Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the American College of Chest Physicians; the American Association for Respiratory Care; and the American College of Critical Care Medicine

Extubating the Neurocritical Care Patient: A Spontaneous Breathing Trial Algorithmic Approach

BACKGROUND

Delaying extubation in neurologically impaired patients otherwise ready for extubation is a source for significant morbidity, mortality, and costs. There is no consensus to suggest one spontaneous breathing trial (SBT) over another in predicting extubation success. We studied an algorithm using zero pressure support and zero positive end-expiratory pressure (ZEEP) SBT followed by 5-cm H₂O pressure support and 5-cm H₂O positive end-expiratory pressure (i.e., 5/5) SBT in those who failed ZEEP SBT.

METHODS

This is a retrospective analysis of intubated patients in a neurosciences intensive care unit. All eligible patients were initially challenged with ZEEP SBT. If failed, a 5/5 SBT was immediately performed. If passed either the ZEEP SBT or the subsequent 5/5 SBT, patients were liberated from mechanical ventilation.

RESULTS

In total, 108 adult patients were included. The majority of patients were successfully liberated from mechanical ventilation using ZEEP SBT alone (82.4%; p = 0.0007). Fifteen (13.8%) patients failed ZEEP SBT but immediately passed 5/5 SBT (p = 0.0005). One patient (0.93%) required reintubation. We found high sensitivity of this extubation algorithm (100; 95% CI 95.94-100%) but poor specificity (6.67; 95% CI 0.17-31.95%).

CONCLUSION

This study showed that the majority of patients could be successfully liberated from mechanical ventilation after a ZEEP SBT. In those who failed, a 5/5 SBT increased the successful liberation from mechanical ventilation.

[The obese patient and acute respiratory failure, a challenge for intensive care]

As a result of the constantly increasing epidemic of obesity, it has become a common problem in the intensive care unit. Morbid obesity has numerous consequences for the respiratory system. It affects both respiratory mechanics and pulmonary gas exchange, and dramatically impacts on the patient's management and outcome. With the potential for causing devastating respiratory complications, the particular anatomical and physiological characteristics of the respiratory system of the morbidly obese subject should be carefully taken into consideration. The present article reviews the management of obese patients in respiratory failure, from noninvasive ventilation to tracheostomy, including postural and technical issues, and explains the physiologically based ventilatory strategy both for NIV and invasive mechanical ventilation up to the weaning from the ventilatory support.

Noninvasive ventilation during weaning from prolonged mechanical ventilation

BACKGROUND AND OBJECTIVE

Non invasive ventilation (NIV) is currently employed for weaning from invasive ventilation (IMV) in the acute setting but its use for weaning from prolonged ventilation is still occasional and not standardized. We wanted to evaluate whether a combined protocol of NIV and decannulation in tracheostomized patients needing prolonged mechanical ventilation was feasible and what would be the one-year outcome.

METHODS

We studied patients still dependent from invasive mechanical ventilation with the following inclusion criteria: a) tolerance of at least 8h of unsupported breathing, b) progressive hypercapnia/acidosis after invasive ventilation discontinuation, c) good adaptation to NIV, d) favorable criteria for decannulation. These patients were switched from IMV to NIV and decannulated; then they were discharged on home NIV and followed-up for one year in order to evaluate survival and complications rate.

RESULTS

Data from patients consecutively admitted to a weaning unit were prospectively collected between 2005 and 2018. Out of 587 patients admitted over that period, 341 were liberated from prolonged mechanical ventilation. Fifty-one out of 147 unweaned patients (35%) were eligible for the protocol but only 46 were enrolled. After a mean length of stay of 35 days they were decannulated and discharged on domiciliary NIV. After one year, 38 patients were still alive (survival rate 82%) and 37 were using NIV with good adherence (only one patient was switched again to invasive ventilation).

CONCLUSIONS

NIV applied to patients with failed weaning from prolonged IMV is feasible and can facilitate the decannulation process. Patients successfully completing this process show good survival rates and few complications.

Variation in the practice of discontinuing mechanical ventilation in critically ill adults: study protocol for an international prospective observational study

INTRODUCTION

Research supports the use of specific strategies to discontinue mechanical ventilation (MV) in critically ill patients. Little is known about how clinicians actually wean and discontinue MV in practice or the association between different discontinuation strategies and outcomes. The primary objective of this study is to describe international practices in the use of (1) daily screening for readiness to discontinue MV, (2) modes of MV used before initial discontinuation attempts, (3) weaning and spontaneous breathing trial (SBT) protocols, (4) SBT techniques and (5) sedation and mobilisation practices to facilitate weaning and discontinuation. The secondary objectives are to identify patient characteristics and time-dependent factors associated with use of selected strategies, investigate associations between SBT outcome (failure vs success) and outcomes, explore differences between patients who undergo an SBT early versus later in their intensive care unit (ICU) stay, and investigate the associations between different SBT techniques and humidification strategies on outcomes.

METHODS AND ANALYSIS

We will conduct an international, prospective, observational study of MV discontinuation practices among critically ill adults who receive invasive MV for at least 24 hours at approximately 150 ICUs in six geographic regions (Canada, USA, UK, Europe, India and Australia/New Zealand). Research personnel at participating ICUs will collect demographic data, data to characterise the initial strategy or event that facilitated discontinuation of MV (direct extubation, direct tracheostomy, initial successful SBT, initial failed SBT or death before any attempt could be made), clinical outcomes and site information. We aim to collect data on at least 10 non-death discontinuation events in each ICU (at least 1500 non-death discontinuation events).

ETHICS AND DISSEMINATION

This study received Research Ethics Approval from St. Michael's Hospital (11-024) Research ethics approval will be sought from all participating sites. The results will be disseminated through publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03955874.

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.

Accuracy of chest auscultation in detecting abnormal respiratory mechanics in the immediate postoperative period after cardiac surgery

Objective:

To investigate the accuracy of chest auscultation in detecting abnormal respiratory mechanics.

Methods:

We evaluated 200 mechanically ventilated patients in the immediate postoperative period after cardiac surgery. We assessed respiratory system mechanics - static compliance of the respiratory system (C_st,rs) and respiratory system resistance (R,rs) - after which two independent examiners, blinded to the respiratory system mechanics data, performed chest auscultation.

Results:

Neither decreased/abolished breath sounds nor crackles were associated with decreased C_st,rs (≤ 60 mL/cmH₂O), regardless of the examiner. The overall accuracy of chest auscultation was 34.0% and 42.0% for examiners A and B, respectively. The sensitivity and specificity of chest auscultation for detecting decreased/abolished breath sounds or crackles were 25.1% and 68.3%, respectively, for examiner A, versus 36.4% and 63.4%, respectively, for examiner B. Based on the judgments made by examiner A, there was a weak association between increased R,rs (≥ 15 cmH₂O/L/s) and rhonchi or wheezing (ϕ = 0.31, p < 0.01). The overall accuracy for detecting rhonchi or wheezing was 89.5% and 85.0% for examiners A and B, respectively. The sensitivity and specificity for detecting rhonchi or wheezing were 30.0% and 96.1%, respectively, for examiner A, versus 10.0% and 93.3%, respectively, for examiner B.

Conclusions:

Chest auscultation does not appear to be an accurate diagnostic method for detecting abnormal respiratory mechanics in mechanically ventilated patients in the immediate postoperative period after cardiac surgery.

Influence of prolonged translaryngeal intubation on airway complications: a retrospective comparative analysis

PURPOSE

Tracheostomy is usually suggested to facilitate airway management of intensive care unit (ICU) patients requiring prolonged translaryngeal intubation (PTLI). While it is not uncommon for physicians to hesitate and delay to perform it for more than 2 weeks, clinically recognizable airway adverse effects following PTLI are rarely discussed. Therefore, we compared retrospectively the PTLI group with control to assess them in adult patients.

METHODS

During a period of 1991-2012, patients aged older than 15 years that were admitted to University of Tsukuba Hospital ICU, underwent translaryngeal intubation (TLI) for 14 days or longer, were retrospectively studied as Group P. Patients whose tracheas were intubated for 13 days or less were set up as a control group (Group C). Patients were excluded if they had undergone any procedures that might have affected recurrent laryngeal nerves.

RESULTS

Ninety-eight patients (M:F = 58:40) (group P) and 88 patients (M:F = 58:30) (group C) were included. There were no differences in patients' characteristics. Durations of TLI were 20.8 ± 6.8 days in group P and 3.8 ± 3.0 days in group C. There were no differences in the occurrence rates of severe airway adverse events. Although we found higher incidence rates of dysphagia and dysphonia/hoarseness in group P, the symptoms were mild and they were not prolonged. There were no differences in other signs and symptoms.

CONCLUSIONS

We found no difference in the occurrence rates of severe airway adverse events in both groups. Translaryngeal intubation may be tolerable in adults even if the duration exceeds 2 weeks.

Compare the effect of noninvasive ventilation and tracheotomy in critically ill mechanically ventilated neurosurgical patients: a retrospective observe cohort study

Objective

Patients with severe brain injury is usual at high risk of extubation failure, despite of those with no/minor primary respiratory problem, majority of them still needs long term respiratory support and has severe pulmonary complications. This retrospective study aimed to compare the effect of noninvasive ventilation (NIV) and tracheotomy on the prognosis in critically ill mechanically ventilated neurosurgical patients.

Methods

This is a single center, retrospective observe cohort study. Postoperative patients with brain injury consecutively admitted to ICU from November 1st, 2015 through February 28th, 2017, who had received invasive mechanical ventilation more than 48 h were screened, those who received NIV or tracheotomy procedure, meanwhile with Glasgow Coma Scale (GCS) score between 8 and 13 points before using NIV or undergoing tracheotomy, were retrospectively included in this study. The demographic data and clinical main outcomes such as ICU and hospital mortality, time of mechanical ventilation, length of ICU and hospital were collected. The primary outcome was the incidence of postoperative pulmonary infection between two groups.

Results

77 patients were included in this study. 33 patients received NIV, and 44 patients received tracheotomy through the ICU duration. The incidence of postoperative pulmonary infection in NIV group was significantly lower than that in tracheotomy group (54.5% VS 84.1%, P < 0.05), Application of NIV was associated with shorter duration of invasive mechanical ventilation ([median 123.0 h VS 195.0 h, P < 0.05). Moreover, GCS score at ICU discharge, as well as the difference of GCS score between at admission to ICU and ICU discharge were also better than the tracheotomy group (P < 0.001).

Conclusion

Compared with tracheotomy, use of NIV after extubation in critically ill mechanically ventilated neurosurgical patients may be associated with lower incidence of postoperative pulmonary infection, shorter duration of invasive mechanical ventilation and better improvement in brain function. Further studies need to verify the effect of NIV in this kind of patients.

Chest Ultrasound in Predication of Weaning Failure

AIM:

Failure of weaning from mechanical ventilation (MV) is a common problem that faces the intensivist despite having some prediction indices. Application of chest ultrasonography (US) may help in weaning and prediction of its outcome.

METHODS:

100 patients on invasive MV fulfilling criteria of weaning shifted to spontaneous breathing trial (SBT) (using PSV 8 cm H₂O) for 1 hour. Weaning failure was defined as; Failed SBT, reintubation and/or ventilation or death within 48 hours. Echocardiography was used to get Ejection fraction, E/A ratio, Doppler tissue imaging (DTI) &, lung ultrasound (LUS) was used to assess LUS score, diaphragm ultrasound was used to assess diaphragmatic thickening fraction (DTF).

RESULTS:

Mean age 57.1 ± 14.5, 62% were males. Weaning was successful in 80% of patients. LUS score was significantly higher in the failed weaning group: (10.8 ± 4.2) vs (16.5 ± 4.2 cm), (p: 0.001). (DTF) Was significantly higher in the successful weaning group: (43.0 ± 10.7) vs (28.9 ± 2.8 cm), (p: 0.001). DTF can predict successful weaning using Receiver operating characteristic (ROC) curves with the cutoff value: ≥ 29.5 with sensitivity 88.0% and specificity 80.0% with a p-value < 0.001.LUS score can predict weaning failure by using a ROC curve with cutoff value: ≥ 15.5 with sensitivity 70.0% and specificity 82.5 % with a p-value < 0.001.)

CONCLUSION:

The use of bedside chest US (to assess lung and diaphragm) of great benefit throughout the weaning process.

A rapid shallow breathing index threshold of 85 best predicts extubation success in chronic obstructive pulmonary disease patients with hypercapnic respiratory failure

Background

The rapid shallow breathing index (RSBI) is used clinically to help predict a patient's likelihood of successful liberation from mechanical ventilation (MV). However, the traditional threshold (<105 breaths/min/L) may underperform in patients with chronic obstructive pulmonary disease (COPD). We sought to determine the optimal RSBI threshold for COPD patients to improve the diagnostic accuracy for predicting successful ventilator liberation.

Methods

This was a prospective observational multicenter study of COPD patients [according to Global initiative for Chronic Obstructive Lung Disease (GOLD) criteria] admitted to the Medical ICUs of eight academic medical centers. All patients were intubated for hypercapnic respiratory failure and met the American Thoracic Society/European Respiratory Society guidelines to participate in a weaning trial. Ventilator weaning was conducted according to a defined protocol. RSBI was measured through the ventilator after 120 minutes of spontaneous breathing trial (SBT).

Results

Ninety patients were included (39 males and 51 females). Forty-three patients (48%) were successfully extubated whereas 47 patients (52%) failed extubation. Significant differences were observed between groups for duration-of-intubation [duration of intubation (DoI); P<0.0001], spontaneous tidal volume (VT) (P=0.03), and the ratio of dynamic-to-static compliance (P=0.005). The RSBI threshold of ≤85 breaths/min/L performed best: area under curve (AUC) receiver operating characteristic (ROC) curves 0.91, sensitivity 95.6%, specificity 90.4%, positive predictive value (PPV) 95.5%, and negative predictive value (NPV) 90.6%., positive likelihood ratio (LR+) 5.48, negative likelihood ratio (LR-) 0.25, and the diagnostic accuracy 91.7%. In post-ROC analyses, DoI and hospital length-of-stay (LOS) did not impact performance.

Conclusions

In COPD patients intubated with hypercapnia, RSBI ≤85 breaths/min/L outperformed the widely used threshold <105 breaths/min/L, yielding a 95.5% probability of extubation success, independent of ventilation duration or hospital LOS.

Long-Term Survival of Patients with Tracheostomy Having Different Diseases Followed up in the Respiratory Intensive Care Unit Outpatient Clinic: Which Patients are Lucky?

OBJECTIVES

Tracheostomy is a method of separating a patient from the mechanical ventilator in the intensive care unit (ICU). The long-term survivors among patients followed up with tracheostomy and ventilator in the respiratory ICU (RICU) outpatient clinic due to different diseases were investigated.

MATERIALS AND METHODS

This was a retrospectively designed cohort study between January 2004 and July 2018. Patients with chronic respiratory failure followed up with tracheostomy and/or ventilator at the RICU outpatient clinic were included in the study. Age, gender, indications and date of tracheostomy, use of domestic mechanical ventilation, and mortality were recorded. The groups were compared according to age, gender, and tracheostomy indication diseases, and the 1-3-year long-term mortality rates were analyzed by the Kaplan-Meier survival analysis, and the Cox regression test was performed.

RESULTS

A total of 134 (64% male) patients with a median age of 66 (54-73) years were included in the study. The indications for tracheostomy were heart failure (HF) and cerebrovascular diseases (38.1%), chronic obstructive pulmonary disease (COPD) (23.1%), neuromuscular diseases (22.4%), obesity hypoventilation (9.7%), and kyphoscoliosis (6.7%). Mortality was higher in patients >75 years old in the 3-year follow-up (p=0.022). The 3-year mortality hazard ratio (HR) factors and 95% confidence interval (CI) were as follows: age >75 years HR=1.71 (95% CI, 1.03-2.82; p<0.036) and HF and cerebrovascular disease diseases sequela HR=1.84 (95% CI, 1.03-3.29; p<0.041) significantly increased the 3-year mortality, and having COPD decreased mortality in 46% (p<0.041).

CONCLUSION

Patients with neuromuscular disorders, kyphoscoliosis, and COPD who have undergone tracheostomy were the luckiest group according to the 3-year survival rates, whereas patients with HF and cerebrovascular diseases were the unluckiest ones. The most important decision triangle is the patient's acceptance (A), family support (B), and tracheostomy indication (C), and this may vary from country to country depending on the beliefs of subjects.

The prognostic value of rapid shallow breathing index and physiologic dead space for weaning success in intensive care unit patients under mechanical ventilation

Background

Mechanical ventilation (MV) is a life-saving intervention that should be considered for patients with respiratory failure. This study was conducted to evaluate the predictive value of physiologic dead space for weaning success and compare it with rapid shallow breathing index (RSBI).

Materials and Methods

This cross-sectional study was conducted on 80 intensive care unit (ICU) patients who were under MV and candidate for weaning; among them, 68 patients experienced weaning success. RSBI was measured by dividing the respiratory rate by tidal volume. End-tidal CO₂ (PETCO₂) was obtained using caponometry, then dead-space was calculated as (VD/VT = (PaCO₂ - PETCO₂)/PaCO₂). PaCO₂ was also obtained from arterial blood gas recorded chart.

Results

Age, PaCO₂, PETCO₂, and RSBI were significantly different between those patients with and without weaning success (P < 0.05). RSBI ≤ 98 could predict the success of weaning with sensitivity 91.7%; specificity 76.5% and (AUC) area under the ROC curve (AUC = 0.87; 95% confidence interval [CI]: 0.78-0.94; P < 0.001). Dead space was not statistically significant prognostic index (AUC = 0.50; 95% CI: 0.31-0.69; P = 0.09).

Conclusion

In our study, RSBI was an effective predictive index for weaning success in ICU patients under MV, but dead space did not show significant predictive value. Further studies with larger sample sizes for providing more evidence are recommended.

Predictors of extubation readiness in preterm infants: a systematic review and meta-analysis

CONTEXT

A variety of extubation readiness tests have already been incorporated into clinical practice in preterm infants.

OBJECTIVE

To identify predictor tests of successful extubation and determine their accuracy compared with clinical judgement alone.

METHODS

MEDLINE, Embase, PubMed, Cochrane Library and Web of Science were searched between 1984 and June 2016. Studies evaluating predictors of extubation success during a period free of mechanical inflations in infants less than 37 weeks' gestation were included. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. After identifying and describing all predictor tests, pooled sensitivity and specificity estimates for the different test categories were generated using a bivariate random-effects model.

RESULTS

Thirty-five studies were included, showing wide heterogeneities in population characteristics, methodologies and definitions of extubation success. Assessments ranged from a few seconds to 24 hours, provided 0-6 cmH₂O positive end-expiratory pressure and measured several clinical and/or physiological parameters. Thirty-one predictor tests were identified, showing good sensitivities but low and variable specificities. Given the high variation in test definitions across studies, pooling could only be performed on a subset. The commonly performed spontaneous breathing trials had pooled sensitivity of 95% (95% CI 87% to 99%) and specificity of 62% (95% CI 38% to 82%), while composite tests offered the best performance characteristics.

CONCLUSIONS

There is a lack of strong evidence to support the use of extubation readiness tests in preterm infants. Although spontaneous breathing trials are attractive assessment tools, higher quality studies are needed for determining the optimal strategies for improving their accuracy.

Limiting ventilator-associated complications in ICU intubated subjects: strategies to prevent ventilator-associated events and improve outcomes

Introduction: Intubation is required to maintain the airways in comatose patients and enhance oxygenation in hypoxemic or ventilation in hypercapnic subjects. Recently, the Centers of Disease Control (CDC) created new surveillance definitions designed to identify complications associated with poor outcomes. Areas covered: The new framework proposed by CDC, Ventilator-Associated Events (VAE), has a range of definitions encompassing Ventilator-Associated Conditions (VAC), Infection-related Ventilator-Associated Complications (IVAC), or Possible Ventilator-Associated Pneumonia - suggesting replacing the traditional definitions of Ventilator-Associated Tracheobronchitis (VAT) and Ventilator-Associated Pneumonia (VAP). They focused more on oxygenation variations than on Chest-X rays or inflammatory biomarkers. This article will review the spectrum of infectious (VAP & VAT) complications, as well as the main non-infectious complications, namely pulmonary edema, acute respiratory distress syndrome (ARDS) and atelectasis. Strategies to limit these complications and improve outcomes will be presented. Expert commentary: Improving outcomes should be the objective of implementing bundles of prevention, based on risk factors amenable of intervention. Promotion of measures that reduce the exposition or duration of intubation should be a priority.

Automation of Mechanical Ventilation

Closed loop control of mechanical ventilation is routine and operates behind the ventilator interface. Reducing caregiver interactions is neither an advantage for the patient or the staff. Automated systems causing lack of situational awareness of the intensive care unit are a concern. Along with autonomous systems must come monitoring and displays that display patients' current condition and response to therapy. Alert notifications for sudden escalation of therapy are required to ensure patient safety. Automated ventilation is useful in remote settings in the absence of experts. Whether automated ventilation will be accepted in large academic medical centers remains to be seen.

Weaning from Mechanical Ventilation in ARDS: Aspects to Think about for Better Understanding, Evaluation, and Management

Acute respiratory distress syndrome (ARDS) is characterized by severe inflammatory response and hypoxemia. The use of mechanical ventilation (MV) for correction of gas exchange can cause worsening of this inflammatory response, called “ventilator-induced lung injury” (VILI). The process of withdrawing mechanical ventilation, referred to as weaning from MV, may cause worsening of lung injury by spontaneous ventilation. Currently, there are few specific studies in patients with ARDS. Herein, we reviewed the main aspects of spontaneous ventilation and also discussed potential methods to predict the failure of weaning in this patient category. We also reviewed new treatments (modes of mechanical ventilation, neuromuscular blocker use, and extracorporeal membrane oxygenation) that could be considered in weaning ARDS patients from MV.

The basics of respiratory mechanics: ventilator-derived parameters

Mechanical ventilation is a life-support system used to maintain adequate lung function in patients who are critically ill or undergoing general anesthesia. The benefits and harms of mechanical ventilation depend not only on the operator's setting of the machine (input), but also on their interpretation of ventilator-derived parameters (outputs), which should guide ventilator strategies. Once the inputs-tidal volume (V_T), positive end-expiratory pressure (PEEP), respiratory rate (RR), and inspiratory airflow (V')-have been adjusted, the following outputs should be measured: intrinsic PEEP, peak (Ppeak) and plateau (Pplat) pressures, driving pressure (ΔP), transpulmonary pressure (P_L), mechanical energy, mechanical power, and intensity. During assisted mechanical ventilation, in addition to these parameters, the pressure generated 100 ms after onset of inspiratory effort (P_0.1) and the pressure-time product per minute (PTP/min) should also be evaluated. The aforementioned parameters should be seen as a set of outputs, all of which need to be strictly monitored at bedside in order to develop a personalized, case-by-case approach to mechanical ventilation. Additionally, more clinical research to evaluate the safe thresholds of each parameter in injured and uninjured lungs is required.

Clinical differences between pulmonary and extrapulmonary acute respiratory distress syndrome: a retrospective cohort study of prospectively collected data in Japan

Background

Although acute respiratory distress syndrome (ARDS) reportedly shows various clinical phenotypes with different risk and prognostic factors, few studies have assessed the clinical features and prognosis of pulmonary and extrapulmonary ARDS. The aim of the present study was to investigate clinical differences between pulmonary and extrapulmonary ARDS.

Methods

In total, 200 patients who met the Berlin criteria and were diagnosed with ARDS between October 2004 and September 2017 were included. We classified the patients into pulmonary and extrapulmonary ARDS groups. Both groups were assessed for 60-day mortality, duration of ventilation, and other clinical features.

Results

There were 150 and 50 patients in the pulmonary and extrapulmonary ARDS groups, respectively. The two groups showed no significant differences in any assessment parameters except the serum lactate dehydrogenase (LDH) level, which was higher in the extrapulmonary ARDS group (P=0.01). After adjustment for potentially confounding covariates, there were no significant differences in 60-day mortality (P=0.99) and the duration of ventilation (P=0.45) between the two groups. Mortality was significantly associated with the disseminated intravascular coagulation (DIC) score, high-resolution computed tomography (HRCT) score, and serum LDH level in the pulmonary ARDS group and the DIC score and HRCT score in the extrapulmonary ARDS group.

Conclusions

Pulmonary and extrapulmonary ARDS may be comparable in terms of the prognosis and duration of ventilation. DIC and HRCT scores may be common clinical predictors of mortality with ARDS.

Obesity and Weaning from Mechanical Ventilation-An Exploratory Study

Introduction

Obesity is associated with increased risk of hypercapnic respiratory failure, prolonged duration on mechanical ventilation, and extended weaning periods.

Objective

Pilot study to determine whether morbidly obese adult tracheotomized subjects (body mass index [BMI] ⩾ 40) can be more efficiently weaned from the ventilator by optimizing their positive end-expiratory pressure (PEEP) using either an esophageal balloon or the best achieved static effective compliance.

Methods

We randomly assigned 25 morbidly obese adult tracheotomized subjects (median [interquartile range] BMI 53.4 [26.4]; range 40.4-113.8) to 1 of 2 methods of setting PEEP; using either titration guided by esophageal balloon to overcome negative transpulmonary pressure (Ptp) (goal Ptp 0-5 cmH₂O) (ESO group) or titration to maximize static effective lung compliance (Cstat group). Our outcomes of interest were number of subjects weaned by day 30 and time to wean.

Results

At day 30, there was no significant difference in percentage of subjects weaned. 8/13 subjects (62%) in the ESO Group were weaned vs. 9/12(75%) in the Cstat Group (P = 0.67). Among the 17 subjects who weaned, median time to ventilator liberation was significantly shorter in the ESO group: 3.5 days vs Cstat group 14 days (P = .01). Optimal PEEP in the ESO and Cstat groups was similar (ESO mean ± SD = 26.5 ± 5.7 cmH₂O and Cstat 24.2 ± 7 cmH₂O (P = .38).

Conclusions

Optimization of PEEP using esophageal balloon to achieve positive transpulmonary pressure did not change the proportion of patients weaned. Among patients who weaned, use of the esophageal balloon resulted in faster liberation from mechanical ventilation. There were no adverse consequences of the high PEEP (mean 25.4; range 13-37 cmH₂O) used in our study. The study was approved by the Institutional Review Board at our institution (UMCIRB#10-0343) and registered with clinicaltrials.gov (NCT02323009).

Neutrophil/lymphocyte ratio is helpful for predicting weaning failure: a prospective, observational cohort study

Background

To assess the usefulness of the neutrophil/lymphocyte ratio (NLR), a marker of inflammation and/or stress, for predicting weaning failure in patients receiving invasive mechanical ventilation (IMV), compared to levels of leukocytes and C-reactive protein (CRP).

Methods

This observational prospective cohort study was conducted from July 2013 to December 2016 in an intensive care unit in China, enrolling 269 consecutive patients receiving IMV. Patients underwent a spontaneous breathing trial (SBT) if they were ready to wean, and underwent extubation if they passed the SBT. The evaluated markers were measured immediately prior to SBT, and compared between weaning-failure and weaning-success patients. Receiver-operating characteristic (ROC) curve and logistic regression analyses were used to evaluate the ability of these markers to predict weaning failure.

Results

In all, 94 (34.9%) patients failed the weaning process (66 failed SBT and 28 presented with post-extubation respiratory distress). NLR was a better predictor of failure (area under the ROC curve, 0.69; 95% CI, 0.62-0.76) than leukocyte levels (0.60, 0.53-0.67) and CRP values (0.58, 0.51-0.65). NLR >11, leukocyte counts >10.5×10⁹/L, and CRP >58 mg/L prior to weaning had the best combination of sensitivity (73%, 64%, and 63%, respectively), specificity (59%, 55%, and 63%), positive predictive value (49%, 43%, and 48%), negative predictive value (81%, 74%, and 76%), and diagnostic accuracy (64%, 58%, and 63%) for predicting weaning failure. However, only NLR >11 (odds ratio, 5.91; 95% CI, 3.08-11.33; P<0.001) was an independent predictor of weaning failure in the adjusted logistic regression model.

Conclusions

NLR may be a useful marker for predicting weaning failure, and weaning at NLR >11 might be considered with caution. Further study with a larger sample size and with weaning outcome as a variable of concern is warranted. Trial registration: ClinicalTrials.gov identifier: NCT02981589.

Unplanned postoperative reintubation following general and vascular surgical procedures: Outcomes and risk factors

Background

Unplanned postoperative reintubation (UPR) is a marker for severe adverse outcomes following general and vascular surgery.

Study design

A retrospective analysis of 8809 adult patients, aged 18 years and older, who underwent major general and vascular surgery at a large single-center urban hospital was conducted from January 2013 to September 2016. Patients were grouped into those who experienced UPR and those who did not. Univariate and multivariate regression analyses were used to identify predictors of UPR, and association of UPR with adverse postoperative outcomes. All regression models had Hosmer-Lemeshow P > 0.05, and C-statistic >0.75, indicating excellent goodness-of-fit and discrimination.

Results

Of the 8809 patients included, 138 (1.6%) experienced UPR. There was no statistical difference in incidence of UPR between general and vascular surgery patients (p = 0.53). Independent predictors of UPR advanced age (OR 5.1, 95%CI 3.5–7.5, p < 0.01), higher ASA status (OR 7.9, 95%CI 5.6–11.1, p < 0.01), CHF (OR 7.0, 95%CI 3.6–13.9, p = 0.02), acute renal failure or dialysis (OR 3.1, 95%CI 1.8–5.7, p = 0.01), weight loss (OR 5.2, 95%CI 2.8–9.6, p = 0.01), systemic sepsis (OR 4.8, 95%CI 3.4–6.9, p < 0.01), elevated preoperative creatinine (OR 4.2, 95%CI 3.0–5.9, p = 0.01), hypoalbuminemia (OR 5.3, 95% CI 3.8–7.5, p = 0.01), and anemia (OR 4.0, 95%CI 2.8–5.9, p < 0.01). Following surgery, UPR was associated with increased mortality (OR 3.8, 95%CI 2.7–5.2, p < 0.01), pulmonary complications (OR 1.8, 95%CI 1.7–2.0, p < 0.01), renal complications (OR 2.6, 95%CI 1.7–3.5, p < 0.01), cardiac complications (OR 4.6, 95%CI 2.0–6.7, p < 0.01), postoperative RBC transfusion (OR 5.7, 95%CI 3.8–8.6,p < 0.01), and prolonged hospitalization (OR 1.8, 95%CI 1.5–2.4, p < 0.01).

Conclusion

UPR is significantly associated with postoperative morbidity and mortality. Perioperative management aimed at decreasing incidences of UPR after noncardiac surgery should target preoperative anemia in addition to previously identified predictors.

•

Unplanned postoperative reintubation (UPR) is a marker for severe adverse outcome following surgery.

•

UPR following major surgery occurred in 1.6% patients.

•

Patients who required UPR had increased mortality.

•

Underlying risk factors and postoperative complications may be a marker for other severe systemic disease.

Timing of Tracheostomy in Intensive Care Unit Patients

Introduction  The ideal timing of tracheostomy in intensive care units (ICUs) for critically ill patients undergoing prolonged mechanical ventilation (MV) is still a controversial issue.

Objectives  To determine the proper timing of tracheostomy and its impact on various clinical outcomes of adult patients in ICUs undergoing prolonged MV.

Methods  The present study consisted of a sample of 67 ICU adult patients who were submitted to open surgical tracheostomy and divided into two groups: 30 patients in the early tracheostomy (ET) group (within 1–10 days post intubation), and 37 patients in the late tracheostomy (LT) group (within 11–21 days post intubation). The correlation between the timing of tracheostomy of each group and various associated ICU clinical parameters were analyzed.

Results  The sample consisted of 61.19% male and 38.81% female patients, with a mean age of 47.263 ± 7.581 years. The mean MV duration in days was 7.91 ± 4.937 standard deviation (SD) in the ET group, and 15.32 ± 7.472 SD in the LT group ( p  = 0.001), with a mean sedation time of 6.13 ± 4.647 SD in the ET group, and of 11.98 ± 6.596 SD in the LT group ( p  = 0.001). The duration of the weaning process duration had a mean of 2.75 ± 2.586 SD days in the ET group, and of 5.39 ± 5.817 SD days in the LT group ( p  = 0.025), with a weaning failure rate of 28.57% in the ET group and 71.42% in the LT group ( p  = 0.01). The Mean ICU stay was 26.18 ± 4.732 SD in the ET group, and 11.98 ± 6.596 SD in the LT group ( p  = 0.879), and the incidence of ventilator-associated pneumonia (VAP) of 23.33% in the ET group and of 27.02% in the LT group ( p  = 0.15).

Conclusion  Early tracheostomy had a notable benefit in shortening the duration of the MV, lessening the sedation time and minimizing the risks of weaning failure, but it had no significant impact on both the overall duration of ICU stay and VAP incidence.

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

Background

Extubation failure is associated with mortality and morbidity in the intensive care unit. Ventilator weaning protocols have been introduced, and extubation is conducted based on the results of a spontaneous breathing trial. Room for improvement still exists in extubation management, and additional objective indices may improve the safety of the weaning and extubation process. Static lung-thorax compliance reflects lung expansion difficulty that is caused by several conditions, such as atelectasis, fibrosis, and pleural effusion. Nevertheless, it is not used commonly in the weaning and extubation process. In this study, we investigated whether lung-thorax compliance is a good index of extubation failure in adults even when patients pass a spontaneous breathing trial.

Methods

In a single-center, retrospective cohort study, patients over 18 years of age were mechanically ventilated, weaned with proportional assist ventilation, and underwent a spontaneous breathing trial process in surgical intensive care units of Kagawa University Hospital from July 2014 to June 2016. Extubation failure was the outcome measure of the study. We defined extubation failures as when patients were reintubated or underwent non-invasive positive-pressure ventilation within 24 h after extubation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the clinical involvement of several parameters. The area under the curve (AUC) was calculated to assess the discriminative power of the parameters.

Results

We analyzed 173 patients and compared the success and failure groups. Most patients (162, 93.6%) were extubated successfully, and extubation failed in 11 patients (6.4%). The averages of lung-thorax compliance values in the success and failure groups were 71.9 ± 23.0 and 43.3 ± 14.6 mL/cmH₂O, respectively, and were significantly different (p < 0.0001). In the ROC curve analysis, the AUC was highest for lung-thorax compliance (0.862), followed by the respiratory rate (0.821), rapid shallow breathing index (0.781), Acute Physiology and Chronic Health Evaluation II score (0.72), heart rate (0.715), and tidal volume (0.695).

Conclusions

Lung-thorax compliance measured during a spontaneous breathing trial is a potential indicator of extubation failure in postoperative patients.

Noninvasive ventilation in acute respiratory failure: which recipe for success?

Noninvasive positive-pressure ventilation (NPPV) to treat acute respiratory failure has expanded tremendously over the world in terms of the spectrum of diseases that can be successfully managed, the locations of its application and achievable goals.

The turning point for the successful expansion of NPPV is its ability to achieve the same physiological effects as invasive mechanical ventilation with the avoidance of the life-threatening risks correlated with the use of an artificial airway.

Cardiorespiratory arrest, extreme psychomotor agitation, severe haemodynamic instability, nonhypercapnic coma and multiple organ failure are absolute contraindications for NPPV. Moreover, pitfalls of NPPV reduce its rate of success; consistently, a clear plan of what to do in case of NPPV failure should be considered, especially for patients managed in unprotected setting. NPPV failure is likely to be reduced by the application of integrated therapeutic tools in selected patients handled by expert teams.

In conclusion, NPPV has to be considered as a rational art and not just as an application of science, which requires the ability of clinicians to both choose case-by-case the best “ingredients” for a “successful recipe” (i.e.patient selection, interface, ventilator, interface,etc.) and to avoid a delayed intubation if the ventilation attempt fails.

Diaphragmatic ultrasonography for predicting ventilator weaning: A meta-analysis

BACKGROUND

Weaning failure is common in mechanically ventilated patients. Whether ultrasound can predict weaning outcome remains controversial. This meta-analysis was performed to assess the accuracy of diaphragmatic ultrasonography for predicting reintubation within 48 hours of extubation.

METHODS

Literature search was performed in PubMed, Embase, and Cochrane Library to identify all the relevant papers, published in English up to July 16, 2017. Eligible studies were included if data were in adequate details to rebuild 2 × 2 contingency tables. Methodological quality of the included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) in Review Manager 5.3. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curve were pooled using the fixed or random effects model, meanwhile, the heterogeneity was evaluated using Cochran Q test and I statistics in Meta-DiSc 1.4. Publication bias was assessed using Deeks funnel plot in Stata 12.0.

RESULTS

Thirteen studies with 742 subjects were included in this meta-analysis. The pooled sensitivities for diaphragm excursion (DE) and diaphragm thickness fraction (DTF) were 0.786 and 0.893, and the pooled specificities were 0.711 and 0.796, respectively. The area under curve (AUC) for DE and DTF were 0.8590 and 0.8381. The DORs for DE and DTF were 10.623 and 32.521. No publication bias was observed among these studies.

CONCLUSIONS

Diaphragmatic ultrasonography is a promising tool for predicting reintubation within 48 hours of extubation. However, due to heterogeneities among the included studies, large-scale studies are warranted to confirm our findings.

Effect of early tracheostomy on clinical outcomes in critically ill lung transplant recipients

OBJECTIVES

The purpose of this study was to evaluate the effect of early tracheostomy in patients following lung transplantation and to determine its optimal timing and influence on clinical outcomes.

METHODS

We retrospectively reviewed records of 96 adult patients who underwent lung transplantation at our institution between August 2008 and January 2016. Time-to-tracheostomy was defined based on timing of the procedure: "early" if less than 3 days or "late" if 3 or more days after lung transplantation.

RESULTS

Forty-nine patients (51%) underwent tracheostomy 3.2 ± 1.8 days after lung transplantation. Among these patients, 21 patients (42.9%) underwent early tracheostomy and 28 patients (57.1%) underwent late tracheostomy. Multivariable logistic regression analysis indicated that preoperative performance status was a significant predictor for tracheostomy (p = 0.006, odds ratio 2.72). Patients in the early tracheostomy group began walking (p = 0.003) and oral feeding (p = 0.0006) earlier and had a shorter duration of mechanical ventilation (p = 0.04) and shorter length of intensive care unit (p = 0.01) and hospital stay (p = 0.04) than patients in the late tracheostomy group. No significant differences in postoperative walking (p = 0.06), oral feeding (p = 0.17), or length of hospital stay (p = 0.37) were observed between patients who underwent early tracheostomy and those who did not undergo tracheostomy.

CONCLUSIONS

Early tracheostomy following lung transplantation decreased both intensive care and hospital stay, due to improved postoperative recovery, even in patients with poor preoperative conditions. Furthermore, length of hospital stay in patients with early tracheostomy was similar to that of patients without tracheostomy after lung transplantation.

Central Venous Oxygen Saturation as a Predictor of a Successful Spontaneous Breathing Trial from Mechanical Ventilation: A Prospective, Nested Case-Control Study

Background:

Weaning from mechanical ventilation is a key element in the care of critically ill patients, and Spontaneous Breathing Trial (SBT) is a crucial step in this procedure. This nested case-control study aimed to evaluate whether central oxygen saturation (ScvO₂) values and their changes could independently predict the SBT outcome among mechanically ventilated patients.

Methods:

A prospective cohort of patients who were mechanically ventilated for at least 48hours and fulfilled the criteria of readiness to wean constituted the study population. All patients attempted a SBT and were then categorized in SBT success group and SBT failure group, based on a combination of criteria which indicated whether SBT was successful or not. Multivariate binary logistic regression analysis was utilized to indicate the independent predictors of SBT success, while the Receiver Operating Characteristic (ROC) curves were used to demonstrate the diagnostic accuracy of these independent predictors.

Results:

Seventy-seven patients 69(18-86) years old; 62.3% male) constituted the study population. SBT was successful among 63.6% of them. A decrease in ScvO₂ values (ΔScvO₂) < 4% between the beginning and the end of the trial independently predicted the successful outcome (OR=18.278; 95% CI=4.017-83.163), along with age, Hemoglobin concentration (Hb) and arterial oxygen saturation (SaO₂). Diagnostic accuracy for ΔScvO₂ alone (ROC area=0.715) was slightly superior to that of either SaO₂ (0.625) or Hb (0.685) to predict SBT success.

Conclusion:

ScvO₂ is an independent predictor of the weaning outcome and its evaluation may further facilitate the accurate categorization among those patients who pass or fail the SBT.

[Prolonged weaning during early neurological and neurosurgical rehabilitation : S2k guideline published by the Weaning Committee of the German Neurorehabilitation Society (DGNR)]

Prolonged weaning of patients with neurological or neurosurgery disorders is associated with specific characteristics, which are taken into account by the German Society for Neurorehabilitation (DGNR) in its own guideline. The current S2k guideline of the German Society for Pneumology and Respiratory Medicine is referred to explicitly with regard to definitions (e.g., weaning and weaning failure), weaning categories, pathophysiology of weaning failure, and general weaning strategies. In early neurological and neurosurgery rehabilitation, patients with central of respiratory regulation disturbances (e.g., cerebral stem lesions), swallowing disturbances (neurogenic dysphagia), neuromuscular problems (e.g., critical illness polyneuropathy, Guillain-Barre syndrome, paraplegia, Myasthenia gravis) and/or cognitive disturbances (e.g., disturbed consciousness and vigilance disorders, severe communication disorders), whose care during the weaning of ventilation requires, in addition to intensive medical competence, neurological or neurosurgical and neurorehabilitation expertise. In Germany, this competence is present in centers of early neurological and neurosurgery rehabilitation, as a hospital treatment. The guideline is based on a systematic search of guideline databases and MEDLINE. Consensus was established by means of a nominal group process and Delphi procedure moderated by the Association of the Scientific Medical Societies in Germany (AWMF). In the present guideline of the DGNR, the special structural and substantive characteristics of early neurological and neurosurgery rehabilitation and existing studies on weaning in early rehabilitation facilities are examined.Addressees of the guideline are neurologists, neurosurgeons, anesthesiologists, palliative physicians, speech therapists, intensive care staff, ergotherapists, physiotherapists, and neuropsychologists. In addition, this guideline is intended to provide information to specialists for physical medicine and rehabilitation (PMR), pneumologists, internists, respiratory therapists, the German Medical Service of Health Insurance Funds (MDK) and the German Association of Health Insurance Funds (MDS). The main goal of this guideline is to convey the current knowledge on the subject of "Prolonged weaning in early neurological and neurosurgery rehabilitation".

Management of Pulmonary Failure after Burn Injury: From VDR to ECMO

This article highlights the challenges in managing pulmonary failure after burn injury. The authors review several different ventilator techniques, provide weaning parameters, and discuss complications.

Neurological Critical Care Services’ Influence Following Large Hemispheric Infarction and Their Impact on Resource Utilization

Introduction: Acute ischemic stroke (AIS) is the fourth leading cause of death in the US. Numerous studies have demonstrated the use of comprehensive stroke units and neurological intensive care units (NICU) in improving outcomes after stroke. We hypothesized that an expanded neurocritical care (NCC) service would decrease resource utilization in patients with LHI.

Methods: Retrospective data from consecutive admissions of large hemispheric infarction (LHI) patients requiring mechanical ventilation were acquired from the hospital medical records. Between 2011-2013, there were 187 consecutive patients admitted to the Jefferson Hospital for Neuroscience (Philadelphia, USA) with AIS and acute respiratory failure. Our intention was to determine the number of tracheostomies done over time. The primary outcome measure was the number of tracheostomies over time. Secondary outcomes were, ventilator-free days (Vfd), total hospital charges, intensive care unit length of stay (ICU-LOS), and total hospital length of stay (hospital-LOS), including ICU LOS. Hospital charges were log-transformed to meet assumptions of normality and homoscedasticity of residual variance terms. Generalized Linear Models were used and ORs and 95% CIs calculated. The significance level was set at α = 0.05.

Results: Of the 73 patients included in this analysis, 33% required a tracheostomy. There was a decrease in the number of tracheostomies undertaken since 2011. (OR 0.8; 95% CI 0.6-0.9: p=0.02).

Lower Vfd were seen in tracheostomized patients (OR 0.11; 95%CI 0.1-0.26: p<0.0001). The log-hospital charges decreased over time but not significantly (OR 0.9; 95%CI 0.78-1.07: p=0.2) and (OR 0.99; 95%CI 0.85-1.16: p=0.8) from 2012 to 2013 respectively.

The ICU-LOS at 23 days vs 10 days (p=0.01) and hospital-LOS at 33 days vs 11 days (p=0.008) were higher in tracheostomized patients.

Conclusion: The data suggest that in LHI-patients requiring mechanical ventilation, a dedicated NCC service reduces the overall need for tracheostomy, increases Vfd, and decreases ICU and hospital-LOS.

Design of a new artificial breathing system for simulating the human respiratory activities

The purpose of this work is the conception and implementation of an artificial active respiratory system that allows the simulation of human respiratory activities. The system consists of two modules, mechanical and electronical. The first one represents a cylindrical lung adjustable in resistance and compliance. This lung is located inside a transparent thoracic box, connected to a piston that generates variable respiratory efforts. The parameters of the system, which are pressure, flow and volume, are measured by the second module. A computer application was developed to control the whole system, and enables the display of the parameters. A series of tests were made to evaluate the respiratory efforts, resistances and compliances. The results were compared to the bibliographical studies, allowing the validation of the proposed system.

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.

Usefulness of radiological signs of pulmonary congestion in predicting failed spontaneous breathing trials

Objective:

Inspiratory fall in intrathoracic pressure during a spontaneous breathing trial (SBT) may precipitate cardiac dysfunction and acute pulmonary edema. We aimed to determine the relationship between radiological signs of pulmonary congestion prior to an SBT and weaning outcomes.

Methods:

This was a post hoc analysis of a prospective cohort study involving patients in an adult medical-surgical ICU. All enrolled individuals met the eligibility criteria for liberation from mechanical ventilation. Tracheostomized subjects were excluded. The primary endpoint was SBT failure, defined as the inability to tolerate a T-piece trial for 30-120 min. An attending radiologist applied a radiological score on interpretation of digital chest X-rays performed before the SBT.

Results:

A total of 170 T-piece trials were carried out; SBT failure occurred in 28 trials (16.4%), and 133 subjects (78.3%) were extubated at first attempt. Radiological scores were similar between SBT-failure and SBT-success groups (median [interquartile range] = 3 [2-4] points vs. 3 [2-4] points; p = 0.15), which, according to the score criteria, represented interstitial lung congestion. The analysis of ROC curves demonstrated poor accuracy (area under the curve = 0.58) of chest x-rays findings of congestion prior to the SBT for discriminating between SBT failure and SBT success. No correlation was found between fluid balance in the 48 h preceding the SBT and radiological score results (ρ = −0.13).

Conclusions:

Radiological findings of pulmonary congestion should not delay SBT indication, given that they did not predict weaning failure in the medical-surgical critically ill population.

(ClinicalTrials.gov identifier: NCT02022839 [http://www.clinicaltrials.gov/])

Neurological Critical Care Services' Influence Following Large Hemispheric Infarction and Their Impact on Resource Utilization

INTRODUCTION

Acute ischemic stroke (AIS) is the fourth leading cause of death in the US. Numerous studies have demonstrated the use of comprehensive stroke units and neurological intensive care units (NICU) in improving outcomes after stroke. We hypothesized that an expanded neurocritical care (NCC) service would decrease resource utilization in patients with LHI.

METHODS

Retrospective data from consecutive admissions of large hemispheric infarction (LHI) patients requiring mechanical ventilation were acquired from the hospital medical records. Between 2011-2013, there were 187 consecutive patients admitted to the Jefferson Hospital for Neuroscience (Philadelphia, USA) with AIS and acute respiratory failure. Our intention was to determine the number of tracheostomies done over time. The primary outcome measure was the number of tracheostomies over time. Secondary outcomes were, ventilator-free days (Vfd), total hospital charges, intensive care unit length of stay (ICU-LOS), and total hospital length of stay (hospital-LOS), including ICU LOS. Hospital charges were log-transformed to meet assumptions of normality and homoscedasticity of residual variance terms. Generalized Linear Models were used and ORs and 95% CIs calculated. The significance level was set at α = 0.05.

RESULTS

Of the 73 patients included in this analysis, 33% required a tracheostomy. There was a decrease in the number of tracheostomies undertaken since 2011. (OR 0.8; 95% CI 0.6-0.9: p=0.02).Lower Vfd were seen in tracheostomized patients (OR 0.11; 95%CI 0.1-0.26: p<0.0001). The log-hospital charges decreased over time but not significantly (OR 0.9; 95%CI 0.78-1.07: p=0.2) and (OR 0.99; 95%CI 0.85-1.16: p=0.8) from 2012 to 2013 respectively.The ICU-LOS at 23 days vs 10 days (p=0.01) and hospital-LOS at 33 days vs 11 days (p=0.008) were higher in tracheostomized patients.

CONCLUSION

The data suggest that in LHI-patients requiring mechanical ventilation, a dedicated NCC service reduces the overall need for tracheostomy, increases Vfd, and decreases ICU and hospital-LOS.

Stakeholder Engagement in Trial Design: Survey of Visitors to Critically Ill Patients Regarding Preferences for Outcomes and Treatment Options during Weaning from Mechanical Ventilation

RATIONALE

Stakeholder engagement in research is expected to provide unique insights, make research investments more accountable and transparent, and ensure that future research is applicable to patients and family members.

OBJECTIVES

To inform the design of a trial of strategies for weaning from mechanical ventilation, we sought to identify preferences of patient visitors regarding outcome and treatment measures.

METHODS

We conducted an interviewer-administered questionnaire of visitors of critically ill patients in two family waiting rooms serving three intensive care units (ICUs) in Toronto, Canada. Respondents rated the importance of general and ventilation-related outcomes in two hypothetical scenarios (before a first spontaneous breathing trial, and after a failed spontaneous breathing trial) and selected a preferred technique for the breathing trials. With regard to the patient they were visiting, respondents identified the most important outcome to them at ICU admission, during the ICU stay, and at ICU discharge.

MEASUREMENTS AND MAIN RESULTS

We analyzed 322 questionnaires (95.5% response rate). All outcomes were highly rated (average range: 7.82-9.74). Across scenarios, outcomes rated as most important were ICU and hospital survival (9.72, 9.70), avoiding complications (9.45), quality of life (9.394), patient comfort (9.393), and returning to previous living arrangements (9.31). Overall, the most important ventilation-related outcomes were being ventilator-free (8.95), avoiding reintubation (8.905), and passing a spontaneous breathing trial (8.903). Passing a spontaneous breathing trial assumed greater importance after an initial failed attempt. "Time to event" outcomes were less important to visitors. We did not identify a preferred spontaneous breathing trial technique. Although ICU survival was the most important outcome at ICU admission and during the ICU stay, visitors rated quality of life higher than hospital survival at ICU discharge.

CONCLUSIONS

Visitors to critically ill patients prioritized two general outcomes (ICU and hospital survival) and three ventilation-related outcomes (being ventilator free, avoiding reintubation, passing a spontaneous breathing trial), and valued avoiding complications, maintaining quality of life, comfort, and returning to previous living arrangements. The outcomes preferences of the survey respondents evolved temporally during the ICU stay.

Airway Management Strategies for Brain-injured Patients Meeting Standard Criteria to Consider Extubation. A Prospective Cohort Study

RATIONALE

Patients with acute brain injury are frequently capable of breathing spontaneously with minimal ventilatory support despite persistent neurological impairment.

OBJECTIVES

We sought to describe factors associated with extubation timing, success, and primary tracheostomy in these patients.

METHODS

We conducted a prospective multicenter observational cohort study in three academic hospitals in Toronto, Canada. Consecutive brain-injured adults receiving mechanical ventilation for at least 24 hours in three intensive care units were screened by study personnel daily for extubation consideration criteria. We monitored all patients until hospital discharge and used logistic regression models to examine associations with extubation failure and delayed extubation.

MEASUREMENTS AND MAIN RESULTS

Of 192 patients included, 152 (79%) were extubated and 40 (21%) received a tracheostomy without an extubation attempt. The rate of extubation failure within 72 hours was 32 of 152 (21%), which did not vary significantly between those extubated before (early; 6 of 37; 16.2%), within 24 hours (timely; 14 of 70; 20.0%), or more than 24 hours after meeting criteria to consider extubation (delayed; 12 of 45; 26.7%; P = 0.49). Delayed extubation was associated with lower a Glasgow Coma Scale (GCS) score at the time of consideration of extubation, absence of cough, and new positive sputum cultures. Factors independently associated with successful extubation were presence of cough (odds ratio [OR], 3.60; 95% confidence interval [CI], 1.42-9.09), fluid balance in prior 24 hours (OR, 0.75 per 1-L increase; 95% CI, 0.57-0.98), and age (OR, 0.97 per 10-yr increase; 95% CI, 0.95-0.99). A higher GCS score was not associated with successful extubation.

CONCLUSIONS

Extubation success was predicted by younger age, presence of cough, and negative fluid balance, rather than GCS score at extubation. These results do not support prolonging intubation solely for low GCS score in brain-injured patients.

Care of patients undergoing weaning from mechanical ventilation in critical care

There are several reasons why mechanical ventilation - the use of an artificial device to assist a patient to breathe - may be initiated, for example to enable general anaesthesia for patients undergoing surgery, and for those with a compromised airway or respiratory failure. It is important that critical care nurses have the skills and knowledge to care for patients who are undergoing weaning from mechanical ventilation. This is to ensure that patients are weaned safely and as soon as possible, to improve their outcomes and avoid an increase in patient mortality and morbidity through complications that can arise such as airway trauma and ventilator-associated pneumonia. Furthermore, there are resource and cost implications of patients not being weaned as soon as possible.