Reducing Airway Occlusion Time Without Losing Accuracy to Predict Successful Mechanical Ventilator Liberation During the Measurement of the Timed Inspiratory Effort Index.

BACKGROUND: In 2013, a new predictor of successful mechanical ventilation liberation named timed inspiratory effort (TIE) index was devised with the normalization of the maximum inspiratory pressure (obtained within 60 s of unidirectional airway occlusion) with the time at which the value was reached. The aim of this study was to verify whether the presence of a sequence of a certain number of inspiratory effort values between 30-60 s > 1.0 cm H2O/s could predict weaning success in a performance comparable to the TIE index. METHODS: This was a retrospective observational study using 4 databases of previous studies on the TIE index. All patients receiving mechanical ventilation for ≤ 24 h were eligible. Liberation from mechanical ventilation-extubation decisions was made based on performance with spontaneous breathing trials. P < .05 was considered significant. The performance of the TIE index was evaluated by calculating the area under the receiver operating characteristics (AUROC) curve. RESULTS: From 349 eligible patients, 165 subjects were selected for analysis. The AUROC for the TIE index in the studied sample was 0.92 (95% CI 0.87-0.97, P < .001). A sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s was found in 51.5% of the subjects, with successful ventilatory liberation occurring in 95.3%. The highest specificity values belonged to the sequence of ≤ 4 and ≤ 5 inspiratory efforts > 1.0 cm H2O/s; the highest positive predictive value and positive likelihood ratio belonged to the sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s. The mean time that could have been spared if the procedure were interrupted after the first sequence of 4 inspiratory efforts > 1.0 cm H2O/s was 23 ± 3 s. CONCLUSIONS: The presence of a sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s during the TIE index measurement was a reliable predictor of weaning success, which could allow timely interruption of the procedure and entail a substantial reduction in airway occlusion time.

New integrated weaning indices from mechanical ventilation: A derivation-validation observational multicenter study.

Background: To develop ten new integrated weaning indices that can predict the weaning outcome better than the traditional indices. Methods: This retrospective-prospective derivation-validation observational multicenter clinical trial (Clinical Trial.Gov, NCT01779297), was conducted on 1,175 adult patients admitted at 9 academic affiliated intensive care units (ICUs; 4 surgical and 5 medical), from Jan 2013 to Dec 2018. All patients, intubated and mechanically ventilated for at least 24 h and ready for weaning were enrolled. The study had two phases: at first, the threshold values of each index that best discriminate between a successful and an unsuccessful weaning outcome was determined among 208 patients in the derivation group. In the second phase, the predictive performance of these values was prospectively tested in 967 patients in the validation group. In the prospective-validation set we used Bayes' theorem to assess the probability of each test in predicting weaning. Results: In the prospective validation group, sensitivity, specificity, diagnostic accuracy, positive and negative predictive values, and finally area under the receiver operator characteristic curves and standard errors for each index (ten formulae) were calculated. Statistical values of ten formulae for aforesaid variables were higher than 87% (0.87-0.99). Conclusion: The new indices can be used for hospitalized patients in intensive care settings for accurate prediction of the weaning outcome.

Inspiratory Muscle Training With an Electronic Resistive Loading Device Improves Prolonged Weaning Outcomes in a Randomized Controlled Trial.

OBJECTIVES: To test if the use of an inspiratory muscle training program with an electronic resistive loading device is associated with benefits as to muscle strength, weaning, and survival in the ICU. DESIGN: Prospective randomized controlled trial. SETTINGS: Study conducted at the ICU of a Navy's hospital, Rio de Janeiro, Brazil, from January 2016 to September 2018. PATIENTS: Tracheostomized patients (18-86 yr) on prolonged weaning. INTERVENTIONS: Participants were assigned to inspiratory muscle training (intervention group) or a traditional T-piece protocol (control group). In the inspiratory muscle training group, participants underwent training with an electronic inspiratory training device (POWERbreathe K-5; Technologies Ltd, Birmingham, United Kingdom). MEASUREMENTS AND MAIN RESULTS: Changes in respiratory muscle strength and rates of ICU survival and weaning success were compared between groups. Forty-eight participants in the inspiratory muscle training group and 53 ones in the control group were included in the final analysis. The inspiratory muscle training was associated with a substantially higher gain on muscle strength as assessed by the maximal inspiratory pressure (70.5 [51.0-82.5] vs -48.0 cm H2O [36.0-72.0 cm H2O]; p = 0.003) and the timed inspiratory effort index (1.56 [1.25-2.08] vs 0.99 cm H2O/s [0.65-1.71 cm H2O/s]; p = 0.001). Outcomes at the 60th day of ICU were significantly better in the intervention group regarding both survival (71.1% vs 48.9%; p = 0.030) and weaning success (74.8% vs 44.5%; p = 0.001). CONCLUSIONS: The use of an inspiratory muscle training program with an electronic resistive loading device was associated with substantial muscle strength gain and positive impacts in two very relevant clinical outcomes: the rates of ICU survival and successful weaning.

Involvement of Respiratory Muscles During the Timed Inspiratory Effort Index Measurement With Surface Electromyography.

BACKGROUND: Mechanical ventilation is a life-support therapy that can be associated with respiratory muscle dysfunction that may perturb the weaning process. The timed inspiratory effort (TIE) index is a recently proposed weaning index that has been reported to be effective in predicting successful weaning. We sought to analyze the respiratory muscle groups involved with the TIE index measurement utilizing the surface electromyography (sEMG). METHODS: We conducted a prospective observational study including 46 mechanically ventilated subjects. The variable analyzed with sEMG was the root mean square (RMS) for correlation with the degree of recruitment of motor units and strength. The data were obtained along the 60 s of the TIE index measurement and analyzed in each one of the 3 20-s intervals. Pooled and individual muscle RMS values were analyzed comparing success and failure groups. P < .05 was considered significant. RESULTS: The median (interquartile range) age of the participants was 80 (71-87) y. The pooled sEMG data showed that muscle strength increased over time, following the profile observed for maximum inspiratory pressure, irrespective of the analyzed group. However, in line with the findings regarding maximum inspiratory pressure, the RMS medians were statistically higher at every 20-s interval in the success group. Diaphragm strength increased over time, with values reaching statistically significant differences at the end of the observation period, but only in the success group. In addition, diaphragm strength was statistically higher during the whole test in the success group. Finally, there was a substantial increase in sternocleidomastoid strength over time after 40 s of observation, which was not observed in the scalene muscles. CONCLUSIONS: Subjects succeeding in a weaning trial had higher muscle strength, confirmed in the pooled and the individual sEMG analysis. A vigorous diaphragm with low fatigue potential seems essential for successful weaning; the sternocleidomastoid may also be of importance in this regard.

Insuflador-exsuflador mecânico versus manobra PEEP-ZEEP em pacientes em ventilação mecânica prolongada / Mechanical insufflator-exsufflator versus PEEP-ZEEP maneuver in patients on prolonged mechanical ventilation

Introdução: A presença da via aérea artificial, associada com a imobilidade no leito, resulta em um déficit na desobstrução das vias aéreas em pacientes sob ventilação mecânica (VM). Tal condição contribui para o desenvolvimento de quadros de hipoxemia e/ou infecções respiratórias, aumentando o trabalho respiratório e também as falhas de extubação. Objetivo: Comparar os efeitos da utilização do insuflador-exsuflador mecânico e da manobra PEEP-ZEEP em relação à mecânica respiratória em pacientes ventilados mecanicamente por tempo prolongado. Métodos: Ensaio clínico randomizado cruzado, incluindo pacientes em ventilação mecânica por mais de 10 dias. Os pacientes foram randomizados para receber a aplicação do insuflador-exsuflador mecânico e da manobra PEEP-ZEEP. Foram mensuradas complacência pulmonar, estática e dinâmica, e resistência pulmonar antes e após a aplicação de cada técnica. Resultados: Foram incluídos 22 pacientes. Na análise intragrupos observa-se aumento significativo na complacência dinâmica e complacência estática após a aplicação de ambas as técnicas. A resistência pulmonar variou significativamente apenas após a aplicação do insuflador-exsuflador mecânico. Não foram observadas diferenças significativas na análise intergrupos. Conclusão: O insuflador-exsuflador mecânico e a manobra de PEEP-ZEEP demonstraram ter efeito positivo tanto sobre a complacência estática quanto a dinâmica. Entretanto, a resistência pulmonar aumentou após a aplicação do insuflador-exsuflador mecânico. (AU)

Introduction: The presence of the artificial airway associated with immobility in the bed results in a deficit in the clearance of the airways in patients under mechanical ventilation (MV). This condition contributes to the development of hypoxemia and/or respiratory infections, increasing respiratory work and also extubation failures. Objective: To compare the effects of the use of mechanical insufflation-exsufflation and PEEP-ZEEP maneuver in relation to respiratory mechanics in patients on prolonged mechanical ventilation. Methods: Randomized cross-over trial, including patients on mechanical ventilation for more than 10 days. The patients were randomized to receive the application of mechanical insufflator-exsuflator and PEEP-ZEEP maneuver. Pulmonary compliance, static and dynamic, and pulmonary resistance were measured before and after the application of each technique. Results: 22 patients were included. In the intragroup analysis we observed a significant increase in the dynamic compliance and static compliance after the application of both techniques. Pulmonary resistance varied significantly only after application of the mechanical insufflation-exsufflation. No significant differences were observed in the inter-group analysis. Conclusion: The mechanical insufflator-exsuflator and the PEEP-ZEEP maneuver were shown to have a positive effect on both static and dynamic complacency. However, pulmonary resistance increased after the application of the mechanical insufflation-exsufflation.(AU)

Serial Weekly Measurements of the Timed Inspiratory Effort Index Can Predict Successful Prolonged Weaning.

BACKGROUND: Patients who require prolonged weaning from mechanical ventilation represent a major challenge in intensive care, and the timed inspiratory effort (TIE) index has been shown to be a clinically valuable tool to predict weaning success. OBJECTIVE: To evaluate whether weekly serial measurements of the TIE index can predict the success in prolonged weaning. METHODS: A prospective observational study in which the subjects who started the weaning process off mechanical ventilation underwent weekly measurements of the TIE index. The area under the receiver operating characteristic curve was used to evaluate the accuracy of the TIE index as a predictor of weaning success. A multivariate Cox regression model was developed to test the association of TIE index values of ≥1.0 cm H2O/s with a failure of weaning. RESULTS: Seventy subjects were selected. Their median (IQR) age was 72 (62-78) y, the median (IQR) duration of mechanical ventilation was 17.5 (14-28) d, and the median (IQR) APACHE II (Acute Physiology and Chronic Health Evaluation) II score was 28 (24-31). Thirty-five of the 70 subjects (50%) died, 22 of them after successful weaning. A total of 224 tests were performed over 56 d. The area under the receiver operating characteristic curve of the TIE index was 0.93. In the analysis of the probability of success during the follow-up (Kaplan-Meier method), a significant difference was obtained in favor of those with a TIE index of ≥ 1.0 cm H2O/s (53% vs 32%, P = .030). In the multivariate Cox regression analysis, values of the TIE index ≥ 1.0 cm H2O/s revealed an inverse, strong, and independent association with failure (hazard ratio 0.36, 95% CI 0.15-0.91; P = .030). The following variables were also found to have an independent but direct association with failure: age and length of time before weaning. CONCLUSIONS: When measured weekly, a TIE index of ≥1.0 cm H2O/s was a good predictor of success in subjects who required prolonged weaning in our hospital.

The timed inspiratory effort: a promising index of mechanical ventilation weaning for patients with neurologic or neuromuscular diseases.

BACKGROUND: The aim of this study was to evaluate the performance of the recently described timed inspiratory effort (TIE) index in comparison with 4 other previously reported indices as to the weaning outcome in patients with neurologic or neuromuscular disorders. METHODS: This observational prospective study included subjects undergoing weaning from mechanical ventilation. The performance of the indices was evaluated by calculation of the area under the receiver operating characteristic curves. The areas under the curve were compared using the Hanley and McNeil method. P values<.05 were considered significant. RESULTS: Seventy-two subjects (57±20 y old) were selected for the study. Forty-three subjects were weaned, and 21 died during the study period. The mean duration of mechanical ventilation was 22.3±19.4 d. The areas under the curve of 5 weaning predictors (TIE index, integrative weaning index, noninvasive tension-time index, maximum inspiratory pressure, and breathing frequency/tidal volume index) were significantly higher than those of the other indices. The TIE index had the largest area under the curve (0.96±0.02) in comparison with the integrative weaning index (0.82±0.05, P=.009), noninvasive tension-time index (0.80±0.05, P=.001), maximum inspiratory pressure (0.77±0.06, P=.001), and breathing frequency/tidal volume index (0.72±0.06, P=.001). CONCLUSIONS: In patients with neurologic or neuromuscular impairment, the TIE index had a better performance than the best weaning indices used in clinical practice.

Evaluation of a new index of mechanical ventilation weaning: the timed inspiratory effort.

PURPOSE: The performance of most indices used to predict ventilator weaning outcomes remains below expectation. The purpose of this study was to evaluate a new weaning index, the timed inspiratory effort (TIE) index, which is based on the maximal inspiratory pressure and the occlusion time required to reach it. METHODS: This observational prospective study included patients undergoing mechanical ventilation. Patients ready to be weaned had their TIE index and 6 previously reported indices recorded. The primary end point was the overall predictive performance of the studied weaning indices (area under the receiver operating characteristic curves [AUCs]). The secondary end points were sensitivity, specificity, positive predictive value, and negative predictive value. P values <.05 were considered significant. RESULTS: From the 128 initially screened patients, the 103 patients selected for the study included 45 women and 58 men (mean age 60.8 ± 19.8 years). In all, 60 patients were weaned, 43 were not weaned, and 32 died during the study period. Tracheotomy was necessary in 61 patients. The mean duration of mechanical ventilation was 17.5 ± 17.3 days. The AUC of 3 weaning predictors (the TIE index, the integrative weaning index, and the frequency-to-tidal volume [f/Vt] ratio index) was higher than the other indices. The TIE index had the largest AUC. CONCLUSION: The TIE index performed better than the best weaning indices used in clinical practice.

Comparison of maximal inspiratory pressure, tracheal airway occlusion pressure, and its ratio in the prediction of weaning outcome: impact of the use of a digital vacuometer and the unidirectional valve.

OBJECTIVE: To investigate the predictive value of the maximal inspiratory pressure obtained by a digital vacuometer using a unidirectional valve (P(ImaxUV)) as to weaning outcome, and to compare its performance with the respiratory drive using airway occlusion pressure at 0.1 second (P(0.1)), and P(0.1)/P(ImaxUV). METHODS: Patients on mechanical ventilation for > 24 hours who fulfilled the weaning criteria were prospectively enrolled. Measurements of P(ImaxUV) and P(0.1) were accomplished with a digital vacuometer with a unidirectional valve that allows only exhalation. Measured values were electronically recorded and stored on the digital vacuometer measurement device. Cutoff points for the used parameters were: absolute values of P(ImaxUV) > 30 cm H(2)O, P(0.1) < 2.3 cm H(2)O, and P(0.1)/P(ImaxUV) < 0.10. Receiver operating characteristic curves were calculated to compare the predictive values of the indexes. RESULTS: One hundred three subjects completed the test. The areas under the receiver operating characteristic curve were 0.79 ± 0.04, 0.65 ± 0.05, and 0.74 ± 0.04 for P(ImaxUV), P(0.1), and P(0.1)/P(ImaxUV), respectively. The area under the receiver operating characteristic curve for P(ImaxUV) was higher than for P(0.1) and P(0.1)/P(ImaxUV), but statistical significance was only found against P(0.1) (P = .007). CONCLUSIONS: Every studied index had only a modest performance regarding prediction of weaning outcome. Of note, P(ImaxUV) values obtained by digital technology using a unidirectional valve performed better than historically reported using a conventional techniques, surpassing P(0.1) and P(0.1)/P(ImaxUV) in this regard.

Evaluation of the inspiratory pressure using a digital vacuometer in mechanically ventilated patients: analysis of the time to achieve the inspiratory peak.

BACKGROUND: The measurement of the maximal inspiratory pressure (P(Imax)) is of great importance in choosing the time for the start of weaning. OBJECTIVE: To measure the inspiratory pressure in mechanically ventilated patients suitable for weaning to determine the point at which the P(Imax) is achieved within 60 seconds of observation, and analyze factors associated with P(Imax) values. METHODS: Measurement of P(Imax) was accomplished with a digital vacuometer with a unidirectional valve, which allows only exhalation (P(ImaxUV)). With this technique, values are registered and stored, remaining accessible whenever necessary. All patients were on mechanical ventilation, and met the criteria recommended by the American Thoracic Society/European Respiratory Society in 2007 to undergo weaning trial. RESULTS: Eighty-four from the 87 enrolled patients completed the test. No patients reached the P(ImaxUV) in the first 20 seconds of observation. P(ImaxUV) was achieved between 20.1 and 40 seconds in 12 patients (14.0%), and between 40.1 and 60 seconds in 72 cases (86.0%). In a multivariate analysis model in which age, sex, days of mechanical ventilation, APACHE score, and respiratory drive (measured as airway-occlusion pressure 0.1 s after the start of inspiratory flow [P(0.1)]) were included, only age (P = .006) and P(0.1) (P = .003) were significantly associated with the values of P(ImaxUV). CONCLUSIONS: Within an observation period of 60 seconds, the majority of patients reached the maximal inspiratory peak between 40.1 and 60 seconds. Older patients were found to have lower P(ImaxUV) values, whereas higher values for P(0.1) strongly correlated with higher P(ImaxUV) values. These findings are potentially useful to improve successful weaning prediction in the future, but further studies are needed to better clarify this issue.