Prolonged Weaning Research Articles

A multidimensional approach to the management of patients in prolonged weaning from mechanical ventilation - the concept of treatable traits - a narrative review.

Background Established structured weaning approaches, which are effective for patients in simple and difficult weaning, are often not appropriate for patients undergoing prolonged weaning. Addressing the complexity of weaning failure requires personalized precision medicine. The therapeutic concept of Treatable Traits (TTs) has been proposed as a new paradigm for the management of chronic respiratory diseases. It is based on a multidimensional assessment of specific characteristics, which can be addressed by specific interventions that go beyond traditional diagnostic criteria. The concept is increasingly adopted for other complex diseases. Summary This is a narrative review and an expert opinion on the development of a concept of TTs for patients undergoing prolonged weaning. The proposed TTs are based on a systematic review of risk factors for prolonged weaning, an analysis of claims data to assess risk factors within 96 hours of IMV onset and data from the WEAN-SAFE study. A multidisciplinary team identified clinically important TTs and determined appropriate interventions. The following TTs have been identified: Airway disorders and complications associated with tracheostomy or intubation, such as airway obstruction, strictures or tracheomalacia, infectious aspects, anxiety, depression, delirium, post-traumatic stress disorder, anemia, pulmonary and cardio-renal disease. The multidimensional holistic approach also includes tailored sedation and pain management, nutritional therapy, early mobilization and physiotherapy. Key message We propose a framework of relevant considerations for a multidimensional approach to the management of patients undergoing prolonged weaning that supports the regain of respiratory capacity, reduces the respiratory load and thus could resolve the respiratory workload imbalance.

Impact of sleep disturbances on outcomes in intensive care units

BackgroundSleep deprivation is common in intensive care units (ICUs) and may alter respiratory performance. Few studies have assessed the role of sleep disturbances on outcomes in critically ill patients.ObjectivesWe hypothesized that sleep disturbances may be associated with poor outcomes in ICUs.MethodsPost-hoc analysis pooling three observational studies assessing sleep by complete polysomnography in 131 conscious and non-sedated patients included at different times of their ICU stay. Sleep was assessed early in a group of patients admitted for acute respiratory failure while breathing spontaneously (n = 34), or under mechanical ventilation in patients with weaning difficulties (n = 45), or immediately after extubation (n = 52). Patients admitted for acute respiratory failure who required intubation, those under mechanical ventilation who had prolonged weaning, and those who required reintubation after extubation were considered as having poor clinical outcomes. Durations of deep sleep, rapid eye movement (REM) sleep, and atypical sleep were compared according to the timing of polysomnography and the clinical outcomes.ResultsWhereas deep sleep remained preserved in patients admitted for acute respiratory failure, it was markedly reduced under mechanical ventilation and after extubation (p < 0.01). Atypical sleep was significantly more frequent in patients under mechanical ventilation than in those breathing spontaneously (p < 0.01). REM sleep was uncommon at any time of their ICU stay. Patients with complete disappearance of REM sleep (50% of patients) were more likely to have poor clinical outcomes than those with persistent REM sleep (24% vs. 9%, p = 0.03).ConclusionComplete disappearance of REM sleep was significantly associated with poor clinical outcomes in critically ill patients.

Differences between women and men in prolonged weaning

BackgroundIn recent years, the importance of sex as a factor influencing medical care has received increasing attention in the field of intensive care medicine. The objective of this study was to examine the influence of sex in prolonged weaning.MethodsA retrospective analysis of patients undergoing prolonged weaning at Thoraxklinik, University Hospital Heidelberg between 12/08 and 12/23 was conducted. Patients with neuromuscular diseases were excluded from the analyses. The risk factors for weaning failure in men and women were identified through stepwise cox-regression analyses.ResultsA total of 785 patients were included, of whom 313 (39.9%) were women. 77.9% of the women and 75.4% of the men were successfully weaned from invasive ventilation. In group comparisons and multivariable analyses, sex was not found to be a risk factor for weaning failure. Cox regression analyses were performed separately for both sexes on the outcome of weaning failure, adjusting for relevant covariates. The results indicated that age ≥ 65 years (HR 2.38, p < 0.001) and the duration of IMV before transfer to the weaning centre (HR 1.01/day, p < 0.001) were independent risk factors in men. In women, however, the duration of IMV before transfer (HR 1.01, p < 0.001), previous non-invasive ventilation (HR 2.9, p 0.005), the presence of critical illness polyneuropathy (HR 1.82; p = 0.040) and delirium (HR 2.50, p = 0.017) were identified as relevant risk factors. In contrast delirium was associated with a favourable weaning outcome in men (HR 0.38, p = 0.020) and nosocomial pneumonia as a reason for prolonged weaning in women (HR 0.43; p = 0.032).ConclusionThe analyses indicate that there are sex-based differences in the risk factors associated with weaning failure. Further studies, ideally prospective, should confirm these findings to assess whether sex is a factor that should be taken into account to improve weaning outcomes.

Accelerated Wean: A Novel 3 Day Berlin Heart Protocol in a Pediatric Patient.

We present the case of a 4 year old child who developed cardiogenic shock due to permanent junctional reciprocating tachycardia, requiring left ventricular assist device (LVAD) support. Despite the initial critical clinical presentation, successful myocardial recovery was achieved over 5 months, allowing for successful LVAD explantation. The patient's young age and behavioral issues were constraining factors for a prolonged LVAD wean trial. A modified wean protocol over a 3 day period with parameters for assessment of cardiac recovery before LVAD explantation is described.

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.

Prolonged weaning after long-term ventilation due to SARS-CoV-2 infection: a multicenter retrospective analysis

Patients (n=751) with prolonged weaning (reason for ventilation "pneumonia" and "acute respiratory failure") from four centers for the period 2011-23 from the "WeanNet" registry were used as a matched group. The median duration of intensive medical care was 39 (25-68) days. In 19% (37/193) of patients, ECMO support was necessary for a median of 27 (18-51) days. In-hospital mortality was 8.3% (2.7% with vs. 9.6% without ECMO) and 6.8% died in the comparison group. At discharge, 84% (vs. 77% in the control group) were completely weaned and 2.6% (vs. 17.6% in the control group) of patients received non-invasive treatment. Invasive ventilation was still necessary in 7.8% (control group 15.7%). In the observation period of 6 months after discharge, 22.4% of patients required inpatient care and a further 14.1% after 12 months. The overall mortality at 12-month follow-up was 20,6% (5.6% with vs. 24.6% without ECMO). The mortality rate of ventilated patients with COVID-19 was very low at 8.3% in the four weaning centers studied. The mortality rate of patients with ECMO treatment was only 2.7%. The mortality rate in the control group was 7.3%. The lower mortality of patients with ECMO treatment was also evident at follow-up of up to 12 months.Patients with prolonged weaning who received invasive ventilation due to COVID-19 showed comparable results in terms of successful weaning and mortality compared to a control group from the WeanNet registry. The long-term results with a survival of more than 80% for the first year after discharge were encouraging.

Long-term health-related quality of life of patients after prolonged weaning depending on weaning status

Long-term outcome in patients with prolonged weaning is known to be impaired, particularly against the background of their weaning status; however, data on their health-related quality of life (HRQL) are sparse. HRQL was measured in patients with prolonged weaning using the Severe Respiratory Insufficiency Questionnaire (SRI). Overall, 39 out of 83 patients with prolonged weaning filled in the SRI questionnaire. The median interval between discharge from hospital and HRQL assessment was 3.5 years (IQR 2.4-4.5 years). In the total group, the median SRI summary score was 56.4 (IQR 38.8-73.5). Patients with unsuccessful weaning and subsequent invasive home mechanical ventilation (N=15) had worse HRQL as estimated from the SRI summary score when compared to those with successful weaning both without (n=13) and with subsequent long-term non-invasive ventilation (NIV) (n=11); Kruskal-Wallis-Test: H (2, n=39) = 7,875446; P=0.0195. Statistically significant differences indicating worse HRQL in patients with invasive home mechanical ventilation were particularly evident in the following SRI subscales: Social relationships (P=0.0325), Anxiety (P=0.0096), and Psychological well-being (P=0.0079). HRQL is substantially impaired in patients with unsuccessful prolonged weaning and subsequent invasive home mechanical ventilation compared to those with successful prolonged weaning. Further studies incorporating higher case numbers are needed to assess other conditions potentially affecting HRQL in patients with prolonged weaning.

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.

The therapeutic effect of levosimendan in patients with prolonged ventilator weaning and cardiac dysfunction.

To explore the therapeutic effect of levosimendan in patients with prolonged ventilator weaning and cardiac dysfunction. Patients with prolonged ventilator weaning and cardiac dysfunction were randomly allocated to receive conventional treatment (control group) or intravenous infusion of levosimendan for 24 h based on conventional treatment (levosimendan group). Weaning success rates were then compared between the two groups. The study was retrospectively registered with Research Registry (ID No. researchregistry10304). A total of 40 patients were included (20 per group). Within 3 days after initiation of treatment, significantly more cases were successfully weaned in the levosimendan group versus control group (eight versus four cases, respectively). Among the eight patients who underwent pulse indicator continuous cardiac output monitoring in the levosimendan group, the global ejection fraction increased 24 h after treatment, and the cardiac function index and cardiac index increased 72 h after treatment. For patients requiring prolonged mechanical ventilation who have concomitant cardiac dysfunction, levosimendan may be considered to increase the probability of weaning success.

Invasive Beatmung und prolongiertes Weaning: Auswirkungen osteopathischer Techniksequenzen

Mechanical ventilation is used as a life-sustaining tool in case of severe respiratory insufficiency. Weaning from the respiratory support is included in the process and the ability to breathe spontaneously independently. Prolonged weaning is the most difficult procedure. This process involves medical side effects, which should be counteracted by means of osteopathic approaches. For the evaluation of osteopathic influences in weaning, single-case studies in mixed method design were caried out. Osteopathic treatments were performed based on defined sequences of techniques. Quantitative data collection of medical measurement parameters was carried out in pre-post design. These were supplemented by standardized questionnaires regarding the patient's condition, as well as guided interviews. The results showed a supportive influence of osteopathic treatment on the weaning process.

Growing sabers: Mandibular shape and biomechanical performance trajectories during the ontogeny of Smilodon fatalis.

The evolution of organisms can be studied through the lens of developmental systems, as the timing of development of morphological features is an important aspect to consider when studying a phenotype. Such data can be challenging to obtain in fossil amniotes owing to the scarcity of their fossil record. However, the numerous remains of Rancho La Brea allow a detailed study of the postnatal changes in an extinct sabertoothed felid: Smilodon fatalis. Despite numerous previous studies on the ontogeny of Smilodon, an important question remained open: how did the cubs of Smilodon acquire and process food? By applying 3D geometric morphometrics and finite element analyses to 49 mandibles at various developmental stages (22 of S. fatalis, 23 of Panthera leo, and 4 of early diverging felids), we assess the changes in mandibular shape and performance during growth. Both lions and sabertooths exhibit a shift in mandibular shape, aligning with eruption of the lower carnassial. This marks the end of weaning in lions and suggests a prolonged weaning period in S. fatalis owing to its delayed eruption sequence. We also highlight distinct ontogenetic trajectories, with S. fatalis undergoing more postnatal mandibular shape changes. Finally, although S. fatalis appears more efficient than P. leo at performing an anchor bite, this efficiency is acquired through ontogeny and at a quite late age. The delayed shape change compared with P. leo and the low biting efficiency during the growth in Smilodon could indicate an extended duration of the parental care compared with P. leo.

Diaphragm ultrasound in patients with prolonged weaning from mechanical ventilation.

Several publications have examined diaphragmatic ultrasound using two-dimensional (2D) parameters in the context of weaning from mechanical ventilation (MV) and extubation. However, the studied cohorts had rather short duration of ventilation. Examinations on patients with prolonged weaning after long-term ventilation were missing. It was the aim of this study to assess of the diaphragm and peripheral musculature of patients undergoing prolonged weaning creating a chronological sequence of ultrasonic parameters during the course of weaning. This study was carried out as a monocentric, prospective observational cross-sectional study. Patients in prolonged weaning who were transferred to a specialized weaning unit were eligible for inclusion if they were ventilated invasively by means of an endotracheal tube or tracheal cannula and if their expected treatment period was at least 5 days. Diaphragmatic function and one representative peripheral muscle were examined in 50 patients between March 2020 and April 2021. The 2D sonographic parameters of diaphragm and diaphragmatic function consisted of diaphragmatic thickness (Tdi) at the end of inspiration and expiration, the fractional thickening (FT) and the diaphragmatic excursion. Additionally, the M. quadriceps femoris was sonographically assessed at two locations. The difference of measurements between the first and the last measuring timepoint were examined using the Wilcoxon signed-rank test. For a longer chronological sequence, the Friedman's rank sum test with subsequent Wilcoxon-Nemenyi-McDonald-Thompson test for multiple comparisons was carried out. Fifty patients with prolonged weaning were included. The median duration of MV before transfer to the weaning unit was 11.5 [interquartile range (IQR) 10] days. Forty-one patients could be assessed over the full course of weaning, with 38 successfully weaned. Within these 41 patients, the sonographic parameters of the diaphragm slightly increased over the course of weaning indicating an increase in thickness and mobility. Especially parameters which represented an active movement reached statistical significance, i.e., inspiratory Tdi when assessed under spontaneous breathing [begin 3.41 (0.99) vs. end 3.43 (1.31) mm; P=0.01] and diaphragmatic excursion [begin 0.7 (0.8) vs. end 0.9 (0.6) cm; P=0.01]. The presence of positive end-expiratory pressure (PEEP) and pressure support did not influence the sonographic parameters significantly. The M. quadriceps femoris, in contrast, decreased slightly but constantly over the time [lower third: begin 1.36 (0.48) vs. end 1.28 (0.36) cm; P=0.054]. The present study is the first one to longitudinally analyse diaphragmatic ultrasound in patients with prolonged weaning. Sonographic assessment showed that Tdi and excursion increased over the course of prolonged weaning, while the diameter of a representative peripheral muscle decreased. However, the changes are rather small, and data show a wide dispersion. To allow a potential, standardized use of diaphragm ultrasound for diagnostic decision support in prolonged weaning, further studies in this specific patient group are required.

Guillain-Barré syndrome after surgery: a literature review.

Guillain-Barré syndrome (GBS) is a rare postoperative complication that is sometimes characterized by serious motor weakness and prolonged weaning from mechanical ventilation. Although the exact nature of the relationship between GBS and the surgical procedure is still unclear, there is a clear increased incidence of GBS in post-surgical patients compared to non-surgical patients. GBS after surgery is unique in several ways. The course of post-surgical GBS unfolds more rapidly than in other situations where GBS develops, the condition is often more severe, and respiratory muscles are more commonly involved. Prompt diagnosis and appropriate treatment are essential, and the condition can worsen if treated inappropriately. Postoperative sedation, intubation, and restraint use make the diagnosis of GBS difficult, as the onset of symptoms of weakness or numbness in those contexts are not obvious. GBS is often misdiagnosed, being attributed to other postoperative complications, and subsequently mishandled. The lack of relevant information further obscures the clinical picture. We sought to better understand post-surgical GBS by performing an analysis of the relevant literature, focusing on clearly documenting the clinical characteristics, diagnosis, and management of GBS that emerges following surgery. We underscore the importance of physicians being aware of the possibility of GBS after major surgery and of performing a variety of laboratory clinical investigations early on in suspected cases.

Effects of structured protocolized physical therapy on the duration of mechanical ventilation in patients with prolonged weaning

Purpose20% of patients with mechanical ventilation (MV) have a prolonged, complex weaning process, often experiencing a condition of ICU-acquired weakness (ICUAW), with a severe decrease in muscle function and restricted long-term prognosis. We aimed to analyze a protocolized, systematic approach of physiotherapy in prolonged weaning patients and hypothesized that the duration of weaning from MV would be shortened. MethodsICU patients with prolonged weaning were included before (group 1) and after (group 2) introduction of a quality control measure of a structured and protocolized physiotherapy program. Primary endpoint was the tested dynamometric handgrip strength and the Surgical Intensive Care Unit Optimal Mobilization Score (SOMS). Secondary endpoints were weaning success rate, ventilator-free days, hospital mortality, the prevalence of ICUAW, infections and delirium. Results106 patients were included. Both the SOMS and the handgrip test were significantly improved after introducing the program. Despite no differences in weaning success rates at discharge, the total length of MV was significantly shorter in group 2, which also had lower prevalence of infection and higher probability of survival. ConclusionsProtocolized, systematic physiotherapy resulted in an improvement of the clinical outcome in patients with prolonged weaning. Results were objectifiable with the SOMS and the handgrip test.

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

PurposeTreatment 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 methodsStructured 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. Results18.948 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. ConclusionsThe 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.

Switching from VA-ECMO to a Percutaneous right Ventricular assist device as a Bridge to Recovery in a Case of right Ventricular Myocardial Infarction

Acute right heart failure (RHF) is associated with high morbidity and mortality. Temporary mechanical circulatory support (MCS) is now part of the advanced management strategy for refractory cardiogenic shock (CS). Among such support systems, veno-arterial Extracorporeal Membrane Oxygenation (VA-ECMO) remains the fastest MCS system to set up. The ProtekDuo cannula can be used as a temporary and percutaneous right ventricular assist device (RVAD) in relay with VA-ECMO in the context of prolonged weaning. This case report describes the clinical course of a 69-year-old patient who underwent elective aortic valve replacement surgery complicated by acute RHF due to iatrogenic ligation of the right coronary artery. VA-ECMO was initiated in the context of refractory cardiogenic shock. Faced with prolonged MCS weaning, due to lack of recovery of the right ventricle associated with the absence of any other therapeutic option, a percutaneous RVAD via a ProtekDuo cannula was implanted as a bridge to recovery. The ProtekDuo was gradually weaned while the patient began rehabilitation. The patient was transferred to the medical ward after 5 weeks in the ICU, stayed 5 months in an acute medical setting, went to a rehabilitation center afterward and returned home 6 months after the initial surgery without any neurological sequalae or organ failures. In total, she remained on MCS for 39 days (21 on VA-ECMO and 18 on ProtekDuo). In cases of refractory RHF, after stabilization and organ perfusion restoration under VA-ECMO, it is feasible to switch to a percutaneous RVAD, allowing early mobilization of patients during prolonged MCS weaning until the right ventricle adapts to new loading conditions.

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

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

A physiological model of phrenic nerve excitation by electrical stimulation.

Mechanical ventilation is essential in intensive care treatment but leads to diaphragmatic atrophy, which in turn contributes to prolonged weaning and increased mortality. One approach to prevent diaphragmatic atrophy while achieving pulmonary ventilation is electrical stimulation of the phrenic nerve. To automize phrenic nerve stimulation resulting in lung protective tidal volumes with lowest possible currents, mathematical models are required. Nerve stimulation models are often complex, so many parameters have to be identified prior to implementation. This paper presents a novel, simplified approach to model phrenic nerve excitation to obtain an individualized patient model using a few data points. The latter is based on the idea that nerve fibers are excited when the electric field exceeds a threshold. The effect of the geometry parameter on the model output was analyzed, and the model was validated with measurement data from a pig trial (RMSE in between 0.44 × 10-2and 1.64 × 10-2for parameterized models). The modeled phrenic nerve excitation behaved similarly to the measured tidal volumes, and thus could be used to develop automated phrenic nerve stimulation systems for lung protective ventilation.

Home mechancial ventilation: quality of life and the final stage of life

The evaluation of health-related quality of life (HRQL) has gained importance in recent years. Disease-specific questionnaires are available for respiratory insufficiency, which enable the assessment of HRQL. The Severe Respiratory Insufficiency (SRI) questionnaire, which was specially developed for patients with respiratory insufficiency, is ideal for quantifying the quality of life in patients receiving home mechanical ventilation (HMV). Studies using the SRI questionnaire demonstrated that the physical functioning of patients with chronic lung diseases of various etiologies is significantly impaired, but frequently without significant impairment of psychological well-being. Therefore, severity of the disease and HRQL do not necessarily correlate with each other.Both invasive and non-invasive mechanical ventilation can improve quality of life. Co-morbidity, and above all advanced age, have the highest negative predictive value with regard to in-hospital mortality and weaning failure. The number of patients older than 80 years who remain dependent on invasive HMV after prolonged weaning in Germany is increasing significantly. High dependence on invasive HMV is often associated with a loss of quality of life and autonomy. Thus, ethical issues of the continued treatment of ventilated patients at the end of life are discussed increasingly.After weaning failure, the indication for invasive HMV should be critically examined and should focus on potentially severely reduced quality of life and poor prognosis, as well as the patient's wishes. If previously agreed treatment goals can no longer be achieved during the course of invasive HMV, changing the therapy goals should be discussed within the clinical team, with the patient, their relatives and, if necessary, with legal representatives.In order to avoid overtreatment and unnecessary patient suffering during invasive HMV, advanced care planning should be started as early as possible and if necessary accompanied by palliative medical measures.

Correlation Between Sleep Continuity and Patient-Reported Sleep Quality in Conscious Critically Ill Patients at High Risk of Reintubation: A Pilot Study.

It is well-established that sleep quality of ICU patients is poor, with sleep being highly fragmented by multiple awakenings. These sleep disruptions are associated with poor outcomes such as prolonged weaning duration from mechanical ventilation. Polysomnography can measure sleep continuity, a parameter associated positively with outcomes in patients treated with noninvasive ventilation, but polysomnography is not routinely available in all ICUs, and simple means to assess sleep quality are needed. The Richards-Campbell sleep questionnaire (RCSQ) assesses sleep quality in ICU patients but is difficult to administrate in patients who are not fully awake, and a simpler sleep numeric rating scale (sleep-NRS) has been proposed as an alternative. We here investigated the relationships between sleep continuity and patients-reported sleep quality. Single-center retrospective study. Medical ICU of Poitiers University Hospital. Seventy-two patients were extubated from mechanical ventilation and at high risk of reintubation. None. We analyzed 52 previously recorded polysomnographies in nonsedated and conscious ICU patients. Sleep was recorded the night after extubation. Sleep continuity was measured using an automated scoring algorithm from one electroencephalogram (EEG) channel of the polysomnography. Patient-reported sleep quality was assessed using RCSQ and sleep-NRS. Sleep continuity could be calculated on 45 polysomnographies (age: 68 [58-77], median [25th-75th]) RCSQ (62 [48-72]) and sleep-NRS (6.0 [5.0-7.0]) were obtained in 21 patients and 34 patients, respectively. Our results show a significant correlation between sleep continuity and sleep-NRS (p = 0.0037; ρ = 0.4844; n = 34) but not with RCSQ score (p = 0.6732; ρ = 0.1005; n = 20). Sleep continuity correlates with patient-reported sleep quality assessed using sleep-NRS and may capture the refreshing part of sleep. Sleep-NRS can be easily administered in ICU patients. Sleep continuity and sleep-NRS are simple tools that may prove useful to evaluate sleep quality in ICU patients.