End Of Spontaneous Breathing Trial Research Articles

Studying Hemodynamics during Weaning from Mechanical Ventilation among Critically ill Pediatric Patients

Abstract Background Among the multiple causes of weaning failure from mechanical ventilation, cardiovascular dysfunction is increasingly recognized as a quite frequent cause that can be treated successfully. Knowledge of the changes in the cardiopulmonary pathophysiology occurring during mechanical ventilation and its withdrawal is a prerequisite for early recognition of weaning failure of cardiovascular origin and optimal patient management. Aim of the Work Identification of hemodynamic and biomarkers changes during weaning process from mechanical ventilation and how these changes predict weaning success Methodology This cross sectional study was conducted on 50 children who were admitted to Pediatric Intensive Care Units and were mechanically ventilated and ready to be weaned according to weaning criteria. assessment of hemodynamic changes during weaning was done by tracing and comparing vital data, echocardiography parameters and levels of serum BNP and troponin in all patients during pressure support ventilation and at the end of spontaneous breathing trial (SBT) for identification of changes during weaning and risk factors for weaning failure. Results There was statistically significant increase in heart rate, cardiac index and E/A ratio at the end of SBTin all studied patients with lower cardiac index in patients who failed weaning, significant increase in TAPSE at the end of SBT with lower TAPSE in patients who failed weaning. Levels of BNP1 during pressure support were significantly higher in patients who failed weaning however levels of troponin didn’t show significant changes. Conclusion Transthoracic echocardiography can accurately detect changes in central hemodynamics induced by the SBT. It helps the attending physician to identify patients at high risk of weaning failure, when documenting a lower cardiac index, low TAPSE values.

Association between diastolic dysfunction and fluid balance in critically ill patients during weaning from mechanical ventilation

ObjectiveTo assess the role of diastolic dysfunction and fluid balance in weaning failure. DesignProspective, observational, single center. SettingIntensive care unit of a university hospital. PatientsAdult patients on mechanical ventilation for more than 48 h who underwent a spontaneous breathing trial (SBT). InterventionsEchocardiography was performed immediately before and at the end of SBT. Patients were classified into two groups according to weaning outcome. Main variable of interestWeaning failure. ResultsAmong 89 patients included, weaning failure occurred in 33 patients (37%). Isolated diastolic dysfunction at the end of the SBT was more frequent in the failure group (39.3% vs. 17.8%, p = 0.025). Average daily fluid balance from ICU admission until first SBT was less negative in patients who failed than in those who succeed in the weaning (−648 mL [−884 to -138] vs. −893 mL [−1284 to −501], p = 0.007). Average daily fluid balance from the first SBT until the ICU discharge was more negative in the weaning failure than in the success group (−973 mL [−1493 to −201] vs. −425 mL [−1065 to 12], p = 0.034). Cox regression analysis showed that diastolic dysfunction was not an independent factor related to weaning failure but needed the association of positive fluid balance and age. ConclusionsWeaning failure due to diastolic dysfunction is highly related to fluid balance, and the deleterious effect of fluid balance on diastolic function is associated with age The timing of fluid removal could play a key role in this scenario.

Comparing lung aeration and respiratory effort using two different spontaneous breathing trial: T-piece vs pressure support ventilation

ObjectiveTo assess the changes in lung aeration and respiratory effort generated by two different spontaneous breathing trial (SBT): T-piece (T-T) vs pressure support ventilation (PSV). DesignProspective, interventionist and randomized study. SettingIntensive Care Unit (ICU) of Hospital del Mar. ParticipantsForty-three ventilated patients for at least 24 h and considered eligible for an SBT were included in the study between October 2017 and March 2020. Interventions30-min SBT with T-piece (T-T group, 20 patients) or 8-cmH2O PSV and 5-cmH2O positive end expiratory pressure (PSV group, 23 patients). Main variables of interestDemographics, clinical data, physiological variables, lung aeration evaluated with electrical impedance tomography (EIT) and lung ultrasound (LUS), and respiratory effort using diaphragmatic ultrasonography (DU) were collected at different timepoints: basal (BSL), end of SBT (EoSBT) and one hour after extubation (OTE). ResultsThere were a loss of aeration measured with EIT and LUS in the different study timepoints, without statistical differences from BSL to OTE, between T-T and PSV [LUS: 3 (1, 5.5) AU vs 2 (1, 3) AU; p = 0.088; EELI: −2516.41 (−5871.88, 1090.46) AU vs −1992.4 (−3458.76, −5.07) AU; p = 0.918]. Percentage of variation between BSL and OTE, was greater when LUS was used compared to EIT (68.1% vs 4.9%, p ≤ 0.001). Diaphragmatic excursion trend to decrease coinciding with a loss of aeration during extubation. ConclusionT-T and PSV as different SBT strategies in ventilated patients do not show differences in aeration loss, nor estimated respiratory effort or tidal volume measured by EIT, LUS and DU.

Rate of Change of Rapid Shallow Breathing Index and Extubation Outcome in Mechanically Ventilated Patients.

Rapid shallow breathing index (RSBI) has been widely used as a predictor of extubation outcome in mechanically ventilated patients. We hypothesize that the rate of change of RSBI between the beginning and end of a 120-minute spontaneous breathing trial (SBT) could be a better predictor of extubation outcome than a single RSBI measured at the end of SBT in mechanically ventilated patients. Methodology. In this prospective observational study, we enrolled 193 patients who met the inclusion criteria, of whom 33 patients were unable to tolerate a 120-minute SBT and were excluded from the study. The study population consisted of 160 patients, categorized into three subgroups: patients with normal lung (no reported history of respiratory diseases), patients with airway disease, and patients with parenchymal disease who completed 120 minutes of SBT on low levels of pressure support ventilation. RSBI was obtained from the ventilator display at the 5th and the 120th minutes of SBT. The rate of change of RSBI (RSBI 5-120) was calculated as (RSBI 2-RSBI 1)/RSBI 1 × 100. Receiver-operating characteristic (ROC) curves were plotted for RSBI 5-120 and RSBI 120 in all patients and among the three subgroups (normal group, airway group, and parenchymal group) to compare the superiority of their best thresholds in predicting extubation failure. The RSBI 5-120 threshold for extubation failure in the entire patient group was 23% with an overall accuracy of 88% (AUC = 0.933, sensitivity = 91%, and specificity = 86%) and the threshold of RSBI 120 for extubation failure in the entire patient group was 70 breaths/min/L with an overall accuracy of 82% (AUC = 0.899, sensitivity = 85%, and specificity = 81%). In patients in the normal lung group, the threshold of RSBI 5-120 was 22%, with an overall accuracy of 89% (AUC = 0.892, sensitivity = 87.5%, and specificity = 90%), and the RSBI 120 threshold was 70 breaths/min/L, with an overall accuracy of 89% (AUC = 0.956, sensitivity = 88%, and specificity = 90%). The RSBI 5-120 threshold in patients with airway disease was 25% with an accuracy of 86% (AUC = 0.892, sensitivity = 85%, and specificity = 86%) and the threshold of RSBI 120 was 73 breaths/min/L with an accuracy of 83% (AUC = 0.874, sensitivity = 85%, and specificity = 82%). In patients in the parenchymal disease group, the threshold of RSBI 5-120 was 24%, with an accuracy of 90% (AUC = 0.966, sensitivity = 92%, and specificity = 89%) and RSBI 120 threshold was 71 breaths/min/L, which was 88% accurate (AUC = 0.893, sensitivity = 85%, and specificity = 89%). The rate of change of RSBI between the 5th and 120th minutes was moderately more accurate than the single value of RSBI measured at the 120th minute in predicting extubation outcome.

Association between microcirculation in spontaneous breathing trial and extubation success.

This study assessed the association between changes in sublingual microcirculation after a spontaneous breathing trial (SBT) and successful extubation. Sublingual microcirculation was assessed using an incident dark-field video microscope before and after each SBT and before extubation. Microcirculatory parameters before the SBT, at the end of the SBT, and before extubation were compared between the successful and failed extubation groups. Forty-seven patients were enrolled and analysed in this study (34 patients in the successful extubation group and 13 patients in the failed extubation group). At the end of the SBT, the weaning parameters did not differ between the two groups. However, the total small vessel density (21.2 [20.4-23.7] versus 24.9 [22.6-26.5] mm/mm2), perfused small vessel density (20.6 [18.5-21.8] versus 23.1 [20.9-25] mm/mm2), proportion of perfused small vessels (91 [87-96] versus 95 [93-98] %), and microvascular flow index (2.8 [2.7-2.9] versus 2.9 [2.9-3]) were significantly lower in the failed extubation group than in the successful extubation group. The weaning and microcirculatory parameters did not differ significantly between the two groups before the SBT. More patients are required to investigate the difference between baseline microcirculation before a successful SBT and the change in microcirculation at the end of the SBT between the successful and failed extubation groups. Better sublingual microcirculatory parameters at the end of SBT and before extubation are associated with successful extubation.

Association between diastolic dysfunction and fluid balance in critically ill patients during weaning from mechanical ventilation

ObjectiveTo assess the role of diastolic dysfunction and fluid balance in weaning failure. DesignProspective, observational, single center. SettingIntensive care unit of a university hospital. PatientsAdult patients on mechanical ventilation for more than 48 h who underwent a spontaneous breathing trial (SBT). InterventionsEchocardiography was performed immediately before and at the end of SBT. Patients were classified into two groups according to weaning outcome. Main variable of interestWeaning failure. ResultsAmong 89 patients included, weaning failure occurred in 33 patients (37%). Isolated diastolic dysfunction at the end of the SBT was more frequent in the failure group (39.3% vs. 17.8%, p = 0.025). Average daily fluid balance from ICU admission until first SBT was less negative in patients who failed than in those who succeed in the weaning (−648 mL [−884 to -138] vs. −893 mL [−1284 to −501], p = 0.007). Average daily fluid balance from the first SBT until the ICU discharge was more negative in the weaning failure than in the success group (−973 mL [−1493 to −201] vs. −425 mL [−1065 to 12], p = 0.034). Cox regression analysis showed that diastolic dysfunction was not an independent factor related to weaning failure but needed the association of positive fluid balance and age. ConclusionsWeaning failure due to diastolic dysfunction is highly related to fluid balance, and the deleterious effect of fluid balance on diastolic function is associated with age The timing of fluid removal could play a key role in this scenario.

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

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. 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. 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. 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.

Association between elevated brain natriuretic peptide levels and weaning failure: A systematic review and meta-analysis.

Cardiovascular dysfunction has been reported as an important mechanism of weaning failure, and recent data suggest that elevated brain natriuretic peptide (BNP) levels is associated with an increased risk of weaning failure. Therefore, we performed this meta-analysis to evaluate the correlation between elevated BNP levels and weaning failure in critically ill patients subject to mechanical ventilation. A systematic search in Cochrane Library, Embase, PubMed and Web of Science was performed up to September 25, 2019. Standard mean differences (SMD) and corresponding 95% confidence intervals (CIs) of the BNP levels were calculated for each study. Nine studies with a total number of 589 were included in the final meta-analysis. The results showed that elevated BNP levels were significantly associated with the risk of weaning failure (SMD: 0.76, 95% CI: 0.47 to 1.05, P<.00001). The finding was consistent with the BNP measured before (SMD: 0.68, 95% CI: 0.26 to 1.11, P=.002) or at the end of spontaneous breathing trial (SBT) (SMD: 0.85, 95% CI: 0.52 to 1.18, P<.00001). This meta-analysis showed that increased plasma BNP concentration was associated with weaning failure in ICU patients.

Influencing factors of weaning outcome of intensive care unit patients with planned extubation

To determine the risk factors of extubation failure and its effect on the prognosis of patients who had successfully passed a spontaneous breathing trial (SBT). The clinical data of patients with mechanical ventilation more than 24 hours who passed SBT admitted to department of intensive care unit (ICU) of First Hospital of Qinhuangdao from November 2018 to November 2019 were retrospectively analyzed. According to the outcome of weaning within 48 hours after weaning, patients were divided into weaning success group and weaning failure group. The baseline data, the presence of basic cardiopulmonary diseases, B-type natriuretic peptide (BNP), fluid balance, albumin and hemoglobin within 24 hours before weaning, the time of mechanical ventilation before weaning, rapid shallow breathing index (RSBI) during SBT, oxygenation index, cough peak flow at the end of SBT, and prognostic indicators were collected. The outcome of weaning was taken as the dependent variable, and the observation factors were taken as the independent variable for univariate analysis. The factors with statistical significance in univariate analysis were analyzed by binary Logistic regression to determine the influencing factors of weaning failure. Of the 204 patients, 167 (81.9%) were successfully weaned, and 37 (18.1%) failed. Compared with the weaning success group, the total duration of mechanical ventilation and the length of ICU stay in the weaning failure group were significantly longer [days: 13.0 (7.5, 23.5) vs. 5.0 (3.0, 8.0), 17.0 (12.5, 31.0) vs. 10.0 (6.0, 15.0), both P < 0.01], and the tracheotomy rate and mortality were significantly higher (32.4% vs. 0%, 51.4% vs. 0%, both P < 0.01). Univariate analysis showed that there were significant differences in age, proportion of patients with cardiopulmonary diseases, BNP and cough peak flow between weaning failure group and weaning success group [age (years old): 70.65±15.78 vs. 62.69±15.82, cardiopulmonary diseases: 62.2% vs. 24.6%, BNP (ng/L): 416.87 (32.70, 1 225.80) vs. 45.36 (10.00, 273.60), cough peak flow (L/min): 59.89±9.06 vs. 83.84±16.52, all P < 0.01]. However, there were no significant differences in gender, acute physiology and chronic health evaluation II (APACHE II) at admission, mechanical ventilation time before weaning, albumin, hemoglobin, oxygenation index, RSBI and fluid balance 24 hours before weaning between weaning failure group and weaning success group [male: 51.4% vs. 68.3%, APACHE II: 16.70±6.65 vs. 15.67±6.28, mechanical ventilation time before weaning (days): 6.0 (2.5, 11.0) vs. 5.0 (3.0, 8.0), albumin (g/L): 27.78±4.15 vs. 27.76±4.46, hemoglobin (g/L): 102.43±15.80 vs. 100.61±17.19, oxygenation index (mmHg, 1 mmHg = 0.133 kPa): 359.33±79.83 vs. 365.75±78.23, RSBI (times×L-1×min-1): 50.73±24.97 vs. 46.76±15.53, positive fluid balance: 70.3% vs. 69.5%, all P > 0.05]. The results of binary Logistic regression analysis showed that age ≥ 75 years old [odds ratio (OR) = 3.099, 95% confidence interval (95%CI) was 1.003-9.574, P = 0.049], presence of cardiopulmonary diseases (OR = 3.599, 95%CI was 1.126-11.498, P = 0.031), BNP within 24 hours before weaning (OR = 1.002, 95%CI was 1.000-1.003, P = 0.005) were the risk factors of extubation failure, while cough peak flow at the end of SBT was the protective factor (OR = 0.869, 95%CI was 0.823-0.917, P = 0.000). For patients who had successfully passed SBT, age ≥ 75 years old, the presence of cardiopulmonary diseases and an increased level of BNP within 24 hours were the risk factors of extubation failure. In addition, the higher the cough peak flow at the end of SBT, the lower the risk of weaning failure will be.

Peripheral perfusion index as a predictor of failed weaning from mechanical ventilation.

We hypothesized that impairment of peripheral perfusion index (PPI) during spontaneous breathing trial (SBT) might be predictive of weaning failure. We included 44 consecutive, adult, patients, who were scheduled for weaning after at least 48 h of invasive mechanical ventilation in this prospective observational study. Weaning failure was defined as failed SBT or reintubation within 48 h of extubation. PPI readings were obtained before initiation of the SBT, and every 5 min till the end of the SBT. PPI ratio was calculated at every time point as: PPI value/ baseline PPI. The primary outcome was the accuracy of PPI ratio at the end of the SBT in detecting failed weaning. Forty-three patients were available for the final analysis. Eighteen patients (42%) were considered failed weaning. PPI ratio was higher in patients with successful weaning compared to patients with failed weaning during the last 15 min of the SBT. PPI ratio at the end of SBT was higher in patients with successful weaning compared to patients with failed weaning. PPI ratio at the end of SBT had good predictive ability for weaning failure {area under receiver operating characteristic curve (95% confidence interval): 0.833(0.688–0.929), cutoff value ≤ 1.41}. The change in PPI during SBT is an independent predictor for re-intubation. PPI could be a useful tool for monitoring the patient response to SBT. Patients with successful weaning showed higher augmentation of PPI during the SBT compared to re-intubated patients. Failure of augmenting the PPI by 41% at the end of SBT could predict re-intubation with negative predictive value of 95%. Clinical trial identifier: NCT03974568. https://clinicaltrials.gov/ct2/show/NCT03974568?term=ahmed+hasanin&draw=3&rank=17

Predictive value of lung ultrasound score on weaning outcome in patients with intro-abdominal infection undergoing mechanical ventilation

To evaluate the value of lung ultrasound score (LUS) on predicting weaning outcome in patients with intro-abdominal infection (IAI) undergoing mechanical ventilation. Patients with IAI undergoing mechanical ventilation admitted to Research Institute of General Surgery of East War Zone Hospital and intensive care unit (ICU) of the First People's Hospital of Lianyungang from January to December in 2018 were included. The patients who satisfied weaning criteria were enrolled in the weaning process, which included spontaneous breathing trial (SBT) and extubation. They were divided into SBT success group and SBT failure group according to whether passed 120-minute SBT or not. LUS scores before and after SBT were compared between the two groups. The patients in the SBT success group were extubated, and they were divided into successful extubation group and failed extubation group for sub-group analysis according to whether re-intubation was needed in 48 hours after extubation. LUS score before extubation (at the end of SBT) and 48 hours after extubation (48 hours after extubation in the successful extubation group or before re-intubation in the failed extubation group) were compared. The receiver operating characteristic (ROC) curve was drawn to evaluate the predictive value of LUS score before SBT for SBT failure and LUS score before extubation for the failure. A total of 76 patients with IAI undergoing mechanical ventilation were included. Twenty-three patients had duration of mechanical ventilation less than 48 hours, severe chronic obstructive pulmonary disease (COPD), tracheotomy or automatic discharge were excluded, and 53 patients were enrolled. SBT was failed in 9 patients, and successfully performed in 44 patients, of whom 23 patients with successful extubation, and 21 with failed extubation. The LUS scores before and after SBT in the SBT failure group were significantly higher than those in the SBT success group (before SBT: 13.22±1.99 vs. 10.79±1.64, t = -3.911, P = 0.000; after SBT: 19.00±1.12 vs. 13.41±1.86, t = -8.665, P = 0.000). ROC curve analysis showed that the area under ROC curve (AUC) of LUS score before SBT for predicting SBT failure was 0.82 [95% confidence interval (95%CI) was 0.67-0.98, P = 0.002]. When the optimum cut-off value was 12.5, the sensitivity was 66.7%, and the specificity was 84.1%. Sub-group analysis showed that the LUS scores before and after extubation in the failed extubation group were significantly higher than those in the successful extubation group (before extubation: 14.19±1.60 vs. 12.69±1.81, t = -2.881, P = 0.006; after extubation: 16.42±1.59 vs. 12.78±1.54, t = -7.710, P = 0.000). ROC curve analysis showed that the AUC of LUS score before extubation for predicting the failure was 0.81 (95%CI was 0.69-0.92, P = 0.000). When the optimum cut-off value was 13.5, the sensitivity was 80.0%, and the specificity was 65.2%. LUS score can effectively predict SBT outcome, risk of re-intubation after extubation in patients with IAI undergoing mechanical ventilation.

Higher Work of Breathing at the End of Successful Spontaneous Breathing Trial Does Not Predict Extubation Failure

SESSION TITLE: Mechanical Ventilation & Respiratory Failure I SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM PURPOSE: Spontaneous breathing trial (SBT) is the gold standard process to assess readiness for extubation in mechanically ventilated patients. Approximately 15% of extubated patients require reintubation within 48 hours. We hypothesized that patients having higher work of breathing (WOB) at the end of successful SBT would have higher likelihood re-intubation. METHODS: We performed a prospective observational study to calculate the WOB at the end of first successful SBT using proportional assist ventilation (PAV) mode of ventilation in intubated medical intensive care unit patients. The ventilator used was Purtian Bennet 840 equipped with PAV+ software capable of showing WOB scale of 0.0 to 2.0 J/L in proportional assist ventilation (PAV) mode. WOB was further divided as: low WOB (0.0 to 0.3 J/L), normal WOB ( 0.3-0.7 J/L),high WOB (0.7-1.0 J/L) and very high WOB (1.2 to 2.0 J/L). At the end of successful SBT patient were switched over to PAV mode with 5 % of total WOB support provided by ventilator for 5 minutes and the data was collected. This data was not used for clinical management and patients were extubated based on judgement of the treating physician. Extubated patients were followed for 48 hours. Extubation failure was defined as the need for reintubation or the use of non-invasive positive pressure ventilation (NIPPV) for respiratory distress within 48 hours of extubation. RESULTS: Data from the first successful SBTs in 111 patients was analyzed. Only 67.5% (75/111) of patients were extubated on the same day of the first successful SBT. Overall rate of extubation failure was 11.7% (13/111, 8 patients needed re-intubation, 4 patients needed NIPPV and 1 patient needed NIPPV and was subsequently intubated). Three (23%) patients had high WOB and 0 (0%) patient had very high WOB in the failure group and 10 (16.4%) patients had high WOB and 3 (4.9%) patients had very high WOB in success group (p=0.86). CONCLUSIONS: Patient’s work of breathing at the end of successful SBT does not predict extubation failure. CLINICAL IMPLICATIONS: Higher WOB at the end of SBT is not associated with extubation failure. We need more research to figure out what measures we can add to SBT measurements to decrease the extubation failure. DISCLOSURE: The following authors have nothing to disclose: Prajan Subedi, Hala Karnib, Thomas Gilbert, Douglas Foreman, Mike Wagner, Daniel Keena No Product/Research Disclosure Information

Diaphragm thickening fraction as a predictor of successful weaning from mechanical ventilation in patients with chronic obstructive pulmonary disease

Objective To evaluate the predictive performance of diaphragm thickening fraction (DTF) assessed by ultrasound in the feasibility of weaning from mechanical ventilation in patients with chronic obstructive pulmonary disease (COPD). Methods Forty-three patients with COPD were enrolled for prospective study.All patients were ventilated mechanically for more than 48 hours and were expected to be weaned when they met clinical criteria in the intensive care unit from February 2015 to August 2015.Patients received a spontaneous breathing trial under pressure support for 1 h. At the end of spontaneous breathing trial, the right hemi-diaphragm was visualized in the zone of apposition using a 6-13 MHz linear ultrasound probe. Diaphragm thickness was recorded at end-inspiration(DTei) and end-expiration(DTee), and the DTF was calculated as percentage from the following formula: (DTei - DTee) / DTee. Also the rapid shallow breathing index (RSBI) was calculated. Patients meeting weaning criteria were extubated. Weaning successfully was defined as spontaneous breathing for >48 h without any form of ventilation support. Results Twenty-five patients were weaned successfully and failure of weaning was found in 18 patients. A significant differences in DTF(39.66±13.22)%vs.(23.84±8.85)%, P<0.05 and RSBI(62.74±26.05)vs.(98.89±35.44), P<0.05 were observed between patients with successful weaning and patients with failure. The sensitivity and specificity of DTF≥30 % for successful weaning were 84% and 83.88 %, respectively. The area under the receiver operating characteristic curve was 0.872(95 % CI: 0.759-0.985)for DTF. By comparison, when RSBI was ≤105, there was a sensitivity of 92 %, and a specificity of 38.89 % for determining successful weaning. The area under the receiver operating characteristic curve was 0.804(95 % CI: 0.669-0.940)for RSBI. Conclusions This study shows that in a cohort of COPD patients, the assessment of DTF using diaphragm ultrasound may be useful to predict success weaning or failure during spontaneous breathing trial. Key words: Ultrasound; Diaphragm; Chronic obstructive pulmonary disease; Mechanical ventilation; Weaning; Bedside; Critical ill; Predictive value

Brain natriuretic peptide as a predictor of weaning from mechanical ventilation in patients with respiratory illness

BackgroundCardiovascular dysfunction has been reported as an important mechanism of weaning failure. Brain natriuretic peptide (BNP) is a sensitive and specific marker for cardiovascular dysfunction. ObjectiveTo determine the value of BNP levels measured at initiation and end of a 2h spontaneous breathing trial (SBT) as a predictor of successful weaning of mechanical ventilation in patients with respiratory illness. Patients and methodsThirty consecutive patients ready for weaning were prospectively enrolled in this cross-sectional analytic study over a 6-month period. All patients had been on spontaneous mode of weaning for at least 2h. Tidal volume, respiratory rate, rapid shallow breathing index (RSBI), minute ventilation and PaO2/FiO2 were observed at initiation of SBT. BNP was measured at the initiation (BNP1) and at the end of SBT (BNP2). Weaning failure is defined as either the failure of SBT or the need for reintubation within 48h following extubation. ResultsOut of the 30 included patients, 14 (46.6%) patients had failed weaning. PaCO2 and BNP2 were significantly higher in the patients with failed weaning as compared to those with successful weaning (P=0.025, P=0.031 respectively). However, BNP1 levels were not statistically significant between the 2 groups (P=0.722). On multiple regression analysis, BNP% (percent change in the BNP level during the 2-h SBT) was the only predictor of weaning success. As compared to other weaning parameters, BNP%≤14.9 had the best sensitivity, specificity, positive and negative predictive value. ConclusionMeasuring the percentage change in the BNP level during a SBT may be a good predictor of weaning success from mechanical ventilation in respiratory patients.

Impact of nitroglycerin infusion on weaning off hypertensive mechanically ventilated chronic obstructive pulmonary disease patients

IntroductionMechanical ventilation (MV) weaning trial can be compared to a cardiac stress test where spontaneous ventilation is a form of an exercise and therefore hemodynamic compromise can occur during the weaning process in critically ill patients. The combined increase in arterial pressure and heart rate during unsuccessful weaning is quite suggestive of weaning failure of cardiac origin. Assessment and prediction of weaning failure from cardiac origin remain complicated in patients with chronic obstructive pulmonary disease (COPD). Recent data showed that COPD itself is a powerful independent risk factor for cardiovascular morbidity and mortality, suggesting that occult cardiac dysfunction could be frequent in patients with COPD. The immediate transition from positive pressure mechanical ventilation to spontaneous ventilation may generate significant cardiopulmonary alterations that are complex and mainly include the inspiratory fall in intrathoracic pressure, the increase in work of breathing, and the catecholamine discharge that occur during abrupt transfer from mechanical ventilation to spontaneous breathing. Therefore, it could be suggested that a treatment targeting the cardiovascular system decreasing the preload might help the heart to tolerate the critical period of weaning more effectively. MethodsThis study was carried on 60 adult male and female patients admitted to the Critical Care Medicine Departments in the Alexandria Main University Hospital and who fulfilled the diagnosis of acute exacerbation of COPD according to the Global initiative for chronic obstructive lung disease (GOLD) [1], and considered eligible for weaning after at least 24h of invasive mechanical ventilation exhibiting systemic arterial hypertension during the start of spontaneous breathing trial. 30 of them were adult patients and served as the study group (Group I), and the other 30 were age-matched adults who served as the control group (Group II). Each group was subjected to spontaneous breathing trial (SBT) using a T-piece receiving FiO2 the same as during mechanical ventilation. Control group underwent SBT alone while the nitroglycerin group underwent continuous nitroglycerin infusion started at the beginning of the SBT and titrated to maintain normal arterial systolic blood pressure that is; 120–139mmHg). Hemodynamic, oxygenation and respiratory measurements were performed on the start of SBT, and after a 2-h T-piece SBT. ResultsCompared to the start of SBT, systolic arterial blood pressure and mean arterial blood pressure decreased [from (Mean±SD) 150.33±14.26, 112.56±9.37mmHg to 134.33±11.04, 92.78±5.81mmHg, respectively] in the nitroglycerin group, while the opposite occurred in the control group as systolic arterial blood pressure and mean arterial blood pressure increased [from (Mean±SD) 144.67±13.58, 109.78±10.09mmHg to 158.0±19.43, 114.73±10.82mmHg, respectively]. Mixed central venous saturation (ScvO2) decreased significantly in the control group at the end of SBT [from (Mean±SD) 71.90±1.84 to 69.25±2.20%], while in the nitroglycerin group, ScvO2 did not change at the end in comparison to the start of SBT [from (Mean±SD) 71.63±1.75 to 71.12±1.65%]. Nitroglycerin infusion at the start of SBT enabled a successful weaning from mechanical ventilation in 90% of patients in comparison to a successful weaning from mechanical ventilation of only 63.3% in the control group. ConclusionsNitroglycerin infusion might facilitate the weaning off hypertensive COPD patients by alleviating the cardiovascular compromise occurring during liberation from MV.

Extravascular Lung Water, B-Type Natriuretic Peptide, and Blood Volume Contraction Enable Diagnosis of Weaning-Induced Pulmonary Edema*

We tested whether the changes in extravascular lung water indexed for ideal body weight could detect weaning-induced pulmonary edema. We also studied the diagnostic value of blood volume contraction indices and B-type natriuretic peptide variations. Prospective study. Twenty-one patients who failed a first spontaneous breathing trial. None. We performed a second 60-minute T-tube spontaneous breathing trial. Before and at the end of spontaneous breathing trial, we recorded pulmonary artery occlusion pressure, the extravascular lung water indexed for ideal body weight, plasma B-type natriuretic peptide level, hemoglobin, and plasma protein concentrations. Weaning-induced pulmonary edema was defined by the association of signs of clinical intolerance and a pulmonary artery occlusion pressure greater than or equal to 18 mm Hg at the end of spontaneous breathing trial. Because some patients performed several spontaneous breathing trial, a primary analysis included all spontaneous breathing trial and a secondary analysis included only the first spontaneous breathing trial of each patient. In primary analysis, 36 spontaneous breathing trials were analyzed, 21 spontaneous breathing trial with weaning-induced pulmonary edema and 15 without. During spontaneous breathing trial, extravascular lung water indexed for ideal body weight increased only in cases with weaning-induced pulmonary edema (25% ± 23%). Plasma protein concentration, hemoglobin concentration, and B-type natriuretic peptide also significantly increased only in cases with weaning-induced pulmonary edema (9% ± 3%, 9% ± 4%, 21% ± 23%, respectively). The areas under the receiver operating characteristics curves to detect weaning-induced pulmonary edema were 0.89 (95% CI, 0.78-0.99) for extravascular lung water indexed for ideal body weight, 0.97 (0.93-1.01) for spontaneous breathing trial-induced changes in plasma protein concentration, 0.96 (0.90-1.01) for changes in hemoglobin concentration, and 0.76 (0.60-0.93) for changes in B-type natriuretic peptide. An increase in extravascular lung water indexed for ideal body weight greater than or equal to 14% diagnosed weaning-induced pulmonary edema with a sensitivity of 67% (95% CI, 43-85%) and a specificity of 100% (95% CI, 78-100%). The secondary analysis confirmed these results. Spontaneous breathing trial-induced increases in extravascular lung water indexed for ideal body weight, plasma protein concentrations, hemoglobin concentration, and B-type natriuretic peptide are reliable alternatives to the pulmonary artery catheter for diagnosing weaning-induced pulmonary edema.

New insights into weaning from mechanical ventilation: left ventricular diastolic dysfunction is a key player

To investigate the diagnostic performance of Doppler echocardiography (DE) in predicting the outcome of weaning from mechanical ventilation in patients without overt cardiac disease. Fifty critical care noncardiac patients who fulfilled predetermined criteria for weaning underwent DE before and at the end of spontaneous breathing trial (pre-SBT/end-SBT, respectively). "Conventional" mitral inflow analysis and "advanced" DE parameters [tissue Doppler imaging (TDI)-derived mitral/tricuspid annular velocities and color M-mode Doppler velocity of propagation (V p)] were used to assess left ventricular (LV) diastolic function/filling pressures. Weaning was considered successful if patients had been extubated after successful SBT and sustained spontaneous breathing for more than 48 h. Twenty-eight patients (56%) failed weaning: 23 patients failed SBT and 5 required reintubation within 48 h. Weaning failure was associated with the degree of LV diastolic dysfunction at pre-SBT (P = 0.01). Patients who failed weaning presented evidence of increased LV filling pressures at pre-SBT, by demonstrating increased E/E m and E/V p ratios compared with patients with successful outcome (P ≤ 0.004); pre-SBT values of lateral E/E m greater than 7.8 and E/V p greater than 1.51 predicted weaning failure with an area under the curve, sensitivity (%), and specificity (%) of 0.86, 79, and 100, and 0.74, 75, and 73, respectively. Lateral E/E m was the only factor independently associated with weaning failure before SBT; OR (95% CI) 5.62 (1.17-26.96), P = 0.03. Our findings suggest that LV diastolic dysfunction is significantly associated with weaning outcome in critically ill patients with preserved LV systolic function. An E/E m ratio greater than 7.8 may identify patients at high risk of weaning failure.

B-type natriuretic peptides for prediction and diagnosis of weaning failure from cardiac origin

To evaluate and compare BNP and NT-proBNP concentrations to predict weaning failure from mechanical ventilation (MV) due to heart failure (HF) before a spontaneous breathing trial (SBT) and to identify HF as the cause of failure. Prospective, observational study in a university hospital. The sample included 100 patients on MV for over 48 h who underwent an SBT. Echocardiography and sampling for natriuretic peptides were performed immediately before and at the end of SBT. HF was diagnosed by pulmonary artery occlusion pressure >18 mm Hg or signs of elevated filling pressures in echocardiography. Thirty-two patients failed the SBT, 12 due to HF and 20 due to respiratory failure (RF). Before SBT, BNP and NT-proBNP were higher in patients failing due to HF than RF or in successfully weaned patients. Cut-off values using ROC curve analyses to predict HF were 263 ng/L for BNP (p < 0.001) and 1,343 ng/L for NT-proBNP (p = 0.08). BNP and NT-proBNP increased significantly during SBT in patients failing due to HF. Increases in BNP and NT-proBNP of 48 and 21 ng/L, respectively, showed a diagnostic accuracy for HF of 88.9 and 83.3% (p < 0.001). BNP performed better than NT-proBNP for HF prediction (p = 0.01) and diagnosis (p = 0.009). B-type natriuretic peptides, particularly BNP, can predict weaning failure due to HF before an SBT; increases in natriuretic peptides during SBT are diagnostic of HF as the cause of weaning failure. BNP performs better than NT-proBNP in prediction and diagnosis of HF.

Changes in B-type natriuretic peptide improve weaning outcome predicted by spontaneous breathing trial

Despite the use of spontaneous breathing trial (SBT), predicting weaning success remains a major clinical challenge. Because cardiovascular dysfunction could be a major underlying mechanism of weaning failure, we evaluated the role of the levels of B-type natriuretic peptide (BNP), a marker for cardiovascular function, in patients who passed a 2-hr SBT. Fifty-two patients recovering from acute respiratory failure were enrolled as the testing group to determine the predictive value of BNP. The predictive value of BNP was validated in a second independent cohort of 49 patients. Then, we combined both groups of patients to conduct the final analysis. In the testing group of 52 patients, 41 passed SBT and were extubated. Of these patients, 33 patients (80%) were extubated successfully (extubation success) while eight patients (20%) were reintubated within 48 hrs (extubation failure). There were no differences in the baseline BNP levels, but the extubation failure group had significantly greater increases in BNP at the end of SBT than the extubation success groups (32.7%, 25-75 percentile = 25.7%-50.8% vs. 0.69%, -8.8%-10.72%, p < .001). The area under the receiver operating characteristic curves for the BNP change was 0.93 and an increase of BNP <20% during SBT had the best combination of sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy for predicting extubation success (91%, 88%, 97%, 70%, and 91%). This threshold value of BNP change was then validated in an independent cohort. Combining BNP with SBT as extubation criteria increased the extubation success rate to 95% from 78% using SBT alone (p = .035). Measuring the percentage change in the BNP level during a SBT may help improve the predictive value of SBT on weaning outcome.