Weaning from ventilatory support

Development and performance assessment of a novel scroll compressor-based oxygen generator integrated ventilator

Current ventilators rely on wall outlets or cylinders for oxygen supply, which limits their continuous use in the field or emergencies. In this study, we proposed a ventilator prototype that can achieve stand-alone oxygenated respiratory support, by designing and integrating a high-performance oxygen generator, and optimizing the control strategies of the whole system. Based on the designed oil-free scroll compressor and pressure swing adsorption (PSA) system, we first realized a mobile high-flow oxygen generator, which achieved an output flow greater than 17 L/min with an oxygen concentration of 93% ± 3%. The ventilator was also designed to synchronize with the respiratory state, to optimize the trigger performance for the pressure support of early inspiration, and reduce the gas supply in the late inspiratory phase to avoid pressure overshoot in the early expiratory phase. The respiratory synchronization of the integrated ventilator was estimated by the recorded chest movement of the subjects. Satisfactory respiratory synchronization was realized with an inspiratory trigger delay (ITD) time of less than 200 ms and sound respiratory waveform tracking. By regulating the PSA strategy, the oxygen generation and utilization efficiencies could be further improved. Ultimately, under the setting of inspiratory positive airway pressure (IPAP) at 10 cmH2O, and expiratory positive airway pressure (EPAP) at 4 cmH2O, we achieved non-invasive ventilation with a maximum oxygen concentration of 58% ± 1.75%. In conclusion, the proposed oxygen generator integrated ventilator could provide reliable oxygenated respiratory support in emergencies, such as on-site first aid, patient transport, and military field environments.

Renal Function Markers Predicts Extubation Failure in Critically Ill Patients: A Retrospective Study

Several studies attempt to identify predictors for weaning and extubation from mechanical ventilation (MV) and none have been shown to be particularly accurate. Therefore, the objective of the study was to evaluate whether markers of renal function may be associated with extubation failure. This retrospective study collected data through electronic medical records for 2 consecutive years. The inclusion criteria were: ≥18 years old and requiring invasive MV for a period of ≥48 hours. Extubation failure was determined when subjects needed to return to invasive MV within 48 hours of the tracheal tube withdrawal. Acute kidney injury (AKI) was assessed according to the KDIGO classification. From a total of 167 subjects, 15% evolved with extubation failure. Lower creatinine clearance and higher fluid balance was observed in the extubation failure group compared to the successful extubation group (42 mL/min vs 100 mL/min, P = 0.01 and 739 mL vs - 189 mL, P = 0.01, respectively). Subjects with AKI are 51% more likely to evolve with extubation failures than those with normal renal function (OR = 2.7; 95% CI: 1.6-4.7; P < 0.01). Renal dysfunction was related to the rate of extubation failure. Fluid balance and serum creatinine may be aspects to be considered when making the extubation decision.

Effect of high-flow nasal cannula therapy on mechanical ventilation duration in the pediatric intensive care unit

BACKGROUND

High-flow nasal cannula (HFNC) therapy has gained popularity in the pediatric intensive care unit (PICU). However, the nationwide effect of HFNC on mechanical ventilation duration has not been studied.

METHODS

We retrospectively analyzed pediatric patients (28 days to 17 years old) admitted to tertiary ICUs for respiratory support from 2012 to 2019 using the Korean National Health Insurance database. Pre-/post-HFNC periods were defined as the 12 months before and after the application of HFNC in any hospital, respectively, allowing a 6-month transition period. Mechanical ventilation duration and ventilator-free days during these two periods were compared using a multivariable regression model.

RESULTS

Using data from 46 hospitals, 4,705 and 4,864 respective pre-/post-HFNC period patients were evaluated. During the post-HFNC period, 14.8% of patients were treated by HFNC, and 67.1% were treated using invasive mechanical ventilation. In adjusted analysis, mechanical ventilation duration was reduced by 0.99 days (confidence interval [CI]: -1.86, -0.12). The duration was significantly reduced by 17.81 days (CI: -35.46, -0.16) among patients whose ventilation duration was longer than 28 days. In subgroup analysis, mechanical ventilation duration was reduced by 1.49 days (CI: -2.78, -0.19) in the overall surgical group and 6.71 days (CI: -11.71, - 1.71) in the neurologic subgroup. Ventilator-free days were increased only in the overall surgical group, by 0.31 days (CI: 0.01, 0.61).

CONCLUSIONS

Application of HFNC to PICU patients could reduce mechanical ventilation duration, especially in patients requiring prolonged mechanical ventilator support or in post-operative patients.

Development of a Machine Learning Model for Predicting Weaning Outcomes Based Solely on Continuous Ventilator Parameters during Spontaneous Breathing Trials

Discontinuing mechanical ventilation remains challenging. We developed a machine learning model to predict weaning outcomes using only continuous monitoring parameters obtained from ventilators during spontaneous breathing trials (SBTs). Patients who received mechanical ventilation in the medical intensive care unit at a tertiary university hospital from 2019-2021 were included in this study. During the SBTs, three waveforms and 25 numerical data were collected as input variables. The proposed convolutional neural network (CNN)-based weaning prediction model extracts features from input data with diverse lengths. Among 138 enrolled patients, 35 (25.4%) experienced weaning failure. The dataset was randomly divided into training and test sets (8:2 ratio). The area under the receiver operating characteristic curve for weaning success by the prediction model was 0.912 (95% confidence interval [CI], 0.795-1.000), with an area under the precision-recall curve of 0.767 (95% CI, 0.434-0.983). Furthermore, we used gradient-weighted class activation mapping technology to provide visual explanations of the model's prediction, highlighting influential features. This tool can assist medical staff by providing intuitive information regarding readiness for extubation without requiring any additional data collection other than SBT data. The proposed predictive model can assist clinicians in making ventilator weaning decisions in real time, thereby improving patient outcomes.

Comparison of the timed inspiratory effort index with the T-piece trial as a decision-making tool for extubation: a randomized controlled non-inferiority trial

The "timed inspiratory effort" (TIE) index, a new predictor of weaning outcome, normalizes the maximal inspiratory pressure with the time required to reach this value up to 60 s, incorporating the time domain into the assessment of inspiratory muscle function. The objective of this study was to determine whether the TIE predicts successful extubation at a similar rate as the T-piece trial with less time required. A non-inferiority randomized controlled trial was performed with ICU subjects eligible for weaning. The participants were allocated to the TIE or the T-piece groups. The primary outcome was successful weaning, and the main secondary outcome was ICU mortality. Eighty participants of each group were included in the final analysis. Time from the start of a successful test to effective extubation was significantly lower in the TIE group than in the T-piece group, 15 (10 to 24) vs 55 (40 to 75) min, P<0.001. In the Kaplan-Meier analysis, no significant differences were found in successful weaning (79.5 vs 82.5%, P=0.268) or survival rate (62.9 vs 53.8%, P=0.210) between the TIE and T-piece groups at the 30th day. In this preliminary study, the TIE index was not inferior to the T-piece trial as a decision-making tool for extubation and allowed a reduction in the decision time.

Opioid-free anesthesia with lidocaine for improved postoperative recovery in hysteroscopy: a randomized controlled trial

BACKGROUND

Anesthesia with opioids negatively affects patients' quality of recovery. Opioid-free anesthesia attempts to avoid these effects. This study aimed to evaluate the effect of opioid-free anesthesia on the quality of recovery, using lidocaine on patients undergoing hysteroscopy.

METHODS

A parallel-group, randomized, double-blind, controlled trial was conducted in Yichang Central Peoples' Hospital, Hubei Province, China, from January to April, 2022. We included 90 female patients (age: 18-65 years, American Society of Anesthesiologists Physical Status Class I-II) scheduled for elective hysteroscopy, 45 of whom received lidocaine (Group L), and 45 received sufentanil (Group S). Patients were randomly allocated to receive either lidocaine or sufentanil perioperatively. The primary outcome was the quality of postoperative recovery, which was assessed using the QoR-40 questionnaire (a patient-reported outcome questionnaire measuring the quality of recovery after surgery).

RESULTS

The two groups were similar in age, American Society of Anesthesiology physical status, height, weight, body mass index, and surgical duration. The QoR scores were significantly higher in Group L than Group S. The incidence of postoperative nausea and vomiting, as well as the time to extubation were significantly lower in Group L than Group S.

CONCLUSION

Opioid-free anesthesia with lidocaine achieves a better quality of recovery, faster recovery, and a shorter time to extubation than general anesthesia with sufentanil.

TRIAL REGISTRATION

The trial was registered on January 15, 2022 in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/showprojen.aspx?proj=149386 ), registration number ChiCTR2200055623.(15/01/2022).

Comparison of High-Flow Nasal Cannula Versus Conventional Oxygen Therapy After Extubation in Children Undergoing Cardiac Surgery: A Meta-analysis

This meta-analysis aims to compare high-flow nasal cannula (HFNC) and conventional oxygen therapy (COT) post-extubation in pediatric cardiac surgical patients. The present meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two authors independently searched three electronic databases including PubMed, Embase, and the Cochrane Library to identify relevant articles published in English from inception to February 2023. Searching was conducted using keywords and medical subject headings (MeSH), which included "conventional oxygen therapy," "high-flow nasal cannula," "extubation," "pediatrics," and "cardiac surgery." Our primary outcome was extubation failure defined as the need for reintubation within 24 to 72 hours after planned extubation. Secondary outcomes assessed in this meta-analysis included partial pressure of arterial oxygen (PaO2), partial pressure of arterial carbon dioxide (PaCO2), and the ratio of PaO2 and FiO2 (fraction of inspired oxygen). A total of three studies were included in the meta-analysis, with a total of 227 patients.  No significant difference was found between the two groups (the HFNC group and the COT group) in terms of reintubation (RR: 0.88, 95% CI: 0.34, 2.30, p-value: 0.80). Pooled meta-analysis showed that PaO2 was significantly greater in patients receiving HFNC at six hours (MD: 33.73, 95% CI: 18.33, 49.14, p-value<0.001), at 12 hours (MD: 44.90, 95% CI: 28.59, 61.22, p-value<0.001) and at 24 hours (MD: 43.53, 95% CI: 29.16, 57.91, p-value<0.001) of extubation. PaCO2 was significantly lower in patients receiving HFNC at six hours (MD: -5.40, 95% CI: -7.94, -2.85, p-value<0.001) and at 12 hours (MD: -5.93, 95% CI: -9.78, -2.09, p-value<0.001) of extubation. However, no significant difference was reported between the two groups after 24 hours of extubation (MD: -0.84, 95% CI: -9.04, 7.37, p-value: 0.84) and PaO2/FiO2 was significantly greater in patients receiving HFNC at six hours (MD: 64.14, 95% CI: 36.10, 92.17, p-value<0.001), at 12 hours (MD: 70.73, 95% CI: 20.46, 121.01, p-value<0.001) and at 24 hours (MD: 82.18, 95% CI: 50.03, 114.32, p-value<0.001) of intubation. In conclusion, the meta-analysis revealed that compared with COT, HFNC significantly increased PaO2 and the ratio of PaO2 to FiO2, and decreased PaCO2. No significant differences were observed in the rate of reintubation between the two groups. This is the first meta-analysis comparing HFNC and COT in pediatric cardiac surgical patients.

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.

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

BACKGROUND

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

METHODS

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

DISCUSSION

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

TRIAL REGISTRATION

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

Noninvasive and invasive mechanical ventilation for neurologic disorders

Patients with acute neurologic injuries frequently require mechanical ventilation due to diminished airway protective reflexes, cardiopulmonary failure secondary to neurologic insults, or to facilitate gas exchange to precise targets. Mechanical ventilation enables tight control of oxygenation and carbon dioxide levels, enabling clinicians to modulate cerebral hemodynamics and intracranial pressure with the goal of minimizing secondary brain injury. In patients with acute spinal cord injuries, neuromuscular conditions, or diseases of the peripheral nerve, mechanical ventilation enables respiratory support under conditions of impending or established respiratory failure. Noninvasive ventilatory approaches may be carefully considered for certain disease conditions, including myasthenia gravis and amyotrophic lateral sclerosis, but may be inappropriate in patients with Guillain-Barré syndrome or when relevant contra-indications exist. With regard to discontinuing mechanical ventilation, considerable uncertainty persists about the best approach to wean patients, how to identify patients ready for extubation, and when to consider primary tracheostomy. Recent consensus guidelines highlight these and other knowledge gaps that are the focus of active research efforts. This chapter outlines important general principles to consider when initiating, titrating, and discontinuing mechanical ventilation in patients with acute neurologic injuries. Important disease-specific considerations are also reviewed where appropriate.

Comparative Efficacy and Safety of Four Different Spontaneous Breathing Trials for Weaning From Mechanical Ventilation: A Systematic Review and Network Meta-Analysis

Background: Spontaneous breathing trial (SBT) has been used to predict the optimal time of weaning from ventilator. However, it remains controversial which trial should be preferentially selected. We aimed to compare and rank four common SBT modes including automatic tube compensation (ATC), pressure support ventilation (PSV), continuous positive airway pressure (CPAP), and T-piece among critically ill patients receiving mechanical ventilation (MV).

Methods: We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies that investigated the comparative efficacy and safety of at least two SBT strategies among critically ill patients up to May 17, 2020. We estimated the surface under the cumulative ranking curve (SUCRA) to rank SBT techniques, and determined the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation method. Primary outcome was weaning success. Secondary outcomes were reintubation, SBT success, duration of acute care, and intensive care unit (ICU) mortality. Statistical analysis was conducted by using RevMan 5.4, Stata, and R software.

Results: We enrolled 24 trials finally. Extubation success rate was significantly higher in ATC than that in T-piece (OR, 0.28; 95% CI, 0.13–0.64) or PSV (OR, 0.53; 95% CI, 0.32–0.88). For SBT success, ATC was better than other SBT techniques, with a pooled OR ranging from 0.17 to 0.42. For reintubation rate, CPAP was worse than T-piece (OR, 2.76; 95% CI, 1.08 to 7.06). No significant difference was detected between SBT modes for the length of stay in ICU or long-term weaning unit (LWU). Similar result was also found for ICU mortality between PSV and T-piece. Majority direct results were confirmed by network meta-analysis. Besides, ATC ranks at the first, first, and fourth place with a SUCRA of 91.7, 99.7, and 39.9%, respectively in increasing weaning success and SBT success and in prolonging ICU or LWU length of stay among four SBT strategies. The confidences in evidences were rated as low for most comparisons.

Conclusion: ATC seems to be the optimal choice of predicting successful weaning from ventilator among critically ill patients. However, randomized controlled trials (RCTs) with high quality are needed to further establish these findings.

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.

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

Objetivo

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

Métodos

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

Resultados

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

Conclusão

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

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

BACKGROUND

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

RESEARCH QUESTION

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

STUDY DESIGN AND METHODS

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

RESULTS

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

INTERPRETATION

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

TRIAL REGISTRY

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

Mechanical ventilation strategy for pulmonary rehabilitation based on patient-ventilator interaction

Mechanical ventilation is an effective medical means in the treatment of patients with critically ill, COVID-19 and other pulmonary diseases. During the mechanical ventilation and the weaning process, the conduct of pulmonary rehabilitation is essential for the patients to improve the spontaneous breathing ability and to avoid the weakness of respiratory muscles and other pulmonary functional trauma. However, inappropriate mechanical ventilation strategies for pulmonary rehabilitation often result in weaning difficulties and other ventilator complications. In this article, the mechanical ventilation strategies for pulmonary rehabilitation are studied based on the analysis of patient-ventilator interaction. A pneumatic model of the mechanical ventilation system is established to determine the mathematical relationship among the pressure, the volumetric flow, and the tidal volume. Each ventilation cycle is divided into four phases according to the different respiratory characteristics of patients, namely, the triggering phase, the inhalation phase, the switching phase, and the exhalation phase. The control parameters of the ventilator are adjusted by analyzing the interaction between the patient and the ventilator at different phases. A novel fuzzy control method of the ventilator support pressure is proposed in the pressure support ventilation mode. According to the fuzzy rules in this research, the plateau pressure can be obtained by the trigger sensitivity and the patient's inspiratory effort. An experiment prototype of the ventilator is established to verify the accuracy of the pneumatic model and the validity of the mechanical ventilation strategies proposed in this article. In addition, through the discussion of the patient-ventilator asynchrony, the strategies for mechanical ventilation can be adjusted accordingly. The results of this research are meaningful for the clinical operation of mechanical ventilation. Besides, these results provide a theoretical basis for the future research on the intelligent control of ventilator and the automation of weaning process.

Preventive use of respiratory support after scheduled extubation in critically ill medical patients-a network meta-analysis of randomized controlled trials

BACKGROUND

Respiratory support has been increasingly used after extubation for the prevention of re-intubation and improvement of prognosis in critically ill medical patients. However, the optimal respiratory support method is still under debate. This network meta-analysis (NMA) aims to evaluate the comparative effectiveness of various respiratory support methods used for preventive purposes after scheduled extubation in critically ill medical patients.

METHODS

A systematic database search was performed from inception to December 19, 2019, for randomized controlled trials (RCTs) that compared a preventive use of different respiratory support methods, including conventional oxygen therapy (COT), noninvasive ventilation (NIV), high-flow oxygen therapy (HFOT), and combinational use of HFOT and NIV (HFOT+NIV), after planned extubation in adult critically ill medical patients. Study selection, data extraction, and quality assessments were performed in duplicate. The primary outcomes included re-intubation rate and short-term mortality.

RESULTS

Seventeen RCTs comprising 3341 participants with 4 comparisons were included. Compared with COT, NIV significantly reduced the re-intubation rate [risk ratio (RR) 0.55, 95% confidence interval (CI) 0.39 to 0.77; moderate quality of evidence] and short-term mortality (RR 0.66, 95% CI 0.48 to 0.91; moderate quality of evidence). Compared to COT, HFOT had a beneficial effect on the re-intubation rate (RR 0.55, 95% CI 0.35 to 0.86; moderate quality of evidence) but no effect on short-term mortality (RR 0.79, 95% CI 0.56 to 1.12; low quality of evidence). No significant difference in the re-intubation rate or short-term mortality was found among NIV, HFOT, and HFOT+NIV. The treatment rankings based on the surface under the cumulative ranking curve (SUCRA) from best to worst for re-intubation rate were HFOT+NIV (95.1%), NIV (53.4%), HFOT (51.2%), and COT (0.3%), and the rankings for short-term mortality were NIV (91.0%), HFOT (54.3%), HFOT+NIV (43.7%), and COT (11.1%). Sensitivity analyses of trials with a high risk of extubation failure for the primary outcomes indicated that the SUCRA rankings were comparable to those of the primary analysis.

CONCLUSIONS

After scheduled extubation, the preventive use of NIV is probably the most effective respiratory support method for comprehensively preventing re-intubation and short-term death in critically ill medical patients, especially those with a high risk of extubation failure.

Positive Pressure Ventilation in Cardiogenic Shock: Review of the Evidence and Practical Advice for Patients With Mechanical Circulatory Support

Cardiogenic shock (CS) is often complicated by respiratory failure, and more than 80% of patients with CS require respiratory support. Elevated filling pressures from left-ventricular (LV) dysfunction lead to alveolar pulmonary edema, which impairs both oxygenation and ventilation. The implementation of positive pressure ventilation (PPV) improves gas exchange and can improve cardiovascular hemodynamics by reducing preload and afterload of the LV, reducing mitral regurgitation and decreasing myocardial oxygen demand, all of which can help augment cardiac output and improve tissue perfusion. In right ventricular (RV) failure, however, PPV can potentially decrease preload and increase afterload, which can potentially lead to hemodynamic deterioration. Thus, a working understanding of cardiopulmonary interactions during PPV in LV and RV dominant CS states is required to safely treat this complex and high-acuity group of patients with respiratory failure. Herein, we provide a review of the published literature with a comprehensive discussion of the available evidence on the use of PPV in CS. Furthermore, we provide a practical framework for the selection of ventilator settings in patients with and without mechanical circulatory support, induction, and sedation methods, and an algorithm for liberation from PPV in patients with CS.

Outcomes of mechanical ventilation according to WIND classification in pediatric patients

Background

The outcomes of weaning processes are not well known in pediatric patients, and the International Conference Classification on weaning from mechanical ventilation showed limited application. We evaluate the relationship between the new Weaning according to a New Definition (WIND) classification and outcome in pediatric patients.

Methods

We conducted a retrospective cohort study in a tertiary pediatric intensive care unit (ICU). We included patients under 18 years of age who received invasive mechanical ventilation for more than 24 h and excluded cases with other than the first ICU admissions, tracheostomy with home ventilation before admission, intubation or weaning processes conducted in other ICU, and weaning with extracorporeal membrane oxygenation. Weaning processes were classified into four groups according to weaning duration after the first separation attempt (SA): no-SA, short weaning (< 24 h), difficult weaning (24 h–7 days), and prolonged weaning (> 7 days). Mortality rates were compared across groups using the Kruskal–Wallis test, and risk factors for the no-SA group were analyzed by multivariate logistic regression tests with age, sex, severity score at admission, admission type, and underlying disease as variables.

Results

Among 313 patients, 224 were enrolled and had a median age of 2.1 (interquartile range 0.5–6.6) years. Spontaneous breathing tests were done in 70.1% of enrolled patients. The median duration of intubation to the first SA was 4 (range 0–36) days, and 92.8% patients underwent the first SA within 14 days. The mortality rate was 0% in the short (0/99) and difficult (0/53) weaning groups and 17.9% (5/28) in the prolonged weaning group (p < 0.001). The mortality rate of the no-SA group was 93.2% (41/44). Admission severity (hazard ratio 1.036, confidence interval 1.022–1.050) and underlying oncologic disease (hazard ratio 7.341, confidence interval 3.008–17.916) were independent risk factors for lack of SA.

Conclusions

In conclusion, WIND classification is associated with ICU mortality in pediatric patients. Further studies of this association are required to improve protocols associated with the weaning process and clinical outcomes.

Trial registration Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0547-2) contains supplementary material, which is available to authorized users.

High-flow nasal cannula oxygen therapy versus conventional oxygen therapy in patients after planned extubation: a systematic review and meta-analysis

BACKGROUND

The effect of high-flow nasal cannula (HFNC) therapy in patients after planned extubation remains inconclusive. We aimed to perform a rigorous and comprehensive systematic meta-analysis to robustly quantify the benefits of HFNC for patients after planned extubation by investigating postextubation respiratory failure and other outcomes.

METHOD

We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Library from inception to August 2018. Two researchers screened studies and collected the data independently. Randomized controlled trials (RCTs) and crossover studies were included. The main outcome was postextubation respiratory failure.

RESULTS

Ten studies (seven RCTs and three crossover studies; HFNC group: 856 patients; Conventional oxygen therapy (COT) group: 852 patients) were included. Compared with COT, HFNC may significantly reduce postextubation respiratory failure (RR, 0.61; 95% CI, 0.41, 0.92; z = 2.38; P = 0.02) and respiratory rates (standardized mean differences (SMD), - 0.70; 95% CI, - 1.16, - 0.25; z = 3.03; P = 0.002) and increase PaO₂ (SMD, 0.30; 95% CI, 0.04, 0.56; z = 2.23; P = 0.03). There were no significant differences in reintubation rate, length of ICU and hospital stay, comfort score, PaCO₂, mortality in ICU and hospital, and severe adverse events between HFNC and COT group.

CONCLUSIONS

Our meta-analysis demonstrated that compared with COT, HFNC may significantly reduce postextubation respiratory failure and respiratory rates, increase PaO₂, and be safely administered in patients after planned extubation. Further large-scale, multicenter studies are needed to confirm our results.

Effects of manual chest compression on expiratory flow bias during the positive end-expiratory pressure-zero end-expiratory pressure maneuver in patients on mechanical ventilation

OBJECTIVE

To investigate the effects of manual chest compression (MCC) on the expiratory flow bias during the positive end-expiratory pressure-zero end-expiratory pressure (PEEP-ZEEP) airway clearance maneuver applied in patients on mechanical ventilation. The flow bias, which influences pulmonary secretion removal, is evaluated by the ratio and difference between the peak expiratory flow (PEF) and the peak inspiratory flow (PIF).

METHODS

This was a crossover randomized study involving 10 patients. The PEEP-ZEEP maneuver was applied at four time points, one without MCC and the other three with MCC, which were performed by three different respiratory therapists. Respiratory mechanics data were obtained with a specific monitor.

RESULTS

The PEEP-ZEEP maneuver without MCC was enough to exceed the threshold that is considered necessary to move secretion toward the glottis (PEF - PIF difference > 33 L/min): a mean PEF - PIF difference of 49.1 ± 9.4 L/min was achieved. The mean PEF/PIF ratio achieved was 3.3 ± 0.7. Using MCC with PEEP-ZEEP increased the mean PEF - PIF difference by 6.7 ± 3.4 L/min. We found a moderate correlation between respiratory therapist hand grip strength and the flow bias generated with MCC. No adverse hemodynamic or respiratory effects were found.

CONCLUSIONS

The PEEP-ZEEP maneuver, without MCC, resulted in an expiratory flow bias superior to that necessary to facilitate pulmonary secretion removal. Combining MCC with the PEEP-ZEEP maneuver increased the expiratory flow bias, which increases the potential of the maneuver to remove secretions.

Prospective Observational Study on Evaluation of Cardiac Dysfunction Induced during the Weaning Process

Context

Weaning induced cardiac dysfunction can occur without underlying heart disease. Changes in intrathoracic pressure, systemic vascular resistance, preload and afterload leading to heart-lung interactions are the possible explanatory mechanisms

Aims

The aim of the current study was whether the assessment and identification of cardiac dysfunction induced during the weaning process could predict the outcome of extubation.

Settings and design

A prospective observational study with convenience sampling method was conducted from May 2015 to April 2016 after institutional ethical committee approval (ref 161/2015).

Materials and methods

Patients over eighteen and planned for extubation were included. Weaning method used was a spontaneous breathing trial (SBT) by pressure support-positive end-expiratory pressure (PS-PEEP). Baseline characteristics, weaning, and echocardiography parameters were collected pre extubation. Post-extubation echocardiographic parameters were collected within six hours as per the protocol. The primary outcome was extubation failure (reintubation within 48 hours). Secondary outcomes were ICU length of stay and ICU mortality.

Statistical analysis

Statistical method used is STATA™ (Version14, College Station TX).

Results

Out of one hundred and sixty-one patients, twenty-one failed extubation (13.04 %). Pre-extubation echocardiographic parameters were similar in two groups except for preexisting LV systolic dysfunction. Post-extubation E/e` (9.30 vs. 7.71 p = 0.018) was higher in the extubation failure group. Extubation failure group had higher intensive care unit (ICU) length of stay and ICU mortality.

Conclusion

In our study E/e` during a weaning trial did not predict extubation success. Cardiac dysfunction induced during weaning may get masked during weaning and manifests postextubation. This needs to be verified in subsequent studies.

Key messages

Cardiac dysfunction induced during the weaning process may get masked and manifests post-extubation. Echocardiographic assessment during the weaning process and post-extubation helps to evaluate and identify the patients at risk of reintubation.

How to cite this article

Amarja H, Bhuvana K, Sriram S. Prospective Observational Study on Evaluation of Cardiac Dysfunction Induced during the Weaning Process. Indian Journal of Critical Care Medicine, January 2019;23(1):15-19.

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.

Budesonide facilitates weaning from mechanical ventilation in difficult-to-wean very severe COPD patients: Association with inflammatory mediators and cells

INTRODUCTION

Mechanical ventilatory support is life-saving therapy for patients with respiratory failure in intensive care units (ICU) but is linked to ventilator-associated pneumonia and other nosocomial infections. Interventions that improve the efficiency of weaning from mechanical ventilation may improve patient outcomes.

OBJECTIVE

To determine whether inhaled budesonide decreases time-to-weaning in COPD stage 4 difficult-to-wean patients and reduces the release of pro-inflammatory cytokines in ICU patients.

MATERIALS AND METHODS

We recruited 55 difficult-to-wean COPD patients (Stage 4) within the ICU of the Masih Daneshvari Hospital. Subjects were randomly assigned to receive inhaled budesonide (0.5mg/day) or placebo (normal saline). Dynamic compliance and BAL cytokines were measured.

RESULTS

Budesonide significantly reduced the number of days on MV (days-to-weaning=4.6±1.6days) compared to that seen in the control group (7.2±2.7days, p=0.014). Dynamic compliance was significantly improved in the budesonide group on days 3 (p=0.018) and 5 (p=0.011) The levels of CXCL-8 and IL-6 diminished on days 3-5 after start of budesonide (p<0.05).

CONCLUSION

In COPD patients on MV, nebulized budesonide was associated with reduced BAL CXCL8 and IL-6 levels and neutrophil numbers as well as an improvement in ventilatory mechanics and facilitated weaning.

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.

Comparing the efficacy and safety of laryngeal mask airway, streamlined liner of the pharyngeal airway and I-gel following tracheal extubation

Adverse events following surgical operations are common complications due to removal of tracheal tube in contrast to the tracheal intubation. Awareness about the new methods and strategies for tracheal tube extubation is necessary for a safe and successful extubation. Therefore, we aimed to assess the safety and efficacy of laryngeal mask airway (LMA), streamlined liner of the pharyngeal airway (SLIPA) and I-gel in extubation time of tracheal tube. A one-single randomized clinical trial was conducted in 105 eligible patients in three groups including LMA, SLIPA and I-gel. The patients were under surgery after general anesthesia with propofol (2-3 mg/kg) and fentanyl (1-2 μg/kg). Hemodynamic responses and extubation consequences including coughing rate, laryngospasm, airway obstruction, apnea, breath holding and straining of patients, vomiting, and need for re-intubation were recorded every 5 minutes since inserting of supraglottic airway devices (SADs) until patients restore consciousness. Analysis of data was conducted in SPSS software by analysis of variance (ANOVA) and ANOVA for repeated measurements tests. The overall successful insertion was 100% for LMA and I-Gel and this rate was 97.1% for SLIPA method. A significant decrease was observed in trend of hemodynamic responses in all three groups. Nevertheless, the MBP was lower in LMA group and lower HR was observed in I-Gel and higher HR occurred in SLIPA (P < 0.05). Three groups was same statistically regarding sore throat, vomiting, coughing, breath holding, apnea, laryngospasm, and re-intubation need (P > 0.05). However, the incidence rate of apnea, and laryngospasm, as well as re-intubation need in SLIPA group was 2.9%, respectively. LMA, I-GEL and SLIPA could be considered as useful and safe devices for ventilation control after tracheal tube removal at the end of operation. Three devices were same regarding to sore throat, vomiting, coughing, and breath holding. However, LMA showed lower side effects while SLIPA was related to more occurrences of apnea, laryngospasm, and re-intubation need.

Monitoring of Electrical Activity of the Diaphragm Shows Failure of T-Piece Trial Earlier than Protocol-Based Parameters in Prolonged Weaning in Non-communicative Neurological Patients

BACKGROUND

The weaning target in tracheotomised patients is not extubation, but spontaneous breathing without the support of a ventilator. Overloading the respiratory pump during such spontaneous breathing trials is unfavorable, prolongs weaning time, and increases morbidity and mortality. The goal of this study was to evaluate the electrical activity of the diaphragm during a t-piece trial in non-communicative neurological patients and the comparison to clinical parameters of exhaustion.

METHODS

During multiple t-piece trials, the electrical activity of the diaphragm was obtained before, during and after the end of the trial. T-piece trials were grouped based on the reason for stopping the trial (exhaustion or allotted time period).

RESULTS

Twenty-nine tracheotomised patients in prolonged weaning (29 ± 22 days ventilated at the start of the study) were included in a prospective observational study. T-piece trials (n = 152; 5 ± 2 per patient) were grouped based on the reason for stopping the trial (n = 91 because of exhaustion; n = 61 because of the allotted time period). We found that the electrical activity of the diaphragm exhibits an earlier increase than protocol-based clinical parameters in patients who failed the trial due to exhaustion. The electrical activity of the diaphragm shows no relevant difference during the t-piece trial in patients in whom the trial was stopped due to the allotted time period per protocol.

CONCLUSIONS

Monitoring the electrical activity of the diaphragm in non-communicative neurological patients in prolonged weaning allows earlier detection of exhaustion than protocol-based parameters.

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.

Mechanical ventilation weaning protocol improves medical adherence and results

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tracheostomy, Extubation, Reintubation: Airway Management Decisions in Intubated Stroke Patients

BACKGROUND

Both delayed and premature extubation increase complication rate, the need for tracheostomy (TT), the duration of intensive care unit stay, and mortality. In this study, we therefore investigated factors associated with primary TT and predictors for extubation failure (EF) in a sample of severely affected ventilated stroke patients.

METHODS

One hundred eighty five intubated stroke patients were prospectively analyzed in this observational study. Patients not meeting predefined clinical and respiratory extubation criteria received a TT. All other patients were extubated and followed up for the need of reintubation. Characteristics of patients with and without extubation attempt were examined. Additionally, within the group of extubated patients, subgroups of successfully vs. unsuccessfully extubated patients were compared. Clinical factors associated with reintubation, including a previously established semi-quantitative airway score, were determined and predictors of EF were assessed.

RESULTS

Ninety-eight of 185 patients (53%) were primarily extubated; EF rate was 37% (36 patients). Eighty-seven (47%) were tracheostomized without a prior extubation attempt. Primarily tracheostomized patients had more severe strokes, which were more often hemorrhagic, presented with a lower level of consciousness, needed neurosurgical intervention more often, had a higher rate of obesity, and were more frequently intubated because of suspicion of compromised protective reflexes. EF was independently predicted by prior neurosurgical treatment and low airway management scores. No differences were found for the ability to follow simple commands and classical weaning criteria.

CONCLUSION

Airway management decisions in intubated stroke patients represent a clinical challenge. Classical weaning criteria and parameters reflecting the patient's state of consciousness are not reliably predictive of extubation success. Criteria more closely related to airway safety and secretion handling may provide the most relevant information and should therefore be assessed by specific clinical scoring systems.

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.

Influence of inspiratory muscle training on weaning patients from mechanical ventilation: a systematic review

Abstract Introduction: The inability of respiratory muscles to generate force and endurance is recognized as an important cause of failure in weaning patients from invasive mechanical ventilation (IMV). Thus, inspiratory muscle training (IMT) might be an interesting treatment option for patients with prolonged IMV weaning. Objective: The aim of this systematic literature review was to evaluate the effectiveness of inspiratory muscle training in weaning patients from mechanical ventilation and to identify the most effective type of training for this particular purpose. Methods: We searched PubMed, LILACS, PEDro and Web of Science for randomized clinical trials published in English or Portuguese from January 1990 until March 2015. Results: Eighty-nine studies were identified of which five were selected. A total of 267 patients participated in the five randomized clinical trials analyzed here. IMV duration before onset of training varied greatly among subjects. Three studies performed IMT using a threshold device and two studies used adjustments of ventilator pressure sensitivity. Four studies have shown that IMT resulted in a significant increase in inspiratory maximal pressure. Only two studies, however, have reported that IMT resulted in higher success rates in weaning patients from IMV. One study has found that patients showed a shorter ventilator weaning duration after IMT. Conclusion: IMT using pressure threshold devices results in increased inspiratory muscle strength and can therefore be considered a more effective treatment option and with the potential to optimize ventilator weaning success in patients at risk of prolonged IMV.

Mechanical ventilation in patients in the intensive care unit of a general university hospital in southern Brazil: an epidemiological study

OBJECTIVES

To determine the characteristics, the frequency and the mortality rates of patients needing mechanical ventilation and to identify the risk factors associated with mortality in the intensive care unit (ICU) of a general university hospital in southern Brazil.

METHOD

Prospective cohort study in patients admitted to the ICU who needed mechanical ventilation for at least 24 hours between March 2004 and April 2007.

RESULTS

A total of 1,115 patients admitted to the ICU needed mechanical ventilation. The mortality rate was 51%. The mean age (± standard deviation) was 57±18 years, and the mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 22.6±8.3. The variables independently associated with mortality were (i) conditions present at the beginning of mechanical ventilation, age (hazard ratio: 1.01; p<0.001); the APACHE II score (hazard ratio: 1.01; p<0.005); acute lung injury/acute respiratory distress syndrome (hazard ratio: 1.38; p=0.009), sepsis (hazard ratio: 1.33; p=0.003), chronic obstructive pulmonary disease (hazard ratio: 0.58; p=0.042), and pneumonia (hazard ratio: 0.78; p=0.013) as causes of mechanical ventilation; and renal (hazard ratio: 1.29; p=0.011) and neurological (hazard ratio: 1.25; p=0.024) failure, and (ii) conditions occurring during the course of mechanical ventilation, acute lung injuri/acute respiratory distress syndrome (hazard ratio: 1.31; p<0.010); sepsis (hazard ratio: 1.53; p<0.001); and renal (hazard ratio: 1.75; p<0.001), cardiovascular (hazard ratio: 1.32; p≤0.009), and hepatic (hazard ratio: 1.67; p≤0.001) failure.

CONCLUSIONS

This large cohort study provides a comprehensive profile of mechanical ventilation patients in South America. The mortality rate of patients who required mechanical ventilation was higher, which may have been related to the severity of illness of the patients admitted to our ICU. Risk factors for hospital mortality included conditions present at the start of mechanical ventilation conditions that occurred during mechanical support.

Application of Mechanical Ventilation Weaning Predictors After Elective Cardiac Surgery

OBJECTIVE

To test several weaning predictors as determinants of successful extubation after elective cardiac surgery.

METHODS

The study was conducted at a tertiary hospital with 100 adult patients undergoing elective cardiac surgery from September to December 2014. We recorded demographic, clinical and surgical data, plus the following predictive indexes: static compliance (Cstat), tidal volume (Vt), respiratory rate (f), f/ Vt ratio, arterial partial oxygen pressure to fraction of inspired oxygen ratio (PaO2/FiO2), and the integrative weaning index (IWI). Extubation was considered successful when there was no need for reintubation within 48 hours. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were used to evaluate each index.

RESULTS

The majority of the patients were male (60%), with mean age of 55.4±14.9 years and low risk of death (62%), according to InsCor. All of the patients were successfully extubated. Tobin Index presented the highest SE (0.99) and LR+ (0.99), followed by IWI (SE=0.98; LR+ =0.98). Other scores, such as SP, NPV and LR-were nullified due to lack of extubation failure.

CONCLUSION

All of the weaning predictors tested in this sample of patients submitted to elective cardiac surgery showed high sensitivity, highlighting f/Vt and IWI.

Inspiratory muscle training facilitates weaning from mechanical ventilation among patients in the intensive care unit: a systematic review

QUESTION

Does inspiratory muscle training improve inspiratory muscle strength in adults receiving mechanical ventilation? Does it improve the duration or success of weaning? Does it affect length of stay, reintubation, tracheostomy, survival, or the need for post-extubation non-invasive ventilation? Is it tolerable and does it cause adverse events?

DESIGN

Systematic review of randomised trials.

PARTICIPANTS

Adults receiving mechanical ventilation.

INTERVENTION

Inspiratory muscle training versus sham or no inspiratory muscle training.

OUTCOME MEASURES

Data were extracted regarding: inspiratory muscle strength and endurance; the rapid shallow breathing index; weaning success and duration; duration of mechanical ventilation; reintubation; tracheostomy; length of stay; use of non-invasive ventilation after extubation; survival; readmission; tolerability and adverse events.

RESULTS

Ten studies involving 394 participants were included. Heterogeneity within some meta-analyses was high. Random-effects meta-analyses showed that the training significantly improved maximal inspiratory pressure (MD 7 cmH2O, 95% CI 5 to 9), the rapid shallow breathing index (MD 15 breaths/min/l, 95% CI 8 to 23) and weaning success (RR 1.34, 95% CI 1.02 to 1.76). Although only assessed in individual studies, significant benefits were also reported for the time spent on non-invasive ventilation after weaning (MD 16 hours, 95% CI 13 to 18), length of stay in the intensive care unit (MD 4.5 days, 95% CI 3.6 to 5.4) and length of stay in hospital (MD 4.4 days, 95% CI 3.4 to 5.5). Weaning duration decreased in the subgroup of patients with known weaning difficulty. The other outcomes weren't significantly affected or weren't measured.

CONCLUSION

Inspiratory muscle training for selected patients in the intensive care unit facilitates weaning, with potential reductions in length of stay and the duration of non-invasive ventilatory support after extubation. The heterogeneity among the results suggests that the effects of inspiratory muscle training may vary; this perhaps depends on factors such as the components of usual care or the patient's characteristics.

Differences in clinical outcomes according to weaning classifications in medical intensive care units

Background

Although the weaning classification based on the difficulty and duration of the weaning process has been evaluated in the different type of intensive care units (ICUs), little is known about clinical outcomes and validity among the three groups in medical ICU. The objectives of this study were to evaluate the clinical relevance of weaning classification and its association with hospital mortality in a medical ICU with a protocol-based weaning program.

Methods

All consecutive patients admitted to the medical ICU and requiring mechanical ventilation (MV) for more than 24 hours were prospectively registered and screened for weaning readiness by a standardized weaning program between July 2010 and June 2013. Baseline characteristics and outcomes were compared across weaning classifications.

Results

During the study period, a total of 680 patients were weaned according to the standardized weaning protocol. Of these, 457 (67%) were classified as simple weaning, 136 (20%) as difficult weaning, and 87 (13%) as prolonged weaning. Ventilator-free days within 28 days decreased significantly from simple to difficult to prolonged weaning groups (P < 0.001, test for trends). In addition, reintubation within 48 hours after extubation (P < 0.001) and need for tracheostomy during the weaning process (P < 0.001) increased significantly across weaning groups. Finally, ICU (P < 0.001), post-ICU (P = 0.001), and hospital (P < 0.001) mortalities significantly increased across weaning groups. In a multiple logistic regression model, prolonged weaning but not difficult weaning was still independently associated with ICU (adjusted OR 8.265, 95% CI 3.484–19.605, P < 0.001), and post-ICU (adjusted OR 3.180, 95% CI 1.349–7.497, P = 0.005), and hospital (adjusted OR 5.528, 95% CI 2.801–10.910, P < 0.001) mortalities.

Conclusions

Weaning classification based on the difficulty and duration of the weaning process may provide prognostic information for mechanically ventilated patients who undergo the weaning process.

Discontinuous versus Continuous Weaning in Stroke Patients

Background: An increasing number of stroke patients have to be supported by mechanical ventilation in intensive care units (ICU), with a relevant proportion of them requiring gradual withdrawal from a respirator. To date, weaning studies have focused merely on mixed patient groups, COPD patients or patients after cardiac surgery. Therefore, the best weaning strategy for stroke patients remains to be determined. Methods: Here, we designed a prospective randomized controlled study comparing adaptive support ventilation (ASV), a continuous weaning strategy, with biphasic positive airway pressure (BIPAP) in combination with spontaneous breathing trials, a discontinuous technique, in the treatment of stroke patients. The primary endpoint was the duration of the weaning process. Results: Only the 40 (out of 54) patients failing in an initial spontaneous breathing trial (T-piece test) were included into the study; the failure proportion is considerably larger compared to previous studies. Eligible patients were pseudo-randomly assigned to one of the two weaning groups. Both groups did not differ regarding age, gender, and severity of stroke. The results showed that the median weaning duration was 10.7 days (±SD 7.0) in the discontinuous weaning group, and 8 days (±SD 4.5) in the continuous weaning group (p < 0.05). Conclusions: To the best of our knowledge, this is the first clinical study to show that continuous weaning is significantly more effective compared to discontinuous weaning in mechanically ventilated stroke patients. We suppose that the reason for the superiority of continuous weaning using ASV as well as the bad performance of our patients in the 2 h T-piece test is caused by the patients' compliance. Compared to patients on surgical and medical ICUs, neurological patients more often suffer from reduced vigilance, lack of adverse-effects reflexes, dysphagia, and cerebral dysfunction. Therefore, stroke patients may profit from a more gradual withdrawal of weaning.

Pressure support-ventilation versus spontaneous breathing with "T-Tube" for interrupting the ventilation after cardiac operations

Objective

To compare pressure-support ventilation with spontaneous breathing through a T-tube for interrupting invasive mechanical ventilation in patients undergoing cardiac surgery with cardiopulmonary bypass.

Methods

Adults of both genders were randomly allocated to 30 minutes of either pressure-support ventilation or spontaneous ventilation with "T-tube" before extubation. Manovacuometry, ventilometry and clinical evaluation were performed before the operation, immediately before and after extubation, 1h and 12h after extubation.

Results

Twenty-eight patients were studied. There were no deaths or pulmonary complications. The mean aortic clamping time in the pressure support ventilation group was 62 ± 35 minutes and 68 ± 36 minutes in the T-tube group (P=0.651). The mean cardiopulmonary bypass duration in the pressure-support ventilation group was 89 ± 44 minutes and 82 ± 42 minutes in the T-tube group (P=0.75). The mean Tobin index in the pressure support ventilation group was 51 ± 25 and 64.5 ± 23 in the T-tube group (P=0.153). The duration of intensive care unit stay for the pressure support ventilation group was 2.1 ± 0.36 days and 2.3 ± 0.61 days in the T-tube group (P=0.581). The atelectasis score in the T-tube group was 0.6 ± 0.8 and 0.5 ± 0.6 (P=0.979) in the pressure support ventilation group. The study groups did not differ significantly in manovacuometric and ventilometric parameters and hospital evolution.

Conclusion

The two trial methods evaluated for interruption of mechanical ventilation did not affect the postoperative course of patients who underwent cardiac operations with cardiopulmonary bypass.

Daytime Versus Nighttime Extubations

Purpose:

Despite studies regarding outcomes of day versus night medical care, consequences of nighttime extubations are unknown. It may be favorable to extubate patients off-hours, as soon as weaning parameters are met, since this could decrease complications and shorten length of stay (LOS). Conversely, nighttime extubation could be deleterious, as staffing varies during this time. We hypothesized that patients have similar reintubation rates, irrespective of extubation time.

Methods:

A retrospective cohort study performed at 2 hospitals within a tertiary academic medical center included all adult intensive care unit (ICU) patients extubated between July 01, 2009 and May 31, 2011. Those extubated due to withdrawal of support were excluded. The nighttime group included patients extubated between 7:00 pm and 6:59 am and the daytime group included patients extubated between 7:00 am and 6:59 pm.

Results:

Of 2240 extubated patients, 1555 were extubated during the day and 685 were extubated at night. Of these, 119 (7.7%) and 26 (3.8%), respectively, were reintubated in 24 hours with likelihood of reintubation significantly lower for nighttime than daytime after multivariable adjustment (odds ratio [OR] = 0.5, 95% confidence interval [CI] 0.3-0.9, P = .01), with a similar trend for reintubation within 72 hours (OR = 0.7, 95% CI = 0.5-1.0, P = .07). There was a trend toward decreased mortality for patients extubated at night (OR = 0.6, 95% CI = 0.3-1.0, P = .06). There was also a significantly lower LOS for patients extubated at night ( P = .002). In a confirmatory frequency-matched analysis, there was no significant difference in reintubation proportion or mortality, but LOS was significantly less in those extubated at night.

Conclusions:

Intensive care unit extubations at night did not have higher likelihood of reintubation, LOS, or mortality compared to those during the day. Since patients should be extubated as soon as they meet parameters in order to potentially decrease complications of mechanical ventilation, these data provide no support for delaying extubation until daytime.

Acute and chronic respiratory failure

Respiratory failure (RF) can be attributed to a plethora of neuromuscular diseases (NMDs) and manifests clinically in a multitude of overt or more subtle ways. The basic principles of pathophysiology, diagnosis and treatment of neurologic diseases and of RF apply concomitantly to this subset of patients. Various entities should be approached according to the latest evidence-based recommendations. Treatment follows the natural disease progression, from minimal respiratory assistance to mechanical ventilation (MV). A comprehensive treatment plan has to be formulated that takes into consideration the patient's wishes.

N-terminal prohormone B-type natriuretic peptide and weaning outcome in postoperative patients with pulmonary complications

Objective

To evaluate the relationship between plasma N-terminal prohormone B-type natriuretic peptide (NT-proBNP) and weaning outcomes, and the ability of NT-proBNP level to predict weaning success, in cancer patients with pulmonary complications undergoing noncardiac major surgeries.

Methods

Patients who were mechanically ventilated following postoperative respiratory failure were enrolled. NT-proBNP levels at the end of a 2-h spontaneous breathing trial were measured. Weaning was considered a success in patients who completed the trial and maintained spontaneous breathing following extubation for >48 h.

Results

Out of 29 patients, 22 patients weaned successfully but weaning failed in 7 patients. Plasma NT-proBNP was significantly higher in the weaning failure group than in the weaning success group. For predicting weaning success, the optimal NT-proBNP threshold value at the end of the spontaneous breathing trial was <448 ng/l (receiver operating characteristic analysis; sensitivity 68.18%, specificity 85.71%, positive predictive value 93.7% and negative predictive value 46.2%).

Conclusion

Measuring NT-proBNP at the end of a spontaneous breathing trial may assist in predicting weaning success, as a noninvasive, quantitative and repeatable indicator of cardiac stress in patients with postsurgical respiratory failure.

[Sedation and weaning in neurocritical care: can concepts from general critical care be applied?]

The translation of modern principles of sedation and weaning from mechanical ventilation from general intensive care to neurocritical care has to take into account specific aspects of brain-injured patients. These include interactions with intracranial hypertension, disturbed autoregulation, a higher frequency of seizures and an increased risk of delirium. The advantages of sedation protocols, scoring tools to steer sedation and analgesia and an individualized choice of drugs with emphasis on analgesia gain more interest and importance in neurocritical care as well, but have not been thoroughly investigated so far. When weaning neurological intensive care unit (ICU) patients from the ventilator and approaching extubation it has to be acknowledged that conventional ICU criteria for weaning and extubation can only have an orienting character and that dysphagia is much more frequent in these patients.

Inactivity-induced respiratory plasticity: protecting the drive to breathe in disorders that reduce respiratory neural activity

Multiple forms of plasticity are activated following reduced respiratory neural activity. For example, in ventilated rats, a central neural apnea elicits a rebound increase in phrenic and hypoglossal burst amplitude upon resumption of respiratory neural activity, forms of plasticity called inactivity-induced phrenic and hypoglossal motor facilitation (iPMF and iHMF), respectively. Here, we provide a conceptual framework for plasticity following reduced respiratory neural activity to guide future investigations. We review mechanisms giving rise to iPMF and iHMF, present new data suggesting that inactivity-induced plasticity is observed in inspiratory intercostals (iIMF) and point out gaps in our knowledge. We then survey conditions relevant to human health characterized by reduced respiratory neural activity and discuss evidence that inactivity-induced plasticity is elicited during these conditions. Understanding the physiological impact and circumstances in which inactivity-induced respiratory plasticity is elicited may yield novel insights into the treatment of disorders characterized by reductions in respiratory neural activity.