patient-centered outcomes in critically ill patients.

Weaning from mechanical ventilation during myasthenic crisis, a monocentric retrospective study

Mechanical ventilation in myasthenic crisis is not standardized and is at high risk of failure. We investigated liberation from mechanical ventilation during myasthenic crisis using a prolonged spontaneous breathing trials (SBT) and sequential pulmonary function tests (PFT). In this retrospective monocenter study, we included patients admitted for a first episode of myasthenic crisis between January 2001 and January 2018. The primary outcome was the incidence of weaning failure upon first extubation in our cohort of patients with MC. Secondary objectives were to determine risk factors and outcome associated with weaning failure upon first extubation in MC. We also compared the characteristics of patients with prolonged weaning. 126 episodes of MC were analyzed. Patient's age was 64 [42-76] years with 72/126 (56.5%) being women. The median delay between weaning initiation and first extubation was 6 [3-10] days and the median total length of MV was 14 [10-23] days. 118/126 (93.7%) patients underwent prolonged SBT of 8 h or more prior to first extubation. The overall weaning failure rate was 18/126 (14.3%). Extubation was more often successful when the factor precipitating the myasthenic crisis was identified (86/108 (79.6%) vs. 8/18 (44.4%); p = 0.004), whereas PFT was similar in failure or successes. Most weaning failures upon first extubation attempt (11/18; 61%) were attributed to an insufficient stabilization of myasthenia gravis. Duration of mechanical ventilation, an infectious trigger and maximal inspiratory pressure upon intubation were independent risk factors for prolonged weaning. In myasthenic crisis, a standardized protocol including prolonged SBT and respiratory function tests might improve the success of first extubation without prolonging mechanical ventilation. The results of this single center study warrant further evaluation in interventional trials.

Physicians' decision making when weaning patients from mechanical ventilation: A qualitative content analysis

BACKGROUND

Weaning from mechanical ventilation is a complex and central intensive care process. This complexity indicates that the challenges of weaning must be explored from different perspectives. Furthermore, physicians' experiences and the factors influencing their decision-making regarding weaning are unclear.

OBJECTIVES

This study aimed to explore and describe the factors influencing physicians' decision-making when weaning patients from invasive mechanical ventilation in Swedish intensive care units (ICUs).

METHODS

This qualitative study used an exploratory and descriptive design with qualitative content analysis. Sixteen physicians from five ICUs across Sweden were purposively included and interviewed regarding their weaning experiences.

FINDINGS

The physicians expressed that prioritising the patient's well-being was evident, and there was agreement that both the physical and mental condition of the patient had a substantial impact on decision-making. Furthermore, there was a lack of agreement on whether patients should be involved in the weaning process and how their resources, needs, and wishes should be included in decision-making. In addition, there were factors not directly linked to the patient but which still influenced decision-making, such as the available resources and teamwork. Sometimes, it was difficult to point out the basis for decisions; in that decisions were made by gut feeling, intuition, or clinical experience.

CONCLUSION

Physicians' decision-making regarding weaning was a dynamic process influenced by several factors. These factors were related to the patient's condition and the structure for weaning. Increased understanding of weaning from the physicians' and ICU teams' perspectives may improve the weaning process by broadening the knowledge about the aspects influencing the decision-making.

Factors that influence critical care nurses' management of sedation for ventilated patients in critical care: A qualitative study

BACKGROUND

Optimising sedation use is key to timely extubation. Whilst sedation protocols may be used to guide critical care nurses' management of sedation, sedation management and decision-making is complex, influenced by multiple factors related to patients' circumstances, intensive care unit design and the workforce.

AIM

To explore (i) critical care nurses' experiences managing sedation in mechanically ventilated patients and (ii) the factors that influence their sedation-related decision-making.

DESIGN

Qualitative descriptive study using semi-structured interviews. Data were analysed using Braun and Clarke's six-step thematic analysis.

SETTING AND PARTICIPANTS

This study was conducted in a 26-bed level 3 accredited ICU, in a private hospital in Melbourne, Australia. The majority of patients are admitted following elective surgery. Critical care nurses, who were permanently employed as a registered nurse, worked at least 16 h per week, and cared for ventilated patients, were invited to participate.

FINDINGS

Thirteen critical care nurses participated. Initially, participants suggested their experiences managing sedation were linked to local unit policy and learning. Further exploration revealed that experiences were synonymous with descriptors of factors influencing sedation decision-making according to three themes: (i) Learning from past experiences, (ii) Situational awareness and (iii) Prioritising safety. Nurses relied on their cumulative knowledge from prior experiences to guide decision-making. Situational awareness about other emergent priorities in the unit, staffing and skill-mix were important factors in guiding sedation decision-making. Safety of patients and staff was essential, at times overriding goals to reduce sedation.

CONCLUSION

Sedation decision making cannot be considered in isolation. Rather, sedation decision making must take into account outcomes of patient assessment, emergent priorities, unit and staffing factors and safety concerns.

IMPLICATIONS FOR CLINICAL PRACTICE

Opportunities for ongoing education are essential to promote nurses' situational awareness of other emergent unit priorities, staffing and skill-mix, in addition to evidence-based sedation management and decision making.

Retrospective service evaluation of a specialist weaning unit

Specialist weaning units (SWUs) aim to liberate patients with complex weaning failure from mechanical ventilation and facilitate their discharge from the ICU. This retrospective service evaluation reports the outcomes of a SWU at Wythenshawe Hospital, Manchester between 2017 and 2019. In total, 75.0% (n = 33/44) of patients survived to hospital discharge. Of these patients, 72.7% (n = 24/33) were self-ventilating. Overall, 1-year survival was 68.2% (n = 30/44), whilst 5-year survival was 52.3% (n = 23/44). Whilst this study is relatively small, these findings are encouraging and further support the case for SWUs.

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.

Effect of lung volume preservation during spontaneous breathing trial on successful extubation in patients receiving mechanical ventilation: protocol for a multicenter clinical trial

BACKGROUND

In standard weaning from mechanical ventilation, a successful spontaneous breathing test (SBT) consisting of 30 min 8 cmH2O pressure-support ventilation (PSV8) without positive end-expiratory pressure (PEEP) is followed by extubation with continuous suctioning; however, these practices might promote derecruitment. Evidence supports the feasibility and safety of extubation without suctioning. Ultrasound can assess lung aeration and respiratory muscles. We hypothesize that weaning aiming to preserve lung volume can yield higher rates of successful extubation.

METHODS

This multicenter superiority trial will randomly assign eligible patients to receive either standard weaning [SBT: 30-min PSV8 without PEEP followed by extubation with continuous suctioning] or lung-volume-preservation weaning [SBT: 30-min PSV8 + 5 cmH2O PEEP followed by extubation with positive pressure without suctioning]. We will compare the rates of successful extubation and reintubation, ICU and hospital stays, and ultrasound measurements of the volume of aerated lung (modified lung ultrasound score), diaphragm and intercostal muscle thickness, and thickening fraction before and after successful or failed SBT. Patients will be followed for 90 days after randomization.

DISCUSSION

We aim to recruit a large sample of representative patients (N = 1600). Our study cannot elucidate the specific effects of PEEP during SBT and of positive pressure during extubation; the results will show the joint effects derived from the synergy of these two factors. Although universal ultrasound monitoring of lungs, diaphragm, and intercostal muscles throughout weaning is unfeasible, if derecruitment is a major cause of weaning failure, ultrasound may help clinicians decide about extubation in high-risk and borderline patients.

TRIAL REGISTRATION

The Research Ethics Committee (CEIm) of the Fundació Unió Catalana d'Hospitals approved the study (CEI 22/67 and 23/26). Registered at ClinicalTrials.gov in August 2023. Identifier: NCT05526053.

Mechanical power density, spontaneous breathing indexes, and prolonged weaning failure: a prospective cohort study

A prospective observational study comparing mechanical power density (MP normalized to dynamic compliance) with traditional spontaneous breathing indexes (e.g., predicted body weight normalized tidal volume [VT/PBW], rapid shallow breathing index [RSBI], or the integrative weaning index [IWI]) for predicting prolonged weaning failure in 140 tracheotomized patients. We assessed the diagnostic accuracy of these indexes at the start and end of the weaning procedure using ROC curve analysis, expressed as the area under the receiver operating characteristic curve (AUROC). Weaning failure occurred in 41 out of 140 patients (29%), demonstrating significantly higher MP density (6156 cmH2O2/min [4402-7910] vs. 3004 cmH2O2/min [2153-3917], P < 0.01), lower spontaneous VT/PBW (5.8 mL*kg-1 [4.8-6.8] vs. 6.6 mL*kg-1 [5.7-7.9], P < 0.01) higher RSBI (68 min-1*L-1 [44-91] vs. 55 min-1*L-1 [41-76], P < 0.01) and lower IWI (41 L2/cmH2O*%*min*10-3 [25-72] vs. 71 L2/cmH2O*%*min*10-3 [50-106], P < 0.01) and at the end of weaning. MP density was more accurate at predicting weaning failures (AUROC 0.91 [95%CI 0.84-0.95]) than VT/PBW (0.67 [0.58-0.74]), RSBI (0.62 [0.53-0.70]), or IWI (0.73 [0.65-0.80]), and may help clinicians in identifying patients at high risk for long-term ventilator dependency.

Impact of tracheostomy tube modalities on ventilatory mechanics: a bench study

PURPOSE

Tracheostomized patients often present with muscle weakness, altered consciousness, or swallowing difficulties. Hence, the literature is scarce regarding the challenging management of tracheostomy weaning. There is a need to strengthen the understanding of respiratory mechanisms with the different tracheostomy tube modalities that compose this weaning pathway. We aimed to evaluate the impact of these modalities on the work of breathing (WOB), total positive end-expiratory pressure (PEEPtot), and tidal volume (VT).

METHODS

With a three-dimensional (3D) printed head mimicking human upper airways, we added a tracheal extension, and pierced to allow insertion of a size 7.0 tracheostomy cannula. The whole was connected to an artificial lung. Three lung mechanics were simulated (normal, obstructive and restrictive). We compared five different tracheostomy tube modalities to a control scenario in which the tube was capped and the cuff was deflated.

RESULTS

A marginal difference was observed on the WOB within conditions with a slight increase + 0.004 [95% CI (0.003-0.004); p < 0.001] when the cuff was inflated in the normal and restrictive models and a slight decrease in the obstructive model. The highest PEEPtot that was reached was + 1 cmH2O [95% CI (1-1.1); p < 0.001] with high-flow therapy (HFT) with the cuff inflated in the obstructive model. We observed a statistically significant reduction in VT [up to - 57 mL 95% CI (- 60 to - 54); p < 0.001] when the cuff was inflated, in both the normal and obstructive models.

CONCLUSIONS

Our results support the use of conditions that involve cuff deflation. Intermediate modalities with the cuff deflated produced similar results than cannula capping.

Contextual design requirements for decision-support tools involved in weaning patients from mechanical ventilation in intensive care units

Weaning patients from ventilation in intensive care units (ICU) is a complex task. There is a growing desire to build decision-support tools to help clinicians during this process, especially those employing Artificial Intelligence (AI). However, tools built for this purpose should fit within and ideally improve the current work environment, to ensure they can successfully integrate into clinical practice. To do so, it is important to identify areas where decision-support tools may aid clinicians, and associated design requirements for such tools. This study analysed the work context surrounding the weaning process from mechanical ventilation in ICU environments, via cognitive task and work domain analyses. In doing so, both what cognitive processes clinicians perform during weaning, and the constraints and affordances of the work environment itself, were described. This study found a number of weaning process tasks where decision-support tools may prove beneficial, and from these a set of contextual design requirements were created. This work benefits researchers interested in creating human-centred decision-support tools for mechanical ventilation that are sensitive to the wider work system.

In-hospital mortality, comorbidities, and costs of one million mechanically ventilated patients in Germany: a nationwide observational study before, during, and after the COVID-19 pandemic

Background

Even more than hospital care in general, intensive care and mechanical ventilation capacities and its utilization in terms of rates, indications, ventilation types and outcomes vary largely among countries. We analyzed complete and nationwide data for Germany, a country with a large intensive care sector, before, during and after the COVID-19 pandemic.

Methods

Analysis of administrative claims data, provided by the German health insurance, from all hospitals for all individual patients who were mechanically ventilated between 2019 and 2022. The data included age, sex, diagnoses, length of stay, procedures (e.g., form and duration of mechanical ventilation), outcome (dead vs. alive) and costs. We included all patients who were at least 18 years old at the time of discharge from January 1st, 2019 to December 31st, 2022. Patients were grouped according to year, age group and the form of mechanical ventilation. We further analyzed subgroups of patients being resuscitated and those being COVID-19 positive (vs. negative).

Findings

During the four years, 1,003,882 patients were mechanically ventilated in 1395 hospitals. Rates per 100,000 inhabitants varied across age groups from 110 to 123 (18-59 years) to 1101-1275 (>80 years). The top main diagnoses were other forms of heart diseases, pneumonia, chronic obstructive pulmonary disease (COPD), ischemic heart diseases and cerebrovascular diseases. 43.3% (437,031/1,003,882) of all mechanically ventilated patients died in hospital with a remarkable increase in mortality with age and from 2019 to 2022 by almost 5%-points. The in-hospital mortality of ventilated COVID-19 patients was 53.7% (46,553/86,729), while it was 42.6% (390,478/917,153) in non-COVID patients. In-hospital mortality varied from 27.0% in non-invasive mechanical ventilation (NIV) only to 53.4% in invasive mechanical ventilation only cases, 59.4% with early NIV failure, 68.6% with late NIV failure, to 74.0% in patients receiving VV-ECMO and 80.0% in VA-ECMO. 17.5% of mechanically ventilated patients had been resuscitated before, of whom 78.2% (153,762/196,750) died. Total expenditure was around 6 billion Euros per year, i.e. 0.17% of the German GDP.

Interpretation

Mechanical ventilation was widely used, before, during and after the COVID-19 pandemic in Germany, reaching more than 1000 patients per 100,000 inhabitants per year in the age over 80 years. In-hospital mortality rates in this nationwide and complete cohort exceeded most of the data known by far.

Funding

This research did not receive any dedicated funding.

Outcomes of different pulmonary rehabilitation protocols in patients under mechanical ventilation with difficult weaning: a retrospective cohort study

BACKGROUND

The endeavor of liberating patients from ventilator dependence within respiratory care centers (RCCs) poses considerable challenges. Multiple factors contribute to this process, yet establishing an effective regimen for pulmonary rehabilitation (PR) remains uncertain. This retrospective study aimed to evaluate existing rehabilitation protocols, ascertain associations between clinical factors and patient outcomes, and explore the influence of these protocols on the outcomes of the patients to shape suitable rehabilitation programs.

METHODS

Conducted at a medical center in northern Taiwan, the retrospective study examined 320 newly admitted RCC patients between January 1, 2015, and December 31, 2017. Each patient received a tailored PR protocol, following which researchers evaluated weaning rates, RCC survival, and 3-month survival as outcome variables. Analyses scrutinized differences in baseline characteristics and prognoses among three PR protocols: protocol 1 (routine care), protocol 2 (routine care plus breathing training), and protocol 3 (routine care plus breathing and limb muscle training).

RESULTS

Among the patients, 28.75% followed protocol 1, 59.37% protocol 2, and 11.88% protocol 3. Variances in age, body-mass index, pneumonia diagnosis, do-not-resuscitate orders, Glasgow Coma Scale scores (≤ 14), and Acute Physiology and Chronic Health Evaluation II (APACHE) scores were notable across these protocols. Age, APACHE scores, and abnormal blood urea nitrogen levels (> 20 mg/dL) significantly correlated with outcomes-such as weaning, RCC survival, and 3-month survival. Elevated mean hemoglobin levels linked to increased weaning rates (p = 0.0065) and 3-month survival (p = 0.0102). Four adjusted models clarified the impact of rehabilitation protocols. Notably, the PR protocol 3 group exhibited significantly higher 3-month survival rates compared to protocol 1, with odds ratios (ORs) ranging from 3.87 to 3.97 across models. This association persisted when comparing with protocol 2, with ORs between 3.92 and 4.22.

CONCLUSION

Our study showed that distinct PR protocols significantly affected the outcomes of ventilator-dependent patients within RCCs. The study underlines the importance of tailored rehabilitation programs and identifies key clinical factors influencing patient outcomes. Recommendations advocate prospective studies with larger cohorts to comprehensively assess PR effects on RCC patients.

Advanced waveform analysis of diaphragm surface EMG allows for continuous non-invasive assessment of respiratory effort in critically ill patients at different PEEP levels

BACKGROUND

Respiratory effort should be closely monitored in mechanically ventilated ICU patients to avoid both overassistance and underassistance. Surface electromyography of the diaphragm (sEMGdi) offers a continuous and non-invasive modality to assess respiratory effort based on neuromuscular coupling (NMCdi). The sEMGdi derived electrical activity of the diaphragm (sEAdi) is prone to distortion by crosstalk from other muscles including the heart, hindering its widespread use in clinical practice. We developed an advanced analysis as well as quality criteria for sEAdi waveforms and investigated the effects of clinically relevant levels of PEEP on non-invasive NMCdi.

METHODS

NMCdi was derived by dividing end-expiratory occlusion pressure (Pocc) by sEAdi, based on three consecutive Pocc manoeuvres at four incremental (+ 2 cmH2O/step) PEEP levels in stable ICU patients on pressure support ventilation. Pocc and sEAdi quality was assessed by applying a novel, automated advanced signal analysis, based on tolerant and strict cut-off criteria, and excluding inadequate waveforms. The coefficient of variations (CoV) of NMCdi after basic manual and automated advanced quality assessment were evaluated, as well as the effect of an incremental PEEP trial on NMCdi.

RESULTS

593 manoeuvres were obtained from 42 PEEP trials in 17 ICU patients. Waveform exclusion was primarily based on low sEAdi signal-to-noise ratio (Ntolerant = 155, 37%, Nstrict = 241, 51% waveforms excluded), irregular or abrupt cessation of Pocc (Ntolerant = 145, 35%, Nstrict = 145, 31%), and high sEAdi area under the baseline (Ntolerant = 94, 23%, Nstrict = 79, 17%). Strict automated assessment allowed to reduce CoV of NMCdi to 15% from 37% for basic quality assessment. As PEEP was increased, NMCdi decreased significantly by 4.9 percentage point per cmH2O.

CONCLUSION

Advanced signal analysis of both Pocc and sEAdi greatly facilitates automated and well-defined identification of high-quality waveforms. In the critically ill, this approach allowed to demonstrate a dynamic NMCdi (Pocc/sEAdi) decrease upon PEEP increments, emphasising that sEAdi-based assessment of respiratory effort should be related to PEEP dependent diaphragm function. This novel, non-invasive methodology forms an important methodological foundation for more robust, continuous, and comprehensive assessment of respiratory effort at the bedside.

Physiologic Effects of Reconnection to the Ventilator for 1 Hour Following a Successful Spontaneous Breathing Trial

BACKGROUND

Reconnection to the ventilator for 1 h following a successful spontaneous breathing trial (SBT) may reduce reintubation rates compared with direct extubation. However, the physiologic mechanisms leading to this effect are unclear.

RESEARCH QUESTION

Does reconnection to the ventilator for 1 h reverse alveolar derecruitment induced by SBT, and is alveolar derecruitment more pronounced with a T-piece than with pressure-support ventilation (PSV)?

STUDY DESIGN AND METHODS

This is an ancillary study of a randomized clinical trial comparing SBT performed with a T-piece or with PSV. Alveolar recruitment was assessed by using measurement of end-expiratory lung volume (EELV).

RESULTS

Of the 25 patients analyzed following successful SBT, 11 underwent SBT with a T-piece and 14 with PSV. At the end of the SBT, EELV decreased by -30% (95% CI, -37 to -23) compared with baseline prior to the SBT. This reduction was greater with a T-piece than with PSV: -43% (95% CI, -51 to -35) vs -20% (95% CI, -26 to -13); P < .001. Following reconnection to the ventilator for 1 h, EELV accounted for 96% (95% CI, 92 to 101) of baseline EELV and did not significantly differ from prior to the SBT (P = .104). Following 10 min of reconnection to the ventilator, EELV wasted at the end of the SBT was completely recovered using PSV (P = .574), whereas it remained lower than prior to the SBT using a T-piece (P = .010).

INTERPRETATION

Significant alveolar derecruitment was observed at the end of an SBT and was markedly more pronounced with a T-piece than with PSV. Reconnection to the ventilator for 1 h allowed complete recovery of alveolar derecruitment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT04227639; URL: www.

CLINICALTRIALS

gov.

The Value of Ischemic Cardiac Biomarkers to Predict Spontaneous Breathing Trial or Extubation Failure: A Systematic Review

Background: It is unclear whether other cardiac biomarkers than NT-proBNP can be useful in the risk stratification of patients weaning from mechanical ventilation. The aim of this study is to summarize the role of ischemic cardiac biomarkers in predicting spontaneous breathing trial (SBT) or extubation failure. Methods: We systematically searched Embase, MEDLINE, Web of Science, and Cochrane Central for studies published before January 2024 that reported the association between ischemic cardiac biomarkers and SBT or extubation failure. Data were extracted using a standardized form and methodological assessment was performed using the QUIPS tool. Results: Seven observational studies investigating four ischemic cardiac biomarkers (Troponin-T, Troponin-I, CK-MB, Myoglobin) were included. One study reported a higher peak Troponin-I in patients with extubation failure compared to extubation success (50 ng/L [IQR, 20-215] versus 30 ng/L [IQR, 10-86], p = 0.01). A second study found that Troponin-I measured before the SBT was higher in patients with SBT failure in comparison to patients with SBT success (100 ± 80 ng/L versus 70 ± 130 ng/L, p = 0.03). A third study reported a higher CK-MB measured at the end of the SBT in patients with weaning failure (SBT or extubation failure) in comparison to weaning success (8.77 ± 20.5 ng/mL versus 1.52 ± 1.42 ng/mL, p = 0.047). Troponin-T and Myoglobin as well as Troponin-I and CK-MB measured at other time points were not found to be related to SBT or extubation failure. However, most studies were underpowered and with high risk of bias. Conclusions: The association with SBT or extubation failure is limited for Troponin-I and CK-MB and appears absent for Troponin-T and Myoglobin, but available studies are hampered by significant methodological drawbacks. To more definitively determine the role of ischemic cardiac biomarkers, future studies should prioritize larger sample sizes, including patients at risk of cardiac disease, using stringent SBTs and structured timing of laboratory measurements before and after SBT.

Quantifying Diaphragm Blood Flow With Contrast-Enhanced Ultrasound in Humans

BACKGROUND

Despite the known interplay between blood flow and function, to our knowledge, there is currently no minimally invasive method to monitor diaphragm hemodynamics. We used contrast-enhanced ultrasound to quantify relative diaphragm blood flow (Q˙DIA) in humans and assessed the technique's efficacy and reliability during graded inspiratory pressure threshold loading. We hypothesized that: (1) Q˙DIA would linearly increase with pressure generation, and (2) that there would be good test-retest reliability and interanalyzer reproducibility.

RESEARCH QUESTION

Can we validate what is, to our knowledge, the first minimally invasive method to measure relative diaphragm blood flow in humans?

STUDY DESIGN AND METHODS

Quantitative contrast-enhanced ultrasound of the costal diaphragm was performed in healthy participants (10 male participants, 6 female participants; mean age 28 ± 5 years; BMI 22.8 ± 2.0 kg/m) during unloaded breathing and three stages of loaded breathing on two separate days. Gastric and esophageal balloon catheters measured transdiaphragmatic pressure. Ultrasonography was performed during a constant-rate IV infusion of lipid-stabilized microbubbles following each stage. Ultrasound images were acquired after a destruction-replenishment sequence and diaphragm specific time-intensity data were used to determine Q˙DIA by two individuals.

RESULTS

Transdiaphragmatic pressure for unloaded and each loading stage were 15.2 ± 0.8, 26.1 ± 0.8, 34.6 ± 0.8, and 40.0 ± 0.8 percentage of the maximum, respectively. Q˙DIA increased with each stage of loading (3.1 ± 3.1, 6.9 ± 3.6, 11.0 ± 4.9, and 13.5 ± 5.4 acoustic units/s; P < .0001). The linear relationship between diaphragmatic flow and pressure was reproducible from day to day. Q˙DIA had good to excellent test-retest reliability (0.86 [0.77, 0.92]; P < .0001) and excellent interanalyzer reproducibility (0.93 [0.90, 0.95]; P < .0001) with minimal bias.

INTERPRETATION

Relative Q˙DIA measurements had valid physiological underpinnings, were reliable day-to-day, and were reproducible analyzer-to-analyzer. This study indicated that contrast-enhanced ultrasound is a viable, minimally invasive method for assessing costal Q˙DIA in humans and may provide a tool to monitor diaphragm hemodynamics in clinical settings.

Combined cardiac, lung, and diaphragm ultrasound for predicting weaning failure during spontaneous breathing trial

BACKGROUND

Weaning from invasive mechanical ventilation (MV) is a complex and challenging process that involves multiple pathophysiological mechanisms. A combined ultrasound evaluation of the heart, lungs, and diaphragm during the weaning phase can help to identify risk factors and underlying mechanisms for weaning failure. This study aimed to investigate the accuracy of lung ultrasound (LUS), transthoracic echocardiography (TTE), and diaphragm ultrasound for predicting weaning failure in critically ill patients.

METHODS

Patients undergoing invasive MV for > 48 h and who were readied for their first spontaneous breathing trial (SBT) were studied. Patients were scheduled for a 2-h SBT using low-level pressure support ventilation. LUS and TTE were performed prospectively before and 30 min after starting the SBT, and diaphragm ultrasound was only performed 30 min after starting the SBT. Weaning failure was defined as failure of SBT, re-intubation, or non-invasive ventilation within 48 h.

RESULTS

Fifty-one patients were included, of whom 15 experienced weaning failure. During the SBT, the global, anterior, and antero-lateral LUS scores were higher in the failed group than in the successful group. Receiver operating characteristic curve analysis showed that the areas under the curves for diaphragm thickening fraction (DTF) and global and antero-lateral LUS scores during the SBT to predict weaning failure were 0.678, 0.719, and 0.721, respectively. There was no correlation between the LUS scores and the average E/e' ratio during the SBT. Multivariate analysis identified antero-lateral LUS score > 7 and DTF < 31% during the SBT as independent predictors of weaning failure.

CONCLUSION

LUS and diaphragm ultrasound can help to predict weaning failure in patients undergoing an SBT with low-level pressure support. An antero-lateral LUS score > 7 and DTF < 31% during the SBT were associated with weaning failure.

E-learning-an interventional element of the PRiVENT project to improve weaning expertise

BACKGROUND

PRiVENT (PRevention of invasive VENTilation) is an evaluation of a bundle of interventions aimed at the prevention of long-term invasive mechanical ventilation. One of these elements is an e-learning course for healthcare professionals to improve weaning expertise. The aim of our analysis is to examine the implementation of the course in cooperating intensive care units.

METHODS

The course has been developed through a peer review process by pulmonary and critical care physicians in collaboration with respiratory therapists, supported by health services researchers and a professional e-learning agency. The e-learning platform "weLearn" was made available online to participating healthcare professionals. Feedback on the e-learning programme was obtained and discussed in quality circles (QCs). We measured the acceptance and use of the programme through access statistics.

RESULTS

The e-learning course "Joint Prevention of Long-Term Ventilation" consists of 7 separate modules with practice-oriented training units as well as a cross-module area and corresponding interactive case studies. Users can receive 23 CME (continuing medical education) credits. The platform was released on July 1, 2021. By June 28, 2023, 214 users from 33 clinics had registered. Most users (77-98%) completed the modules, thus performing well in the test, where 90-100% passed. In the QCs, the users commended the structure and practical relevance of the programme, as well as the opportunity to earn CME credits.

CONCLUSION

Especially for medical staff in intensive care units, where continuous training is often a challenge during shift work, e-learning is a useful supplement to existing medical training.

TRIAL REGISTRATION

The PRiVENT study is registered at ClinicalTrials.gov (NCT05260853) on 02/03/2022.

Spontaneous breathing trial with pressure support on positive end-expiratory pressure and extensive use of non-invasive ventilation versus T-piece in difficult-to-wean patients from mechanical ventilation: a randomized controlled trial

BACKGROUND

The aim of this study is to assess whether a strategy combining spontaneous breathing trial (SBT) with both pressure support (PS) and positive end-expiratory pressure (PEEP) and extended use of post-extubation non-invasive ventilation (NIV) (extensively-assisted weaning) would shorten the time until successful extubation as compared with SBT with T-piece (TP) and post-extubation NIV performed in selected patients as advocated by guidelines (standard weaning), in difficult-to-wean patients from mechanical ventilation.

METHODS

The study is a single-center prospective open label, randomized controlled superiority trial with two parallel groups and balanced randomization with a 1:1 ratio. Eligible patients were intubated patients mechanically ventilated for more than 24 h who failed their first SBT using TP. In the extensively-assisted weaning group, SBT was performed with PS (7 cmH2O) and PEEP (5 cmH2O). In case of SBT success, an additional SBT with TP was performed. Failure of this SBT-TP was an additional criterion for post-extubation NIV in this group in addition to other recommended criteria. In the standard weaning group, SBT was performed with TP, and NIV was performed according to international guidelines. The primary outcome criterion was the time between inclusion and successful extubation evaluated with a Cox model with adjustment on randomization strata.

RESULTS

From May 2019 to March 2023, 98 patients were included and randomized in the study (49 in each group). Four patients were excluded from the intention-to-treat population (2 in both groups); therefore, 47 patients were analyzed in each group. The extensively-assisted weaning group had a higher median age (68 [58-73] vs. 62 [55-71] yrs.) and similar sex ratio (62% male vs. 57%). Time until successful extubation was not significantly different between extensively-assisted and standard weaning groups (median, 172 [50-436] vs. 95 [47-232] hours, Cox hazard ratio for successful extubation, 0.88 [95% confidence interval: 0.55-1.42] using the standard weaning group as a reference; p = 0.60). All secondary outcomes were not significantly different between groups.

CONCLUSION

An extensively-assisted weaning strategy did not lead to a shorter time to successful extubation than a standard weaning strategy. Trial registration The trial was registered on ClinicalTrials.gov (NCT03861117), on March 1, 2019, before the inclusion of the first patient. https://clinicaltrials.gov/study/NCT03861117 .

Critical illness-associated limb and diaphragmatic weakness

PURPOSE OF REVIEW

In the current review, we aim to highlight the evolving evidence on the diagnosis, prevention and treatment of critical illness weakness (CIW) and critical illness associated diaphragmatic weakness (CIDW).

RECENT FINDINGS

In the ICU, several risk factors can lead to CIW and CIDW. Recent evidence suggests that they have different pathophysiological mechanisms and impact on outcomes, although they share common risk factors and may overlap in several patients. Their diagnosis is challenging, because CIW diagnosis is primarily clinical and, therefore, difficult to obtain in the ICU population, and CIDW diagnosis is complex and not easily performed at the bedside. All of these issues lead to underdiagnosis of CIW and CIDW, which significantly increases the risk of complications and the impact on both short and long term outcomes. Moreover, recent studies have explored promising diagnostic techniques that are may be easily implemented in daily clinical practice. In addition, this review summarizes the latest research aimed at improving how to prevent and treat CIW and CIDW.

SUMMARY

This review aims to clarify some uncertain aspects and provide helpful information on developing monitoring techniques and therapeutic interventions for managing CIW and CIDW.

Consistency of data reporting in fluid responsiveness studies in the critically ill setting: the CODEFIRE consensus from the Cardiovascular Dynamic section of the European Society of Intensive Care Medicine

PURPOSE

To provide consensus recommendations regarding hemodynamic data reporting in studies investigating fluid responsiveness and fluid challenge (FC) use in the intensive care unit (ICU).

METHODS

The Executive Committee of the European Society of Intensive Care Medicine (ESICM) commissioned and supervised the project. A panel of 18 international experts and a methodologist identified main domains and items from a systematic literature, plus 2 ancillary domains. A three-step Delphi process based on an iterative approach was used to obtain the final consensus. In the Delphi 1 and 2, the items were selected with strong (≥ 80% of votes) or week agreement (70-80% of votes), while the Delphi 3 generated recommended (≥ 90% of votes) or suggested (80-90% of votes) items (RI and SI, respectively).

RESULTS

We identified 5 main domains initially including 117 items and the consensus finally resulted in 52 recommendations or suggestions: 18 RIs and 2 SIs statements were obtained for the domain "ICU admission", 11 RIs and 1 SI for the domain "mechanical ventilation", 5 RIs for the domain "reason for giving a FC", 8 RIs for the domain pre- and post-FC "hemodynamic data", and 7 RIs for the domain "pre-FC infused drugs". We had no consensus on the use of echocardiography, strong agreement regarding the volume (4 ml/kg) and the reference variable (cardiac output), while weak on administration rate (within 10 min) of FC in this setting.

CONCLUSION

This consensus found 5 main domains and provided 52 recommendations for data reporting in studies investigating fluid responsiveness in ICU patients.

Acute Respiratory Failure in Severe Acute Brain Injury

Acute respiratory failure is commonly encountered in severe acute brain injury due to a multitude of factors related to the sequelae of the primary injury. The interaction between pulmonary and neurologic systems in this population is complex, often with competing priorities. Many treatment modalities for acute respiratory failure can result in deleterious effects on cerebral physiology, and secondary brain injury due to elevations in intracranial pressure or impaired cerebral perfusion. High-quality literature is lacking to guide clinical decision-making in this population, and deliberate considerations of individual patient factors must be considered to optimize each patient's care.

Prolonged Mechanical Ventilation, Weaning, and the Role of Tracheostomy

Depending on the definitional criteria used, approximately 5% to 10% of critical adults will require prolonged mechanical ventilation with longer-term outcomes that are worse than those ventilated for a shorter duration. Outcomes are affected by patient characteristics before critical illness and its severity but also by organizational characteristics and care models. Definitive trials of interventions to inform care activities, such as ventilator weaning, upper airway management, rehabilitation, and nutrition specific to the prolonged mechanical ventilation patient population, are lacking. A structured and individualized approach developed by the multiprofessional team in discussion with the patient and their family is warranted.

Ventilator Weaning in Prolonged Mechanical Ventilation-A Narrative Review

Patients requiring mechanical ventilation (MV) beyond 21 days, usually referred to as prolonged MV, represent a unique group with significant medical needs and a generally poor prognosis. Research suggests that approximately 10% of all MV patients will need prolonged ventilatory care, and that number will continue to rise. Although we have extensive knowledge of MV in the acute care setting, less is known about care in the post-ICU setting. More than 50% of patients who were deemed unweanable in the ICU will be liberated from MV in the post-acute setting. Prolonged MV also presents a challenge in care for medically complex, elderly, socioeconomically disadvantaged and marginalized individuals, usually at the end of their life. Patients and their families often rely on ventilator weaning facilities and skilled nursing homes for the continuation of care, but home ventilation is becoming more common. The focus of this review is to discuss recent advances in the weaning strategies in prolonged MV, present their outcomes and provide insight into the complexity of care.

ERS International Congress 2023: highlights from the Respiratory Intensive Care Assembly

Early career members of Assembly 2 (Respiratory Intensive Care) attended the 2023 European Respiratory Society International Congress in Milan, Italy. The conference covered acute and chronic respiratory failure. Sessions of interest to our assembly members and to those interested in respiratory critical care are summarised in this article and include the latest updates in respiratory intensive care, in particular acute respiratory distress syndrome and mechanical ventilation.

Role of multidrug-resistant bacteria in weaning from invasive mechanical ventilation

BACKGROUND

Although multidrug-resistant bacteria (MDR) are common in patients undergoing prolonged weaning, there is little data on their impact on weaning and patient outcomes.

METHODS

This is a retrospective analysis of consecutive patients who underwent prolonged weaning and were at a university weaning centre from January 2018 to December 2020. The influence of MDR colonisation and infection on weaning success (category 3a and 3b), successful prolonged weaning from invasive mechanical ventilation (IMV) with or without the need for non-invasive ventilation (NIV) compared with category 3c (weaning failure 3cI or death 3cII) was investigated. The pathogen groups considered were: multidrug-resistant gram-negative bacteria (MDRGN), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. (VRE).

RESULTS

A total of 206 patients were studied, of whom 91 (44.2%) showed evidence of MDR bacteria (32% VRE, 1.5% MRSA and 16% MDRGN), with 25 patients also meeting the criteria for MDR infection. 70.9% of the 206 patients were successfully weaned from IMV, 8.7% died. In 72.2% of cases, nosocomial pneumonia and other infections were the main cause of death. Patients with evidence of MDR (infection and colonisation) had a higher incidence of weaning failure than those without evidence of MDR (48% vs. 34.8% vs. 21.7%). In multivariate analyses, MDR infection (OR 4.9, p = 0.004) was an independent risk factor for weaning failure, along with male sex (OR 2.3, p = 0.025), Charlson Comorbidity Index (OR 1.2, p = 0.027), pH (OR 2.7, p < 0.001) and duration of IMV before admission (OR 1.01, p < 0.001). In addition, MDR infection was the only independent risk factor for death (category 3cII), (OR 6.66, p = 0.007).

CONCLUSION

Patients with MDR infection are significantly more likely to die during the weaning process. There is an urgent need to develop non-antibiotic approaches for the prevention and treatment of MDR infections as well as clinical research on antibiotic stewardship in prolonged weaning as well as in ICUs.

The influence of drugs used for sedation during mechanical ventilation on respiratory pattern during unassisted breathing and assisted mechanical ventilation: a physiological systematic review and meta-analysis

Background

Sedation management has a major impact on outcomes in mechanically ventilated patients, but sedation strategies do not generally consider the differential effects of different sedatives on respiration and respiratory pattern. A systematic review was undertaken to quantitatively summarize the known effects of different classes of drugs used for sedation on respiratory pattern during both spontaneous breathing and assisted mechanical ventilation.

Methods

This was a systematic review and meta-analysis conducted using Ovid MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials up to June 2020 to retrieve studies that measured respiratory parameters before and after the administration of opioids, benzodiazepines, intravenous and inhaled anaesthetic agents, and other hypnotic agents (PROSPERO #CRD42020190017). A random-effects meta-analytic model was employed to estimate the mean percentage change in each of the respiratory indices according to medication exposure with and without mechanical ventilation. Risk of bias was assessed using the Cochrane risk of bias assessment tools.

Findings

Fifty-one studies were included in the analysis. Risk of bias was generally deemed to be low for most studies. Respiratory rate decreased with the administration of opioids in both non-ventilated patients (18% decrease, 95% CI 12-24%) and ventilated patients (26% decrease, 95% CI 15-37%) and increased with inhaled anaesthetics in non-ventilated patients (83% increase, 95% CI 49-118%) and ventilated patients (50% increase, 28-72%). In non-ventilated patients, tidal volume decreased following administration of inhaled aesthetics (55% decrease, 95% CI 25-86%), propofol (36% decrease, 95% CI 20-52%), and benzodiazepines (28% decrease, 95% CI 17-40%); in patients receiving assisted mechanical ventilation, tidal volume was not significantly affected by sedation. Administration of other hypnotic agents was not associated with changes in respiratory rate or tidal volume.

Interpretation

Different classes of drugs used for sedation exert differential effects on respiratory pattern, and this may influence weaning and outcomes in mechanically ventilated patients.

Funding

This study did not receive any funding support.

Setting positive end-expiratory pressure: lung and diaphragm ultrasound

PURPOSE OF REVIEW

The purpose of this review is to summarize the role of lung ultrasound and diaphragm ultrasound in guiding ventilator settings with an emphasis on positive end-expiratory pressure (PEEP). Recent advances for using ultrasound to assess the effects of PEEP on the lungs and diaphragm are discussed.

RECENT FINDINGS

Lung ultrasound can accurately diagnose the cause of acute respiratory failure, including acute respiratory distress syndrome and can identify focal and nonfocal lung morphology in these patients. This is essential in determining optimal ventilator strategy and PEEP level. Assessment of the effect of PEEP on lung recruitment using lung ultrasound is promising, especially in the perioperative setting. Diaphragm ultrasound can monitor the effects of PEEP on the diaphragm, but this needs further validation. In patients with an acute exacerbation of chronic obstructive pulmonary disease, diaphragm ultrasound can be used to predict noninvasive ventilation failure. Lung and diaphragm ultrasound can be used to predict weaning outcome and accurately diagnose the cause of weaning failure.

SUMMARY

Lung and diaphragm ultrasound are useful for diagnosing the cause of respiratory failure and subsequently setting the ventilator including PEEP. Effects of PEEP on lung and diaphragm can be monitored using ultrasound.

Effect of aggressive vs conservative screening and confirmatory test on time to extubation among patients at low or intermediate risk: a randomized clinical trial

PURPOSE

This study aimed to determine the best strategy to achieve fast and safe extubation.

METHODS

This multicenter trial randomized patients with primary respiratory failure and low-to-intermediate risk for extubation failure with planned high-flow nasal cannula (HFNC) preventive therapy. It included four groups: (1) conservative screening with ratio of partial pressure of arterial oxygen (PaO2) to fraction of inspired oxygen (FiO2) ≥ 150 and positive end-expiratory pressure (PEEP) ≤ 8 cmH2O plus conservative spontaneous breathing trial (SBT) with pressure support 5 cmH2O + PEEP 0 cmH2O); (2) screening with ratio of partial pressure of arterial oxygen (PaO2) to fraction of inspired oxygen (FiO2) ≥ 150 and PEEP ≤ 8 plus aggressive SBT with pressure support 8 + PEEP 5; (3) aggressive screening with PaO2/FiO2 > 180 and PEEP 10 maintained until the SBT with pressure support 8 + PEEP 5; (4) screening with PaO2/FiO2 > 180 and PEEP 10 maintained until the SBT with pressure support 5 + PEEP 0. Primary outcomes were time-to-extubation and simple weaning rate. Secondary outcomes included reintubation within 7 days after extubation.

RESULTS

Randomization to the aggressive-aggressive group was discontinued at the interim analysis for safety reasons. Thus, 884 patients who underwent at least 1 SBT were analyzed (conservative-conservative group, n = 256; conservative-aggressive group, n = 267; aggressive-conservative group, n = 261; aggressive-aggressive, n = 100). Median time to extubation was lower in the groups with aggressive screening (p < 0.001). Simple weaning rates were 45.7%, 76.78% (205 patients), 71.65%, and 91% (p < 0.001), respectively. Reintubation rates did not differ significantly (p = 0.431).

CONCLUSION

Among patients at low or intermediate risk for extubation failure with planned HFNC, combining aggressive screening with preventive PEEP and a conservative SBT reduced the time to extubation without increasing the reintubation rate.

Risk factors for long-term invasive mechanical ventilation: a longitudinal study using German health claims data

BACKGROUND

Long-term invasive mechanical ventilation (IMV) is a major burden for those affected and causes high costs for the health care system. Early risk assessment is a prerequisite for the best possible support of high-risk patients during the weaning process. We aimed to identify risk factors for long-term IMV within 96 h (h) after the onset of IMV.

METHODS

The analysis was based on data from one of Germany's largest statutory health insurance funds; patients who received IMV ≥ 96 h and were admitted in January 2015 at the earliest and discharged in December 2017 at the latest were analysed. OPS and ICD codes of IMV patients were considered, including the 365 days before intubation and 30 days after discharge. Long-term IMV was defined as evidence of invasive home mechanical ventilation (HMV), IMV ≥ 500 h, or readmission with (re)prolonged ventilation.

RESULTS

In the analysis of 7758 hospitalisations, criteria for long-term IMV were met in 38.3% of cases, of which 13.9% had evidence of HMV, 73.1% received IMV ≥ 500 h and/or 40.3% were re-hospitalised with IMV. Several independent risk factors were identified (p < 0.005 each), including pre-diagnoses such as pneumothorax (OR 2.10), acute pancreatitis (OR 2.64), eating disorders (OR 1.99) or rheumatic mitral valve disease (OR 1.89). Among ICU admissions, previous dependence on an aspirator or respirator (OR 5.13), and previous tracheostomy (OR 2.17) were particularly important, while neurosurgery (OR 2.61), early tracheostomy (OR 3.97) and treatment for severe respiratory failure such as positioning treatment (OR 2.31) and extracorporeal lung support (OR 1.80) were relevant procedures in the first 96 h after intubation.

CONCLUSION

This comprehensive analysis of health claims has identified several risk factors for the risk of long-term ventilation. In addition to the known clinical risks, the information obtained may help to identify patients at risk at an early stage. Trial registration The PRiVENT study was retrospectively registered at ClinicalTrials.gov (NCT05260853). Registered at March 2, 2022.

Diaphragm Dysfunction Predicts Weaning Outcome after Bilateral Lung Transplant

BACKGROUND

Diaphragm dysfunction and its effects on outcomes of ventilator weaning have been evaluated in mixed critical care populations using diaphragm thickening fraction (the ratio of the difference between ultrasound diaphragm thickness at end-inspiration and end-expiration to diaphragm thickness at end-expiration) or neuroventilatory efficiency (the ratio of tidal volume and peak electrical activity of the diaphragm). Such data are not available in bilateral-lung transplant recipients. The authors hypothesized that (1) diaphragm dysfunction, as defined by a diaphragm thickening fraction less than 29%, is more likely to occur in difficult weaning; (2) diaphragm thickening fraction and neuroventilatory efficiency predict weaning outcome; and (3) duration of mechanical ventilation before the first spontaneous breathing trial is associated with diaphragm dysfunction.

METHODS

Adult bilateral-lung transplant patients admitted to the intensive care unit were screened at the time of the first spontaneous breathing trial (pressure-support of 5 cm H2O and 0 positive end-expiratory pressure). At the fifth minute, diaphragm thickening fraction and neuroventilatory efficiency were measured during three respiratory cycles. Weaning was classified as simple, difficult, or prolonged (successful extubation at the first spontaneous breathing trial, within three or after three spontaneous breathing trials, respectively).

RESULTS

Forty-four subjects were enrolled. Diaphragm dysfunction occurred in 14 subjects (32%), all of whom had difficult weaning (78% of the subgroup of 18 patients experiencing difficult weaning). Both diaphragm thickening fraction (24 [20 to 29] vs. 39 [35 to 45]%) and neuroventilatory efficiency (34 [26 to 45] vs. 55 [43 to 62] ml/µV) were lower in difficult weaning (both P < 0.001). The areas under the receiver operator curve predicting difficult weaning were 0.88 (95% CI, 0.73 to 0.99) for diaphragm thickening fraction and 0.85 (95% CI, 0.71 to 0.95) for neuroventilatory efficiency. The duration of ventilation demonstrated a linear inverse correlation with both diaphragm thickening fraction and neuroventilatory efficiency.

CONCLUSIONS

Diaphragm dysfunction is common after bilateral-lung transplantation and associated with difficult weaning. In such patients, average values for diaphragm thickening fraction and neuroventilatory efficiency were reduced compared to patients with simple weaning. Both parameters showed similar accuracy for predicting success of ventilator weaning, demonstrating an inverse relationship with duration of ventilation.

EDITOR’S PERSPECTIVE

Weaning and extubation failure in myasthenic crisis: a multicenter analysis

Myasthenic crisis (MC) requiring mechanical ventilation is a serious complication of myasthenia gravis (MG). Here we analyze the frequency and risk factors of weaning- and extubation failure as well as its impact on the clinical course in a large cohort. We performed a retrospective chart review on patients treated for MC in 12 German neurological departments between 2006 and 2015. Weaning failure (WF) was defined as negative spontaneous breathing trial, primary tracheostomy, or extubation failure (EF) (reintubation or death). WF occurred in 138 episodes (64.2%). Older Age (p = 0.039), multiple comorbidities (≥ 3) (p = 0.007, OR = 4.04), late-onset MG (p = 0.004, OR = 2.84), complications like atelectasis (p = 0.008, OR = 3.40), pneumonia (p < 0.0001, OR = 3.45), cardio-pulmonary resuscitation (p = 0.005, OR = 5.00) and sepsis (p = 0.02, OR = 2.57) were associated with WF. WF occurred often in patients treated with intravenous immungloblins (IVIG) (p = 0.002, OR = 2.53), whereas WF was less often under first-line therapy with plasma exchange or immunoadsorption (p = 0.07, OR = 0.57). EF was observed in 58 of 135 episodes (43.0%) after first extubation attempt and was related with prolonged mechanical ventilation, intensive care unit stay and hospital stay (p ≤ 0.0001 for all). Extubation success was most likely in a time window for extubation between day 7 and 12 after intubation (p = 0.06, OR = 2.12). We conclude that WF and EF occur very often in MC and are associated with poor outcome. Older age, multiple comorbidities and development of cardiac and pulmonary complications are associated with a higher risk of WF and EF. Our data suggest that WF occurs less frequently under first-line plasma exchange/immunoadsorption compared with first-line use of IVIG.

Sex difference in the risk of extubation failure in ICUs

BACKGROUND

Little attention has been paid to potential differences in prognosis between mechanically ventilated males and females in intensive care units (ICUs). We hypothesized that a sex gap in the risk of extubation failure in ICUs may exist.

METHODS

Post hoc analysis of a large-scale clinical trial including patients at high risk of extubation failure in ICUs, with the aim of assessing the risk of extubation failure according to sex. The primary outcome was reintubation within the 7 days following extubation.

RESULTS

Out of 641 patients, 425 (66%) were males and 216 (34%) were females. Males were more likely to be admitted for cardiac arrest and to have underlying ischemic heart disease whereas females were more likely to be admitted for coma and to have obesity. Whereas the rate of reintubation at 48 h was significantly higher in males than in females (11.0% vs. 6.0%; difference, + 5.0 [95% CI, 0.2 to 9.2]; P = 0.038), the rate of reintubation at day 7 did not significantly differ between males and females (16.7% vs. 11.1%; difference, + 5.6% [95%CI, - 0.3 to 10.8], P = 0.059). Using multivariable logistic regression analysis, male sex was independently associated with reintubation within the 7 days following extubation (adjusted OR 1.70 [95% CI, 1.01 to 2.89]; P = 0.048), even after adjustment on reason for admission, body-mass index, severity score, respiratory rate before extubation, and noninvasive ventilation after extubation.

CONCLUSION

In this post hoc analysis of a clinical trial including a homogeneous subset of patients at high risk of extubation failure, sex was independently associated with reintubation. The role of sex on outcomes should be systematically examined in future studies of critically ill patients.

Liberation From Venovenous Extracorporeal Membrane Oxygenation for Respiratory Failure: A Scoping Review

BACKGROUND

Safe and timely liberation from venovenous extracorporeal membrane oxygenation (ECMO) would be expected to reduce the duration of ECMO, the risk of complications, and costs. However, how to liberate patients from venovenous ECMO effectively remains understudied.

RESEARCH QUESTION

What is the current state of the evidence on liberation from venovenous ECMO?

STUDY DESIGN AND METHODS

We systematically searched for relevant publications on liberation from venovenous ECMO in Medline and EMBASE. Citations were included if the manuscripts provided any of the following: criteria for readiness for liberation, a liberation protocol, or a definition of successful decannulation or decannulation failure. We included randomized trials, observational trials, narrative reviews, guidelines, editorials, and commentaries. We excluded single case reports and citations where the full text was unavailable.

RESULTS

We screened 1,467 citations to identify 39 key publications on liberation from venovenous ECMO. We then summarized the data into five main topics: current strategies used for liberation, criteria used to define readiness for liberation, conducting liberation trials, criteria used to proceed with decannulation, and parameters used to predict decannulation outcomes.

INTERPRETATION

Practices on liberation from venovenous ECMO are heterogeneous and are influenced strongly by clinician preference. Additional research on liberation thresholds is needed to define optimal liberation strategies and to close existing knowledge gaps in essential topics on liberation from venovenous ECMO.

Utilization of spontaneous breathing trial, objective cough test, and diaphragmatic ultrasound results to predict extubation success: COBRE-US trial

BACKGROUND

The results of clinical and weaning readiness tests and the spontaneous breathing trial (SBT) are used to predict the success of the weaning process and extubation.

METHODS

We evaluated the capacity of the cuff leak test, rate of rapid and shallow breathing, cough intensity, and diaphragmatic contraction velocity (DCV) to predict the success of the SBT and extubation in a prospective, multicenter observational study with consecutive adult patients admitted to four intensive care units. We used receiver operating characteristic (ROC) curves to assess the tests' predictive capacity and built predictive models using logistic regression.

RESULTS

We recruited 367 subjects who were receiving invasive mechanical ventilation and on whom 456 SBTs were performed, with a success rate of 76.5%. To predict the success of the SBT, we derived the following equation: (0.56 × Cough) - (0.13 × DCV) + 0.25. When the cutoff point was ≥ 0.83, the sensitivity was 91.5%, the specificity was 22.1%, and the overall accuracy was 76.2%. The area under the ROC curve (AUC-ROC) was 0.63. To predict extubation success, we derived the following equation: (5.7 × SBT) + (0.75 × Cough) - (0.25 × DCV) - 4.5. When the cutoff point was ≥ 1.25, the sensitivity was 96.8%, the specificity was 78.4%, and the overall accuracy was 91.5%. The AUC-ROC of this model was 0.91.

CONCLUSION

Objective measurement of cough and diaphragmatic contraction velocity could be used to predict SBT success. The equation for predicting successful extubation, which includes SBT, cough, and diaphragmatic contraction velocity values, showed excellent discriminative capacity.

Wean to Win

How to cite this article: Havaldar AA, Krishna B. Wean to Win. Indian J Crit Care Med 2023;27(10):695-696.

Mechanical Power Density Predicts Prolonged Ventilation Following Double Lung Transplantation

Prolonged mechanical ventilation (PMV) after lung transplantation poses several risks, including higher tracheostomy rates and increased in-hospital mortality. Mechanical power (MP) of artificial ventilation unifies the ventilatory variables that determine gas exchange and may be related to allograft function following transplant, affecting ventilator weaning. We retrospectively analyzed consecutive double lung transplant recipients at a national transplant center, ventilated through endotracheal tubes upon ICU admission, excluding those receiving extracorporeal support. MP and derived indexes assessed up to 36 h after transplant were correlated with invasive ventilation duration using Spearman's coefficient, and we conducted receiver operating characteristic (ROC) curve analysis to evaluate the accuracy in predicting PMV (>72 h), expressed as area under the ROC curve (AUROC). PMV occurred in 82 (35%) out of 237 cases. MP was significantly correlated with invasive ventilation duration (Spearman's ρ = 0.252 [95% CI 0.129-0.369], p < 0.01), with power density (MP normalized to lung-thorax compliance) demonstrating the strongest correlation (ρ = 0.452 [0.345-0.548], p < 0.01) and enhancing PMV prediction (AUROC 0.78 [95% CI 0.72-0.83], p < 0.01) compared to MP (AUROC 0.66 [0.60-0.72], p < 0.01). Mechanical power density may help identify patients at risk for PMV after double lung transplantation.

Costs of Weaning Failure: A Prospective, Multicentre, Controlled, Non-Randomised, Interventional Study on Economic Implications for the German Health Care System

BACKGROUND

Intensive care patients with respiratory failure often need invasive mechanical ventilation (IMV). With increasing population age and multimorbidity, the number of patients who cannot be weaned from IMV rises as well. Up to 85% of these patients have no access to a certified weaning centre. Their medical care is associated with impaired quality of life and high costs for the German health care system.

OBJECTIVES

This study examined the weaning outcome of patients in certified weaning centres after a primarily unsuccessful weaning attempt in order to calculate saving expenses compared to patients on long-term IMV in an outpatient setting.

METHODS

In this multicentre, controlled, non-randomised, interventional, prospective study, 61 patients (16 from out-of-hospital long-term IMV, 49 from other hospitals) were referred to a certified weaning centre for a second weaning phase. The incurred costs after 1 year of the latter were compared to insurance claim data of patients who were discharged from an acute hospital stay to receive IMV in an outpatient setting.

RESULTS

In the intervention group, 50 patients (82%) could be completely weaned or partially weaned using non-invasive ventilation, thus not needing IMV any longer. The costs per patient for weaning and out-of-hospital care in the intervention group were EUR 114,877.08, and the costs in the comparison cohort were EUR 234,442.62.

CONCLUSIONS

Early transfer to a certified weaning centre can increase weaning success and reduce total costs by approximately EUR 120,000 per patient in the first year. Given the existing structural prerequisites in Germany, every patient should have access to a weaning centre before being transferred to long-term IMV, from a medical and health economical point of view.

New insights into acute and chronic respiratory failure: highlights from the Respiratory Failure and Mechanical Ventilation Conference 2022

The European Respiratory Society (ERS) is home to clinicians, scientists and students interested in respiratory medicine. In June 2022, the Society organised the second edition of the “Respiratory Failure and Mechanical Ventilation Conference”. This event focuses on clinical and scientific aspects of acute and chronic respiratory failure. Faculty and participants from 50 countries around the globe met in Berlin, although this time most of the sessions could also be accessed online. Participants with very diverse backgrounds, including medicine, nursing, physiotherapy and industry, discussed all aspects of respiratory failure including physiology, interventions for respiratory support, advanced diagnostic techniques, quality of life, and end of life care. Our common ground was passion for respiratory failure. The quality of the sessions during this 3-day conference was outstanding, and many of the presentations are still available for conference participants through the ERS website. However, the conference organisers felt that many of the topics discussed deserved an even broader audience.

Highlights from the Respiratory Failure and Mechanical Ventilation Conference 2022 https://bit.ly/3HMWKTp

Brain-lung crosstalk: how should we manage the breathing brain?

Recent studies have drawn increasing attention to brain-lung crosstalk in critically ill patients. However, further research is needed to investigate the pathophysiological interactions between the brain and lungs, establish neuroprotective ventilatory strategies for brain-injured patients, provide guidance on potentially conflicting treatment priorities in patients with concomitant brain and lung injury, and enhance prognostic models to inform extubation and tracheostomy decisions. To bring together such research, BMC Pulmonary Medicine welcomes submissions to its new Collection on 'Brain-lung crosstalk'.

Treatment with levosimendan in an experimental model of early ventilator-induced diaphragmatic dysfunction

Introduction

Mechanical ventilation (MV) is a life-saving approach in critically ill patients. However, it may affect the diaphragmatic structure and function, beyond the lungs. Levosimendan is a calcium sensitizer widely used in clinics to improve cardiac contractility in acute heart failure patients. In vitro studies have demonstrated that levosimendan increased force-generating capacity of the diaphragm in chronic obstructive pulmonary disease patients. Thus the aim of this study was to evaluate the effects of levosimendan administration in an animal model of ventilator-induced diaphragmatic dysfunction (VIDD) on muscle contraction and diaphragm muscle cell viability.

Methods

Sprague-Dawley rats underwent prolonged MV (5 hours). VIDD+Levo group received a starting bolus of levosimendan immediately after intratracheal intubation and then an intravenous infusion of levosimendan throughout the study. Diaphragms were collected for ex vivo contractility measurement (with electric stimulation), histological analysis and Western blot analysis. Healthy rats were used as the control.

Results

Levosimendan treatment maintained an adequate mean arterial pressure during the entire experimental protocol, preserved levels of autophagy-related proteins (LC3BI and LC3BII) and the muscular cell diameter demonstrated by histological analysis. Levosimendan did not affect the diaphragmatic contraction or the levels of proteins involved in the protein degradation (atrogin).

Conclusions

Our data suggest that levosimendan preserves muscular cell structure (cross-sectional area) and muscle autophagy after 5 hours of MV in a rat model of VIDD. However, levosimendan did not improve diaphragm contractile efficiency.