A randomized, controlled trial of the role of weaning predictors in clinical decision making

Comparison of Spontaneous Breathing Trials in Clinical Practice and Current Clinical Practice Guidelines

Background: The literature suggests there is variability in the clinical practice of spontaneous breathing trials (SBTs). Evidence-based literature and clinical practice guidelines (CPGs) have been published over time to address various aspects of SBT implementation. It can take many years for evidence-based recommendations to be adopted into clinical practice. The American Association for Respiratory Care recently published a CPG addressing 4 aspects of SBT implementation. Methods: This study evaluated how the clinical practice of SBTs compares to the recommendations of the CPG. An online survey was developed to assess how hospitals with SBT protocols perform different components of SBTs. Descriptive statistics were used in the data analysis. Results: A total of 26 representatives from different health care institutions in the United States met the criteria for data analysis; 61.5% of reported protocols use rapid shallow breathing index, which is not in alignment with the current recommendation; 77% reported the use of pressure support (PS); 11.5% specified the use of a T-piece, and 11% specified the option of either PS or T-piece during the SBT. The responses were 100% in alignment with the current recommendation of performing a SBT with or without support; 73.1% aligned with having a standardized approach to performing SBTs by specifying when the SBT will be initiated; 65.4% perform an SBT during the day, though it was not specified if it occurs before noon each day; 53.8% allow for an increase in FIO2 during an SBT, which is not in alignment with the current recommendations. Conclusions: The reported hospitals' protocols demonstrated moderate alignment with the 4 CPG recommendations. Identifying current discrepancies between clinical practice and CPGs will allow for the assessment of the adoption of recommendations into clinical practice over time. Further assessment could be performed to determine if there is an impact on patient outcomes.

Predictive Value of Serial Rapid Shallow Breathing Index Measurements for Extubation Success in Intensive Care Unit Patients

Background and Objectives: Extubation success in ICU patients is crucial for reducing ventilator-associated complications, morbidity, and mortality. The Rapid Shallow Breathing Index (RSBI) is a widely used predictor for weaning from mechanical ventilation. This study aims to determine the predictive value of serial RSBI measurements on extubation success in ICU patients on mechanical ventilation. Materials and Methods: This prospective observational study was conducted on 86 ICU patients at Hitit University between February 2024 and July 2024. Patients were divided into successful and unsuccessful extubation groups. RSBI values were compared between these groups. Results: This study included 86 patients (32 females, 54 males) with a mean age of 54.51 ± 12.1 years. Extubation was successful in 53 patients and unsuccessful in 33. There was no significant difference in age and intubation duration between the groups (p = 0.246, p = 0.210). Significant differences were found in RSBI-1a and RSBI-2 values (p = 0.013, p = 0.011). The median RSBI-2a was 80 in the successful group and 92 in the unsuccessful group (p = 0.001). The ΔRSBI was higher in the unsuccessful group (p = 0.022). ROC analysis identified optimal cut-off values: RSBI-2a ≤ 72 (AUC 0.715) and ΔRSBI ≤ -3 (AUC 0.648). RSBI-2a ≤ 72 increased the likelihood of successful extubation by 10.8 times, while ΔRSBI ≤ -3 increased it by 3.4 times. Using both criteria together increased the likelihood by 28.48 times. Conclusions: Serial RSBI measurement can be an effective tool for predicting extubation success in patients on IMV. These findings suggest that serially measured RSBI may serve as a potential indicator for extubation readiness.

Ventilator Weaning and Extubation

Increasing evidence supports specific approaches to liberate patients from invasive ventilation including the use of liberation protocols, inspiratory assistance during spontaneous breathing trials (SBTs), early extubation of patients with chronic obstructive pulmonary disease to noninvasive ventilation, and prophylactic use of noninvasive support strategies after extubation. Additional research is needed to elucidate the best criteria to identify patients who are ready to undergo an SBT and to inform optimal screening frequency, the best SBT technique and duration, extubation assessments, and extubation decision-making. Additional clarity is also needed regarding the optimal timing to measure and report extubation success.

Sex difference in the risk of extubation failure in ICUs

BACKGROUND

Little attention has been paid to potential differences in prognosis between mechanically ventilated males and females in intensive care units (ICUs). We hypothesized that a sex gap in the risk of extubation failure in ICUs may exist.

METHODS

Post hoc analysis of a large-scale clinical trial including patients at high risk of extubation failure in ICUs, with the aim of assessing the risk of extubation failure according to sex. The primary outcome was reintubation within the 7 days following extubation.

RESULTS

Out of 641 patients, 425 (66%) were males and 216 (34%) were females. Males were more likely to be admitted for cardiac arrest and to have underlying ischemic heart disease whereas females were more likely to be admitted for coma and to have obesity. Whereas the rate of reintubation at 48 h was significantly higher in males than in females (11.0% vs. 6.0%; difference, + 5.0 [95% CI, 0.2 to 9.2]; P = 0.038), the rate of reintubation at day 7 did not significantly differ between males and females (16.7% vs. 11.1%; difference, + 5.6% [95%CI, - 0.3 to 10.8], P = 0.059). Using multivariable logistic regression analysis, male sex was independently associated with reintubation within the 7 days following extubation (adjusted OR 1.70 [95% CI, 1.01 to 2.89]; P = 0.048), even after adjustment on reason for admission, body-mass index, severity score, respiratory rate before extubation, and noninvasive ventilation after extubation.

CONCLUSION

In this post hoc analysis of a clinical trial including a homogeneous subset of patients at high risk of extubation failure, sex was independently associated with reintubation. The role of sex on outcomes should be systematically examined in future studies of critically ill patients.

Liberation From Venovenous Extracorporeal Membrane Oxygenation for Respiratory Failure: A Scoping Review

BACKGROUND

Safe and timely liberation from venovenous extracorporeal membrane oxygenation (ECMO) would be expected to reduce the duration of ECMO, the risk of complications, and costs. However, how to liberate patients from venovenous ECMO effectively remains understudied.

RESEARCH QUESTION

What is the current state of the evidence on liberation from venovenous ECMO?

STUDY DESIGN AND METHODS

We systematically searched for relevant publications on liberation from venovenous ECMO in Medline and EMBASE. Citations were included if the manuscripts provided any of the following: criteria for readiness for liberation, a liberation protocol, or a definition of successful decannulation or decannulation failure. We included randomized trials, observational trials, narrative reviews, guidelines, editorials, and commentaries. We excluded single case reports and citations where the full text was unavailable.

RESULTS

We screened 1,467 citations to identify 39 key publications on liberation from venovenous ECMO. We then summarized the data into five main topics: current strategies used for liberation, criteria used to define readiness for liberation, conducting liberation trials, criteria used to proceed with decannulation, and parameters used to predict decannulation outcomes.

INTERPRETATION

Practices on liberation from venovenous ECMO are heterogeneous and are influenced strongly by clinician preference. Additional research on liberation thresholds is needed to define optimal liberation strategies and to close existing knowledge gaps in essential topics on liberation from venovenous ECMO.

Emerging Applications of Extracardiac Ultrasound in Critically Ill Cardiac Patients

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

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.

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.

To Wean or Not to Wean: A Practical Patient Focused Guide to Ventilator Weaning

Since the inception of critical care medicine and artificial ventilation, literature and research on weaning has transformed daily patient care in intensive care units (ICU). As our knowledge of mechanical ventilation (MV) improved, so did the need to study patient-ventilator interactions and weaning predictors. Randomized trials have evaluated the use of protocol-based weaning (vs. usual care) to study the duration of MV in ICUs, different techniques to conduct spontaneous breathing trials (SBT), and strategies to eventually extubate a patient whose initial SBT failed. Despite considerable milestones in the management of multiple diseases contributing to reversible respiratory failure, in the application of early rehabilitative interventions to preserve muscle integrity, and in ventilator technology that mitigates against ventilator injury and dyssynchrony, major barriers to successful liberation from MV persist. This review provides a broad encompassing view of weaning classification, causes of weaning failure, and evidence behind weaning predictors and weaning modes.

Liberation from Mechanical Ventilation: Established and New Insights

A substantial proportion of critically ill patients require ventilator support with the majority requiring invasive mechanical ventilation. Timely and safe liberation from invasive mechanical ventilation is a critical aspect of patient care in the intensive care unit (ICU) and is a top research priority for patients and clinicians. In this article, we discuss how to (1) identify candidates for liberation from mechanical ventilation, (2) conduct spontaneous breathing trials (SBTs), and (3) optimize patients for liberation from mechanical ventilation. We also discuss the roles for (4) extubation to noninvasive ventilation and (5) newer modes of mechanical ventilation during liberation from mechanical ventilation. We conclude that, though substantial progress has been made in identifying patients who are likely to be liberated (e.g., through the use of SBTs) and management strategies that speed liberation from the ventilator (e.g., protocolized SBTs, lighter sedation, and early mobilization), many important questions regarding liberation from mechanical ventilation in clinical practice remain unanswered.

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.

Biosignal-Based Digital Biomarkers for Prediction of Ventilator Weaning Success

We evaluated new features from biosignals comprising diverse physiological response information to predict the outcome of weaning from mechanical ventilation (MV). We enrolled 89 patients who were candidates for weaning from MV in the intensive care unit and collected continuous biosignal data: electrocardiogram (ECG), respiratory impedance, photoplethysmogram (PPG), arterial blood pressure, and ventilator parameters during a spontaneous breathing trial (SBT). We compared the collected biosignal data's variability between patients who successfully discontinued MV (n = 67) and patients who did not (n = 22). To evaluate the usefulness of the identified factors for predicting weaning success, we developed a machine learning model and evaluated its performance by bootstrapping. The following markers were different between the weaning success and failure groups: the ratio of standard deviations between the short-term and long-term heart rate variability in a Poincaré plot, sample entropy of ECG and PPG, α values of ECG, and respiratory impedance in the detrended fluctuation analysis. The area under the receiver operating characteristic curve of the model was 0.81 (95% confidence interval: 0.70-0.92). This combination of the biosignal data-based markers obtained during SBTs provides a promising tool to assist clinicians in determining the optimal extubation time.

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

Objectives:

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

Methods:

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

Results:

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

Conclusions:

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

Predictors of asynchronies during assisted ventilation and its impact on clinical outcomes: The EPISYNC cohort study

PURPOSE

To investigate if respiratory mechanics and other baseline characteristics are predictors of patient-ventilator asynchrony and to evaluate the relationship between asynchrony during assisted ventilation and clinical outcomes.

METHODS

We performed a prospective cohort study in patients under mechanical ventilation (MV). Baseline measurements included severity of illness and respiratory mechanics. The primary outcome was the Asynchrony Index (AI), defined as the number of asynchronous events divided by the number of ventilator cycles and wasted efforts. We recorded ventilator waveforms throughout the entire period of MV.

RESULTS

We analyzed 11,881 h of MV from 103 subjects. Median AI during the entire period of MV was 5.1% (IQR:2.6-8.7). Intrinsic PEEP was associated with AI (OR:1.72, 95%CI:1.1-2.68), but static compliance and airway resistance were not. Simplified Acute Physiology Score 3 (OR:1.03, 95%CI:1-1.06) was also associated with AI. Median AI was higher during assisted (5.4%, IQR:2.9-9.1) than controlled (2%, IQR:0.6-4.9) ventilation, and 22% of subjects had high incidence of asynchrony (AI≥10%). Subjects with AI≥10% had more extubation failure (33%) than patients with AI<10% (6%), p = .01.

CONCLUSIONS

Predictors of high incidence of asynchrony were severity of illness and intrinsic PEEP. High incidence of asynchrony was associated with extubation failure, but not mortality.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02687802.

Ultrasonographic evaluation of lung and heart in predicting successful weaning in mechanically ventilated neurosurgical patients

In critically ill neurosurgical patients, delayed and premature extubation increases the risk of morbidity and mortality. Assessment of critically ill patients before and during spontaneous breathing trial (SBT) is crucial in predicting weaning failure. We explored the trend of changes with integrated lung and cardiac ultrasonography in predicting success of weaning in neurosurgical patients. Lung ultrasound and cardiac ultrasound was performed before and after 30 min and 120 min of SBT. Lung ultrasound score (LUS, range 0–36) was calculated using a predefined method of assessment of six chest regions on either side. The left ventricular function was evaluated by measuring fractional area change. The maximum velocities of mitral inflow E and A waves (E/A), deceleration time of E wave (DTE) and tissue doppler based E′ wave at lateral annulus to calculate E/E′, were measured to assess left ventricular filling pressure. Twenty seven patients underwent SBT, among these 22 had success and five had failure of SBT. The SBT failure group had higher baseline LUS and progressively higher LUS during SBT compared to the success group, suggesting significant lung de-recruitment. There was significant increase in the LV filling pressure (increase E/A and E/E′, decrease in DTE) after 30 and 120 min of SBT in failure group compared to the success group. Point of care lung and cardiac ultrasonography may be useful in detecting cardiopulmonary changes induced by SBT. Higher lung aeration loss and LV filling pressure were observed with SBT failure group.

Effect of Using the Rapid Shallow Breathing Index as Readiness Criterion for Spontaneous Breathing Trials in a Weaning Protocol

BACKGROUND

This study aimed to compare the effect of using versus not using the Rapid-Shallow Breathing Index (RSBI) as a readiness criterion for Spontaneous Breathing Trials (SBT) on SBT success.

MATERIALS AND METHODS

Daily readiness screens were performed within a respiratory therapist-driven weaning protocol. Patients who passed these screens underwent a one-time measurement of the RSBI and then a SBT regardless of RSBI result. The proportion of passed readiness screens reaching SBT success was compared to the proportion that would have been obtained if RSBI ≤ 105 br/min/L had been used as an additional screen criterion.

RESULTS

Two hundred and fifty SBTs performed on 157 patients were analyzed. The sensitivity of RSBI ≤ 105 br/min/L to predict SBT success was 94.8% (95% CI 90.6-97.5). Relative to potentially using RSBI, 14.4% additional SBTs were performed. A third of these were successful, and no complications were detected in the rest that failed. The proportion of passed readiness screens reaching SBT success would have been 4% (95% CI 1.2-6.8) (P = 0.002) lower if RSBI had been used.

CONCLUSIONS

The inclusion of the RSBI in a readiness screen may not be useful in a weaning protocol.

Ventilatory equivalent for oxygen as an extubation outcome predictor: A pilot study

Introduction

Weaning predictors can help liberate patients in a timely manner from mechanical ventilation. Ventilatory equivalent for oxygen (VEqO₂), a surrogate for work of breathing and a measure of the efficiency of breathing, may be an important noninvasive alternative to other weaning predictors. Our study’s purpose was to observe any differences in VEqO₂ between extubation outcome groups.

Methods

Employing a metabolic cart, oxygen consumption (V^˙O₂), minute volume (VE), tidal volume (VT), and breathing frequency were recorded during a spontaneous breathing trial (SBT) to calculate VEqO₂ and the rapid shallow breathing index (RSBI) in 34 adult participants in the intensive care unit. Five-breath means of VEqO₂ and the RSBI collected throughout the SBT were examined between SBT pass and fail groups and extubation pass and fail groups using the Mann–Whitney U test with p < 0.05.

Results

Data from 31 participants were analyzed between SBT outcome groups. Data from 20 participants were examined for extubation outcome after a successful SBT. Median (interquartile range) VEqO₂ was not different between extubation groups. Participants who passed the SBT had a higher median VEqO₂ than those who did not at the midpoint (25.3 L/L V^˙O₂ [22–33 L/L V^˙O₂] vs. 23.7 L/L V^˙O₂ [18–24 L/L V^˙O₂], p = 0.035) and at the end (25.5 L/L V^˙O₂ [23–34 L/L V^˙O₂] vs. 21.3 L/L V^˙O₂ [20–24 L/L V^˙O₂], p = 0.017) of the SBT.

Discussion

VEqO₂ may show differences in SBT outcomes, but not differences between extubation outcomes. VEqO₂ may be able to detect differences in work during an SBT, but may not be able to predict change in workload in the respiratory system after extubation. The small sample size may also have prevented any differences in extubation outcomes to be shown.

Conclusion

VEqO₂ was higher in patients that passed their SBT. VEqO₂ was not useful in identifying extubation success or failure in adult mechanically ventilated patients.

Evaluation of airway care score as a criterion for extubation in patients admitted in neurosurgery intensive care unit

Background and Aims:

Early extubation in neurocritical patients has several potential benefits. Glasgow Coma Scale (GCS) is a crude measure of neurologic function in these patients and a low GCS score does not necessarily mean contraindication for extubation. Data on patients with neurosurgical or neurological pathology undergoing early extubation utilizing the airway score criteria is limited. Hence, this study was conceived to assess the usefulness of modified airway care score (ACS) as a criterion for successful extubation of neurocritical patients whilst comparing various outcomes.

Material and Methods:

One hundred and twenty four patient who underwent endotracheal intubation in the neurocritical care unit were enrolled in this prospective observational study over a period of 12 months. Patients were randomly enrolled into either the study group patients (S), who were extubated immediately after a successful spontaneous breathing trial (SBT) and an ACS ≤7 or into the control group (N), wherein patients were extubated/tracheostomized at discretion of the attending neurointensivist. Both groups were observed for comparison of preset outcomes and analyzed statistically.

Results:

Patients of study group experienced a statistically significant shorter extubation delay (3.28 h vs 25.41 h) compared to the control group. Successful extubation rate was significantly higher and reintubation rate was significantly lower in study group (6.6% vs 29.3%). Incidence of nosocomial pneumonia, duration of ICU stay and overall duration of mechanical ventilation were significantly lower in the study group. ACS and GCS had a negative correlation at the time of extubation.

Conclusion:

ACS can be used as a criterion for successful early extubation of neurocritical patients.

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.

Ultrasound assessment of diaphragmatic dysfunction as a predictor of weaning outcome from mechanical ventilation: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review was to assess the diaphragmatic dysfunction (DD) as a predictor of weaning outcome.

BACKGROUND

Successful weaning depends on several factors: muscle strength, cardiac, respiratory and metabolic. Acquired weakness in mechanical ventilation is a growing important cause of weaning failure. With the development of ultrasonography, DD can be evaluated with ultrasound in weakness patients to predict weaning outcomes.

METHODS

The Cochrane Library, PubMed, Embase, Ovid Medline, WanFang Data and CNKI were systematically searched from the inception to September 2017. Ultrasound assessment of DD in adult mechanical ventilation patients was included. Two independent investigators assessed study quality in accordance with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome was diaphragmatic thickness and excursion in the weaning success and failure group. The secondary outcome was the influence of DD on weaning outcome.

RESULTS

Eleven studies involving a total of 436 patients were included. There were eight studies comparing diaphragmatic excursion (DE), five comparing the diaphragmatic thickening fraction (DTF) and two comparing DD between groups with and without successful weaning. Overall, the DE or DTF had a pooled sensitivity of 0.85 (95% CI 0.77 to 0.91) and a pooled specificity of 0.74 (95% CI 0.66 to 0.80) for predicting weaning success. There was high heterogeneity among the included studies (I²=80%; p=0.0006). The rate of weaning failure was significantly increased in patients with DD (OR 8.82; 95% CI 3.51 to 22.13; p<0.00001).

CONCLUSIONS

Both DE and DTF showed good diagnostic performance to predict weaning outcomes in spite of limitations included high heterogeneity among the studies. DD was found to be a predictor of weaning failure in critically ill patients.

Pressure-support ventilation or T-piece spontaneous breathing trials for patients with chronic obstructive pulmonary disease - A randomized controlled trial

Background

Little is known about the best strategy for weaning patients with chronic obstructive pulmonary disease (COPD) from mechanical ventilation. Spontaneous breathing trials (SBT) using a T-piece or pressure-support ventilation (PSV) have a central role in this process. Our aim was to compare T-piece and PSV SBTs according to the duration of mechanical ventilation (MV) in patients with COPD.

Methods

Patients with COPD who had at least 48 hours of invasive MV support were randomized to 30 minutes of T-piece or PSV at 10 cm H₂O after being considered able to undergo a SBT. All patients were preemptively connected to non-invasive ventilation after extubation. Tracheostomized patients were excluded. The primary outcome was total invasive MV duration. Time to liberation from MV was assessed as secondary outcome.

Results

Between 2012 and 2016, 190 patients were randomized to T-piece (99) or PSV (91) groups. Extubation at first SBT was achieved in 78% of patients. The mean total MV duration was 10.82 ± 9.1 days for the T-piece group and 7.31 ± 4.9 days for the PSV group (p < 0.001); however, the pre-SBT duration also differed (7.35 ± 3.9 and 5.84 ± 3.3, respectively; p = 0.002). The time to liberation was 8.36 ± 11.04 days for the T-piece group and 4.06 ± 4.94 for the PSV group (univariate mean ratio = 2.06 [1.29–3.27], p = 0.003) for the subgroup of patients with difficult or prolonged weaning. The study group was independently associated with the time to liberation in this subgroup.

Conclusions

The SBT technique did not influence MV duration for patients with COPD. For the difficult/prolonged weaning subgroup, the T-piece may be associated with a longer time to liberation, although this should be clarified by further studies.

Trial registration

ClinicalTrials.gov NCT01464567, at November 3, 2011.

A Decision for Predicting Successful Extubation of Patients in Intensive Care Unit

Approximately 40% of patients admitted to the medical intensive care unit (ICU) require mechanical ventilation. An accurate prediction of successful extubation in patients is a key clinical problem in ICU due to the fact that the successful extubation is highly associated with prolonged ICU stay. The prolonged ICU stay is also associated with increasing cost and mortality rate in healthcare system. This study is retrospective in the aspect of ICU. Hence, a total of 41 patients were selected from the largest academic medical center in Taiwan. Our experimental results show that predicting successful rate of 87.8% is obtained from the proposed predicting function. Based on several types of statistics analysis, including logistic regression analysis, discriminant analysis, and bootstrap method, three major successful extubation predictors, namely, rapid shallow breathing index, respiratory rate, and minute ventilation, are revealed. The prediction of successful extubation function is proposed for patients, ICU, physicians, and hospital for reference.

Vagal withdrawal and psychological distress during ventilator weaning and the related outcomes

OBJECTIVE

This study investigated the associations between changes in autonomic nervous system (ANS) function, psychological status during the mechanical ventilation (MV) weaning process, and weaning outcomes.

METHODS

In this prospective study, we recruited 67 patients receiving MV for >24h at a medical center in northern Taiwan. Patients' ANS function, represented by heart rate variability (HRV), the rapid shallow breathing index (RSBI), anxiety, fear, and dyspnea, was repeatedly measured 10min before and 30min after undergoing a weaning trial. Forty-nine patients capable of sustaining a 2-h weaning trial were successfully weaned.

RESULTS

Compared with the failed group, the success group showed significantly smaller decreases in high-frequency HRV (HRV-HF) and smaller increases in RSBI (per 10 breaths/min/L), fear, dyspnea, and anxiety in response to the weaning trial (odds ratio [OR]=2.19, 0.81, 0.69, 0.66, and 0.77, respectively; p<0.05). Multivariate analyses revealed that low-frequency HRV before weaning (OR=2.32; 95% confidence interval [CI]=1.13-4.78, p=0.02), changes in HRV-HF (OR=3.33; 95% CI=1.18-9.44, p=0.02), and psychological fear during the weaning process (OR=0.50; 95% CI=0.27-0.92, p=0.03) were three independent factors associated with 2-h T-piece weaning success.

CONCLUSIONS

ANS responses and psychological distress during weaning were associated with T-piece weaning outcomes and may reflect the need for future studies to utilize these factors to guide weaning processes and examine their impact on outcomes.

Simple motor tasks independently predict extubation failure in critically ill neurological patients

Objective:

To evaluate the usefulness of simple motor tasks such as hand grasping and tongue protrusion as predictors of extubation failure in critically ill neurological patients.

Methods:

This was a prospective cohort study conducted in the neurological ICU of a tertiary care hospital in the city of Porto Alegre, Brazil. Adult patients who had been intubated for neurological reasons and were eligible for weaning were included in the study. The ability of patients to perform simple motor tasks such as hand grasping and tongue protrusion was evaluated as a predictor of extubation failure. Data regarding duration of mechanical ventilation, length of ICU stay, length of hospital stay, mortality, and incidence of ventilator-associated pneumonia were collected.

Results:

A total of 132 intubated patients who had been receiving mechanical ventilation for at least 24 h and who passed a spontaneous breathing trial were included in the analysis. Logistic regression showed that patient inability to grasp the hand of the examiner (relative risk = 1.57; 95% CI: 1.01-2.44; p < 0.045) and protrude the tongue (relative risk = 6.84; 95% CI: 2.49-18.8; p < 0.001) were independent risk factors for extubation failure. Acute Physiology and Chronic Health Evaluation II scores (p = 0.02), Glasgow Coma Scale scores at extubation (p < 0.001), eye opening response (p = 0.001), MIP (p < 0.001), MEP (p = 0.006), and the rapid shallow breathing index (p = 0.03) were significantly different between the failed extubation and successful extubation groups.

Conclusions:

The inability to follow simple motor commands is predictive of extubation failure in critically ill neurological patients. Hand grasping and tongue protrusion on command might be quick and easy bedside tests to identify neurocritical care patients who are candidates for extubation.

Behavior of lung ultrasound findings during spontaneous breathing trial

OBJECTIVE

We aimed to investigate a potential association between B-lines and weaning failure.

METHODS

Fifty-seven subjects eligible for ventilation liberation were enrolled. Patients with tracheostomy were excluded. Lung ultrasound assessments of six thoracic zones were performed immediately before and at the exnd of the spontaneous breathing trial. B-predominance was defined as any profile with anterior bilateral B-pattern. Patients were followed up to 48 hours after extubation.

RESULTS

Thirty-eight individuals were successfully extubated; 11 failed the spontaneous breathing trial and 8 needed reintubation within 48 hours of extubation. At the beginning of the T-piece trial, B-pattern or consolidation was already found at the lower and posterior lung regions in more than half of the individuals and remained non-aerated at the end of the trial. A trend toward loss of lung aeration during spontaneous breathing trials was observed only in the spontaneous breathing trial-failure group (p = 0.07), and there was higher B-predominance at the end of the trial (p = 0.01).

CONCLUSION

A loss of lung aeration during the spontaneous breathing trial in non-dependent lung zones was demonstrated in subjects who failed to wean.

Development of a risk score to predict extubation failure in patients with traumatic brain injury

PURPOSE

To identify predictors and develop a risk score for the prediction of extubation failure in TBI patients.

MATERIALS AND METHODS

We prospectively evaluated 311 TBI adults receiving mechanical ventilation for >48h in the intensive care unit. Epidemiological, ventilatory, airway protective, laboratory, and hemodynamic predictors were evaluated. A multiple logistic regression model was developed to predict the extubation failure risk. A score was developed using the arithmetic sum of the points for each independent predictor, whose scores were proportional to the regression coefficient. The accuracy of the model was determined using the C statistic.

RESULTS

Extubation failure occurred in 43 patients (13.8%). Five independent predictors were identified: female sex (4 points) Glasgow Coma Scale motor score≤5 (4 points), moderate-to-large secretion volume (4 points), absent or weak cough (3 points), and mechanical ventilation≥10days (2 points). We calculated the risk score for patients and three risk categories were defined: low (0-3 points), moderate (4-7 points), high (8-17 points). The extubation failure rates in the three groups were 3.5%, 21.2%, and 42.9%, respectively.

CONCLUSION

The score developed to predict extubation failure in TBI patients can identify three risk categories and can be easily applied in the ICU.

Plasma Concentrations of Soluble Suppression of Tumorigenicity-2 and Interleukin-6 Are Predictive of Successful Liberation From Mechanical Ventilation in Patients With the Acute Respiratory Distress Syndrome

OBJECTIVES

Soluble suppression of tumorigenicity-2 and interleukin-6 concentrations have been associated with the inflammatory cascade of acute respiratory distress syndrome. We determined whether soluble suppression of tumorigenicity-2 and interleukin-6 levels can be used as prognostic biomarkers to guide weaning from mechanical ventilation and predict the need for reintubation.

DESIGN, SETTING, AND PATIENTS

We assayed plasma soluble suppression of tumorigenicity-2 (n = 826) concentrations and interleukin-6 (n = 755) concentrations in the Fluid and Catheter Treatment Trial, a multicenter randomized controlled trial of conservative fluid management in acute respiratory distress syndrome. We tested whether soluble suppression of tumorigenicity-2 and interleukin-6 levels were associated with duration of mechanical ventilation, the probability of passing a weaning assessment, and the need for reintubation.

MEASUREMENTS AND MAIN RESULTS

In models adjusted for Acute Physiology and Chronic Health Evaluation score and other relevant variables, patients with higher day 0 and day 3 median soluble suppression of tumorigenicity-2 and interleukin-6 concentrations had decreased probability of extubation over time (day 0 soluble suppression of tumorigenicity-2: hazard ratio, 0.85; 95% CI, 0.72-1.00; p = 0.05; day 0 interleukin-6: hazard ratio, 0.64; 95% CI, 0.54-0.75; p < 0.0001; day 3 soluble suppression of tumorigenicity-2: hazard ratio, 0.64; 95% CI, 0.54-0.75; p < 0.0001; and day 3 interleukin-6: hazard ratio, 0.73; 95% CI, 0.62-0.85; p = 0.0001). Higher biomarker concentrations were also predictive of decreased odds of passing day 3 weaning assessments (soluble suppression of tumorigenicity-2: odds ratio, 0.62: 95% CI, 0.44-0.87; p = 0.006 and interleukin-6: odds ratio, 0.61; 95% CI, 0.43-0.85; p = 0.004) and decreased odds of passing a spontaneous breathing trial (soluble suppression of tumorigenicity-2: odds ratio, 0.45; 95% CI, 0.28-0.71; p = 0.0007 and interleukin-6 univariate analysis only: odds ratio, 0.55; 95% CI, 0.36-0.83; p = 0.005). Finally, higher biomarker levels were significant predictors of the need for reintubation for soluble suppression of tumorigenicity-2 (odds ratio, 3.23; 95% CI, 1.04-10.07; p = 0.04) and for interleukin-6 (odds ratio, 2.58; 95% CI, 1.14-5.84; p = 0.02).

CONCLUSIONS

Higher soluble suppression of tumorigenicity-2 and interleukin-6 concentrations are each associated with worse outcomes during weaning of mechanical ventilation and increased need for reintubation in patients with acute respiratory distress syndrome. Biomarker-directed ventilator management may lead to improved outcomes in weaning of mechanical ventilation in patients with acute respiratory distress syndrome.

Mechanical Ventilator Discontinuation Process

The goal of this article is to discuss approaches to discontinuing invasive mechanical ventilation in a general intensive care unit (ICU) population. It considers approaches in which the clinician expects patient survival, as well as those that do not. Additionally, approaches to acute and chronic critical illness are included.

Micropatterned Endotracheal Tubes Reduce Secretion-Related Lumen Occlusion

Tracheal intubation disrupts physiological homeostasis of secretion production and clearance, resulting in secretion accumulation within endotracheal tubes (ETTs). Novel in vitro and in vivo models were developed to specifically recapitulate the clinical manifestations of ETT occlusion. The novel Sharklet™ micropatterned ETT was evaluated, using these models, for the ability to reduce the accumulation of both bacterial biofilm and airway mucus compared to a standard care ETT. Novel ETTs with micropattern on the inner and outer surfaces were placed adjacent to standard care ETTs in in vitro biofilm and airway patency (AP) models. The primary outcome for the biofilm model was to compare commercially-available ETTs (standard care and silver-coated) to micropatterned for quantity of biofilm accumulation. The AP model's primary outcome was to evaluate accumulation of artificial airway mucus. A 24-h ovine mechanical ventilation model evaluated the primary outcome of relative quantity of airway secretion accumulation in the ETTs tested. The secondary outcome was measuring the effect of secretion accumulation in the ETTs on airway resistance. Micropatterned ETTs significantly reduced biofilm by 71% (p = 0.016) compared to smooth ETTs. Moreover, micropatterned ETTs reduced lumen occlusion, in the AP model, as measured by cross-sectional area, in distal (85%, p = 0.005), middle (84%, p = 0.001) and proximal (81%, p = 0.002) sections compared to standard care ETTs. Micropatterned ETTs reduced the volume of secretion accumulation in a sheep model of occlusion by 61% (p < 0.001) after 24 h of mechanical ventilation. Importantly, micropatterned ETTs reduced the rise in ventilation peak inspiratory pressures over time by as much as 49% (p = 0.005) compared to standard care ETTs. Micropatterned ETTs, demonstrated here to reduce bacterial contamination and mucus occlusion, will have the capacity to limit complications occurring during mechanical ventilation and ultimately improve patient care.

The rapid shallow breathing index as a predictor of successful mechanical ventilation weaning: clinical utility when calculated from ventilator data

OBJECTIVE:

The use of the rapid shallow breathing index (RSBI) is recommended in ICUs, where it is used as a predictor of mechanical ventilation (MV) weaning success. The aim of this study was to compare the performance of the RSBI calculated by the traditional method (described in 1991) with that of the RSBI calculated directly from MV parameters.

METHODS:

This was a prospective observational study involving patients who had been on MV for more than 24 h and were candidates for weaning. The RSBI was obtained by the same examiner using the two different methods (employing a spirometer and the parameters from the ventilator display) at random. In comparing the values obtained with the two methods, we used the Mann-Whitney test, Pearson's linear correlation test, and Bland-Altman plots. The performance of the methods was compared by evaluation of the areas under the ROC curves.

RESULTS:

Of the 109 selected patients (60 males; mean age, 62 ± 20 years), 65 were successfully weaned, and 36 died. There were statistically significant differences between the two methods for respiratory rate, tidal volume, and RSBI (p < 0.001 for all). However, when the two methods were compared, the concordance and the intra-observer variation coefficient were 0.94 (0.92-0.96) and 11.16%, respectively. The area under the ROC curve was similar for both methods (0.81 ± 0.04 vs. 0.82 ± 0.04; p = 0.935), which is relevant in the context of this study.

CONCLUSIONS:

The satisfactory performance of the RSBI as a predictor of weaning success, regardless of the method employed, demonstrates the utility of the method using the mechanical ventilator.

Rapid shallow breathing index

Predicting successful liberation of patients from mechanical ventilation has been a focus of interest to clinicians practicing in intensive care. Various weaning indices have been investigated to identify an optimal weaning window. Among them, the rapid shallow breathing index (RSBI) has gained wide use due to its simple technique and avoidance of calculation of complex pulmonary mechanics. Since its first description, several modifications have been suggested, such as the serial measurements and the rate of change of RSBI, to further improve its predictive value. The objective of this paper is to review the utility of RSBI in predicting weaning success. In addition, the use of RSBI in specific patient populations and the reported modifications of RSBI technique that attempt to improve the utility of RSBI are also reviewed.

Predictors of extubation success in acute ischemic stroke patients

BACKGROUND

Acute ischemic stroke (AIS) patients often undergo intubation and mechanical ventilation (MV). Prolonged intubation and MV have disadvantages and complications. Conventional extubation criteria based only on respiratory parameters are insufficient to guide extubation practices in stroke patients where capacity for airway protection is a major concern.

OBJECTIVE

To identify clinical and neuroanatomical markers of successful extubation in AIS patients requiring MV.

METHODS

Retrospective review of tertiary care hospital patient database from May 2009-November 2012 to identify consecutive patients with AIS intubated during hospitalization. We assessed the effect of age, sex, baseline National Institutes of Health Stroke Scale (NIHSS) score, level of consciousness, facial weakness, dysarthria, neglect, infarct location, dysphagia, respiratory parameters and history of pneumonia on successful extubation by hospital discharge using multivariate logistic regression analysis.

RESULTS

112 subjects met study criteria and were included in the analysis. Age and NIHSS scores (mean±standard deviation) were 74.5±16.1years and 19±9.8, respectively; 56% were women. In multivariate analysis, NIHSS score≤15 (Odds Ratio 4.6, 95% Confidence Interval 1.9-11.3, p<0.001) and absence of dysarthria prior to intubation (Odds Ratio 3.0, 95% Confidence interval 1.1-8.3, p=0.04) were independently associated with successful extubation. Conventional respiratory parameters had no effect on extubation success in this cohort.

CONCLUSIONS

Milder stroke and absence of dysarthria prior to intubation were independently associated with extubation success. Our findings could help inform extubation practices in patients with AIS though prospective validation is necessary.

Reflex cough PEF as a predictor of successful extubation in neurological patients

Objective:

To evaluate the use of reflex cough PEF as a predictor of successful extubation in neurological patients who were candidates for weaning from mechanical ventilation.

Methods:

This was a cross-sectional study of 135 patients receiving mechanical ventilation for more than 24 h in the ICU of Cristo Redentor Hospital, in the city of Porto Alegre, Brazil. Reflex cough PEF, the rapid shallow breathing index, MIP, and MEP were measured, as were ventilatory, hemodynamic, and clinical parameters.

Results:

The mean age of the patients was 47.8 ± 17 years. The extubation failure rate was 33.3%. A reflex cough PEF of &lt; 80 L/min showed a relative risk of 3.6 (95% CI: 2.0-6.7), and the final Glasgow Coma Scale score showed a relative risk of 0.64 (95% CI: 0.51-0.83). For every 1-point increase in a Glasgow Coma Scale score of 8, there was a 36% reduction in the risk of extubation failure.

Conclusions:

Reflex cough PEF and the Glasgow Coma Scale score are independent predictors of extubation failure in neurological patients admitted to the ICU.

Discontinuation of ventilatory support: new solutions to old dilemmas

PURPOSE OF REVIEW

Weaning from mechanical ventilation implies two separate but closely related aspects of care, the discontinuation of mechanical ventilation and removal of artificial airway, which implies routine clinical dilemmas. Extubation delay and extubation failure are associated with poor clinical outcomes. We sought to summarize recent evidence on weaning.

RECENT FINDINGS

Tolerance to an unassisted breathing does not require routine use of weaning predictors and can be addressed using weaning protocols or by implementing automatic weaning methods. Spontaneous breathing trial can be performed on low levels of pressure support, continuous positive airway pressure, or T-piece. Echocardiographic tools may help to prevent the failure of extubation. Noninvasive ventilation can prevent respiratory failure after extubation, when used in hypercapnic patients. Recently, sedation protocols and early mobilization in ventilated critically ill patients may decrease weaning period and duration of mechanical ventilation, and prevent extubation failure and complications such as ICU-acquired weakness. New techniques have been performed to identify patients with high risk for extubation failure.

SUMMARY

There is an interesting body of clinical research in the discontinuation of mechanical ventilation. Recent randomized controlled studies provide high-level evidence for the best approaches to weaning, especially in patients who fail the first spontaneous breathing trial or targeted populations.

Weaning from mechanical ventilation: a cross-sectional study of reference values and the discriminative validity of aging

[Purpose] To evaluate pre-extubation variables and check the discriminative validity of age as well as its correlation with weaning failure in elderly patients. [Subjects and Methods] Two hundred thirty-nine consecutive patients (48% female) who were on mechanical ventilation and had undergone orotracheal intubation were divided into four subgroups according to their age: <59 years, 60-69 years, 70-79 years, and >80 years old. The expiratory volume (VE), respiratory frequency (f), tidal volume (VT), and respiratory frequency/tidal volume ratio (f/VT) were used to examine differences in weaning parameters between the four subgroups, and age was correlated with weaning failure. [Results] The rate of weaning failure was 27.8% in patients aged >80 years and 22.1% in patients aged <60 years old. Elderly patients presented higher f/VT and f values and lower VT values. The areas under the receiver operating characteristic curves for f/VT ratio were smaller than those published previously. [Conclusion] Our results indicate that aging influences weaning criteria without causing an increase in weaning failure.

Predictors of extubation failure in neurocritical patients identified by a systematic review and meta-analysis

Background

Prediction of extubation failure, particularly in neurocritical patients, is unique and controversial. We conducted a systematic review and meta-analysis to identify the risk factors for extubation failure in these patients.

Methods

A literature search of databases (MEDLINE, EMBASE, the Cochrane Library, and Web of Science) was performed up to August of 2013 to identify trials that evaluated extubation failure predictors. Included trials were either prospective or retrospective cohort studies.

Results

Nine studies involving 928 participants were included. The systematic review and meta-analysis revealed that the following were predictive for extubation failure: pneumonia, atelectasis, mechanical ventilation of >24 h, a low Glasgow Coma Scale score (7–9T) (OR = 4.96, 95% CI = 1.61–15.26, P = 0.005), the inability to follow commands (OR = 2.07, 95% CI = 1.15–3.71, P = 0.02), especially the command to close the eyes, thick secretion, and no intact gag reflex. Meanwhile, the following were not predictive for extubation failure: sex, secretion volume, coughing upon suctioning, and the inability to follow one command among showing two fingers, wiggling the toes, or coughing on command. Additionally, some traditional weaning parameters were shown to poorly predict extubation failure in neurocritical patients.

Conclusions

Besides pneumonia, atelectasis, and the duration of mechanical ventilation, other factors that should be taken into consideration in the prediction of extubation failure when neurocritical patients are weaned from tracheal intubation include neurologic abilities (Glasgow Coma Scale score and following commands), the secretion texture, and the presence of a gag reflex.

Application of heart-rate variability in patients undergoing weaning from mechanical ventilation

Introduction

The process of weaning may impose cardiopulmonary stress on ventilated patients. Heart-rate variability (HRV), a noninvasive tool to characterize autonomic function and cardiorespiratory interaction, may be a promising modality to assess patient capability during the weaning process. We aimed to evaluate the association between HRV change and weaning outcomes in critically ill patients.

Methods

This study included 101 consecutive patients recovering from acute respiratory failure. Frequency-domain analysis, including very low frequency, low frequency, high frequency, and total power of HRV was assessed during a 1-hour spontaneous breathing trial (SBT) through a T-piece and after extubation after successful SBT.

Results

Of 101 patients, 24 (24%) had SBT failure, and HRV analysis in these patients showed a significant decrease in total power (P = 0.003); 77 patients passed SBT and were extubated, but 13 (17%) of them required reintubation within 72 hours. In successfully extubated patients, very low frequency and total power from SBT to postextubation significantly increased (P = 0.003 and P = 0.004, respectively). Instead, patients with extubation failure were unable to increase HRV after extubation.

Conclusions

HRV responses differ between patients with different weaning outcomes. Measuring HRV change during the weaning process may help clinicians to predict weaning results and, in the end, to improve patient care and outcome.

Automatic Tube Compensation versus Pressure Support Ventilation and Extubation Outcome in Children: A Randomized Controlled Study

Background. Automatic tube compensation (ATC) has been developed to overcome the imposed work of breathing due to artificial airways during spontaneous breathing trials (SBTs). Objectives. This study aimed to assess extubation outcome after an SBT (spontaneous breathing trial) with ATC compared with pressure support ventilation (PSV) and to determine the risk factors for extubation failure. Methods. Patients ready for extubation were randomly assigned to two-hour spontaneous breathing trial with either ATC or pressure support ventilation. Results. In the ATC group (n = 17), 11 (65%) patients passed the SBT with subsequent extubation failure (9%). While in PSV group (n = 19), 10 (53%) patients passed the SBT with subsequent extubation failure (10%). This represented a positive predictive value for ATC of 91% and PSV of 90% (P = 0.52). Five (83%) of the patients who failed the SBT in ATC group were reintubated. This represented a higher negative predictive value for ATC of 83% than for PSV which was 56%. None of the assessed risk factors were independently associated with extubation failure including failed trial. Conclusion. ATC was equivalent to PSV in predicting patients with successful extubation. A trial failure in ATC group is associated with but does not definitely predict extubation failure.