Independent effects of etiology of failure and time to reintubation on outcome for patients failing extubation

A pilot study of a new test to predict extubation failure

Introduction

To determine whether subjecting patients to 100 ml of additional dead space after a 120-minute weaning trial could predict readiness for extubation.

Methods

This was a prospective, non-randomised pilot study in an intensive care unit at a university hospital with 14 beds. It included all non-tracheostomised patients with improvement of the underlying cause of acute respiratory failure, and those with no need for vasoactive or sedative drugs were eligible. Patients fulfilling the Consensus Conference on Weaning extubation criteria after 120 minutes spontaneous breathing (n = 152) were included. To the endotracheal tube, 100 cc dead space was added for 30 minutes. Patients tolerating the test were extubated; those not tolerating it received six hours of supplementary ventilation before extubation. The measurements taken and main results were: arterial pressure, heart rate, respiratory rate, oxygen saturation, end-tidal carbon dioxide and signs of respiratory insufficiency were recorded every five minutes; and arterial blood gases were measured at the beginning and end of the test. Extubation failure was defined as the need for mechanical and non-invasive ventilation within 48 hours of extubation.

Results

Twenty-two patients (14.5%) experienced extubation failure. Only intercostal retraction was independently associated with extubation failure. The sensitivity (40.9%) and specificity (97.7%) yield a probability of extubation failure of 75.1% for patients not tolerating the test versus 9.3% for those tolerating it.

Conclusions

Observing intercostal retraction after adding dead space may help detect susceptibility to extubation failure. The ideal amount of dead space remains to be determined.

Trial registration

Current Controlled Trials ISRCTN76206152.

Effects of steroids on reintubation and post-extubation stridor in adults: meta-analysis of randomised controlled trials

Introduction

The efficacy of steroid administration before planned tracheal extubation in critical care patients remains controversial with respect to the selection of patients most likely to benefit from this treatment.

Methods

We performed an extensive literature search for adult trials testing steroids versus placebo to prevent reintubation or laryngeal dyspnoea. Studies were evaluated on a five-point scale based on randomisation, double-blinding and follow-up. Our analysis included trials having a score three or higher with patients mechanically ventilated for at least 24 hours and treated with steroids before extubation, taking into account the time of their administration (early vs late) and if the population selected was at risk or not.

Results

Seven prospective, randomised, double-blinded trials, including 1846 patients, (949 of which received steroids) were selected. Overall, steroids significantly decreased the risk of reintubation (relative risk (RR) = 0.58, 95% confidence interval (CI) = 0.41 to 0.81; number-needed-to-treat (NNT) = 28, 95% CI = 20 to 61) and stridor (RR = 0.48, 95% CI = 0.26 to 0.87; NNT = 11, 95% CI = 8 to 42). The effect of steroids on reintubation and stridor was more pronounced for selected high-risk patients, as determined by a reduced cuff leak volume (RR = 0.38, 95% CI = 0.21 to 0.72; NNT = 9, 95% CI = 7 to 19; and RR = 0.40, 95% CI = 0.25 to 0.63; NNT = 5, 95% CI = 4 to 8, respectively). In contrast, steroid benefit was unclear when trials did not select patients for their risk of reintubation (RR = 0.67, 95% CI = 0.45 to 1.00; NNT = 44, 95% CI ≥ 26 to infinity) or stridor (RR = 0.56, 95% CI = 0.20 to 1.55).

Conclusions

The efficacy of steroids to prevent stridor and reintubation was only observed in a high-risk population, as identified by the cuff-leak test and when it was administered at least four hours before extubation. The benefit of steroids remains unclear when patients at high risk are not selected.

Evaluation of a computerized system for mechanical ventilation of infants

OBJECTIVE

To evaluate a computerized system for mechanical ventilation of infants.

METHODS

FLEX is a computerized system that includes the features of a patented mode known as adaptive-support ventilation (ASV). In addition, it has many other features including adjustment of positive end-expiratory pressure (PEEP), fraction of inspired oxygen (F(IO2)), minute ventilation, and control of weaning. It is used as an open-loop decision support system or as a closed-loop technique. Blood gas and ventilation data were collected from 12 infants in the neonatal intensive care at baseline and at the next round of evaluation. This data were input to open-loop version of FLEX. The system recommendations were compared to clinical determinations.

RESULTS

FLEX recommended values for ventilation were on the average within 25% and 16.5% of the measured values at baseline and at the next round of evaluation, respectively. For F(IO2) and PEEP, FLEX recommended values were in general agreement with the clinical settings. FLEX recommendations for weaning were the same as the clinical determinations 50% of the time at baseline and 55% of the time at the next round of evaluation. FLEX did not recommend weaning for infants with weak spontaneous breathing effort or those who showed signs of dyspnea.

CONCLUSIONS

A computerized system for mechanical ventilation is evaluated for treatment of infants. The results of the study show that the system has good potential for use in neonatal ventilatory care. Further refinements can be made in the system for very low-birth-weight infants.

Survey of factors effective on re-intubation among children admitted to pediatric intensive care unit

This study was aimed to recognize the risk factors of re intubation among children who were admitted to pediatric intensive care unit. in an analytical cross-sectional study, the risk factors of reintubation in two groups of patients compared, both groups consist of 55 children, one with successful extubation and another with extubation failure. The study showed that neuromuscular disorders are the main underlying disease in extubation-failure group (p = 0.004). Besides, in comparison between two group of patients who had successful versus failed extubation, hypercapnia (PaCO2 > 50 mmHg) was shown to be the most common cause of both the first intubation (p = 0.003) and reintubation (p = 0.002) in patients who failed extubation. This study shows that neuromuscular disorders as a background, are the most common causes which defeat weaning from ventilator or result in reintubation by induction of hypercapnia.

Survey of factors effective on outcome of weaning from mechanical ventilation

This study was aimed to recognize factors effective on weaning from mechanical ventilation and determine the reasons of unsuccessful Spontaneous Breathing Trial (SBT) and reintubation. The study population consisted of 202 critically ill pediatric patients who received mechanical. When the patient was enrolled in the study, mechanical ventilation support was stopped and the patient underwent a 2 h trial of Spontaneous Breathing Trial (SBT), at the end of the trial if PaCO2 was in normal range was extubated. Of the 202 patients who underwear SBT, 141 attempts had successful trial. The remaining 61 patients had sign of poor tolerance during the trial of spontaneous breathing and were reconnected to the ventilator. One hundred and forty one patients (69.8%) successfully passed the trial. 17 (12%) of above mentioned group required reintubation within 48-72 h. The overall success and failure rate was 61.3 and 38.7%, respectively. Mortality rate in patients who did not tolerate SBT or were extubated, or required reintubation were 13% (8 patients), 11.3% (14 patients) and 23.5% (4 patients), respectively. The most common reasons for reintubation were neuromuscular disease (58.8%) congenital cardiac disease (23.5%) and aspirative pneumonia (17.6%). The finding indicates that two third of intubated patients, respond successfully to SBT and could be extubated and the neuromuscular diseases is the main cause of reintubation.

Swallowing Disorders as a Predictor of Unsuccessful Extubation: A Clinical Evaluation

Background Unsuccessful extubation may be due to swallowing dysfunction that causes airway obstruction and impairs patients’ ability to cough and expectorate.

Objective To determine whether swallowing assessment before extubation is helpful in predicting unsuccessful extubation due to airway secretions.

Methods This prospective study included all patients intubated orotracheally for more than 6 days. Before extubation, 3 tests designed to assess (1) cervical, oral, labial, and lingual motility; (2) gag reflex; and (3) swallowing were used at the bedside. Causes of reintubation were identified, and their relationship to patients’ swallowing function before extubation was evaluated.

Results Sixty-two patients were enrolled. Data on 55 patients reintubated for swallowing dysfunction were analyzed. Nine patients were reintubated because of obstruction related to upper airway secretions. Evaluation before extubation enabled prediction of 7 of those 9 unsuccessful extubations. Among the 23 patients with central nervous system disease, 3 of 4 unsuccessful extubations were predicted. According to a multivariate logistic regression model, motility and swallowing were independent predictors of unsuccessful extubation (area under receiver-operating-characteristic curve, 80%). The gag reflex was the only significant predictor of the ability to cough (area under curve, 73%) and excessive pulmonary secretion (area under curve, 67%). Swallowing was an independent predictor of the need for suctioning (area under curve, 78%).

Conclusions Using simple bedside tests to evaluate swallowing before extubation is helpful when deciding whether to extubate patients who have been intubated for more than 6 days. Involvement of nurses in these decisions would improve patients’ management.

[Field 5. Safety practices procedures for mechanical ventilation. French-speaking Society of Intensive Care. French Society of Anesthesia and Resuscitation]

Invasive or endotracheal mechanical ventilation can lead to numerous complications likely to burden morbidity and mortality of patients in the intensive care unit. Various safety practices for mechanical ventilation may involve intubation, the mechanical ventilation period, weaning and extubation, the use of tracheostomy as well as non-invasive ventilation. The main objective of safety practices described in this chapter is to prevent or avoid the main risks due to invasive mechanical ventilation.

The prediction of extubation success of postoperative neurosurgical patients using frequency-tidal volume ratios

BACKGROUND

The process of discontinuing neurological patients from mechanical ventilation is still controversial. The aim of this study was to report the outcome from extubating patients undergoing elective craniotomy and correlate the result with the measured f/V (t) ratio.

MATERIALS AND METHODS

In a cohort prospective study, all consecutive patients who required mechanical ventilation for up to 6 h after elective craniotomy were eligible for inclusion in this study. Patients passing daily screening criteria automatically received a spontaneous breathing trial (SBT). Immediately previous to the extubation, the expired minute volume (VE), breathing frequency (f), and tidal volume (V (t)) were measured and the breathing frequency-to-tidal volume ratio (f/V (t)) was calculated; consciousness level based on Glasgow Coma Scale (GCS) was evaluated at the same time. The extubation was considered a failure when patients needed reintubation within 48 h.

RESULTS

Ninety-two patients were extubated and failure occurred in 16%. Despite 15 patients failed extubation just one of them presented the f/V (t) score over 105. The best cutoff value for f/V (t) observed was 62, but with low specificity (0.53) and negative predictive values (0.29). Area under the ROC curve for the f/V (t) was 0.69 +/- 0.07 (P = 0.02). Patients who failed the extubation process presented higher incidence of pneumonia (80%), higher need for tracheostomy (33%) and mortality rate of 40%.

CONCLUSION

The f/V (t) ratio does not predict extubation failure in patients who have undergone elective craniotomy. Patients who fail extubation present higher incidence of pneumonia, tracheostomy and higher mortality rate.

Prophylactic administration of parenteral steroids for preventing airway complications after extubation in adults: meta-analysis of randomised placebo controlled trials

OBJECTIVE

To determine whether steroids are effective in preventing laryngeal oedema after extubation and reducing the need for subsequent reintubation in critically ill adults.

DESIGN

Meta-analysis.

DATA SOURCES

PubMed, Cochrane Controlled Trials Register, Web of Science, and Embase with no limitation on language, study year, or publication status. Selection criteria Randomised placebo controlled trials in which parenteral steroids were compared with placebo for preventing complications after extubation in adults. Review methods Search, application of inclusion and exclusion criteria, data extraction, and assessment of methodological quality, independently performed in duplicate. Odds ratios with 95% confidence intervals, risk difference, and number needed to treat were calculated and pooled.

PRIMARY OUTCOME

laryngeal oedema after extubation. Secondary outcome: subsequent reintubation because of laryngeal oedema.

RESULTS

Six trials (n=1923) were identified. Compared with placebo, steroids given before planned extubation decreased the odds ratio for laryngeal oedema (0.38, 95% confidence interval 0.17 to 0.85) and subsequent reintubation (0.29, 0.15 to 0.58), corresponding with a risk difference of -0.10 (-0.12 to -0.07; number needed to treat 10) and -0.02 (-0.04 to -0.01; 50), respectively. Subgroup analyses indicated that a multidose regimen of steroids had marked positive effects on the occurrence of laryngeal oedema (0.14; 0.08 to 0.23) and on the rate of subsequent reintubation (0.19; 0.07 to 0.50), with a risk difference of -0.19 (-0.24 to -0.15; 5) and -0.04 (-0.07 to -0.02; 25). In single doses there was only a trend towards benefit, with the confidence interval including 1. Side effects related to steroids were not found.

CONCLUSION

Prophylactic administration of steroids in multidose regimens before planned extubation reduces the incidence of laryngeal oedema after extubation and the consequent reintubation rate in adults, with few adverse events.

Intelligent decision support systems for mechanical ventilation

OBJECTIVE

An overview of different methodologies used in various intelligent decision support systems (IDSSs) for mechanical ventilation is provided. The applications of the techniques are compared in view of today's intensive care unit (ICU) requirements.

METHODS

Information available in the literature is utilized to provide a methodological review of different systems.

RESULTS

Comparisons are made of different systems developed for specific ventilation modes as well as those intended for use in wider applications. The inputs and the optimized parameters of different systems are discussed and rule-based systems are compared to model-based techniques. The knowledge-based systems used for closed-loop control of weaning from mechanical ventilation are also described. Finally, in view of increasing trend towards automation of mechanical ventilation, the potential utility of intelligent advisory systems for this purpose is discussed.

CONCLUSIONS

IDSSs for mechanical ventilation can be quite helpful to clinicians in today's ICU settings. To be useful, such systems should be designed to be effective, safe, and easy to use at patient's bedside. In particular, these systems must be capable of noise removal, artifact detection and effective validation of data. Systems that can also be adapted for closed-loop control/weaning of patients at the discretion of the clinician, may have a higher potential for use in the future.

Weaning Strategies in Problem Patients

Weaning usually accounts for approximately 40–50% of the total duration of mechanical ventilation. Approximately two-thirds of patients can tolerate withdrawal of ventilation without the need for more gradual weaning, but there are a significant number of patients for whom weaning is difficult. Weaning failure is defined as the failure of a spontaneous breathing trial, or the need for re-intubation within 48 hours of extubation. This article reviews the causes of failure to wean, and outlines a practical approach to dealing with the difficult-to-wean patient. The key to successful weaning combines an approach which optimises ventilation at night, adopts a stepwise approach to reducing ventilatory dependence during the day, and uses non-invasive ventilation as a ‘bridge’ out of the ICU. Having a weaning protocol and ensuring it is initiated in a timely manner is likely to be as important as what is in the protocol.

Corticosteroids for prevention of postextubation laryngeal edema in adults

OBJECTIVE

To evaluate the efficacy and safety of prophylactic corticosteroid therapy in preventing postextubation laryngeal edema (PELE) and the need for reintubation in adults.

DATA SOURCES

Literature was accessed through MEDLINE (1966-January 2008) and the Cochrane Library using the terms laryngeal edema, airway obstruction, postextubation stridor, intubation, glucocorticoids, and corticosteroids. Bibliographies of cited references were reviewed and a manual search of abstracts from recent pulmonary and critical care meetings was completed.

STUDY SELECTION AND DATA EXTRACTION

All English-language, placebo-controlled, randomized studies evaluating the use of prophylactic corticosteroids for the prevention of postextubation laryngeal edema or postextubation stridor (PES) in adults were reviewed.

DATA SYNTHESIS

Although laryngoscopy is the gold standard method for diagnosing PELE, PES is more commonly used for diagnosis in clinical practice. While 3 older studies failed to demonstrate benefit with the prophylactic administration of corticosteroid therapy in terms of reducing PELE, PES, or the need for reintubation, each of these studies evaluated only a single dose of steroid therapy that was initiated only 30-60 minutes prior to a planned extubation in a population of patients at low-risk for PELE. In comparison, 3 newer studies, each using 4 doses of corticosteroid therapy initiated 12-24 hours prior to a planned extubation in patients deemed to be at high baseline risk for developing PELE, demonstrated a reduction in PELE, PES, and the need for reintubation; no safety concerns were identified. Current evidence therefore suggests that prophylactic intravenous methylprednisolone therapy (20-40 mg every 4-6 h) should be considered 12-24 hours prior to a planned extubation in patients at high-risk for PELE (eg, mechanical ventilation > 6 days).

CONCLUSIONS

Data from the most recent well-designed clinical trials suggest that prophylactic corticosteroid therapy can reduce the incidence of PELE and the subsequent need for reintubation in mechanically ventilated patients at high-risk for PELE. Based on this information, clinicians should consider initiating prophylactic corticosteroid therapy in this population. Further studies are needed to establish the optimal dosing regimens as well as the subgroups of patients at high risk for PELE who will derive the greatest benefit from this preventive steroid therapy.

Respiratory care

PURPOSE OF THE REVIEW

Neurosurgical patients frequently develop respiratory complications, adversely affecting neurologic outcome and survival. The review summarizes current literature and management of respiratory complications associated with brain injury.

MAJOR FINDINGS

Respiratory complications are commonly associated with traumatic brain injury and subarachnoid haemorrhage. Lung-protective ventilation with reduced tidal volumes improves outcome in acute lung injury, and should be applied to neurosurgical patients in the absence of increased intracranial pressure. Weaning from the mechanical ventilation should be initiated as soon as possible, although the role of neurological status in the weaning process is not clear. Prevention of pneumonia and aspiration improves survival. In patients with difficult weaning, early bedside percutaneous tracheostomy should be considered.

FURTHER INVESTIGATIONS

Further studies are warranted to elucidate an optimal oxygenation and ventilation in brain-injured patients, weaning strategies, predictors of the failed weaning and extubation, respiratory support in patients with difficulties to wean, and early tracheostomy.

Extubation failure in intensive care unit: Predictors and management

Extubation failure-need for reintubation within 72 h of extubation, is common in intensive care unit (ICU). It can cause increased morbidity, higher costs, higher ICU and hospital length of stay (LOS) and mortality. Patients with advanced age, high severity of illness at ICU admission and extubation, preexisting chronic respiratory and cardiovascular disorders are at increased risk of extubation failure. Unresolved illness, development and progression of organ failure during the time from extubation to reintubation and reintubation itself have been proposed as reasons for increased morbidity and mortality. Parameters used to predict extubation failure can be categorized into parameters assessing respiratory mechanics, airway patency and protection and cardiovascular reserve. Adequate cough strength, minimal secretions and alertness are necessary for successful extubation. Evidence suggests that early institution of non-invasive ventilation and prophylactic administration of methylprednisolone may prevent reintubation in some patients. The intensivist needs to identify patients at high risk of extubation failure and be prepared to reinstitute ventilation early to prevent adverse outcomes.

Therapist driven protocols: a look back and moving into the future

Therapist-driven protocols have been shown to decrease the duration of mechanical ventilation, reduce cost, length of stay, and improve the rate of weaning when compared with physician-directed weaning. This article describes protocols used at the author's institution. It describes how the respiratory therapy service interacts with other services within the hospital to provide the optimal outcome for the patient.

The Early Phase of the Minute Ventilation Recovery Curve Predicts Extubation Failure Better Than the Minute Ventilation Recovery Time

STUDY OBJECTIVES

To determine, in patients who had successful outcomes in spontaneous breathing trials (SBTs), whether the analysis of the minute ventilation (Ve) recovery time obtained by minute-by-minute sequential monitoring after placing the patient back on mechanical ventilation (MV) may be useful in predicting extubation outcome.

DESIGN

Twelve-month prospective observational study.

SETTING

Medical-surgical ICU of a university hospital.

PATIENTS

Ninety-three patients receiving > 48 h of MV.

INTERVENTIONS

Baseline respiratory parameters (ie, respiratory rate, tidal volume, and Ve) were measured under pressure support ventilation prior to the SBT. After tolerating the SBT, patients again received MV with their pre-SBT ventilator settings, and respiratory parameters were recorded minute by minute.

MEASUREMENTS AND RESULTS

Seventy-four patients (80%) were successfully extubated, and 19 patients (20%) were reintubated. Reintubated patients were similar to non-reintubated patients in baseline respiratory parameters and baseline variables, except for age and COPD diagnosis. The recovery time needed to reduce Ve to half the difference between the Ve measured at the end of a successful SBT and basal Ve (RT50%DeltaVe) was lower in patients who had undergone successful extubation than in those who had failed extubation (mean [+/- SD] time, 2.7 +/- 1.2 vs 10.8 +/- 8.4 min, respectively; p < 0.001). Multiple logistic regression adjusted for age, sex, comorbid status, diagnosis (ie, neurocritical vs other), and severity of illness revealed that neurocritical disease (odds ratio [OR], 7.6; p < 0.02) and RT50%DeltaVe (OR, 1.7; p < 0.01) were independent predictors of extubation outcome. The area under the receiver operating characteristic curve for the predictive model was 0.89 (95% confidence interval, 0.81 to 0.96).

CONCLUSION

Determination of the RT50%DeltaVe at the bedside may be a useful adjunct in the decision to extubate, with better results found in nonneurocritical patients.

Weaning from Mechanical Ventilation

Approximately 20% of all mechanically ventilated patients fail their first attempt to wean. Prolonged mechanical ventilation increases morbidity, mortality, and costs. No single weaning parameter predicts patient ability to wean. Weaning studies suggest that daily trials of spontaneous breathing for appropriate patients assured by standing protocol and driven by respiratory care practitioners and/or nurses improve the weaning process and patient outcome.

Special Cases: Mechanical Ventilation of Neurosurgical Patients

Mechanical ventilation has evolved greatly over the last half century, guided primarily by improved comprehension of the relevant pathology/physiology. Neurosurgical patients are a unique subgroup of patients who heavily use this technology for both support, and less commonly, as a therapy. Such patients demand special consideration with regard to mode of ventilation, use of positive end-expiratory pressure, and monitoring. In addition, meeting the ventilatory needs of neurosurgical patients while minimizing ventilatory-induced lung damage can be a challenging aspect of care.

12-h pretreatment with methylprednisolone versus placebo for prevention of postextubation laryngeal oedema: a randomised double-blind trial

BACKGROUND

The efficacy of corticosteroids in reducing the incidence of postextubation laryngeal oedema is controversial. We aimed to test our hypothesis that methylprednisolone started 12 h before a planned extubation could prevent postextubation laryngeal oedema.

METHODS

We did a placebo-controlled, double-blind multicentre trial in 761 adults in intensive-care units. Patients who were ventilated for more than 36 h and underwent a planned extubation received intravenous 20 mg methylprednisolone (n=380) or placebo (381) 12 h before extubation and every 4 h until tube removal. The primary endpoint was occurrence of laryngeal oedema within 24 h of extubation. Laryngeal oedema was clinically diagnosed and deemed serious if tracheal reintubation was needed. Analyses were done on a per protocol and intention-to-treat basis. This trial is registered at ClinicalTrials.gov, number NCT00199576.

FINDINGS

63 patients could not be assessed, mainly because of self-extubation (n=16) or cancelled extubation (44) between randomisation and planned extubation. 698 patients were analysed (343 in placebo group, 355 in methylprednisolone group). Methylprednisolone significantly reduced the incidence of postextubation laryngeal oedema (11 of 355, 3%vs 76 of 343, 22%, p<0.0001), the global incidence of reintubations (13 of 355, 4%vs 26 of 343, 8%, p=0.02), and the proportion of reintubations secondary to laryngeal oedema (one of 13, 8 %vs 14 of 26, 54%, p=0.005). One patient in each group died after extubation, and atelectasia occurred in one patient given methylprednisolone.

INTERPRETATION

Methylprednisolone started 12 h before a planned extubation substantially reduced the incidence of postextubation laryngeal oedema and reintubation. Such pretreatment should be considered in adult patients before a planned extubation that follows a tracheal intubation of more than 36 h.

Risk Factors for Extubation Failure in Patients Following a Successful Spontaneous Breathing Trial

BACKGROUND

To assess the factors associated with reintubation in patients who had successfully passed a spontaneous breathing trial.

METHODS

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.

RESULTS

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 [reference value]).

CONCLUSIONS

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.

Intraoperative and postoperative risk factors for prolonged mechanical ventilation after pediatric cardiac surgery

BACKGROUND

Early extubation after cardiac surgery in children is feasible; however, predictors of prolonged mechanical ventilation (MV) should be recognized as soon as possible.

METHODS

At a tertiary pediatric cardiac center, prospective case series analyses were carried out with a total of 411 patients within 1 year of cardiac surgery. Perioperative factors were evaluated for strength of association with duration of MV > 61 h (medium, MMV) and > 7 days (long, LMV). Two multiple regression models were performed for both cut-off points: one model considered factors identified until 24 h postoperation, the other was performed with all parameters.

RESULTS

One hundred and three patients (25%) were still intubated after 61 h; 38 patients required LMV and they occupied 33% of total intensive care unit (ICU) bed days. If factors occurring until 24 h after surgery were analyzed, duration of cardiopulmonary bypass (CPB), intraoperative transfusion, post-CPB arterial oxygen tension (PaO2/FiO2), and fluid intake on the first day were found to be associated with MMV. Urea nitrogen value, nitric oxide treatment, delayed sternal closure, and tracheobronchomalacia, measured at the same point of time, were independent predictors of LMV. Of all the studied clinical predictors, MMV was associated with pulmonary hypertensive events, delayed sternal closure, peritoneal dialysis, nonvascular pulmonary problems, low output syndrome and fluid intake, while urea nitrogen (24 h), postsurgical neurological events, nitric oxide, tracheobronchomalacia, pulmonary hypertensive events and cardiac reoperations were identified as determinants of LMV.

CONCLUSIONS

Causes of MV after surgery are heterogeneous, vary with time, and have variable impact on the duration of MV.

A multicenter randomized trial of computer-driven protocolized weaning from mechanical ventilation

RATIONALE AND OBJECTIVES

Duration of weaning from mechanical ventilation may be reduced by the use of a systematic approach. We assessed whether a closed-loop knowledge-based algorithm introduced in a ventilator to act as a computer-driven weaning protocol can improve patient outcomes as compared with usual care.

METHODS AND MEASUREMENTS

We conducted a multicenter randomized controlled study with concealed allocation to compare usual care for weaning with computer-driven weaning. The computerized protocol included an automatic gradual reduction in pressure support, automatic performance of spontaneous breathing trials (SBT), and generation of an incentive message when an SBT was successfully passed. One hundred forty-four patients were enrolled before weaning initiation. They were randomly allocated to computer-driven weaning or to physician-controlled weaning according to local guidelines. Weaning duration until successful extubation and total duration of ventilation were the primary endpoints.

MAIN RESULTS

Weaning duration was reduced in the computer-driven group from a median of 5 to 3 d (p=0.01) and total duration of mechanical ventilation from 12 to 7.5 d (p=0.003). Reintubation rate did not differ (23 vs. 16%, p=0.40). Computer-driven weaning also decreased median intensive care unit (ICU) stay duration from 15.5 to 12 d (p=0.02) and caused no adverse events. The amount of sedation did not differ between groups. In the usual care group, compliance to recommended modes and to SBT was estimated, respectively, at 96 and 51%.

CONCLUSIONS

The specific computer-driven system used in this study can reduce mechanical ventilation duration and ICU length of stay, as compared with a physician-controlled weaning process.

The distinct clinical profile of chronically critically ill patients: a cohort study

Introduction

Our goal was to describe the epidemiology, clinical profiles, outcomes, and factors that might predict progression of critically ill patients to chronically critically ill (CCI) patients, a still poorly characterized subgroup.

Methods

We prospectively studied all patients admitted to a university-affiliated hospital intensive care unit (ICU) between 1 July 2002 and 30 June 2005. On admission, we recorded epidemiological data, the presence of organ failure (multiorgan dysfunction syndrome (MODS)), underlying diseases (McCabe score), acute respiratory distress syndrome (ARDS) and shock. Daily, we recorded MODS, ARDS, shock, mechanical ventilation use, lengths of ICU and hospital stay (LOS), and outcome. CCI patients were defined as those having a tracheotomy placed for continued ventilation. Clinical complications and time to tracheal decannulation were registered. Predictors of progression to CCI were identified by logistic regression.

Results

Ninety-five patients (12%) fulfilled the CCI definition and, compared with the remaining 690 patients, these CCI patients were sicker (APACHE II, 21 ± 7 versus 18 ± 9 for non-CCI patients, p = 0.005); had more organ dysfunctions (SOFA 7 ± 3 versus 6 ± 4, p < 0.003); received more interventions (TISS 32 ± 10 versus 26 ± 8, p < 0.0001); and had less underlying diseases and had undergone emergency surgery more frequently (43 versus 24%, p = 0.001). ARDS and shock were present in 84% and 83% of CCI patients, respectively, versus 44% and 48% in the other patients (p < 0.0001 for both). CCI patients had higher expected mortality (38% versus 32%, p = 0.003), but observed mortality was similar (32% versus 35%, p = 0.59). Independent predictors of progression to CCI were ARDS on admission, APACHE II and McCabe scores (odds ratio (OR) 2.26, p < 0.001; OR 1.03, p < 0.01; and OR 0.34, p < 0.0001, respectively). Lengths of mechanical ventilation, ICU and hospital stay were 33 (24 to 50), 39 (29 to 55) and 55 (37 to 84) days, respectively. Tracheal decannulation was achieved at 40 ± 19 days.

Conclusion

CCI patients were a severely ill population, in which ARDS, shock, and MODS were frequent on admission, and who suffered recurrent complications during their stay. However, their prognosis was equivalent to that of the other ICU patients. ARDS, APACHE II and McCabe scores were independent predictors of evolution to chronicity.

Intravenous injection of methylprednisolone reduces the incidence of postextubation stridor in intensive care unit patients*

OBJECTIVE

To determine whether treatment with corticosteroids decreases the incidence of postextubation airway obstruction in an adult intensive care unit.

DESIGN

Clinical experiment.

SETTING

Adult medical and surgical intensive care unit of a teaching hospital.

PATIENTS

One hundred twenty-eight patients who were intubated for >24 hrs with a cuff leak volume <24% of tidal volume and met weaning criteria.

INTERVENTIONS

: Patients were randomized into a placebo group (control, n = 43) receiving four injections of normal saline every 6 hrs, a 4INJ group (n = 42) receiving four injections of methylprednisolone sodium succinate, or a 1INJ group (n = 42) receiving one injection of the corticosteroid followed by three injections of normal saline. Cuff volume was assessed 1 hr after each injection, and extubation was performed 1 hr after the last injection. Postextubation stridor was confirmed by examination using bronchoscopy or laryngoscopy.

MEASUREMENTS AND MAIN RESULTS

The incidences of postextubation stridor were lower both in the 1INJ and the 4INJ groups than in the control group (11.6% and 7.1% vs. 30.2%, both p < .05), whereas there was no difference between the two treated groups (p = .46). The cuff leak volume increased after the second and fourth injection in the 4INJ group and after a second injection in the 1INJ group compared with the control group (both p < .05).

CONCLUSIONS

A reduced cuff leak volume is a reliable indicator to identify patients at high risk to develop stridor. Treatment with a single or multiple injections of methylprednisolone can effectively reduce the occurrence of postextubation stridor.

Subacute airway obstruction from a tracheal mucosal flap

We report the case of a 15-year-old girl with a near fatal obstructive tracheal lesion following tracheal intubation. The patient developed stridor and acute respiratory distress 29 h following tracheal extubation, after 35 h intubation in the intensive care unit. The failure of conventional management of stridor, including re-intubation, to provide a satisfactory airway prompted an urgent bronchoscopy, which revealed a tracheal mucosal flap causing 80% obstruction of the subglottic trachea. The fibreoptic bronchoscope allowed careful placement of a tracheal tube distal to the obstruction. The patient eventually made a full recovery. The low incidence of similar lesions and the lack of distinguishing clinical features from other causes of post-extubation stridor make diagnosis and appropriate management of this life-threatening condition difficult. We discuss how early consideration of the diagnosis and optimal initial management reduce the risk of an adverse outcome.

Time of non-invasive ventilation

Non-invasive ventilation (NIV) is a safe, versatile and effective technique that can avert side effects and complications associated with endotracheal intubation. The success of NIV relies on several factors, including the type and severity of acute respiratory failure, the underlying disease, the location of treatment, and the experience of the team. The time factor is also important. NIV is primarily used to avert the need for endotracheal intubation in patients with early-stage acute respiratory failure and post-extubation respiratory failure. It can also be used as an alternative to invasive ventilation at a more advanced stage of acute respiratory failure or to facilitate the process of weaning from mechanical ventilation. NIV has been used to prevent development of acute respiratory failure or post-extubation respiratory failure. The number of days of NIV and hours of daily use differ, depending on the severity and course of the acute respiratory failure and the timing of application. In this review article, we analyse, compare and discuss the results of studies in which NIV was applied at various times during the evolution of acute respiratory failure.

Association between Adrenal Insufficiency and Ventilator Weaning

RATIONALE

Adrenal insufficiency is a common disorder in critically ill patients with mechanical ventilation and is usually associated with higher mortality and poor clinical outcome.

OBJECTIVES

To determine whether stress dose corticosteroid supplementation can improve ventilator weaning and clinical outcome in patients with adrenal insufficiency.

METHODS

A prospective, randomized, placebo controlled, double-blinded study was conducted in the intensive care unit of a tertiary teaching hospital. A total of 93 mechanically ventilated patients were enrolled in the ventilator weaning trial. Adrenal function was assessed in all patients. Patients with adrenal insufficiency were randomized to the treatment group (50 mg intravenous hydrocortisone every 6 h) and the placebo group.

MEASUREMENTS AND MAIN RESULTS

The successful ventilator weaning percentage was significantly higher in the adequate adrenal reserve group (88.4%) and in the stress dose hydrocortisone treatment group (91.4%) than in the placebo group (68.6%). The weaning period was shorter in the hydrocortisone treatment group than in the placebo group. No significant adverse effects were observed in the corticosteroid treatment group.

CONCLUSIONS

For patients with respiratory failure, early identification of adrenal insufficiency and appropriate supplementation with stress dose hydrocortisone increase the success of ventilator weaning and shortens the weaning period.

The cuff-leak test is a simple tool to verify severe laryngeal edema in patients undergoing long-term mechanical ventilation

OBJECTIVE

The cuff-leak test has been proposed as a simple tool to clinically predict stridor or respiratory distress secondary to laryngeal edema following extubation. However, the true incidence of laryngeal edema in patients on long-term mechanical ventilation is uncertain. The relationship between upper airway obstruction (detected by video bronchoscopy) and the cuff-leak test value for patients with prolonged translaryngeal intubation during percutaneous dilatational tracheostomy (PDT) was investigated.

DESIGN

Prospective, clinical investigation.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Ninety-five patients with prolonged translaryngeal intubation requiring PDT were enrolled during a 12-month period.

INTERVENTIONS

Cuff-leak test, PDT, video bronchoscopy.

MEASUREMENTS AND MAIN RESULTS

The average duration of translaryngeal intubation was 28.1 +/- 17.6 days. The incidence of severe laryngeal edema was 36.8% (35/95). We chose 140 mL as the threshold cuff-leak volume below which edema is indicated. The rate of cuff-leak test positivity was 38.9% (37/95). The sensitivity and the specificity of the test were 88.6% and 90.0%, respectively. The positive and negative predictive values were 83.8% and 93.1%, respectively. Patients who developed severe laryngeal edema had a smaller leak volume than those who did not, expressed in absolute values (53.9 +/- 56.2 vs. 287.9 +/- 120.0 mL; p < .001) or in relative values (10.1 +/- 10.2 vs. 55.3 +/- 22.7%, p < .001). The occurrence of severe laryngeal edema was not associated with age, gender, body weight, respiratory failure due to pneumonia, duration of translaryngeal intubation, endotracheal tube diameter, Acute Physiology and Chronic Health Evaluation II score, or history of self-extubation.

CONCLUSIONS

A reduced cuff-leak volume measured before PDT may signal the presence of severe laryngeal edema in patients on long-term mechanical ventilation.

Current issues in mechanical ventilation for respiratory failure

The morbidity and mortality associated with respiratory failure is, to a certain extent, iatrogenic. Mechanical ventilation, although the mainstay of treatment for respiratory distress syndrome, can result in physical trauma to lung tissue (ventilator-induced lung injury [VILI]). Strategies to alleviate VILI are often termed lung-protective strategies and are aimed at reducing overstretching and shear stresses associated with repetitive alveolar collapse and reopening. Lower tidal volumes during ventilation, maintenance of positive-end expiratory pressure, and high-frequency ventilation are the best-studied lung-protective strategies that appear to reduce VILI. Faster withdrawal from mechanical ventilation could also improve outcomes and lower the costs associated with care. To enhance the success of weaning from mechanical ventilation, the cooperative efforts of physicians and respiratory therapists are needed. These efforts involve the initiation of spontaneous-breathing trials, implementation of systematic weaning protocols, and optimization of individual patient interventions.

Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients

OBJECTIVE

Compared with standard medical therapy (SMT), noninvasive ventilation (NIV) does not reduce the need for reintubation in unselected patients who develop respiratory failure after extubation. The goal of this study was to assess whether early application of NIV, immediately after extubation, is effective in preventing postextubation respiratory failure in an at-risk population.

DESIGN

Multiple-center, randomized controlled study.

SETTING

Multiple hospitals.

PATIENTS

Ninety-seven consecutive patients with similar baseline characteristics, requiring >48 hrs of mechanical ventilation and considered at risk of developing postextubation respiratory failure (i.e., patients who had hypercapnia, congestive heart failure, ineffective cough and excessive tracheobronchial secretions, more than one failure of a weaning trial, more than one comorbid condition, and upper airway obstruction).

INTERVENTIONS

After a successful weaning trial, the patients were randomized to receive NIV for > or = 8 hrs a day in the first 48 hrs or SMT. Primary outcome was the need for reintubation according to standardized criteria. Secondary outcomes were intensive care unit and hospital mortality, as well as time spent in the intensive care unit and in hospital.

MEASUREMENTS AND MAIN RESULTS

Compared with the SMT group, the NIV group had a lower rate of reintubation (four of 48 vs. 12 of 49; p = .027). The need for reintubation was associated with a higher risk of mortality (p < .01). The use of NIV resulted in a reduction of risk of intensive care unit mortality (-10%, p < .01), mediated by the reduction for the need of reintubation.

CONCLUSIONS

NIV was more effective than SMT in preventing postextubation respiratory failure in a population considered at risk of developing this complication.

Noninvasive positive pressure ventilation in the intensive care unit: A concise review

OBJECTIVE

To critically assess available high-level clinical studies regarding use of noninvasive positive pressure ventilation in varied intensive care unit settings.

DATA SOURCE

Search of pertinent articles within Ovid MEDLINE from 1975 to 2005, CINAHL from 1982 to 2005, EMBASE from 1988 to 2005, and Web of Science from 1993 to 2005.

STUDY SELECTION

Randomized, controlled clinical trials and cohort studies and observational studies the authors consider important or novel.

DATA EXTRACTION/SYNTHESIS

Performed equally by both authors with the use of an Excel data spreadsheet.

CONCLUSION

There is abundant level I evidence supporting the use of noninvasive positive pressure ventilation in such critical care settings as acute hypercapnic respiratory failure, particularly related to chronic obstructive pulmonary disease, and acute cardiogenic pulmonary edema. We also report on other clinical scenarios in which the data may be somewhat less compelling, but evidence favors a noninvasive positive pressure ventilation trial. Some well designed studies suggest that noninvasive positive pressure ventilation is not an appropriate intervention for patients who have failed endotracheal extubation.

High body mass index and long duration of intubation increase post-extubation stridor in patients with mechanical ventilation

Approximately 20% of mechanically ventilated patients experience post-extubation stridor (PES) and reintubation, which subsequently may lead to an increased risk of morbidity and mortality. The risk of PES development is significantly higher in obese patients. Low air leakage between the endotracheal tube and the trachea, following cuff deflation, may indicate a higher risk for the development of PES. The aim of this study is to identify the relationship between body mass index (BMI) and PES using the cuff-leak test in patients intubated in the respiratory intensive care unit. A total of 67 consecutive intubations on 56 different ventilated patients were included in this study. The mean age was 63.6 +/- 12.1 years and 84% of the patients were male. PES developed in seven patients (10.4%). The mean cuff-leak volume was 395 +/- 187 ml in non-PES patients and 240 +/- 93 ml in PES patients (p = 0.023). The mean BMI was 36 +/- 13 kg/m2 in PES patients and 24 +/- 7 kg/m2 in non-PES patients (p = 0.046). BMI > 26.5 kg/m2 (OR: 1.2), low cuff-leak volume (< 283 ml) and mechanical ventilation required for more than 5 days (OR: 0.9) were independent variables for PES occurrence. We therefore suggest that non-obese patients, short-term intubated patients and those having a high air leakage around the endotracheal tube could be extubated without much difficulty.

Early noninvasive ventilation averts extubation failure in patients at risk: a randomized trial

RATIONALE

Respiratory failure after extubation and reintubation is associated with increased morbidity and mortality.

OBJECTIVES

To assess the efficacy of noninvasive ventilation in averting respiratory failure after extubation in patients at increased risk.

METHODS

A prospective randomized controlled trial was conducted in 162 mechanically ventilated patients who tolerated a spontaneous breathing trial after recovery from the acute episode but had increased risk for respiratory failure after extubation. Patients were randomly allocated after extubation to receive noninvasive ventilation for 24 h (n = 79), or conventional management with oxygen therapy (control group, n = 83).

MEASUREMENTS AND MAIN RESULTS

The primary end-point variable was the decrease in respiratory failure after extubation. In the noninvasive ventilation group, respiratory failure after extubation was less frequent (13, 16 vs. 27, 33%; p = 0.029) and the intensive care unit mortality was lower (2, 3 versus 12, 14%; p = 0.015). However, 90-d survival did not change significantly between groups. Separate analyses of patients without and with hypercapnia (arterial CO(2) tension greater than 45 mm Hg) during the spontaneous breathing trial showed that noninvasive ventilation improved intensive care unit mortality (0 vs. 4, 18%; p = 0.035) and 90-d survival (p = 0.006) in hypercapnic patients only; of them, 98% had chronic respiratory disorders.

CONCLUSIONS

The early use of noninvasive ventilation averted respiratory failure after extubation and decreased intensive care unit mortality among patients at increased risk. The beneficial effect of noninvasive ventilation in improving survival of hypercapnic patients with chronic respiratory disorders warrants a new prospective clinical trial.