Maximum inspiratory pressure and rapid shallow breathing index as predictors of successful ventilator weaning

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.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Chinese Clinical Trial Registry website (ChiCTR2200065422).

Respiratory Monitoring During Mechanical Ventilation: The Present and the Future

The increased application of mechanical ventilation, the recognition of its harms and the interest in individualization raised the need for an effective monitoring. An increasing number of monitoring tools and modalities were introduced over the past 2 decades with growing insight into asynchrony, lung and chest wall mechanics, respiratory effort and drive. They should be used in a complementary rather than a standalone way. A sound strategy can guide a reduction in adverse effects like ventilator-induced lung injury, ventilator-induced diaphragm dysfunction, patient-ventilator asynchrony and helps early weaning from the ventilator. However, the diversity, complexity, lack of expertise, and associated cost make formulating the appropriate monitoring strategy a challenge for clinicians. Most often, a big amount of data is fed to the clinicians making interpretation difficult. Therefore, it is fundamental for intensivists to be aware of the principle, advantages, and limits of each tool. This analytic review includes a simplified narrative of the commonly used basic and advanced respiratory monitors along with their limits and future prospective.

Inspiratory Muscle Training Strategies in Tracheostomized Critically Ill Individuals

BACKGROUND

Inspiratory muscle training (IMT) strategies can reduce ICU length of stay and optimize recovery in critically ill patients. Our objective was to compare IMT combined with spontaneous breathing with T-piece in tracheostomized subjects.

METHODS

Tracheostomized critically ill subjects who were ready to wean were selected and randomly allocated to one of 2 groups: electronically-assisted IMT (EIMT) or spontaneous breathing with T-piece. Electronically assisted IMT was delivered using 30% of maximal inspiratory pressure (manual EIMT or automatically adjusted loads). The following variables were analyzed: ICU length of stay, weaning time, maximal inspiratory pressure, rapid shallow breathing index, pressure (cm H₂O), power (W), flow (L/s), volume (L), and energy (J).

RESULTS

A total of 132 patients were assessed; 104 subjects were enrolled with EIMT, n = 51 (automatic EIMT, n = 25 and manual EIMT n = 26), or spontaneous breathing with T-piece group, n = 53. The Acute Physiology and Chronic Health Evaluation II score was significantly higher (P = .02) in subjects in the manual EIMT group. Weaning time did not differ significantly between groups (8.55 ± 6.48 d and 10.86 ± 6.48 d, EIMT and spontaneous breathing with T-piece group, respectively; P = .23). Weaning success rates (75%) were lower in the manual EIMT group. Invasive mechanical ventilation time was longer but not significantly different (P = .21) in the spontaneous breathing with T-piece group. Maximal inspiratory pressure was significantly higher in the spontaneous breathing with T-piece and the automatic EIMT groups (P < .001 and P = .007, respectively). Pressure, power, and energy values were significantly higher in the manual EIMT group (P < .001, P = .003, and P = .003, respectively).

CONCLUSIONS

IMT modalities in this trial had no significant impacts on weaning time or successful weaning rates.

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.

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/.

Is the asynchronous phase of thoracoabdominal movement a novel feature of successful extubation? A preliminary result

Mechanical ventilation is necessary to maintain patients' life in intensive care units. However, too early or too late extubation may injure the muscles or lead to respiratory failure. Therefore, the spontaneous breathing trial (SBT) is applied for testing whether the patients can spontaneously breathe or not. However, previous evidence still reported 15%~20% of the rate of extubation fail. The monitor only considers the ventilation variables during SBT. Therefore, this study measures the asynchronization between thoracic and abdomen wall movement (TWM and AWM) by using instantaneous phase difference method (IPD) during SBT for 120 minutes. The respiratory inductive plethysmography were used for TWM and AWM measurement. The preliminary result recruited 31 signals for further analysis. The result showed that in successful extubation group can be classified into two groups, IPD increase group, and IPD decrease group; but in extubation fail group, the IPD value only increase. Therefore, the IPD decrease group can almost perfectly be discriminated with extubation fail group, especially after 70 minutes (Area under curve of operating characteristic curve was 1). These results showed IPD is an important key factor to find whether the patient is suitable for extubation or not. These finding suggest that the asynchronization between TWM and AWM should be considered as a predictor of extubation outcome. In future work, we plan to recruit 150 subjects to validate the result of this preliminary result. In addition, advanced machine learning method is considered to apply for building effective models to discriminate the IPD increase group and extubation fail group.Clinical Relevance- The finding of this study is that the patients whose average IPD of 95 to 100 minutes was smaller than average IPD of first 5 minutes of SBT could be 100% successful extubation. In addition, ability of discrimination of average IPD after 70 minutes presents AUC 1.

Does diaphragm ultrasound improve the rapid shallow breathing index accuracy for predicting the success of weaning from mechanical ventilation?

BACKGROUND

This prospective study investigated whether taking into account diaphragmatic excursion (DE) measured by ultrasonography would improve the performance of the rapid shallow breathing index (RSBI) to predict extubation success or failure.

OBJECTIVES

The aim of the study was to compare the new composite index named the rapid shallow diaphragmatic index (RSDI), and the RSBI measured during a spontaneous breathing trial regarding their ability to predict the need for re-intubation at 72 h.

METHODS

One hundred mechanically ventilated patients underwent daily 30-min spontaneous breathing trials (SBTs) under pressure support ventilation of 6 cm H₂O and end-expiratory pressure of 0 cm H₂O until the SBT was considered successful and followed by extubation. The performances of RSBI (respiratory rate/tidal volume) and of the ratio RSBI/DE measured at 5 and 25 min of the successful SBT were compared in terms of area under the receiver operating characteristics curve (AUC), for predicting extubation success at 72 h. As secondary analysis, extubation and weaning success at 7 d were also considered. As exploratory analyses, predictive indices incorporating both clinical characteristics, the DE, and ultrasound diaphragm thickening fraction (DTF) were investigated.

RESULTS

RSBI and RSBI/DE showed AUCs with 95% confidence intervals consistently extending below 0.50, either at the 5th (0.55 [0.36-0.74] and 0.55 [0.34-0.75], respectively) or at the 25th minute of SBT (0.49 [0.27-0.71] and 0.50 [0.29-0.68], respectively) for predicting weaning success at 72 h or at 7 d (5th min: 0.53 [0.37-0.70] and 0.54 [0.37-0.70], respectively; 25th min: 0.54 [0.37-0.71] and 0.55 [0.39-0.71], respectively). An exploratory index incorporating the accessory respiratory muscle activity, DE, DTF, and respiratory rate at 5th min of SBT showed AUCs for predicting extubation success at 7 d in the 78 patients with DTF measurement (0.77 [0.64-0.90]) that were significantly higher than that of the RSBI (P = 0.017) and RSBI/DE (P < 0.001) in the same respective populations.

CONCLUSIONS

The RSBI and the ratio RSBI/DE failed to predict weaning success when measured during an SBT performed under minimal pressure support. Predictive indices incorporating ultrasound DE and DTF may merit further investigation.

Ventilator Parameters in the Diagnosis and Prognosis of Acute Respiratory Distress Syndrome in Postoperative Patients: A Preliminary Study

This study investigated the usefulness of ventilator parameters in the prediction of development and outcome of acute respiratory distress syndrome (ARDS) in postoperative patients with esophageal or lung cancer on admission to the surgical intensive care unit (SICU). A total of 32 post-operative patients with lung or esophageal cancer from SICU in a tertiary medical center were retrospectively analyzed. The study patients were divided into an ARDS group (n = 21) and a non-ARDS group (n = 11). The ARDS group contained the postoperative patients who developed ARDS after lung or esophageal cancer surgery. The ventilator variables were analyzed in this study. Principal component analysis (PCA) was performed to reduce the correlated ventilator variables to a small set of variables. The top three ventilator variables with large coefficients, as determined by PCA, were considered as sensitive variables and included in the analysis model based on the rule of 10 events per variable. Firth logistic regression with selective stepwise elimination procedure was performed to identify the most important predictors of morbidity and mortality in patients with ARDS. Ventilator parameters, including rapid shallow breath index during mechanical ventilation (RSBIv), rate pressure product of ventilation (RPPv), rate pressure volume index (RPVI), mechanical work (MW), and inspiration to expiration time ratio (IER), were analyzed in this study. It was found that the ARDS patients had significantly greater respiratory rate (RR), airway resistance (Raw), RSBIv, RPPv, RPVI, positive end-expiratory pressure (PEEP), and IER and significantly lower respiratory interval (RI), expiration time (Te), flow rate (V˙), tidal volume (V_T), dynamic compliance (Cdyn), mechanical work of ventilation (MW), and MW/IER ratio than the non-ARDS patients. The non-survivors of ARDS had significantly greater peak inspiratory pressure above PEEP (PIP), RSBIv, RPPv, and RPVI than the survivors of ARDS. By using PCA, the MW/IER was found to be the most important predictor of the development of ARDS, and both RPPv and RPVI were significant predictors of mortality in patients with ARDS. In conclusion, some ventilator parameters, such as RPPv, RPVI, and MW/IER defined in this study, can be derived from ventilator readings and used to predict the development and outcome of ARDS in mechanically ventilated patients on admission to the SICU.

Use of the Change in Weaning Parameters as a Predictor of Successful Re-Extubation

OBJECTIVE

Weaning parameters are well studied in patients undergoing first time extubation. Fewer data exists to guide re-extubation of patients who failed their first extubation attempt. It is reasonable to postulate that improved weaning parameters between the first and second extubation attempt would lead to improved rates of re-extubation success. To investigate, we studied a cohort of patients who failed their first extubation attempt and underwent a second attempt at extubation. We hypothesized that improvement in weaning parameters between the first and the second extubation attempt is associated with successful reextubation.

INTERVENTIONS

Rapid shallow breathing index (RSBI), maximum inspiratory pressure (MIP), vital capacity (VC), and the blood partial pressure of CO2 (PaCO2) were measured and recorded in the medical record prior to extubation along with demographic information. We examined the relationship between the change in extubation and re-extubation weaning parameters and re-extubation success.

MEASUREMENTS AND MAIN RESULTS

A total of 1283 adult patients were included. All weaning parameters obtained prior to re-extubation differed between those who were successful and those who required a second reintubation. Those with reextubation success had slightly lower PaCO2 values (39.5 ± 7.4 mmHg vs. 41.6 ± 9.1 mmHg, p = 0.0045) and about 13% higher vital capacity volumes (1021 ± 410 mL vs. 907 ± 396 mL, p = 0.0093). Lower values for RSBI (53 ± 32 breaths/min/L vs. 69 ± 42 breaths/min/L, p < 0.001) and MIP (-41 ± 12 cmH2O vs. -38 ± 13 cm H2O), p = 0.0225) were seen in those with re-extubation success. Multivariable logistical regression demonstrates lack of independent associated between the change in parameters between the 2 attempts and re-extubation success.

CONCLUSIONS

The relationship between the changes in extubation parameters through successive attempts is driven primarily by the value obtained immediately prior to re-extubation. These findings do not support waiting for an improvement in extubation parameters to extubate patients who failed a first attempt at extubation if extubation parameters are compatible with success.

Predictive value of the negative inspiratory force index as a predictor of weaning success: a crosssectional study

BACKGROUND

Identifying when intubated patients are ready to be extubated remains challenging. The negative inspiratory force (NIF) is a recommended predictor of weaning success. However, little is known about the role of NIF in the weaning process for the Asian surgical intensive population, especially for the Vietnamese population. Here, we aimed to investigate the cutoff threshold and predictive value of the NIF index for predicting the success of ventilator weaning in Vietnamese surgical intensive care patients.

METHODS

A cross-sectional study was conducted at the Surgical Intensive Care Unit of Viet Duc Hospital from October 2016 to August 2017. A total of 64 patients aged 16-70 years undergoing ventilatory support through an orotracheal tube satisfied the criteria for readiness to begin weaning. The correlation between the NIF index with outcomes of the weaning process was analyzed. Specificity (Sp), sensitivity (Se), positive predictive value (PPV), negative predictive value (NPV), receiver operating characteristic (ROC) curve, and area under the curve (AUC) were calculated.

RESULTS

The success rate of the entire weaning process was 67.2% (43/64). The median NIF values were -26.0 cm H2O (interquartile range [IQR], -28.0 to -25.0) in the successful weaning group and -24.0 cm H2O (IQR, -25.0 to -23.0) in the weaning failure group (P<0.001). According to ROC analysis, an NIF value ≤-25 cm H2O predicted weaning success (AUC, 0.836) with 91% Se, 62% Sp, 83% PPV, and 77% NPV.

CONCLUSIONS

An NIF cutoff threshold ≤-25 cm H2O can be used as predictor of weaning success in Vietnamese surgical intensive care patients.

Novel mechanical ventilator weaning predictive model

Mechanical ventilation (MV) is a common life support system in intensive care units. Accurate identification of patients who are capable of being extubated can shorten the MV duration and potentially reduce MV-related complications. Therefore, prediction of patients who can successfully be weaned from the mechanical ventilator is an important issue. The electronic medical record system (EMRs) has been applied and developed in respiratory therapy in recent years. It can increase the quality of critical care. However, there is no perfect index available that can be used to determine successful MV weaning. Our purpose was to establish a novel model that can predict successful weaning from MV. Patients' information was collected from the Kaohsiung Medical University Hospital respiratory therapy EMRs. In this retrospective study, we collected basic information, classic weaning index, and respiratory parameters during spontaneous breathing trials of patients eligible for extubation. According to the results of extubation, patients were divided into successful extubation and extubation failure groups. This retrospective cohort study included 169 patients. Statistical analysis revealed successful extubation predictors, including sex; height; oxygen saturation; Glasgow Coma Scale; Acute Physiology and Chronic Health Evaluation II score; pulmonary disease history; and the first, 30th, 60th, and 90th minute respiratory parameters. We built a predictive model based on these predictors. The area under the curve of this model was 0.889. We established a model for predicting the successful extubation. This model was novel to combine with serial weaning parameters and thus can help intensivists to make extubation decisions easily.

Evaluation of the association between decreased skeletal muscle mass and extubation failure after long-term mechanical ventilation

BACKGROUND & AIMS

Elderly patients are being increasingly admitted to the intensive care unit (ICU) for mechanical ventilation (MV) and prevalence of decreased skeletal muscle mass which develop with aging is subsequently increasing. The objective of this study was to identify the association between decreased skeletal muscle mass and extubation failure in patients undergoing long-term MV.

METHODS

Adults (≥18 years of age) with long-term MV for > 7 days between January 2014 and February 2019 were included retrospectively. Patients who died or were transferred with MV, underwent tracheostomy with failure of weaning from MV, and had not undergone abdominal computed tomography within 3 days before or after intubation were excluded. Failed extubation was defined as reintubation within 48 h after extubation following long-term MV for >7 days. We divided the patients into extubation success and failure groups.

RESULTS

Parameters including patients' demographics, cause of intubation, initial setting of MV, maximum inspiratory pressure (MIP) and rapid shallow breath index (RSBI) at extubation, and skeletal muscle mass were compared between the two groups. Decreased skeletal muscle mass was set a standard as a L3 muscle index of less than 49 cm²/m² for men and of less than 31 cm²/m² for women using Korean-specific cut-offs for sarcopenia as evaluated on previous epidemiologic study. Among 104 patients who were screened, 45 were included, and 11 (24.4%) failed to be extubated. Mean MIP (23.5 ± 11.8 vs. 32.4 ± 9.3, p = 0.134) and RSBI (57.2 ± 26.5 vs. 55.3 ± 20.4, p = 0.803) were not different between the two groups. The proportions of patients whose MIP or RSBI satisfied the cutoff for extubation were not different between the groups. There were no significant differences in age, sex, body mass index, comorbidities, nutritional status, and cause of intubation between the two groups. The extubation failure group showed a higher proportion of decreased skeletal muscle mass (90.9% vs. 58.8%, p = 0.05) and longer duration of MV (10.7 ± 4.1 vs. 9.6 ± 3.4, p < 0.001) than the extubation success group. Multivariate analysis showed that the duration of intubation (OR = 1.439, 95% CI = 1.12-1.85), and decreased skeletal muscle mass (OR = 24.382, 95% CI = 1.00-594.86) were associated with extubation failure.

CONCLUSIONS

Decreased skeletal muscle mass was associated with extubation failure after long-term MV for > 7 days. It is important to diagnose decreased skeletal muscle mass in critically ill patients to reduce extubation failure rates.

Use of excessive supplemental oxygen in mechanically ventilated patients is based on unit culture. A multiple-methods study in a regional intensive care unit

BACKGROUND

Administration of supplemental oxygen is widely used in the management of critically ill patients; however, there is evidence that excessive supplemental oxygen exposure is associated with increased mortality. There is limited research evaluating what factors clinicians take into consideration when managing oxygenation in critically ill adults.

OBJECTIVES

The purpose of this study was to explore intensive care unit (ICU) clinicians' experience and decision-making when managing supplemental oxygen therapy in mechanically ventilated patients in a regional intensive care unit.

METHODS

A multiple-methods observational study that included (i) a cross-sectional ICU staff survey and (ii) focus group discussions with critical care nurses was conducted. Descriptive statistics were used to summarise the key outcomes of the staff survey. Thematic analysis was used to analyse the focus group discussions and open-ended questions on the staff survey. The staff survey was completed by 49 ICU clinicians, and 11 critical care nurses participated in the two focus group discussions.

RESULTS

Survey data showed that staff acknowledged the problem of excessive oxygen exposure; 79.6% (n = 39) reported that the minimum acceptable fraction of inspired oxygen for mechanically ventilated patients was 0.3. The majority (89.8%, n = 44) reported that there was an interdisciplinary approach to decision-making in the unit. Two major themes were chosen from the focus group discussions and staff survey data: (i) Decision-making is based on unit culture rather than evidence and (ii) the process of weaning is driven by interdisciplinary team collaboration. Participants acknowledged that there needed to be a culture change from a liberal approach to oxygen therapy.

CONCLUSIONS

Although participants acknowledged the adverse consequences of excessive oxygen use, achieving oxygenation targets with the minimum level of supplemental oxygen was not a key focus of care. The findings highlight the need to develop and evaluate evidence-based protocols to support a conservative approach to supplemental oxygen management.

Predictive factors of weaning from mechanical ventilation and extubation outcome: A systematic review

PURPOSE

To identify, describe and discuss the parameters used to predict weaning from mechanical ventilation and extubation outcomes.

METHODS

Systematic review of scientific articles using four electronic databases: PubMed, Embase, PEDro and Cochrane Library. Search terms included "weaning", "extubation", "withdrawal" and "discontinuation", combined with "mechanical ventilation" and "predictive factors", "predictive parameters" and "predictors for success". In this study, we included original articles that presented predictive factors for weaning or extubation outcomes in adult patients and not restricted to a single disease. Articles not written in English were excluded.

RESULTS

A total of 43 articles were included, with a total of 7929 patients and 56 different parameters related to weaning and extubation outcomes. Rapid Shallow Breathing Index (RSBI) was the most common predictor, discussed in 15 studies (2159 patients), followed by Age and Maximum Inspiratory Pressure in seven studies. The other 53 parameters were found in less than six studies.

CONCLUSION

There are several parameters used to predict weaning and extubation outcomes. RSBI was the most frequently studied and seems to be an important measurement tool in deciding whether to wean/extubate a patient. Furthermore, the results demonstrated that weaning and extubation should be guided by several parameters, and not only to respiratory ones.

The impact of heart, lung and diaphragmatic ultrasound on prediction of failed extubation from mechanical ventilation in critically ill patients: a prospective observational pilot study

Background

Failed extubation from mechanical ventilation in critically ill patients is multifactorial, complex and not well understood. We aimed to identify whether combined transthoracic echocardiography, lung and diaphragmatic ultrasound can predict extubation failure in critically ill patients.

Results

Fifty-three participants who were intubated > 48 h and deemed by the treating intensivist ready for extubation underwent a 60-min pre-extubation weaning trial (pressure support ≤ 10 cmH₂O and positive end expiratory pressure 5 cmH₂O). Prior to extubation, data collected included ultrasound assessment of left ventricular ejection fraction, left atrial area, early diastolic trans-mitral flow velocity wave (E), early diastolic trans-mitral flow velocity wave/late diastolic trans-mitral flow velocity wave (E/A), early diastolic trans-mitral flow velocity wave/early diastolic mitral annulus velocity (E/E′), interatrial septal motion, lung loss of aeration score and diaphragm movement. At the end of the weaning trial, the rapid shallow breathing index and serum B-type natriuretic peptide concentration were measured. Success and failure of weaning was assessed by defined criteria. Decision to extubate was at the discretion of the treating intensivist. Failure of extubation was defined as re-intubation, non-invasive ventilation or death within 48 h after extubation. Of 53 extubated participants, 11 failed extubation. Failed extubation was associated with diabetes, ischaemic heart disease, higher E/E′ (OR 1.27, 95% CI 1.05–1.54), left atrial area (OR 1.14, CI 1.02–1.28), fixed rightward curvature of the interatrial septum (OR 12.95, CI 2.73–61.41), and higher loss of aeration score of anterior and lateral regions of the lungs (OR 1.41, CI 1.01–1.82).

Conclusions

Failed extubation in mechanically ventilated patients is more prevalent if markers of left ventricular diastolic dysfunction and loss of lung aeration are present.

Use of diaphragm thickening fraction combined with rapid shallow breathing index for predicting success of weaning from mechanical ventilator in medical patients

Background

Weaning failure is a crucial hindrance in critically ill patients. Rapid shallow breathing index (RSBI), a well-known weaning index, has some limitations in predicting weaning outcomes. A new weaning index using point-of-care ultrasound with diaphragmic thickening fraction (DTF) has potential benefits for improving weaning success. The aim of this study was to evaluate the efficacy of a combination of DTF and RSBI for predicting successful weaning compared to RSBI alone.

Methods

This prospective study enrolled patients from the medical intensive care unit or ward who were using mechanical ventilation and readied for weaning. Patients underwent a spontaneous breathing trial (SBT) for 1 h, and then, both hemi-diaphragms were visualized in the zone of apposition using a 10-MHz linear probe. Diaphragm thickness was recorded at the end of inspiration and expiration which supposed the lung volume equal to total lung capacity (TLC) and residual volume (RV), respectively, and the DTF was calculated as a percentage from this formula: thickness at TLC minus thickness at RV divided by thickness at RV. In addition, RSBI was calculated at 1 min after SBT. Weaning failure was defined as the inability to maintain spontaneous breathing within 48 h.

Results

Of the 34 patients enrolled, the mean (± SD) age was 66.5 (± 13.5) years. There were 25 patients with weaning success, 9 patients in the weaning failure group. The receiver operating characteristic curves of right and left DTF and the RSBI for the prediction of successful weaning were 0.951, 0.700, and 0.709, respectively. The most accurate cutoff value for prediction of successful weaning was right DTF ≥ 26% (sensitivity of 96%, specificity of 68%, positive predictive value of 89%, negative predictive value of 86%). The combination of right DTF ≥ 26% and RSBI ≤ 105 increased specificity to 78% but slightly decreased sensitivity to 92%. Intra-observer correlation increased sharply to almost 0.9 in the first ten patients and slightly increased after that.

Conclusions

Point-of-care ultrasound to assess diaphragm function has an excellent learning curve and helps physicians determine weaning readiness in critically ill patients. The combination of right DTF and RSBI greatly improved the accuracy for prediction of successful weaning compared to RSBI alone.

Trial registration

Thai Clinical Trials Registry, TCTR20171025001. Retrospectively registered on October 23, 2017.

Mechanical ventilation weaning protocol improves medical adherence and results

INTRODUCTION

Implementation of a weaning protocol is related to better patient prognosis. However, new approaches may take several years to become the standard of care in daily practice. We conducted a prospective cohort study to investigate the effectiveness of a multifaceted strategy to implement a protocol to wean patients from mechanical ventilation (MV) and to evaluate the weaning success rate as well as practitioner adherence to the protocol.

METHODS

We investigated all consecutive MV-dependent subjects admitted to a medical-surgical intensive care unit (ICU) for >24h over 7years. The multifaceted strategy consisted of continuing education of attending physicians and ICU staff and regular feedback regarding patient outcomes. The study was conducted in three phases: protocol development, protocol and multifaceted strategy implementation, and protocol monitoring. Data regarding weaning outcomes and physician adherence to the weaning protocol were collected during all phases.

RESULTS

We enrolled 2469 subjects over 7years, with 1,943 subjects (78.7%) experiencing weaning success. Physician adherence to the protocol increased during the years of protocol and multifaceted strategy implementation (from 38% to 86%, p<0.01) and decreased in the protocol monitoring phase (from 73.9% to 50.0%, p<0.01). However, during the study years, the weaning success of all subjects increased (from 73.1% to 85.4%, p<0.001). When the weaning protocol was evaluated step-by-step, we found high adherence for noninvasive ventilation use (95%) and weaning predictor measurement (91%) and lower adherence for control of fluid balance (57%) and daily interruption of sedation (24%). Weaning success was higher in patients who had undergone the weaning protocol compared to those who had undergone weaning based in clinical practice (85.6% vs. 67.7%, p<0.001).

CONCLUSIONS

A multifaceted strategy consisting of continuing education and regular feedback can increase physician adherence to a weaning protocol for mechanical ventilation.