Successful Spontaneous Breathing Trial Research Articles

Holistic Ultrasound to Predict Extubation Failure in Clinical Practice.

A weaning trial can be considered a stress test of the cardiorespiratory system; it increases oxygen demand and thus warrants a higher cardiac index and elevated breathing effort. We hypothesized that the combination of easily performed ultrasound measurements of heart, lungs, and diaphragm would yield good diagnostic accuracy to predict extubation failure. Adult subjects ventilated for > 72 h with a successful spontaneous breathing trial were included. Ultrasound measurements of heart (left ventricular function), lungs (number of B-lines), and diaphragm thickening fraction were performed during a spontaneous breathing trial. The primary outcomes were sensitivity, specificity, and area under the receiver operating characteristic curve of a holistic ultrasound approach for extubation failure. Re-intubation within 48 h was considered extubation failure. Eighty-three subjects were included, of whom 15 (18%) were re-intubated within 48 h. The sensitivity and specificity of a holistic approach were 100% (78.2-100%) and 7.7% (2.5-17.1%), respectively, with an area under the receiver operating characteristic curve of 0.54. The sensitivity and specificity of diaphragm thickening fraction, using a cutoff value of < 30% for extubation failure were 86.7% (59.5-98.3%) and 25.4% (15.5-37.5%), respectively, with an area under the receiver operating characteristic curve of 0.61. In subjects ventilated for > 72 h who had a successful spontaneous breathing trial, holistic ultrasound was a weak predictor for extubation failure. (ClinicalTrials.gov registration NCT04196361).

Role of a successful spontaneous breathing trial in ventilator liberation in brain-injured patients.

Spontaneous breathing trials (SBTs) have been shown to improve outcomes in critically ill patients. However, in patients with brain injury, indications for intubation and mechanical ventilation are different from those of non-neurological patients, and the role of an SBT in patients with brain injury is less established. The aim of the present study was to compare key respiratory variables acquired during a successful SBT between patients with successful ventilator liberation versus failed ventilator liberation. In this prospective study, patients with brain injury (≥18 years of age), who completed a 30-min SBT, were enrolled. Airway pressure, flow, esophageal pressure, and diaphragm electrical activity (ΔEAdi) were recorded before (baseline) and during the SBT. Respiratory rate (RR), tidal volume, inspiratory muscle pressure (ΔPmus), ΔEAdi, and neuromechanical efficiency (ΔPmus/ΔEAdi) of the diaphragm were calculated breath by breath and compared between the liberation success and failure groups. Failed liberation was defined as the need for invasive ventilator assistance within 48 h after the SBT. In total, 46 patients (51.9±13.2 years, 67.4% male) completed the SBT. Seventeen (37%) patients failed ventilator liberation within 48 h. Another 11 patients required invasive ventilation within 7 days after completing the SBT. There were no differences in baseline characteristics between the success and failed groups. In-depth analysis showed similar changes in patterns and values of respiratory physiological parameters between the groups. In patients with brain injury, ventilator liberation failure was common after successful SBT. In-depth physiological analysis during the SBT did not provide data to predict successful liberation in these patients. The trial was registered at ClinicalTrials.gov (No. NCT02863237).

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

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. Is the reconnection to mechanical ventilation (MV) for 1h after a successful SBT able to reduce the risk of reintubation? Randomized clinical trial conducted in four ICUs between August 2018 and July 2019. Candidates for tracheal extubation who metall 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 1h (R1h). The primary outcome was reintubation within 48 h. 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 48h vs18.2%(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). 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. Brazilian Clinical Trials Registry; No.: RBR-3x8nxn; URL: www.ensaiosclinicos.gov.br.

Medical Research Council Scale Predicts Spontaneous Breathing Trial Failure and Difficult or Prolonged Weaning of Critically Ill Individuals.

Handgrip strength is an alternative measure to assess peripheral muscle strength and is correlated with the Medical Research Council (MRC) scale, with promising values for diagnosing ICU-acquired weakness (ICUAW). Because ICUAW has been associated with delayed weaning from mechanical ventilation, we hypothesized that ICUAW evaluated with both the MRC scale score and handgrip strength are associated with failure of a spontaneous breathing trial (SBT) and duration of mechanical ventilation weaning. We conducted a prospective observational study in 3 general ICUs with a total of 54 beds at 2 academic hospitals. Adult subjects with > 48 h of mechanical ventilation who were eligible for weaning were included in the study. In the evaluation before the first SBT, the MRC score (P < .001) and handgrip strength (P < .001) were significantly different between subjects extubated after a successful first SBT (simple weaning) and those extubated any time after a failed first SBT (difficult weaning). Only the MRC score discriminated between first SBT success or failure (P < .001); in multivariate analysis, the MRC score was significantly associated with first SBT failure (odds ratio 0.91, 95% CI 0.88-0.97, P < .001) and difficult weaning (odds ratio 0.91, 95% CI 0.87-0.96, P < .001). Handgrip strength exhibited good accuracy in identifying ICUAW. MRC score was independently associated with SBT failure and difficult or prolonged weaning.

Evaluation of the Perceived Barriers and Facilitators to Timely Extubation of Critically Ill Adults: An Interprofessional Survey.

Spontaneous breathing trials (SBTs) are an evidence-based way of identifying patients ready for mechanical ventilation (MV) liberation. Despite their effectiveness, global SBT performance rates remain suboptimal, and many patients who demonstrate the ability to breathe on their own remain on MV. The factors that influence clinicians' decision to discontinue MV following a successful SBT remain unclear. The aim of this study was to explore the underlying causes of extubation delays in the intensive care unit (ICU) from an interprofessional perspective. An exploratory, descriptive, cross-sectional design was used. An online survey was administered in December 2019 to clinicians practicing in three ICUs at a single medical center in the U.S. Survey questions focused on clinicians' perceptions of current MV liberation practices and perceived barriers or facilitators to timely extubation after a successful SBT. Of 425 eligible clinicians, 135 completed the survey (31.7% response rate). The majority of clinicians believed the current SBT and extubation process took too long (n=108; 80.0%) and that this delay negatively affected patient outcomes. While professional groups differed in their rankings of importance, factors perceived to contribute to extubation delays most commonly included SBT timing, low provider confidence levels in making extubation decisions, and patient-specific factors. Potential strategies to overcome these barriers included developing an automated extubation protocol, performing SBTs when the provider responsible for final extubation decisions is physically present, and decreasing clinician perception of reprimand or condemnation for failed extubations. The MV liberation process is complex and dependent on the decisions of various ICU professionals. Clinicians perceive a number of potentially modifiable provider- and organizational-level factors that cause extubation delays in everyday practice. Understanding and addressing these barriers is essential for improving ICU quality and patient outcomes. Future research should explore the effect of nurse and respiratory therapist-driven extubation protocols on MV liberation rates.

Initial setting of high-flow nasal oxygen post extubation based on mean inspiratory flow during a spontaneous breathing trial.

High flow nasal cannula (HFNC) is commonly used post-extubation in intensive care (ICU). Patients' comfort during HFNC is affected by flow rate. The study aims to describe the relationship between pre-extubation inspiratory flow requirements and the post-extubation flow rates on HFNC that maximises patient's comfort. This was an observational, retrospective study conducted in a university-affiliated ICU. We included patients extubated following successful spontaneous breathing trial (SBT). During the SBT we recorded variables including inspiratory flow. Patients who passed the SBT were extubated onto HFNC. HFNC was titrated from 20L/min and increased in steps of 10L/min, up to 60L/min. At each step, patient's level of comfort was assessed. Fraction of inspired oxygen was titrated to maintain oxygen saturation 92-97%. Nineteen participants were enrolled in the study. There was a significant positive correlation between mean inspiratory flow pre-extubation and the flow setting on HFNC which achieved the best comfort post-extubation (r2 0.88; p<0.001). Overall, greatest comfort was observed for HFNC flows between 30 and 40L/min but with individual variability. Measuring mean inspiratory flow during an SBT allows for individualised setting of HFNC flow rate immediately post-extubation and achieves the greatest comfort and interface tolerance.

Sigh in Patients With Acute Hypoxemic Respiratory Failure and ARDS: The PROTECTION Pilot Randomized Clinical Trial

BackgroundSigh is a cyclic brief recruitment maneuver: previous physiologic studies showed that its use could be an interesting addition to pressure support ventilation to improve lung elastance, decrease regional heterogeneity, and increase release of surfactant.Research QuestionIs the clinical application of sigh during pressure support ventilation (PSV) feasible?Study Design and MethodsWe conducted a multicenter noninferiority randomized clinical trial on adult intubated patients with acute hypoxemic respiratory failure or ARDS undergoing PSV. Patients were randomized to the no-sigh group and treated by PSV alone, or to the sigh group, treated by PSV plus sigh (increase in airway pressure to 30 cm H2O for 3 s once per minute) until day 28 or death or successful spontaneous breathing trial. The primary end point of the study was feasibility, assessed as noninferiority (5% tolerance) in the proportion of patients failing assisted ventilation. Secondary outcomes included safety, physiologic parameters in the first week from randomization, 28-day mortality, and ventilator-free days.ResultsTwo-hundred and fifty-eight patients (31% women; median age, 65 [54-75] years) were enrolled. In the sigh group, 23% of patients failed to remain on assisted ventilation vs 30% in the no-sigh group (absolute difference, –7%; 95% CI, –18% to 4%; P = .015 for noninferiority). Adverse events occurred in 12% vs 13% in the sigh vs no-sigh group (P = .852). Oxygenation was improved whereas tidal volume, respiratory rate, and corrected minute ventilation were lower over the first 7 days from randomization in the sigh vs no-sigh group. There was no significant difference in terms of mortality (16% vs 21%; P = .337) and ventilator-free days (22 [7-26] vs 22 [3-25] days; P = .300) for the sigh vs no-sigh group.InterpretationAmong hypoxemic intubated ICU patients, application of sigh was feasible and without increased risk.Trial RegistryClinicalTrials.gov; No.: NCT03201263; URL: www.clinicaltrials.gov

Central Venous-to-Arterial PCO2 Difference and Central Venous Oxygen Saturation in the Detection of Extubation Failure in Critically Ill Patients.

To evaluate the ability of central venous-to-arterial carbon dioxide pressure difference, central venous oxygen saturation, and the combination of these two parameters to detect extubation failure in critically ill patients. Multicentric, prospective, observational study. Three ICUs. All patients who received mechanical ventilation for more than 48 hours and tolerated spontaneous breathing trials with a T-piece for 60 minutes. Extubation after successful spontaneous breathing trials. Extubation failure was defined as the need for mechanical ventilation within 48 hours. The oxygen delivery index, oxygen consumption index, central venous oxygen saturation, central venous-to-arterial carbon dioxide pressure difference, and oxygen extraction were measured immediately before spontaneous breathing trials and at 60 minutes after spontaneous breathing trials initiation. Seventy-five patients were enrolled, and extubation failure was noted in 18 (24%) patients. Oxygen consumption index increased significantly during spontaneous breathing trials in the failure group. Oxygen delivery index increased in both success and failure groups. Oxygen extraction increased in the failure group (p = 0.005) and decreased in the success group (p = 0.001). Central venous oxygen saturation decreased in the failure group and increased in the success group (p = 0.014). ΔPCO2 value increased in the extubation failure group and decreased in the success group (p = 0.002). Changes in ΔPCO2 (Δ - ΔPCO2) and central venous oxygen saturation (ΔScvO2) during spontaneous breathing trials were independently associated with extubation failure (odds ratio, 1.02; 95% CI, 1.01-1.05; p = 0.006, and odds ratio, 0.84; 95% CI, 0.70-0.95; p = 0.02, respectively). Δ - ΔPCO2 and central venous oxygen saturation could predict extubation failure with areas under the curve of 0.865 and 0.856, respectively; however, their combined areas under the curve was better at 0.940. We found that Δ - ΔPCO2 and central venous oxygen saturation, during spontaneous breathing trials, were independent predictors of weaning outcomes. Combination analysis of both parameters enhanced their diagnostic performance and provided excellent predictability in extubation failure detection in critically ill patients.

Impact of Spontaneous Breathing Trials in Cardiorespiratory Stability of Preterm Infants.

A spontaneous breathing trial (SBT) is commonly used to determine extubation readiness in patients receiving mechanical ventilation. However, the physiological impact of such a trial in preterm infants has not been well described. This study aimed to investigate the effects of a 3-min SBT on the cardiorespiratory stability of these infants. A retrospective analysis of prospectively collected data was done for infants < 37 weeks gestational age who were extubated after a successful 3-min SBT. Heart rate, [Formula: see text], breathing frequency, exhaled tidal volume, and Silverman Andersen Respiratory Severity Score (SA-RSS) to assess work of breathing, before and at the end of the SBT, were recorded and compared using nonparametric paired Mann-Whitney tests. A secondary analysis was done between extubation success (ie, 72 h without the need for re-intubation) and failure groups. Differences were considered statistically significant if P < .05. A total of 90 SBTs were performed in 70 premature infants; 65 had a successful SBT, and 5 failed the SBT. Of the 65 infants who had a successful SBT and were extubated, 6 failed extubation (9.2%). Subjects had a median (interquartile range [IQR]) gestational age of 30 (27-33) weeks at birth, a birthweight of 1,240(860-1,790) g, and weight at extubation of 1,790(1,440-2,500) g. Cardiorespiratory stability was noted by a significant decrease in median (IQR) exhaled tidal volume (6.4 [4.9-8.4] mL/kg vs 5.2 (3.8-6.6] mL/kg, P < .001), a significant increase in mean ± SD breathing frequency (45.1 ± 11.4 vs 52.6 ± 14.4 breaths/min, P < .001), and a significant median (IQR) increase in work of breathing (SA-RSS of 1 [1-2] vs 2 [1-3], P < .001) at the end of the SBT. Respiratory instability was more remarkable in the success group. In preterm infants receiving prolonged mechanical ventilation, the performance of a 3-min SBT was associated with increased respiratory instability while still leading to a 10% extubation failure rate. Therefore, the routine use of SBTs to assess extubation readiness in this population is not recommended until there are clear standards and definitions, as well as good accuracy to identify failures.

Changes in energy expenditures while reducing pressure support as a predictor of successful spontaneous breathing trial

The objective: to assess changes in energy expenditures (EE) when reducing pressure support (PS) as a predictor of the patient’s readiness for transfer to spontaneous breathing. Subjects and methods. The study included 33 patients who had been on mechanical ventilation for at least 7 days. PS reduced from 20 to 4 cmH2O at the interval of 4 cmH2O. At each level, the patient's EE were measured with indirect calorimetry. At the end of the study, spontaneous breathing trial (SBT) was performed. Results. In 22 (67%) patients, at least one episode of a statistically significant increase in EE was observed upon transition to a lower level of PS (Group 1). In remaining 11 (33%) patients, with decreased level of PS, EE decreased or did not significantly change (Group 2). SBT was successful in 14 out of 22 patients from Group 1 and all 11 patients from Group 2. The absence of episodes of increased EE during decreased PS was a predictor of successful SBT (sensitivity – 44%, specificity – 100%). Conclusion. The absence of episodes of a statistically significant increase in EE during the transition to a lower level of PS is a highly specific predictor of successful SBT.

Value of Combination of Heart, Lung, and Diaphragm Ultrasound in Predicting Weaning Outcome of Mechanical Ventilation.

BackgroundPostextubation distress is detrimental to the prognosis of critically ill patients with successful spontaneous breathing trial. The known risk factors of failed weaning are associated with the heart, lungs, and diaphragm. The aim of this study was to explore the role of a combined model including indicators of heart, lung, and diaphragm ultrasound in predicting the weaning outcome.Material/MethodsPatients’ clinical data and ultrasonic features of heart, lungs, and diaphragm were recorded. Patients were included in either the failed weaning group (n=24) or the successful weaning group (n=81). The association of potential variables with the risk of weaning failure was determined using multivariate logistic regression analysis. The accuracy of potential indicators for predicting the weaning outcome were evaluated and a multiindicator combined model was established to improve the predictive accuracy.ResultsBrain natriuretic peptide (odds ratio [OR]=1.120, P=0.004), left-atrial pressure (LAP) (OR=1.333, P=0.005), lung ultrasound score (LUS) (OR=1.736, P=0.001), and hemidiaphragm dysfunction (OR=3.942, P=0.014) were associated with an increased risk of weaning failure. However, all of these indicators could not accurately predict the weaning outcome independently (all areas under the curve [AUCs] <0.9). The combination of LAP, LUS, and hemidiaphragm dysfunction showed the highest AUC (AUC=0.919).ConclusionsThe combined model including LAP, LUS, and hemidiaphragm dysfunction were the most accurate method for the prediction.

Brain natriuretic peptide to predict successful liberation from mechanical ventilation in critically ill patients: a systematic review and meta-analysis

BackgroundPredicting successful liberation from mechanical ventilation (MV) in critically ill patients is challenging. Brain natriuretic peptide (BNP) has been proposed to help guide decision-making for readiness to liberate from MV following a spontaneous breathing trial (SBT).MethodsWe performed a systematic review and meta-analysis of randomized and prospective observational studies that measured BNP levels at the time of SBT in patients receiving MV. The primary endpoint was successful liberation from MV (absence of reintubation or non-invasive ventilation at 48 h). Statistical analyses included bi-variate and Moses-Littenberg models and DerSimonian-Laird pooling of areas under ROC curve (AUROC).ResultsA total of 731 articles were screened. Eighteen adult and 2 pediatric studies were fulfilled pre-specified eligibility. The measure of the relative variation of BNP during SBT (ΔBNP%) after exclusion of SBT failure by clinical criteria in adults yielded a sensitivity and specificity of 0.889 [0.831–0.929] and 0.828 [0.730–0.896] for successful liberation from MV, respectively, with a pooled AUROC of 0.92 [0.88–0.97]. The pooled AUROC for any method of analysis for absolute variation of BNP (ΔBNP), pre-SBT BNP, and post-SBT BNP were 0.89 [0.83–0.95], 0.77 [0.63–0.91], and 0.85 [0.80–0.90], respectively.ConclusionThe relative change in BNP during a SBT has potential value as an incremental tool after successful SBT to predict successful liberation from MV in adults. There is insufficient data to support the use of BNP in children or as an alternate test to clinical indices of SBT, or the use of ΔBNP, BNP-pre, and BNP-post as an alternate or incremental test.Trial registrationPROSPERO CRD42018087474 (6 February 2018)

Influence of Arterial Blood Gas to Guide Extubation in Intensive Care Unit Patients after Spontaneous Breathing Trial.

Arterial blood gas is required for extubation decision after spontaneous breathing trial in most of intensive care unit. This study was conducted to assess the influence of arterial blood gas for extubation after successful spontaneous breathing trial in intensive care unit patients planned for extubation. It was prospective observation study conducted in all patients of age greater than eighteen year admitted in intensive care unit of tertiary care hospital for one year. It was done in 108 patients who were planned for extubation. Patients were assessed by intensivist clinically and decided whether a patient can be extubated on clinical grounds. Spontaneous breathing trial was done for 2 hours by t-piece in patients who met clinical and objective criteria. Arterial blood gas was done in all patients who successfully completed spontaneous breathing trial. Patients with successful spontaneous breathing trial, acceptable arterial blood gas were extubated. Independent Student's t test and paired t test was used for data analysis. Out of 108 patients who passed the spontaneous breathing trial, 96(88.88%) patients had acceptable arterial blood gas and were extubated and 12(11.11%) patients did not have acceptable arterial blood gas level and were chosen to have other mode of weaning. This study demonstrates that arterial blood gas level has changed decision for extubation after successful spontaneous breathing trial. Further, arterial blood gas might help in identification of patients who can undergo extubation failure when rapid shallow breathing index failed to predict outcome of extubation.

Prophylactic noninvasive positive pressure ventilation in the weaning of difficult-weaning tracheotomy patients.

BackgroundProphylactic noninvasive positive pressure ventilation (NPPV) reduces reintubation in endotracheal intubation patients. However, the efficacy of using the prophylactic NPPV in the weaning of tracheotomy patients is unclear.MethodsWe performed prophylactic NPPV in 11 tracheotomy patients who passed a spontaneous breathing trial (SBT), removed the tracheotomy tube, and closed the incision (intervention group). We matched another 11 tracheotomy patients who also passed an SBT but weaning and removing of tracheotomy tube were managed as conventional methods (control group).ResultsPatients in the control group had reinstitution of mechanical ventilation 36 times after the initial SBT success. Compared with the control group, the interventional group had fewer weaning days (3.0±2.1 vs. 11.3±9.2, P=0.01) from initial SBT success to successful weaning and shorter intensive care unit (ICU) length of stay (11.6±4.2 vs. 20.3±11.6, P=0.03) after initial SBT success. The interventional group had lower nosocomial pneumonia rates after initial SBT success (0/11 vs. 2/11), lower ICU mortality (0/11 vs. 2/11), lower hospital mortality (0/11 vs. 3/11), and higher successful weaning rate (11/11 vs. 8/11), but it didn’t reach significant difference. Also, there was no significant difference between groups in total duration of ventilation (25.5±13.3 vs. 34.7±24.2 days), hospital stay after initial SBT success (24.0±22.3 vs. 37.4±31.3 days), total ICU stay (35.7±15.3 vs. 45.0±29.5 days), and total hospital stay (48.7±33.1 vs. 68.6±52.6 days).ConclusionsProphylactic NPPV may be useful to accelerate weaning, and shorten ICU stay after initial SBT success in tracheotomy patients.

Factors associated with extubation failure in the intensive care unit patients after spontaneous breathing trial

Introduction: Extubation failure is associated with high mortality and poor outcome of patients. Aims: This study was conducted to assess the factors associated with extubation failure in the intensive care unit (ICU) patients planned for extubation. Settings and Design: It was a prospective observation study conducted in all patients aged >18 years admitted in the ICU of a tertiary care hospital. Subjects and Methods: It was done on 108 patients who were planned for extubation. Patients were assessed by an intensivist clinically and decided whether a patient can be extubated on clinical grounds. Spontaneous breathing trial (SBT) was done for 2 h by T-piece in patients who met clinical and objective criteria. Arterial blood gas (ABG) was done in all patients who successfully completed SBT. Patients with successful SBT and acceptable ABG were extubated. Patients were observed for 48 h for extubation failure, and the reason for reintubation was recorded. Statistical Analysis Used: Independent Student's t-test and Chi-square test were used for data analysis. Results: Of 108 patients who passed the SBT, 96 (88.88%) patients had acceptable ABG and were extubated. 85 (88%) underwent successful extubation and 11 (12%) underwent unsuccessful extubation. Duration of mechanical ventilation (MV) and chronic obstructive airway disease was a risk factor associated with extubation failure. Conclusion: Duration of MV of >2 days and chronic obstructive pulmonary disease were identified as independent risk factors for extubation failure.

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.

Influence of lung aeration on diaphragmatic contractility during a spontaneous breathing trial: an ultrasound study

BackgroundA spontaneous breathing trial (SBT) is a major diagnostic tool to predict successfully extubation in patients. Several factors may lead to weaning failure, including the degree of lung aeration loss and diaphragm dysfunction. The main objective was to compare the diaphragmatic contractility between patients with high lung aeration loss and low lung aeration loss during a 30-minute SBT by ultrasound.MethodsThis was a prospective single-center study. Lung ultrasound aeration score (LUS) and diaphragmatic thickening fraction (DTF) were measured during mechanical ventilation 1 h before SBT (T-1), 30 min (T1), and 120 min (T2) after the start of the SBT during quiet breathing. The right and left DTF were compared between patients with LUS ≥ 14 (high lung aeration loss), considered at high risk of post-extubation distress, and those with LUS < 14 (low lung aeration loss). The relationship between the LUS and DTF and the changes in LUS and DTF from T-1 to T2 in patients with LUS ≥ 14 were assessed.ResultsForty-nine patients were analyzed; 33 had LUS ≥ 14 and 16 had LUS < 14 at T1. The DTF at T1 was significantly higher in patients with LUS ≥ 14 than in those with LUS < 14: the right median (IQR) DTF was 22.2% (17.1 to 30.9%) vs. 14.8% (10.2 to 27.0%) (p = 0.035), and the left median (IQR) DTF was 25.0% (18.4 to 35.0%) vs. 18.6% (9.7 to 24.2%) (p = 0.017), respectively. There was a moderate positive correlation between the LUS and the DTF (Rho = 0.3, p = 0.014). A significant increase in the LUS was observed from T-1 to T1, whereas no change was found between T1 and T2. The DTF remained stable from T-1 to T2.ConclusionsDuring a SBT, diaphragmatic contraction acts differently depending on the degree of pulmonary aeration. In patients with high lung aeration loss, increased diaphragmatic contractility indicates an additional respiratory effort to compensate lung volume loss that would contribute to successful SBT. Further studies are needed to evaluate the combined evaluation of lung aeration and diaphragmatic function to predict the successful weaning of patients from mechanical ventilation.

Diaphragm dysfunction: weaning perspective

Weaning is the process of successfully liberating the patient from mechanical ventilation. The majority of patients will separate from the ventilator after a successful spontaneous breathing trial (SBT).1 In a minority of patients, weaning can be challenging and prolonged. Finding the cause of weaning difficulty is crucial to minimize the rates of extubation failure and prolonged ventilation.Diaphragm dysfunction (DD) has been described as a separate entity responsible for weaning failure with an incidence of 23–80%. It has also been associated with difficult weaning, prolonged intensive care unit (ICU) stay and mechanical ventilation, and increased ICU and hospital mortality.2 Sepsis, shock, and ventilator induced diaphragm dysfunction are important risk factors of DD. Diaphragm dysfunction has several mechanisms. Disuse atrophy and microstructural changes of the diaphragm have been described as the two cardinal pathophysiologic features.Establishing the diagnosis of DD can be complex in critically ill patients. Bilateral anterior magnetic phrenic stimulation is widely considered as the gold standard but is only available in large research centers with limited availability. Ultrasonography of the diaphragm is a promising tool given its wide availability, affordability, and non-invasive nature. Ultrasound is operator dependent, however and it does not provide continuous monitoring capabilities. The diaphragm thickening fraction (DTF) can be calculated from measuring the end-expiratory and end-inspiratory diaphragm thickness at the bedside. It correlates well with transdiaphragmatic pressure.3 Electromyography of the diaphragm may overcome the limitation of ultrasound by offering a continuous assessment of the diaphragmatic electrical activity, but it requires the placement of a specialized nasogastric tube.Management of DD is better approached by implementing a preventive and a curative strategy. From animal studies, allowing for spontaneous breathing on mechanical ventilation may prevent the problem. The degree of the recommended patient effort and ventilator assistance to achieve optimal balance between diaphragmatic loading and unloading are yet to be defined. Monitoring DTF while finding the optimal ventilator support level can be useful in this context. Another modality to prevent DD is diaphragm pacing applied through a transvenous phrenic nerve pacing system. Animal studies in pigs showed that this modality resulted in less diaphragm atrophy when pacing was synchronized with ventilation.4 There is an ongoing study to assess the role of diaphragm pacing to recondition and strengthen the diaphragm in difficult to wean mechanically ventilated patients (Clinicaltrials.gov NCT03107949).Once diaphragm dysfunction is established, no specific treatments exist at this time. Other causes of weaning failure like cardiac dysfunction have to be excluded and treated. Improving respiratory load and respiratory muscle weakness imbalance is also crucial. While it appears to improve inspiratory muscle strength parameters, inspiratory muscle training has not consistently shown improvements in weaning success.5 Levosemindan showed some benefit in improving diaphragm contractility and efficiency in healthy volunteers but was later found to increase likelihood of weaning failure in septic patients. Anabolic steroids were not found to be effective in treating diaphragm dysfunction in several studies. More evidence is needed before recommending non-invasive ventilation post-extubation in all DD patients.

KETAMINE IN THE ICU: TREATMENT OF POLYPHARMACY WITHDRAWAL SYNDROME

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: We present a case of severe polypharmacy withdrawal syndrome that was successfully treated with intravenous ketamine. CASE PRESENTATION: A 39-year-old male presented with aspiration pneumonia and hypoxic respiratory failure requiring mechanical ventilation for adult respiratory distress syndrome. He had a history of polysubstance abuse, bipolar disorder and severe anxiety, requiring psychiatric medications. High doses of propofol, midazolam, fentanyl, and dexmedetomidine were needed to control severe agitation while on the ventilator. There was substantial improvement in gas exchange and chest imaging to the extent that extubation was attempted following a successful spontaneous breathing trial. Soon after, the patient developed severe agitation with combative behavior and tachypnea that persisted despite sedative agents. The patient was reintubation followed by repeated attempts to adjust midazolam, propofol, fentanyl, and dexmedetomidine to levels that would control his agitation. A second extubation attempt was unsuccessful, and he required reintubation due to severe agitation, combative behavior as well as inability to control secretions. Intravenous ketamine was started - initial bolus 1 mg/kg followed by rapid titration to 2 mg/kg/hour to achieve coma. Fentanyl, propofol, midazolam, and dexmedetomidine were reduced and eventually discontinued completely. Ketamine was reduced until the patient was alert, calm, and cooperative followed by successful extubation. Ketamine was then tapered off, and the patient was transferred to the medical floors. DISCUSSION: We report the empiric use of ketamine to control severe agitation that was associated with successful extubation. Likely a history of polypharmacy recreational drug use combined with the need for very high dose of sedatives and opiates required for safe ventilatory support resulted in a severe withdrawal syndrome. Thus ketamine was chosen as a single agent to control delirium and combative behavior while discontinuing sedatives. Ketamine, an NMDA (N-Methyl-D-Aspartate) receptor antagonist in the central nervous system and spinal cord, is used as a sedative with dissociative and analgesic properties. This drug has several advantages: quick onset of action in thirty seconds of intravenous administration, short half-life, preservation of respiratory drive, and sympathomimetic effect that reduces risk of hypotension that is common with sedative agents. There are several reports its use in severe alcohol syndrome. Our case illustrates the potential benefit of ketamine to control polypharmacy withdrawal syndrome. CONCLUSIONS: This case shows that ketamine may have utility for control of severe agitation that is associated with withdrawal from high doses of sedatives and opiates required for the critically ill patient on mechanical ventilatory support with history of psychiatric illness and polysubstance drug use. Reference #1: Benken, S. T., & Goncharenko, A. (2016). The Future of Intensive Care Unit Sedation: A Report of Continuous Infusion Ketamine as an Alternative Sedative Agent. Journal of Pharmacy Practice, 30(5), 576-581. Reference #2: Malnoske, M. L, & Quill C (2017). Ketamine to facilitate weaning from mechanical ventilation: A case report. Journal of Anesthesia and Critical Care Case Reports, 3 (1), 11-13. Reference #3: Shah P, McDowell M, Ebisu R, Hanif T, Toerne T. Adjunctive Use of Ketamine for Benzodiazepine-Resistant Severe Alcohol Withdrawal: a Retrospective Evaluation. Journal of Medical Toxicology. 2018 Sep 1;14(3):229-36. DISCLOSURES: No relevant relationships by MORDECHAI GRABIE, source=Web Response No relevant relationships by Becky Lou, source=Web Response No relevant relationships by Paul Mayo, source=Web Response

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

IntroductionResearch supports the use of specific strategies to discontinue mechanical ventilation (MV) in critically ill patients. Little is known about how clinicians actually wean and discontinue MV in practice or...