Cough peak flows and extubation outcomes

Physiology and pathophysiology of mucus and mucolytic use in critically ill patients

Airway mucus is a highly specialised secretory fluid which functions as a physical and immunological barrier to pathogens whilst lubricating the airways and humifying atmospheric air. Dysfunction is common during critical illness and is characterised by changes in production rate, chemical composition, physical properties, and inflammatory phenotype. Mucociliary clearance, which is determined in part by mucus characteristics and in part by ciliary function, is also dysfunctional in critical illness via disease related and iatrogenic mechanisms. The consequences of mucus dysfunction are potentially devastating, contributing to prolonged ventilator dependency, increased risk of secondary pneumonia, and worsened lung injury. Mucolytic therapies are designed to decrease viscosity, improve expectoration/suctioning, and thereby promote mucus removal. Mucolytics, including hypertonic saline, dornase alfa/rhDNase, nebulised heparin, carbocisteine/N-Acetyl cysteine, are commonly used in critically ill patients. This review summarises the physiology and pathophysiology of mucus and the existing evidence for the use of mucolytics in critically ill patients and speculates on journey to individualised mucolytic therapy.

Clinical utility of rapid shallow breathing index in predicting successful weaning: secondary analysis of the COBRE-US trial

OBJECTIVE

To assess the predictive capacity of the Rapid Shallow Breathing Index (RSBI) for success in spontaneous breathing trials (SBT) and extubation in critically ill patients. We evaluated the association between RSBI, duration of mechanical ventilation, and ventilator-free time at 28 days.

DESIGN

Prospective multicenter observational study. Secondary analysis of the COBRE-US study.

SETTING

Intensive care unit (ICU).

PATIENTS OR PARTICIPANTS

367 patients in the ICU receiving invasive mechanical ventilation.

INTERVENTIONS

Assessment of RSBI at the end of SBT.

MAIN VARIABLES OF INTEREST

RSBI, SBT, duration of mechanical ventilation, and ventilator-free time at 28 days were evaluated.

RESULTS

367 patients in the ICU under invasive mechanical ventilation were evaluated, of whom 59.7% were male with a median age of 61 years (IQR: 49-72). A total of 456 SBT were conducted with a success rate of 76.5%. RSBI had a ROC-curve of 0.53 for SBT success and a ROC-curve of 0.48 for extubation. The Spearman correlation coefficient between RSBI and duration of ventilation was 0.117 (p = 0.026), while for ventilator-free time at 28 days, it was -0.116 (p = 0.028).

CONCLUSIONS

RSBI was not associated with success in SBT or extubation, regardless of the cutoff point used. Correlation analyses showed weak associations between RSBI and both the duration of ventilation and ventilator-free time at 28 days.

Factors related to cough strength before tracheal extubation in post-cardiac surgery patients: A cross-sectional study

BACKGROUND

Tracheal extubation failure after cardiac surgery is associated with diminished cough strength, albeit the information on cough strength in post-cardiac surgery patients is limited.

AIM

To investigate the cough strength in patients after cardiac surgery before tracheal extubation and the related influencing factors.

STUDY DESIGN

A cross-sectional study was designed, with adherence to the STROBE guidelines. The participants were 528 patients undergoing open-heart cardiac surgery who were admitted to the Cardio Surgical Centre in a tertiary hospital in Nanjing, China, from August 2022 to September 2023. Cough peak flow (CPF) ≤60 L/min set as the cut-off value for evaluating diminished cough strength before tracheal extubation. Univariate analysis and multiple linear regression analysis were used to analyse the related influencing factors.

RESULTS

The mean CPF was 130.70 ± 50.58 L/min. A total of 76 (14.4%) patients exhibited a CPF of ≤60 L/min. Multiple linear regression analysis revealed that gender (B = 14.266, t = 2.456, p = .014), inspiratory capacity (IC) (B = 0.013, t = 3.755, p < .001), preoperative CPF (B = 0.086, t = 3.903, p < .001), muscle strength (B = 12.423, t = 4.242, p < .001), preoperative exercise regimen (B = 16.716, t = 4.236, p < .001) and pain levels (B = -8.115, t = -5.794, p < .001) significantly contributed to cough strength.

CONCLUSIONS

Female gender, lower upper limb muscle strength, higher pain levels, lower preoperative CPF and IC, and the absence of systematic exercise were found to be associated with diminished cough strength.

RELEVANCE TO CLINICAL PRACTICE

Cough strength provides important auxiliary data in extubation decision-making. In addition, understanding its relevant factors can help identify the high-risk group of tracheal extubation failure and can help provide a strong theoretical basis for the development of personalized interventions.

Predictive value of cough peak flow for successful extubation in mechanically ventilated patients after craniotomy: a single-centre prospective diagnostic study

OBJECTIVES

The purpose of this study was to evaluate the predictive value of the cough peak flow (CPF) for successful extubation in postcraniotomy critically ill patients.

DESIGN

This was a single-centre prospective diagnostic study.

SETTING

The study was conducted in three intensive care units (ICUs) of a teaching hospital.

PARTICIPANTS

Postcraniotomy patients who were 18 years or older, stayed in ICU for more than 24 hours and underwent mechanical ventilation for more than 24 hours were eligible for the study. Patients were excluded if one of the following was present: no extubation attempt during the ICU stay; underwent tracheostomy without extubation attempt; pregnant or lactating women; enrolled in other clinical trials; declined to participate in the study. A total of 4879 patients were screened and 1037 were eligible for the study, among whom 785 were included in the study.

OUTCOME MEASURES

CPF, including involuntary (CPF-invol) and voluntary CPF (CPF-vol), were measured before extubation. The area under the receiver operating characteristic curve (AUC) was calculated to explore the diagnostic accuracy of CPF in predicting successful extubation.

RESULTS

There were 641 successful extubation cases (81.7%). The AUC of CPF-invol for predicting successful extubation was 0.810 (95% CI 0.766 to 0.854), with a cut-off value of 63.2 L/min, a sensitivity of 87.4% and a specificity of 66.7%. For conscious patients, the AUC of CPF-invol for the prediction of successful extubation was 0.849 (95% CI 0.794 to 0.904), with a cut-off value of 63.2 L/min and the AUC of CPF-vol was 0.756 (95% CI 0.696 to 0.817), with a cut-off value of 68.2 L/min.

CONCLUSIONS

The CPF was much higher in patients with successful extubation than that in patients with failed extubation. CPF might be valuable for the prediction of extubation outcomes in postcraniotomy critically ill patients. Multicentre studies could be carried out to further validate the results of this study.

TRIAL REGISTRATION NUMBER

NCT04000997.

End-tidal carbon dioxide during spontaneous breathing trial to predict extubation failure: A prospective observational study

Despite advances in weaning protocols, extubation failure (EF) is associated with poor outcomes. Many predictors of EF have been proposed, including hypercapnia at the end of the spontaneous breathing test (SBT). However, performing arterial blood gases at the end of SBT is not routinely recommended, whereas end-tidal carbon dioxide (EtCO2) can be routinely monitored during SBT. We aimed to evaluate the clinical utility of EtCO2 to predict EF. Patients undergoing planned extubation were eligible. Non-inclusion criteria were tracheostomy and patients extubated after successful T-tube SBT. We recorded clinical data and EtCO2 in 189 patients during a successful one-hour low pressure support SBT. EtCO2 measured before successful SBT was lower in patients with EF compared to those with successful extubation (27 [24-29] vs 30 [27-47] mmHg, p = 0.02), while EtCO2 measured at five minutes and at the end of the SBT was not different between the two groups (26 [22-28] vs. 29 [28-49] mmHg, p = 0.06 and 26 [26-29] vs. 29 [27-49] mmHg, p = 0.09, respectively). Variables identified by multivariable analysis as independently associated with EF were acute respiratory failure as the cause of intubation and ineffective cough. Our study suggests that recording EtCO2 during successful SBT appears to have limited predictive value for EF.

Predictors of weaning failure in ventilated intensive care patients: a systematic evidence map

BACKGROUND

Ventilator weaning is of great importance for intensive care patients in order to avoid complications caused by prolonged ventilation. However, not all patients succeed in weaning immediately. Their spontaneous breathing may be insufficient, resulting in extubation failure and the subsequent need for reintubation. To identify patients at high risk for weaning failure, a variety of potential predictors has already been examined in individual studies and meta-analyses over the last decades. However, an overview of all the predictors investigated is missing.

AIM

To provide an overview of empirically investigated predictors for weaning failure.

METHODS

A systematic evidence map was developed. To this end, we conducted a systematic search in the Medline, Cochrane, and CINAHL databases in December 2023 and added a citation search and a manual search in June 2024. Studies on predictors for weaning failure in adults ventilated in the intensive care unit were included. Studies on children, outpatients, non-invasive ventilation, or explanatory factors of weaning failure were excluded. Two reviewers performed the screening and data extraction independently. Data synthesis followed an inductive approach in which the predictors were thematically analyzed, sorted, and clustered.

RESULTS

Of the 1388 records obtained, 140 studies were included in the analysis. The 112 prospective and 28 retrospective studies investigated a total of 145 predictors. These were assigned to the four central clusters 'Imaging procedures' (n = 22), 'Physiological parameters' (n = 61), 'Scores and indices' (n = 53), and 'Machine learning models' (n = 9). The most frequently investigated predictors are the rapid shallow breathing index, the diaphragm thickening fraction, the respiratory rate, the P/F ratio, and the diaphragm excursion.

CONCLUSION

Predictors for weaning failure are widely researched. To date, 145 predictors have been investigated with varying intensity in 140 studies that are in line with the current weaning definition. It is no longer just individual predictors that are investigated, but more comprehensive assessments, indices and machine learning models in the last decade. Future research should be conducted in line with international weaning definitions and further investigate poorly researched predictors. Registration, Protocol: https://doi.org/10.17605/OSF.IO/2KDYU.

Effect of prophylactic noninvasive oxygen therapy after planned extubation on extubation failure in high-risk patients: a retrospective propensity score-matched cohort study

Background

Extubation failure (EF) is common in the intensive care unit (ICU) and is associated with poor prognosis, especially in high-risk patients. However, the efficacy of prophylactic noninvasive oxygen therapy (NIT), including noninvasive ventilation (NIV) and high-flow nasal cannula (HFNC), in reducing EF in high-risk patients remains controversial. Therefore, we aimed to evaluate the effect of post-extubation prophylactic NIT on EF in high-risk patients.

Methods

This was a retrospective observational study conducted in the ICU from March 2018 to December 2023. We included adult patients at high risk for reintubation who were mechanically ventilated for over 24 h and successfully passed the spontaneous breathing trial (SBT). Immediately after extubation, patients underwent NIT or conventional oxygenation therapy (COT). The primary outcome was the EF rate within 7 days after extubation.

Results

There were 440 patients in the NIT group and 274 in the COT group. After propensity-score matching, 227 subjects were enrolled in each group. NIT reduced the rate of EF (18.0% vs. 34.3%, p < 0.001) and reintubation (10.5% vs. 18.2% p = 0.003) compared with COT, which was confirmed in propensity-matched cohort (17.6% vs. 32.2%, p < 0.001; 11.5% vs. 19.8%, p = 0.014). Multivariate logistic regression analysis indicated that prophylactic NIT (p = 0.001) and higher ROX index (p = 0.022) were associated with reduced risk of EF. While higher fluid balance (p = 0.013), higher RSBI (p < 0.001), and the occurrence of delirium (p = 0.032) may be the risk factors for EF. Subgroup analysis showed that post-extubation NIT was more effective in elderly patients, and HFNC was non-inferior to NIV in reducing EF. While HFNC had a tendency to reduce the incidence of delirium.

Conclusion

Post-extubation prophylactic NIT is effective in reducing EF in high-risk patients, especially in the elderly patients. HFNC is an alternative treatment to NIV. Fluid balance, RSBI, ROX index, and delirium are associated with the occurrence of EF.

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

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

Assessing the reproducibility and predictive value of objective cough measurement for successful withdrawal of invasive ventilatory support in adult patients

BACKGROUND

Utilizing clinical tests, such as objective cough measurement, can assist in predicting the success of the weaning process in critically ill patients.

METHODS

A multicenter observational analytical study was conducted within a prospective cohort of patients recruited to participate in COBRE-US. We assessed the capability of objective cough measurement to predict the success of the spontaneous breathing trial (SBT) and extubation. Intra- and inter-observer reproducibility of the cough test and was evaluated using the intraclass correlation coefficient (ICC) and Cohen's weighted kappa. We used receiver operating characteristic curves (ROC-curve) to evaluate the predictive ability of objective cough measurement.

RESULTS

We recruited 367 subjects who were receiving invasive mechanical ventilation. A total of 451 objective cough measurements and 456 SBTs were conducted. A significant association was found between objective cough measurement and successful SBT (OR: 1.68; 95% CI 1.48-1.90; p = 0.001). The predictive capability of the objective cough test for SBT success had a ROC-curve of 0.58 (95% CI: 0.56-0.61). Objective cough measurement to predict successful extubation had a ROC-curve of 0.61 (95% CI: 0.56-0.66). The intraobserver reproducibility exhibited an ICC of 0.94 (95% CI: 0.89-0.96; p < 0.001), while the interobserver reproducibility demonstrated an ICC of 0.72 (95% CI: 0.51-0.85; p < 0.001). The intraobserver agreement, assessed using Cohen's weighted kappa was 0.94 (95% CI: 0.93-0.99; p < 0.001), whereas the interobserver agreement was 0.84 (95% CI: 0.67 - 0.10; p < 0.001).

CONCLUSIONS

The objective measurement of cough using the method employed in our study demonstrates nearly perfect intra-observer reproducibility and agreement. However, its ability to predict success or failure in the weaning process is limited.

Effects of mechanical insufflation-exsufflation on ventilator-free days in intensive care unit subjects with sputum retention; a randomized clinical trial

BACKGROUND

Mechanical insufflation-exsufflation (MI-E) facilitates extubation. However, its potential to reduce the duration of ventilator use remains unclear. Therefore, the present study investigated whether the use of MI-E shortened the duration of mechanical ventilation in patients with high sputum retention.

METHODS

A randomized open-label trial was conducted at a single intensive care unit (ICU) in Japan between November 2017 and June 2019. Ventilated subjects requiring suctioning at least once every hour due to sputum retention were randomly assigned to the MI-E group or conventional care group. The primary endpoint was the number of ventilator-free days on day 28. Secondary endpoints were ventilator days in surviving subjects, the length of ICU stay, and mortality and tracheostomy rates among survivors.

RESULTS

Forty-eight subjects (81% males) with a median age of 72 years (interquartile range [IQR], 65-85 years) were enrolled. There were 27 subjects in the MI-E group and 21 in the control group. The median number of ventilator-free days was 21 (IQR, 13-24) and 18, respectively (IQR, 0-23) (P = .38). No significant differences were observed in the ICU length of stay (median, 10 days (IQR, 7-12) vs 12 days (IQR, 6-15); P = .31), mortality rate (19% vs 15%; odds ratio [OR], 1.36 [0.28-6.50]; P = .69), or tracheostomy rate among survivors (14% vs 28%; OR, 0.40 [0.08-1.91]; P = .25).

CONCLUSION

In ventilated subjects in the ICU with high sputum retention, the use of MI-E did not significantly increase the number of ventilator-free days over that with conventional care.

Cough flows as a criterion for decannulation of autonomously breathing patients with tracheostomy tubes

BACKGROUND

Adequate cough or exsufflation flow can indicate an option for safe tracheostomy decannulation to noninvasive management. Cough peak flow via the upper airways with the tube capped is an outcome predictor for decannulation readiness in patients with neuromuscular impairment. However, this threshold value is typically measured with tracheotomy tube removed, which is not acceptable culturally in China. The aim of this study was to assess the feasibility and safety of using cough flow measured with tracheostomy tube and speaking valve (CFSV) > 100 L/min as a cutoff value for decannulation.

STUDY DESIGN

Prospective observational study conducted between January 2019 and September 2022 in a tertiary rehabilitation hospital.

METHODS

Patients with prolonged tracheostomy tube placement were referred for screening. Each patient was assessed using a standardized tracheostomy decannulation protocol, in which CFSV greater than 100 L/min indicated that the patients' cough ability was sufficient for decannulation. Patients whose CFSV matched the threshold value and other protocol criteria were decannulated, and the reintubation and mortality rates were followed-up for 6 months.

RESULTS

A total of 218 patients were screened and 193 patients were included. A total of 105 patients underwent decannulation, 103 patients were decannulated successfully, and 2 patients decannulated failure, required reinsertion of the tracheostomy tube within 48 h (failure rate 1.9%). Three patients required reinsertion or translaryngeal intubation within 6 months.

CONCLUSIONS

CFSV greater than 100 L/min could be a reliable threshold value for successful decannulation in patients with various primary diseases with a tracheostomy tube.

TRIAL REGISTRATION

This observational study was not registered online.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Static Respiratory System Compliance as a Predictor of Extubation Failure in Patients with Acute Respiratory Failure

PURPOSE

Ventilator weaning protocols rely in part on objective indices to best predict extubation failure in the critically ill. We investigated static respiratory system compliance (RC) as a predictor of extubation failure, in comparison to extubation readiness using rapid shallow breathing index (RSBI).

MATERIAL AND METHODS

This was a cross-sectional, multi-institutional study of mechanically ventilated patients admitted between 12/01/2017 and 12/01/2019. All patients older than 18 years with a documented spontaneous breathing trial and extubation trial were included. RC and RSBI were calculated prior to the extubation trial. The primary outcome was extubation failure-defined as need for reintubation within 72 h from time of extubation.

RESULTS

Of the 2263 patients, 55.8% were males with a mean age of 68 years. The population consisted mostly of Caucasians (73%) and African Americans (20.4%). 274 (12.1%) patients required reintubation within 72 h. On multivariate logistic regression after adjusting for age, sex, body mass index (BMI), admission Sequential Organ Failure Assessment (SOFA) score, number of ventilator days, and the P/F ratio on the day of extubation, RC remained the strongest predictor for extubation failure at 24 h (aOR 1.45; 95% CI 1.00-2.10) and 72 h (aOR 1.58; 95% CI 1.15-2.17). There was no significant association between RSBI and extubation failure at 24 (aOR 1.00; 95% CI 0.99-1.01) or at 72 h (aOR 1.00; 95% CI 0.99-1.01).

CONCLUSION

RC measured on the day of extubation is a promising physiological discriminant to potentially risk stratify patients with acute respiratory failure for extubation readiness. We recommend further validation studies in prospective cohorts.

Predictors of extubation failure in neurocritical patients: A systematic review

OBJECTIVE

The objective of this study was to identify predictors of extubation failure in neurocritical patients.

METHODS

This was systematic review performed through a bibliographic search of the databases PubMed/Medline, Lilacs, SciELO, and Web of Science, from February 2020 to October 2021. Cohort studies that investigated the predictors of extubation failure were included, defined as the need for reintubation within 48 h after extubation, in adult neurocritical patients. The risk-of-bias assessment was performed using the Newcastle-Ottawa Scale, for cohort studies.

RESULTS

Eight studies, totaling 18 487 participants, were included. A total of 15 predictors for extubation failure in neurocritical patients have been identified. Of these, four were the most frequent: low score on the Glasgow Coma Scale (motor score ≤5, 8T-10T), female gender, time on mechanical ventilation (≥7 days, ≥ 10 days), and moderate or large secretion volume.

CONCLUSIONS

In addition to the conventional parameters of weaning and extubation, other factors, such as a low score on the Glasgow Coma Scale, female gender, mechanical ventilation time, and moderate or large secretion volume, must be taken into account to prevent extubation failure in neurocritical patients in clinical practice.

The risk factors of reintubation in intensive care unit patients on mechanical ventilation: A systematic review and meta-analysis

OBJECTIVE

To assess risk factors of reintubation in intensive care unit patients on mechanical ventilation.

METHODOLOGY

We conducted a systematic review of literature (inception to May 2022) and a meta-analysis. Data are reported as pooled odds ratios for categorical variables and mean differences for continuous variables.

RESULTS

A total of 2459 studies were retrieved of which 38 studies were included in a meta-analysis involving 22,304 patients. Risk factors identified were: older age, higher APACHE II scores, COPD, pneumonia, shock, low SaO₂, low PaO₂, low PaO₂/FiO₂, low hemoglobin, low albumin, high brain natriuretic peptide, low pH, high respiratory rate, low tidal volume, a higher rapid shallow breathing index, a lower vital capacity, a higher number of spontaneous breathing trials, prolonged length of mechanical ventilation, weak cough, a reduced patient's cough peak flow and positive cuff leak test. Subgroup analysis showed that risk factors substantially overlap when reintubation was considered within 48 hours or within 72 hours after extubation.

CONCLUSIONS

We identified 21 factors associated with increased risk for reintubation. These allow to recognize the patient at high risk for reintubation at an early stage. Future studies may combine these factors to develop comprehensive predictive algorithms allowing appropriate vigilance.

Underweight predicts extubation failure after planned extubation in intensive care units

BACKGROUND

Body weight is associated with different physiological changes and the association between weight and mortality in critical care setting had been discussed before. In this study, we investigated the linkage between underweight and post-extubation failure in mechanical ventilated patients in critical setting.

METHODS

This is a retrospective cohort study including patients who were admitted to medical or surgical intensive care units (ICU) between June 2016 and July 2018 and had received endotracheal intubation for more than 72 hours. Those who passed spontaneous breathing trial and underwent a planned extubation were enrolled. Extubation failure was defined as those who required reintubation within the first 72 hours for any reasons. The probability of extubation failure was calculated. Demographic and clinical characteristics were recorded. Multivariate logistic regression models were then used to determine the potential risk factors associated with extubation failure.

RESULTS

Overall, 268 patients met the inclusion criteria and were enrolled in our study for analysis. The median age of included patients was 67 years (interquartile range, 55-80 years) with 65.3% being male; 63.1% of the patients were included from medical ICU. The proportion of extubation failure in our cohort was 7.1% (19/268; 95% confidence interval [CI], 4.3-10.9%). Overall, underweight patients had the highest risk of extubation failure (8/50), as compared with normoweight (9/135) and overweight patients (2/83). In the multivariate analysis, being underweight (adjust OR [aOR], 3.80, compared to normoweight; 95% CI, 1.23-11.7) and lower maximal inspiratory airway pressure (aOR per one cmH2O decrease, 1.05; 95% CI 1.00-1.09) remained significantly associated with extubation failure.

CONCLUSION

In our study, being underweight and lower maximal inspiratory airway pressure was associated with post-extubation respiratory failure after a planned extubation.

Liberation From Mechanical Ventilation in the Cardiac Intensive Care Unit

The prevalence of respiratory failure is increasing in the contemporary cardiac intensive care unit (CICU) and is associated with a significant increase in morbidity and mortality. For patients that survive their initial respiratory decompensation, liberation from invasive mechanical ventilation (IMV) and the decision to extubate requires careful clinical assessment and planning. Therefore, it is essential for the CICU clinician to know how to assess and manage the various stages of IMV liberation, including ventilator weaning, evaluation of extubation readiness, and provide post-extubation care. In this review, we provide a comprehensive approach to liberation from IMV in the CICU, including cardiopulmonary interactions relative to withdrawal from positive pressure ventilation, evaluation of readiness for and assessment of spontaneous breathing trials, sedation management to optimize extubation, strategies for patients at a high risk for extubation failure, and tracheostomy in the cardiovascular patient.

Machine learning for predicting successful extubation in patients receiving mechanical ventilation

Ventilator liberation is one of the most critical decisions in the intensive care unit; however, prediction of extubation failure is difficult, and the proportion thereof remains high. Machine learning can potentially provide a breakthrough in the prediction of extubation success. A total of seven studies on the prediction of extubation success using machine learning have been published. These machine learning models were developed using data from electronic health records, 8–78 features, and algorithms such as artificial neural network, LightGBM, and XGBoost. Sensitivity ranged from 0.64 to 0.96, specificity ranged from 0.73 to 0.85, and area under the receiver operating characteristic curve ranged from 0.70 to 0.98. The features deemed most important included duration of mechanical ventilation, PaO₂, blood urea nitrogen, heart rate, and Glasgow Coma Scale score. Although the studies had limitations, prediction of extubation success by machine learning has the potential to be a powerful tool. Further studies are needed to assess whether machine learning prediction reduces the incidence of extubation failure or prolongs the duration of ventilator use, thereby increasing tracheostomy and ventilator-related complications and mortality.

Detection of pharyngeal perforation during fiberoptic endoscopic evaluation of swallowing in a person with cervical spinal cord injury in the intensive care unit: a case report

Endotracheal tube insertion and mechanical ventilation are indicated in spinal cord injury patients; however, dysphagia can occur after extubation. The resultant complications of dysphagia may increase the length of hospital stay and mortality. Therefore, dysphagia should be evaluated after extubation. This case report introduces a rare case of finding pharyngeal perforation during the fiberoptic endoscopic evaluation of swallowing (FEES) in patients with cervical spine injuries in the intensive care unit. A 71-year-old male patient met with a road traffic accident. The patient underwent C3-4 posterior fusion and C3-4 anterior cervical discectomy and fusion. After successful extubation, the patient underwent FEES to assess swallowing function. During FEES, the metallic plate was found to be exposed through mucosal erosion, and swelling was observed at the surgical site at the hypopharynx. The nasogastric tube was removed to prevent secondary damage and infection at the operation site and the patient was received conservative therapy. The FEES endoscope machine is portable so it can be easily applied at the bedside to intensive care unit patients. In addition, FEES allows the identification of anatomical abnormalities of the oropharynx and abnormalities of vocal cord. Thus, it is recommended to do FEES to check anatomical abnormalities as well as dysphagia in patients in the intensive care unit.

Use of mechanical insufflation exsufflation and manual techniques in an intubated adult with COVID-19 positioned in prone-A case study

BACKGROUND AND PURPOSE

The therapeutic benefits of prone positioning have been described over the last 50 years culminating in a systematic review supporting this management strategy for patients with severe hypoxaemic respiratory failure. Early work detailing treatment approaches for COVID-19 have advocated the use of prone positioning. Limited data exists regarding physiotherapy intervention in patients with COVID-19 owing to the recent emergence of this novel disease. Despite the acknowledged beneficial effects of physiotherapy on secretion clearance and lung recruitment in the general critical care population, there is a lack of evidence pertaining to physiotherapeutic intervention for acutely unwell intubated adults in prone lying.

METHODS

This case study report follows the CARE case report guidelines. One patient with COVID-19 pneumonitis who underwent physiotherapy intervention in prone lying is discussed. Informed consent was gained from next of kin for data to be published.

RESULTS

Treatment techniques including mechanical insufflation-exsufflation in prone were feasible and well tolerated by this patient with only transient adverse effects noted. Treatment techniques assisted with secretion clearance.

DISCUSSION

Further work on safety, feasibility, and efficacy of physiotherapy intervention in patients with and without COVID-19 in prone will contribute to the evidence base on this subject.

Mucus Clearance Strategies in Mechanically Ventilated Patients

The use of airway clearance strategies as supplementary treatment in respiratory disease has been best investigated in patients with cystic fibrosis (CF) and non-cystic fibrosis bronchiectasis (NCFBE), conditions which are traditionally characterized by excessive mucus stasis and mucociliary dysfunction. A variety of airway clearance therapies both pharmacological and non-pharmacological have been shown to ameliorate disease progression in this population and have hence been assimilated into routine respiratory care. This self-propagating cycle of mucus retention and airway damage leading to chronic inflammation and infections can also be applied to patients with respiratory failure requiring mechanical ventilation. Furthermore, excessive trachea-bronchial secretions have been associated with extubation failure presenting an opportunity for intervention. Evidence for the use of adjunctive mucoactive agents and other therapies to facilitate secretion clearance in these patients are not well defined, and this subgroup still remains largely underrepresented in clinical trials. In this review, we discuss the role of mucus clearance techniques with a proven benefit in patients with CF and NCFBE, and their potential role in patients requiring mechanical ventilation while highlighting the need for standardization and adoption of mucus clearance strategies in these patient populations.

A Simple Algorithm Using Ventilator Parameters to Predict Successfully Rapid Weaning Program in Cardiac Intensive Care Unit Patients

BACKGROUND

Ventilator weaning is one of the most significant challenges in the intensive care unit (ICU). Approximately 30% of patients fail to wean, resulting in prolonged use of ventilators and increased mortality. There are numerous high-performance prediction models available today, but they require a large number of parameters to predict and are thus impractical in clinical practice.

OBJECTIVES

This study aims to create an artificial intelligence (AI) model for predicting weaning time and to identify the most simplified key predictors that will allow the model to achieve adequate accuracy with as few parameters as possible.

METHODS

This is a retrospective study of to-be-weaned patients (n = 1439) hospitalized in the cardiac ICU of Cheng Hsin General Hospital's Department of Cardiac Surgery from November 2018 to August 2020. The patients were divided into two groups based on whether they could be weaned within 24 h (i.e., "patients weaned within 24 h" (n = 1042) and "patients not weaned within 24 h" (n = 397)). Twenty-eight variables were collected including demographic characteristics, arterial blood gas readings, and ventilation set parameters. We created a prediction model using logistic regression and compared it to other machine learning techniques such as decision tree, random forest, support vector machine (SVM), extreme gradient boosting, and artificial neural network. Forward, backward, and stepwise selection methods were used to identify significant variables, and the receiver operating characteristic curve was used to assess the accuracy of each AI model.

RESULTS

The SVM [receiver operating characteristic curve (ROC-AUC) = 88%], logistic regression (ROC-AUC = 86%), and XGBoost (ROC-AUC = 85%) models outperformed the other five machine learning models in predicting weaning time. The accuracies in predicting patient weaning within 24 h using seven variables (i.e., expiratory minute ventilation, expiratory tidal volume, ventilation rate set, heart rate, peak pressure, pH, and age) were close to those using 28 variables.

CONCLUSIONS

The model developed in this research successfully predicted the weaning success of ICU patients using a few and easily accessible parameters such as age. Therefore, it can be used in clinical practice to identify difficult-to-wean patients to improve their treatment.

Reintubation Summation Calculation: A Predictive Score for Extubation Failure in Critically Ill Patients

Objective

To derive and validate a multivariate risk score for the prediction of respiratory failure after extubation.

Patients and methods

We performed a retrospective cohort study of adult patients admitted to the intensive care unit from January 1, 2006, to December 31, 2015, who received mechanical ventilation for ≥48 h. Extubation failure was defined as the need for reintubation within 72 h after extubation. Multivariate logistic regression model coefficient estimates generated the Re-Intubation Summation Calculation (RISC) score.

Results

The 6,161 included patients were randomly divided into 2 sets: derivation (n = 3,080) and validation (n = 3,081). Predictors of extubation failure in the derivation set included body mass index <18.5 kg/m² [odds ratio (OR), 1.91; 95% CI, 1.12–3.26; P = 0.02], threshold of Glasgow Coma Scale of at least 10 (OR, 1.68; 95% CI, 1.31–2.16; P < 0.001), mean airway pressure at 1 min of spontaneous breathing trial <10 cmH₂O (OR, 2.11; 95% CI, 1.68–2.66; P < 0.001), fluid balance ≥1,500 mL 24 h preceding extubation (OR, 2.36; 95% CI, 1.87–2.96; P < 0.001), and total mechanical ventilation days ≥5 (OR, 3.94; 95% CI 3.04–5.11; P < 0.001). The C-index for the derivation and validation sets were 0.72 (95% CI, 0.70–0.75) and 0.72 (95% CI, 0.69–0.75). Multivariate logistic regression demonstrated that an increase of 1 in RISC score increased odds of extubation failure 1.6-fold (OR, 1.58; 95% CI, 1.47–1.69; P < 0.001).

Conclusion

RISC predicts extubation failure in mechanically ventilated patients in the intensive care unit using several clinically relevant variables available in the electronic medical record but requires a larger validation cohort before widespread clinical implementation.

Effect of Prolonged Mechanical Ventilation on Cough Function and TRPV1 Expression

Cough is a pivotal airway protective reflex, yet the effects of prolonged mechanical ventilation (PMV) on cough function are unknown. This study compared the cough function in subjects with PMV (≥ 21 days, n = 29) and those with short-term mechanical ventilation (SMV, ≤ 7 days, n = 27). Cough reflex sensitivity was measured by capsaicin provocation concentrations after extubation. The cough strength of respiratory muscles was assessed by involuntary cough peak expiratory flow (iCPEF). The mRNA expression of transient receptor potential vanilloid 1 (TRPV1), a cough sensor activated by capsaicin, in tracheal tissues was determined. We found that cough reflex sensitivity and iCPEF were significantly lower in the PMV group than in the SMV group. The tracheal expression of TRPV1 was similar in both groups, suggesting that changes in TRPV1 expression may not be a contributing factor. Our finding regarding the cough dysfunction after PMV highlights the need to implement effective airway clearance management and rehabilitation in this population.

Frequent tracheal suctioning is associated with extubation failure in patients with successful spontaneous breathing trial: a single-center retrospective cohort study

BACKGROUND

Extubation failure, i.e., reintubation in ventilated patients, is a well-known risk factor for mortality and prolonged stay in the intensive care unit (ICU). Although sputum volume is a risk factor, the frequency of tracheal suctioning has not been validated as a predictor of reintubation. We conducted this study to examine whether frequent tracheal suctioning is a risk factor for reintubation.

PATIENTS AND METHODS

We included adult patients who were intubated for > 72 h in the ICU and extubated after completion of spontaneous breathing trial (SBT). We compared the characteristics and weaning-related variables, including the frequency of tracheal suctioning between patients who required reintubation within 24 h after extubation and those who did not, and examined the factors responsible for reintubation.

RESULTS

Of the 400 patients enrolled, reintubation was required in 51 (12.8%). The most common cause of reintubation was difficulty in sputum excretion (66.7%). There were significant differences in sex, proportion of patients with chronic kidney disease, pneumonia, ICU admission type, the length of mechanical ventilation, and ICU stay between patients requiring reintubation and those who did not. Multivariate analysis showed frequent tracheal suction (> once every 2 h) and the length of mechanical ventilation were independent factors for predicting reintubation.

CONCLUSION

We should examine the frequency of tracheal suctioning > once every 2 h in addition to the length of mechanical ventilation before deciding to extubate after completion of SBT in patients intubated for > 72 h in the ICU.

Weaning critically ill patients from mechanical ventilation: a protocol from a multicenter retrospective cohort study

BACKGROUND

Mechanical ventilation (MV) is an important lifesaving method in intensive care unit (ICU). Prolonged MV is associated with ventilator associated pneumonia (VAP) and other complications. However, premature weaning from MV may lead to higher risk of reintubation or mortality. Therefore, timely and safe weaning from MV is important. In addition, identification of the right patient and performing a suitable weaning process is necessary. Although several guidelines about weaning have been reported, compliance with these guidelines is unknown. Therefore, the aim of this study is to explore the variation of weaning in China, associations between initial MV reason and clinical outcomes, and factors associated with weaning strategies using a multicenter cohort.

METHODS

This multicenter retrospective cohort study will be conducted at 17 adult ICUs in China, that included patients who were admitted in this 17 ICUs between October 2020 and February 2021. Patients under 18 years of age and patients without the possibility for weaning will be excluded. The questionnaire information will be registered by a specific clinician in each center who has been evaluated and qualified to carry out the study.

DISCUSSION

In a previous observational study of weaning in 17 ICUs in China, weaning practices varies nationally. Therefore, a multicenter retrospective cohort study is necessary to be conducted to explore the present weaning methods used in China.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR) (No. ChiCTR2100044634).

Prognostic Value of Preoperative Peak Expiratory Flow to Predict Postoperative Pulmonary Complications in Surgical Lung Cancer Patients

Objectives

Cough impairment may lead to excessive accumulation of pulmonary secretions and increase the risk of postoperative pulmonary complications (PPCs). Peak expiratory flow (PEF) is a sensitive indicator of cough ability. We aimed to investigate the correlation between PEF and PPCs for lung cancer patients undergoing lobectomy or segmental resection for improved risk assessment.

Methods

This retrospective study assessed 560 patients with non-small cell lung cancer admitted for surgery between January 2014 to June 2016. The measurements of PEF were performed before surgery and the clinical outcomes were recorded, including PPCs, postoperative hospital stay, hospitalization costs, and other variables.

Results

Preoperative PEF was significantly lower in PPCs group compared to non-PPCs group (294.2 ± 95.7 vs. 363.0 ± 105.6 L/min, P < 0.001). Multivariable regression analysis showed that high PEF (OR=0.991, 95%CI: 0.988-0.993, P < 0.001) was an independent protective factor for PPCs. According to the receiver operating characteristic (ROC) curve, a PEF value of 250 L/min was selected as the optimal cutoff value in female patients, and 320 L/min in male patients. Patients with PEF under cutoff value of either sex had higher PPCs rate and unfavorable clinical outcomes.

Conclusions

Preoperative PEF was found to be a significant predictor of PPCs for surgical lung cancer patients. It may be beneficial to consider the cutoff value of PEF in perioperative risk assessment.

Predictive power of extubation failure diagnosed by cough strength: a systematic review and meta-analysis

Background

The predictive power of extubation failure diagnosed by cough strength varies by study. Here we summarise the diagnostic power of extubation failure tested by cough strength.

Methods

A comprehensive online search was performed to select potentially eligible studies that evaluated the predictive power of extubation failure tested by cough strength. A manual search was also performed to identify additional studies. Data were extracted to calculate the pooled sensitivity, specificity, positive likelihood ratio (LR), negative LR, diagnostic odds ratio (DOR), and area under the receiver operating characteristic curve (AUC) to evaluate the predictive power of extubation failure.

Results

A total of 34 studies involving 45 study arms were enrolled, and 7329 patients involving 8684 tests were analysed. In all, 23 study arms involving 3018 tests measured cough peak flow before extubation. The pooled extubation failure was 36.2% and 6.3% in patients with weak and strong cough assessed by cough peak flow, respectively. The pooled sensitivity, specificity, positive LR, negative LR, DOR, and AUC were 0.76 (95% confidence interval [CI]: 0.72–0.80), 0.75 (0.69–0.81), 2.89 (2.36–3.54), 0.37 (0.30–0.45), 8.91 (5.96–13.32), and 0.79 (0.75–0.82), respectively. Moreover, 22 study arms involving 5666 tests measured the semiquantitative cough strength score (SCSS) before extubation. The pooled extubation failure was 37.1% and 11.3%, respectively, in patients with weak and strong cough assessed by the SCSS. The pooled sensitivity, specificity, positive LR, negative LR, DOR, and AUC were 0.53 (95% CI: 0.41–0.64), 0.83 (0.74–0.89), 2.50 (1.93–3.25), 0.65 (0.56–0.76), 4.61 (3.03–7.01), and 0.74 (0.70–0.78), respectively.

Conclusions

Weak cough is associated with increased extubation failure. Cough peak flow is superior to the SCSS for predicting extubation failure. However, both show moderate power for predicting extubation failure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03781-5.

Handgrip strength to predict extubation outcome: a prospective multicenter trial

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Global Physiology and Pathophysiology of Cough: Part 2. Demographic and Clinical Considerations: CHEST Expert Panel Report

BACKGROUND

Cough characteristics vary between patients, and this can impact clinical diagnosis and care. The purpose of part two of this state-of-the-art review is to update the American College of Chest Physicians (CHEST) 2006 guideline on global physiology and pathophysiology of cough.

STUDY DESIGN AND METHODS

A review of the literature was conducted using PubMed and MEDLINE databases from 1951 to 2019 using prespecified search terms.

RESULTS

We describe the demographics of typical patients with cough in the clinical setting, including how cough characteristics change across age. We summarize the effect of common clinical conditions impacting cough mechanics and the physical properties of mucus on airway clearance.

INTERPRETATION

This is the second of a two-part update to the 2006 CHEST cough guideline; it complements part one on basic phenomenology of cough by providing an extended clinical picture of cough along with the factors that alter cough mechanics and efficiency in patients. A greater understanding of the physiology and pathophysiology of cough will improve clinical management.

Cough peak flow to predict extubation outcome: a systematic review and meta-analysis

Objetivo

Avaliar a utilidade do pico de fluxo da tosse para predizer o desfecho da extubação em pacientes que obtiveram sucesso no teste de respiração espontânea.

Métodos

A busca cobriu as bases de dados científicos MEDLINE^®, Lilacs, Ibecs, Cinahl, SciELO, Cochrane, Scopus, Web of Science e literatura cinzenta. Utilizaram-se os critérios Quality Assessment of Diagnostic Accuracy Studies para avaliar a qualidade da metodologia e o risco de viés dos estudos. A heterogeneidade estatística da razão de verossimilhança (LR) e razão de chance diagnóstica (RCD) do diagnóstico foram avaliadas com utilização de gráficos em floresta, teste Q de Cochran e um gráfico crosshair summary Receiver Operating Characteristic, utilizando um modelo com múltiplos pontos de corte.

Resultados

Inicialmente obteve-se, nas bases de dados, um total de 3.522 referências; dentre estas, selecionaram-se para análise qualitativa 12 estudos que incluíram 1.757 participantes. Muitos estudos apresentavam um risco de viés incerto em termos da seleção de pacientes e do fluxo e tempo. Dentre os 12 estudos incluídos, sete tinham alto risco e cinco risco incerto para o item padrão de referência. O desempenho diagnóstico do pico de fluxo da tosse para o resultado da extubação foi baixo a moderado quando se consideram os resultados de todos os estudos incluídos, com +LR de 1,360 (IC95% 1,240 - 1,530), -LR de 0,218 (IC95% 0,159 - 0,293) e razão de chance diagnóstica de 6,450 (IC95% 4,490 - 9,090). Uma análise de subgrupos que incluiu somente estudos com valores de corte entre 55 e 65 L/minuto demonstrou desempenho ligeiramente melhor, porém ainda moderado.

Conclusão

A avaliação do pico de fluxo da tosse, considerando valor de corte entre 55 e 65 L/minuto, pode ser útil como medida complementar antes da extubação. São necessários estudos com melhor delineamento para elucidar o melhor método e equipamento para registrar o pico de fluxo da tosse, assim como o melhor ponto de corte.

Changes in Respiratory Muscle Thickness during Mechanical Ventilation: Focus on Expiratory Muscles

BACKGROUND

The lateral abdominal wall muscles are recruited with active expiration, as may occur with high breathing effort, inspiratory muscle weakness, or pulmonary hyperinflation. The effects of critical illness and mechanical ventilation on these muscles are unknown. This study aimed to assess the reproducibility of expiratory muscle (i.e., lateral abdominal wall muscles and rectus abdominis muscle) ultrasound and the impact of tidal volume on expiratory muscle thickness, to evaluate changes in expiratory muscle thickness during mechanical ventilation, and to compare this to changes in diaphragm thickness.

METHODS

Two raters assessed the interrater and intrarater reproducibility of expiratory muscle ultrasound (n = 30) and the effect of delivered tidal volume on expiratory muscle thickness (n = 10). Changes in the thickness of the expiratory muscles and the diaphragm were assessed in 77 patients with at least two serial ultrasound measurements in the first week of mechanical ventilation.

RESULTS

The reproducibility of the measurements was excellent (interrater intraclass correlation coefficient: 0.994 [95% CI, 0.987 to 0.997]; intrarater intraclass correlation coefficient: 0.992 [95% CI, 0.957 to 0.998]). Expiratory muscle thickness decreased by 3.0 ± 1.7% (mean ± SD) with tidal volumes of 481 ± 64 ml (P < 0.001). The thickness of the expiratory muscles remained stable in 51 of 77 (66%), decreased in 17 of 77 (22%), and increased in 9 of 77 (12%) patients. Reduced thickness resulted from loss of muscular tissue, whereas increased thickness mainly resulted from increased interparietal fasciae thickness. Changes in thickness of the expiratory muscles were not associated with changes in the thickness of the diaphragm (R2 = 0.013; P = 0.332).

CONCLUSIONS

Thickness measurement of the expiratory muscles by ultrasound has excellent reproducibility. Changes in the thickness of the expiratory muscles occurred in 34% of patients and were unrelated to changes in diaphragm thickness. Increased expiratory muscle thickness resulted from increased thickness of the fasciae.

EDITOR’S PERSPECTIVE

The Effect of Reconnection to Mechanical Ventilation for 1 Hour After Spontaneous Breathing Trial on Reintubation Among Patients Ventilated for More Than 12 Hours: A Randomized Clinical Trial

BACKGROUND

The resting of the respiratory musculature after undergoing the spontaneous breathing trial (SBT) to prevent extubation failures in critically ill patients needs to be studied further.

RESEARCH QUESTION

Is the reconnection to mechanical ventilation (MV) for 1 h after a successful SBT able to reduce the risk of reintubation?

STUDY DESIGN AND METHODS

Randomized clinical trial conducted in four ICUs between August 2018 and July 2019. Candidates for tracheal extubation who met all screening criteria for weaning were included. After achieving success in the SBT using a T-tube, the patients were randomized to the following groups: direct extubation (DE) or extubation after reconnection to MV for 1 h (R1h). The primary outcome was reintubation within 48 h.

RESULTS

Among the 336 patients studied (women, 41.1%; median age, 59 years [interquartile range, 45-70 years]), 12.9% (22/171) in the R1h group required reintubation within 48 h vs 18.2% (30/165) in the DE group (risk difference, 5.3 [95% CI, -2.49 to 13.12]; P = .18). No differences were found in mortality, length of ICU or hospital stay, causes of reintubation, or signs of extubation failure. A prespecified exploratory analysis showed that among the 233 patients (69.3%) who were ventilated for more than 72 h, the incidence of reintubation was 12.7% (15/118) in the R1h group compared with 22.6% (26/115) observed in the DE group (P = .04).

INTERPRETATION

Reconnection to MV after a successful SBT, compared with DE, did not result in a statistically significant reduction in the risk of reintubation in mechanically ventilated patients. Subgroup exploratory findings suggest that the strategy may benefit patients who were ventilated for more than 72 h, which should be confirmed in further studies.

TRIAL REGISTRY

Brazilian Clinical Trials Registry; No.: RBR-3x8nxn; URL: www.ensaiosclinicos.gov.br.

Handgrip Force and Maximum Inspiratory and Expiratory Pressures in Critically Ill Patients With a Tracheostomy

BACKGROUND

The association between peripheral striated muscle strength and respiratory muscle strength has been confirmed in a number of disorders. However, this association is unknown in intensive care unit patients with tracheostomies.

OBJECTIVE

To examine correlations between handgrip force, maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP) in intensive care unit patients with tracheostomies.

METHODS

Twenty patients (7 women, 13 men) with tracheostomies, in the intensive care unit longer than 11 days, in stable condition, with functional limbs, and with Glasgow Coma Scale scores of 15 were recruited. Both MIP and MEP were measured with a membrane manometer; handgrip force was measured with a hydraulic hand dynamometer.

RESULTS

Handgrip force was significantly correlated with MIP (r = 0.45, P = .04) and MEP (r = 0.78, P = .001). Handgrip force was significantly predicted by MIP and MEP when the effect of sex was controlled for (P < .05). However, when MIP and MEP were included as predictors in a regression model, MEP was the only significant predictor (R = 0.80, R2 = 0.63, adjusted R2 = 0.57).

CONCLUSIONS

Strength of the hand flexors and strength of the expiratory muscles (abdominal) were significantly correlated in intensive care unit patients. Handgrip strength appears to be an easy, fast way to evaluate expiratory muscle strength by using a simple handhold command without special equipment. A strong handhold may also correspond to strong expiratory muscles. ClinicalTrials.gov: NCT03457376.

Global Physiology and Pathophysiology of Cough: Part 1: Cough Phenomenology - CHEST Guideline and Expert Panel Report

The purpose of this state-of-the-art review is to update the American College of Chest Physicians 2006 guideline on global physiology and pathophysiology of cough. A review of the literature was conducted using PubMed and MEDLINE databases from 1951 to 2019 and using prespecified search terms. We describe the basic phenomenology of cough patterns, behaviors, and morphological features. We update the understanding of mechanical and physiological characteristics of cough, adding a contemporary view of the types of cough and their associated behaviors and sensations. New information about acoustic characteristics is presented, and recent insights into cough triggers and the patient cough hypersensitivity phenotype are explored. Lastly, because the clinical assessment of patients largely focuses on the duration rather than morphological features of cough, we review the morphological features of cough that can be measured in the clinic. This is the first of a two-part update to the American College of Chest Physicians 2006 cough guideline; it provides a more global consideration of cough phenomenology, beyond simply the mechanical aspects of a cough. A greater understanding of the typical features of cough, and their variations, may allow a more informed interpretation of cough measurements and the clinical relevance for patients.

Prolonged Weaning: S2k Guideline Published by the German Respiratory Society

Mechanical ventilation (MV) is an essential part of modern intensive care medicine. MV is performed in patients with severe respiratory failure caused by respiratory muscle insufficiency and/or lung parenchymal disease; that is, when other treatments such as medication, oxygen administration, secretion management, continuous positive airway pressure (CPAP), or nasal high-flow therapy have failed. MV is required for maintaining gas exchange and allows more time to curatively treat the underlying cause of respiratory failure. In the majority of ventilated patients, liberation or "weaning" from MV is routine, without the occurrence of any major problems. However, approximately 20% of patients require ongoing MV, despite amelioration of the conditions that precipitated the need for it in the first place. Approximately 40-50% of the time spent on MV is required to liberate the patient from the ventilator, a process called "weaning". In addition to acute respiratory failure, numerous factors can influence the duration and success rate of the weaning process; these include age, comorbidities, and conditions and complications acquired during the ICU stay. According to international consensus, "prolonged weaning" is defined as the weaning process in patients who have failed at least 3 weaning attempts, or require more than 7 days of weaning after the first spontaneous breathing trial (SBT). Given that prolonged weaning is a complex process, an interdisciplinary approach is essential for it to be successful. In specialised weaning centres, approximately 50% of patients with initial weaning failure can be liberated from MV after prolonged weaning. However, the heterogeneity of patients undergoing prolonged weaning precludes the direct comparison of individual centres. Patients with persistent weaning failure either die during the weaning process, or are discharged back to their home or to a long-term care facility with ongoing MV. Urged by the growing importance of prolonged weaning, this Sk2 Guideline was first published in 2014 as an initiative of the German Respiratory Society (DGP), in conjunction with other scientific societies involved in prolonged weaning. The emergence of new research, clinical study findings and registry data, as well as the accumulation of experience in daily practice, have made the revision of this guideline necessary. The following topics are dealt with in the present guideline: Definitions, epidemiology, weaning categories, underlying pathophysiology, prevention of prolonged weaning, treatment strategies in prolonged weaning, the weaning unit, discharge from hospital on MV, and recommendations for end-of-life decisions. Special emphasis was placed on the following themes: (1) A new classification of patient sub-groups in prolonged weaning. (2) Important aspects of pulmonary rehabilitation and neurorehabilitation in prolonged weaning. (3) Infrastructure and process organisation in the care of patients in prolonged weaning based on a continuous treatment concept. (4) Changes in therapeutic goals and communication with relatives. Aspects of paediatric weaning are addressed separately within individual chapters. The main aim of the revised guideline was to summarize both current evidence and expert-based knowledge on the topic of "prolonged weaning", and to use this information as a foundation for formulating recommendations related to "prolonged weaning", not only in acute medicine but also in the field of chronic intensive care medicine. The following professionals served as important addressees for this guideline: intensivists, pulmonary medicine specialists, anaesthesiologists, internists, cardiologists, surgeons, neurologists, paediatricians, geriatricians, palliative care clinicians, rehabilitation physicians, intensive/chronic care nurses, physiotherapists, respiratory therapists, speech therapists, medical service of health insurance, and associated ventilator manufacturers.

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.

Early predictors of in-hospital mortality in patients with COVID-19 in a large American cohort

Coronavirus disease (COVID-19) has aggressively spread across the United States with numerous fatalities. Risk factors for mortality are poorly described. This was a multicentered cohort study identifying patient characteristics and diagnostic markers present on initial evaluation associated with mortality in hospitalized COVID-19 patients. Epidemiological, demographic, clinical, and laboratory characteristics of survivors and non-survivors were obtained from electronic medical records and a multivariable survival regression analysis was conducted to identify risk factors of in-hospital death. Of 1629 consecutive hospitalized adult patients with confirmed COVID-19 from March 1st thru March 31, 2020, 1461 patients were included in final analysis. 327 patients died during hospitalization and 1134 survived to discharge. Median age was 62 years (IQR 50.0, 74.0) with 56% of hospitalized patients under the age of 65. 47% were female and 63% identified as African American. Most patients (55%) had either no or one comorbidity. In multivariable analysis, older age, admission respiratory status including elevated respiratory rate and oxygen saturation ≤ 88%, and initial laboratory derangements of creatinine > 1.33 mg/dL, alanine aminotransferase > 40 U/L, procalcitonin > 0.5 ng/mL, and lactic acid ≥ 2 mmol/L increased risk of in-hospital death. This study is one of the largest analyses in an epicenter for the COVID-19 pandemic. Older age, low oxygen saturation and elevated respiratory rate on admission, and initial lab derangements including renal and hepatic dysfunction and elevated procalcitonin and lactic acid are risk factors for in-hospital death. These factors can help clinicians prognosticate and should be considered in management strategies.

Comparison of "cough peak expiratory flow measurement" and "cough strength measurement using the white card test" in extubation success: A randomized controlled trial

Background:

Failed extubation and subsequent re-intubation in ventilated patients can lead to many adverse consequences, including organizational and personal expenditures. Extubation decisions based on subjective methods are a major contributor to extubation failure. This study compared the effect of cough peak expiratory flow (PEF) measurement and cough strength measurement using the white card test (WCT) on extubation success.

Materials and Methods:

This randomized clinical trial was conducted in two groups in 2018 on 88 ventilated patients in intensive care units of Imam Reza Hospital in Mashhad, Iran. Ninety patients were divided into two groups of 45, but two were excluded from the white card group. The criteria established for extubation included PEF ≥60 L/min during coughing in the cough PEF group and noticing card humidity in the WCT group. In both groups, extubation success was determined as the sole outcome and was compared with the standard PEF and cough strength. The researcher who assessed the outcome and statistician were blinded about group allocation.

Results:

Extubation success was measured as 97.8% in the cough PEF group and 76.7% in the WCT group (P = 0.003) during the first 24 h. In the second 24 h, however, successful extubation was reported as 90.9% in the cough PEF group and 60.6% in the WCT group (P = 0.002).

Conclusion:

Using the cough PEF rate increases the likelihood of extubation success and reduces adverse effects, and is recommended to be used for extubation decision-making.

Role of ICU-acquired weakness on extubation outcome among patients at high risk of reintubation

Background

Whereas ICU-acquired weakness may delay extubation in mechanically ventilated patients, its influence on extubation failure is poorly known. This study aimed at assessing the role of ICU-acquired weakness on extubation failure and the relation between limb weakness and cough strength.

Methods

A secondary analysis of two previous prospective studies including patients at high risk of reintubation after a planned extubation, i.e., age greater than 65 years, with underlying cardiac or respiratory disease, or intubated for more than 7 days prior to extubation. Patients intubated less than 24 h and those with a do-not-reintubate order were not included. Limb and cough strength were assessed by a physiotherapist just before extubation. ICU-acquired weakness was clinically diagnosed as limb weakness defined as Medical Research Council (MRC) score < 48 points and severe weakness as MRC sum-score < 36. Cough strength was assessed using a semi-quantitative 5-Likert scale. Extubation failure was defined as reintubation or death within the first 7 days following extubation.

Results

Among 344 patients at high risk of reintubation, 16% experienced extubation failure (56/344). They had greater severity and lower MRC sum-score (41 ± 16 vs. 49 ± 13, p < 0.001) and were more likely to have ineffective cough than the others. The prevalence of ICU-acquired weakness at the time of extubation was 38% (130/244). The extubation failure rate was 12% (25/214) in patients with no limb weakness vs. 18% (12/65) and 29% (19/65) in those with moderate and severe limb weakness, respectively (p < 0.01). MRC sum-score and cough strength were weakly but significantly correlated (rho = 0.28, p < .001). After multivariate logistic regression analyses, the lower the MRC sum-score the greater the risk of reintubation; severe limb weakness was independently associated with extubation failure, even after adjustment on cough strength and severity at admission.

Conclusion

ICU-acquired weakness was diagnosed in 38% in this population of patients at high risk at the time of extubation and was independently associated with extubation failure in the ICU.

Outcome of Prophylactic Noninvasive Ventilation Following Planned Extubation in High-risk Patients: A Two-year Prospective Observational Study from a General Intensive Care Unit

Introduction

Prophylactic use of noninvasive ventilation (NIV) is recommended following extubation in patients at high risk of extubation failure. In a prospective cohort study, we examined the impact of prophylactic NIV in this subset of patients, potentially exploring the risk factors for extubation failure in them and the impact of extubation failure on organ function. We also explored the effect of fluid balance on extubation failure or success in this high-risk patient subgroup.

Materials and methods

Consecutive adult patients (≥18 years) admitted in the mixed intensive care unit (ICU) of a tertiary care center, between January 1, 2018, and December 31, 2019, who passed a spontaneous breathing trial (SBT) following at least 12 hours of invasive mechanical ventilation and put on prophylactic NIV for being at a high risk of extubation failure, were prospectively followed throughout their hospital stay. Extubation failure was defined as developing respiratory failure within 72 hours postextubation requiring reintubation or still requiring NIV support at 72 hours postextubation.

Results

A total of 85 patients were included in the study. 11.8% of patients had extubation failure at 72 hours with an overall reintubation rate of 10.5%. Higher age (p < 0.05), longer duration of invasive ventilation (p < 0.05), and higher sequential organ failure assessment (SOFA) score at extubation (p < 0.05) were identified as risk factors for extubation failure in univariate analysis. However, in the multivariate analysis, only a higher SOFA score remained statistically significant in forward logistic regression analysis (p < 0.05). We found a clear trend toward worsening organ function score in the extubation failure group in the first 72 hours postextubation, suggesting extubation failure as a risk factor for organ dysfunction. Cumulative fluid balance was higher both at extubation and in subsequent 3 days postextubation in the failure group, but the differences were not statistically significant.

Conclusion

Higher age, longer duration of invasive ventilation, and higher baseline SOFA score at extubation remain risk factors for extubation failure even in this high-risk subset of patients on prophylactic NIV. Extubation failure is associated with the worsening of organ function. A trend toward higher cumulative fluid balance both at extubation and postextubation, suggests aggressive de-resuscitation as a potentially helpful strategy in preventing extubation failure.

How to cite this article

Ghosh S, Chawla A, Jhalani R, Salhotra R, Arora G, Nagar S, et al. Outcome of Prophylactic Noninvasive Ventilation Following Planned Extubation in High-risk Patients: A Two-year Prospective Observational Study from a General Intensive Care Unit. Indian J Crit Care Med 2020;24(12):1185–1192.

Endotracheal tube cuff pressure change: Proof of concept for a novel approach to objective cough assessment in intubated critically ill patients

PURPOSE

Cough strength assessment aids in predicting extubation failure. Peak expiratory flow rate during cough manoeuvre (CPF) is the gold-standard tool and flow rates of <60l/min suggest risk of failed extubation. We aimed to assess endotracheal tube cuff pressure change (ΔP_cuff) as a novel method of objective cough strength assessment in intubated patients considered for extubation.

MATERIALS AND METHODS

Paired measurements of CPF and ΔP_cuff were sampled during cough manoeuvres by intubated recovering critically ill patients. Spearman's correlation was used to assess agreement between the variables. Categorical data and receiver operating characteristic (ROC) curve analysis were undertaken to assess discriminating ability of ΔP_cuff to identify low CPF.

RESULTS

In total, 42 patients yielded 81 paired measurements. Paired samples with the highest CPF per patient had a correlation coefficient of 0.74. The composite of all samples had a correlation coefficient of 0.77. Regression analysis showed CPF=60l/min equates to ΔP_cuff=28cmH₂O with categorical analysis using these cut-offs showing significant dependence between the variables (p = 0.000001). ROC curve analysis identified an area under the curve (AUC) of 0.9 [95% CI (0.84, 0.97)], with optimal sensitivity and specificity of ΔP_cuff at 20cmH₂O.

CONCLUSIONS

We identified a good correlation between CPF and ΔP_cuff. Our research showed that overall discriminating ability of ΔP_cuff in identifying CPF <60l/min was excellent. Further studies, looking at ΔP_cuff and extubation outcomes are required to establish clinical utility.

Ventilatory support after extubation in critically ill patients

The periextubation period represents a crucial moment in the management of critically ill patients. Extubation failure, defined as the need for reintubation within 2-7 days after a planned extubation, is associated with prolonged mechanical ventilation, increased incidence of ventilator-associated pneumonia, longer intensive care unit and hospital stays, and increased mortality. Conventional oxygen therapy is commonly used after extubation. Additional methods of non-invasive respiratory support, such as non-invasive ventilation and high-flow nasal therapy, can be used to avoid reintubation. The aim of this Review is to describe the pathophysiological mechanisms of postextubation respiratory failure and the available techniques and strategies of respiratory support to avoid reintubation. We summarise and discuss the available evidence supporting the use of these strategies to achieve a tailored therapy for an individual patient at the bedside.

[Research advances in validity of predictors for extubation outcome in children receiving invasive mechanical ventilation]

The development of invasive mechanical ventilation technology provides effective respiratory support for critically ill children. However, respiratory support is not the end of treatment as the ultimate goal is successful extubation in children. At present, some evaluation indicators before extubation including rapid shallow breathing index, maximal inspiratory pressure, and work of breathing are of high clinical value in predicting adult extubation outcome, but their evidence of evidence-based medicine is not sufficient in the field of pediatric intensive care. This paper reviews the current research on the validity of predictors for extubation outcomes in children. It shows that there is still a lack of indicators with good sensitivity and specificity for assessment before extubation in children. The studies are still in a small-sample size and single-center stage. Therefore, how to optimize evaluation before extubation and improve the success rate of extubation is the direction of joint efforts of doctors in the pediatric intensive care unit and rehabilitation medicine department.

Inability of Diaphragm Ultrasound to Predict Extubation Failure: A Multicenter Study

BACKGROUND

Diaphragmatic dysfunction may promote weaning difficulties in patients who are mechanically ventilated.

OBJECTIVE

The goal of this study was to assess whether diaphragm dysfunction detected by ultrasound prior to extubation could predict extubation failure in the ICU.

METHODS

This multicenter prospective study included patients at high risk of reintubation: those aged > 65 years, with underlying cardiac or respiratory disease, or intubated > 7 days. All patients had successfully undergone a spontaneous breathing trial. Diaphragmatic function was assessed by ultrasound prior to extubation while breathing spontaneously on a T-piece. Bilateral diaphragmatic excursion and apposition thickening fraction were measured, and diaphragmatic dysfunction was defined as excursion < 10 mm or thickening < 30%. Cough strength was clinically assessed by physiotherapists. Extubation failure was defined as reintubation or death within the 7 days following extubation.

RESULTS

Over a 20-month period, 191 at-risk patients were studied. Among them, 33 (17%) were considered extubation failures. The proportion of patients with diaphragmatic dysfunction was similar between those whose extubation succeeded and those whose extubation failed: 46% vs 51% using excursion (P = .55), and 71% vs 68% using thickening (P = .73), respectively. Values of excursion and thickening did not differ between the success and the failure groups: at right, excursion was 14 ± 7 mm vs 11 ± 8 (P = .13), and thickening was 29 ± 29% vs 38 ± 48% (P = .83), respectively. Extubation failure rates were 7%, 22%, and 46% in patients with effective, moderate, and ineffective cough (P < .01). Ineffective cough was the only variable independently associated with extubation failure.

CONCLUSIONS

Diaphragmatic dysfunction assessed by ultrasound was not associated with an increased risk of extubation failure.