Increases in endotracheal tube resistance are unpredictable relative to duration of intubation

The role of diaphragmatic thickness measurement in weaning prediction and its comparison with rapid shallow breathing index: a single-center experience

Background: Acute respiratory failure (ARF) is commonly managed with invasive mechanical ventilation (IMV). The majority of the time that a patient spends on IMV is in the process of weaning. Prediction of the weaning outcome is of paramount importance, as untimely/delayed extubation is associated with a high risk of mortality. Diaphragmatic ultrasonography is a promising tool in the intensive care unit, and its utility in predicting the success of weaning remains understudied.Methods: In this prospective-observational study, we recruited 54 ARF patients on IMV, along with 50 healthy controls. During a spontaneous breathing trial, all subjects underwent diaphragmatic ultrasonography along with a rapid shallow breathing index (RSBI) assessment.Results: The mean age was 41.8±17.0 and 37.6±10.5 years among the cases and control group, respectively. Demographic variables were broadly similar in the two groups. The most common cause of ARF was obstructive airway disease. The average duration of IMV was 5.41±2.81 days. Out of 54 subjects, 45 were successfully weaned, while nine patients failed weaning. Age, body mass index, and severity of disease were similar in the successful and failed weaning patients. The sensitivity in predicting successful weaning of percent change in diaphragmatic thickness (Δtdi%) >29.71% was high (93.33%), while specificity was 66.67%. The sensitivity and specificity of mean diaphragmatic thickness (tdi) end-expiratory >0.178 cm was 60.00% and 77.78%, respectively. RSBI at 1 minute of <93.75 had an equally high sensitivity (93.33%) but a lower specificity (22.22%). Similar results were also found for RSBI measured at 5 minutes.Conclusions: During the weaning assessment, the purpose is to minimize both premature as well as delayed extubation. We found that diaphragmatic ultrasonography, in particular Δtdi%, is better than RSBI in predicting weaning outcomes.

Pulmonary biofilm-based chronic infections and inhaled treatment strategies

Certain pulmonary diseases, such as cystic fibrosis (CF), non-CF bronchiectasis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia, are usually accompanied by respiratory tract infections due to the physiological alteration of the lung immunological defenses. Recurrent infections may lead to chronic infection through the formation of biofilms. Chronic biofilm-based infections are challenging to treat using antimicrobial agents. Therefore, effective ways to eradicate biofilms and thus relieve respiratory tract infection require the development of efficacious agents for biofilm destruction, the design of delivery carriers with biofilm-targeting and/or penetrating abilities for these agents, and the direct delivery of them into the lung. This review provides an in-depth description of biofilm-based infections caused by pulmonary diseases and focuses on current existing agents that are administered by inhalation into the lung to treat biofilm, which include i) inhalable antimicrobial agents and their combinations, ii) non-antimicrobial adjuvants such as matrix-targeting enzymes, mannitol, glutathione, cyclosporin A, and iii) liposomal formulations of anti-biofilm agents. Finally, novel agents that have shown promise against pulmonary biofilms as well as traditional and new devices for pulmonary delivery of anti-biofilm agents into the lung are also discussed.

Prolonged Weaning: S2k Guideline Published by the German Respiratory Society

Mechanical ventilation (MV) is an essential part of modern intensive care medicine. MV is performed in patients with severe respiratory failure caused by respiratory muscle insufficiency and/or lung parenchymal disease; that is, when other treatments such as medication, oxygen administration, secretion management, continuous positive airway pressure (CPAP), or nasal high-flow therapy have failed. MV is required for maintaining gas exchange and allows more time to curatively treat the underlying cause of respiratory failure. In the majority of ventilated patients, liberation or "weaning" from MV is routine, without the occurrence of any major problems. However, approximately 20% of patients require ongoing MV, despite amelioration of the conditions that precipitated the need for it in the first place. Approximately 40-50% of the time spent on MV is required to liberate the patient from the ventilator, a process called "weaning". In addition to acute respiratory failure, numerous factors can influence the duration and success rate of the weaning process; these include age, comorbidities, and conditions and complications acquired during the ICU stay. According to international consensus, "prolonged weaning" is defined as the weaning process in patients who have failed at least 3 weaning attempts, or require more than 7 days of weaning after the first spontaneous breathing trial (SBT). Given that prolonged weaning is a complex process, an interdisciplinary approach is essential for it to be successful. In specialised weaning centres, approximately 50% of patients with initial weaning failure can be liberated from MV after prolonged weaning. However, the heterogeneity of patients undergoing prolonged weaning precludes the direct comparison of individual centres. Patients with persistent weaning failure either die during the weaning process, or are discharged back to their home or to a long-term care facility with ongoing MV. Urged by the growing importance of prolonged weaning, this Sk2 Guideline was first published in 2014 as an initiative of the German Respiratory Society (DGP), in conjunction with other scientific societies involved in prolonged weaning. The emergence of new research, clinical study findings and registry data, as well as the accumulation of experience in daily practice, have made the revision of this guideline necessary. The following topics are dealt with in the present guideline: Definitions, epidemiology, weaning categories, underlying pathophysiology, prevention of prolonged weaning, treatment strategies in prolonged weaning, the weaning unit, discharge from hospital on MV, and recommendations for end-of-life decisions. Special emphasis was placed on the following themes: (1) A new classification of patient sub-groups in prolonged weaning. (2) Important aspects of pulmonary rehabilitation and neurorehabilitation in prolonged weaning. (3) Infrastructure and process organisation in the care of patients in prolonged weaning based on a continuous treatment concept. (4) Changes in therapeutic goals and communication with relatives. Aspects of paediatric weaning are addressed separately within individual chapters. The main aim of the revised guideline was to summarize both current evidence and expert-based knowledge on the topic of "prolonged weaning", and to use this information as a foundation for formulating recommendations related to "prolonged weaning", not only in acute medicine but also in the field of chronic intensive care medicine. The following professionals served as important addressees for this guideline: intensivists, pulmonary medicine specialists, anaesthesiologists, internists, cardiologists, surgeons, neurologists, paediatricians, geriatricians, palliative care clinicians, rehabilitation physicians, intensive/chronic care nurses, physiotherapists, respiratory therapists, speech therapists, medical service of health insurance, and associated ventilator manufacturers.

Measurement of subglottic diameter and distance to pre-epiglottic space among Chinese adults

Proper endotracheal tube (ETT) size selection and identification of potentially difficult airways are important to reduce laryngeal injury during intubation. However, controversies exist concerning transverse subglottic diameter—the narrowest part of the airway—and the distance to pre-epiglottic space. Because few studies have reported the distance from skin to the midpoint of the epiglottis (DSE) among normal individuals, whether the DSE varies between individuals and by ethnicity remains uncertain. The present study aims to investigate the sonographic subglottic diameter and DSE among healthy Chinese adults. Healthy volunteers were recruited at National Taiwan University Hospital between October and November 2019. Exclusion criteria included pre-existing airway or respiratory diseases, neck tumors, and a history of neck operation. Age, sex, height, weight, body mass index (BMI), sonographic DSE, and transverse subglottic diameter were recorded. A total of 124 participants were enrolled. The average age was 32.5 ± 10.4 years and 63 participants (51%) were males. The subglottic diameter was positively associated with sex (males, 14.40 mm; females, 11.10 mm, p < 0.001) and BMI (underweight, 12.13 mm; normal weight, 12.47 mm; overweight, 13.80 mm; obese, 13.67 mm, p = 0.007). Moreover, the DSE was shorter in males (male, 16.18 mm; females, 14.54 mm, p < 0.001) and participants with increased BMI (underweight, 13.70 mm; normal weight, 15.06 mm; overweight, 16.58 mm; obese, 18.18 mm, p < 0.001). As compared with other ethnicity, a smaller size of subglottic diameter and a shorter DSE were noted among Chinese participants, and we suggest that a relatively smaller size of endotracheal tube selection should be considered in tracheal intubations.

Tracheal tube size in adults undergoing elective surgery - a narrative review

Tracheal tubes are routinely used in adults undergoing elective surgery. The size of the tracheal tube, defined by its internal diameter, is often generically selected according to sex, with 7-7.5 mm and 8-8.5 mm tubes recommended in women and men, respectively. Tracheal diameter in adults is highly variable, being narrowest at the subglottis, and is affected by height and sex. The outer diameter of routinely used tracheal tubes may exceed these dimensions, traumatise the airway and increase the risk of postoperative sore throat and hoarseness. These complications disproportionately affect women and may be mitigated by using smaller tracheal tubes (6-6.5 mm). Patient safety concerns about using small tracheal tubes are based on critical care populations undergoing prolonged periods of tracheal intubation and not patients undergoing elective surgery. The internal diameter of the tube corresponds to its clinical utility. Tracheal tubes as small as 6.0 mm will accommodate routinely used intubation aids, suction devices and slim-line fibreoptic bronchoscopes. Positive pressure ventilation may be performed without increasing the risk of ventilator-induced lung injury or air trapping, even when high minute volumes are required. There is also no demonstrable increased risk of aspiration or cuff pressure damage when using smaller tracheal tubes. Small tracheal tubes may not be safe in all patients, such as those with high secretion loads and airflow limitation. A balanced view of risks and benefits should be taken appropriate to the clinical context, to select the smallest tracheal tube that permits safe peri-operative management.

Ex Vivo Evaluation of Secretion-Clearing Device in Reducing Airway Resistance within Endotracheal Tubes

Background

Secretions accumulate in endotracheal tubes' (ETT) lumens upon their placement in patients. The secretions impact airway resistance and pressure. Secretions potentiate prolonged mechanical ventilation and ventilator-associated pneumonia. Our primary objective in this study was to evaluate an ETT-clearing device (ETT-CD) in its ability to remove secretions from ex vivo ETT lumens.

Methods

Forty ETTs, obtained from intensive care patients at extubation, were individually placed into a ventilator field performance testing simulator at 37°C. The pressure drop through the ETTs was measured at a flow rate of 60 L/min before and after cleaning with the ETT-CD and compared with unused, similarly sized controls tubes. The ETT-CD was inserted into an ETT until the tip reached Murphy's eye (hole in the side) of the ETT. The wiper, set back from the tip, was expanded by ETT-CD handle activation. As the ETT-CD was removed, the distal wiper extracted secretions from the ETT lumen.

Results

Forty ETTs were tested with nonparametric Wilcoxon signed-rank tests. Before being cleared with the ETT-CD, the median pressure drop in the extubated 7.5 mm ETTs was 17.8 cm H₂O; after ETT-CD use, it was 12.3. The cleared ETTs were significantly improved over the ETTs before being cleared (p < 0.001); however, there remained a significant difference between the cleared ETTs and the control tubes (p=0.005), indicating the clearing was not to the level of an unused ETT. Similar results were determined for the 8.0 mm ETTs.

Conclusions

For the 7.5 mm and the 8.0 mm EETs, the ETT-CD improved effective patency of the ETTs over the uncleared ETTs, independent of occlusion location, tube size, or length of tube. However, there remained a significant difference between the cleared tubes and controls.

Effect of the endOclear® Device on Biofilm in Endotracheal Tubes

BACKGROUND

Organisms trapped in biofilms cause more than 80% of medical infections. Significant investments are being made to develop methods of removing these biofilms. The endOclear^® device is reported to remove biofilm from endotracheal tubes (ETTs) and to decrease pneumonia rates and ventilator time.

METHODS

This was an observational study performed at a university Level 1 trauma center intensive care unit. A series of 40 ETTs were collected at extubation, with half of the patients having been treated daily with the endOclear^® device. Biofilms were quantified from a standardized point on the distal ETT. The patients' standard and biofilm cultures were reviewed.

RESULTS

The mean hours of intubation for the control group was 135 and for the device group 138. This difference was not statistically significant (p = 0.91). Eleven patients in the device group were found to have pneumonia compared with six in the control group (p = 0.34). Ventilator data after device use showed a mean increase of 29.9 cc in tidal volume and a mean decrease in peak pressures of 0.39 cm H₂O. Comparisons between biofilm stage or hours of intubation and a diagnosis of pneumonia found no correlation. Only nine of 40 ETTs had congruence between the microbiata of the biofilm and standard bronchoalveolar lavage (BAL) fluid, a divergence rate of 78%.

CONCLUSIONS

Comparison of the endOclear^® group and controls demonstrated a trend toward a higher pneumonia rate in the former. Additionally, the device achieved very small, clinically insignificant, changes in ventilator settings, and no difference was seen in the time on the ventilator. Comparisons between biofilm and standard BAL cultures continue to show the biofilm is more diverse than previously thought. In this study, no statistical significance was found between biofilm stage and the pneumonia rate. This study provides additional evidence that there is no correlation between biofilm stage and duration of intubation.

Micropatterned Endotracheal Tubes Reduce Secretion-Related Lumen Occlusion

Tracheal intubation disrupts physiological homeostasis of secretion production and clearance, resulting in secretion accumulation within endotracheal tubes (ETTs). Novel in vitro and in vivo models were developed to specifically recapitulate the clinical manifestations of ETT occlusion. The novel Sharklet™ micropatterned ETT was evaluated, using these models, for the ability to reduce the accumulation of both bacterial biofilm and airway mucus compared to a standard care ETT. Novel ETTs with micropattern on the inner and outer surfaces were placed adjacent to standard care ETTs in in vitro biofilm and airway patency (AP) models. The primary outcome for the biofilm model was to compare commercially-available ETTs (standard care and silver-coated) to micropatterned for quantity of biofilm accumulation. The AP model's primary outcome was to evaluate accumulation of artificial airway mucus. A 24-h ovine mechanical ventilation model evaluated the primary outcome of relative quantity of airway secretion accumulation in the ETTs tested. The secondary outcome was measuring the effect of secretion accumulation in the ETTs on airway resistance. Micropatterned ETTs significantly reduced biofilm by 71% (p = 0.016) compared to smooth ETTs. Moreover, micropatterned ETTs reduced lumen occlusion, in the AP model, as measured by cross-sectional area, in distal (85%, p = 0.005), middle (84%, p = 0.001) and proximal (81%, p = 0.002) sections compared to standard care ETTs. Micropatterned ETTs reduced the volume of secretion accumulation in a sheep model of occlusion by 61% (p < 0.001) after 24 h of mechanical ventilation. Importantly, micropatterned ETTs reduced the rise in ventilation peak inspiratory pressures over time by as much as 49% (p = 0.005) compared to standard care ETTs. Micropatterned ETTs, demonstrated here to reduce bacterial contamination and mucus occlusion, will have the capacity to limit complications occurring during mechanical ventilation and ultimately improve patient care.

Pediatric extubation readiness tests should not use pressure support

PURPOSE

Pressure support is often used for extubation readiness testing, to overcome perceived imposed work of breathing from endotracheal tubes. We sought to determine whether effort of breathing on continuous positive airway pressure (CPAP) of 5 cmH2O is higher than post-extubation effort, and if this is confounded by endotracheal tube size or post-extubation noninvasive respiratory support.

METHODS

Prospective trial in intubated children. Using esophageal manometry we compared effort of breathing with pressure rate product under four conditions: pressure support 10/5 cmH2O, CPAP 5 cmH2O (CPAP), and spontaneous breathing 5 and 60 min post-extubation. Subgroup analysis excluded post-extubation upper airway obstruction (UAO) and stratified by endotracheal tube size and post-extubation noninvasive respiratory support.

RESULTS

We included 409 children. Pressure rate product on pressure support [100 (IQR 60, 175)] was lower than CPAP [200 (120, 300)], which was lower than 5 min [300 (150, 500)] and 60 min [255 (175, 400)] post-extubation (all p < 0.01). Excluding 107 patients with post-extubation UAO (where pressure rate product after extubation is expected to be higher), pressure support still underestimated post-extubation effort by 126-147 %, and CPAP underestimated post-extubation effort by 17-25 %. For all endotracheal tube subgroups, ≤3.5 mmID (n = 152), 4-4.5 mmID (n = 102), and ≥5.0 mmID (n = 48), pressure rate product on pressure support was lower than CPAP and post-extubation (all p < 0.0001), while CPAP pressure rate product was not different from post-extubation (all p < 0.05). These findings were similar for patients extubated to noninvasive respiratory support, where pressure rate product on pressure support before extubation was significantly lower than pressure rate product post-extubation on noninvasive respiratory support (p < 0.0001, n = 81).

CONCLUSIONS

Regardless of endotracheal tube size, pressure support during extubation readiness tests significantly underestimates post-extubation effort of breathing.

Tracheal tube obstruction in mechanically ventilated patients assessed by high-resolution computed tomography

BACKGROUND

Tracheal intubation compromises mucus clearance and secretions accumulate inside the tracheal tube (TT). The aim of this study was to evaluate with a novel methodology TT luminal obstruction in critically ill patients.

METHODS

This was a three-phase study: (1) the authors collected 20 TTs at extubation. High-resolution computed tomography (CT) was performed to determine cross-sectional area (CSA) and mucus distribution within the TT; (2) five TTs partially filled with silicone were used to correlate high-resolution CT results and increased airflow resistance; and (3) 20 chest CT scans of intubated patients were reviewed for detection of secretions in ventilated patients' TT.

RESULTS

Postextubation TTs showed a maximum CSA reduction of (mean±SD) 24.9±3.9% (range 3.3 to 71.2%) after a median intubation of 4.5 (interquartile range 2.5 to 6.5) days. CSA progressively decreased from oral to lung end of used TTs. The luminal volume of air was different between used and new TTs for all internal diameters (P<0.01 for new vs. used TTs for all studied internal diameters). The relationship between pressure drop and increasing airflow rates was nonlinear and depended on minimum CSA available to ventilation. Weak correlation was found between TT occlusion and days of intubation (R²=0.352, P=0.006). With standard clinical chest CT scans, 6 of 20 TTs showed measurable secretions with a CSA reduction of 24.0±3.9%.

CONCLUSIONS

TT luminal narrowing is a common finding and correlates with increased airflow resistance. The authors propose high-resolution CT as a novel technique to visualize and quantify secretions collected within the TT lumen.

A systematic review on tracheostomy decannulation: a proposal of a quantitative semiquantitative clinical score

Background

Tracheostomy is one of the most common surgical procedures performed in critical care patient management; more specifically, ventilation through tracheal cannula allows removal of the endotracheal tube (ETT). Available literature about tracheostomy care and decannulation is mainly represented by expert opinions and no certain knowledge arises from it.

Methods

In lack of statistical requirements, a systematic and critical review of literature regarding tracheostomy tube removal was performed in order to assess predictor factors of successful decannulation and to propose a predictive score. We combined 3 terms and a literature search has been performed using the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE via Ovid SP; EMBASE via Ovid SP; EBSCO. Abstracts were independently reviewed: for those studies fitting the inclusion criteria on the basis of the title and abstract, full-text was achieved. We included studies published from January 1, 1995 until March 31, 2014; any sort of review and expert opinion has been excluded by our survey. English language restriction was applied. Ten studies have been considered eligible for inclusion in the review and were analysed further.

Results

Cough effectiveness and ability to tolerate tracheostomy tube capping are the most considered parameters in clinical practice; other parameters are taken into different consideration by many authors in order to proceed to decannulation. Among them, we distinguished between objective quantitative parameters and semi-quantitative parameters more dependent from clinician’s opinion. We then built a score (the Quantitative semi Quantitative score: QsQ score) based on selected parameters coming from literature.

Conclusions

On our knowledge, this review provides the first proposal of decannulation score system based on current literature that is hypothetical and requires to be validated in daily practice. The key point of our proposal is to give a higher value to the objective parameters coming from literature compared to less quantifiable clinical ones.

Tracheostomy in stroke patients

OPINION STATEMENT

Patients with severe ischemic and hemorrhagic stroke may require tracheostomy in the course of their disease. This may apply to stroke unit patients whose deficits include a severe dysphagia posing such risk of aspiration as it cannot be sufficiently counteracted by tube feeding and swallowing therapy alone. More often, however, tracheostomy is performed in stroke patients so severely afflicted that they require intensive care unit treatment and mechanical ventilation. In these, long-term ventilation and prolonged insufficient airway protection are the main indications for tracheostomy. Accepted advantages are less pharyngeal and laryngeal lesions than with prolonged orotracheal intubation, better oral hygiene and nursing care, and higher patient comfort. Optimal timing of tracheostomy is unclear, in general, as in stroke intensive care unit patients. Potential benefits of early tracheostomy concerning ventilation duration and length of stay, respirator weaning, airway safety, rate of pneumonia, and other complications, outcome and mortality have been suggested in studies on non-neurologic subgroups of critical care patients. Stroke patients have hardly been investigated with regard to these aspects, and mainly retrospectively. A single randomized pilot trial on early tracheostomy in 60 ventilated patients with severe hemorrhagic and ischemic stroke demonstrated feasibility, safety, and less need of sedation. Regarding the technique, bedside percutaneous dilational tracheostomy should be preferred over surgical tracheostomy because of several reported advantages. As the procedural risk is low and early tracheostomy does not seem to worsen the clinical course of the ventilated stroke patient, it is reasonable to assess the need of further ventilation at the end of the first week of intensive care and proceed to tracheostomy if extubation is not feasible. Reliable prediction of prolonged ventilation need and outcome benefits of early tracheostomy, however, await further clarification. Decannulation of stroke patients after discontinued ventilation has to follow reliable confirmation of swallowing ability, as by endoscopy.

A clinical assessment of the Mucus Shaver: a device to keep the endotracheal tube free from secretions

OBJECTIVE

: We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver.

DESIGN

: Prospective, randomized trial.

SETTING

: University hospital intensive care unit.

PATIENTS

: We enrolled 24 patients expected to remain ventilated for >72 hrs.

INTERVENTIONS

: The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3-5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation.

MEASUREMENTS AND MAIN RESULTS

: During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 μm as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver.

CONCLUSIONS

: The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

Rohrer's constant, K2, as a factor of determining inspiratory resistance of common adult endotracheal tubes

The aim of the study was to calculate the in vitro inspiratory resistance (R(ETT)) of adult endotracheal tubes (ETT), via the end-inspiratory occlusion method, and to apply this method in vivo in order to estimate R(ETT) value in real time. By plotting R(ETT) over inspiratory flow (V) and calculating Rohrer's coefficients of linear and nonlinear resistance, K1 and K2 respectively, we determined the resistive behaviour of each ETT. Peak and plateau pressures were recorded at both proximal and distal sites of the ETT after applying a three-second occlusion under constant flow. Distal pressure was obtained via an intraluminal catheter R(ETT) was calculated as (P(peak) - P(plateau))/(V), at both sites. R(ETT) value resulted from the difference R(proximal) - R(distal). Graph R(ETT) over (V) was plotted and Rohrer's constants were calculated by the method of least squares. For ETTs with inner diameter 9.0, 8.5, 8.0, 7.5, 7.0 and 6.5 mm, K2 was 2.42, 3.05, 4.65, 6.01, 9.17 and 12.80 cmH2O/l/s, respectively. The intraluminal catheter increased R(ETT) No.7.0 by an average of 49%. Finally, ten patients with partially obstructed ETTs were tested and K2 in vivo constants found to be higher than their corresponding in vitro values (P value 0.00012). Therefore, knowing the performing size of an ETT may help the clinicians identify ETT obstruction and deal with weaning problems.

Clinical review: the ABC of weaning failure--a structured approach

About 20% to 30% of patients are difficult to wean from invasive mechanical ventilation. The pathophysiology of difficult weaning is complex. Accordingly, determining the reason for difficult weaning and subsequently developing a treatment strategy require a dedicated clinician with in-depth knowledge of the pathophysiology of weaning failure. This review presents a structural framework ('ABCDE') for the assessment and treatment of difficult-to-wean patients. Earlier recognition of the underlying causes may expedite weaning from mechanical ventilation.