Practice Variation in Spontaneous Breathing Trial Performance and Reporting

Spontaneous breathing trials (SBTs) are standard of care in assessing extubation readiness; however, there are no universally accepted guidelines regarding their precise performance and reporting.  To investigate variability in SBT practice across centres.  Data from 680 patients undergoing 931 SBTs from eight North American centres from the Weaning and Variability Evaluation (WAVE) observational study were examined. SBT performance was analyzed with respect to ventilatory support, oxygen requirements, and sedation level using the Richmond Agitation Scale Score (RASS). The incidence of use of clinical extubation criteria and changes in physiologic parameters during an SBT were assessed.  The majority (80% and 78%) of SBTs used 5 cmH2O of ventilator support, although there was variability. A significant range in oxygenation was observed. RASS scores were variable, with RASS 0 ranging from 29% to 86% and 22% of SBTs performed in sedated patients (RASS < −2). Clinical extubation criteria were heterogeneous among centres. On average, there was no change in physiological variables during SBTs.  The present study highlights variation in SBT performance and documentation across and within sites. With their impact on the accuracy of outcome prediction, these results support efforts to further clarify and standardize optimal SBT technique.

Related papers:

title: Respiratory weakness is associated with limb weakness and delayed weaning in critical illness*
abstract: Although critical illness neuromyopathy might interfere with weaning from mechanical ventilation, its respiratory component has not been investigated. We designed a study to assess the level of respiratory muscle weakness emerging during the intensive care unit stay in mechanically ventilated patients and to examine the correlation between respiratory and limb muscle strength and the specific contribution of respiratory weakness to delayed weaning. Prospective observational study. Two medical, one surgical, and one medicosurgical intensive care units in two university hospitals and one university- affiliated hospital. A total of 116 consecutive patients were enrolled after ≥7 days of mechanical ventilation. None. Maximal inspiratory and expiratory pressures and vital capacity were measured via the tracheal tube on the first day of return to normal consciousness. Muscle strength was measured using the Medical Research Council score. After standardized weaning, successful extubation was defined as the day from which mechanical ventilatory support was no longer required within the next 15 days. The median value (interquartile range) of maximal inspiratory pressure was 30 (20–40) cm H2O, maximal expiratory pressure was 30 (20–50) cm H2O, and vital capacity was 11.1 (6.3–19.8) mL/kg. Maximal inspiratory pressure, maximal expiratory pressure, and vital capacity were significantly correlated with the Medical Research Council score. The median time (interquartile range) from awakening to successful extubation was 6 (1–17) days. Low maximal inspiratory pressure (hazard ratio, 1.86; 95% confidence interval, 1.07–3.23), maximal expiratory pressure (hazard ratio, 2.18; 95% confidence interval, 1.44–3.84), and Medical Research Council score (hazard ratio, 1.96; 95% confidence interval, 1.27–3.02) were independent predictors of delayed extubation. Septic shock before awakening was significantly associated with respiratory weakness (odds ratio, 3.17; 95% confidence interval, 1.17–8.58). Respiratory and limb muscle strength are both altered after 1 wk of mechanical ventilation. Respiratory muscle weakness is associated with delayed extubation and prolonged ventilation. In our study, septic shock is a contributor to respiratory weakness.

title: Epidemiology and outcomes of ventilator-associated pneumonia in a large US database.
abstract: To evaluate risk factors for ventilator-associated pneumonia (VAP), as well as its influence on in-hospital mortality, resource utilization, and hospital charges.



Retrospective matched cohort study using data from a large US inpatient database.



Patients admitted to an ICU between January 1998 and June 1999 who received mechanical ventilation for > 24 h.



Risk factors for VAP were examined using crude and adjusted odds ratios (AORs). Cases of VAP were matched on duration of mechanical ventilation, severity of illness on admission (predicted mortality), type of admission (medical, surgical, trauma), and age with up to three control subjects. Mortality, resource utilization, and billed hospital charges were then compared between cases and control subjects.



Of the 9,080 patients meeting study entry criteria, VAP developed in 842 patients (9.3%). The mean interval between intubation, admission to the ICU, hospital admission, and the identification of VAP was 3.3 days, 4.5 days, and 5.4 days, respectively. Identified independent risk factors for the development of VAP were male gender, trauma admission, and intermediate deciles of underlying illness severity (on admission) [AOR, 1.58, 1.75, and 1.47 to 1.70, respectively]. Patients with VAP were matched with 2,243 control subjects without VAP. Hospital mortality did not differ significantly between cases and matched control subjects (30.5% vs 30.4%, p = 0.713). Nevertheless, patients with VAP had a significantly longer duration of mechanical ventilation (14.3 +/- 15.5 days vs 4.7 +/- 7.0 days, p < 0.001), ICU stay (11.7 +/- 11.0 days vs 5.6 +/- 6.1 days, p < 0.001), and hospital stay (25.5 +/- 22.8 days vs 14.0 +/- 14.6 days, p < 0.001). Development of VAP was also associated with an increase of > $40,000 USD in mean hospital charges per patient ($104,983 USD +/- $91,080 USD vs $63,689 USD+/- $75,030 USD, p < 0.001).



This retrospective matched cohort study, the largest of its kind, demonstrates that VAP is a common nosocomial infection that is associated with poor clinical and economic outcomes. While strategies to prevent the occurrence of VAP may not reduce mortality, they may yield other important benefits to patients, their families, and hospital systems.

title: Risk factors for and economic implications of prolonged ventilation after cardiac surgery.
abstract: The study's objective was to identify predictors of prolonged ventilation and assess clinical and cost implications in patients undergoing cardiac surgery.



Patients undergoing cardiac surgery were classified as (1) ventilated less than 96 hours or (2) ventilated 96 hours or more. Multivariate modeling was used to identify predictors of prolonged ventilation and to ascertain the impact of prolonged ventilation on in-hospital mortality and bed occupancy costs and 5-year survival.



A total of 7553 patients were studied; 197 (2.6%) had prolonged ventilation. Median ventilation times were 8 and 192 hours, and in-hospital mortality was 1.0% and 22.2% in the control and prolonged ventilation groups, respectively (P < .001). In-hospital mortality remained higher in the prolonged ventilation group after adjustment and when comparing propensity-matched patients (odds ratio 8.06; 95% confidence interval [CI] 4.27-15.2; P < .001 for propensity-matched groups). Independent predictors of prolonged ventilation were as follows: older age, New York Heart Association class, ejection fraction less than 50%, creatinine greater than 200 micromol/L, multiple valve replacements, aortic procedures, operative priority, reoperation for bleeding, inotropes, and preoperative intra-aortic balloon pump. Five-year survival was lower in the prolonged ventilation group (56.1% [95% CI 46.6%-64.6%] vs 88.8% [95% CI 87.9%-89.6%]) also after adjustment for imbalances and when comparing propensity-matched patients (hazard ratio 2.39; 95% CI 1.75-3.27; P < .001 for propensity-matched groups). Mean bed occupancy costs were 14,286 dollars (95% CI 12,731 dollars-15,690 dollars) and 2761 dollars (95% CI 2705 dollars-2814 dollars) in the prolonged ventilation and control groups, respectively (P < .001).



Prolonged ventilation is associated with high in-hospital mortality and costs, and poor 5-year survival. Identified predictors of prolonged ventilation might help to optimize the clinical management of these patients.

title: A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation
abstract: The traditional predictors of the outcome of weaning from mechanical ventilation — minute ventilation (VE) and maximal inspiratory pressure (P1max) — are frequently inaccurate. We developed two new indexes: the first quantitates rapid shallow breathing as the ratio of respiratory frequency to tidal volume (f/VT), and the second is termed CROP, because it integrates thoracic compliance, respiratory ṟate, arterial oxygenation, and P1max.  The threshold values for each index that discriminated best between a successful and an unsuccessful outcome of weaning were determined in 36 patients, and the predictive accuracy of these values was then tested prospectively in an additional 64 patients. Sensitivity and specificity were calculated, and the data were also analyzed with receiver-operating-characteristic (ROC) curves, in which the proportions of true positive results and false positive results are plotted against each other for a number of threshold values of an index; the area...

title: Effect of failed extubation on the outcome of mechanical ventilation.
abstract: To examine medical outcomes associated with reintubation for extubation failure after discontinuation of mechanical ventilation.



Prospective cohort study of consecutive intubated medical ICU patients who underwent a trial of extubation at a tertiary-care teaching hospital. The failed extubation group consisted of all patients reintubated within 72 h or within 7 days (if continuous ICU care had been required) of extubation. All others were considered to be successfully extubated. Study end points included hospital death vs survival, the number of days spent in the ICU and in the hospital after the onset of mechanical ventilation, the likelihood of requiring > or = 7 or > or = 14 days of ICU care after extubation, and the need for transfer to either a long-term care or rehabilitation facility among the survivors.



Of 289 intubated patients, 247 (85%) were successfully extubated, and 42 (15%) required reintubation for failed extubation (time to reintubation 1.5+/-0.2 days). Reintubation for extubation failure resulted in 12 additional days of mechanical ventilation. When compared with successfully extubated patients, reintubated patients were more likely to die in the hospital (43% vs 12%; p<0.0001), spend more time in the ICU (21.2+/-2.8 days vs 4.5+/-0.6 days; p<0.001) and in the hospital (30.5+/-3.3 days vs 16.3+/-1.2 days; p<0.001) after extubation, and require transfer to a long-term care or rehabilitation facility (38% vs 21%; p<0.05). Using multiple logistic regression, extubation failure was an independent predictor for death and the need for transfer to a long-term care facility. Compared with those successfully extubated, patients who failed extubation were seven times (p<0.0001) more likely to die, 31 times (p<0.0001) more likely to spend > or = 14 days in the ICU after extubation, and six times (p<0.001) more likely to need transfer to a long-term care or rehabilitation facility if they survived.



After adjusting for severity of illness and comorbid conditions, extubation failure had a significant independent association with increased risk for death, prolonged ICU stay, and transfer to a long-term care or rehabilitation facility. Extubation failure may serve as an additional independent marker of severity of illness. Alternatively, poor outcomes may be etiologically related to extubation failure. If the latter proves to be the case, identifying patients at risk for poor outcomes from extubation failure and instituting alternative care practices may reduce mortality, duration of ICU stay, and need for transfer to a long-term care facility.

title: Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation. Spanish Lung Failure Collaborative Group.
abstract: The duration of spontaneous breathing trials before extubation has been set at 2 h in research studies, but the optimal duration is not known. We conducted a prospective, multicenter study involving 526 ventilator-supported patients considered ready for weaning, to compare clinical outcomes for trials of spontaneous breathing with target durations of 30 and 120 min. Of the 270 and 256 patients in the 30- and 120-min trial groups, respectively, 237 (87.8%) and 216 (84.8%), respectively, completed the trial without distress and were extubated (p = 0.32); 32 (13.5%) and 29 (13.4%), respectively, of these patients required reintubation within 48 h. The percentage of patients who remained extubated for 48 h after a spontaneous breathing trial did not differ in the 30- and 120-min trial groups (75.9% versus 73.0%, respectively, p = 0.43). The 30- and 120-min trial groups had similar within-unit mortality rates (13 and 9%, respectively) and in-hospital mortality rates (19 and 18%, respectively). Reintubation was required in 61 (13.5%) patients, and these patients had a higher mortality (20 of 61, 32.8%) than did patients who tolerated extubation (18 of 392, 4.6%) (p < 0.001). Neither measurements of respiratory frequency, heart rate, systolic blood pressure, and oxygen saturation during the trial, nor other functional measurements before the trial discriminated between patients who required reintubation from those who tolerated extubation. In conclusion, after a first trial of spontaneous breathing, successful extubation was achieved equally effectively with trials targeted to last 30 and 120 min.

title: Daily cost of an intensive care unit day: The contribution of mechanical ventilation*
abstract: To quantify the mean daily cost of intensive care, identify key factors associated with increased cost, and determine the incremental cost of mechanical ventilation during a day in the intensive care unit. Retrospective cohort analysis using data from NDCHealth’s Hospital Patient Level Database. A total of 253 geographically diverse U.S. hospitals. The study included 51,009 patients ≥18 yrs of age admitted to an intensive care unit between October 1, 2002, and December 31, 2002. None. Days of intensive care and mechanical ventilation were identified using billing data, and daily costs were calculated as the sum of daily charges multiplied by hospital-specific cost-to-charge ratios. Cost data are presented as mean (±sd). Incremental daily cost of mechanical ventilation was calculated using log-linear regression, adjusting for patient and hospital characteristics. Approximately 36% of identified patients were mechanically ventilated at some point during their intensive care unit stay. Mechanically ventilated patients were older (63.5 yrs vs. 61.7 yrs, p < .0001) and more likely to be male (56.1% vs. 51.8%, p < 0.0001), compared with patients who were not mechanically ventilated, and required mechanical ventilation for a mean duration of 5.6 days ± 9.6. Mean intensive care unit cost and length of stay were $31,574 ± 42,570 and 14.4 days ± 15.8 for patients requiring mechanical ventilation and $12,931 ± 20,569 and 8.5 days ± 10.5 for those not requiring mechanical ventilation. Daily costs were greatest on intensive care unit day 1 (mechanical ventilation, $10,794; no mechanical ventilation, $6,667), decreased on day 2 (mechanical ventilation:, $4,796; no mechanical ventilation, $3,496), and became stable after day 3 (mechanical ventilation, $3,968; no mechanical ventilation, $3,184). Adjusting for patient and hospital characteristics, the mean incremental cost of mechanical ventilation in intensive care unit patients was $1,522 per day (p < .001). Intensive care unit costs are highest during the first 2 days of admission, stabilizing at a lower level thereafter. Mechanical ventilation is associated with significantly higher daily costs for patients receiving treatment in the intensive care unit throughout their entire intensive care unit stay. Interventions that result in reduced intensive care unit length of stay and/or duration of mechanical ventilation could lead to substantial reductions in total inpatient cost.

title: Predicting success in weaning from mechanical ventilation.
abstract: We identified 65 observational studies of weaning predictors that had been reported in 70 publications. After grouping predictors with similar names but different thresholds, the following predictors met our relevance criteria: heterogeneous populations, 51; COPD patients, 21; and cardiovascular ICU patients, 45. Many variables were of no use in predicting the results of weaning. Moreover, few variables had been studied in > 50 patients or had results presented to generate estimates of predictive power. For stepwise reductions in mechanical support, the most promising predictors were a rapid shallow breathing index (RSBI) < 65 breaths/min/L (measured using the ventilator settings that were in effect at the time that the prediction was made) and a pressure time product < 275 cm H2O/L/s. The pooled likelihood ratios (LRs) were 1.1 (95% confidence interval [CI], 0.95 to 1.28) for a respiratory rate [RR] of < 38 breaths/min and 0.32 (95% CI, 0.06 to 1.71) for an RR of > 38 breaths/min, which indicate that an RR of < 38 breaths/min leaves the probability of successful weaning virtually unchanged but that a value of > 38 breaths/min leads to a small reduction in the probability of success in weaning the level of mechanical support. For trials of unassisted breathing, the most promising weaning predictors include the following: RR; RSBI; a product of RSBI and occlusion pressure < 450 cm H2O breaths/min/L; maximal inspiratory pressure (PImax) < 20 cm H2O; and a knowledge-based system for adjusting pressure support. Pooled results for the power of a positive test result for both RR and RSBI were limited (highest LR, 2.23), while the power of a negative test result was substantial (ie, LR, 0.09 to 0.23). Summary data suggest a similar predictive power for RR and RSBI. In the prediction of successful extubation, an RR of < 38 breaths/min (sensitivity, 88%; specificity, 47%), an RSBI < 100 or 105 breaths/min/L (sensitivity, 65 to 96%; specificity, 0 to 73%), PImax, and APACHE (acute physiology and chronic health evaluation) II scores that are obtained at hospital admission appear to be the most promising. After pooling, two variables appeared to have some value. An RR of > 38 breaths/min and an RSBI of > 100 breaths/min/L appear to reduce the probability of successful extubation, and PImax < 0.3, for which the pooled LR is 2.23 (95% CI, 1.15 to 4.34), appears to marginally increase the likelihood of successful extubation. Judging by areas under the receiver operator curve for all variables, none of these variables demonstrate more than modest accuracy in predicting weaning outcome. Why do most of these tests perform so poorly? The likely explanation is that clinicians have already considered the results when they choose patients for trials of weaning.

title: Pressure support versus T-tube for weaning from mechanical ventilation in adults.
abstract: Mechanical ventilation is important in caring for patients with critical illness. Clinical complications, increased mortality, and high costs of health care are associated with prolonged ventilatory support or premature discontinuation of mechanical ventilation. Weaning refers to the process of gradually or abruptly withdrawing mechanical ventilation. The weaning process begins after partial or complete resolution of the underlying pathophysiology precipitating respiratory failure and ends with weaning success (successful extubation in intubated patients or permanent withdrawal of ventilatory support in tracheostomized patients).



To evaluate the effectiveness and safety of two strategies, a T-tube and pressure support ventilation, for weaning adult patients with respiratory failure that required invasive mechanical ventilation for at least 24 hours, measuring weaning success and other clinically important outcomes.



We searched the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 6); MEDLINE (via PubMed) (1966 to June 2012); EMBASE (January 1980 to June 2012); LILACS (1986 to June 2012); CINAHL (1982 to June 2012); SciELO (from 1997 to August 2012); thesis repository of CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) (http://capesdw.capes.gov.br/capesdw/) (August 2012); and Current Controlled Trials (August 2012).We reran the search in December 2013. We will deal with any studies of interest when we update the review.



We included randomized controlled trials (RCTs) that compared a T-tube with pressure support (PS) for the conduct of spontaneous breathing trials and as methods of gradual weaning of adult patients with respiratory failure of various aetiologies who received invasive mechanical ventilation for at least 24 hours.



Two authors extracted data and assessed the methodological quality of the included studies. Meta-analyses using the random-effects model were conducted for nine outcomes. Relative risk (RR) and mean difference (MD) or standardized mean difference (SMD) were used to estimate the treatment effect, with 95% confidence intervals (CI).



We included nine RCTs with 1208 patients; 622 patients were randomized to a PS spontaneous breathing trial (SBT) and 586 to a T-tube SBT. The studies were classified into three categories of weaning: simple, difficult, and prolonged. Four studies placed patients in two categories of weaning. Pressure support ventilation (PSV) and a T-tube were used directly as SBTs in four studies (844 patients, 69.9% of the sample). In 186 patients (15.4%) both interventions were used along with gradual weaning from mechanical ventilation; the PS was gradually decreased, twice a day, until it was minimal and periods with a T-tube were gradually increased to two and eight hours for patients with difficult and prolonged weaning. In two studies (14.7% of patients) the PS was lowered to 2 to 4 cm H2O and 3 to 5 cm H2O based on ventilatory parameters until the minimal PS levels were reached. PS was then compared to the trial with the T-tube (TT).We identified 33 different reported outcomes in the included studies; we took 14 of them into consideration and performed meta-analyses on nine. With regard to the sequence of allocation generation, allocation concealment, selective reporting and attrition bias, no study presented a high risk of bias. We found no clear evidence of a difference between PS and TT for weaning success (RR 1.07, 95% CI 0.97 to 1.17, 9 studies, low quality of evidence), intensive care unit (ICU) mortality (RR 0.81, 95% CI 0.53 to 1.23, 5 studies, low quality of evidence), reintubation (RR 0.92, 95% CI 0.66 to 1.26, 7 studies, low quality evidence), ICU and long-term weaning unit (LWU) length of stay (MD -7.08 days, 95% CI -16.26 to 2.1, 2 studies, low quality of evidence) and pneumonia (RR 0.67, 95% CI 0.08 to 5.85, 2 studies, low quality of evidence). PS was significantly superior to the TT for successful SBTs (RR 1.09, 95% CI 1.02 to 1.17, 4 studies, moderate quality of evidence). Four studies reported on weaning duration, however we were unable to combined the study data because of differences in how the studies presented their data. One study was at high risk of other bias and four studies were at high risk for detection bias. Three studies reported that the weaning duration was shorter with PS, and in one study the duration was shorter in patients with a TT.



To date, we have found evidence of generally low quality from studies comparing pressure support ventilation (PSV) and with a T-tube. The effects on weaning success, ICU mortality, reintubation, ICU and LWU length of stay, and pneumonia were imprecise. However, PSV was more effective than a T-tube for successful spontaneous breathing trials (SBTs) among patients with simple weaning. Based on the findings of single trials, three studies presented a shorter weaning duration in the group undergoing PS SBT, however a fourth study found a shorter weaning duration with a T-tube.

title: Protocolized vs. non-protocolized weaning for reducing the duration of mechanical ventilation in critically ill adult patients: Cochrane review protocol.
abstract: This paper is a report of the protocol for a review to identify, critically appraise and synthesize the best current evidence supporting the use of weaning protocols compared to non-protocolized practice in liberating patients from mechanical ventilation.



Patients experiencing difficulty in weaning require a longer hospital stay and have higher morbidity and mortality. Consequently, efforts to reduce weaning time are desirable to reduce the duration of ventilation and related complications. Standardized weaning protocols are safe and effective in reducing the time spent on mechanical ventilation.Notwithstanding, the evidence supporting their use in practice is inconsistent. The discordant results of studies may reflect the fact that protocols vary in composition and are implemented in different environments by various healthcare providers.



The objectives of this review are to compare the total duration of mechanical ventilation between patients weaned using protocols vs. non-protocolized practice; to ascertain differences between protocolized and non-protocolized weaning with regards to mortality, adverse events, quality of life, weaning duration, ICU and hospital stay; and to explore variation in outcomes by the type of ICU, the type of protocol and approach to delivering the protocol. We will search the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, ISI Web of Science and LILACS. In addition, we will endeavour to identify unpublished data and contact first authors of studies included in the review to obtain information on unpublished studies or work in progress.



This review will provide much needed direction for healthcare professionals in intensive care in terms of both research and practice.

title: Multicenter implementation of a consensus-developed, evidence-based, spontaneous breathing trial protocol*
abstract: Evidence-based practice recommendations abound, but implementation is often unstructured and poorly audited. We assessed the ability of a peer network to implement an evidence-based best practice protocol and to measure patient outcomes. Consensus definition of spontaneous breathing trial followed by implementation in eight academic medical centers. Six medical, two surgical, and two combined medical/surgical adult intensive care units among eight academic medical centers. Patients initiating mechanical ventilation through an endotracheal tube during a 12-wk interval formed the study population. Adoption and implementation of a common spontaneous breathing trial protocol across multiple intensive care units. Seven hundred five patients had 3,486 safety screens for conducting a spontaneous breathing trial; 2072 (59%) patients failed the safety screen. Another 379 (11%) patients failed a 2-min tolerance screen and 1,122 (34%) patients had a full 30–120 min spontaneous breathing trial performed. Seventy percent of eligible patients were enrolled. Only 55% of passing spontaneous breathing trials resulted in liberation from mechanical ventilatory support before another spontaneous breathing trial was performed. Peer networks can be effective in promoting and implementing evidence-based best practices. Implementation of a best practice (spontaneous breathing trial) may be necessary for, but by itself insufficient to achieve, consistent and timely liberation from ventilator support.

title: Weaning from mechanical ventilation: a model for extubation
abstract: To develop a model able to determine the right time for extubation and to validate its performance.¶Design: A prospective clinical study.¶Setting: 14-bed medical intensive care unit in a university hospital.¶Patients: 101 patients (37 women/64 men) ventilated over more than 48 h (mean 10.4 ± 10.3 days) and considered ready to be weaned by the medical team (February 1996– This study included two series: a development series with 53 patients and a validation series with 48 patients. Before extubation, a weaning test was performed measuring tidal volume (VT), respiratory rate (f), f/VT ratio, minute ventilation, vital capacity (VC) and maximum inspiratory and expiratory pressures (MIP and MEP). The success of extubation was assessed after 48 h. Receiver operating characteristic (ROC) curves allowed the analysis of the discriminating power of each parameter. Threshold values were determined using the Youden's index. To create the best predictive model, we performed a multiple logistic regression analysis. To assess the calibration and the discrimination of the model, the Hosmer-¶Lemeshow goodness-of-fit test and area under ROC curves (AUC) were adopted.¶Measurements and results: In a development series, 60 tests were carried out with 38 successful extubations and 22 extubation failures. The multivariate analysis found three significant variables: VC (threshold value = 635 ml), f/VT ratio (threshold value = 88 breaths/min.l) and MEP (threshold value = 28 cmH2O). The validation cohort included 59 tests (38 successes and 21 failures). The validation series shows a good discrimination (AUC = 0.855 ± 0.059) and calibration (goodness-of-fit test C: p = 0.224) of the model.¶Conclusion: VC together with the ¶f/VT ratio and MEP offer accurate prediction of early extubation.

title: Extubation and the myth of "minimal ventilator settings".
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title: Comparisons of predictive performance of breathing pattern variability measured during T-piece, automatic tube compensation, and pressure support ventilation for weaning intensive care unit patients from mechanical ventilation*
abstract: To investigate the influence of different ventilatory supports on the predictive performance of breathing pattern variability for extubation outcomes in intensive care unit patients. A prospective measurement of retrospectively analyzed breathing pattern variability in a medical center. Sixty-eight consecutive and ready-for-weaning patients were divided into success (n = 45) and failure (n = 23) groups based on their extubation outcomes. Breath-to-breath analyses of peak inspiratory flow, total breath duration, tidal volume, and rapid shallow breathing index were performed for three 30-min periods while patients randomly received T-piece, 100% inspiratory automatic tube compensation with 5 cm H2O positive end-expiratory pressure, and 5 cm H2O pressure support ventilation with 5 cm H2O positive end-expiratory pressure trials. Coefficient of variations and data dispersion (standard descriptor values SD1 and SD2 of the Poincaré plot) were analyzed to serve as breathing pattern variability indices. Under all three trials, breathing pattern variability in extubation failure patients was smaller than in extubation success patients. Compared to the T-piece trial, 100% inspiratory automatic tube compensation with 5 cm H2O positive end-expiratory pressure and 5 cm H2O pressure support ventilation with 5 cm H2O positive end-expiratory pressure decreased the ability of certain breathing pattern variability indices to discriminate extubation success from extubation failure. The areas under the receiver operating characteristic curve of these breathing pattern variability indices were: T-piece (0.73–0.87) > 100% inspiratory automatic tube compensation with 5 cm H2O positive end-expiratory pressure (0.60–0.79) > 5 cm H2O pressure support ventilation with 5 cm H2O positive end-expiratory pressure (0.53–0.76). Analysis of the classification and regression tree indicated that during the T-piece trial, a SD1 of peak inspiratory flow >3.36 L/min defined a group including all extubation success patients. Conversely, the combination of a SD1 of peak inspiratory flow ≤3.36 L/min and a coefficient of variations of rapid shallow breathing index ≤0.23 defined a group of all extubation failure patients. The decision strategies using SD1 of peak inspiratory flow and coefficient of variations of rapid shallow breathing index measured during 100% inspiratory automatic tube compensation with 5 cm H2O positive end-expiratory pressure and 5 cm H2O pressure support ventilation with 5 cm H2O positive end-expiratory pressure trials achieved a less clear separation of extubation failure from extubation success. Since 100% inspiratory automatic tube compensation with 5 cm H2O positive end-expiratory pressure and 5 cm H2O pressure support ventilation with 5 cm H2O positive end-expiratory pressure reduce the predictive performance of breathing pattern variability, breathing pattern variability measurement during the T-piece trial is the best choice for predicting extubation outcome in intensive care unit patients patients.

title: Mechanical ventilator weaning protocols driven by nonphysician health-care professionals: evidence-based clinical practice guidelines.
abstract: Health-care professionals (HCPs) can provide protocol-based care that has a measurable impact on critically ill patients beyond their liberation from mechanical ventilation (MV). Randomized controlled trials have demonstrated that protocols for liberating patients from MV driven by nonphysician HCPs can reduce the duration of MV. The structure and features of protocols should be adapted from published protocols to incorporate patient-specific needs, clinician preferences, and institutional resources. As a general approach, shortly after patients demonstrate that their condition has been stabilized on the ventilator, a spontaneous breathing trial (SBT) is safe to perform and is indicated. Ventilator management strategies for patients who fail a trial of spontaneous breathing include the following: (1) consideration of all remediable factors (such as electrolyte derangements, bronchospasm, malnutrition, patient positioning, and excess secretions) to enhance the prospects of successful liberation from MV; (2) use of a comfortable, safe, and well-monitored mode of MV (such as pressure support ventilation); and (3) repeating a trial of spontaneous breathing on the following day. For patients who pass the SBT, the decision to extubate must be guided by clinical judgment and objective data to minimize the risk of unnecessary reintubations and self-extubations. Protocols should not represent rigid rules but, rather, guides to patient care. Moreover, the protocols may evolve over time as clinical and institutional experience with them increases. Useful protocols aim to safely and efficiently liberate patients from MV, reducing unnecessary or harmful variations in approach.

title: Effect of a nursing-implemented sedation protocol on the duration of mechanical ventilation.
abstract: To compare a practice of protocol-directed sedation during mechanical ventilation implemented by nurses with traditional non-protocol-directed sedation administration.



Randomized, controlled clinical trial.



Medical intensive care unit (19 beds) in an urban teaching hospital.



Patients requiring mechanical ventilation (n = 321).



Patients were randomly assigned to receive either protocol-directed sedation (n = 162) or non-protocol-directed sedation (n = 159).



The median duration of mechanical ventilation was 55.9 hrs (95% confidence interval, 41.0-90.0 hrs) for patients managed with protocol-directed sedation and 117.0 hrs (95% confidence interval, 96.0-155.6 hrs) for patients receiving non-protocol-directed sedation. Kaplan-Meier analysis demonstrated that patients in the protocol-directed sedation group had statistically shorter durations of mechanical ventilation than patients in the non-protocol-directed sedation group (chi-square = 7.00, p = .008, log rank test; chi-square = 8.54, p = .004, Wilcoxon's test; chi-square = 9.18, p = .003, -2 log test). Lengths of stay in the intensive care unit (5.7+/-5.9 days vs. 7.5+/-6.5 days; p = .013) and hospital (14.0+/-17.3 days vs. 19.9+/-24.2 days; p < .001) were also significantly shorter among patients in the protocol-directed sedation group. Among the 132 patients (41.1%) receiving continuous intravenous sedation, those in the protocol-directed sedation group (n = 66) had a significantly shorter duration of continuous intravenous sedation than those in the non-protocol-directed sedation group (n = 66) (3.5+/-4.0 days vs. 5.6+/-6.4 days; p = .003). Patients in the protocol-directed sedation group also had a significantly lower tracheostomy rate compared with patients in the non-protocol-directed sedation group (10 of 162 patients [6.2%] vs. 21 of 159 patients [13.2%], p = .038).



The use of protocol-directed sedation can reduce the duration of mechanical ventilation, the intensive care unit and hospital lengths of stay, and the need for tracheostomy among critically ill patients with acute respiratory failure.

title: The use of continuous i.v. sedation is associated with prolongation of mechanical ventilation.
abstract: To determine whether the use of continuous i.v. sedation is associated with prolongation of the duration of mechanical ventilation.



Prospective observational cohort study.



The medical ICU of Barnes-Jewish Hospital, a university-affiliated urban teaching hospital.



Two hundred forty-two consecutive ICU patients requiring mechanical ventilation.



Patient surveillance and data collection.



The primary outcome measure was the duration of mechanical ventilation. Secondary outcome measures included ICU and hospital lengths of stay, hospital mortality, and acquired organ system derangements. A total of 93 (38.4%) mechanically ventilated patients received continuous i.v. sedation while 149 (61.6%) patients received either bolus administration of i.v. sedation (n=64) or no i.v. sedation (n=85) following intubation. The duration of mechanical ventilation was significantly longer for patients receiving continuous i.v. sedation compared with patients not receiving continuous i.v. sedation (185+/-190 h vs 55.6+/-75.6 h; p<0.001). Similarly, the lengths of intensive care (13.5+/-33.7 days vs 4.8+/-4.1 days; p<0.001) and hospitalization (21.0+/-25.1 days vs 12.8+/-14.1 days; p<0.001) were statistically longer among patients receiving continuous i.v. sedation. Multiple linear regression analysis, adjusting for age, gender, severity of illness, mortality, indication for mechanical ventilation, use of chemical paralysis, presence of a tracheostomy, and the number of acquired organ system derangements, found the adjusted duration of mechanical ventilation to be significantly longer for patients receiving continuous i.v. sedation compared with patients who did not receive continuous i.v. sedation (148 h [95% confidence interval: 121, 175 h] vs 78.7 h [95% confidence interval: 68.9, 88.6 h]; p<0.001).



We conclude from these preliminary observational data that the use of continuous i.v. sedation may be associated with the prolongation of mechanical ventilation. This study suggests that strategies targeted at reducing the use of continuous i.v. sedation could shorten the duration of mechanical ventilation for some patients. Prospective randomized clinical trials, using well-designed sedation guidelines and protocols, are required to determine whether patient-specific outcomes (eg, duration of mechanical ventilation, patient comfort) can be improved compared with conventional sedation practices.

title: Sedation Interruption in Mechanically Ventilated Critically Ill Patients Cared for With a Sedation Protocol A Randomized Controlled Trial
abstract: Sangeeta Mehta, MD Lisa Burry, PharmD Deborah Cook, MD Dean Fergusson, PhD Marilyn Steinberg, RN John Granton, MD Margaret Herridge, MD Niall Ferguson, MD John Devlin, PharmD Maged Tanios, MD Peter Dodek, MD Robert Fowler, MD Karen Burns, MD Michael Jacka, MD Kendiss Olafson, MD Yoanna Skrobik, MD Paul Hébert, MD Elham Sabri, MSc Maureen Meade, MD for the SLEAP Investigators and the Canadian Critical Care Trials Group

title: The Ventilator Discontinuation Process: An Expanding Evidence Base
abstract: The ventilator discontinuation process is an essential component of overall ventilator management. Undue delay leads to excess stay, iatrogenic lung injury, unnecessary sedation, and even higher mortality. On the other hand, premature withdrawal can lead to muscle fatigue, dangerous gas exchange impairment, loss of airway protection, and also a higher mortality. Continued ventilator dependence can be a result of persistent illness or can be a result of poor management. It is obviously important for the clinician to be able to assess both of these issues. An evidence-based task force has recommended regular assessments focusing on the causes of ventilator dependence, regular assessments for evidence of disease stability/reversal, use of regular spontaneous breathing trials (SBTs) as the primary assessment tool for ventilator discontinuation potential, use of separate assessments to evaluate the need for an artificial airway in patients tolerating the SBT, and the use of comfortable, interactive ventilator modes (that do not need to be “weaned”) in between regular SBTs. More recent developments have focused on the importance of linking sedation reduction protocols to ventilator discontinuation protocols. Patients with repeated SBT failures are often considered to require prolonged mechanical ventilation (PMV). These patients often receive tracheostomies and are probably better managed with more gradual reductions in support and gradually lengthened spontaneous breathing periods. PMV patients have a high 1-year mortality, and many may ultimately require lifelong support. This evidence base is growing, but the earlier guidelines are standing the test of time. Indeed, practice patterns are evolving in accordance with them. Nevertheless, there is still room for improvement, and further clinical studies, especially in the patient requiring PMV, are needed.

title: Bedside criteria for discontinuation of mechanical ventilation.
abstract: The purpose of this study was to determine bedside criteria for discontinuation of mechanical ventilation. The resting minute ventilation (MV), maximal voluntary ventilation (MVV) and peak negative pressure on maximal inspiration (PNP) were studied in 100 consecutive patients receiving assisted ventilation. Seventysix patients (Group 1) had MV less than 10 L/min and could double the MV with an MVV maneuver. All Group 1 patients could have mechanical ventilation discontinued. Seventeen patients (Group 2) could not double their resting MV with an MVV maneuver and required further ventilatory assistance. Seven patients (Group 3) could not double their resting MV with an MVV maneuver but did not require further mechanical ventilation. Patients whose PNP was greater than 30 cm H2O less than atmospheric were always able to have mechanical ventilation discontinued. The ease with which these measurements can be performed at the bedside and their high degree of predictability make them useful in acute respiratory care.

title: Predicting 3-day and 7-day outcomes of weaning from mechanical ventilation.
abstract: To determine the correlation of acute physiology and chronic health evaluation (APACHE) II score and various weaning indexes (WIs) with 3- and 7-day weaning outcomes.



Prospective, observational.



The medical ICU of a teaching, urban hospital.



The study included 118 adults referred for weaning from mechanical ventilation (MV). Critical care physicians, critical care nurses, and respiratory care practitioners were asked to predict whether it would take < or =3 days, 4 to 7 days, or > or =8 days to wean each patient from MV. The WIs and APACHE II scores were measured or calculated. The causes of respiratory failure, the duration of MV before initiating weaning assessment, and the 3- and 7-day weaning outcomes were obtained. Significance was set at p<0.05.



The most common causes of respiratory failure were pneumonia (38 cases) and acute exacerbation of COPD (29 cases). Fifty-seven patients (48%) were successfully weaned from MV within 3 days of weaning assessment, and 67 (57%) were weaned within 7 days. The percentages of correct prediction of 3-day weaning outcome by critical care physicians, critical care nurses, and respiratory care practitioners were 64%, 62%, and 59%, respectively; for 7-day weaning outcome, 60%, 64%, and 58%, respectively. The successfully weaned groups had significantly lower APACHE II scores and higher maximal inspiratory pressures than the unsuccessfully weaned (failure) groups. There were no significant differences between the two groups for the remaining indexes, including rapid shallow breathing, dynamic compliance, static compliance, spontaneous respiratory rate, and the ratio of PaO2 to the fraction of inspired oxygen.



The overall severity of illness as assessed by APACHE II score correlates better with 3- and 7-day weaning outcome than the published WIs.

title: Diagnostic accuracy of the rapid shallow breathing index to predict a successful spontaneous breathing trial outcome in mechanically ventilated patients with chronic obstructive pulmonary disease.
abstract: To evaluate the diagnostic accuracy of 2 threshold values (105 breaths per minute [bpm]/L and 130 bpm/L) of the rapid shallow breathing index (RSBI) to predict a successful weaning trial outcome in a homogenous group of patients with chronic obstructive pulmonary disease (COPD).



A consecutive population of patients with COPD who were intubated for hypercapnic respiratory failure during a 2-year period were studied prospectively. RSBI was measured by 2 investigators at minute 5 of the T-piece trial, whereas 2 other physicians evaluated the 30 minute T-piece trial as successful or unsuccessful, according to clinical criteria.



Of 64 patients with COPD (53 male, 11 female) who constituted the study population, 42 patients (35 male, 7 female; aged 70 ± 9.2 years) completed the spontaneous breathing trial (SBT) and remained clinically stable (group 1). The remaining 22 patients (18 male, 4 female; aged 71.9 ± 4.7 years) had to return to ventilatory support by the end of the SBT because of clinical deterioration (group 2). The 2 threshold values that were evaluated had low specificity (38.1% for < 105 bpm/L and 66.7% for < 130 bpm/L), low sensitivity (63.6% for < 105 bpm/L and 54.5% for < 130 bpm/L), and low diagnostic accuracy (46.8% for < 105 bpm/L and 65.6% for < 130 bpm/L) in predicting a successful T-piece trial outcome.



RSBI measured early during an SBT cannot accurately predict the successful outcome of a T-piece trial in a homogenous population of patients with COPD.

title: Tidal volume maintenance during weaning with pressure support.
abstract: Ventilation was measured in 31 difficult-to-wean patients while pressure support (PS) was reduced by 5 cm H2O every 20 min. Weaning had to be aborted in 14 of 31 patients (Group F) because they met predefined distress criteria. The remaining 17 patients who were able to complete the "weaning test" (Group S) had larger static respiratory compliances (Cstat = 0.08 +/- 0.02 versus 0.05 +/- 0.01 L/cm H2O, p < or = 0.05) and a lower dead space to tidal volume ratio (0.55 +/- 0.05 versus 0.64 +/- 0.06, p < or = 0.05). Group S patients had a larger tidal volume (VT) than did those of Group F at most PS settings. The groups differed with respect to VT maintenance during PS withdrawal (p < 0.01). In Group S, VT fell exponentially with machine support and stabilized at PS levels between 5 and 10 cm H2O. In contrast, Group F patients defended VT at higher PS settings but were unable to maintain VT during distress. Ventilatory response parameters such as the rapid shallow breathing index were of limited value in predicting weaning outcome and yielded receiver operator curve area values between 0.66 and 0.82 over the range of PS settings tested. We conclude that the gradual withdrawal of machine support does not facilitate the recognition of impending respiratory failure.

title: Do heart and respiratory rate variability improve prediction of extubation outcomes in critically ill patients?
abstract: IntroductionProlonged ventilation and failed extubation are associated with increased harm and cost. The added value of heart and respiratory rate variability (HRV and RRV) during spontaneous breathing trials (SBTs) to predict extubation failure remains unknown.MethodsWe enrolled 721 patients in a multicenter (12 sites), prospective, observational study, evaluating clinical estimates of risk of extubation failure, physiologic measures recorded during SBTs, HRV and RRV recorded before and during the last SBT prior to extubation, and extubation outcomes. We excluded 287 patients because of protocol or technical violations, or poor data quality. Measures of variability (97 HRV, 82 RRV) were calculated from electrocardiogram and capnography waveforms followed by automated cleaning and variability analysis using Continuous Individualized Multiorgan Variability Analysis (CIMVA™) software. Repeated randomized subsampling with training, validation, and testing were used to derive and compare predictive models.ResultsOf 434 patients with high-quality data, 51 (12%) failed extubation. Two HRV and eight RRV measures showed statistically significant association with extubation failure (P <0.0041, 5% false discovery rate). An ensemble average of five univariate logistic regression models using RRV during SBT, yielding a probability of extubation failure (called WAVE score), demonstrated optimal predictive capacity. With repeated random subsampling and testing, the model showed mean receiver operating characteristic area under the curve (ROC AUC) of 0.69, higher than heart rate (0.51), rapid shallow breathing index (RBSI; 0.61) and respiratory rate (0.63). After deriving a WAVE model based on all data, training-set performance demonstrated that the model increased its predictive power when applied to patients conventionally considered high risk: a WAVE score >0.5 in patients with RSBI >105 and perceived high risk of failure yielded a fold increase in risk of extubation failure of 3.0 (95% confidence interval (CI) 1.2 to 5.2) and 3.5 (95% CI 1.9 to 5.4), respectively.ConclusionsAltered HRV and RRV (during the SBT prior to extubation) are significantly associated with extubation failure. A predictive model using RRV during the last SBT provided optimal accuracy of prediction in all patients, with improved accuracy when combined with clinical impression or RSBI. This model requires a validation cohort to evaluate accuracy and generalizability.

title: Extubation outcome after spontaneous breathing trials with T-tube or pressure support ventilation. The Spanish Lung Failure Collaborative Group.
abstract: A 2-h T-tube trial of spontaneous breathing was used in selecting patients ready for extubation and discontinuation of mechanical ventilation. However, some doubt remains as to whether it is the most appropriate method of performing a spontaneous breathing trial. We carried out a prospective, randomized, multicenter study involving patients who had received mechanical ventilation for more than 48 h and who were considered by their physicians to be ready for weaning according to clinical criteria and standard weaning parameters. Patients were randomly assigned to undergo a 2-h trial of spontaneous breathing in one of two ways: with a T-tube system or with pressure support ventilation of 7 cm H2O. If a patient had signs of poor tolerance at any time during the trial, mechanical ventilation was reinstituted. Patients without these features at the end of the trial were extubated. Of the 246 patients assigned to the T-tube group, 192 successfully completed the trial and were extubated; 36 of them required reintubation. Of the 238 patients in the group receiving pressure support ventilation, 205 were extubated and 38 of them required reintubation. The percentage of patients who remained extubated after 48 h was not different between the two groups (63% T-tube, 70% pressure support ventilation, p = 0.14). The percentage of patients falling the trial was significantly higher when the T-tube was used (22 versus 14%, p = 0.03). Clinical evolution during the trial was not different in patients reintubated and successfully extubated. ICU mortality among reintubated patients was significantly higher than in successfully extubated patients (27 versus 2.6%, p < 0.001). Spontaneous breathing trials with pressure support or T-tube are suitable methods for successful discontinuation of ventilator support in patients without problems to resume spontaneous breathing.

title: Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial
abstract: Approaches to removal of sedation and mechanical ventilation for critically ill patients vary widely. Our aim was to assess a protocol that paired spontaneous awakening trials (SATs)-ie, daily interruption of sedatives-with spontaneous breathing trials (SBTs).



In four tertiary-care hospitals, we randomly assigned 336 mechanically ventilated patients in intensive care to management with a daily SAT followed by an SBT (intervention group; n=168) or with sedation per usual care plus a daily SBT (control group; n=168). The primary endpoint was time breathing without assistance. Data were analysed by intention to treat. 
One patient in the intervention group did not begin their assigned treatment protocol because of withdrawal of consent and thus was excluded from analyses and lost to follow-up. Seven patients in the control group discontinued their assigned protocol, and two of these patients were lost to follow-up. Patients in the intervention group spent more days breathing without assistance during the 28-day study period than did those in the control group (14.7 days vs 11.6 days; mean difference 3.1 days, 95% CI 0.7 to 5.6; p=0.02) and were discharged from intensive care (median time in intensive care 9.1 days vs 12.9 days; p=0.01) and the hospital earlier (median time in the hospital 14.9 days vs 19.2 days; p=0.04). More patients in the intervention group self-extubated than in the control group (16 patients vs six patients; 6.0% difference, 95% CI 0.6% to 11.8%; p=0.03), but the number of patients who required reintubation after self-extubation was similar (five patients vs three patients; 1.2% difference, 95% CI -5.2% to 2.5%; p=0.47), as were total reintubation rates (13.8%vs 12.5%; 1.3% difference, 95% CI -8.6% to 6.1%; p=0.73). At any instant during the year after enrolment, patients in the intervention group were less likely to die than were patients in the control group (HR 0.68, 95% CI 0.50 to 0.92; p=0.01). For every seven patients treated with the intervention, one life was saved (number needed to treat was 7.4, 95% CI 4.2 to 35.5).



Our results suggest that a wake up and breathe protocol that pairs daily spontaneous awakening trials (ie, interruption of sedatives) with daily spontaneous breathing trials results in better outcomes for mechanically ventilated patients in intensive care than current standard approaches and should become routine practice.

title: Predictors of extubation outcome in patients who have successfully completed a spontaneous breathing trial.
abstract: After patients recovering from respiratory failure have successfully completed a spontaneous breathing trial (SBT), clinicians must determine whether an artificial airway is still required. We hypothesized that cough strength and the magnitude of endotracheal secretions affect extubation outcomes.



We conducted a prospective study of 91 adult patients treated in medical-cardiac ICUs who were recovering from respiratory failure, had successfully completed an SBT, and were about to be extubated. A number of demographic and physiologic parameters were recorded with the patient receiving full ventilatory support and during the SBT, just prior to extubation. Cough strength on command was measured with a semiobjective scale of 0 to 5, and the magnitude of endotracheal secretions was measured as none, mild, moderate, or abundant by a single observer. In addition, patients were asked to cough onto a white card held 1 to 2 cm from the endotracheal tube; if secretions were propelled onto the card, it was termed a positive white card test (WCT) result. All patients were then extubated from T-piece or continuous positive airway pressure breathing trials. If 72 h elapsed and patients did not require reintubation, they were defined as successfully extubated.



Ninety-one patients with a mean (+/- SE) age of 65.2 +/- 1.6 years, ICU admission APACHE (acute physiology and chronic health evaluation) II score of 17.7 +/- 0.7, and duration of mechanical ventilation of 5.0 +/- 0.5 days were studied over 100 extubations. Sixteen patients could not be extubated, and 2 patients underwent two unsuccessful extubation attempts, for a total of 18 unsuccessful extubations. Age, severity of illness, duration of mechanical ventilation, oxygenation, rapid shallow breathing index, and vital signs during SBTs did not differ between patients with successful extubations vs patients with unsuccessful extubations. The WCT result was highly correlated with cough strength. Patients with weak (grade 0 to 2) coughs were four times as likely to have unsuccessful extubations, compared to those with moderate-to-strong (grade 3 to 5) coughs (risk ratio [RR], 4.0; 95% confidence interval [CI],1.8 to 8.9). Patients with moderate-to-abundant secretions were more than eight times as times as likely to have unsuccessful extubations as those with no or mild secretions (RR, 8.7; 95% CI, 2.1 to 35.7). Patients with negative WCT results were three times as likely to have unsuccessful extubations as those with positive WCT results (RR, 3.0; 95% CI, 1.3 to 6.7). Poor cough strength and endotracheal secretions were synergistic in predicting extubation failure (Rothman synergy index, 3.7; RR, 31.9; 95% CI, 4.5 to 225.3). Patients with PaO(2)/fraction of inspired oxygen (P:F) ratios of 120 to 200 (receiving mechanical ventilation) were not less likely to be successfully extubated than those with P:F ratios of > 200, but those with hemoglobin levels < or = 10 g/dL were more than five times as likely to have unsuccessful extubations as those with hemoglobin levels > 10 g/dL.



After patients recovering from respiratory failure have successfully completed an SBT, factors affecting airway competence, such as cough strength and amount of endotracheal secretions, may be important predictors of extubation outcomes. Also, a majority (89%) of medically ill patients with P:F ratios of 120 to 200 (four of five patients with P:F ratios from 120 to 150), values sometimes used to preclude weaning, were extubated successfully.

title: Risk factors for extubation failure in patients following a successful spontaneous breathing trial.
abstract: To assess the factors associated with reintubation in patients who had successfully passed a spontaneous breathing trial.



We used logistic regression and recursive partitioning analyses of prospectively collected clinical data from adults admitted to ICUs of 37 hospitals in eight countries, who had undergone invasive mechanical ventilation for > 48 h and were deemed ready for extubation.



Extubation failure occurred in 121 of the 900 patients (13.4%). The logistic regression analysis identified the following associations with reintubation: rapid shallow breathing index (RSBI) [odds ratio (OR), 1.009 per unit; 95% confidence interval (CI), 1.003 to 1.015]; positive fluid balance (OR, 1.70; 95% CI, 1.15 to 2.53); and pneumonia as the reason for initiating mechanical ventilation (OR, 1.77; 95% CI, 1.10 to 2.84). The recursive partitioning analysis allowed the separation of patients into different risk groups for extubation failure: (1) RSBI of > 57 breaths/L/min and positive fluid balance (OR, 3.0; 95% CI, 1.8 to 4.8); (2) RSBI of < 57 breaths/L/min and pneumonia as reason for mechanical ventilation (OR, 2.0; 95% CI, 1.1 to 3.6); (3) RSBI of > 57 breaths/L/min and negative fluid balance (OR, 1.4; 95% CI, 0.8 to 2.5); and (4) RSBI of < 57 breaths/L/min (OR, 1 ).



Among routinely measured clinical variables, RSBI, positive fluid balance 24 h prior to extubation, and pneumonia at the initiation of ventilation were the best predictors of extubation failure. However, the combined predictive ability of these variables was weak.

title: Protocol weaning of mechanical ventilation in medical and surgical patients by respiratory care practitioners and nurses: effect on weaning time and incidence of ventilator-associated pneumonia.
abstract: (1) To determine the effect of a single ventilator management protocol (VMP) used in medical and surgical ICUs on the duration of mechanical ventilation. (2) To determine the effect of a VMP on the incidence of ventilator-associated pneumonia (VAP).



Prospective, randomized, controlled study.



: University medical center.



Three hundred eighty-five patients receiving mechanical ventilation between June 1997 and May 1998.



A respiratory care practitioner- and registered nurse-driven VMP.



Intervention and control groups were comparable with respect to age, sex, severity of illness and injury, and duration of respiratory failure at the time of randomization. The duration of mechanical ventilation for patients was decreased from a median of 124 h for the control group to 68 h in the VMP group (p = 0.0001). Thirty-one total instances of VAP were noted. Twelve patients in the surgical control group had VAP, compared with 5 in the surgical VMP group (p = 0.061). The impact of the VMP on VAP frequency was less for medical patients. Mortality and ventilator discontinuation failure rates were similar between control and VMP groups.



A VMP designed for multidisciplinary use was effective in reducing duration of mechanical ventilatory support without any adverse effects on patient outcome. The VMP was also associated with a decrease in incidence of VAP in trauma patients. These results, in conjunction with prior studies, suggest that VMPs are highly effective means of improving care, even in university ICUs.

title: Improved extubation rates and earlier liberation from mechanical ventilation with implementation of a daily spontaneous-breathing trial protocol.
abstract: Daily spontaneous-breathing trials (SBTs) are promulgated as the best method for assessing readiness for discontinuation of mechanical ventilation. SBT protocols have also been shown to improve outcomes as opposed to wild-type implementation of daily SBT recommendations. Here we determine whether implementation of a mandatory, protocol-driven daily SBT on all ventilated patients in the ICU improves extubation rates and accelerates liberation from mechanical ventilation.



A daily 30-minute SBT protocol was introduced into an academic surgical ICU in July 2005 and followed through September 2006. Decisions about next steps (continued mechanical support versus liberation) after each trial were recorded. Owing to the low liberation rate, physicians began (in January 2006) recording the reasons for continuing mechanical ventilation after a passing SBT. Differences in patient outcomes were compared for the first and last 8 weeks of the study period, corresponding to similar times in the academic and calendar years.



Four hundred eighty-eight patients experienced 547 mechanical ventilation episodes from July 2005 to September 2006. A total of 2,835 safety evaluations for SBTs were completed. Rate of extubations of passing patients after the first 8 weeks of implementation (n = 73 patients) was 27% (35 extubations of 131 passed trials). This rate improved in the last 8 weeks to 42% (42 of 101) (p < 0.02) (n = 57 patients). Reintubation rate was similar at 6% for the first 8 weeks and 8% for the final 8 weeks (p = 0.65), including self-extubations.



Implementation of a daily SBT protocol resulted in improvement of extubation rates during the year of implementation without a change in the reintubation rate. Requesting that physicians enumerate reasons for continuing mechanical ventilation in the face of a passing breathing trial was associated with a sustained improvement in extubation rate.