Lung-thorax compliance measured during a spontaneous breathing trial is a good index of extubation failure in the surgical intensive care unit: a retrospective cohort study

Rapid shallow breathing index predicting extubation outcomes: A systematic review and meta-analysis

OBJECTIVE

This meta-analysis aimed to assess the predictive value of the rapid shallow breathing index for extubation outcomes.

METHODOLOGY

We conducted a systematic review of literature (inception to March 2023) and a meta-analysis. Statistical analysis was performed using Meta-Disc 1.4 software, RevMan 5.4 software and Stata 14.0 software to evaluate the predictive value of RSBI for extubation outcomes.

RESULTS

A total of 1,987 studies were retrieved, and after applying the inclusion criteria, 79 studies were included in the final analysis, involving 13,170 patients undergoing mechanical ventilation. The random-effects model was employed for statistical analysis. The summary receiver operating characteristic curves (SROC) area under the curve (AUC) was 0.8144. The pooled sensitivity was 0.60 (95% CI: 0.59, 0.61), the pooled specificity was 0.68 (95% CI: 0.66, 0.70).

CONCLUSIONS

The Rapid Shallow Breathing Index demonstrated moderate accuracy, poor pooled sensitivity and specificity in predicting successful extubation, however the study does not present adequate data to support or reject the use of this tool as a single parameter that predicts extubation outcome. Future studies should explore the combination of The Rapid Shallow Breathing Index with other indicators and clinical experience to improve the success rate of extubation and reduce the risk of extubation failure.

IMPLICATIONS FOR CLINICAL PRACTICE

Premature and delayed extubation in mechanically ventilated patients can have a negative impact on prognosis and prolong hospital stay. The Rapid Shallow Breathing Index is a simple, cost-effective, and easily monitored objective evaluation index, which can be used to predict the outcome of extubation, especially in primary hospitals. Our study comprehensively evaluated the value of this tool in predicting extubation outcomes, which can help clinicians combine subjective experience with objective indicators to improve the accuracy of extubation time decisions.

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.

Ventilatory ratio and mechanical power in prolonged mechanically ventilated COVID-19 patients versus respiratory failures of other etiologies

BACKGROUND

Evidence suggests differences in ventilation efficiency and respiratory mechanics between early COVID-19 pneumonia and classical acute respiratory distress syndrome (ARDS), as measured by established ventilatory indexes, such as the ventilatory ratio (VR; a surrogate of the pulmonary dead-space fraction) or mechanical power (MP; affected, e.g., by changes in lung-thorax compliance).

OBJECTIVES

The aim of this study was to evaluate VR and MP in the late stages of the disease when patients are ready to be liberated from the ventilator after recovering from COVID-19 pneumonia compared to respiratory failures of other etiologies.

DESIGN

A retrospective observational cohort study of 249 prolonged mechanically ventilated, tracheotomized patients with and without COVID-19-related respiratory failure.

METHODS

We analyzed each group's VR and MP distributions and trajectories [repeated-measures analysis of variance (ANOVA)] during weaning. Secondary outcomes included weaning failure rates between groups and the ability of VR and MP to predict weaning outcomes (using logistic regression models).

RESULTS

The analysis compared 53 COVID-19 cases with a heterogeneous group of 196 non-COVID-19 subjects. VR and MP decreased across both groups during weaning. COVID-19 patients demonstrated higher values for both indexes throughout weaning: median VR 1.54 versus 1.27 (p < 0.01) and MP 26.0 versus 21.3 Joule/min (p < 0.01) at the start of weaning, and median VR 1.38 versus 1.24 (p < 0.01) and MP 24.2 versus 20.1 Joule/min (p < 0.01) at weaning completion. According to the multivariable analysis, VR was not independently associated with weaning outcomes, and the ability of MP to predict weaning failure or success varied with lung-thorax compliance, with COVID-19 patients demonstrating consistently higher dynamic compliance along with significantly fewer weaning failures (9% versus 30%, p < 0.01).

CONCLUSION

COVID-19 patients differed considerably in ventilation efficiency and respiratory mechanics among prolonged ventilated individuals, demonstrating significantly higher VRs and MP. The differences in MP were linked with higher lung-thorax compliance in COVID-19 patients, possibly contributing to the lower rate of weaning failures observed.

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.

Mechanical power normalized to lung-thorax compliance indicates weaning readiness in prolonged ventilated patients

Since critical respiratory muscle workload is a significant determinant of weaning failure, applied mechanical power (MP) during artificial ventilation may serve for readiness testing before proceeding on a spontaneous breathing trial (SBT). Secondary analysis of a prospective, observational study in 130 prolonged ventilated, tracheotomized patients. Calculated MP’s predictive SBT outcome performance was determined using the area under receiver operating characteristic curve (AUROC), measures derived from k-fold cross-validation (likelihood ratios, Matthew's correlation coefficient [MCC]), and a multivariable binary logistic regression model. Thirty (23.1%) patients failed the SBT, with absolute MP presenting poor discriminatory ability (MCC 0.26; AUROC 0.68, 95%CI [0.59‒0.75], p = 0.002), considerably improved when normalized to lung-thorax compliance (LTC_dyn-MP, MCC 0.37; AUROC 0.76, 95%CI [0.68‒0.83], p < 0.001) and mechanical ventilation P_aCO₂ (so-called power index of the respiratory system [PI_rs]: MCC 0.42; AUROC 0.81 [0.73‒0.87], p < 0.001). In the logistic regression analysis, PI_rs (OR 1.48 per 1000 cmH₂O²/min, 95%CI [1.24‒1.76], p < 0.001) and its components LTC_dyn-MP (1.25 per 1000 cmH₂O²/min, [1.06‒1.46], p < 0.001) and mechanical ventilation P_aCO₂ (1.17 [1.06‒1.28], p < 0.001) were independently related to SBT failure. MP normalized to respiratory system compliance may help identify prolonged mechanically ventilated patients ready for spontaneous breathing.

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/.

Electrical Impedance Tomography Predicts Weaning Success in Adult Patients With Delayed Upper Abdominal Surgery: A Single-Center Retrospective Study

Objective: To evaluate the predictive value of electrical impedance tomography (EIT) in patients with delayed ventilator withdrawal after upper abdominal surgery.

Methods: We retrospectively analyzed data of patients who were ventilated >24 h after upper abdominal surgery between January 2018 and August 2019. The patients were divided into successful (group S) and failed (group F) weaning groups. EIT recordings were obtained at 0, 5, 15, and 30 min of spontaneous breathing trials (SBTs) with SBT at 0 min set as baseline. We assessed the change in delta end-expiratory lung impedance and tidal volume ratio (ΔEELI/VT) from baseline, the change in compliance change percentage variation (|Δ(CW-CL)|) from baseline, the standard deviation of regional ventilation delay index (RVDSD), and global inhomogeneity (GI) using generalized estimation equation analyses. Receiver operating characteristic curve analyses were performed to evaluate the predictive value of parameters indicating weaning success.

Results: Among the 32 included patients, ventilation weaning was successful in 23 patients but failed in nine. Generalized estimation equation analysis showed that compared with group F, the ΔEELI/VT was lower, and the GI, RVDSD, and (|Δ(CW-CL)|) were higher in group S. For predicting withdrawal failure, the areas under the curve of the ΔEELI/VT, (|Δ(CW-CL)|), and the RVDSD were 0.819, 0.918, and 0.918, and 0.816, 0.884, and 0.918 at 15 and 30 min during the SBTs, respectively.

Conclusion: The electrical impedance tomography may predict the success rate of ventilator weaning in patients with delayed ventilator withdrawal after upper abdominal surgery.

Investigating the Effect of Expiratory Time Constant on Outcome in Intubated Patients with Acute Respiratory Failure Caused by COVID-19 in Critical Care Unit: A Research Study

Background

The coronavirus disease 2019 (COVID-19) has a high prevalence and mortality worldwide. Thousands of patients with acute respiratory failure caused by COVID-19 are daily hospitalized in intensive care units (ICUs) around the world. Many of these patients require full mechanical respiratory support and long-term ventilator use. Using different ventilators and calculating important variables can be helpful in meeting therapeutic needs of patients.

Objectives

The aim of present study was to investigate the effect of expiratory time constant (RCEXP) on the course of treatment and duration of mechanical ventilation in patients with acute respiratory failure hospitalized in ICU.

Methods

The present cross-sectional study was conducted on 60 patients with acute respiratory failure who were hospitalized in the ICU and underwent mechanical ventilation due to COVID-19 in the first six months of 2020. The variables of RCEXP, lung compliance and lung resistance in all patients were recorded daily and analyzed. Then, based on clinical outcome, the patients were divided into two groups: the patients with wean outcome (N = 40) and those with death outcome (N = 20).

Results

The mean ± SD of lung compliance in patients who were separated from ventilator and patients with death outcome were 74.73 (18.58) mL/cm H₂O and 36.92 (10.56) mL/cm H₂O, respectively, which was statistically significant (P = 0.001). The mean ± SD of lung resistance in patients who were separated from ventilator and patients with death outcome were calculated at 9.25 (4.62) and 14 (6.5), respectively, which was statistically significant (P = 0.015). Also, there was a statistically significant difference between the two groups in terms of mean ± SD of RCEXP (0.67 (0.23) vs. 0.49 (0.19), P = 0.010).

Conclusions

According to the results of this study, there was a significant difference between high resistance, low compliance, RCEXP, and weaning success of intubation in patients hospitalized in the ICU.

Prediction of extubation outcome in critically ill patients: a systematic review and meta-analysis

BACKGROUND

Extubation failure is an important issue in ventilated patients and its risk factors remain a matter of research. We conducted a systematic review and meta-analysis to explore factors associated with extubation failure in ventilated patients who passed a spontaneous breathing trial and underwent planned extubation. This systematic review was registered in PROPERO with the Registration ID CRD42019137003.

METHODS

We searched the PubMed, Web of Science and Cochrane Controlled Register of Trials for studies published from January 1998 to December 2018. We included observational studies involving risk factors associated with extubation failure in adult intensive care unit patients who underwent invasive mechanical ventilation. Two authors independently extracted data and assessed the validity of included studies.

RESULTS

Sixty-seven studies (involving 26,847 participants) met the inclusion criteria and were included in our meta-analysis. We analyzed 49 variables and, among them, we identified 26 factors significantly associated with extubation failure. Risk factors were distributed into three domains (comorbidities, acute disease severity and characteristics at time of extubation) involving mainly three functions (circulatory, respiratory and neurological). Among these, the physiological respiratory characteristics at time of extubation were the most represented. The individual topic of secretion management was the one with the largest number of variables. By Bayesian multivariable meta-analysis, twelve factors were significantly associated with extubation failure: age, history of cardiac disease, history of respiratory disease, Simplified Acute Physiologic Score II score, pneumonia, duration of mechanical ventilation, heart rate, Rapid Shallow Breathing Index, negative inspiratory force, lower PaO2/FiO2 ratio, lower hemoglobin level and lower Glasgow Coma Scale before extubation, with the latest factor having the strongest association with extubation outcome.

CONCLUSIONS

Numerous factors are associated with extubation failure in critically ill patients who have passed a spontaneous breathing trial. Robust multiparametric clinical scores and/or artificial intelligence algorithms should be tested based on the selected independent variables in order to improve the prediction of extubation outcome in the clinical scenario.

Mechanical power normalized to lung-thorax compliance predicts prolonged ventilation weaning failure: a prospective study

Background

Mechanical power (MP) of artificial ventilation, the energy transferred to the respiratory system, is a chief determinant of adequate oxygenation and decarboxylation. Calculated MP, the product of applied airway pressure and minute ventilation, may serve as an estimate of respiratory muscle workload when switching to spontaneous breathing. The aim of the study was to assess MP’s discriminatory performance in predicting successful weaning from prolonged tracheostomy ventilation.

Methods

Prospective, observational study in 130 prolonged mechanically ventilated, tracheotomized patients in a specialized weaning center. Predictive weaning outcome ability of arterial blood gas analyses and indices derived from calculated MP at beginning and end of weaning was determined in terms of area under receiver operating characteristic curve (AUROC) and measures derived from k-fold cross-validation (likelihood ratios, diagnostic odds ratio, F₁ score, and Matthews correlation coefficient [MCC]).

Results

Forty-four (33.8%) patients experienced weaning failure. Absolute MP showed poor discrimination in predicting outcome; whereas specific MP (MP normalized to dynamic lung-thorax compliance, LTC_dyn-MP) had moderate diagnostic accuracy (MCC 0.38; AUROC 0.79, 95%CI [0.71‒0.86], p < 0.001), further improved by correction for corresponding mechanical ventilation P_aCO₂ (termed the power index of the respiratory system [PI_rs]: MCC 0.52; AUROC 0.86 [0.79‒0.92], p < 0.001). Diagnostic performance of MP indices increased over the course of weaning, with maximum accuracy immediately before completion (LTC_dyn-MP: MCC 0.49; AUROC 0.86 [0.78‒0.91], p < 0.001; PI_rs: MCC 0.68; AUROC 0.92 [0.86‒0.96], p < 0.001).

Conclusions

MP normalized to dynamic lung-thorax compliance, a surrogate for applied power per unit of ventilated lung volume, accurately discriminated between low and high risk for weaning failure following prolonged mechanical ventilation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01566-8.

Variables predicting weaning outcome in prolonged mechanically ventilated tracheotomized patients: a retrospective study

Background

Several studies have assessed predictors of weaning and extubation outcome in short-term mechanically ventilated patients, but there are only few studies on predictors of weaning from prolonged mechanical ventilation.

Methods

Retrospective, single-center, observational study at a specialized national weaning center in Germany. Patients’ medical records were reviewed to obtain data on demographics, comorbidities, respiratory indices, and the result of a prospectively documented, standardized spontaneous breathing trial (SBT) upon admission to the weaning center. Respiratory indices assessed were the ventilatory ratio (VR) and parameters derived from calculated mechanical power (MP). Predictors associated with failure of prolonged weaning and failure of the SBT were assessed using a binary logistic regression model.

Results

A total of 263 prolonged mechanically ventilated, tracheotomized patients, treated over a 5-year period were analyzed. After 3 weeks of mechanical ventilation, patients with unsuccessful weaning failed a SBT more frequently and showed significantly increased values for inspiratory positive airway pressure, driving pressure, VR, absolute MP, and MP normalized to predicted body weight and dynamic lung-thorax compliance (LTC-MP). In the logistic regression analyses, variables independently correlated with weaning failure were female gender (adjusted odds ratio 0.532 [95% CI 0.291–0.973]; p = 0.040), obesity (body mass index ≥ 30 kg/m²) (2.595 [1.210–5.562]; p = 0.014), COPD (3.209 [1.563–6.589]; p = 0.002), LTC-MP (3.470 [1.067–11.284]; p = 0.039), P_aCO₂ on mechanical ventilation (1.101 [95% CI 1.034–1.173]; p = 0.003), and failure of the SBT (4.702 [2.250–9.825]; p < 0.001). In addition, female gender (0.401 [0.216–0.745]; p = 0.004), LTC-MP (3.017 [1.027–8.862]; p = 0.046), and P_aCO₂ on mechanical ventilation (1.157 [1.083–1.235]; p < 0.001) were independent risk factors for an unsuccessful SBT.

Conclusions

In the present study, the derived predictors of weaning point to a crucial role of the workload imposed on respiratory muscles during spontaneous breathing. Mechanical power normalized to lung-thorax compliance was independently correlated with weaning outcome and may identify patients at high risk for weaning failure.