The prognostic significance of passing a daily screen of weaning parameters

Co-ordinated multidisciplinary intervention to reduce time to successful extubation for children on mechanical ventilation: the SANDWICH cluster stepped-wedge RCT

BACKGROUND

Daily assessment of patient readiness for liberation from invasive mechanical ventilation can reduce the duration of ventilation. However, there is uncertainty about the effectiveness of this in a paediatric population.

OBJECTIVES

To determine the effect of a ventilation liberation intervention in critically ill children who are anticipated to have a prolonged duration of mechanical ventilation (primary objective) and in all children (secondary objective).

DESIGN

A pragmatic, stepped-wedge, cluster randomised trial with economic and process evaluations.

SETTING

Paediatric intensive care units in the UK.

PARTICIPANTS

Invasively mechanically ventilated children (aged < 16 years).

INTERVENTIONS

The intervention incorporated co-ordinated multidisciplinary care, patient-relevant sedation plans linked to sedation assessment, assessment of ventilation parameters with a higher than usual trigger for undertaking an extubation readiness test and a spontaneous breathing trial on low levels of respiratory support to test extubation readiness. The comparator was usual care. Hospital sites were randomised sequentially to transition from control to intervention and were non-blinded.

MAIN OUTCOME MEASURES

The primary outcome measure was the duration of invasive mechanical ventilation until the first successful extubation. The secondary outcome measures were successful extubation, unplanned extubation and reintubation, post-extubation use of non-invasive ventilation, tracheostomy, post-extubation stridor, adverse events, length of intensive care and hospital stay, mortality and cost per respiratory complication avoided at 28 days.

RESULTS

The trial included 10,495 patient admissions from 18 paediatric intensive care units from 5 February 2018 to 14 October 2019. In children with anticipated prolonged ventilation (n = 8843 admissions: control, n = 4155; intervention, n = 4688), the intervention resulted in a significantly shorter time to successful extubation [cluster and time-adjusted median difference -6.1 hours (interquartile range -8.2 to -5.3 hours); adjusted hazard ratio 1.11, 95% confidence interval 1.02 to 1.20; p = 0.02] and a higher incidence of successful extubation (adjusted relative risk 1.01, 95% confidence interval 1.00 to 1.02; p = 0.03) and unplanned extubation (adjusted relative risk 1.62, 95% confidence interval 1.05 to 2.51; p = 0.03), but not reintubation (adjusted relative risk 1.10, 95% confidence interval 0.89 to 1.36; p = 0.38). In the intervention period, the use of post-extubation non-invasive ventilation was significantly higher (adjusted relative risk 1.22, 95% confidence interval 1.01 to 1.49; p = 0.04), with no evidence of a difference in intensive care length of stay or other harms, but hospital length of stay was longer (adjusted hazard ratio 0.89, 95% confidence interval 0.81 to 0.97; p = 0.01). Findings for all children were broadly similar. The control period was associated with lower, but not statistically significantly lower, total costs (cost difference, mean £929.05, 95% confidence interval -£516.54 to £2374.64) and significantly fewer respiratory complications avoided (mean difference -0.10, 95% confidence interval -0.16 to -0.03).

LIMITATIONS

The unblinded intervention assignment may have resulted in performance or detection bias. It was not possible to determine which components were primarily responsible for the observed effect. Treatment effect in a more homogeneous group remains to be determined.

CONCLUSIONS

The intervention resulted in a statistically significant small reduction in time to first successful extubation; thus, the clinical importance of the effect size is uncertain.

FUTURE WORK

Future work should explore intervention sustainability and effects of the intervention in other paediatric populations.

TRIAL REGISTRATION

This trial is registered as ISRCTN16998143.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 18. See the NIHR Journals Library website for further project information.

Liberation from Invasive Mechanical Ventilation with Continued Receipt of Vasopressor Infusions

RATIONALE

Weaning protocols for discontinuation of invasive mechanical ventilation often mandate resolution of shock. Whether extubation while receiving vasopressors is associated with harm is uncertain.

OBJECTIVES

To examine whether extubation while still receiving vasopressors is associated with worse outcomes.

METHODS

We performed a retrospective cohort study of adults in Calgary ICUs who received vasopressors with invasive mechanical ventilation and an extubation attempt. The primary exposure was continued vasopressor use at extubation. The primary outcome was reintubation within 96-hours. Secondary outcomes included in-hospital mortality and ICU/hospital length of stay (LOS). We assessed associations of vasopressor use at extubation with outcomes using multivariable competing-risk (reintubation/LOS) and Cox proportional-hazards (mortality) models.

MEASUREMENTS AND MAIN RESULTS

Of 6140 patients who received invasive mechanical ventilation while on vasopressors, 721 (11.7%) were extubated while receiving vasopressors and 5419 (88.3%) after discontinuation. Extubation on vasopressors was not, in aggregate, significantly associated with an increased hazard of reintubation (sub-hazard ratio, 1.81 [95% CI: 0.91 - 3.61], P=0.09). Both mortality (HR 1.22 [1.02-1.47], P=0.03) and time to hospital discharge (SHR for remaining hospitalized 0.78 [0.68-0.91], P<0.01) were increased. Extubation on high-dose vasopressors (>0.1 µg/kg/min) was associated with a greater hazard of reintubation (SHR 2.25 [1.01-4.98], P=0.046) compared to extubation after vasopressor discontinuation. Meanwhile, extubation on low-dose vasopressors (≤0.1 µg/kg/min) was associated with a lower mortality (HR 0.69 [0.51-0.91], P=0.01) and a shorter ICU LOS (SHR 1.34 [1.09-1.65], P<0.01), but no difference in reintubation or hospital LOS as compared to those weaned off vasopressors.

CONCLUSIONS

Extubation while receiving high-dose but not low-dose vasopressors was associated with an increased risk of reintubation.

Diaphragm ultrasound as a better predictor of successful extubation from mechanical ventilation than rapid shallow breathing index

Background

In 3%–19% of patients, reintubation is needed 48–72 hours following extubation, which increases intensive care unit (ICU) morbidity, mortality, and expenses. Extubation failure is frequently caused by diaphragm dysfunction. Ultrasonography can be used to determine the mobility and thickness of the diaphragm. This study looked at the role of diaphragm excursion (DE) and thickening fraction in predicting successful extubation from mechanical ventilation.

Methods

Thirty-one patients were extubated with the advice of an ICU consultant using the ICU weaning regimen and diaphragm ultrasonography was performed. Ultrasound DE and thickening fraction were measured three times: at the commencement of the T-piece experiment, at 10 minutes, and immediately before extubation. All patients' parameters were monitored for 48 hours after extubation. Rapid shallow breathing index (RSBI) was also measured at the same time.

Results

Successful extubation was significantly correlated with DE (P<0.001). Receiver curve analysis for DE to predict successful extubation revealed good properties (area under the curve [AUC], 0.83; P<0.001); sensitivity, 77.8%; specificity, 84.6%; positive predictive value (PPV), 84.6 %; negative predictive value (NPV), 73.3% while cut-off value, 11.43 mm. Diaphragm thickening fraction (DTF) also revealed moderate curve properties (AUC, 0.69; P=0.06); sensitivity, 61.1%; specificity, 84.6%; PPV, 87.5%; NPV, 61.1% with cut-off value 22.33% although former one was slightly better. RSBI could not reach good receiver operating characteristic value at cut-off points 100 breaths/min/L (AUC, 0.58; P=0.47); sensitivity, 66.7%; specificity, 53.8%; PPV, 66.7%; NPV, 53.8%).

Conclusions

To decrease the rate of reintubation, DE and DTF are better indicators of successful extubation. DE outperforms DTF.

Diaphragm ultrasound to predict weaning outcome: systematic review and meta-analysis

Proper timing for discontinuation of mechanical ventilation is of great importance, especially in patients with previous weaning failures. Different indices obtained by ultra-sonographic evaluation of the diaphragm muscle have improved determination of weaning success. The aim of the present systematic review was to evaluate and compare the accuracy of the diagnostic indices obtained by ultrasonographic examination, including diaphragm thickening fraction (DTF), diaphragmatic excursion (DE) and the rapid shallow breathing index (RSBI). A systematic literature search (Web of Science, MEDLINE, Embase and Google Scholar) was performed to identify original articles assessing diaphragm muscle features including excursion and thickening fraction. A total of 2738 citations were retrieved initially; available data of 19 cohort studies (1114 patients overall) were included in the meta-analysis, subdivided into groups based on the ultrasonographic examination type. Our results showed the superiority of the diagnostic accuracy of the DTF in comparison to the DE and the RSBI. Data on the combination of the different indices are limited. Diaphragmatic ultrasound is a cheap and feasible tool for diaphragm function evaluation. Moreover, DTF in the assessment of weaning outcome provides more promising outcomes, which should be evaluated more meti-culously in future randomised trials.

Cardiopulmonary coupling indices to assess weaning readiness from mechanical ventilation

The ideal moment to withdraw respiratory supply of patients under Mechanical Ventilation at Intensive Care Units (ICU), is not easy to be determined for clinicians. Although the Spontaneous Breathing Trial (SBT) provides a measure of the patients' readiness, there is still around 15-20% of predictive failure rate. This work is a proof of concept focused on adding new value to the prediction of the weaning outcome. Heart Rate Variability (HRV) and Cardiopulmonary Coupling (CPC) methods are evaluated as new complementary estimates to assess weaning readiness. The CPC is related to how the mechanisms regulating respiration and cardiac pumping are working simultaneously, and it is defined from HRV in combination with respiratory information. Three different techniques are used to estimate the CPC, including Time-Frequency Coherence, Dynamic Mutual Information and Orthogonal Subspace Projections. The cohort study includes 22 patients in pressure support ventilation, ready to undergo the SBT, analysed in the 24 h previous to the SBT. Of these, 13 had a successful weaning and 9 failed the SBT or needed reintubation -being both considered as failed weaning. Results illustrate that traditional variables such as heart rate, respiratory frequency, and the parameters derived from HRV do not differ in patients with successful or failed weaning. Results revealed that HRV parameters can vary considerably depending on the time at which they are measured. This fact could be attributed to circadian rhythms, having a strong influence on HRV values. On the contrary, significant statistical differences are found in the proposed CPC parameters when comparing the values of the two groups, and throughout the whole recordings. In addition, differences are greater at night, probably because patients with failed weaning might be experiencing more respiratory episodes, e.g. apneas during the night, which is directly related to a reduced respiratory sinus arrhythmia. Therefore, results suggest that the traditional measures could be used in combination with the proposed CPC biomarkers to improve weaning readiness.

Effect of a Sedation and Ventilator Liberation Protocol vs Usual Care on Duration of Invasive Mechanical Ventilation in Pediatric Intensive Care Units: A Randomized Clinical Trial

IMPORTANCE

There is limited evidence on the optimal strategy for liberating infants and children from invasive mechanical ventilation in the pediatric intensive care unit.

OBJECTIVE

To determine if a sedation and ventilator liberation protocol intervention reduces the duration of invasive mechanical ventilation in infants and children anticipated to require prolonged mechanical ventilation.

DESIGN, SETTING, AND PARTICIPANTS

A pragmatic multicenter, stepped-wedge, cluster randomized clinical trial was conducted that included 17 hospital sites (18 pediatric intensive care units) in the UK sequentially randomized from usual care to the protocol intervention. From February 2018 to October 2019, 8843 critically ill infants and children anticipated to require prolonged mechanical ventilation were recruited. The last date of follow-up was November 11, 2019.

INTERVENTIONS

Pediatric intensive care units provided usual care (n = 4155 infants and children) or a sedation and ventilator liberation protocol intervention (n = 4688 infants and children) that consisted of assessment of sedation level, daily screening for readiness to undertake a spontaneous breathing trial, a spontaneous breathing trial to test ventilator liberation potential, and daily rounds to review sedation and readiness screening and set patient-relevant targets.

MAIN OUTCOMES AND MEASURES

The primary outcome was the duration of invasive mechanical ventilation from initiation of ventilation until the first successful extubation. The primary estimate of the treatment effect was a hazard ratio (with a 95% CI) adjusted for calendar time and cluster (hospital site) for infants and children anticipated to require prolonged mechanical ventilation.

RESULTS

There were a total of 8843 infants and children (median age, 8 months [interquartile range, 1 to 46 months]; 42% were female) who completed the trial. There was a significantly shorter median time to successful extubation for the protocol intervention compared with usual care (64.8 hours vs 66.2 hours, respectively; adjusted median difference, -6.1 hours [interquartile range, -8.2 to -5.3 hours]; adjusted hazard ratio, 1.11 [95% CI, 1.02 to 1.20], P = .02). The serious adverse event of hypoxia occurred in 9 (0.2%) infants and children for the protocol intervention vs 11 (0.3%) for usual care; nonvascular device dislodgement occurred in 2 (0.04%) vs 7 (0.1%), respectively.

CONCLUSIONS AND RELEVANCE

Among infants and children anticipated to require prolonged mechanical ventilation, a sedation and ventilator liberation protocol intervention compared with usual care resulted in a statistically significant reduction in time to first successful extubation. However, the clinical importance of the effect size is uncertain.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN16998143.

Weaning patients with obesity from ventilatory support

PURPOSE OF REVIEW

Obesity prevalence is increasing in most countries in the world. In the United States, 42% of the population is obese (body mass index (BMI) > 30) and 9.2% is obese class III (BMI > 40). One of the greatest challenges in critically ill patients with obesity is the optimization of mechanical ventilation. The goal of this review is to describe respiratory physiologic changes in patients with obesity and discuss possible mechanical ventilation strategies to improve respiratory function.

RECENT FINDINGS

Individualized mechanical ventilation based on respiratory physiology after a decremental positive end-expiratory pressure (PEEP) trial improves oxygenation and respiratory mechanics. In a recent study, mortality of patients with respiratory failure and obesity was reduced by about 50% when mechanical ventilation was associated with the use of esophageal manometry and electrical impedance tomography (EIT).

SUMMARY

Obesity greatly alters the respiratory system mechanics causing atelectasis and prolonged duration of mechanical ventilation. At present, novel strategies to ventilate patients with obesity based on individual respiratory physiology showed to be superior to those based on standard universal tables of mechanical ventilation. Esophageal manometry and EIT are essential tools to systematically assess respiratory system mechanics, safely adjust relatively high levels of PEEP, and improve chances for successful weaning.

Ventilator Weaning and Discontinuation Practices for Critically Ill Patients

IMPORTANCE

Although most critically ill patients receive invasive mechanical ventilation (IMV), few studies have characterized how IMV is discontinued in practice.

OBJECTIVE

To describe practice variation in IMV discontinuation internationally, associations between initial discontinuation events and outcomes, and factors associated with the use of select discontinuation strategies and failed initial spontaneous breathing trials (SBTs).

DESIGN, SETTING, AND PARTICIPANTS

Prospective, multinational, observational study of critically ill adults who received IMV for at least 24 hours from 142 intensive care units (ICUs) in 19 countries within 6 regions (27 in Canada, 23 in India, 22 in the UK, 26 in Europe, 21 in Australia/New Zealand, and 23 in the US).

EXPOSURES

Receiving IMV.

MAIN OUTCOMES AND MEASURES

Primary analyses characterized types of initial IMV discontinuation events (extubation, SBT, or tracheostomy) and associations with clinical outcomes (including duration of ventilation, ICU and hospital mortality, and ICU and hospital length of stay). Secondary analyses examined the associations between SBT outcome and SBT timing and clinical outcomes.

RESULTS

Among 1868 patients (median [interquartile range] age, 61.8 [48.9-73.1] years; 1173 [62.8%] men) 424 (22.7%) underwent direct extubation, 930 (49.8%) had an initial SBT (761 [81.8%] successful), 150 (8.0%) underwent direct tracheostomy, and 364 (19.5%) died before a weaning attempt. Across regions, there was variation in the use of written directives to guide care, daily screening, SBT techniques, ventilator modes, and the roles played by clinicians involved in weaning. Compared with initial direct extubation, patients who had an initial SBT had higher ICU mortality (20 [4.7%] vs 96 [10.3%]; absolute difference, 5.6% [95% CI, 2.6%-8.6%]), longer duration of ventilation (median of 2.9 vs 4.1 days; absolute difference, 1.2 days [95% CI, 0.7-1.6]), and longer ICU stay (median of 6.7 vs 8.1 days; absolute difference, 1.4 days [95% CI, 0.8-2.4]). Patients whose initial SBT failed (vs passed) had higher ICU mortality (29 [17.2%] vs 67 [8.8%]; absolute difference, 8.4% [95% CI, 2.0%-14.7%]), longer duration of ventilation (median of 6.1 vs 3.5 days; absolute difference, 2.6 days [95% CI, 1.6-3.6]), and longer ICU stay (median of 10.6 vs 7.7 days; absolute difference, 2.8 days [95% CI, 1.1-5.2]). Compared with patients who underwent early initial SBTs, patients who underwent late initial SBTs (>2.3 days after intubation) had longer duration of ventilation (median of 2.1 vs 6.1 days; absolute difference, 4.0 days [95% CI, 3.7-4.5]), longer ICU stay (median of 5.9 vs 10.8 days; absolute difference, 4.9 days [95% CI, 4.0-6.3]), and longer hospital stay (median of 14.3 vs 22.8 days; absolute difference, 8.5 days [95% CI, 6.0-11.0]).

CONCLUSIONS AND RELEVANCE

In this observational study of invasive mechanical ventilation discontinuation in 142 ICUs in Canada, India, the UK, Europe, Australia/New Zealand, and the US from 2013 to 2016, weaning practices varied internationally.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03955874.

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.

The Utility of Diaphragm Ultrasound in Reducing Time to Extubation

Purpose

Prediction of optimal timing for extubation of mechanically ventilated patients is challenging. Ultrasound measures of diaphragm thickness or diaphragm dome excursion have been used to aid in predicting extubation success or failure. The aim of this study was to determine if incorporating results of diaphragm ultrasound into usual ICU care would shorten the time to extubation.

Methods

We performed a prospective, randomized, controlled study at three Brown University teaching hospitals. Included subjects underwent block randomization to either usual care (Control) or usual care enhanced with ultrasound measurements of the diaphragm (Intervention). The primary outcome was the time to extubation after ultrasound, and the secondary outcome was the total days on the ventilator. Only intensivists in the Intervention group would have the ultrasound information on the likelihood of successful extubation available to incorporate with traditional clinical and physiologic measures to determine the timing of extubation.

Results

A total of 32 subjects were studied; 15 were randomized into the Control group and 17 into the Intervention group. The time from ultrasound to extubation was significantly reduced in the Intervention group compared to the Control group in patients with a ∆tdi% ≥ 30% (4.8 ± 8.4 vs 35.0 ± 41.0 h, p = 0.04). The time from ultrasound to extubation was shorter in subjects with a normally functioning diaphragm (∆tdi% ≥ 30%) compared to those with diaphragm dysfunction (∆tdi% < 30%) (23.2 ± 35.2 vs 57.3 ± 52.0 h p = 0.046). When combining the Intervention and Control groups, a value of ∆tdi% ≥ 30% for extubation success at 24 h provided a sensitivity, specificity, PPV and NPV of 90.9%, 86.7%, 90.9%, and 86.7%, respectively.

Conclusions

Diaphragm ultrasound evaluation of ∆tdi% aids in reducing time to extubation.

Extubating the Neurocritical Care Patient: A Spontaneous Breathing Trial Algorithmic Approach

BACKGROUND

Delaying extubation in neurologically impaired patients otherwise ready for extubation is a source for significant morbidity, mortality, and costs. There is no consensus to suggest one spontaneous breathing trial (SBT) over another in predicting extubation success. We studied an algorithm using zero pressure support and zero positive end-expiratory pressure (ZEEP) SBT followed by 5-cm H₂O pressure support and 5-cm H₂O positive end-expiratory pressure (i.e., 5/5) SBT in those who failed ZEEP SBT.

METHODS

This is a retrospective analysis of intubated patients in a neurosciences intensive care unit. All eligible patients were initially challenged with ZEEP SBT. If failed, a 5/5 SBT was immediately performed. If passed either the ZEEP SBT or the subsequent 5/5 SBT, patients were liberated from mechanical ventilation.

RESULTS

In total, 108 adult patients were included. The majority of patients were successfully liberated from mechanical ventilation using ZEEP SBT alone (82.4%; p = 0.0007). Fifteen (13.8%) patients failed ZEEP SBT but immediately passed 5/5 SBT (p = 0.0005). One patient (0.93%) required reintubation. We found high sensitivity of this extubation algorithm (100; 95% CI 95.94-100%) but poor specificity (6.67; 95% CI 0.17-31.95%).

CONCLUSION

This study showed that the majority of patients could be successfully liberated from mechanical ventilation after a ZEEP SBT. In those who failed, a 5/5 SBT increased the successful liberation from mechanical ventilation.

Feasibility of a protocol to wean patients from continuous renal replacement therapy: A retrospective pilot observation

PURPOSE

To evaluate the feasibility of a protocol-based algorithm to wean acute kidney injury (AKI) patients from continuous renal replacement therapy (CRRT).

METHODS

The protocol was introduced on one of two similarly equipped ICUs, while on the other (reference) ICU, CRRT discontinuation was based on clinical judgement. Patients were allocated to either ICU and were subjected to physician- or protocol-directed weaning, respectively. According to the algorithm, periodical withdrawal trials (WTs) were mandatory. Interventions were recommended (administration of diuretics, fluid, vasopressors, inotropes, or human albumin) to achieve specific goals (sufficient urine output, balanced fluid status, adequate renal perfusion pressure, optimal oxygen delivery, normoalbuminemia). Clearly stated criteria defined when to abort a WT and to resume RRT for one cycle, followed by another WT.

RESULTS

Urine output and S_cvO₂ during WTs were higher with protocol-directed weaning, as well as the amount of administered fluids. WT abort ratio was 48% with a tendency to prolonged WT duration, compared to 64% in the reference patients. No relevant adverse side effects were observed.

CONCLUSION

Our data show the feasibility of a structured approach to wean AKI patients from RRT that bundles established interventions and brings the weaning into the physician's focus.

Formal guidelines: management of acute respiratory distress syndrome

Fifteen recommendations and a therapeutic algorithm regarding the management of acute respiratory distress syndrome (ARDS) at the early phase in adults are proposed. The Grade of Recommendation Assessment, Development and Evaluation (GRADE) methodology has been followed. Four recommendations (low tidal volume, plateau pressure limitation, no oscillatory ventilation, and prone position) had a high level of proof (GRADE 1 + or 1 -); four (high positive end-expiratory pressure [PEEP] in moderate and severe ARDS, muscle relaxants, recruitment maneuvers, and venovenous extracorporeal membrane oxygenation [ECMO]) a low level of proof (GRADE 2 + or 2 -); seven (surveillance, tidal volume for non ARDS mechanically ventilated patients, tidal volume limitation in the presence of low plateau pressure, PEEP > 5 cmH2O, high PEEP in the absence of deleterious effect, pressure mode allowing spontaneous ventilation after the acute phase, and nitric oxide) corresponded to a level of proof that did not allow use of the GRADE classification and were expert opinions. Lastly, for three aspects of ARDS management (driving pressure, early spontaneous ventilation, and extracorporeal carbon dioxide removal), the experts concluded that no sound recommendation was possible given current knowledge. The recommendations and the therapeutic algorithm were approved by the experts with strong agreement.

Formal guidelines: management of acute respiratory distress syndrome

Fifteen recommendations and a therapeutic algorithm regarding the management of acute respiratory distress syndrome (ARDS) at the early phase in adults are proposed. The Grade of Recommendation Assessment, Development and Evaluation (GRADE) methodology has been followed. Four recommendations (low tidal volume, plateau pressure limitation, no oscillatory ventilation, and prone position) had a high level of proof (GRADE 1 + or 1 −); four (high positive end-expiratory pressure [PEEP] in moderate and severe ARDS, muscle relaxants, recruitment maneuvers, and venovenous extracorporeal membrane oxygenation [ECMO]) a low level of proof (GRADE 2 + or 2 −); seven (surveillance, tidal volume for non ARDS mechanically ventilated patients, tidal volume limitation in the presence of low plateau pressure, PEEP > 5 cmH2O, high PEEP in the absence of deleterious effect, pressure mode allowing spontaneous ventilation after the acute phase, and nitric oxide) corresponded to a level of proof that did not allow use of the GRADE classification and were expert opinions. Lastly, for three aspects of ARDS management (driving pressure, early spontaneous ventilation, and extracorporeal carbon dioxide removal), the experts concluded that no sound recommendation was possible given current knowledge. The recommendations and the therapeutic algorithm were approved by the experts with strong agreement.

Comparing Ultrasound-based Diaphragmatic Excursion with Rapid Shallow Breathing Index as a Weaning Predictor

Background

A challenging task in the intensive care unit is weaning intubated patients from mechanical ventilation. The most commonly used weaning parameter, the rapid shallow breathing index (RSBI), gives thorough guidance on extubation timing with spontaneous breathing trials. Diaphragm plays vital role in tidal volume generation. The main objective of the study was to compare ultrasound-based diaphragmatic excursion (DE) with RSBI as weaning predictors.

Methods

We conducted an observational prospective cohort study on patients on mechanical ventilation. During a spontaneous breathing trial (SBT) we simultaneously evaluated right hemidiaphragm excursion by using M-mode ultrasonography as well as the RSBI. To be included, patients must have been on mechanical ventilation for longer than 48 hours, have no excessive tracheobronchial secretions, and their underlying critical illness (for which they were intubated) must be resolved. Patients younger than 14 years, patients with neuromuscular disorder, patients with pneumothorax, and patients with cervical spine injury were excluded from the study. We analyzed the data to determine the significance of DE and RSBI.

Results

A total of 90 patients were included in our study; 54 (60%) were men, and 36 (40%) were women. The average age of all the participants was 55 ± 16 years (range, 19 to 83 years). Sixty-two patients (68.9%) were successfully weaned. The mean DE was 1.44 ± 0.26 cm, and the mean RSBI was 56.88 ± 8.30 in all patients. Successful weaning patients had a mean DE of 1.51 ± 0.26 cm and a mean RSBI of 54.05 ± 7.00. The greater the DE value, the greater the weaning success rate, and the lesser the RSBI value, the greater the weaning success rate. The area under the receiver operator curve for DE and RSBI was 0.795 and 0.815, respectively (p < 0.0001).

Conclusion

RSBI is an optimized clinical predictor in classifying weaning outcomes for intubated patients, but DE is also helpful in extubation assurance and reintubation prevention.

Monitoring of Electrical Activity of the Diaphragm Shows Failure of T-Piece Trial Earlier than Protocol-Based Parameters in Prolonged Weaning in Non-communicative Neurological Patients

BACKGROUND

The weaning target in tracheotomised patients is not extubation, but spontaneous breathing without the support of a ventilator. Overloading the respiratory pump during such spontaneous breathing trials is unfavorable, prolongs weaning time, and increases morbidity and mortality. The goal of this study was to evaluate the electrical activity of the diaphragm during a t-piece trial in non-communicative neurological patients and the comparison to clinical parameters of exhaustion.

METHODS

During multiple t-piece trials, the electrical activity of the diaphragm was obtained before, during and after the end of the trial. T-piece trials were grouped based on the reason for stopping the trial (exhaustion or allotted time period).

RESULTS

Twenty-nine tracheotomised patients in prolonged weaning (29 ± 22 days ventilated at the start of the study) were included in a prospective observational study. T-piece trials (n = 152; 5 ± 2 per patient) were grouped based on the reason for stopping the trial (n = 91 because of exhaustion; n = 61 because of the allotted time period). We found that the electrical activity of the diaphragm exhibits an earlier increase than protocol-based clinical parameters in patients who failed the trial due to exhaustion. The electrical activity of the diaphragm shows no relevant difference during the t-piece trial in patients in whom the trial was stopped due to the allotted time period per protocol.

CONCLUSIONS

Monitoring the electrical activity of the diaphragm in non-communicative neurological patients in prolonged weaning allows earlier detection of exhaustion than protocol-based parameters.

Comparison of Lung Ultrasound-based Weaning Indices with Rapid Shallow Breathing Index: Are They Helpful?

Background and Aims:

The diaphragm is considered the main respiratory muscle and difficulty in weaning can occur because of impaired diaphragmatic function. Hence, monitoring diaphragmatic function is important. The aim of this study is to assess the ability of various lung ultrasound (US) indices and the rapid shallow breathing index (RSBI) to predict the outcome of the weaning process and compare them with RSBI.

Materials and Methods:

This was a prospective study conducted on patients admitted to critical care unit at a tertiary care hospital in north India from February 2017 to June 2017. Patients were put to spontaneous breathing trial (SBT) when they met the weaning criteria. Initial US was done immediately after putting the patient on SBT to check anatomy of the diaphragm and rule out patients according to exclusion criteria. This was followed by complete lung US (LUS) after 20 min of SBT.

Results:

The RSBI performed better than all other parameters, with an area under the curve (AUC) of 0.996. The sensitivity and specificity is 100%. Only comparable to RSBI is the speed of diaphragmic contraction (DC) which has AUC of 0.93. All other parameters had an AUC <0.8. Moreover, the DC and LUS score are strongly positively correlated with RSBI, whereas diaphragmic excursion and diaphragmic thickness fraction (DTF %) are weakly correlated.

Conclusion:

In Intensive Care Unit, RSBI is the best clinical tool for weaning, and DC is found to be the best parameter for weaning among the US-based weaning parameters. It can even be a substitute for RSBI, in today's world of real-time monitoring methods.

Electrical impedance tomography for predicting failure of spontaneous breathing trials in patients with prolonged weaning

Background

Spontaneous breathing trials (SBTs) on a T-piece can be difficult in patients with prolonged weaning because of remaining de-recruitment phenomena and/or insufficient ventilation. There is no clinically established method existent other than experience for estimating whether an SBT is most probably beneficial. Electrical impedance tomography (EIT) is a clinical useful online monitoring technique during mechanical ventilation, particularly because it enables analysis of effects of regional ventilation distribution. The aim of our observational study was to examine if EIT can predict whether patients with prolonged weaning will benefit from a planned SBT.

Methods

Thirty-one patients were examined. Blood gas analysis, vital parameter measurements, and EIT recordings were performed at three time points: (1) baseline with pressure support ventilation (PSV) (t0), (2) during a T-piece trial (t1), and (3) after resumption of PSV (t2). Calculation of EIT parameters was performed, including the impedance ratio (IR), the tidal variation of impedance (TIV), the changes in end-expiratory lung impedance (ΔEELI), the global inhomogeneity index (GI), and the regional ventilation delay (RVD) index with use of different thresholds of the percentage inspiration time (RVD40, RVD60, RVD80). The predictive power of the baseline GI with regard to clinical impairment of an SBT was analyzed by means of ROC curves. Clinical deterioration was assumed when tidal volume was decreased by at least 20 ml after the T-piece trial, measured at t2.

Results

Partial pressure of arterial oxygen significantly decreased at t1 (71 ± 15 mmHg) compared with t0 (85 ± 17 mmHg, p < 0.05) and t2 (82 ± 18 mmHg, p < 0.05). The IR trended toward higher values during t1. At t1, TIV and ΔEELI significantly decreased. The GI was significantly increased at t1 (t0 59.3 ± 46.1 vs t1 81.5 ± 62.5, p = 0.001), as were all RVD indexes. Assuming a GI cutoff value of >40, sensitivity of 85% and specificity of 50% were reached for predicting an increased future tidal volume.

Conclusions

EIT enables monitoring of regional ventilation distribution during SBTs and is suitable to estimate whether an SBT probably will be beneficial for an individual patient. Therefore, the application of EIT can support clinical decisions regarding patients in the phase of prolonged weaning.

How Mechanical Ventilation Measurement, Cutoff and Duration Affect Rapid Shallow Breathing Index Accuracy: A Randomized Trial

BACKGROUND

Decreased accuracy of the rapid shallow breathing index (RSBI) can stem from 1) the method used to obtain this index, 2) duration of mechanical ventilation (MV), and 3) the established cutoff point. The objective was to evaluate the values of RSBI determined by three different methods, using distinct MV times and cutoff points.

METHODS

This prospective study included 40 subjects. Before extubation, three different methods were employed to measure RSBI: pressure support ventilator (PSV) (PSV = 5 - 8 cm H₂O; positive end-expiratory pressure (PEEP) = 5 cm H₂O) (RSBI_MIN), automatic tube compensation (ATC) (PSV = 0, PEEP = 5 cm H₂O, and 100% tube compensation) (RSBI_ATC), and disconnected MV (RSBI_SP). The results were analyzed according to the MV period (less than or over 72 h) and to the outcome of extubation (< 72 h, successful and failed; > 72 h successful and failed). The accuracy of each method was determined at different cutoff points (105, 78, and 50 cycles/min/L).

RESULTS

The RSBI_MIN, RSBI_ATC, and RSBI_SP values in the group < 72 h were 38 ± 18, 45 ± 26 and 55 ± 22; in the group > 72 h, RSBI_SP value was higher than those of RSBI_ATC and RSBI_MIN (78 ± 29, 51 ± 19 and 39 ± 14) (P < 0.001). For patients with MV > 72 h who failed in removing MV, the RSBI_SP was higher (93 ± 28, 58 ± 18 and 41 ± 10) (P < 0.000), with greater accuracy at cutoff of 78.

CONCLUSION

RSBI_SP associated with cutoff point < 78 cycles/min/L seems to be the best strategy to identify failed extubation in subjects with MV for over 72 h.

Controversies in Weaning from Mechanical Ventilation

Invasive mechanical ventilation can successfully support the patient with acute respiratory failure, but it is associated with considerable risks. Numerous complications of invasive mechanical ventilation have been identified, and these may contribute to increased mortality. Therefore after clinical improvement has occurred, considerable emphasis is placed on expeditiously freeing the patient from the ventilator. This process of getting a patient off mechanical ventilation has been variably termed weaning, liberation, or discontinuation (terms which may be used interchangeably), and can be further divided into “readiness testing” and “progressive withdrawal.” Over the last decade, new developments in our understanding of the process of weaning have provided investigators with the tools to address a number of key questions: How should readiness for weaning (and trials of spontaneous breathing) be determined? What is the role of weaning parameters in deciding when to initiate the weaning process? What is the best mode for conducting a spontaneous breathing trial and how should the patient be monitored? What are the mechanisms for weaning (and spontaneous breathing trial) failure? What is the best technique to facilitate progressive withdrawal? What other factors can facilitate liberation from mechanical ventilation? What are the risks of extubation failure and how can extubation outcome best be predicted? What is the role for protocols in facilitating weaning from mechanical ventilation?.

The optimum timing to wean invasive ventilation for patients with AECOPD or COPD with pulmonary infection

COPD is characterized by a progressive decline in lung function and mental and physical comorbidities. It is a significant burden worldwide due to its growing prevalence, comorbidities, and mortality. Complication by bronchial-pulmonary infection causes 50%-90% of acute exacerbations of COPD (AECOPD), which may lead to the aggregation of COPD symptoms and the development of acute respiratory failure. Non-invasive or invasive ventilation (IV) is usually implemented to treat acute respiratory failure. However, ventilatory support (mainly IV) should be discarded as soon as possible to prevent the onset of time-dependent complications. To withdraw IV, an optimum timing has to be selected based on weaning assessment and spontaneous breathing trial or replacement of IV by non-IV at pulmonary infection control window. The former method is more suitable for patients with AECOPD without significant bronchial-pulmonary infection while the latter method is more suitable for patients with AECOPD with acute significant bronchial-pulmonary infection.

Evaluation of a systematic approach to weaning of tracheotomized neurological patients: an early interrupted randomized controlled trial

Background

While a systematic approach to weaning reduces the rate of extubation failure in intubated brain-injured patients, no data are available on the weaning outcome of these patients after tracheotomy. We aimed to assess whether a systematic approach to disconnect tracheotomized neurological and neurosurgical patients off the ventilator (intervention) is superior to the sole physician’s judgment (control). Based on previous work in intubated patients, we hypothesized a reduction of the rate of failure within 48 h from 15 to 5 %. Secondary endpoints were duration of mechanical ventilation, ICU length of stay and mortality.

Methods

We designed a single center randomized controlled study. Since no data are available on tracheotomized patients, we based our a priori power analysis on results derived from intubated patients and calculated an overall sample size of 280 patients.

Results

After inclusion of 168 consecutive patients, the trial was interrupted because the attending physicians judged the observed rate of reconnection to be much greater than expected. The overall rate of failure was 29 %, confirming the physicians’ judgment. Twenty-one patients (24 %) in the intervention group and 27 (33 %) controls were reconnected to the ventilator within 48 h (p = 0.222). The main reasons for failure were respiratory distress (80 and 88 % in the treatment and control group, respectively), hemodynamic impairment (15 and 4 % in the treatment and control group, respectively), neurological deterioration (4 % in the control group only). The duration of mechanical ventilation was of 412 ± 202 h and 402 ± 189 h, in the control and intervention group, respectively. ICU length of stay was on average of 23 days for both groups. ICU mortality was 6 % in the control and 2 % in the intervention group without significant differences.

Conclusion

We found no difference between the two groups under evaluation, with a rate of failure much higher than expected. Consequent to the early interruption, our study results to be underpowered. Based on the results of the present study, a further trial should overall enroll 790 patients.

Trial registration: ACTRN12612000372886

Clinical outcomes associated with high, intermediate, and low rates of failed extubation in an intensive care unit

PURPOSE

Extubation failure is associated with adverse outcomes in mechanically ventilated patients, and it is believed that high rates of failed planned extubation (FPE) should be avoided. However, many believe that very low rates may also correlate with adverse outcomes if resulting from overly conservative weaning practices. We examined the relationship between the percentage of FPE (%FPE) and associated outcomes, with the aim of elucidating a favorable middle range.

METHODS

A total of 1395 extubations were analyzed in mechanically ventilated subjects. Monthly %FPE values were separated into tertiles. Ventilator-free days (VFDs), intensive care unit-free days (IFDs), and mortality were compared among tertiles.

RESULTS

Monthly %FPE tertiles were as follows: low, less than 7%; intermediate, 7% to 15%; and high, greater than 15%. There were significant differences in VFDs and IFDs by tertile from low to high (VFDs: low, 11.8; intermediate, 12.1; high, 9.9 [P = .003]; IFDs: low, 10.5; intermediate, 10.7; high, 9.0 [P = .033]). Post hoc comparisons demonstrated significant differences between the middle and high tertiles for both VFDs and IFDs.

CONCLUSIONS

Although exact rates may vary depending on setting, this suggests that a high %FPE (>15) should be avoided in the intensive care unit and that there may be an intermediate range where ventilator outcomes are optimized.

Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation

INTRODUCTION

The purpose of this study was to evaluate if ultrasound derived measures of diaphragm thickening, rather than diaphragm motion, can be used to predict extubation success or failure.

METHODS

Sixty-three mechanically ventilated patients were prospectively recruited. Diaphragm thickness (tdi) was measured in the zone of apposition of the diaphragm to the rib cage using a 7-10 MHz ultrasound transducer. The percent change in tdi between end-expiration and end-inspiration (Δtdi%) was calculated during either spontaneous breathing (SB) or pressure support (PS) weaning trials. A successful extubation was defined as SB for >48 h following endotracheal tube removal.

RESULTS

Of the 63 subjects studied, 27 patients were weaned with SB and 36 were weaned with PS. The combined sensitivity and specificity of Δtdi%≥30% for extubation success was 88% and 71%, respectively. The positive predictive value and negative predictive value were 91% and 63%, respectively. The area under the receiver operating characteristic curve was 0.79 for Δtdi%.

CONCLUSIONS

Ultrasound measures of diaphragm thickening in the zone of apposition may be useful to predict extubation success or failure during SB or PS trials.

Ventilatory management and extubation criteria of the neurological/neurosurgical patient

Approximately 200 000 patients per year will require mechanical ventilation secondary to neurological injury or disease. The associated mortality, morbidity, and costs are significant. The neurological patient presents a unique set of challenges to airway management, mechanical ventilation, and defining extubation readiness. Neurological injury and disease can directly or indirectly involve the process involved with respiration or airway control. This article will review the basics of airway management and mechanical ventilation in the neurological patient. The current state of the literature evaluating extubation criteria in the neurological patient will also be reviewed.

Respiratory rate as a predictor of weaning failure from mechanical ventilation

BACKGROUND AND OBJECTIVE

There is not an ideal predictor of weaning from mechanical ventilation (MV). In a large meta-analysis, despite methodological limitations, respiratory rate (RR) was considered a promising predictor. The aim of this study was to evaluate RR as a predictor of weaning failure from MV.

METHODS

We prospectively evaluated 166 patients scheduled for weaning from MV. RR and other essential criteria for weaning were evaluated at an early stage of screening. Patients who met the essential screening criteria for weaning underwent spontaneous breathing trial. RR was compared with the following outcomes: weaning success/failure or extubation failure.

RESULTS

Weaning success was present in 76.5% and weaning failure in 17.5% of patients. There were 6% of reintubations. The predictive power for RR weaning failure, RR best cut-off point > 24 breaths per minute (rpm), was: sensitivity 100%, specificity 85%, and accuracy 88% (ROC curve, p < 0.0001). Of the patients with weaning failure, 100% were identified by RR during screening (RR cut-off > 24 rpm). There were 15% false positives, weaning successes with RR > 24 rpm.

CONCLUSION

RR was an effective predictor of weaning failure. The best cut-off point was RR > 24 rpm, which differed from those reported in the literature (35 and 38 rpm). Only 6% of patients were reintubated, but RR or other weaning criteria did not identify them.

Incidence, indication and complications of postoperative reintubation after elective intracranial surgery

CONTEXT AND OBJECTIVE There are no reports on reintubation incidence and its causes and consequences during the postoperative period following elective intracranial surgery. The objective here was to evaluate the incidence of reintubation and its causes and complications in this situation. DESIGN AND SETTING Prospective cohort study, using data obtained at a tertiary university hospital between 2003 and 2006. METHODS 169 patients who underwent elective intracranial surgery were studied. Preoperative assessment was performed and the patients were followed up until hospital discharge or death. The rate of reintubation with its causes and complications was ascertained. RESULTS The incidence of reintubation was 12.4%, and the principal cause was lowered level of consciousness (71.5%). There was greater incidence of reintubation among females (P = 0.028), and greater occurrence of altered level of consciousness at the time of extubation (P < 0.0001). Reintubated patients presented longer duration of mechanical ventilation (P < 0.0001), longer stays in the intensive care unit (ICU) and in the hospital (P < 0.0001), greater incidence of pulmonary complications (P < 0.0001), greater need for reoperation and tracheostomy, and higher mortality (P < 0.0001). CONCLUSION The incidence of reintubation in these patients was 12.4%. The main cause was lowering of the level of consciousness. Female gender and altered level of consciousness at the time of extubation correlated with higher incidence of reintubation. Reintubation was associated with pulmonary complications, longer durations of mechanical ventilation, hospitalization and stay in the ICU, greater incidence of tracheostomy and mortality.

Effect of continuous oral suctioning on the development of ventilator-associated pneumonia: a pilot randomized controlled trial

BACKGROUND

Both continuous and intermittent aspiration of subglottic secretions by means of specially designed endotracheal tubes containing a separate dorsal lumen that opens into the subglottic region have been shown to be useful in reducing ventilator-associated pneumonia (VAP). However, the high cost of these tubes restricts their use.

OBJECTIVE

The aim of this pilot randomized controlled trial was to test the effect of a low-cost device (saliva ejector) for continuous oral suctioning (COS) on the incidence of VAP in patients receiving mechanical ventilation.

METHODS

The study was conducted in the six-bed medical-surgical ICU of a hospital with over 400 beds that provides comprehensive medical services to the public. The design of this study was a parallel-group randomized controlled trial. While both the experimental and control groups used the conventional endotracheal tube, the saliva ejector was only applied to patients assigned to the experimental group. The device was put between the patient's cheek and teeth, and then connected to 100mmHg of suction for the continuous drainage of saliva.

RESULTS

Fourteen patients were randomized to receive COS and 13 patients were randomized to the control group. The two groups were similar in demographics, reasons for intubation, co-morbidity, and risk factors for acquiring VAP. VAP was found in 3 patients (23.1%; 71 episodes of VAP per 1000 ventilation days) receiving COS and in 10 patients (83.3%; 141 episodes of VAP per 1000 ventilation days) in the control group (relative risk, 0.28; 95% confidence interval, 0.10-0.77; p=0.003). The duration of mechanical ventilation in the experimental group was 3.2 days (SD 1.3), while that in the control group was 5.9 days (SD 2.8) (p=0.009); and the length of ICU stay was 4.8 days (SD 1.6) versus 9.8 days (SD 6.3) for the experimental and control groups, respectively (p=0.019).

CONCLUSION

Continuous clearance of oral secretion by the saliva ejector may have an important role to play in reducing the rate of VAP, decreasing the duration of mechanical ventilation, and shortening the length of stay of patients in the ICU.

A clinical description of extubation failure in patients with primary brain injury

BACKGROUND

Patients with acute brain injury but normal lung function are often intubated for airway protection, but extubation often fails. Currently, no clinical data exist that describe the events leading to extubation failure in this population. We examined the extubation failure rate, reintubation rate, and clinical characteristics of patients whose reason for intubation was a primary neurological injury. We then identified the clinical characteristics of those patients with primary brain injury who were reintubated.

METHODS

We conducted a retrospective review of patients admitted to the neurocritical care unit of a tertiary care hospital from January 2002 to March 2007.

RESULTS

Of 1,265 patients who were intubated because of primary neurological injury of brain, spinal cord, or peripheral nerve, 25 (2%) died before extubation and 767 (61%) were successfully extubated. Tracheostomies were placed in 181 (14%) patients, of which, 77 (6.1%) were completed before a trial of extubation and 104 (8.2%) after extubation failure. A total of 129 (10%) patients were reintubated; 77 (6.1%) were reintubated within 72 h, meeting the definition of extubation failure. The other 52 (4.1%) were intubated after 72 h usually in the setting of pneumonia or decreased mental status. Ninety-nine of the patients reintubated had primary brain injury and resulting encephalopathy. All were successfully reintubated. Most patients intubated as a result of a primary brain injury (981) were successfully extubated. The most common clinical scenario leading to reintubation in these encephalopathic patients was respiratory distress associated with altered mental status [59 patients (59%)]. These patients usually had atelectasis and decreased minute ventilation, independent of fever, pneumonia, aspiration, and increased work of breathing [39 patients (39%)].

CONCLUSION

The extubation failure rate in our neurocritical care unit is low. In patients with encephalopathy and primary brain injury who were reintubated, respiratory distress caused by altered mental status was the most common cause of reintubation. These patients demonstrated signs disrupted ventilation usually with periods of prolonged hypoventilation. Increased work of breathing from lung injury due to pneumonia or aspiration was not the most common cause of reintubation in this population.

Clinical Prediction of Weaning and Extubation in Australian and New Zealand Intensive Care Units

Our objective was to describe, in Australian and New Zealand adult intensive care units, the relative frequency in which various clinical criteria were used to predict weaning and extubation, and the weaning methods employed.

Participant intensivists at 55 intensive care units completed a self-administered questionnaire, using visual analogue scales (0=not at all predictive, 10=perfectly predictive, not used=null score) to record the perceived utility of 30 potential predictors.

Survey response rate was 71% (164/230). Those variables thought most predictive of weaning readiness were respiratory rate (median score 8.0, interquartile range 7.0 to 8.6) effective cough (7.3, 5.9 to 8.2) and pressure support setting (7.2, 6.0 to 8.0). The most highly rated predictors of extubation success were effective cough (8.0, 7.0 to 9.0), respiratory rate (8.0, 7.0 to 8.5) and Glasgow Coma Score (7.9, 6.1 to 8.3). Variables perceived least predictive of weaning and extubation success were P0.1, Acute Physiological and Chronic Health Evaluation score II, mean arterial pressure, electrolytes and maximum inspiratory pressure (individual median scores <5). Most popular clinical criteria were those perceived to have high predictive accuracy, both for weaning (respiratory rate 96%, pressure support setting 94% and Glasgow coma score 91%) and extubation readiness (respiratory rate 98%, effective cough 94% and Glasgow Coma Score 92%). Weaning mostly employed pressure support ventilation (55%), with less use of synchronised intermittent mandatory ventilation (32%) and spontaneous breathing trials (13%).

Classic ventilatory performance predictors including respiratory rate and effective cough were reported to be of greater clinical utility than other more recently proposed measures.

Shortening ventilatory support with a protocol based on daily extubation screening and noninvasive ventilation in selected patients

BACKGROUND

Prolonged invasive mechanical ventilation and reintubation are associated with adverse outcomes and increased mortality. Daily screening to identify patients able to breathe without support is recommended to reduce the length of mechanical ventilation. Noninvasive positive-pressure ventilation has been proposed as a technique to shorten the time that patients remain on invasive ventilation.

METHODS

We conducted a before-and-after study to evaluate the efficacy of an intervention that combined daily screening with the use of noninvasive ventilation immediately after extubation in selected patients. The population consisted of patients who had been intubated for at least 2 days.

RESULTS

The baseline characteristics were similar between the groups. The intervention group had a lower length of invasive ventilation (6 [4;9] vs. 7 [4;11.5] days, p = 0.04) and total (invasive plus noninvasive) ventilator support (7 [4;11] vs. 9 [6;8], p = 0.01). Similar reintubation rates within 72 hours were observed for both groups. In addition, a lower ICU mortality was found in the intervention group (10.8% vs. 24.3%, p = 0.03), with a higher cumulative survival probability at 60 days (p = 0.05). Multivariate analysis showed that the intervention was an independent factor associated with survival (RR: 2.77; CI 1.14-6.65; p = 0.03), whereas the opposite was found for reintubation at 72 hours (RR: 0.27; CI 0.11-0.65; p = 0.01).

CONCLUSION

The intervention reduced the length of invasive ventilation and total ventilatory support without increasing the risk of reintubation and was identified as an independent factor associated with survival.

Not-so-trivial pursuit: mechanical ventilation risk reduction

As many as half of critically ill patients require mechanical ventilation. In this article, a program of research focused on reduction of risk associated with mechanical ventilation is reviewed. Airway management practices can have profound effects on outcomes in these patients. How patients are suctioned, types of processes used, effects of suctioning in patients with lung injury, and open versus closed suctioning systems all have been examined to determine best practices. Pneumonia is a common complication of mechanical ventilation (ventilator-associated pneumonia), and use of higher backrest elevations reduces risk of pneumonia, although compliance with such recommendations varies. The studies reviewed here describe backrest elevation practices, factors that affect backrest elevation, and the effect of backrest elevation on ventilator-associated pneumonia. Oral care strategies also have been investigated to determine their effect on ventilator-associated pneumonia. Oral care practices are reported to hold a low care priority, vary widely across care providers, and differ in intubated versus nonintubated patients. However, in several studies, oral applications of chlorhexidine have reduced the occurrence of ventilator-associated pneumonia. Although ventilator patients require sedation, sedation is associated with significant risks. The overall goals of sedation are to provide physiological stability, to maintain ventilator synchrony, and to ensure patients' comfort-although methods to evaluate achievement of these goals are limited. Reducing risks associated with mechanical ventilation in critically ill patients is a complex and interdisciplinary process. Our understanding of the risks associated with mechanical ventilation is constantly changing, but care of these patients must be based on the best evidence.

Economic stress and misaligned incentives in critical care medicine in the United States

OBJECTIVES

This review will provide an overview of issues with economic ramifications intrinsic to the management of intensive care resources and identify some of the external pressures that ultimately influence the provision of intensive care services.

DESIGN

A review of the current literature was performed.

RESULTS

Economic stress is a reality of the management of intensive care resources. The nature of critical care medicine as a technologically heavy, labor intensive, high-cost, limited resource, combined with a projected increase in demand in an era of cost containment, presents an array of challenges.

CONCLUSIONS

It is in the best interest of the care of our patients that critical care providers increase awareness of the many factors influencing our practice economically. It is through such understanding that challenges can be met, solutions can be found, and the quality of intensive care can be improved in a financially sustainable environment.

Use of N-terminal pro-brain natriuretic peptide to detect acute cardiac dysfunction during weaning failure in difficult-to-wean patients with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the utility of serial measurements of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) to detect acute cardiac dysfunction during weaning failure in difficult to wean patients with chronic obstructive pulmonary disease.

DESIGN

Prospective observational cohort study.

SETTING

A 14-bed general intensive care unit in a university hospital.

PATIENTS

Nineteen patients mechanically ventilated for chronic obstructive pulmonary disease exacerbation who were difficult to wean.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cardiac and hemodynamic variables, arterial and central venous blood gas, breathing pattern, respiratory mechanics, indexes of oxygen cost of breathing, and plasma levels of NT-proBNP were measured and analyzed immediately before (baseline) and at the end of a spontaneous breathing trial. Eight of 19 patients (42%) were identified with acute cardiac dysfunction at the end of the weaning trial. Baseline NT-proBNP levels were significantly higher (median 5000, interquartile range 4218 pg/mL) in these patients than in patients without evidence of acute cardiac dysfunction (median 1705, interquartile range 3491 pg/mL). Plasma levels of NT-proBNP increased significantly at the end of the spontaneous breathing trial only in patients with acute cardiac dysfunction (median 12,733, interquartile range 16,456 pg/mL, p < .05). The elevation in NT-proBNP at the end of the weaning trial had a good diagnostic performance in detecting acute cardiac dysfunction, as estimated by area under the receiver operating characteristic curve analysis (area under the curve 0.909, se 0.077, 95% confidence interval 0.69-0.98; p < .0001, cutoff = 184.7 pg/mL).

CONCLUSIONS

Serial measurements of NT-proBNP plasma levels provided a noninvasive manner to detect acute cardiac dysfunction during an unsuccessful weaning trial in difficult to wean patients with chronic obstructive pulmonary disease. The utility of this test as a complement of the standard clinical monitoring of the weaning trial deserves further investigation.

Timing of tracheostomy as a determinant of weaning success in critically ill patients: a retrospective study

Introduction

Tracheostomy is frequently performed in critically ill patients for prolonged intubation. However, the optimal timing of tracheostomy, and its impact on weaning from mechanical ventilation and outcomes in critically ill patients who require mechanical ventilation remain controversial.

Methods

The medical records of patients who underwent tracheostomy in the medical intensive care unit (ICU) of a tertiary medical centre from July 1998 to June 2001 were reviewed. Clinical characteristics, length of stay in the ICU, rates of post-tracheostomy pneumonia, weaning from mechanical ventilation and mortality rates were analyzed.

Results

A total of 163 patients (93 men and 70 women) were included; their mean age was 70 years. Patients were classified into two groups: successful weaning (n = 78) and failure to wean (n = 85). Shorter intubation periods (P = 0.02), length of ICU stay (P = 0.001) and post-tracheostomy ICU stay (P = 0.005) were noted in patients in the successful weaning group. Patients who underwent tracheostomy more than 3 weeks after intubation had higher ICU mortality rates and rates of weaning failure. The length of intubation correlated with the length of ICU stay in the successful weaning group (r = 0.70; P < 0.001). Multivariate analysis revealed that tracheostomy after 3 weeks of intubation, poor oxygenation before tracheostomy (arterial oxygen tension/fractional inspired oxygen ratio <250) and occurrence of nosocomial pneumonia after tracheostomy were independent predictors of weaning failure.

Conclusion

The study suggests that tracheostomy after 21 days of intubation is associated with a higher rate of failure to wean from mechanical ventilation, longer ICU stay and higher ICU mortality.

Management of sedation in mechanically ventilated patients

PURPOSE OF REVIEW

There are many new and exciting studies in the sedation literature. Recent studies of new scoring systems to monitor sedation, new medications, and new insights into post-intensive care unit (ICU) sequelae have brought about interesting ideas for achieving an adequate level of sedation of our patients while minimizing complications.

RECENT FINDINGS

The recent literature focuses on monitoring the level of a patient's sedation with new bedside clinical scoring systems and new technology. Outcomes studies have highlighted problems with both inadequate sedation and excessive sedation in regard to patients' post-ICU psychological health. More insight into drug withdrawal and addiction as complications of ICU care were examined. A new medication for sedation in the ICU has been approved for use, but its role is not yet defined.

SUMMARY

Many patients in the ICU receive mechanical ventilation and will require sedative medications. A frequently overlooked cause of agitation in the ventilated patient is pain, and assessing the adequacy of analgesia is an important part of the continuous assessment of a patient. The goal of sedation is to provide relief while minimizing the development of drug dependency and oversedation. Careful monitoring with bedside scoring systems, the appropriate use of medications, and a strategy of daily interruption can lead to diminished time on the ventilator and in the ICU.

Collaborative Practice: Development, Implementation, and Evaluation of a Weaning Protocol for Patients Receiving Mechanical Ventilation

• Background Use of protocols to reduce weaning time for patients receiving mechanical ventilation helps reduce cost and length of stay. However, implementation of this type of protocol is not easy and requires a consistent collaborative effort.

• Objective To provide a systematic approach to the weaning process by developing, implementing, and evaluating a protocol for weaning patients from mechanical ventilation in a medical respiratory intensive care unit.

• Methods The weaning protocol used was a modification of a protocol developed by Ely et al. Modifications included a more aggressive approach in proceeding to the spontaneous breathing trial, inclusion of the Richmond Agitation-Sedation Scale, and documentation of the production of secretions.

• Results Implementation of the protocol significantly reduced the duration of mechanical ventilation as measured by 8-hour shifts and ventilator days. Although length of stay in the intensive care unit was not significantly reduced (P = .29), a continuing downward trend occurred, from a mean of 8.6 days before the protocol was implemented to 7.9 days during the last 6 months of data collection (P = .07).

• Conclusions The need to provide efficient care requires the collaboration of all disciplines involved in providing patients’ care. The weaning protocol introduced in this study demonstrates the benefits of using a collaborative team to identify best practices and implement them in a practice setting.

The pulmonary physician in critical care. 10: difficult weaning

The study of patients being weaned from mechanical ventilation has offered new insights into the physiology of respiratory failure. Assessment of the balance between respiratory muscle strength, work and central drive is essential if difficulty in weaning occurs, and optimisation of these elements may improve the success of weaning. Psychological support of patients and the creation of units specialising in weaning have also resulted in a higher success rate.

[Factors associated with hospital mortality in patients admitted to the intensive care unit in Colombia]

OBJECTIVES

To describe the demographic features, reasons for hospital admission and factors associated with hospital mortality in patients admitted to intensive care in Colombia.

METHOD

A cohort study of patients admitted to intensive care units (ICUs). Of 89 ICUs identified in Colombia, 20 in ten cities were invited to gather information on 200 consecutive patients admitted to each ICU.

RESULTS

Three thousand sixty-six patient cases were available for analysis. The mean age was 53 years and 43% were women (men vs. women, p < 0.001). The most frequent cause of admission was medical (63.9%), acute myocardial infarction patients (7.1%) comprising the largest group. Severity of disease measured as APACHE II and III was a mean 14.0 (SD 6.9) and 48.3 (SD 23.5), respectively. Multivariate analysis, independent of adjustment for severity (APACHE II or III), showed that the factors associated with hospital death were the need for mechanical ventilation, pupillary response, transfer from a medical ward, and management by the ICU team prior to admission (p < 0.01).

CONCLUSION

The most common reason for admission to an ICU in Colombia was myocardial infarction. Besides severity of disease, other variables related to medical care in Colombia are associated with hospital mortality, such as invasive ventilation. Although these variables may be artifacts related to disease severity, they are more likely to be related to quality of care.

Treatment and prevention of diaphragm fatigue using low-dose dopamine

There is increasing evidence that diaphragm fatigue is a major cause of failure in weaning patients from mechanical ventilation. Patients in intensive care units are often administered dopamine to improve renal blood flow without regard to its effect on diaphragm blood flow. The aim of this study was to investigate if intravenous low-dose dopamine, equivalent to the dose used in intensive care units, can treat and prevent diaphragm fatigue. Diaphragm fatigue was produced in anesthetized rats by inspiratory resistance loading (IRL). The effect on diaphragm shortening, diaphragm blood flow, and aortic blood flow was determined. When diaphragm fatigue was attained, group I was given saline for 30 min while maintaining IRL. At the time of diaphragm fatigue, group II was given low-dose dopamine (2 microg/kg/min) for 30 min while maintaining IRL. In group III, dopamine administration was started before and continued throughout the period of IRL. Administering dopamine after the development of diaphragm fatigue (group II) increased diaphragm performance as measured by increased diaphragm shortening and was accompanied by an increased diaphragm blood flow. Administering dopamine prior to and throughout IRL (group III) prevented diaphragm fatigue. Low-dose dopamine can prevent and/or reverse diaphragm fatigue in rats without a significant change in aortic blood flow. This effect of dopamine may be due to increased oxygen delivery associated with the increased diaphragm blood flow, resulting in less free radical formation and thus less muscle damage.