Early rise in central venous pressure during a spontaneous breathing trial: A promising test to identify patients at high risk of weaning failure?

Predictors of weaning failure in ventilated intensive care patients: a systematic evidence map

BACKGROUND

Ventilator weaning is of great importance for intensive care patients in order to avoid complications caused by prolonged ventilation. However, not all patients succeed in weaning immediately. Their spontaneous breathing may be insufficient, resulting in extubation failure and the subsequent need for reintubation. To identify patients at high risk for weaning failure, a variety of potential predictors has already been examined in individual studies and meta-analyses over the last decades. However, an overview of all the predictors investigated is missing.

AIM

To provide an overview of empirically investigated predictors for weaning failure.

METHODS

A systematic evidence map was developed. To this end, we conducted a systematic search in the Medline, Cochrane, and CINAHL databases in December 2023 and added a citation search and a manual search in June 2024. Studies on predictors for weaning failure in adults ventilated in the intensive care unit were included. Studies on children, outpatients, non-invasive ventilation, or explanatory factors of weaning failure were excluded. Two reviewers performed the screening and data extraction independently. Data synthesis followed an inductive approach in which the predictors were thematically analyzed, sorted, and clustered.

RESULTS

Of the 1388 records obtained, 140 studies were included in the analysis. The 112 prospective and 28 retrospective studies investigated a total of 145 predictors. These were assigned to the four central clusters 'Imaging procedures' (n = 22), 'Physiological parameters' (n = 61), 'Scores and indices' (n = 53), and 'Machine learning models' (n = 9). The most frequently investigated predictors are the rapid shallow breathing index, the diaphragm thickening fraction, the respiratory rate, the P/F ratio, and the diaphragm excursion.

CONCLUSION

Predictors for weaning failure are widely researched. To date, 145 predictors have been investigated with varying intensity in 140 studies that are in line with the current weaning definition. It is no longer just individual predictors that are investigated, but more comprehensive assessments, indices and machine learning models in the last decade. Future research should be conducted in line with international weaning definitions and further investigate poorly researched predictors. Registration, Protocol: https://doi.org/10.17605/OSF.IO/2KDYU.

Central venous pressure waveform analysis during sleep/rest: a novel approach to enhance intensive care unit post-extubation monitoring of extubation failure

This pilot study aimed to investigate the relation between cardio-respiratory parameters derived from Central Venous Pressure (CVP) waveform and Extubation Failure (EF) in mechanically ventilated ICU patients during post-extubation period. This study also proposes a new methodology for analysing these parameters during rest/sleep periods to try to improve the identification of EF. We conducted a prospective observational study, computing CVP-derived parameters including breathing effort, spectral analyses, and entropy in twenty critically ill patients post-extubation. The Dynamic Warping Index (DWi) was calculated from the respiratory component extracted from the CVP signal to identify rest/sleep states. The obtained parameters from EF patients and patients without EF were compared both during arbitrary periods and during reduced DWi (rest/sleep). We have analysed data from twenty patients of which nine experienced EF. Our findings may suggest significantly increased respiratory effort in EF patients compared to those successfully extubated. Our study also suggests the occurrence of significant change in the frequency dispersion of the cardiac signal component. We also identified a possible improvement in the differentiation between the two groups of patients when assessed during rest/sleep states. Although with caveats regarding the sample size, the results of this pilot study may suggest that CVP-derived cardio-respiratory parameters are valuable for monitoring respiratory failure during post-extubation, which could aid in managing non-invasive interventions and possibly reduce the incidence of EF. Our findings also indicate the possible importance of considering sleep/rest state when assessing cardio-respiratory parameters, which could enhance respiratory failure detection/monitoring.

Critical Care Ultrasound in Shock: A Comprehensive Review of Ultrasound Protocol for Hemodynamic Assessment in the Intensive Care Unit

Shock is a life-threatening condition that requires prompt recognition and treatment to prevent organ failure. In the intensive care unit, shock is a common presentation, and its management is challenging. Critical care ultrasound has emerged as a reliable and reproducible tool in diagnosing and classifying shock. This comprehensive review proposes an ultrasound-based protocol for the hemodynamic assessment of shock to guide its management in the ICU. The protocol classifies shock as either low or high cardiac index and differentiates obstructive, hypovolemic, cardiogenic, and distributive etiologies. In distributive shock, the protocol proposes a hemodynamic-based approach that considers the presence of dynamic obstruction, fluid responsiveness, fluid tolerance, and ventriculo-arterial coupling. The protocol gives value to quantitative measures based on critical care ultrasound to guide hemodynamic management. Using critical care ultrasound for a comprehensive hemodynamic assessment can help clinicians diagnose the etiology of shock and define the appropriate treatment while monitoring the response. The protocol's use in the ICU can facilitate prompt recognition, diagnosis, and management of shock, ultimately improving patient outcomes.

A Randomized Controlled Clinical Trial Investigating the Weaning Process From Mechanical Ventilation in Elderly Patients With Dementia

BACKGROUND

Limited data is available regarding the weaning techniques employed for mechanical ventilation (MV) in elderly patients with dementia in China.

OBJECTIVE

The primary objective of this study is to investigate diverse weaning methods in relation to the prognostic outcomes of elderly patients with dementia undergoing MV in the intensive care unit (ICU). Specifically, we seek to compare the prognosis, likelihood of successful withdrawal from MV, and the length of stay (LOS) in the ICU.

METHODS

The study was conducted as a randomized controlled trial, encompassing a group of 169 elderly patients aged ≥ 65 years with dementia who underwent MV. Three distinct weaning methods were used for MV cessation, namely, the tapering parameter, spontaneous breathing trial (SBT), and SmartCare (Dräger, Germany).

RESULTS

In the tapering parameter group, the LOS in the ICU was notably prolonged compared to both the SBT and SmartCare groups. However, no statistically significant differences were observed among the groups with respect to demographic characteristics, such as age and sex, as well as factors including the rationale for ICU admission, cause of MV, MV mode, oxygenation index, hemoglobin levels, albumin levels, ejection fraction, sedation and analgesia practices, tracheotomy, duration of MV, successful extubation, successful weaning, incidences of ventilator-associated pneumonia, and overall prognosis.

CONCLUSIONS

Both the SBT and SmartCare withdrawal methods demonstrated a reduction in the duration of MV and LOS in the ICU when compared to the tapering parameter method.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR1900028449.

Cardiopulmonary interactions during ventilator weaning

Weaning a critically-ill patient from the ventilator is a crucial step in global management. This manuscript details physiological changes induced by altered heart-lung interactions during the weaning process, illustrates the main mechanisms which could lead to weaning failure of cardiac origin, and discuss a tailored management based on the monitoring of changes in central hemodynamics during weaning. The transition from positive-pressure ventilation to spontaneous breathing results in abrupt hemodynamic and metabolic changes secondary to rapidly modified heart-lung interactions, sudden changes in cardiac loading conditions, and increased oxygen demand. These modifications may elicit an excessive burden on both the respiratory and cardiovascular systems, result in a rapid and marked increase of left ventricular filling pressure, and ultimately result in a weaning-induced pulmonary oedema (WIPO). The T-piece trial induces the greatest burden on respiratory and cardiocirculatory function when compared to spontaneous breathing trial using pressure support ventilation with positive or zero end-expiratory pressure. Since LV overload is the mainstay of WIPO, positive fluid balance and SBT-induced acute hypertension are the most frequently reported mechanisms of weaning failure of cardiac origin. Although the diagnosis of WIPO historically relied on an abrupt elevation of pulmonary artery occlusion pressure measured during right heart catheterization, it is nowadays commonly documented by echocardiography Doppler. This non-invasive approach is best suited for identifying high-risk patients, depicting the origin of WIPO, and tailoring individual management. Whether this strategy increases the success rate of weaning needs to be evaluated in a population at high risk of weaning failure of cardiac origin.

Diagnostic value of an increase in central venous pressure during SBT for prediction of weaning failure in mechanically ventilated patients: A cross-sectional study

Background

Timely and successful extubation is an essential step forward in clinical practice to minimize complications of mechanical ventilation and unsuccessful weaning processes. Thus, research into predictive factors of weaning outcome to optimize spontaneous breathing trial (SBT) precision before extubation is critical in intensive care practices. In this study, we aimed to investigate the predictive factors of the weaning outcome before and during SBT in mechanically ventilated patients.

Methods

In this cross-sectional study, 159 mechanically ventilated patients who were eligible for SBT were enrolled. Of these patients, 140 had successful extubation, whereas the remainder failed. Each patient's PaCO2 and PaO2 levels, respiratory rate (RR), SpO2, mean arterial pressure (MAP), heart rate (HR), and central venous pressure (CVP) values at the start of SBT, 3 min later, and at the end of SBT were measured. These values, along with the patients' clinical characteristics, were then investigated to determine if there was any correlation between these variables and the weaning outcome.

Results

Our analysis revealed that increase in CVP, independent of hemoglobin (Hb) concentration, PaO2, SpO2, duration of mechanical ventilation (MV), length of intensive care unit (ICU) stay, and SBT process, as well as underlying disease, was positively correlated with extubation/weaning failure. While age, gender, vital signs (MAP, RR, and HR), sequential organ failure assessment (SOFA), and acute physiology and chronic health evaluation (APACHE) scores had no significant correlation with patients' extubation outcomes.

Conclusion

According to our findings, integrating CVP assessment into SBT besides routine indices measurement and monitoring can be considered for the prediction of weaning outcome in critically ill mechanically ventilated patients.

The emerging concept of fluid tolerance: A position paper

Fluid resuscitation is a core component of emergency and critical care medicine. While the focus of clinicians has largely been on detecting patients who would respond to fluid therapy, relatively little work has been done on assessing patients' tolerance to this therapy. In this article we seek to review the concept of fluid tolerance, propose a working definition, and introduce relevant clinical signals by which physicians can assess fluid tolerance, hopefully becoming a starting point for further research.

Pooled Analysis of Central Venous Pressure and Brain Natriuretic Peptide Levels in Patients With Extubation Failure

Purpose: Cardiac insufficiency has been considered to be a common cause of extubation failure. Some studies have shown that central venous pressure (CVP) and brain natriuretic peptide (BNP) are able to predict extubation outcomes. Therefore, we conducted a pooled analysis to evaluate the potential of CVP and BNP levels as predictors of extubation outcomes, using a cohort of critically ill patients who were on mechanical ventilation (MV).

Methods: We searched three online electronic databases up to October 2021. All data were analyzed using Review Manager 5.4. For each study, the analysis was performed using standardized mean differences (SMD) with 95% confidence intervals (CI).

Results: The pooled analysis of seven studies on CVP levels and extubation outcomes showed that elevated CVP levels were significantly associated with extubation failure (SMD:0.47, 95% CI: 0. 43–0.51, p < 0.00001). This association also appeared before extubation (SMD:0.47, 95% CI: 0. 43–0.51, p < 0.00001), but it did not appear after extubation (SMD: 0.63, 95% CI: −0.05–1.31, p=0.07). Similarly, pooled analysis of eight studies on BNP levels and extubation outcomes showed that increased BNP levels are closely related to extubation failure (SMD:0.68, 95% CI: 0.49–0.86, p < 0.00001). This relationship also occurs before (SMD: 0.57, 95% CI: 0.35–0.79, p < 0.00001) and after (SMD: 0.91, 95% CI: 0.59–1.23, p < 0.00001) extubation.

Conclusions: This study showed that elevated CVP and BNP levels are associated with extubation failure in critically ill patients. However, BNP levels are more valuable than CVP levels in predicting extubation outcomes.

Effect of spontaneous breathing trial on extubation in patients with acute exacerbation of chronic obstructive pulmonary disease under mechanical ventilation

Objective

To evaluate how spontaneous breathing trial (SBT) affects successful extubation and prognosis in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients under mechanical ventilation.

Methods

AECOPD patients under invasive mechanical ventilation were recruited into the study and divided into the SBT and non-SBT groups. SBT patients received SBT for 60 min before extubation, while non-SBT patients that met weaning criteria were immediately extubated without SBT.

Results

A total of 64 patients were enrolled in analysis, including 32 in SBT group and 32 in non-SBT group. Patients in the two groups had similar baseline demographics and clinical characteristics (all parameters: p =  > 0.05). Four (12.5%) patients in the SBT group and 5 (15.6%) in the non-SBT group were reintubated in 48 h of extubation (p = 0.821). During the 28-day follow-up after extubation, 3 patients died, 1 (3.1%) in the SBT group and 2 (6.3%) in the non-SBT group (p = 0.554).

Conclusion

Our findings indicate that SBT did not affect extubation success, in-hospital mortality, and 28-day survival in AECOPD patients under mechanical ventilation.