Weaning Trial Research Articles

Long-Term Mechanical Ventilation: Management Strategies

This paper reviews management strategies for patients undergoing prolonged mechanical ventilation (PMV). Topics covered include how to identify and correct barriers to weaning, the systematic approach to weaning trials, when to cease weaning trials and proceed with life-long support, managing the tracheostomy tube during PMV, and, finally, how to select a suitable mechanical ventilator for PMV.

Impacto de um protocolo de desmame de ventilação mecânica na taxa de falha de extubação em pacientes de difícil desmame

To determine whether the predictive accuracy of clinical judgment alone can be improved by supplementing it with an objective weaning protocol as a decision support tool. This was a multicenter prospective cohort study carried out at three medical/surgical ICUs. The study involved all consecutive difficult-to-wean ICU patients (failure in the first spontaneous breathing trial [SBT]), on mechanical ventilation (MV) for more than 48 h, admitted between January of 2002 and December of 2005. The patients in the protocol group (PG) were extubated after a T-piece weaning trial and were compared with patients who were otherwise extubated (non-protocol group, NPG). The primary outcome measure was reintubation within 48 h after extubation. We included 731 patients-533 (72.9%) and 198 (27.1%) in the PG and NPG, respectively. The overall reintubation rate was 17.9%. The extubation success rates in the PG and NPG were 86.7% and 69.6%, respectively (p < 0.001). There were no significant differences between the groups in terms of age, gender, severity score, or pre-inclusion time on MV. However, COPD was more common in the NPG than in the PG (44.4% vs. 17.6%; p < 0.001), whereas sepsis and being a post-operative patient were more common in the PG (23.8% vs. 11.6% and 42.4% vs. 26.4%, respectively; p < 0.001 for both). The time on MV after the failure in the first SBT was higher in the PG than in the NPG (9 ± 5 days vs. 7 ± 2 days; p < 0.001). In this sample of difficult-to-wean patients, the use of a weaning protocol improved the decision-making process, decreasing the possibility of extubation failure.

Randomised weaning trial comparing assist control to pressure support ventilation

ObjectivesTo determine if the work of breathing was lower, respiratory muscle strength greater, but the degree of asynchrony higher during weaning by assist control ventilation (ACV) rather than pressure support...

Neuromuscular dysfunction associated with delayed weaning from mechanical ventilation in patients with respiratory failure

BackgroundMechanical ventilation offers essential ventilatory support, while the respiratory system recovers from acute respiratory failure. Yet, invasive mechanical ventilation is associated with risks and complications that prolong the duration of mechanical ventilation and increase the risk of death. Neuromuscular dysfunctions acquired during intensive care unit (ICU) stay are considered to be one of the important factors that impair the weaning process. The aim of this workTo evaluate the role of the neuromuscular factors responsible for difficult weaning from mechanical ventilation. MethodsThe study included 19 patients with difficult weaning from mechanical ventilation from the Alexandria medical respiratory intensive care unit (ICU) during the period from May 2009 till May 2010. The selected patients included patients who need mechanical ventilation for medical reasons, Patient fulfilling the parameters for weaning, (59) with failed spontaneous breathing trial. In the present study EMG and sensory–motor nerve conduction study was done. Results26% show normal study, 63% showed moderate to severe axonal sensory–motor peripheral neuropathy and 11% showed a picture of myopathy. The study revealed that 33% of the patients with peripheral neuropathy failed weaning trials and finally died. It is also found that drugs taken during ICU stay as corticosteroids and electrolyte disturbances (hypocalcaemia, hypophosphatemia, and hypomagnesaemia) may be related to the occurrence of neuromuscular dysfunctions. The present work also revealed a significant relationship between hypoalbuminemia and neuromuscular dysfunction. ConclusionsThe present study stresses on the importance of neuromuscular assessment in all cases with difficult weaning as this may be an important contributing factor for difficult weaning and prolonged mechanical ventilation (neuropathic or myopathic in origin). EMG and nerve conduction study may be of help for the detection of such disturbances. So, proper assessment of the neuromuscular apparatus and the management of any disorder may be a great step toward successful weaning.

The Relationship of 26 Clinical Factors to Weaning Outcome

The Burns Wean Assessment Program (BWAP) assessment checklist is designed to assist clinicians in the systematic evaluation of 26 clinical factors important to weaning. The authors recently described the relationship of the BWAP score (derived from the checklist) to weaning trial outcomes (weaning success or failure) in patients receiving mechanical ventilation for 3 days or longer in 5 adult critical care units. A BWAP score of 50 or higher was significantly associated with weaning success regardless of the specific category of patient (surgical, medical, cardiovascular, etc). This secondary analysis extends the evaluation of the BWAP checklist as it focuses on the importance of each individual BWAP factor to weaning outcomes in 5 different populations of patients. To identify the relative importance of the 26 BWAP factors to weaning success in patients undergoing mechanical ventilation for 3 days or longer in 5 adult critical care units. BWAP checklists were completed within 24 hours of a weaning attempt in surgical-trauma, medical, neurological, thoracic-cardiovascular, and coronary care units in a 5-year period. Advanced practice nurses using a multidisciplinary pathway, the BWAP checklist, protocols for weaning trials, and sedation guidelines managed the patients similarly. A total of 20 BWAP factors were significantly associated with successful weaning in all units combined (P ≤ .02). However, some differences in the importance of the BWAP factors to weaning outcome exist between units, with the neuroscience intensive care unit deviating the most from the other units. Although not all BWAP factors are significantly associated with weaning success, most are predictive. Restructuring the BWAP as a unit-specific weaning checklist and potential predictor may assist clinicians to address factors that may impede weaning more efficiently and effectively.

Spinal Cord Injury: Outcomes of Ventilatory Weaning and Extubation

Spinal cord injury (SCI) carries potentially devastating respiratory implications depending on injury level. Optimal strategies for mechanical ventilation in this setting remain poorly described. We reviewed our experience of ventilatory weaning and extubation outcomes in this patient population. Eighty mechanically ventilated SCI patients over a 5-year period at a major Level I trauma center were assessed. Injury, clinical, and outcome data were extracted using our ICU database, chart, and registry data. We identified 80 patients with SCI, classified by anatomic injury and motor functional level. There were no differences in injury severity between patients who were successfully extubated and those who failed (all p = NS). Seventy-four percent were extubated at the time of discharge; successful extubation was associated with lower level of cord injury (p = 0.001) and higher arrival Glasgow Coma Scale score (13.7 ± 2.6 vs. 10.8 ± 5.0, p = 0.021). Of extubation failures, 80% were due to pulmonary mechanical insufficiency, 22% inadequate pulmonary toilet, and 5% sedation or neurologic issues. Patients with weaning or extubation failures had longer ICU (29.9 days ± 24.5 days vs. 8.5 days ± 9.3 days; p < 0.001) and hospital stays (45.8 days ± 45.8 days vs. 26.6 days ± 23.9 days; p = 0.009), and higher rates of ventilator-associated pneumonia (83% vs. 15%, p < 0.001). Higher level of SCI correlates strongly with failure to wean and extubate; despite this, a subset of patients with high cord injury who can be safely weaned and extubated exists. A multicenter study is warranted to specifically identify patients with high SCI who merit weaning and extubation trials.

Weaning by gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) versus PS-supported SBT: A pilot study

Background and aim: Studies on weaning strategies have yielded conflicting results regarding the superiority of different methods. The aim of this RCT was to compare the efficacy of gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) with PS-supported SBT. MethodsPatients mechanically ventilated for >24h were randomized to weaning by gradual reduction of PS without an initial SBT versus once daily SBT (PS 7cm H2O). The primary outcomes were the rates of successful weaning trial and time to successful extubation. The secondary outcomes were the ICU and hospital length of stay, hospital mortality and the occurrence of ventilator-associated pneumonia (VAP). ResultsOf the 120 patients (61 males, median age 35 years), 58 were assigned to PS and 62 to the SBT group. The median (IQR) duration of ventilation prior to weaning was 80.2 (50.5---175.6) h. The baseline characteristics were similar in the two groups except the PaO2/FiO2 ratio, which was significantly higher in SBT group. The rates of successful weaning trial (89.7% versus 69.4%) were significantly higher in the PS group. The median duration of weaning (66h versus 81.5h, P = 0.05) and the median duration of ICU stay (8 days versus 9.4 days, P = 0.027) were lower in the PS group. There was no difference in hospital stay, mortality rates or occur-rence of VAP in the two arms. On multivariate analysis, the duration of ventilation prior to weaning, baseline SOFA score and the weaning method were predictors of successful extubation. ConclusionsGradual reduction of PS without an initial SBT was found to be associated with better outcomes compared to once daily PS-supported SBT.

Hot-topic debate on tolerance: Immunosuppression withdrawal

1. Liver allografts exhibit intrinsic tolerogenic properties that result in their spontaneous acceptance in many experimental animal models. 2. In clinical transplantation, liver allografts require milder immunosuppression regimens than other organs, are relatively resistant to antibody-mediated rejection, and only very rarely are lost because of immunological insults. 3. A fraction of stable liver transplant recipients can withdraw from all immunosuppression therapy and then maintain normal graft function and not experience rejection. This phenomenon is known as spontaneous operational tolerance (SOT). 4. The intentional discontinuation of immunosuppression in stable liver transplant recipients has led to successful weaning in almost 20% of recipients, but the true prevalence of SOT in unselected recipients is still unknown. 5. The prevalence could be higher in pediatric recipients undergoing transplantation before 1 year of age and in adult recipients with more than 10 years of posttransplant follow-up. 6. Rejection occurring during medically supervised immunosuppression weaning trials tends to be mild and, in the overwhelming majority of cases, can be easily resolved without the administration of high-dose immunosuppression. 7. Tolerant liver recipients exhibit specific transcriptional patterns in peripheral blood and liver tissue that may constitute future diagnostic markers of tolerance. 8. There is still no formal proof that the discontinuation of low-dose immunosuppression in long-term survivors of liver transplantation improves the morbidity and mortality rates associated with immunosuppression therapy.

Late onset congenital central hypoventilation syndrome after exposure to general anesthesia

Prolonged postoperative hypoventilation presents a challenge to anesthesiologists with regard to assessing etiology and related treatment. We present a case of recurrent episodes of postoperative hypoventilation in a previously asymptomatic child after uneventful general anesthesia. In this case, the child eventually required lifelong ventilatory support during sleep. A case of postoperative hypoventilation in a previously asymptomatic six-year-old child was investigated to determine the possible etiology. After uneventful general anesthesia for dental surgery, the child experienced recurrent episodes of hypoventilation associated with sleep. The child's lungs were mechanically ventilated due to failure of all trials of weaning. Clinical examination was unremarkable and laboratory investigations excluded the possibility of thyroid, hepatic, renal, and neuromuscular diseases. Computerized tomography, magnetic resonance imaging, and electroencephalogram studies were within normal limits. A negative pyridostigmine trial ruled out myasthenia. The child was finally diagnosed as having "late onset congenital central hypoventilation syndrome". Genetic testing revealed a PHOX2B mutation consistent with this diagnosis. The child was discharged home on mechanical ventilatory support during sleep. Congenital central hypoventilation syndrome is a rare lifelong multisystem disorder which may occur during the neonatal period as a result of severe genetic mutation in the PHOX2B gene. In mild mutations, a triggering factor, such as sedation or anesthesia, may be required for the syndrome to manifest itself. These patients often require lifelong mechanical ventilatory support, particularly during sleep.

Predictors of successful extracorporeal membrane oxygenation (ECMO) weaning after assistance for refractory cardiogenic shock

Detailed extracorporeal membrane oxygenation (ECMO) weaning strategies and specific predictors of ECMO weaning success are lacking. This study evaluated a weaning strategy following support for refractory cardiogenic shock to identify clinical, hemodynamic, and Doppler echocardiography parameters associated with successful ECMO removal. Hemodynamically stable patients underwent ECMO flow reduction trials to <1.5 L/min under clinical and Doppler echocardiography monitoring. When a patient had partially or fully recovered from severe cardiac dysfunction, tolerated the weaning trial, and had left ventricular ejection fraction (LVEF) >20-25% and aortic time-velocity integral (VTI) >10 cm under minimal ECMO support, device removal was considered. Among the 51 patients (34 males, aged 54 ± 14 years) who received ECMO for medical (n = 27), postcardiotomy (n = 11), or posttransplantation (n = 5) cardiogenic shock, 38 tolerated at least one ECMO flow reduction trial and 20 were ultimately weaned. Compared with the 13 patients who tolerated the trial but were not deemed weanable, those successfully weaned had, at each ECMO flow level, higher arterial systolic and pulse pressures, VTI, LVEF, and lateral mitral annulus peak systolic velocity (TDSa). All weaned patients had aortic VTI ≥10 cm, LVEF >20-25%, and TDSa ≥6 cm/s at minimal ECMO flow support. These Doppler echocardiography parameters better separated weaned and nonweaned patients than any other parameters tested. Patients who tolerated a full ECMO weaning trial and had aortic VTI ≥10 cm, LVEF >20-25%, and TDSa ≥6 cm/s at minimal ECMO flow were all successfully weaned. However, further studies are needed to validate these simple and easy-to-acquire Doppler echocardiography parameters as predictors of subsequent ECMO weaning success in patients recovering from severe cardiogenic shock.

An Uncommon Complication of Commonly Used Medication

Purpose: 73-year male was brought to ER with increasing yellowish discoloration of skin for 3 days; right upper quadrant (RUQ) abdominal pain and confusion for 1 day. Past medical history was significant for diabetes mellitus. The patient was in his usual state of health, when he was hospitalized with fever of 101 F, shortness of breath and cough approximately a week ago. After performing the laboratory work and chest x-ray, right lower lobe aspiration pneumonia was diagnosed and treated with intravenous clindamycin. Patient was discharged home on oral clindamycin on 3rd day. Four days post discharge patient started to notice yellowish discoloration of the eyes and face, gradually increasing in intensity over next 2-3 days and ultimately involving the whole body. On further questioning, the patient's family mentioned some RUQ discomfort with nausea, decreased appetite and increased confusion in the last 24 hours. His blood pressure was 98/63 mmHg, pulse 107 bts/min, respiration 22/min with oxygen saturation of 94% on room air and temperature of 99.5 F. On examination he exhibited grade II encephalopathy and profound jaundice. Abdominal exam was significant for tenderness in RUQ. The rest of the examination was unremarkable. Lab: white cell (WBC) of 11.5 Thou/mm3, with 80% neutrophils, liver function test (LFT) showed bilirubin of 6.9 with direct of 3.43 mg/dl, ALT 1076 IU/L, AST 440 IU/L, alkaline phosphatase 203 IU/L, ammonia 55 umol/L and INR was 2.1. His LFT's were normal prior to this visit. Ultrasound of the liver was reported as normal. Patient was admitted to ICU and clindamycin was held because of possible etiology behind the hepatic injury and it was switched to Zosyn® for broader coverage. Patient conditioned worsened and he developed acute respiratory distress syndrome, for which he was intubated. WBC continued to be elevated, in the face of negative sputum and blood culture, perhaps because of initial antibiotic therapy rendering the cultures negative. On 6th day his LFT's were ALT 437 IU/L, AST 205 IU/L, and bilirubin of 3.6 mg/dl. Serum ferritin, cerruloplasmin level, hepatic and antibody panel came back as normal. There was no history of alcohol use, Tylenol® or any other medication use that could be contributed to be the cause of hepatic failure. As patient continued to be mechanical ventilation dependent and failed multiple weaning trials, support was withdrawn according to his wishes. To conclude, our patient developed liver failure after being treated with clindamycin. Disordered LFT's and synthetic function, which improved after removing the offending agent, would support the diagnosis of clindamycin induced liver toxicity.

Weaning by gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) versus PS-supported SBT: A pilot study

Background and aim Studies on weaning strategies have yielded conflicting results regarding the superiority of different methods. The aim of this RCT was to compare the efficacy of gradual pressure support (PS) reduction without an initial spontaneous breathing trial (SBT) with PS-supported SBT. Methods Patients mechanically ventilated for >24 h were randomized to weaning by gradual reduction of PS without an initial SBT versus once daily SBT (PS 7 cm H 2O). The primary outcomes were the rates of successful weaning trial and time to successful extubation. The secondary outcomes were the ICU and hospital length of stay, hospital mortality and the occurrence of ventilator-associated pneumonia (VAP). Results Of the 120 patients (61 males, median age 35 years), 58 were assigned to PS and 62 to the SBT group. The median (IQR) duration of ventilation prior to weaning was 80.2 (50.5–175.6) h. The baseline characteristics were similar in the two groups except the PaO 2/FiO 2 ratio, which was significantly higher in SBT group. The rates of successful weaning trial (89.7% versus 69.4%) were significantly higher in the PS group. The median duration of weaning (66 h versus 81.5 h, P = 0.05) and the median duration of ICU stay (8 days versus 9.4 days, P = 0.027) were lower in the PS group. There was no difference in hospital stay, mortality rates or occurrence of VAP in the two arms. On multivariate analysis, the duration of ventilation prior to weaning, baseline SOFA score and the weaning method were predictors of successful extubation. Conclusions Gradual reduction of PS without an initial SBT was found to be associated with better outcomes compared to once daily PS-supported SBT.

Psychophysiological Determinants of Repeated Ventilator Weaning Failure: An Explanatory Model

The adverse effects of a failed ventilator weaning trial on the subsequent weaning attempts are not well understood. To examine physiological and psychological factors that may be predictive of risk for repeated weaning failures and prolonged mechanical ventilation. A prospective predictive study of 102 subjects, age 34 to 91 years, whose first ventilator weaning trial was unsuccessful but who were physiologically ready for another weaning attempt. Subjects were recruited from intensive care units and a respiratory care center of a tertiary medical center. Validated self-report scales and a Bicore monitoring system were used to measure ventilator patients' psychophysiological performance during the second weaning trial. Structural equation modeling was used to analyze the data and test the model. Significant causal pathways were found between fear and anxiety (r = 0.77; P < .001), anxiety and respiratory function (r = 0.24; P < .05), and respiratory function and weaning outcomes (r = 0.42; P < .001). The overall model predicted that both physiological and psychological factors were important in determining repeated failure of ventilator weaning, and the data were in support of the model (χ(2) = 29.49, P > .05). Patients whose first ventilator weaning trial is unsuccessful may be markedly fearful. Left unaddressed, these fears cause high anxiety levels that significantly compromise respiratory function and contribute to subsequent weaning failures. Thus begins a vicious cycle of repeated failure of ventilator weaning and prolonged mechanical ventilation.

Quality Improvement Interventions in Intensive Care Units

To the Editor: Dr Scales and colleagues reported that quality improvement interventions increased adoption of some (but not all) care processes in community intensive care units (ICUs) in Ontario. They noted that the ICU interprofessional team approach to patient care is well accepted, but we question whether the educational needs and methods of delivering the intervention were the same for physicians, nurses, respiratory therapists, and others. In our ICU, many nurses review educational materials about new unit practices or devices assigned by their nurse managers when they do not have patient care responsibilities. Learning these materials is part of the job, and they are held accountable by their employer, the hospital. Physicians rarely do something similar during their clinical workday. Physician education is done away from work at specific continuing medical education opportunities and is generally tied to state medical licensure and national board-certification requirements. The content presented is rarely specific to the hospital at which they work. Did the authors tailor the educational intervention to the type of clinician who would likely have the greatest responsibility for the process—ie, nurses for decubitus ulcer risk measurement, respiratory therapists for daily weaning trials, or physicians for catheter infection prevention? Differences in learning styles based on training experience and expectations about what constitutes continuing education might explain the variation in adoption by ICUs of lifesaving practices.

Simple, Difficult, or Prolonged Weaning: The Most Important Factor Is the Success or Failure of the First Weaning Trial

A recent international consensus conference[1][1] published in 2007 proposed to categorize ventilated patients into 3 groups, based on the difficulty and duration of the weaning process: “simple weaning” (group 1) includes patients who succeed the first weaning trial and are extubated without

Ultrasonographic finding of lung sliding in patients on mechanical ventilation with alveolar–interstitial syndrome

To determine the visibility of pleural lung sliding in alveolar-interstitial syndrome (AIS) in patients on mechanical ventilation at two different time points, as a confirmatory ultrasonographic method for excluding pneumothorax. Fifty-two mechanically ventilated patients in the semirecumbent position in a surgical/neurosurgical intensive care unit with ultrasonographic lung 'comet tails' in three upper anterolateral intercostal spaces, indicating the presence of AIS, were scanned for lung sliding in the same three intercostal spaces with a linear 5-10 MHz transducer after starting mechanical ventilation and on weaning trials. Pneumothorax and atelectasis were excluded by chest radiograph. Absent lung sliding was found in 22.7% of intercostal spaces scanned after starting mechanical ventilation and in 21.2% of scans taken on weaning trials. The lowest invisible rate was in patients with acute heart failure and the highest in patients with acute respiratory distress syndrome. Lung sliding specificity in AIS during mechanical ventilation was 78%. Our opinion is that different levels of airway pressure between starting mechanical ventilation and weaning trials have no influence on lung sliding visibility.

Applying a new weaning index in ICU older patients

With the increase in life expectation, more admissions to hospital, use of mechanical ventilation (MV) and weaning trials in older patients have been observed.

Listening to the Voiceless Patient: Case Reports in Assisted Communication in the Intensive Care Unit

Communication problems experienced by nonspeaking, critically ill patients in the Intensive Care Unit (ICU) have serious implications for the physical and psychological well-being of patients and the quality of their care. These problems are most profound for those with prolonged critical illnesses who are at the highest risk of dying. Recently, speech language pathologist (SLP) services have been used to provide augmentative and alternative communication (AAC) assistance to this vulnerable group of patients, their caregivers, and medical staff. Here we present three clinical cases that illustrate the application of AAC strategies across different levels of illness severity and communication impairment for nonspeaking patients in the ICU. Both high-tech communication devices with voice output and low-tech options were used for each patient according to their motor and cognitive abilities. To accommodate fluctuations in patient status and communication needs, multiple AAC strategies were integrated into the communication repertoire and tailored for each case. Medical personnel involved in these cases attributed enhanced communication efficiency, improved ventilator weaning trials, and increased patient engagement to the AAC techniques. This approach has the potential to improve symptom communication and to ease suffering for seriously ill ICU patients with speech limitations.

Study of multiparameter respiratory pattern complexity in surgical critically ill patients during weaning trials

BackgroundSeparation from mechanical ventilation is a difficult task, whereas conventional predictive indices have not been proven accurate enough, so far. A few studies have explored changes of breathing pattern variability for weaning outcome prediction, with conflicting results. In this study, we tried to assess respiratory complexity during weaning trials, using different non-linear methods derived from theory of complex systems, in a cohort of surgical critically ill patients.ResultsThirty two patients were enrolled in the study. There were 22 who passed and 10 who failed a weaning trial. Tidal volume and mean inspiratory flow were analyzed for 10 minutes during two phases: 1. pressure support (PS) ventilation (15-20 cm H2O) and 2. weaning trials with PS: 5 cm H2O. Sample entropy (SampEn), detrended fluctuation analysis (DFA) exponent, fractal dimension (FD) and largest lyapunov exponents (LLE) of the two respiratory parameters were computed in all patients and during the two phases of PS. Weaning failure patients exhibited significantly decreased respiratory pattern complexity, reflected in reduced sample entropy and lyapunov exponents and increased DFA exponents of respiratory flow time series, compared to weaning success subjects (p < 0.001). In addition, their changes were opposite between the two phases of the weaning trials. A new model including rapid shallow breathing index (RSBI), its product with airway occlusion pressure at 0.1 sec (P0.1), SampEn and LLE predicted better weaning outcome compared with RSBI, P0.1 and RSBI* P0.1 (conventional model, R2 = 0.874 vs 0.643, p < 0.001). Areas under the curve were 0.916 vs 0.831, respectively (p < 0.05).ConclusionsWe suggest that complexity analysis of respiratory signals can assess inherent breathing pattern dynamics and has increased prognostic impact upon weaning outcome in surgical patients.

Use of weaning protocols for reducing duration of mechanical ventilation in critically ill adult patients: Cochrane systematic review and meta-analysis

Objective To investigate the effects of weaning protocols on the total duration of mechanical ventilation, mortality, adverse events, quality of life, weaning duration, and length of stay in the intensive...