Rapid shallow breathing index

Ultrasonographic evaluation of diaphragm thickness and excursion: correlation with weaning success in trauma patients: prospective cohort study

PURPOSE

Prolonged mechanical ventilation (MV) subjects multiple trauma patients to ventilator-induced diaphragmatic dysfunction. There is limited evidence on the predictive role of diaphragm ultrasound (DUS) for weaning success in multiple trauma patients. Therefore, we evaluated Ultrasound of the diaphragm as a valuable indicator of weaning outcomes, in trauma patients.

MATERIAL AND METHODS

This prospective cohort study included 50 trauma patients from September 2018 to February 2019. DUS was performed twice: upon ICU admission and the first weaning attempt. The diagnostic accuracy of indexes was evaluated by ROC curves.

RESULTS

The study included patients with a mean age of 35.4 ± 17.37, and 78% being male. The median injury severity score was 75 (42-75). The failure group exhibited significantly lower right diaphragmatic excursion (DE) compared to the success group (P = 0.006). In addition, the failure group experienced a significant decrease in both right and left DE from admission to the first attempt of weaning from MV (P < 0.001). Both groups showed a significant decrease in inspiratory and expiratory thickness on both sides during weaning from MV compared to the admission time (P < 0.001). The findings from the ROC analysis indicated that the Rapid shallow breathing index (RSBI) (Sensitivity = 91.67, Specificity = 100), respiratory rate (RR)/DE (Right: Sensitivity = 87.5, Specificity = 92.31), and RR/TF (Thickening Fraction) (Right: Sensitivity = 83.33, Specificity = 80.77) demonstrated high sensitivity and specificity in predicting weaning outcome.

CONCLUSION

In the context of patients with multiple trauma, employing DUC and assessing diaphragmatic excursion, thickness, RR/DE index, RR/TF index, and RSBI can aid in determining successful ventilator weaning.

Structured Light Plethysmography for Non-Invasive Assessment of Respiratory Pattern in Spinal Muscular Atrophy Type 1

BACKGROUND

Spinal muscular atrophy (SMA) type 1 is a severe condition leading to early respiratory failure. Treatment options have become available, yet respiratory outcome measures in SMA type 1 are limited. The aim of this study was to assess the respiratory pattern in SMA type 1 patients via structured light plethysmography (SLP). SLP measures the thoraco-abdominal movements by projecting a light grid onto the anterior thoraco-abdominal surface.

METHODS

Cross-sectional study of consecutive children with SMA type 1. All children underwent motor assessment (CHOP-INTEND) and one-minute tidal breathing recording by SLP in supine position while self-ventilating in room air. The Respiratory rate, the abdominal vs. chest contribution to breath (Relative Expired Abdomen%, Relative Expired Chest%) and the severity of thoraco-abdominal paradox (Phase Angle) were acquired.

RESULTS

Nineteen patients were included, median (IQR) age 2.3 years (1.4-7.9). Their respiratory pattern captured via SLP showed a raised median (IQR) respiratory rate per age of 33.5 bpm (26.6-41.7), a prevalent abdominal contribution to tidal breathing with median (IQR) Relative Expired Abdomen 77% (68-90) vs. Chest 23% (10-32). Thoracoabdominal paradox was detected (median Phase Angle 48.70°) and its severity correlated negatively with CHOP-INTEND (r -0.8, p < 0.01).

CONCLUSIONS

SLP captured and quantified the respiratory features of infants and children with SMA type 1.

The combined use of parasternal intercostal muscle thickening fraction and P0.1 for prediction of weaning outcomes

BACKGROUND

A variety of parameters and diaphragmatic ultrasound in ventilator weaning has been studied extensively, and the findings yield inconsistent conclusions. The parasternal intercostal muscle holds important substantial respiratory reserve capacity when the central drive is enhanced, the predictive value of combining parasternal intercostal muscle ultrasound parameters with P0.1(airway occlusion pressure at 100 msec) in assessing ventilator weaning outcomes is still unknown.

OBJECTIVES

Our study aimed to evaluate the predictive efficacy of parasternal intercostal muscle ultrasound in conjunction with P0.1 in determining weaning failure.

METHODS

We recruited patients who had been admitted to ICU and had been receiving mechanical ventilation for over two days. All patients underwent a half-hour spontaneous breathing trial (SBT) with low-level pressure support ventilation (PSV). They were positioned semi-upright for parasternal intercostal muscle ultrasound evaluations, including parasternal intercostal muscle thickness (PIMT), and parasternal intercostal muscle thickening fraction (PIMTF); P0.1 was obtained from the ventilator. Weaning failure was defined as the need for non-invasive positive pressure ventilation or re-intubation within 48 h post-weaning.

RESULTS

Of the 56 enrolled patients with a mean age of 63.04 ± 15.80 years, 13 (23.2%) experienced weaning failure. There were differences in P0.1 (P = .001) and PIMTF (P = .017) between the two groups, but also in patients with a diaphragm thickness ≥ 2 mm. The predictive threshold values were PIMTF ≥ 13.15% and P0.1 ≥ 3.9 cmH2O for weaning failure. The AUROC for predicting weaning failure was 0.721 for PIMTF, 0.792 for P0.1, and 0.869 for the combination of PIMTF and P0.1.

CONCLUSIONS

The parasternal intercostal muscle thickening fraction and P0.1 are independently linked to weaning failure, especially in patients with normal diaphragm thickness. The combination of parasternal intercostal muscle thickening fraction and P0.1 can serve as a valuable tool for the precise clinical prediction of weaning outcomes.

TRIAL REGISTRATION

Chinese Clinical Trial Registry website (ChiCTR2200065422).

Managing the Chronically Ventilated Critically Ill Population

Advances in intensive care over the past few decades have significantly improved the chances of survival for patients with acute critical illness. However, this progress has also led to a growing population of patients who are dependent on intensive care therapies, including prolonged mechanical ventilation (PMV), after the initial acute period of critical illness. These patients are referred to as the "chronically critically ill" (CCI). CCI is a syndrome characterized by prolonged mechanical ventilation, myoneuropathies, neuroendocrine disorders, nutritional deficiencies, cognitive and psychiatric issues, and increased susceptibility to infections. It is associated with high morbidity and mortality as well as a significant increase in healthcare costs. In this article, we will review disease burden, outcomes, psychiatric effects, nutritional and ventilator weaning strategies as well as the role of palliative care for CCI with a specific focus on those requiring PMV.

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.

Rate of Change of Rapid Shallow Breathing Index and Extubation Outcome in Mechanically Ventilated Patients

Background

Rapid shallow breathing index (RSBI) has been widely used as a predictor of extubation outcome in mechanically ventilated patients. We hypothesize that the rate of change of RSBI between the beginning and end of a 120-minute spontaneous breathing trial (SBT) could be a better predictor of extubation outcome than a single RSBI measured at the end of SBT in mechanically ventilated patients. Methodology. In this prospective observational study, we enrolled 193 patients who met the inclusion criteria, of whom 33 patients were unable to tolerate a 120-minute SBT and were excluded from the study. The study population consisted of 160 patients, categorized into three subgroups: patients with normal lung (no reported history of respiratory diseases), patients with airway disease, and patients with parenchymal disease who completed 120 minutes of SBT on low levels of pressure support ventilation. RSBI was obtained from the ventilator display at the 5th and the 120th minutes of SBT. The rate of change of RSBI (RSBI 5-120) was calculated as (RSBI 2-RSBI 1)/RSBI 1 × 100. Receiver-operating characteristic (ROC) curves were plotted for RSBI 5-120 and RSBI 120 in all patients and among the three subgroups (normal group, airway group, and parenchymal group) to compare the superiority of their best thresholds in predicting extubation failure.

Results

The RSBI 5-120 threshold for extubation failure in the entire patient group was 23% with an overall accuracy of 88% (AUC = 0.933, sensitivity = 91%, and specificity = 86%) and the threshold of RSBI 120 for extubation failure in the entire patient group was 70 breaths/min/L with an overall accuracy of 82% (AUC = 0.899, sensitivity = 85%, and specificity = 81%). In patients in the normal lung group, the threshold of RSBI 5-120 was 22%, with an overall accuracy of 89% (AUC = 0.892, sensitivity = 87.5%, and specificity = 90%), and the RSBI 120 threshold was 70 breaths/min/L, with an overall accuracy of 89% (AUC = 0.956, sensitivity = 88%, and specificity = 90%). The RSBI 5-120 threshold in patients with airway disease was 25% with an accuracy of 86% (AUC = 0.892, sensitivity = 85%, and specificity = 86%) and the threshold of RSBI 120 was 73 breaths/min/L with an accuracy of 83% (AUC = 0.874, sensitivity = 85%, and specificity = 82%). In patients in the parenchymal disease group, the threshold of RSBI 5-120 was 24%, with an accuracy of 90% (AUC = 0.966, sensitivity = 92%, and specificity = 89%) and RSBI 120 threshold was 71 breaths/min/L, which was 88% accurate (AUC = 0.893, sensitivity = 85%, and specificity = 89%).

Conclusion

The rate of change of RSBI between the 5th and 120th minutes was moderately more accurate than the single value of RSBI measured at the 120th minute in predicting extubation outcome.

Comparison of different methods of obtaining the rapid shallow breathing index

OBJECTIVE

To compare the Rapid Shallow Breathing Index (RSBI) obtained by the ventilometer and from mechanical ventilation parameters.

METHODS

Randomized crossover trial, including 33 intubated patients, on mechanical ventilation for at least 24 hours, undergoing spontaneous breathing test. Patients were submitted to the measurement of RSBI by four methods: disconnected from the ventilator through the ventilometer; in Pressure Support Ventilation (PSV) mode at a pressure of 7.ßcm H2O; in Continuous Positive Airway Pressure (CPAP) mode at a pressure of 5.ßcmH2O with flow trigger; in CPAP mode at a pressure of 5.ßcmH2O with pressure trigger.

RESULTS

No significant difference was detected between the RSBI obtained by the ventilometer and in the CPAP mode with flow and pressure triggers, however, in the PSV mode, the values were lower than in the other measurements (p.ß<.ß0.001). By selecting patients from the sample with higher RSBI (... 80 cycles.min-1.L-1), the value of the index obtained by the ventilometer was higher than that obtained in the three options of ventilation methods.

CONCLUSION

The RSBI obtained in the CPAP mode at a pressure of 5.ßcmH2O, in both triggers types, did not differ from that measured by the ventilometer; it is, therefore, an alternative when obtaining it from mechanical ventilation parameters is necessary. However, in the presence of borderline values, the RSBI measured by ventilometer is recommended, as in this method the values are significantly higher than in the three ventilation modalities investigated.

Is diaphragm ultrasound better than rapid shallow breathing index for predicting weaning in critically ill elderly patients?

Introduction

Prolonged weaning is associated with worse clinical outcomes in elderly patients. Beside traditional rapid shallow breathing index (RSBI), diaphragm ultrasound is a promising technique to evaluate the weaning process. We aimed to perform diaphragm ultrasonography for predicting the weaning process and its relation with frailty in the critically ill elderly population.

Materials and Methods

We enrolled thirthy-two patients over 65 years of age who were mechanically ventilated for at least 48 hours. Thickness of diaphragm and excursion were evaluated within 48 h of intubation and during spontaneous breathing trial (SBT). Clinical parameters, frailty, diaphragm ultrasound results were compared according to the weaning status.

Results

Mean age (standard deviation) was 79.3 ± 7.9 years, and 18 (56.3%) patients were classified as weaning failure. Diaphragmatic excursion during SBT was the only statistically significant parameter associated with weaning failure [2.37 cm (0.67) vs 1.43 cm (0.15), p= 0.0359]. There was no statistically significant difference regarding RSBI between the groups [70.5 (46) vs 127.5 (80), p= 0.09]. Baseline thickness of diaphragm and excursion at SBT were moderately correlated with frailty.

Conclusion

Ultrasound can be used to show diaphragm dysfunction in the elderly frail population, and a multifactorial approach to the extubation process may include ultrasound instead of using traditional RSBI alone.

A new index, Respiratory Insufficiency index and Modified Early Warning Scores predict extubation failure

Background

Extubation failure occurs in 5%-20% of patients and is associated with poor clinical outcomes. The primary aim of this project was to determine the predictive ability of the Respiratory Insufficiency (RI) index, Respiratory Oxygenation (ROX) index and Modified Early Warning Score (MEWS) in identifying extubation failure.

Methods

This was a secondary analysis of a prior cross-sectional retrospective study conducted from February 2018 through December 2018 among adult subjects who received mechanical ventilation for more than 24 h. Extubation failure was defined as the need for reintubation or rescue non-invasive ventilation (NIV) within 48 h after planned extubation. Univariate analysis and logistic regression were used to identify the predictors and final model was validated using 10-fold cross validation. Nomogram was constructed based on the final model.

Results

Of 216 enrolled subjects, 46 (21.3%) experienced extubation failure. The median RI index 1-h post extubation was 20 [interquartile range [IQR] 16.33-24.24] for success group and 27.02 [IQR 22.42-33.83] for the failure group (P<0.001). The median ROX index 1-h post extubation was 16.66 [IQR 12.57-19.84] for success group and 11.11 [IQR 8.09-14.67] for failure group (P<0.001). The median MEWS 1-h post extubation was 2 [IQR 1-3] for the success group and 4 [IQR 3-5] for the failure group (P<0.001). In multivariable analysis, age >60 years [OR 3.89 (95% CI 1.56-9.73); P=0.004], MEWS >4 [OR 4.01 (95% CI (1.59-10.14); P=0.003] and, RI index >20 [OR 4.50 (95% CI 1.43-14.21); P=0.010] were independently associated with extubation failure.

Conclusion

In the present study, RI index and MEWS were independently associated with predicting extubation failure within 1 h of extubation. A prospective validation study is warranted to establish the role of these indices in predicting extubation outcome.

Association between microcirculation in spontaneous breathing trial and extubation success

PURPOSE

This study assessed the association between changes in sublingual microcirculation after a spontaneous breathing trial (SBT) and successful extubation.

MATERIALS AND METHODS

Sublingual microcirculation was assessed using an incident dark-field video microscope before and after each SBT and before extubation. Microcirculatory parameters before the SBT, at the end of the SBT, and before extubation were compared between the successful and failed extubation groups.

RESULTS

Forty-seven patients were enrolled and analysed in this study (34 patients in the successful extubation group and 13 patients in the failed extubation group). At the end of the SBT, the weaning parameters did not differ between the two groups. However, the total small vessel density (21.2 [20.4-23.7] versus 24.9 [22.6-26.5] mm/mm²), perfused small vessel density (20.6 [18.5-21.8] versus 23.1 [20.9-25] mm/mm²), proportion of perfused small vessels (91 [87-96] versus 95 [93-98] %), and microvascular flow index (2.8 [2.7-2.9] versus 2.9 [2.9-3]) were significantly lower in the failed extubation group than in the successful extubation group. The weaning and microcirculatory parameters did not differ significantly between the two groups before the SBT.

CONCLUSIONS

More patients are required to investigate the difference between baseline microcirculation before a successful SBT and the change in microcirculation at the end of the SBT between the successful and failed extubation groups. Better sublingual microcirculatory parameters at the end of SBT and before extubation are associated with successful extubation.

The ratio of respiratory rate to diaphragm thickening fraction for predicting extubation success

BACKGROUND

Several parameters are used to predict successful extubation but their accuracy varies among studies. We hypothesized that combining conventional and diaphragmatic parameters would be more effective than using just one. Our primary objective was to evaluate the performance of the respiratory rate in relation to the diaphragm thickening fraction (RR/DTF) ratio to predict the success of extubation.

METHODS

We enrolled 130 adult patients who required invasive mechanical ventilation, planned to be extubated, and used a spontaneous breathing trial (SBT) in the intensive care unit from July 2020 to April 2022. We measured the conventional parameters and the diaphragmatic parameters 2 h after SBT. The RR/DTF was calculated by dividing the respiratory rate (RR) by the diaphragm thickening fraction (DTF). The definition of weaning success is successful extubation within 48 h.

RESULTS

Of 130 patients, 8 patients (6.2%) were reintubated within 48 h. The RR/DTF was significantly lower in the successful extubation group than in the extubation failure group (right hemidiaphragm; 0.47 (0.33-0.64) vs 1.1 (0.6-2.32), p < 0.001 and left hemidiaphragm; 0.45 (0.31-0.65) vs 0.78 (0.48-1.75), p < 0.001). The right RR/DTF using a cut-off point at ≤ 0.81 had a sensitivity of 87.7%, a specificity of 75%, and areas under the receiver operating characteristic curve (AUROC) of 0.762 for predicting successful extubation (p = 0.013). The sensitivity, specificity, and AUROC for predicting extubation success of right DTF at a cut-off point of ≥ 26.2% were 84.3%, 62.5%, and 0.775, respectively (p = 0.009).

CONCLUSION

The RR/DTF ratio is a promising tool for predicting extubation outcome. Additionally, using RR/DTF was more reliable than conventional or diaphragmatic parameters alone in predicting extubation success.

Emerging Applications of Extracardiac Ultrasound in Critically Ill Cardiac Patients

Point-of-care ultrasound has evolved as an invaluable diagnostic modality and procedural guidance tool in the care of critically ill cardiac patients. Beyond focused cardiac ultrasound, additional extracardiac ultrasound modalities may provide important information at the bedside. In addition to new uses of existing modalities, such as pulsed-wave Doppler ultrasound, the development of new applications is fostered by the implementation of additional features in mid-range ultrasound machines commonly acquired for intensive care units, such as tissue elastography, speckle tracking, and contrast-enhanced ultrasound quantification software. This review explores several areas in which ultrasound imaging technology may transform care in the future. First, we review how lung ultrasound in mechanically ventilated patients can enable the personalization of ventilator parameters and help to liberate them from mechanical ventilation. Second, we review the role of venous Doppler in the assessment of organ congestion and how tissue elastography may complement this application. Finally, we explore how contrast-enhanced ultrasound could be used to assess changes in organ perfusion.

Tests and Indices Predicting Extubation Failure in Children: A Systematic Review and Meta-analysis

INTRODUCTION

There is lack of consensus on what constitutes best practice when assessing extubation readiness in children. This systematic review aims to synthesize data from existing literature on pre-extubation assessments and evaluate their diagnostic accuracies in predicting extubation failure (EF) in children.

METHODS

A systematic search in PubMed, EMBASE, Web of Science, CINAHL, and Cochrane was performed from inception of each database to 15 July 2021. Randomized controlled trials or observational studies that studied the association between pre-extubation assessments and extubation outcome in the pediatric intensive care unit population were included. Meta-analysis was performed for studies that report diagnostic tests results of a combination of parameters.

RESULTS

In total, 41 of 11,663 publications screened were included (total patients, n = 8111). Definition of EF across studies was heterogeneous. Fifty-five unique pre-extubation assessments were identified. Parameters most studied were: respiratory rate (RR) (13/41, n = 1945), partial pressure of arterial carbon dioxide (10/41, n = 1379), tidal volume (13/41, n = 1945), rapid shallow breathing index (RBSI) (9/41, n = 1400), and spontaneous breathing trials (SBT) (13/41, n = 5652). Meta-analysis shows that RSBI, compliance rate oxygenation pressure (CROP) index, and SBT had sensitivities ranging from 0.14 to 0.57. CROP index had the highest sensitivity [0.57, 95% confidence interval (CI) 0.4-0.73] and area under curve (AUC, 0.98). SBT had the highest specificity (0.93, 95% CI 0.92-0.94).

CONCLUSIONS

Pre-extubation assessments studied thus far remain poor predictors of EF. CROP index, having the highest AUC, should be further explored as a predictor of EF. Standardizing the EF definition will allow better comparison of pre-extubation assessments.

Comprehensive breathing variability indices enhance the prediction of extubation failure in patients on mechanical ventilation

BACKGROUND AND OBJECTIVE

Despite the numerous studies on extubation readiness assessment for patients who are invasively ventilated in the intensive care unit, a 10-15% extubation failure rate persists. Although breathing variability has been proposed as a potential predictor of extubation failure, it is mainly assessed using simple statistical metrics applied to basic respiratory parameters. Therefore, the complex pattern of breathing variability conveyed by continuous ventilation waveforms may be underexplored.

METHODS

Here, we aimed to develop novel breathing variability indices to predict extubation failure among invasively ventilated patients. First, breath-to-breath basic and comprehensive respiratory parameters were computed from continuous ventilation waveforms 1 h before extubation. Subsequently, the basic and advanced variability methods were applied to the respiratory parameter sequences to derive comprehensive breathing variability indices, and their role in predicting extubation failure was assessed. Finally, after reducing the feature dimensionality using the forward search method, the combined effect of the indices was evaluated by inputting them into the machine learning models, including logistic regression, random forest, support vector machine, and eXtreme Gradient Boosting (XGBoost).

RESULTS

The coefficient of variation of the dynamic mechanical power per breath (CV-MPd[J/breath]) exhibited the highest area under the receiver operating characteristic curve (AUC) of 0.777 among the individual indices. Furthermore, the XGBoost model obtained the best AUC (0.902) by combining multiple selected variability indices.

CONCLUSIONS

These results suggest that the proposed novel breathing variability indices can improve extubation failure prediction in invasively ventilated patients.

A 30-Minute Spontaneous Breathing Trial Misses Many Children Who Go On to Fail a 120-Minute Spontaneous Breathing Trial

BACKGROUND

The optimal length of spontaneous breathing trials (SBTs) in children is unknown.

RESEARCH QUESTIONS

What are the most common reasons for SBT failure in children, and when do they occur? Can clinical parameters at the 30-min mark of a 120-min SBT predict outcome?

STUDY DESIGN AND METHODS

We performed a secondary analysis of a clinical trial in pediatric ARDS, in which 2-h SBTs are conducted daily. SBT failure is based on objective criteria, including esophageal manometry for effort of breathing, categorized as passage, early failure (≤ 30 min), or late failure (30-120 min). Spirometry was used to calculate respiratory rate (RR), tidal volume (Vt), and rapid shallow breathing index (RSBI), in addition to pulse oximetry and capnography. Predictive models evaluated parameters at 30 min against SBT outcome, using receiver operating characteristic plots and area under the curve.

RESULTS

We included 100 children and 305 SBTs, with 42% of SBTs being successful, 32% failing within 30 min, and 25% failing between 30 and 120 min. Of the patients passing SBTs at 30 min, 40% went on to fail by 120 min. High respiratory effort (esophageal manometry) was present in > 80% of failed SBTs. At the 30-min mark, there were no clear thresholds for RR, Vt, RSBI, Fio2, oxygen saturation, or capnography that could reliably predict SBT outcome. Multivariable modeling identified RR (P < .001) and RSBI > 7 (P = .034) at 30 min, pre-SBT inspiratory pressure level (P = .009), and pre-SBT retractions (P = .042) as predictors for SBT failure, but this model performed poorly in an independent validation set with the receiver operating characteristic plot crossing the reference line (area under the curve, 0.67).

INTERPRETATION

A 30-min SBT may be too short in children recovering from pediatric ARDS because many go on to fail between 30 and 120 min. Reassuring values of Vt, RR, and gas exchange at 30 min do not reliably predict SBT passage at 2 h, likely because they do not capture the effort of breathing.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT03266016; URL: www.

CLINICALTRIALS

gov.

Incidence of extubation failure and its predictors among adult patients in intensive care unit of low-resource setting: A prospective observational study

BACKGROUND

Previous studies have found an association between various predictors and extubation failure (EF) in intensive care units (ICUs). However, this problem remains unexplored in low-resource settings, where predicting the extubation outcomes are more challenging. This study investigates the incidence of EF and its predictors among patients who received mechanical ventilation (MV).

METHODS

This is a prospective observational study of 123 patients' ≥ 18 years of age receiving MV for ≥ 48 hours and tolerated spontaneous breathing trials (SBTs) in the ICU of a low-resource setting. We collected data on the baseline characteristics and clinical profiles before and after SBTs. Patients were categorized into extubation failure (EF) and extubation success (ES) groups. Multivariate logistic regression analyses were performed to identify independent predictors for EF. A p-value < 0.05 is considered statistically significant.

RESULTS

We included 123 patients, and 42 (34.15%) had developed EF. The identified predictors for EF: Moderate to copious secretions (adjusted odds ratio [AOR]: 3.483 [95% confidence interval [CI] 1.10-11.4]), age > 60 years of age ([AOR]: 4.157 [95% CI 1.38-12.48]), and prolonged duration of MV ≥ 10 days ([AOR]: 4.77 [95% CI 1.55-14.66]).

CONCLUSION

Moderate to copious secretions, patients > 60 years of age, and prolonged duration of MV ≥ 10 days were the best predictors of EF. Based on our findings, we recommend that the identified predictors could help in the decision-making process of extubation from MV.

Identification and Prevention of Extubation Failure by Using an Automated Continuous Monitoring Alert Versus Standard Care

BACKGROUND

Postextubation monitoring helps identify patients at risk of developing respiratory failure. This study aimed to evaluate the effect of our standard respiratory therapist (RT) assessment tool versus an automated continuous monitoring alert to initiate postextubation RT-driven care on the re-intubation rate.

METHODS

This was a single-center randomized clinical trial from March 2020 to September 2021 of adult subjects who received mechanical ventilation for > 24 h and underwent planned extubation in the ICU. The subjects were assigned to the standard RT assessment tool or an automated monitoring alert to identify the need for postextubation RT-driven care. The primary outcome was the need for re-intubation due to respiratory failure within 72 h. Secondary outcomes included re-intubation within 7 d, ICU and hospital lengths of stay, hospital mortality, ICU cost, and RT time associated with patient assessment and therapy provision.

RESULTS

Of 234 randomized subjects, 32 were excluded from the primary analysis due to disruption in RT-driven care during the surge of patients with COVID-19, and 1 subject was excluded due to delay in the automated monitoring initiation. Analysis of the primary outcome included 85 subjects assigned to the standard RT assessment group and 116 assigned to the automated monitoring alert group to initiate RT-driven care. There was no significant difference between the study groups in re-intubation rate, median length of stay, mortality, or ICU costs. The RT time associated with patient assessment (P < .001) and therapy provided (P = .031) were significantly lower in the automated continuous monitoring alert group.

CONCLUSIONS

In subjects who received mechanical ventilation for > 24 h, there were no significant outcome or cost differences between our standard RT assessment tool or an automated monitoring alert to initiate postextubation RT-driven care. Using an automated continuous monitoring alert to initiate RT-driven care saved RT time. (ClinicalTrials.gov registration NCT04231890).

Diaphragmatic ultrasonography-based rapid shallow breathing index for predicting weaning outcome during a pressure support ventilation spontaneous breathing trial

Background

The optimum timing to wean is crucial to avoid negative outcomes for mechanically ventilated patients. The rapid shallow breathing index (RSBI), a widely used weaning index, has limitations in predicting weaning outcomes. By replacing the tidal volume of the RSBI with diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) assessed by ultrasonography, we calculated two weaning indices, the diaphragmatic excursion rapid shallow breathing index (DE-RSBI, respiratory rate [RR]/DE) and the diaphragm thickening fraction rapid shallow breathing index (DTF-RSBI, RR/DTF). The aim of this study was to evaluate the predictive values of DTF-RSBI, DE-RSBI and traditional RSBI in weaning failure.

Methods

This prospective observational study included patients undergoing mechanical ventilation (MV) for > 48 h and who were readied for weaning. During a pressure support ventilation (PSV) spontaneous breathing trial (SBT), right hemidiaphragmatic excursion and DTF were measured by bedside ultrasonography as well as RSBI. Weaning failure was defined as: (1) failing the SBT and (2) SBT success but inability to maintain spontaneous breathing for more than 48 h without noninvasive or invasive ventilation. A receiver operator characteristic (ROC) curve was used for analyzing the diagnostic accuracy of RSBI, DE-RSBI, and DTF-RSBI.

Results

Of the 110 patients studied, 37 patients (33.6%) failed weaning. The area under the ROC (AUROC) curves for RSBI, DE-RSBI, and DTF-RSBI for predicting failed weaning were 0.639, 0.813, and 0.859, respectively. The AUROC curves for DE-RSBI and DTF-RSBI were significantly higher than for RSBI (P = 0.004 and P < 0.001, respectively). The best cut-off values for predicting failed weaning were RSBI > 51.2 breaths/min/L, DE-RSBI > 1.38 breaths/min/mm, and DTF-RSBI > 78.1 breaths/min/%.

Conclusions

In this study, two weaning indices determined by bedside ultrasonography, the DE-RSBI (RR/DE) and DTF-RSBI (RR/DTF), were shown to be more accurate than the traditional RSBI (RR/VT) in predicting weaning outcome during a PSV SBT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02133-5.

Utility of the One-time HACOR Score as a Predictor of Weaning Failure from Mechanical Ventilation: A Prospective Observational Study

Aim

To determine the utility of the HACOR score in predicting weaning failure in resource-limited settings.

Objectives

The primary objective was to determine a cut-off value of the HACOR score, sensitivity, and specificity to predict failed weaning. The secondary objective was to determine which out of five components of the score was significantly different between the successful weaning and the failed weaning groups.

Introduction

Most weaning indices are either inaccurate or are dependent on complex ventilatory parameters, which are difficult to measure in resource-limited settings. This study aimed to determine the utility of the HACOR score consisting of heart rate, acidosis, consciousness level, oxygenation, and respiratory rate as a predictor of weaning in the intensive care unit.

Materials and methods

It was a prospective observational study on 120 patients between 18 and 90 years. The HACOR score was evaluated at 30 minutes of spontaneous breathing trial (SBT). The total duration of SBT was 120 minutes.

Results

Out of 120 patients, 83 (69.2%) had successful weaning, whereas 37 (30.8%) had weaning failure. The median and interquartile range (IQR) of the HACOR score in the successful weaning group was 2 (0–3) and 6 (5–8) in the failed weaning group (p-value <0.001). There was a significant difference in each of the five components of the HACOR score between the successful and failed weaning groups (p <0.05). HACOR score ≥5 predicted failed weaning, sensitivity 83.8%, specificity 96.4%, area under the curve (AUC) 0.950, and 95% confidence interval (CI) [0.907–0.993], p <0.001. Multivariable logistic regression analysis showed that HACOR score ≥5 is an independent predictor of weaning failure [p <0.001, 95% CI (1.9–4.2), adjusted odds ratio 2.82].

Conclusion

A HACOR score ≥5 is an excellent predictor of weaning failure. This score may be useful as a weaning strategy in the intensive care unit.

How to cite this article

Chaudhuri S, Gupta N, Adhikari SD, Todur P, Maddani SS, Rao S. Utility of the One-time HACOR Score as a Predictor of Weaning Failure from Mechanical Ventilation: A Prospective Observational Study. Indian J Crit Care Med 2022;26(8):900–905.

Ethical approval

Prior to the commencement of the study, Institutional Ethics Committee permission was obtained (IEC: 197/2021) and Clinical Trial Registry of India (CTRI) registration was done before recruitment (CTRI/2021/07/035139). We obtained written informed consent from the legally authorized representative prior to recruiting patients for the study.

Identifying Novel Clusters of Patients With Prolonged Mechanical Ventilation Using Trajectories of Rapid Shallow Breathing Index

Objective

Patients with prolonged mechanical ventilation (PMV) are comprised of a heterogeneous population, creating great challenges for clinical management and study design. The study aimed to identify subclusters of PMV patients based on trajectories of rapid shallow breathing index (RSBI), and to develop a machine learning model to predict the cluster membership based on baseline variables.

Methods

This was a retrospective cohort study conducted in respiratory care center (RCC) at a tertiary academic medical center. The RCC referral criteria were patients with mechanical ventilation for at least 21 days with stable hemodynamic and oxygenation status. Patients admitted to the RCC from April 2009 to December 2020 were screened. Two-step clustering through linear regression modeling and k-means was employed to find clusters of the trajectories of RSBI. The number of clusters was chosen by statistical metrics and domain expertise. A gradient boosting machine (GBM) was trained, exploiting variables on RCC admission, to predict cluster membership.

Results

A total of 1371 subjects were included in the study. Four clusters were identified: cluster A showed persistently high RSBI; cluster B was characterized by a constant low RSBI over time; Cluster C was characterized by increasing RSBI; and cluster D showed a declining RSBI. Cluster A showed the highest mortality rate (72%), followed by cluster D (63%), C (62%) and B (61%; p = 0.005 for comparison between 4 clusters). GBM was able to predict cluster membership with an accuracy of &gt; 0.95 in ten-fold cross validation. Highly ranked variables for the prediction of clusters included thyroid-stimulating hormone (TSH), cortisol, platelet, free thyroxine (T4) and serum magnesium.

Conclusions

Patients with PMV are composed of a heterogeneous population that can be classified into four clusters by using trajectories of RSBI. These clusters can be easily predicted with baseline clinical variables.

Point of care diaphragm ultrasound in mechanically ventilated children: A predictive tool to detect extubation failure

BACKGROUND

Children should be weaned from the ventilator once their clinical condition improves. Extubation failure is associated with poorer clinical outcomes in children. Predictive indicators of successful extubation are needed. This study aims to evaluate the predictive value of ultrasonographic diaphragm imaging could help predict weaning success.

METHODS

In this prospective, observational study conducted between March and December 2021, children between 1 month and 10 years of age who were mechanically ventilated for more than 48 h were included. Diaphragm ultrasound (DUS) examinations were performed at the end of 2-h extubation readiness test (ERT). The end-inspiratory thickness (DTi), end-expiratory thickness (DTe), diaphragmatic thickening fraction (DTF), diaphragmatic excursion (DE), inspiratory slope (IS), and expiratory slope (ES) were evaluated.

RESULTS

Twenty-four (60%) patients were successfully extubated, while 16 (40%) required invasive or noninvasive mechanical ventilation support which were classified as failed extubation group. Three of the sixteen patients in the failed extubation group required reintubation. DTF was significantly greater in the successful weaning group (55.05 ± 23.75% vs. 30.9 ± 10.38%) (p < 0.001). DE was significantly greater in the successful weaning group (14 ± 4.4 mm vs. 11.05 ± 3.25 mm) (p < 0.001). DTF and DE were found to have a sensitivity and specificity of 91.67%, 87.50%, 83.33%, and 81.25%, respectively.

CONCLUSION

Diaphragm ultrasound is a feasible and promising tool to guide physicians during weaning from invasive mechanical ventilation. Among all DUS measurements, the DE and DTF indexes showed better performance in extubation failure than other diaphragmatic parameters.

Rapid Shallow Breathing Index as a Predictor for Intubation and Mortality in Acute Respiratory Failure

BACKGROUND

Noninvasive ventilation (NIV) is one of the most important therapeutic tools in patients with acute respiratory failure. However, in case of incorrect patient selection it can delay necessary intubation and is associated with complications and even mortality. Patient selection, therefore, plays a key role in therapeutic success. The purpose of this study was to determine the value of the rapid shallow breathing index (RSBI) in predicting the failure of NIV.

METHODS

This prospective observational study was conducted in the emergency department (ED) of a tertiary hospital. Adults presenting to the ED with acute respiratory failure were included in the study. The success of RSBI values measured initially (RSBI 1) and at 30 min (RSBI 2) and the difference between these 2 values (Δ RSBI) in predicting subjects' intubation requirement and survival was tested using multivariate logistic regression analysis.

RESULTS

Two hundred sixty-seven subjects were included in the study. RSBI 1, RSBI 2, and Δ RSBI values differed significantly between the intubated and non-intubated subjects. According to the multivariate model, RSBI 1 and RSBI 2 > 105, Δ RSBI < 19, heart rate > 100 beats/min, and S_pO2 < 92% were significantly associated with intubation requirement. RSBI 1, RSBI 2, and Δ RSBI values also differed significantly between subjects with a fatal course and surviving individuals. According to the multivariate model, RSBI 2 > 105, Δ RSBI < 19, heart rate > 100, and increasing age were associated with in-hospital mortality.

CONCLUSIONS

RSBI can be a successful marker in predicting the failure of NIV and predicting in-hospital mortality in patients admitted to the ED with acute respiratory failure.

Prediction Model of Extubation Outcomes in Critically Ill Patients: A Multicenter Prospective Cohort Study

Liberation from mechanical ventilation is of great importance owing to related complications from extended ventilation time. In this prospective multicenter study, we aimed to construct a versatile model for predicting extubation outcomes in critical care settings using obtainable physiological predictors. The study included patients who had been extubated after a successful 30 min spontaneous breathing trial (SBT). A multivariable logistic regression model was constructed to predict extubation outcomes (successful extubation without reintubation and uneventful extubation without reintubation or noninvasive respiratory support) using eight parameters: age, heart failure, respiratory disease, rapid shallow breathing index (RSBI), PaO2/FIO2, Glasgow Coma Scale score, fluid balance, and endotracheal suctioning episodes. Of 499 patients, 453 (90.8%) and 328 (65.7%) achieved successful and uneventful extubation, respectively. The areas under the curve for successful and uneventful extubation in the novel prediction model were 0.69 (95% confidence interval (CI), 0.62−0.77) and 0.70 (95% CI, 0.65−0.74), respectively, which were significantly higher than those in the conventional model solely using RSBI (0.58 (95% CI, 0.50−0.66) and 0.54 (95% CI, 0.49−0.60), p = 0.004 and <0.001, respectively). The model was validated using a bootstrap method, and an online application was developed for automatic calculation. Our model, which is based on a combination of generally obtainable parameters, established an accessible method for predicting extubation outcomes after a successful SBT.

Influencing factors for tracheostomy in patients with acute traumatic C3-C5 spinal cord injury and acute respiratory failure

BACKGROUND

Patients with traumatic spinal cord injury (SCI) at C3-C5 have a wide range of tracheostomy rates (27%-75%), and the influencing factors for tracheostomy remain unclear. We conducted a retrospective case-control study to identify the influencing factors for tracheostomy in this subset of patient population.

METHODS

A total of 101 acute traumatic C3-C5 SCI patients with acute respiratory failure requiring translaryngeal intubation and invasive mechanical ventilation (IMV) for more than 48 hours were identified and divided into the no tracheostomy (No-TCO, n = 59) and tracheostomy group (TCO, n = 42) groups. Clinical data were retrospectively reviewed and analyzed.

RESULTS

Compared with the No-TCO patients, the TCO patients had a higher proportion of C3 level injury, lower Glasgow Coma Scale (GCS), and lower blood hemoglobin levels at admission. During the first weaning attempt, the TCO patients had lower levels of maximal inspiratory pressure, maximal expiratory pressure, and minute ventilation but had a higher level of rapid shallow breathing index (RSBI). The TCO patients had longer durations of IMV, ICU stay, and hospitalization compared with the No-TCO patients. Moreover, due to prolonged IMV, the TCO patients had a higher incidence of complications, including ventilator-associated pneumonia, bacteremia, urinary tract infection, and acute kidney injury compared with the No-TCO patients. Multivariate logistic regression analysis revealed that low GCS at admission and high initial RSBI were independent risk factors for tracheostomy. Importantly, a combination of these two influencing factors synergistically increased the odds ratio for tracheostomy.

CONCLUSION

Low GCS at admission and high initial RSBI are two independent influencing factors that synergistically impact tracheostomy in our patients. These findings are helpful for making the decision of performing tracheostomy in this subset of patient population.

Diaphragm ultrasound as a better predictor of successful extubation from mechanical ventilation than rapid shallow breathing index

Background

In 3%–19% of patients, reintubation is needed 48–72 hours following extubation, which increases intensive care unit (ICU) morbidity, mortality, and expenses. Extubation failure is frequently caused by diaphragm dysfunction. Ultrasonography can be used to determine the mobility and thickness of the diaphragm. This study looked at the role of diaphragm excursion (DE) and thickening fraction in predicting successful extubation from mechanical ventilation.

Methods

Thirty-one patients were extubated with the advice of an ICU consultant using the ICU weaning regimen and diaphragm ultrasonography was performed. Ultrasound DE and thickening fraction were measured three times: at the commencement of the T-piece experiment, at 10 minutes, and immediately before extubation. All patients' parameters were monitored for 48 hours after extubation. Rapid shallow breathing index (RSBI) was also measured at the same time.

Results

Successful extubation was significantly correlated with DE (P<0.001). Receiver curve analysis for DE to predict successful extubation revealed good properties (area under the curve [AUC], 0.83; P<0.001); sensitivity, 77.8%; specificity, 84.6%; positive predictive value (PPV), 84.6 %; negative predictive value (NPV), 73.3% while cut-off value, 11.43 mm. Diaphragm thickening fraction (DTF) also revealed moderate curve properties (AUC, 0.69; P=0.06); sensitivity, 61.1%; specificity, 84.6%; PPV, 87.5%; NPV, 61.1% with cut-off value 22.33% although former one was slightly better. RSBI could not reach good receiver operating characteristic value at cut-off points 100 breaths/min/L (AUC, 0.58; P=0.47); sensitivity, 66.7%; specificity, 53.8%; PPV, 66.7%; NPV, 53.8%).

Conclusions

To decrease the rate of reintubation, DE and DTF are better indicators of successful extubation. DE outperforms DTF.

Impact of Inspiratory Muscle Training on Weaning Parameters in Prolonged Ventilator-Dependent Patients: A Preliminary Study

Introduction

Patients require prolonged mechanical ventilation to overcome respiratory failure in the chronic respiratory care ward; however, how to facilitate ventilator weaning using a nurse-led strategy is limited.

Objectives

This study aimed to examine the impact of adjusting ventilator trigger sensitivity as inspiratory muscle training on weaning parameters in patients with prolonged ventilator dependence.

Methods

Multiple pre-test–post-test with a non-equivalent control group design was conducted at a chronic respiratory care ward in southern Taiwan. A convenience sampling method was used to recruit patients who received prolonged mechanical ventilation for more than 21 days into control (n  =  20) and intervention groups (n  =  22). Adjustment of ventilator trigger sensitivity started from 10% of the initial maximum inspiratory pressure and increased to 40% after a training period of six weeks. The weaning parameters were collected for pre-test and multiple post-tests, and statistical analysis of treatment effects was performed using the generalized estimating equation.

Results

Magnitude of weaning parameters was significantly higher in the intervention group after the six-week training, including maximum inspiratory pressure, rapid shallow breathing index, tidal volume, and ratio of arterial-to-inspired oxygen.

Conclusion

Adjustment of ventilator trigger sensitivity as inspiratory muscle training can help prolonged ventilator-dependent patients improve their respiratory muscle strength, breathing patterns, and oxygenation.

The Usefulness of the Rapid Shallow Breathing Index in Predicting Successful Extubation: A Systematic Review and Meta-analysis

BACKGROUND

Clinicians use several measures to ascertain whether individual patients will tolerate liberation from mechanical ventilation, including the rapid shallow breathing index (RSBI).

RESEARCH QUESTION

Given varied use of different thresholds, patient populations, and measurement characteristics, how well does RSBI predict successful extubation?

STUDY DESIGN AND METHODS

We searched six databases from inception through September 2019 and selected studies reporting the accuracy of RSBI in the prediction of successful extubation. We extracted study data and assessed quality independently and in duplicate.

RESULTS

We included 48 studies involving RSBI measurements of 10,946 patients. Pooled sensitivity for RSBI of < 105 in predicting extubation success was moderate (0.83 [95% CI, 0.78-0.87], moderate certainty), whereas specificity was poor (0.58 [95% CI, 0.49-0.66], moderate certainty) with diagnostic ORs (DORs) of 5.91 (95% CI, 4.09-8.52). RSBI thresholds of < 80 or 80 to 105 yielded similar sensitivity, specificity, and DOR. These findings were consistent across multiple subgroup analyses reflecting different patient characteristics and operational differences in RSBI measurement.

INTERPRETATION

As a stand-alone test, the RSBI has moderate sensitivity and poor specificity for predicting extubation success. Future research should evaluate its role as a permissive criterion to undergo a spontaneous breathing trial (SBT) for patients who are at intermediate pretest probability of passing an SBT.

TRIAL REGISTRY

PROSPERO; No.: CRD42020149196; URL: www.crd.york.ac.uk/prospero/.

Flow Index accurately identifies breaths with low or high inspiratory effort during pressure support ventilation

Background

Flow Index, a numerical expression of the shape of the inspiratory flow-time waveform recorded during pressure support ventilation, is associated with patient inspiratory effort. The aim of this study was to assess the accuracy of Flow Index in detecting high or low inspiratory effort during pressure support ventilation and to establish cutoff values for the Flow index to identify these conditions. The secondary aim was to compare the performance of Flow index,of breathing pattern parameters and of airway occlusion pressure (P_0.1) in detecting high or low inspiratory effort during pressure support ventilation.

Methods

Data from 24 subjects was included in the analysis, accounting for a total of 702 breaths. Breaths with high inspiratory effort were defined by a pressure developed by inspiratory muscles (P_musc) greater than 10 cmH₂O while breaths with low inspiratory effort were defined by a P_musc lower than 5 cmH₂O. The areas under the receiver operating characteristic curves of Flow Index and respiratory rate, tidal volume,respiratory rate over tidal volume and P_0.1 were analyzed and compared to identify breaths with low or high inspiratory effort.

Results

P_musc, P_0.1, Pressure Time Product and Flow Index differed between breaths with high, low and intermediate inspiratory effort, while RR, RR/V_T and V_T/kg of IBW did not differ in a statistically significant way. A Flow index higher than 4.5 identified breaths with high inspiratory effort [AUC 0.89 (CI 95% 0.85–0.93)], a Flow Index lower than 2.6 identified breaths with low inspiratory effort [AUC 0.80 (CI 95% 0.76–0.83)].

Conclusions

Flow Index is accurate in detecting high and low spontaneous inspiratory effort during pressure support ventilation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03855-4.

Correlation between Handgrip Strength and Rapid Shallow Breathing Index for Assessment of Weaning from Mechanical Ventilation

Background

Assessment of weaning from mechanical ventilation (MV) is an important process. Rapid shallow breathing index (RSBI) is a standard tool to evaluate a patient's readiness before the spontaneous breathing trial (SBT). Handgrip strength (HGS) is an alternative method for assessment of respiratory muscle strength. Relationship between HGS and RSBI has not been explored. This study aimed to determine the correlation between HGS and RSBI to predict successful extubation in mechanically ventilated patients.

Methods

A prospective study was conducted in screened 120 patients requiring MV with tracheal intubation >48 h. HGS was performed at 48 h after intubation, 10 min before and 30 min after SBT, and 1 h after extubation. RSBI was performed at 10 min before SBT.

Results

A total of 93 patients (58% men) were included in the final analysis. Mean age was 71.6 ± 15.2 years. Patients admitted in general medical wards were 84.9%. APACHE II score was 13.5 ± 4.7. Most patients were intubated from pneumonia (39.8%). Weaning failure was 6.5%. The main result shows that HGS was negatively correlated with RSBI (regression coefficient −0.571, P < 0.001). The equation for predicting RSBI, derived from the linear regression model, was predicted RSBI (breaths/min/L) = 39.285 + (age ∗ 0.138)–(HGS ∗ 0.571).

Conclusions

HGS had significantly negative correlation with RSBI for assessment of weaning from MV. A prospective study of the HGS cutoff value is needed to investigate the difference between patients who succeeded and those who failed extubation. This trial is registered with TCTR20180323004.

Resting Breathing Instability During Wakefulness as a Predictor of Clinical Outcome in COPD

BACKGROUND

Dyspnea is a common symptom in patients with COPD. It causes physical inactivity and impaired health-related quality of life. Although optimal breathing methods alleviate dyspnea, it is unclear whether breathing instability has a clinical impact on patients with COPD. This study aimed to investigate whether resting breathing instability during wakefulness was associated with dyspnea assessed by the modified Medical Research Council (mMRC) dsypnea scale and whether breathing instability can be a novel predictor of clinical outcomes.

METHODS

Forty-four subjects with stable COPD were enrolled (mean age, 71.0 y). Resting breathing was monitored for 15 min by using respiratory inductance plethysmography. Breathing instability was evaluated with the coefficient of variation for breath-by-breath respiratory duration and tidal volume ([Formula: see text]) by using an artifact-free respiratory signal for 5 min. Pulmonary function testing and blood gas analysis were performed (mean FEV₁ percent of predicted, 68.5%). Questionnaires with regard to dyspnea and health-related quality of life were also completed. Exacerbations were recorded prospectively for 1 year after the initial assessment.

RESULTS

The coefficients of variation for [Formula: see text] were significantly higher in the subjects with an mMRC dyspnea scale score ≥ 2 versus those with an mMRC dyspnea scale score < 2 (26.4 ± 7.4% vs 20.3 ± 6.4%, P = .006) . The coefficients of variation for respiratory duration and V_T were not associated with age, body mass index, and pulmonary function variables. In multivariate analysis, FEV₁ percent of predicted and coefficient of variation for [Formula: see text] remained significant predictors for an mMRC dyspnea scale score ≥ 2 (P = .004 and P = .01, respectively). Coefficient of variation values were also correlated with several health-related quality of life domains. The exacerbation frequency was associated with the coefficient of variation for [Formula: see text].

CONCLUSIONS

Resting breathing pattern during wakefulness is a novel assessment tool for severity of dyspnea, which can be one of the predictors for exacerbation in patients with COPD.

Predictors of Successful Weaning from Noninvasive Ventilation in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Single-Center Retrospective Cohort Study

Purpose

Noninvasive ventilation (NIV) is often required for patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), and it can significantly reduce the need for endotracheal intubation. Currently, there is no standard method for predicting successful weaning from NIV. Therefore, we aimed to evaluate whether a weaning index can predict NIV outcomes of patients with AECOPD.

Methods

This study was conducted at a single academic public hospital in northern Taiwan from February 2019 to January 2021. Patients with AECOPD admitted to the hospital with respiratory failure who were treated with NIV were included in the study. Univariate and multivariate logistic regression analyses were used to identify independent predictors of successful weaning from NIV. Receiver operating characteristic curve methodology was used to assess the predictive capacity.

Results

A total of 85 patients were enrolled, 65.9% of whom were successfully weaned from NIV. The patients had a mean age of 75.8 years and were mostly men (89.4%). The rapid shallow breathing index (RSBI) (P < 0.001), maximum inspiratory pressure (P = 0.014), and maximum expiratory pressure (P = 0.004) of the successful group were significant while preparing to wean. The area under the receiver operating characteristic curve for the RSBI was 0.804, which was considered excellent discrimination.

Conclusion

The RSBI predicted successful weaning from NIV in patients with AECOPD with hypercapnic respiratory failure. This index may be useful for selecting patients with AECOPD that are suitable for NIV weaning.

ISHLT consensus document on lung transplantation in patients with connective tissue disease: Part II: Cardiac, surgical, perioperative, operative, and post-operative challenges and management statements

Patients with connective tissue disease (CTD) present unique surgical, perioperative, operative, and postoperative challenges related to the often underlying severe pulmonary hypertension and right ventricular dysfunction. The International Society for Heart and Lung Transplantation-supported consensus document on lung transplantation in patients with CTD standardization addresses the surgical challenges and relevant cardiac involvement in the perioperative, operative, and postoperative management in patients with CTD.

Flow Index: a novel, non-invasive, continuous, quantitative method to evaluate patient inspiratory effort during pressure support ventilation

Background

The evaluation of patient effort is pivotal during pressure support ventilation, but a non-invasive, continuous, quantitative method to assess patient inspiratory effort is still lacking. We hypothesized that the concavity of the inspiratory flow-time waveform could be useful to estimate patient’s inspiratory effort. The purpose of this study was to assess whether the shape of the inspiratory flow, as quantified by a numeric indicator, could be associated with inspiratory effort during pressure support ventilation.

Methods

Twenty-four patients in pressure support ventilation were enrolled. A mathematical relationship describing the decay pattern of the inspiratory flow profile was developed. The parameter hypothesized to estimate effort was named Flow Index. Esophageal pressure, airway pressure, airflow, and volume waveforms were recorded at three support levels (maximum, minimum and baseline). The association between Flow Index and reference measures of patient effort (pressure time product and pressure generated by respiratory muscles) was evaluated using linear mixed effects models adjusted for tidal volume, respiratory rate and respiratory rate/tidal volume.

Results

Flow Index was different at the three pressure support levels and all group comparisons were statistically significant. In all tested models, Flow Index was independently associated with patient effort (p < 0.001). Flow Index prediction of inspiratory effort agreed with esophageal pressure-based methods.

Conclusions

Flow Index is associated with patient inspiratory effort during pressure support ventilation, and may provide potentially useful information for setting inspiratory support and monitoring patient-ventilator interactions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03624-3.

Patient-ventilator asynchrony as a predictor of weaning failure in mechanically ventilated COPD patients

Background

Patient-ventilator asynchrony is a common problem in mechanically ventilated patients. It is associated with adverse effects including increased work of breathing, patient discomfort, increased need for sedation, prolonged mechanical ventilation, weaning difficulties, and weaning failure. The purpose of the present was to describe patient-ventilator asynchrony and its impact on weaning outcomes in mechanically ventilated chronic obstructive pulmonary disease (COPD) patients.

Results

One hundred mechanically ventilated COPD patients were enrolled in this prospective study. Weaning failure (need of NIV or reintubation within 48 h) was noticed in 27 (27%) patients while 73 (73%) patients had successful weaning. Patients with failed weaning had significantly higher asynchrony index (A.I) and ineffective trigger index (ITI) in comparison with those with successful weaning (7.69 ± 3.71, 3.46 ± 2.59 versus 6.27 ± 3.14, 2.47 ± 2.08, respectively; P value< 0.04). Data were expressed as mean ± standard deviation.

Conclusion

High asynchrony index and high ineffective trigger index may be early predictors of weaning failure in mechanically ventilated COPD patients.

Does Standard Physical Therapy Increase Quadriceps Strength in Chronically Ventilated Patients? A Pilot Study

OBJECTIVES

Physical therapy is standard care for mechanically ventilated patients, but there is no evidence, using nonvolitional, objective measurements, that physical therapy increases muscle strength in this population. The present study tested the hypothesis that 2 weeks of standard, conventional physical therapy provided at a ventilator weaning facility would increase quadriceps strength in mechanically ventilated patients.

DESIGN

Prospective observational study.

SETTING

Ventilator weaning unit.

PATIENTS

Patients who were transferred from an acute care hospital because of failure to wean from mechanical ventilation and who were receiving physical therapy as prescribed by facility staff.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We employed a novel, nonvolitional objective technique, quadriceps twitch force generation in response to femoral nerve magnetic stimulation, to assess leg strength before and after 2 weeks of conventional physical therapy. The duration and specific exercises provided to patients were also recorded. In a subset of patients, we measured muscle activation intensity using wireless electromyogram recordings. Indices of respiratory function (maximum inspiratory pressure generation and the rapid shallow breathing index) were also assessed. Patients' responses to 2 weeks of physical therapy were poor; on average, quadriceps twitch fell by -1.02 ± 0.71 Newtons. Neither physical therapy duration nor specific forms of exercise were identified to positively impact quadriceps twitch. Electromyogram recordings indicated that during training, muscle activation was poor. Consequently, therapists spent substantial time performing exercises that elicited little muscle activation. Physical therapy did not improve respiratory function.

CONCLUSIONS

Standard physical therapy delivered in a ventilator weaning facility failed to improve quadriceps leg strength in a majority of mechanically ventilated patients. The fact that mechanically ventilated patients fail to achieve high levels of muscle activation during physical therapy provides a potential explanation as to why physical therapy may often be ineffective. We speculate that use of novel methods which increase muscle activation during exercise may improve responses of mechanically ventilated patients to physical therapy.

Physiological changes and compensatory mechanisms by the action of respiratory muscles in a porcine model of phrenic nerve injury

Phrenic nerve damage may occur as a complication of specific surgical procedures, prolonged mechanical ventilation, or physical trauma. The consequent diaphragmatic paralysis or dysfunction can lead to major complications. The purpose of this study was to elucidate the role of the nondiaphragmatic respiratory muscles during partial or complete diaphragm paralysis induced by unilateral and bilateral phrenic nerve damage at different levels of ventilatory pressure support in an animal model. Ten pigs were instrumented, the phrenic nerve was exposed from the neck, and spontaneous respiration was preserved at three levels of pressure support, namely, high, low, and null, at baseline condition, after left phrenic nerve damage, and after bilateral phrenic nerve damage. Breathing pattern, thoracoabdominal volumes and asynchrony, and pressures were measured at each condition. Physiological breathing was predominantly diaphragmatic and homogeneously distributed between right and left sides. After unilateral damage, the paralyzed hemidiaphragm was passively dragged by the ipsilateral rib cage muscles and the contralateral hemidiaphragm. After bilateral damage, the drive to and the work of breathing of rib cage and abdominal muscles increased, to compensate for diaphragmatic paralysis, ensuing paradoxical thoracoabdominal breathing. Increasing level of pressure support ventilation replaces this muscle group compensation. When the diaphragm is paralyzed (unilaterally and/or bilaterally), there is a coordinated reorganization of nondiaphragmatic respiratory muscles as compensation that might be obscured by high level of pressure support ventilation. Noninvasive thoracoabdominal volume and asynchrony assessment could be useful in phrenic nerve-injured patients to estimate the extent and type of inspiratory muscle dysfunction.NEW & NOTEWORTHY This was the first (to our knowledge) implanted porcine model of phrenic nerve injury with a detailed multidimensional analysis of different degrees of diaphragmatic paralysis (unilateral and bilateral). Noninvasive thoracoabdominal volume and asynchrony assessment was shown to be useful in estimating the extent of diaphragmatic dysfunction and the consequent coordinated reorganization of nondiaphragmatic respiratory muscles. High level of pressure support ventilation was proved to obscure the interaction and compensation of respiratory muscles to deal with phrenic nerve injury.

A Reassessment of Weaning Parameters in Patients With Spontaneous Intracerebral Hemorrhage

Background and purpose

Patients with spontaneous intracerebral haemorrhage have significant morbidity and mortality. One aspect of their care is the need for mechanical ventilation. Extubating a patient safely and efficiently is important in advancing their care; however, traditional extubation criteria using the rapid shallow breathing index and negative inspiratory force do not predict success in these patients as well as they do in other intubated patients. This study aimed to evaluate these criteria in patients with spontaneous intracerebral haemorrhage to improve the extubation success rate.

Methods

We conducted a retrospective chart review of patients with spontaneous intracerebral haemorrhage (sICH) who underwent spontaneous breathing trials from 2018 to 2020. Twenty-nine patients met the inclusion criteria, and of these 29, 20 had a trial of extubation. Rapid shallow breathing index (RSBI), negative inspiratory force (NIF), and cuff leak were recorded to analyze breathing parameters at the time of extubation. Patients who required reintubation were noted.

Results

All trials of extubation required a cuff leak. Using RSBI, patients with values <105 or <85, as the only other extubation criteria, were associated with a 70.6% and 71.4% success rate, respectively. With RSBI <105 and NIF <-25 cm water, the success rate was 88.9%. Any patient with a cuff leak that had a NIF <-30 had a success rate of 100%, regardless of RSBI.

Conclusion

The RSBI was not a reliable isolated measure to predict 100% extubation success. Using a NIF <-30 predicts a 100% extubation success rate if a cuff leak is present. This demonstrates that the NIF may be a more useful metric in sICH patients, as it accounts for patient participation and innate ability to draw a breath spontaneously. Future studies are warranted to evaluate further and optimize the extubation criteria in these patients.

Cough peak flow to predict the extubation outcome: Comparison between three cough stimulation methods

Objectives

The purpose of this study was to compare the predictive value of three cough peak flow (CPF) maneuvers in predicting the extubation outcome in a cohort of mechanically ventilated subjects.

Methods

Eighty-one mechanically ventilated subjects who succeeded in the spontaneous breathing trial were included. In a randomized order, CPF was stimulated and measured using three methods: voluntary command (V_CPF), tracheal saline instillation (S_CPF), and mechanical stimulation with a catheter (C_CPF). Additionally, CPF was measured 20 min after the extubation (PE_CPF). The diagnostic accuracy of the CPF methods in relation to the extubation outcome was measured using the receiver operating characteristic (ROC) curve. ROC curve results were compared using the Hanley and McNeil method.

Results

The three methods presented high accuracy in predicting the extubation outcome (V_CPF = 0.89, S_CPF = 0.93, and C_CPF = 0.90), without statistically significant differences between them (V_CPF vs. S_CPF, p = 0.14; V_CPF vs. C_CPF, p = 0.84; S_CPF vs. C_CPF, p = 0.13). The optimum cutoff values were V_CPF = 45 L/min, S_CPF = 60 L/min, and C_CPF = 55 L/min. PE_CPF also showed high accuracy in predicting the extubation outcome (AUC = 0.95; cutoff = 75 L/min).

Conclusions

In mechanically ventilated and cooperative subjects, there is no difference in the accuracy of CPF measured voluntarily, with stimulation using saline or by catheter stimulation in predicting the reintubation. CPF recording after endotracheal tube removal has high accuracy to predict the extubation outcome.

Disease specific thresholds for determining extubation readiness: The optimal negative inspiratory force for chronic obstructive pulmonary disease patients

Objectives:

The negative inspiratory force (NIF) has been used to help clinicians predict a patient's likelihood of successful liberation from mechanical ventilation (MV). However, the utility of the traditional threshold of ≤−30 cmH ₂O may not be appropriate for patients with chronic obstructive pulmonary disease (COPD). This study aims to define the optimal predictive NIF threshold for COPD patients.

Methods:

A prospective-observational multi-center study was conducted in intensive care units of six academic medical centers. All patients had COPD and were intubated for hypercapnic respiratory failure. The process of weaning from MV was conducted according to the defined hospital protocol. NIF was measured after 120 min of spontaneous breathing trial (SBT). The sensitivity, specificity, positive, and negative predictive value (PPV, NPV), positive and negative likelihood ratios (LR+, LR−) were calculated, and the diagnostic accuracy recorded.

Results:

A total of 90 patients with COPD (39 males and 51 females) were included. Of these, 43 patients (47.8%) were successfully extubated whereas 47 patients (52.2%) failed SBT or required re-intubation (P = 0.654). The threshold value of ≤−25 cmH₂O offered the optimal performance in COPD patients: area under the receiver operating characteristic (ROC) curves ROC curves 0.836, sensitivity 95.0%, specificity 86.0%, PPV 84.4%, and NPV 95.6%., LR+ 6.79, LR− 0.06, and the diagnostic accuracy 90.7%.

Conclusions:

In mechanically ventilated COPD patients with hypercapnic respiratory failure, the NIF threshold of ≤−25 cmH₂O was a moderate-to-good predictor for successful ventilator liberation, and outperforms the traditional threshold of ≤−30 cmH₂O.

Clinical recommendations for cardiopulmonary exercise testing in children with respiratory diseases

INTRODUCTION

Cardiopulmonary exercise testing (CPET) quantitates and qualitates the integrated physiological response of a person to incremental exercise and provides additional information compared to static lung function tests alone.

AREAS COVERED

This review covers rationale for the use of CPET parameters beyond the usual parameters like peak oxygen uptake and peak minute ventilation in children with respiratory disease.

EXPERT OPINION

CPET provides a wealth of data from rest, submaximal and maximal exercise and data during recovery from exercise. In this review, an interpretative approach is described for analyzing CPET data in children with respiratory disease.

Pre-extubation functional residual capacity and risk of extubation failure among patients with hypoxemic respiratory failure

Hypoxemic respiratory failure is usually accompanied with a certain extent of consolidation and alveolar derecruitment, which may still be present even after the patients have achieved the status of readiness to extubate. Functional residual capacity (FRC) is an indicator of lung aeration. This study aimed to evaluate whether pre-extubation FRC is associated with the risk of extubation failure in patients with hypoxemic respiratory failure. We prospectively included 92 patients intubated for hypoxemic respiratory failure. We used a technique based on a nitrogen multiple breath washout method to measure FRC before the planned extubation. The median FRC before extubation was 25 mL/kg (Interquartile range, 20–32 mL/Kg) per predicted body weight (pBW). After extubation, 20 patients (21.7%) were reintubated within 48 hours. The median FRC was higher in the extubation success group than in the extubation failure group (27 versus 21 mL/Kg, p < 0.001). Reduced FRC was associated with higher risk of extubation failure (odds ratio, 1.14 per each decreased of 1 mL/Kg of FRC/pBW, 95% CI, 1.05–1.23, p = 0.002). In conclusion, pre-extubation FRC is associated with the risk of extubation failure. Reduced FRC may be incorporated into the traditional risk factors to identify patients at high risk for extubation failure.

Electrical impedance tomography monitoring during spontaneous breathing trial: Physiological description and potential clinical utility

BACKGROUND

Readiness for mechanical ventilation (MecV) weaning and extubation is usually assessed clinically with the use of a spontaneous breathing trial (SBT), but its accuracy is limited, and the pathophysiology of weaning failure not completely elucidated. The purpose of the present study was to describe the physiological behavior of electrical impedance tomography parameters during SBT and to propose additional variables that could be helpful in defining weaning/extubation outcome.

METHODS

From December 2015 to January 2017, all subjects who remained under MecV with an orotracheal tube for more than 24 hours and who were submitted to SBT both in pressure-support ventilation (PSV) or T-tube were included in the study. Both clinical and impedance parameters were collected immediately before as well as during SBT.

RESULTS

Forty-two subjects were included in the final analysis. For subjects submitted to SBT in PSV, none of the impedance parameters added significant information regarding weaning outcomes. For subjects submitted to a T-tube SBT, a significant and progressive decrease in end-expiratory lung impedance (dEELI) was observed, which was more prominent in subjects who clinically failed the SBT. These subjects had a significant rapid shallow breathing index at the end of SBT.

CONCLUSIONS

dEELI was a potentially useful parameter in the evaluation of MecV weaning outcome when abrupt lung depressurization was induced during SBT in our study. The degree of dEELI decrease was probably related to the magnitude of lung derecruitment, which seems to play a key role in the MecV weaning outcome.

A narrative review of diaphragm ultrasound to predict weaning from mechanical ventilation: where are we and where are we heading?

Background

The use of ultrasound to visualize the diaphragm is well established. Over the last 15 years, certain indices of diaphragm function, namely diaphragm thickness, thickening fraction and excursion have been established for mechanically ventilated patients to track changes in diaphragm size and function over time, to assess and diagnose diaphragmatic dysfunction, and to evaluate if these indices can predict successful liberation from mechanical ventilation. In the last 2 years, three meta-analyses and a systematic review have assessed the usability of diaphragmatic ultrasound to predict successful weaning. Since then, further data have been published on the topic.

Conclusions

The aim of this narrative review is to briefly describe the common methods of diaphragmatic function assessment using ultrasound techniques, before summarizing the major points raised by the recent reviews. A narrative summary of the most recent data will be presented, before concluding with a brief discussion of future research directions in this field.

Predictors of extubation failure after open-chest cardiac surgery based on routinely collected data. The importance of a shared interprofessional clinical assessment

BACKGROUND

Extubation failure (ExtF) is associated with prolonged hospital length of stay and mortality in adult cardiac surgery patients postoperatively. In this population, ExtF-related variables such as the arterial partial pressure of oxygen to fraction of inspired oxygen ratio (PaO₂/FiO₂), rapid shallow breathing index, cough strength, endotracheal secretions and neurological function have been sparsely researched.

AIM

To identify variables that are predictive of ExtF and related outcomes.

METHOD

Prospective observational longitudinal study. Consecutively presenting patients ( n=205) undergoing open-heart cardiac surgery and admitted to the Cardiosurgical Intensive Care Unit (CICU) were recruited. The clinical data were collected at CICU admission and immediately prior to extubation. ExtF was defined as the need to restart invasive or non-invasive mechanical ventilation while the patient was in the CICU.

RESULTS

The ExtF incidence was 13%. ExtF related significantly to hospital mortality, CICU length of stay and total hospital length of stay. The risk of ExtF decreased significantly, by 93% in patients with good neurological function and by 83% in those with a Rapid Shallow Breathing Index of ≥57 breaths/min per litre. Conversely, ExtF risk increased 27 times when the PaO₂/FiO₂ was <150 and 11 times when it was ≥450. Also, a reassuring PaO₂/FiO₂ value may hide critical pulmonary or extra-pulmonary conditions independent from alveolar function.

CONCLUSION

The decision to extubate patients should be taken after thoroughly discussing and combining the data derived from nursing and medical clinical assessments. Extubation should be delayed until the patient achieves safe respiratory, oxygenation and haemodynamic conditions, and good neurocognitive function.