Ventilator Weaning In Patients Research Articles

Predictive Value of Diaphragm Muscle Ultrasound for Ventilator Weaning Outcomes After Cervical Spinal Cord Injury: A Retrospective Case Series.

Neuromuscular respiratory failure after cervical spinal cord injury (cSCI) can lead to dependence on an invasive mechanical ventilator. Ventilator-free breathing after cSCI is associated with improved morbidity, mortality, and quality of life. We investigated the use of diaphragm muscle ultrasound to predict ventilator weaning outcomes after cSCI. This is a retrospective case series conducted at a university-affiliated freestanding inpatient rehabilitation facility. We identified patients with cSCI who had a tracheostomy and were dependent on an invasive mechanical ventilator at the time of admission to inpatient rehabilitation. A diaphragm muscle ultrasound was performed, which included measurements of the thickness of the diaphragm and a calculation of the thickening ratio (TR), which reflects diaphragm muscle contraction. The primary outcome measure was the need for mechanical ventilation at time of discharge from the inpatient rehabilitation facility. Successful ventilator weaning was defined as either daytime or full 24-hour ventilator-free breathing. Of the 21 patients enrolled, 11 (52%) were able to wean successfully (partially or fully) from the ventilator. Of the ultrasound measurements that were taken, the TR was the optimal predictor for ventilator weaning outcomes. A threshold of TR ≥ 1.2 as the maximum hemidiaphragm measurement had a sensitivity of 1.0 and specificity of 0.90 for predicting ventilator weaning. Normal diaphragm contractility (TR ≥ 1.2) as determined by diaphragm muscle ultrasound is a strong positive predictor for successful ventilator weaning in patients with cSCI. Utilizing diaphragm ultrasound, rehabilitation physicians can set precision rehabilitation goals regarding ventilator weaning for inpatients with respiratory failure after cSCI, potentially improving both outcomes and quality of life.

The application value of diaphragm ultrasound in the weaning of ventilator for patients undergoing heart valve replacement

Objective: To explore the role of diaphragm ultrasound in guiding the successful weaning of ventilators in patients undergoing heart valve replacement. Methods: Prospectively selected 103 patients who received heart valve replacement in the Department of Cardiac Surgery, Fuwai Hospital of the Chinese Academy of Medical Sciences from December 2019 to February 2021 were selected, who have received mechanical ventilation for ≥48 h and have entered the pre-weaning spontaneous breathing test. The patients were divided into a successful weaning group (n=83) and failed weaning group (n=20) according to the patient's weaning result. Receiver operating characteristic (ROC) curve was used to evaluate the value of diaphragm thickening rate and diaphragmatic excursion to predict the result of ventilator weaning. Results: Among 83 patients in the successful weaning group, 52 were male patients and 31 were female patients, with an average age of (56.5±5.5) years; 20 patients in the failed weaning group included 12 male patients and 8 female patients, with an average The age is (57.3±6.2) years old.The left DTF, right DTF, left DE, and right DE of the patients in the successfully weaned group were (39.0±17.8)%, (57.7±1.2)%, (11.9±4.3) mm, (18.5±1.4) mm, respectively, which were higher than those in the weaning failure group (18.1±4.5)%, (19.9±2.3)%, (6.2±2.8) mm, (11.9±1.5) mm, respectively. And the differences were statistically significant (all P<0.05). ROC curve analysis showed that the best cut-off values, the sensitivity and the specificity for the thickening rate of the left diaphragms of patients with successful weaning were 61%, 90.46% and 87.83%, respectively; while the best cut-off values, the sensitivity and the specificity for the thickening rate of the right diaphragms of patients with successful weaning were 88%, 96.07% and 89.67%, respectively. The optimal cut-off values, the sensitivity and the specificity of mobility of the left right diaphragms of patients are 11.3 mm, 81.38% and 80.24%, respectively; while the optimal cut-off values, the sensitivity and the specificity of right diaphragms of patients were 12.7 mm, 87.23% and 85.56%, respectively. Conclusion: Diaphragm ultrasound can more accurately predict the outcome of ventilator weaning in patients undergoing heart valve replacement surgery, and it has good clinical application value.

Electrical Impedance Tomography Predicts Weaning Success in Adult Patients With Delayed Upper Abdominal Surgery: A Single-Center Retrospective Study.

Objective: To evaluate the predictive value of electrical impedance tomography (EIT) in patients with delayed ventilator withdrawal after upper abdominal surgery.Methods: We retrospectively analyzed data of patients who were ventilated >24 h after upper abdominal surgery between January 2018 and August 2019. The patients were divided into successful (group S) and failed (group F) weaning groups. EIT recordings were obtained at 0, 5, 15, and 30 min of spontaneous breathing trials (SBTs) with SBT at 0 min set as baseline. We assessed the change in delta end-expiratory lung impedance and tidal volume ratio (ΔEELI/VT) from baseline, the change in compliance change percentage variation (|Δ(CW-CL)|) from baseline, the standard deviation of regional ventilation delay index (RVDSD), and global inhomogeneity (GI) using generalized estimation equation analyses. Receiver operating characteristic curve analyses were performed to evaluate the predictive value of parameters indicating weaning success.Results: Among the 32 included patients, ventilation weaning was successful in 23 patients but failed in nine. Generalized estimation equation analysis showed that compared with group F, the ΔEELI/VT was lower, and the GI, RVDSD, and (|Δ(CW-CL)|) were higher in group S. For predicting withdrawal failure, the areas under the curve of the ΔEELI/VT, (|Δ(CW-CL)|), and the RVDSD were 0.819, 0.918, and 0.918, and 0.816, 0.884, and 0.918 at 15 and 30 min during the SBTs, respectively.Conclusion: The electrical impedance tomography may predict the success rate of ventilator weaning in patients with delayed ventilator withdrawal after upper abdominal surgery.

Phrenic Nerve Stimulator Placement via the Cervical Approach: Technique and Anatomic Considerations

Diaphragmatic pacing via phrenic nerve stimulation can help improve breathing and facilitate mechanical ventilation weaning in patients with respiratory failure secondary to brainstem injury, high cervical spinal cord injury, or congenital central hypoventilation. Devices can be placed utilizing several techniques; however, nuances regarding placement are not well published. To describe our experience with phrenic nerve stimulator placement via the cervical approach with a focus on surgical anatomy, variations, and technique. Placement of phrenic nerve stimulator via a cervical approach is described in detail. Successful placement of phrenic nerve stimulator without complication. The cervical approach for the placement of a phrenic nerve stimulator is a safe and effective option for patients. Detailed knowledge of anatomy and anatomic variations is required. Potential advantages and disadvantages are discussed.

THE ROLE OF TRACHEOTOMY IN WEANING FROM MECHANICAL VENTILATION IN PATIENTS WITH COVID-19

Objective: Significant numbers of COVID-19 patients require invasive mechanical ventilation support during their treatment. Prolonged mechanical ventilation causes a tracheotomy need in some of those patients. The study aimed to assess the possible benefits of tracheotomy in patients with COVID-19 and its effect on clinical outcomes. Material and Method: Six patients with COVID-19 who underwent an open tracheotomy in our institution were retrospectively reviewed. Its effect on the prognosis, the effectiveness of the safety precautions, and personnel protective equipment (PPE) utilization during the tracheotomy procedures was evaluated. Results: Mean intubation period before a tracheotomy was 21 days (range,14-28). All patients were male with a mean age of 62. Five of them died postoperatively. One patient was discharged and decannulated. None of the airway team members were infected after the procedures. Conclusion: Tracheotomy in COVID-19 patients is a safe procedure when appropriate PPE measures are taken. Our data do not support the contribution of tracheotomy to accelerating ventilator weaning in patients with COVID-19.

Tracheotomy in COVID-19 Patients: A Systematic Review and Meta-analysis of Weaning, Decannulation, and Survival.

A systematic review and meta-analysis was conducted to determine the cumulative incidences of decannulation and mechanical ventilation weaning in patients with coronavirus disease 2019 (COVID-19) who have undergone a tracheotomy. Weighted average mean times to tracheotomy, to decannulation, and to death were calculated from reported or approximated means. PubMed, SCOPUS, CINAHL, and the Cochrane library. Studies were screened by 3 investigators independently. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed. Studies including patients with COVID-19 who underwent a tracheotomy were identified. Studies without reported mechanical ventilation weaning or decannulation were excluded. Data were pooled using a random-effects model. After identifying 232 unique studies, 18 articles encompassing outcomes for 3234 patients were ultimately included for meta-analysis, with a weighted mean follow-up time of 28.6 ± 6.2 days after tracheotomy. Meta-analysis revealed that 55.0% of tracheotomized patients were weaned successfully from mechanical ventilation (95% CI, 47.4%-62.2%). Approximately 34.9% of patients were decannulated successfully, with a mean decannulation time of 18.6 ± 5.7 days after tracheotomy. The pooled mortality in tracheotomized patients with COVID-19 was 13.1%, with a mean time of death of 13.0 ± 4.0 days following tracheotomy. At the current state of the coronavirus pandemic, over half of patients who have required tracheotomies are being weaned off of mechanical ventilation. While 13.1% patients have died prior to decannulation, over a third of all tracheotomized patients with COVID-19 reported in the literature have undergone successful decannulation.

Procalcitonin kinetics to guide sequential invasive-noninvasive mechanical ventilation weaning in patients with acute exacerbation of chronic obstructive pulmonary disease and respiratory failure: procalcitonin’s adjunct role

ABSTRACT How to identify the optimum switch point of sequential invasive and noninvasive ventilation is the focus of clinical attention on the patients suffering from acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated by acute respiratory failure (ARF). This study aims to explore the clinical significance of taking the change rate of procalcitonin (PCT) as identifying the timing of weaning on the mechanical ventilation for the patients of AECOPD followed by ARF as a complication. There were altogether 140 patients of AECOPD complicated with ARF, who were randomly selected and divided into a study group and a control group respectively. A change rate of serum PCT level exceeding 50% was taken as the switch point selection of tracheal intubation removal for the patients of the study group, while the ‘pulmonary infection control (PIC) window’ was done for those in the control group. With CRP, IL-6, TNF-a, PaCO2, PaO2, and Lac having been detected before and after treatment to them all, clinical indexes were obtained and compared between these two groups. The CRP, TNF-a, and IL-6 levels of the patients in the study group after treatment (p < 0.05) were lower than those in the control group. There was no significant difference in PaCO2, PaO2, and Lac between these two groups before and after treatment (p > 0.05). Even so, some other indexes available for the study group of patients were found to be lower than those for the control group (p < 0.05) in the following aspects: duration of invasive ventilation support, total time of mechanical ventilation support, incidence rate of ventilator-associated pneumonia, 48-hour reintubation rate, incidence rate of upper gastrointestinal bleeding, hospitalization time of critical respiratory illness, total hospitalization time, RICU treatment cost, total treatment cost, and mortality. It is preferable to take the change rate of PCT level exceeding 50% as the switch point of weaning time in sequential mechanical ventilation rather than the PIC window. Abbreviations AECOPD: acute exacerbation of chronic obstructive pulmonary disease; ARF: acute respiratory failure; PCT: procalcitonin; PaO2: the oxygen partial pressure; PaCO2: the partial pressure of carbon dioxide; TNF-a: serum tumor necrosis factor-a; IL-6: interleukin-6; CRP: serum C-reactive protein; PIC window: pulmonary infection control window; RICU: respiration and intensive care unit

Use of the modified Glasgow Coma Scale score to guide sequential invasive-noninvasive mechanical ventilation weaning in patients with AECOPD and respiratory failure.

Sequential invasive-noninvasive ventilation (NIV) improves the outcomes of patients with respiratory failure caused by acute exacerbation of chronic obstructive pulmonary disease (AECOPD); however, there is no clear consensus on the optimal timing of the switch to sequential invasive-NIV in these patients. In the present study, a potential role for the modified Glasgow Coma Scale (GCS) score to guide sequential weaning was investigated. Patients with AECOPD and respiratory failure were prospectively recruited from three study centers (Wenling Hospital Affiliated to Wenzhou Medical University, the First Affiliated Hospital of Wenzhou Medical University and Changsha Central Hospital) between January 1st 2016 and December 31st 2018. Patients were randomly assigned to group A and B, with the switching point for sequential weaning strategy in the two groups being a modified GCS score ≥13 and 10 points, respectively. Each group included 240 patients. Baseline demographic characteristics were comparable in the two groups. The duration of invasive mechanical ventilation (IMV) in group A was significantly shorter than that in group B. However, there were no significant between-group differences with respect to the incidence of re-intubation, ventilator-associated pneumonia, in-hospital mortality or the length of hospital stay. Use of a modified GCS score ≥13 as the switching point for sequential invasive-NIV may help decrease the duration of IMV in patients with AECOPD and respiratory failure.

Motor and Sensory Function as a Predictor of Respiratory Function Associated With Ventilator Weaning After High Cervical Cord Injury.

Objective To analyze the respiratory function of high cervical cord injury according to ventilator dependence and to examine the correlations between diaphragm movement found on fluoroscopy and sensory and motor functions.MethodsA total of 67 patients with high cervical spinal cord injury (SCI), admitted to our hospital were enrolled in the study. One rehabilitation physician performed sensory and motor examinations on all patients while each patient was in the supine position on the American Spinal Injury Association (ASIA) standard. In addition, fluoroscopic diaphragm movement studies and bedside spirometry were performed.ResultsBedside spirometry and diaphragm fluoroscopic tests were analyzed according to ventilator dependence. Forced vital capacity and maximal inspiratory pressure were significantly higher in the ventilator weaned group. Natural breathing during the fluoroscopic diaphragm examinations and ventilator weaning showed statistical significance with the movement on the right, while deep breathing showed statistical significance with the movement on both sides. Deep breathing movement has correlation with the C5 key muscle. Diaphragm movement has correlation with right C3 and bilateral C4 sensory functions.ConclusionThe present expansion study showed that, through simple bedside physical examinations, rehabilitation physicians could relatively easily predict diaphragm movement and respiratory function recovery, which showed significance with ventilator weaning in patients with high cervical SCI.

Predictive value of left ventricular diastolic dysfunction on mechanical ventilation weaning

To investigate the predictive value of left ventricular diastolic function on mechanical ventilation weaning in patients with left ventricular ejection fraction (LVEF) > 0.50. A retrospective case control study was conducted. Sixty-five patients with LVEF > 0.50 undergoing mechanical ventilation for more than 48 hours admitted to surgery intensive care unit (ICU) of China-Japan Friendship Hospital from June 2014 to December 2016 were enrolled. The clinical data and parameters of echocardiography before spontaneous breathing trial (SBT) were collected. The possible relationship between left ventricular diastolic function and the results of weaning was analyzed according to analysis of blood flow filling parameters of mitral valve orifice. According to the grading standard of left ventricular diastolic function, the patients were divided into normal, mild (level 1) and moderate to severe (level 2-3) groups, and the outcomes of weaning were compared among the groups. Then patients were also divided into two groups of weaning successfully and weaning failure, and the clinical data and left ventricular diastolic function parameters of patients were compared between the two groups. The predictive value of left ventricular diastolic function on results of weaning was evaluated with receiver operating characteristic curve (ROC). Sixty-five patients were enrolled and 28 patients (43.1%) failed weaning, 22 patients failed the first SBT and 6 required reintubation within 48 hours, 31 of the patients presented normal left ventricular diastolic function, 9 of patients presented mild diastolic dysfunction, and 25 of them presented moderate to severe diastolic dysfunction. So with the gradual increase of the severity of diastolic dysfunction, the rate of weaning failure was gradually increased, which was 16.1%, 44.6% and 76.0% respectively (χ 2 = 20.240, P = 0.001). Patients who failed weaning presented evidence of increased left ventricular filling pressures at pre-SBT, by demonstrating decreased deceleration time of E (DTE, s: 180.4±5.1 vs. 196.8±4.0, t = 2.567, P = 0.013), increased left ventricular mitral valve diastolic early and late filling velocity ratio (E/A: 1.47±0.08 vs. 1.14±0.05, t = 3.827, P = 0.000), increased lateral, septal and averaged left ventricular mitral valve diastolic early velocity and maximal velocity of mitral annulus in early diastolic velocity ratio (E/Em: 10.26±0.52 vs. 7.28±0.41, t = 4.535, P = 0.000; 10.08±0.58 vs. 8.16±0.40, t = 2.797, P = 0.007; 10.17±0.48 vs. 7.72±0.35, t = 4.231, P = 0.000), and the rapid shallow breathing index (RSBI) was also increased significantly (61.7±3.6 vs. 50.6±2.7, t = 2.507, P = 0.015). It was shown by ROC curve analysis that the basic left ventricular diastolic function at pre-SBT had the diagnostic performance in predicting the outcome of weaning from mechanical ventilation, especially E/A and lateral E/Em. Pre-SBT values of E/A greater than 1.2 and lateral E/Em greater than 7.9 predicted weaning failure with an area under the ROC curve (AUC), sensitivity, and specificity of 0.81±0.06 and 0.85±0.06, 82.6% and 91.3%, 81.4% and 80.7%, respectively, and the AUC was higher than RSBI (0.70±0.07). The AUC of combination of E/A > 1.2 and lateral E/Em > 7.9 predicting weaning failure was 0.86±0.05 with a sensitivity of 78.3% and a specificity of 93.6%. The results suggest that left ventricular diastolic dysfunction is significantly associated with weaning outcome in critical patients with LVEF > 0.50. The combination of E/A ratio greater than 1.2 and E/Em ratio greater than 7.9 may identify patients at high risk of weaning failure.

Predictors of the therapeutic effect of sivelestat in patients with acute lung injury associated with systemic inflammatory response syndrome.

BackgroundSivelestat, a neutrophil elastase inhibitor, was previously approved in Japan for the treatment of acute lung injury associated with systemic inflammatory response syndrome. However, sivelestat produced inconsistent therapeutic benefits. This study aimed to identify factors predicting the therapeutic effects of sivelestat.MethodsWe enrolled 53 mechanically ventilated patients who received sivelestat. The patients were classified as effective (n = 28) if they were weaned from the ventilator within 28 days, or as ineffective groups (n = 25). Patient characteristics were compared between these groups and multivariate logistic regression analysis was used to identify predictive factors. A validation study was then conducted in sivelestat-free patients.ResultsA high red blood cell count and low hydrogen ion concentration were significantly associated with a higher ventilator weaning rate in patients receiving sivelestat. The validation study revealed that the hydrogen ion concentration value also significantly associated with ventilator weaning in patients who did not receive sivelestat.ConclusionsAlthough hydrogen ion concentration was inversely associated with the ventilator weaning rate, it did not predict sivelestat efficacy. This study indicated that acute lung injury patients with a high red blood cell count would derive the most benefit from sivelestat administration.

The importance of tracheostomy to the weaning success in patients with conscious disturbance in the respiratory care center

BackgroundWhen to extubate the endotracheal tube is controversial in patients with depressed mental status. The use of the Glasgow Coma Scale (GCS) with score 8 or above as a criterion for extubation by many investigators is questionable. MethodsA total of 133 consecutive patients (M/F: 86/47; age: 71 ± 17 years) admitted to the respiratory care center (RCC) of the hospital were enrolled. The effects of GCS score on the outcomes and weaning rate of the patients were evaluated. ResultsThe mortality rate was significantly higher in patients with a GCS score<7T or derived GCS (dGCS) score < 10 (p = 0.011). In patients with a low GCS score (GCS < 7T or dGCS score < 10), the rate of successful ventilator weaning in patients with tracheostomy was significantly higher than that in patients without tracheostomy (GCS and dGCS: 94.4% vs. 38.5%, p = 0.001). However, tracheostomy in patients with a high GCS (GCS score ≥ 7T or dGCS score ≥ 10) did not lead to a higher success rate of weaning. In multivariable analysis, tracheostomy was still an independent determinant of successful weaning in patients with low GCS. ConclusionTracheostomy increases the success rate of weaning in patients with low GCS, but not in patients with high GCS. Mental status graded by GCS did affect the outcomes in patients with conscious disturbance in the RCC. The low tracheostomy rate in patients with low GCS affected the rate of successful weaning, which might have contributed to the higher mortality rate in patients with low GCS in the RCC.

Outcome of Physical Therapy Intervention on Ventilator Weaning and Functional Status

Our study aimed to understand the characteristics of ventilator dependence in patients at a respiratory care center and the potential effects of physical therapy on ventilator weaning and patients' functional status. Prospective data collection consisted of the following: (1) demographic data, including name, gender, age, diagnosis, the Acute Physiology and Chronic Health Evaluation as a severity of the disease, modified Glasgow Coma Scale, mobility at the time of admission, and days of hospitalization; (2) Rapid shallow breathing index (RSBI) as a predictive indicator of ventilator weaning, including indicators of ventilator weaning were collected from the respiratory flow sheet; and (3) Barthel index. Between July 1 and December 31, 2007, 126 patients were admitted to the respiratory care center, and those who required mechanical ventilation for more than 14 days were enrolled. Fifty-five subjects received physical therapy. The RSBI in patients who received physical therapy was 75.7 +/- 37.9 before therapy and 80.0 +/- 48.5 afterwards, while the Barthel index increased from 0.8 +/- 1.4 to 1.9 +/- 2.5 (p < 0.05). The RSBI decreased as time of physical therapy lengthened, but not significantly (r = 0.12, p = 0.44). The success rate of ventilator weaning in patients receiving physical therapy intervention versus non-physical therapy intervention was 58.2% and 40.9%, respectively. The results indicated that lengthening the physical therapy intervention time enhanced the ventilator weaning success rate while mobility was not affected (r = -0.11, p = 0.41). Physical therapy may be offered to ventilator-dependent patients in line with their individual needs to improve or maintain basic mobility.

The impact of programmatic psychological nursing on the time length of ventilator weaning in myasthenia gravis patients with mechanical ventilation

Objective To investigate the impact of psychological nursing on time length of ventilator weaning in patients with myasthenia gravis (MG). Methods Forty-four MG patients with mechanical ventilation were enrolled to the testing group. In this group, the time of ventilator weaning was determined according to the results of basic status and blood gas analysis. Furthermore, the designed, targeted and individuated psychological care was conducted in this group at different phases. In the control group, only the programmatic method of ventilator weaning was used with the steps of CMV, SIMV, SPONT, intermittence and completely weaning. The time length of ventilator weaning and the length of stay were compared between two groups.Results The time length of weaning in testing group was 14 days comparing with 18 days in control group.Although there was no statistical significance ( P = 0.752), the time length of ventilator weaning in testing group was shorter than that in control group. The length of stay was longer in control group than that in testing group (P = 0.039). Conclusions The time length of ventilator weaning and length of stay could be shortened with the designed, targeted and individuated psychological care during different phases of ventilator weaning in patients with MG. Therefore, the nursing efficacy would be improved and the pains and economic burden of patients would be relieved. Key words: Psychological nursing; Myasthenia gravis; Mechanical ventilation

Noninvasive mechanical ventilation during the weaning process: facilitative, curative, or preventive?

To avoid the complications associated with endotracheal intubation, noninvasive positive-pressure ventilation (NPPV) has been proposed in the management of ventilator weaning in patients with acute respiratory failure (ARF) of various etiologies. Several studies have been performed to assess the benefit of NPPV in various weaning strategies, including permitting early extubation in patients who fail to meet standard extubation criteria (facilitation use), avoiding reintubation in patients who fail extubation (curative use), and preventing extubation failure in nonselected and selected patients (preventive use). NPPV has been successfully used in facilitating early extubation, particularly in patients with chronic obstructive pulmonary disease. In contrast, applying curative NPPV to treat postextubation ARF in nonselected populations may not be effective and could even be deleterious. Early use of NPPV was successful in preventing ARF after extubation, and decreased the need for reintubation in selected patients at risk of developing postextubation ARF. It is important that caregivers clearly differentiate among these application modalities of NPPV. The skills and expertise of both medical and nonmedical personnel are crucial predictive factors for the success of NPPV in the ventilator weaning process.

Profil ventilatoire et pression d'occlusion des insuffisants respiratories chroniques lors du sevrage de la ventilation artificielle

Mechanical ventilation weaning in patients with chronic respiratory insufficiency is a period whose outcome is difficult to predict. Ventilatory patterns and occlusion pressure evolution were studied in ten hypercapnic COPD patients in the course of 31 attempts at weaning. The following constants were measured : respiratory frequency (f), tidal volume (V t), minute ventilation (V̊ e), inspiratory and expiratory duration (t i, t e) mean inspiratory flow (V t/t i) and occlusion pressure during the first 0.1 second. These values were taken every 15 minutes for two hours, then every two hours for twelve hours, finally every twelve hours for three days. Three types of behaviour (A, B, C) were observed during weaning. Type A evolution (ten courses), was characterized by an exhaustion occurring in less than two hours with a drop in V̊ e (6.1 ± 0.8 l . min −1), V t (163 ± 9 ml), V t/t i (304 ± 25 ml . s −1), t i (0.56 ± 0.08 s), and P 0.1 (5 ± 3.2 cm H 2O). Type B evolution (eleven courses) was characterized by the same ultimate failure as in type A when reconnected to the respirator. However, at the second hour, these patients had satisfactory ventilatory values : V̊ e = 8.4 ± 0.7 l . min −1, V t = 428 ± 19 ml, V t/t i = 382 ± 27 ml . s −1, t i = 1.12 ± 0.06 s, P 0.1 = 8.9 ± 0.5 cm H 2O. Type C grouped the ten succesfull weanings characterized by a stabilization of the parameters : V̊ e = 8.5 ± 0.9 l . min −1, V t = 400 ± 17 ml, t i = 1.14 ± 0.04 s, V t/t i = 350 ± 30 ml . s −1, at two hours, thirty-six hours and three days. On the other hand, the P 0.1 rised initially up to 7.5 ± 0.7 cm H 2O, then stabilized after thirty-six hours (8.9 ± 0.9 cm H 2O) and finally decreased at the third day (7.1 ± 0.7 cm H 2O). The ventilatory failure at reconnection suggests a diaphragmatic fatigue which may be primitive or secondary to a disturbance of intrapulmonary air-flow distribution.