Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the American College of Chest Physicians; the American Association for Respiratory Care; and the American College of Critical Care Medicine

Respiratory weakness is associated with limb weakness and delayed weaning in critical illness

OBJECTIVE

Although critical illness neuromyopathy might interfere with weaning from mechanical ventilation, its respiratory component has not been investigated. We designed a study to assess the level of respiratory muscle weakness emerging during the intensive care unit stay in mechanically ventilated patients and to examine the correlation between respiratory and limb muscle strength and the specific contribution of respiratory weakness to delayed weaning.

DESIGN

Prospective observational study.

SETTING

Two medical, one surgical, and one medicosurgical intensive care units in two university hospitals and one university- affiliated hospital.

PATIENTS

A total of 116 consecutive patients were enrolled after >or=7 days of mechanical ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Maximal inspiratory and expiratory pressures and vital capacity were measured via the tracheal tube on the first day of return to normal consciousness. Muscle strength was measured using the Medical Research Council score. After standardized weaning, successful extubation was defined as the day from which mechanical ventilatory support was no longer required within the next 15 days. The median value (interquartile range) of maximal inspiratory pressure was 30 (20-40) cm H2O, maximal expiratory pressure was 30 (20-50) cm H2O, and vital capacity was 11.1 (6.3-19.8) mL/kg. Maximal inspiratory pressure, maximal expiratory pressure, and vital capacity were significantly correlated with the Medical Research Council score. The median time (interquartile range) from awakening to successful extubation was 6 (1-17) days. Low maximal inspiratory pressure (hazard ratio, 1.86; 95% confidence interval, 1.07-3.23), maximal expiratory pressure (hazard ratio, 2.18; 95% confidence interval, 1.44-3.84), and Medical Research Council score (hazard ratio, 1.96; 95% confidence interval, 1.27-3.02) were independent predictors of delayed extubation. Septic shock before awakening was significantly associated with respiratory weakness (odds ratio, 3.17; 95% confidence interval, 1.17-8.58).

CONCLUSIONS

Respiratory and limb muscle strength are both altered after 1 wk of mechanical ventilation. Respiratory muscle weakness is associated with delayed extubation and prolonged ventilation. In our study, septic shock is a contributor to respiratory weakness.

Admission Time and Outcomes of Patients in A Medical Intensive Care Unit

Studies have shown that weekend or night admissions to intensive care units (ICUs) are associated with increased mortality in critically ill patients. Our study aimed to evaluate the effects of admission time and day on patient outcomes in a medical ICU equipped with patient management guide-lines, and staffed by intensivists on call for 24 hours, who led the morning rounds on all days of the week but did not stay in-house overnight. The study enrolled 611 consecutive patients admitted to a 26-bed medical ICU in a university hospital during a 7-month period. We divided them into two groups, which we labeled as "office hours" (08:00-18:00 on weekdays) and "non-office hours" (18:00-08:00 on weekdays, and all times on weekends) according to their ICU admission times. The clinical outcomes were compared between the groups. The effects of admission on weekends, at night, and various days of the week on hospital mortality were also evaluated. Our results showed that there were no significant differences in ICU and hospital mortalities between patients admitted during office hours and those admitted during non-office hours (27.2% vs. 27.4%, p = 1.000; 38.9% vs. 37.6%, p = 0.798). The ICU length of stay, ICU-free time within 21 days, and length of stay in the hospital were also comparable in both groups. Among the 392 patients requiring mechanical ventilation, the ventilator outcomes were not significantly different between those in the office-hour group and the non-office-hour group. Multivariate logistic regression analyses showed that the adjusted odds of hospital mortality were not significantly higher for patients admitted to our ICU on weekends, at night, or on any days of the week. In conclusion, our results showed that non-office-hour admissions to our medical ICU were not associated with poorer ICU, hospital, and ventilator outcomes, compared with office-hour admissions. Neither were time of day and day of the week admissions to our ICU associated with significant differences in hospital mortality.

Boussignac continuous positive airway pressure for weaning with tracheostomy tubes

BACKGROUND

In patients who are weaned with a tracheostomy tube (TT), continuous positive airway pressure (CPAP) is frequently used. Dedicated CPAP systems or ventilators with bulky tubing are usually applied. However, CPAP can also be effective without a ventilator by the disposable Boussignac CPAP (BCPAP) system that is normally used with face masks.

OBJECTIVE

It was the aim of this audit to evaluate the feasibility of low-level BCPAP in patients who were weaned with a TT.

METHODS

All patients at our surgical intensive care unit who received a TT for weaning were considered for application of BCPAP. Once patients had received minimal pressure support from the mechanical ventilator, the BCPAP device was connected to the TT three times a day for 30 min with pressure set to 3-5 cm H(2)O, FiO(2) at 0.4 and with humidification. BCPAP was then gradually extended to 24 h/day. Patient acceptance, complications and outcome were recorded.

RESULTS

58 patients received a TT to facilitate weaning. They had a median stay of 52 days in the intensive care unit during which they had an endotracheal tube for 22 days and a TT for 28 days. 50 of these patients (86%) received BCPAP for a median of 16 days. The lightweight BCPAP system was well tolerated without tube obstructions or accidental decannulations and may have contributed to patient mobility. No patient remained on ventilatory support after hospital discharge. In-hospital and 1-year survival were 86 and 71%, respectively.

CONCLUSIONS

BCPAP is a feasible and safe method for weaning tracheostomy patients.

Tracheostomy in the critically ill: indications, timing and techniques

PURPOSE OF REVIEW

Tracheostomy is one of the most common procedures performed in the intensive care unit. Indications, risks, benefits, timing and technique of the procedure, however, remain controversial. The decision of when and how to perform a tracheostomy is often subjective, but must be individualized to the patient. The following review gives an update on recent literature related to tracheostomy in the critically ill.

RECENT FINDINGS

Surprisingly, few data are available on the current practice of tracheostomy in the intensive care unit setting. Very few trials address this issue in a prospective, randomized fashion (randomized controlled trial). Most reports include small numbers representing a heterogeneous population, describing contrary results and precluding any definite conclusions. Evidence seems to suggest that early tracheostomy, however, might be preferable in selected patients.

SUMMARY

Due to increased experience and advanced techniques, percutaneous tracheostomy has become a popular, relatively safe procedure in the intensive care unit. The question of appropriate timing, however, has not been definitely answered with a randomized controlled trial. Instead, a number of retrospective studies and a single prospective study have shed some light on this issue. Most reports favor the performance of tracheostomy within 10 days of respiratory failure.

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.

Mechanical ventilation in ARDS: a state-of-the-art review

Mechanical ventilation is an essential component of the care of patients with ARDS, and a large number of randomized controlled clinical trials have now been conducted evaluating the efficacy and safety of various methods of mechanical ventilation for the treatment of ARDS. Low tidal volume ventilation (</= 6 mL/kg predicted body weight) should be utilized in all patients with ARDS as it is the only method of mechanical ventilation that, to date, has been shown to improve survival. High positive end-expiratory pressure, alveolar recruitment maneuvers, and prone positioning may each be useful as rescue therapy in a patient with severe hypoxemia, but these methods of ventilation do not improve survival for the wide population of patients with ARDS. Although not specific to the treatment of ARDS, protocol-driven weaning that utilizes a daily spontaneous breathing trial and ventilation in the semirecumbent position have proven benefits and should be used in the management of ARDS patients.

Is tracheostomy associated with better outcomes for patients requiring long-term mechanical ventilation?

OBJECTIVE

To evaluate the effect of tracheostomy on intensive care unit (ICU) and in-hospital mortality for patients requiring prolonged (> 3 days) mechanical ventilation (MV).

DESIGN, SETTING, AND PATIENTS

We retrospectively reviewed the charts of all consecutive patients admitted to our 18-bed tertiary care ICU over 3 yrs (2002-2004) and who received prolonged MV. Outcomes of tracheostomized and nontracheostomized patients were evaluated using univariable and multivariable logistic-regression analyses and by constructing a case-control cohort using a propensity score for performing tracheostomy. MV duration for controls was at least equal to the time from MV onset to tracheostomy for the matched case.

MEASUREMENTS AND MAIN RESULTS

Of the 506 patients requiring prolonged MV, 166 were tracheostomized after a median of 12 days of MV. Nontracheostomized patients had higher ICU (42% vs. 33%, p = .06) and in-hospital (48% vs. 37%, p = .03) mortality rates and shorter MV durations and ICU lengths of stay. Performing a tracheostomy (odds ratio, 0.58; 95% CI, 0.37-0.90) was independently associated with a lower probability of ICU death, even after adjusting for other important prognostic factors. No significant differences were detected between the 120 cases and their matched controls regarding ICU admission and day-3 clinical characteristics. After conditional logistic-regression analysis, tracheostomy was associated with lower risk of ICU (odds ratio, 0.47; 95% CI, 0.24-0.89) and in-hospital (odds ratio, 0.48; 95% CI, 0.25-0.90) death.

CONCLUSIONS

Tracheostomy performed in our ICU for long-term MV patients was associated with lower ICU and in-hospital mortality rates, even after carefully controlling for ICU admission and day-3 clinical and physiologic differences between groups. Whether these results reflect that physicians were able to adequately select for tracheostomy patients who, despite having similar physiologic and demographic variables, had the highest probabilities of survival or that the procedure itself really affected the outcomes of these patients will remain speculative.

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.

Mechanical ventilation: a tutorial for pharmacists

Mechanical ventilation is an integral part of the critical care environment and requires orchestration by a multidisciplinary team of clinicians to optimize therapeutic outcomes. By tradition, pharmacists have not been included on this team since this therapeutic modality is not considered relevant to their scope of practice. However, pharmacists play a critical role in the management of patients receiving mechanical ventilation by assisting in the development of institutional guidelines and protocols, by maintaining accuracy of prescribed drug dosages, by monitoring for drug-drug and drug-disease interactions, by assisting with alternative drug selections, and by maintaining continued quality assessment of drug administration. Pharmacists able to understand and integrate mechanical ventilation with the pharmacotherapeutic needs of patients are better qualified practitioners. The goal of this article is to help clinical pharmacists better understand the complexities of mechanical ventilation and to apply this information in optimizing delivery of pharmaceutical agents to critical care patients.

Implementation of a weaning algorithm in postoperative cardiac ICU: simple enough to be implemented in a ventilator software

OBJECTIVE

The aim of this study was to test the efficacy of a respiratory weaning algorithm (WA) in postoperative cardiac surgery patients. This algorithm was made simple enough to be implemented in medium-end ventilator software.

PATIENTS

Twenty consecutive postoperative patients who underwent scheduled cardiac surgery with normal postoperative haemodynamic and respiratory status.

METHODS

A 3 step WA (Controlled Mode Ventilation, Pressure Support (PS) at +20 cmH2O and at +10 cmH2O) was applied every 15 minute by the same investigator. A 15 minute period of respiratory stability at one step led to commute to a step ahead until patient was judged "ready for extubation" (RFE, i.e. stable during 15 min under PS +10 cmH2O). Once reaching this time, the patient was left under PS +10 until nurse and doctors in charge decided extubation according to our routine clinical criteria.

RESULTS

the patients were routinely extubated, in average 187+/-169 min later than when judged RFE by the algorithm. Heart rate (P<0.05) and mean arterial pressure rose when they reached the time of effective extubation, by comparison to the RFE time point.

CONCLUSION

A WA has clinical advantage in cardiac surgery as it reduces respiratory weaning duration. It helps to avoiding haemodynamic stress related to delayed extubation. Such an algorithm is simple enough to be implemented in medium-end ventilators.

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.

The effect of exogenous surfactant in patients with lung contusions and acute lung injury

OBJECTIVE

To investigate the acute effect of surfactant replacement in multiple-trauma patients with lung contusion and acute lung injury.

DESIGN AND SETTING

Prospective randomized clinical trial in the 14-bed ICU of a 750-bed university hospital.

PATIENTS AND PARTICIPANTS

Sixteen ventilated trauma patients with severe refractory hypoxemia (PaO(2)/FIO(2)<150 mmHg) and lung contusions.

INTERVENTIONS

Patients were randomly assigned to either surfactant administration (n=8) or standard treatment (n=8). A single dose of natural bovine surfactant was instilled bronchoscopically in the involved lung areas; each segmental bronchus received (200/19) mg/kg body weight.

MEASUREMENTS AND RESULTS

The surfactant group demonstrated an acute improvement in oxygenation after surfactant replacement compared both to control group and to baseline values. In the surfactant group PaO(2)/FIO(2) increased from 100+/-20 mmHg at baseline to 140+/-20 (6 h), 163+/-26 (12 h), and 187+/-30 mmHg (24h). Compliance increased from 30 to 36 ml/cmH(2)O at 6 h after administration, and this increase remained significant at the 24, 48, and 72 h time points. The surfactant group demonstrated a higher response to recruitment maneuvers than the control group at 6 h. The mean duration of ventilatory support was 5.6 +/-2.6 days in the surfactant group and 8.1+/-2.4 days in the control group.

CONCLUSIONS

Surfactant replacement was well tolerated in patients with lung contusions and severe hypoxemia and resulted in improved oxygenation and compliance.

Respiratory management of inhalation injury

Advances in the care of patients with major burns have led to a reduction in mortality and a change in the cause of their death. Burn shock, which accounted for almost 20 percent of burn deaths in the 1930s and 1940s, is now treated with early, vigorous fluid resuscitation and is only rarely a cause of death. Burn wound sepsis, which emerged as the primary cause of mortality once burn shock decreased in importance, has been brought under control with the use of topical antibiotics and aggressive surgical debridement. Inhalation injury has now become the most frequent cause of death in burn patients. Although mortality from smoke inhalation alone is low (0-11 percent), smoke inhalation in combination with cutaneous burns is fatal in 30 to 90 percent of patients. It has been recently reported that the presence of inhalation injury increases burn mortality by 20 percent and that inhalation injury predisposes to pneumonia. Pneumonia has been shown to independently increase burn mortality by 40 percent, and the combination of inhalation injury and pneumonia leads to a 60 percent increase in deaths. Children and the elderly are especially prone to pneumonia due to a limited physiologic reserve. It is imperative that a well organized, protocol driven approach to respiratory care of inhalation injury be utilized so that improvements can be made and the morbidity and mortality associated with inhalation injury be reduced.

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.

Variations in rates of tracheostomy in the critically ill trauma patient

OBJECTIVE

The utility of tracheostomy to expedite weaning and prevent complications in patients with acute respiratory failure is actively debated, with many physicians holding strong opinions regarding the value and timing of this intervention. We postulated that these opinions would be reflected in significant variation in tracheostomy rates across centers. Thus, we set out explore the extent and potential sources of this variation among injured patients cared for in trauma centers in the United States.

DESIGN

This is a retrospective cohort study. We used stratification and hierarchical multivariate analysis to evaluate the effect of patient and institutional characteristics on tracheostomy rates and variance decomposition to determine the proportion of variance across institutions explained by patient characteristics.

SETTING

Intensive care units within trauma centers participating in the National Trauma Databank.

PATIENTS

Injured patients admitted over the years 2001-2003, age >/=16 yrs, with an Injury Severity Score >/=9 and a diagnosis of acute respiratory failure, excluding patients with burn injuries and those with a severe injury to the face or neck who might require tracheostomy for maintenance of an airway.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 17,523 patients meeting inclusion criteria: 4,146 (24%) underwent tracheostomy. The mean tracheostomy rate across centers was 19.6 per 100 hospital admissions with a range of 0-59. This variation persisted after stratification by age, injury mechanism, and severity. Although several patient and injury characteristics were predictive of tracheostomy, there were no identifiable institutional characteristics associated with tracheostomy. Patient characteristics accounted for only 14% of the variance across centers.

CONCLUSIONS

There is significant unexplained variation in the rates of tracheostomy in critically injured patients with acute respiratory failure. This variation might reflect preconceived notions of efficacy among physicians practicing in the absence of evidence to guide care. The variation provides evidence of equipoise and emphasizes the need for a well-conducted randomized controlled trial to evaluate the utility of this procedure.

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.

Imposed work of breathing during high-frequency oscillatory ventilation: a bench study

Introduction

The ventilator and the endotracheal tube impose additional workload in mechanically ventilated patients breathing spontaneously. The total work of breathing (WOB) includes elastic and resistive work. In a bench test we assessed the imposed WOB using 3100 A/3100 B SensorMedics high-frequency oscillatory ventilators.

Methods

A computer-controlled piston-driven test lung was used to simulate a spontaneously breathing patient. The test lung was connected to a high-frequency oscillatory ventilation (HFOV) ventilator by an endotracheal tube. The inspiratory and expiratory airway flows and pressures at various places were sampled. The spontaneous breath rate and volume, tube size and ventilator settings were simulated as representative of the newborn to adult range. The fresh gas flow rate was set at a low and a high level. The imposed WOB was calculated using the Campbell diagram.

Results

In the simulations for newborns (assumed body weight 3.5 kg) and infants (assumed body weight 10 kg) the imposed WOB (mean ± standard deviation) was 0.22 ± 0.07 and 0.87 ± 0.25 J/l, respectively. Comparison of the imposed WOB in low and high fresh gas flow rate measurements yielded values of 1.63 ± 0.32 and 0.96 ± 0.24 J/l (P = 0.01) in small children (assumed body weight 25 kg), of 1.81 ± 0.30 and 1.10 ± 0.27 J/l (P < 0.001) in large children (assumed body weight 40 kg), and of 1.95 ± 0.31 and 1.12 ± 0.34 J/l (P < 0.01) in adults (assumed body weight 70 kg). High peak inspiratory flow and low fresh gas flow rate significantly increased the imposed WOB. Mean airway pressure in the breathing circuit decreased dramatically during spontaneous breathing, most markedly at the low fresh gas flow rate. This led to ventilator shut-off when the inspiratory flow exceeded the fresh gas flow.

Conclusion

Spontaneous breathing during HFOV resulted in considerable imposed WOB in pediatric and adult simulations, explaining the discomfort seen in those patients breathing spontaneously during HFOV. The level of imposed WOB was lower in the newborn and infant simulations, explaining why these patients tolerate spontaneous breathing during HFOV well. A high fresh gas flow rate reduced the imposed WOB. These findings suggest the need for a demand flow system based on patient need allowing spontaneous breathing during HFOV.

Tracheotomy does not affect reducing sedation requirements of patients in intensive care--a retrospective study

Introduction

Translaryngeal intubated and ventilated patients often need sedation to treat anxiety, agitation and/or pain. Current opinion is that tracheotomy reduces sedation requirements. We determined sedation needs before and after tracheotomy of intubated and mechanically ventilated patients.

Methods

We performed a retrospective analysis of the use of morphine, midazolam and propofol in patients before and after tracheotomy.

Results

Of 1,788 patients admitted to our intensive care unit during the study period, 129 (7%) were tracheotomized. After the exclusion of patients who received a tracheotomy before or at the day of admittance, 117 patients were left for analysis. The daily dose (DD; the amount of sedatives for each day) divided by the mean daily dose (MDD; the mean amount of sedatives per day for the study period) in the week before and the week after tracheotomy was 1.07 ± 0.93 DD/MDD versus 0.30 ± 0.65 for morphine, 0.84 ± 1.03 versus 0.11 ± 0.46 for midazolam, and 0.62 ± 1.05 versus 0.15 ± 0.45 for propofol (p < 0.01). However, when we focused on a shorter time interval (two days before and after tracheotomy), there were no differences in prescribed doses of morphine and midazolam. Studying the course in DD/MDD from seven days before the placement of tracheotomy, we found a significant decline in dosage. From day -7 to day -1, morphine dosage (DD/MDD) declined by 3.34 (95% confidence interval -1.61 to -6.24), midazolam dosage by 2.95 (-1.49 to -5.29) and propofol dosage by 1.05 (-0.41 to -2.01). After tracheotomy, no further decrease in DD/MDD was observed and the dosage remained stable for all sedatives. Patients in the non-surgical and acute surgical groups received higher dosages of midazolam than patients in the elective surgical group. Time until tracheotomy did not influence sedation requirements. In addition, there was no significant difference in sedation between different patient groups.

Conclusion

In our intensive care unit, sedation requirements were not further reduced after tracheotomy. Sedation requirements were already sharply declining before tracheotomy was performed.

Variable performance of weaning-predictor tests: role of Bayes' theorem and spectrum and test-referral bias

OBJECTIVE

We examined whether variation in reported reliability of the frequency-to-tidal volume ratio (f/V(T)) in predicting weaning success is explained by spectrum and test-referral bias, as reflected by variation in pretest probability of success.

DESIGN

Two authors extracted data from all studies on reliability of f/V(T) as a weaning predictor.

RESULTS

Prevalence of successful weaning in studies of f/V(T) revealed significant heterogeneity; mean success rate was 0.75. The heterogeneity and high success rate reflects occurrence of spectrum bias, suggested by the lower value of f/V(T) in subsequent studies than in the original report (77.4 vs. 89.1) and test-referral bias, suggested by lower specificity of f/V(T) in subsequent studies than in the original report (0.52 vs. 0.64). When data from studies in the ACCP Task Force's meta-analysis of studies on f/V(T) were entered into a Bayesian model with pretest probability (prevalence of success) as the operating point, observed posttest probabilities were closely correlated with values predicted by the original report on f/V(T): positive-predictive value r = 0.86 and negative-predictive value r = 0.82. Average sensitivity, the most precise measure of screening-test reliability, was 0.87 +/- 0.14 and average specificity 0.52 +/- 0.26.

CONCLUSIONS

Much of the heterogeneity in performance of f/V(T) can be explained by variation in pretest probability of successful outcome, which may be secondary to spectrum and test-referral bias. The average sensitivity of 0.87 indicates that f/V(T) is a reliable screening test for successful weaning.

Unloading work of breathing during high-frequency oscillatory ventilation: a bench study

Introduction

With the 3100B high-frequency oscillatory ventilator (SensorMedics, Yorba Linda, CA, USA), patients' spontaneous breathing efforts result in a high level of imposed work of breathing (WOB). Therefore, spontaneous breathing often has to be suppressed during high-frequency oscillatory ventilation (HFOV). A demand-flow system was designed to reduce imposed WOB.

Methods

An external gas flow controller (demand-flow system) accommodates the ventilator fresh gas flow during spontaneous breathing simulation. A control algorithm detects breathing effort and regulates the demand-flow valve. The effectiveness of this system has been evaluated in a bench test. The Campbell diagram and pressure time product (PTP) are used to quantify the imposed workload.

Results

Using the demand-flow system, imposed WOB is considerably reduced. The demand-flow system reduces inspiratory imposed WOB by 30% to 56% and inspiratory imposed PTP by 38% to 59% compared to continuous fresh gas flow. Expiratory imposed WOB was decreased as well by 12% to 49%. In simulations of shallow to normal breathing for an adult, imposed WOB is 0.5 J l^-1 at maximum. Fluctuations in mean airway pressure on account of spontaneous breathing are markedly reduced.

Conclusion

The use of the demand-flow system during HFOV results in a reduction of both imposed WOB and fluctuation in mean airway pressure. The level of imposed WOB was reduced to the physiological range of WOB. Potentially, this makes maintenance of spontaneous breathing during HFOV possible and easier in a clinical setting. Early initiation of HFOV seems more possible with this system and the possibility of weaning of patients directly on a high-frequency oscillatory ventilator is not excluded either.

Is there a "right" way to wean my patient from the ventilator? A critical appraisal of Randolph et al: Effect of mechanical ventilator weaning protocols on respiratory outcomes in infants and children: A randomized controlled trial (JAMA 2002; 288:2561-2568)

OBJECTIVE

To review the findings and discuss the implications of mechanical ventilator weaning protocols in children.

DESIGN

A critical appraisal of Randolph et al. Effect of mechanical ventilator weaning protocols on respiratory outcomes in infants and children: A randomized controlled trial. JAMA 2002;288:2561-2568, and literature review.

FINDINGS

There was no difference in ventilator weaning times between children randomized to a ventilator weaning protocol (pressure support, volume support, or no protocol). However, the study did show that increased sedative use during the first 24 hrs of weaning (the only time during which these data were collected) was an important predictor of weaning duration (p < .001) and weaning failure (p = .04).

CONCLUSIONS

The majority of children are weaned from mechanical ventilation over a short period of time. Weaning protocols may not shorten this brief duration of weaning but may have other advantages such as improved collaboration between healthcare team members. Future research into the effects of sedation on weaning from mechanical ventilation is needed in children.

Hemodynamic Changes During Discontinuation of Mechanical Ventilation in Medical Intensive Care Unit Patients

• Background Cardiac dysfunction can prevent successful discontinuation of mechanical ventilation. Critically ill patients may have undetected cardiac disease, and cardiac dysfunction can be produced or exacerbated by underlying pathophysiology.

• Objective To describe and compare hemodynamic function and cardiac rhythm during baseline mechanical ventilation with function and rhythm during a trial of continuous positive airway pressure in medical intensive care patients.

• Methods A convenience sample of 43 patients (53% men; mean age 51.1 years) who required mechanical ventilation were recruited for this pilot study. Cardiac output, stroke volume, arterial blood pressure, heart rate, cardiac rhythm, and plasma catecholamine levels were measured during mechanical ventilation and during a trial of continuous positive airway pressure.

• Results One third of the patients had difficulty discontinuing mechanical ventilation. Successful patients had significantly increased cardiac output and stroke volume without changes in heart rate or arterial pressure during the trial of continuous positive airway pressure. Unsuccessful patients had no significant changes in cardiac output, stroke volume, or heart rate but had a significant increase in mean arterial pressure. The 2 groups of patients also had different patterns in ectopy. Concurrently, catecholamine concentrations decreased in the successful patients and significantly increased in the unsuccessful patients during the trial.

• Conclusions Patterns of cardiac function and plasma catecholamine levels differed between patients who did or did not achieve spontaneous ventilation with a trial of continuous positive airway pressure. Cardiac function must be systematically considered before and during the return to spontaneous ventilation to optimize the likelihood of success.

Acceptable respiratory physiologic limits for children during weaning from mechanical ventilation

OBJECTIVE

The aim of this survey was to characterize the physiological limits considered appropriate during weaning from mechanical ventilation in children.

DESIGN

Two hundred twenty-two (222) intensivists from 63 pediatric intensive care units (PICUs) were asked to provide the limits they considered acceptable for respiratory rate (RR), tidal volume (V(T)) and end-tidal CO(2) (PetCO(2)) during weaning from mechanical ventilation of a 3-month-old, a 2-year-old and a 10-year-old patient.

SETTING

Pediatric intensivists working in Canada, France, Switzerland and Belgium.

PATIENTS

None.

INTERVENTIONS

None.

RESULTS

Ninety-seven intensivists (43%) from 49 PICUs responded to the survey. The median minimal RR (25th;75th percentile) was: 20 breaths per minute (bpm) (15;25) for the 3-month-old, 15 bpm (10;15) for the 2-year-old and 10 bpm (10;15) for the 10-year-old patient. The median maximal RR was 50 bpm (40;60) for the 3-month-old, 40 bpm (30;40) for the 2-year-old and 30 bpm (30;40) for the 10-year-old child. The median minimal V(T) was 5 ml/kg (4;6) for the 3-month-old and 2-year-old patients and 5 ml/kg (5;6) for the 10-year-old. The median maximal PetCO(2) was 55 mmHg (50;60) for the 3-month-old, 50 mmHg (45;50) for the 2-year-old and 50 mmHg (50;55) for the 10-year-old.

CONCLUSION

This survey indicated that acceptable weaning limits are broad, as stated by the responders. We need to organize and consolidate our thinking on weaning children from mechanical ventilation before guidelines can be established.

Intrapulmonary percussive ventilation in tracheostomized patients: a randomized controlled trial

OBJECTIVE

To investigate whether the addition of intrapulmonary percussive ventilation to the usual chest physiotherapy improves gas exchange and lung mechanics in tracheostomized patients.

DESIGN AND SETTING

Randomized multicenter trial in two weaning centers in northern Italy.

PATIENTS AND PARTICIPANTS

46 tracheostomized patients (age 70 +/- 7 years, 28 men, arterial blood pH 7.436 +/- 0.06, PaO(2)/FIO(2) 238 +/- 46) weaned from mechanical ventilation.

INTERVENTIONS

Patients were assigned to two treatment groups performing chest physiotherapy (control), or percussive ventilation (IMP2 Breas, Sweden) 10 min twice/day in addition to chest physiotherapy (intervention).

MEASUREMENTS AND RESULTS

Arterial blood gases, PaO(2)/FIO(2) ratio, and maximal expiratory pressure were assessed every 5th day for 15 day. Treatment complications that showed up in 1 month of follow-up were recorded. At 15 days the intervention group had a significantly better PaO(2)/FIO(2) ratio and higher maximal expiratory pressure; after follow-up this group also had a lower incidence of pneumonia.

CONCLUSIONS

The addition of percussive ventilation to the usual chest physiotherapy regimen in tracheostomized patients improves gas exchange and expiratory muscle performance and reduces the incidence of pneumonia.

A randomized, controlled trial of the role of weaning predictors in clinical decision making

OBJECTIVE

Weaning predictors are often incorporated in protocols to predict weaning outcome for patients on mechanical ventilation. The predictors are used as a decision point in protocols to determine whether a patient may advance to a spontaneous breathing trial. The impact of including predictors in a weaning protocol has not been previously studied. We designed a study to determine the effect of including a weaning predictor (frequency-tidal volume ratio, or f/Vt) in a weaning protocol.

DESIGN

Randomized, blinded controlled trial.

SETTING

Academic teaching hospitals.

PATIENTS

Three hundred and four patients admitted to intensive care units at three academic teaching hospitals.

INTERVENTIONS

Patients were screened daily for measures of oxygenation, cough and secretions, adequate mental status, and hemodynamic stability. Patients were randomized to two groups; in one group the f/Vt was measured but not used in the decision to wean (n = 151), but in the other group, f/Vt was measured and used, using a threshold of 105 breaths/min/L (n = 153). Patients passing the screen received a 2-hr spontaneous breathing trial. Patients passing the spontaneous breathing trial were eligible for an extubation attempt.

MEASUREMENTS AND MAIN RESULTS

Groups were similar with regard to gender, age, and Acute Physiology and Chronic Health Evaluation II score. The median duration for weaning time was significantly shorter in the group where the weaning predictor was not used (2.0 vs. 3.0 days, p = .04). There was no difference with regard to the extubation failure, in-hospital mortality rate, tracheostomy, or unplanned extubation.

CONCLUSIONS

Including a weaning predictor (f/Vt) in a protocol prolonged weaning time. In addition, the predictor did not confer survival benefit or reduce the incidence of extubation failure or tracheostomy. The results of this study indicate that f/Vt should not be used routinely in weaning decision making.

Does sedation practice delay time to extubation?

Criteria for performing a spontaneous breathing trial (SBT) have not been evaluated in controlled trials. An important component of these criteria is neurological status. The objective of this study was to evaluate whether physicians take mental status into consideration before performing an SBT in mechanically ventilated patients.

METHODS

This was a prospective, observational study which included 355 mechanically ventilated patients. Daily assessments were made of whether the patients met criteria for performing a SBT. On the day a patient met the criteria, the level of sedation was evaluated using the Glasgow Coma Scale as modified by Cook and Palma (GCS-Cook) and it was registered whether or not the physician carried out an SBT.

RESULTS

Two hundred and four patients (57%) underwent an SBT on the day they met the criteria (cohort 1) and in 151 patients (cohort 2) the SBT was delayed a median time of 1 day (interquartile range 1-2). There were differences in the GCS-Cook score on the day the criteria were met for performing an SBT (mean 13+/-3 points in cohort 1 versus 9+/-3 points in cohort 2; P<0.001). There were differences (P<0.001) between the cohorts in days of intubation and length of stay in the intensive care unit.

CONCLUSIONS

Neurological status/level of sedation is a factor in the decision whether or not to perform a spontaneous breathing trial.

Effects of physical training on functional status in patients with prolonged mechanical ventilation

BACKGROUND AND PURPOSE

Patients requiring prolonged mechanical ventilation (PMV) are frequently deconditioned because of respiratory failure precipitated by the underlying disease, the adverse effects of medications, and a period of prolonged immobilization. The effects of 6 weeks of physical training on the strength of respiratory and limb muscles, on ventilator-free time, and on functional status in patients requiring PMV were examined.

SUBJECTS

Thirty-nine patients with PMV were initially enrolled in the study and were assigned to either a treatment group (n=20) or a control group (n=19). Three subjects in the treatment group and 4 subjects in the control group died during the 6-week intervention period and thus their data were excluded from the final analysis.

METHODS

Subjects in the treatment group received physical training 5 days a week for 6 weeks. Strength of respiratory and limb muscles, ventilator-free time, and functional status, which was measured by the Barthel Index of Activities of Daily Living (BI) and Functional Independence Measure (FIM), were examined at baseline and at the third and sixth weeks of the study period.

RESULTS

Respiratory and limb muscle strength improved significantly at the third and sixth weeks in the treatment group compared with baseline measurements. Total BI and FIM scores increased significantly in the treatment group and remained unchanged in the control group. Effect sizes of the BI and FIM scores were 2.02 and 1.93, respectively, at the sixth week.

DISCUSSION AND CONCLUSION

The results show that a 6-week physical training program may improve limb muscle strength and ventilator-free time and thus improve functional outcomes in patients requiring PMV.

B-type natriuretic peptide and weaning from mechanical ventilation

OBJECTIVE

Cardiac function and volume status could play a critical role in the setting of weaning failure. B-type natriuretic peptide (BNP) is a powerful marker of cardiac dysfunction. We assessed the value of BNP during the weaning process.

DESIGN, SETTING AND PATIENTS

One hundred and two consecutive patients considered ready to undergo a 1-h weaning trial (T-piece or low-pressure support level) were prospectively included in a medical intensive care unit of a university hospital. Weaning was considered successful if the patient passed the trial and sustained spontaneous breathing for more than 48 h after extubation.

INTERVENTIONS

Plasma BNP was measured just before the trial in all patients, and at the end of the trial in the first 60 patients.

RESULTS

Overall, 42 patients (41.2%) failed the weaning process (37 patients failed the trial and 5 failed extubation). Logistic regression analysis identified high BNP level before the trial and the product of airway pressure and breathing frequency during ventilation as independent risk factors for weaning failure. BNP values were not different at the end of the trial. In nine of the patients in whom the weaning process failed, it succeeded on a later occasion after diuretic therapy. Their BNP level before weaning decreased between the two attempts (517 vs 226 pg/ml, p=0.01). In survivors, BNP level was significantly correlated to weaning duration (rho=0.52, p<0.01).

CONCLUSIONS

Baseline plasma BNP level before the first weaning attempt is higher in patients with subsequent weaning failure and correlates to weaning duration.

Issues in weaning from mechanical ventilation: literature review

AIM

The aim of this paper is to raise questions on the effect of skill mix and organizational structure on weaning from mechanical ventilation.

BACKGROUND

Mechanical ventilation is an essential life-saving technology. There are, however, numerous associated complications that influence the morbidity and mortality of patients receiving intensive care. Therefore, it was essential to use the safest and most effective form of ventilation for the shortest possible duration. Because of the potential complications and costs of mechanical ventilation, research to date have focused on accurate weaning readiness assessment, methods and organizational aspects that influence the weaning process.

METHOD

In early 2005, the literature was reviewed from 1986 to 2004 by accessing the following databases: Medline, Proquest, Science Direct, CINAHL, and Blackwell Science. The keywords mechanical ventilation, weaning, protocols, critical care, nursing role, decision-making and weaning readiness were used separately and combinations.

DISCUSSION

Controversy exists in weaning practices about appropriate and efficacious weaning readiness assessment indicators, the best method of weaning and the use of weaning protocols. Arguably, the implementation of weaning protocols may have little effect in an environment that favours collaboration between nursing and medical staff, autonomous nursing decision-making in relation to weaning practices, and high numbers of nurses qualified at postgraduate level.

CONCLUSION

Further research is required that better quantifies critical care nurses' role in weaning practices and the contextual issues that influence both the nursing role and the process of weaning from mechanical ventilation.

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.

Weaning From Mechanical Ventilation: A Retrospective Analysis Leading to a Multimodal Perspective

Practitioners' decision for mechanical aid discontinuation is a challenging task that involves a complete knowledge of a great number of clinical parameters, as well as its evolution in time. Recently, an increasing interest on respiratory pattern variability as an extubation readiness indicator has appeared. Reliable assessment of this variability involves a set of signal processing and pattern recognition techniques. This paper presents a suitability analysis of different methods used for breathing pattern complexity assessment. The contribution of this analysis is threefold: 1) to serve as a review of the state of the art on the so-called weaning problem from a signal processing point of view; 2) to provide insight into the applied processing techniques and how they fit into the problem; 3) to propose additional methods and further processing in order to improve breathing pattern regularity assessment and weaning readiness decision. Results on experimental data show that sample entropy outperforms other complexity assessment methods and that multidimensional classification does improve weaning prediction. However, the obtained performance may be objectionable for real clinical practice, a fact that paves the way for a multimodal signal processing framework, including additional high-quality signals and more reliable statistical methods.

Predictors of extubation failure in patients with chronic obstructive pulmonary disease

Few studies have focused on extubation outcome in patients with chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation (MV). We conducted a study using prospectively collected data in a cohort of patients with COPD requiring invasive MV to identify variables associated with extubation failure. Use of noninvasive or invasive MV within 48 hours after extubation was defined as extubation failure. A total of 148 patients with COPD were studied. Extubation failure occurred in 35% of studied patients. Using multiple regression analysis, independent predictors of extubation failure were physiologic abnormalities measured by Simplified Acute Physiology Score II above 35 on intensive care unit (ICU) admission (odds ratio [OR], 3.88; 95% confidence interval [CI], 1.65-9.12), home noninvasive MV (OR, 12.99; 95% CI, 2.86-58.89), and sterile endotracheal aspirations on the day of extubation were predictors of success (OR, 0.23; 95% CI, 0.10-0.52). Despite high rate of extubation failure, survival to ICU discharge was 91% of the studied population. Extubation failure in patients with COPD remains high despite a successful spontaneous breathing on T piece. Simplified Acute Physiology Score II at ICU admission, home noninvasive MV, and isolated pathogens on quantitative cultures of tracheobronchial secretions within 72 hours preceding extubation were predictors of extubation failure in the study population.

The delivery of critical care services in US trauma centers: is the standard being met?

BACKGROUND

Although there is substantial evidence supporting the benefits of an intensivist model of critical care delivery, the extent to which this model has been adopted by trauma centers across the United States is unknown. We set out to evaluate how critical care is delivered in Level I and II trauma centers and the extent to which these centers implement evidence-based patient care practices known to improve outcome.

METHODS

All Level I and Level II trauma centers in the United States were surveyed using a previously validated questionnaire pertaining to the organizational characteristics of critical care units. Questions identifying the impediments to the implementation of an intensivist model of critical care delivery were added to the original survey. An intensivist model intensive care unit (ICU) was defined as one meeting all of the following criteria: a) the physician director was board certified in critical care; b) >50% of physicians responsible for care were board certified in critical care; c) an intensivist made daily rounds on the patients; and d) an intensive care team had the authority to write orders on the patients. The survey respondents were also queried regarding the extent to which they complied with evidence-based guidelines for care in the ICU.

RESULTS

The overall response rate was 65% (295 centers). Only 61% of Level I centers and 22% of Level II centers provided an intensivist model of critical care delivery. Sixty-nine percent of centers had a form of collaborative care with an intensivist, but few centers had dedicated intensivists without responsibilities outside the ICU. The most common reason cited for not involving an intensivist in the delivery of critical care services was a concern regarding a loss of continuity of care. There was limited implementation of evidence-based practices in the ICU; the model of critical care delivery had no effect on rates of implementation of these practices.

CONCLUSION

The process of trauma center verification and designation should assure a high quality of trauma care. In keeping with these expectations of quality, the delivery of critical care services in trauma centers should evolve to a model that both includes the trauma surgeon in the care of the injured and allows for collaboration with a dedicated intensivist, who may or may not be a surgeon. The benefits of an intensivist model might be distinct from the utilization of evidence-based practices, suggesting that there might be incremental benefit in using these practices as markers of quality.

Weaning smokers from mechanical ventilation

Because smoking causes oxidant stress, inflammation, and protease-antiprotease imbalance of the lung tissue, smokers may have a lower threshold for initiation of mechanical ventilation. Critical care team members should realize that not only the pulmonary system is compromised but also other protective response mechanisms of the body. Therefore, the role of every critical care team member is pivotal to ensure a successful weaning and extubation process for smokers. This article addresses how to best do that with a collaborative and evidence-based approach.

Improving Adherence to a Mechanical Ventilation Weaning Protocol for Critically Ill Adults: Outcomes After an Implementation Program

• Background Despite multiple reminders, education sessions, and multidisciplinary team involvement, adherence to an evidence-based mechanical ventilation weaning protocol had been less than 1% in a general systems intensive care unit since implementation.

• Objective To assess the effectiveness of using an implementation program, the Model for Accelerating Improvement, to improve adherence and clinical outcomes after restarting a mechanical ventilation weaning protocol in an adult general systems intensive care unit.

• Methods A prospective comparative design, before and after implementation of the Model for Accelerating Improvement, was used with a consecutive sample of 129 patients and 112 multidisciplinary team members. Clinical outcomes were rate of unsuccessful extubations, rate of ventilator-associated pneumonia, and duration of mechanical ventilation; practice outcomes were staff’s understanding of the mechanical ventilation weaning protocol, perceptions of the practice safety climate, and adherence to the weaning protocol.

• Results After the intervention, the rate of unsuccessful extubations decreased, and staff’s understanding of and adherence to the weaning protocol increased significantly. The rate of ventilator-associated pneumonia, duration of mechanical ventilation, and staff’s perceptions of the practice safety climate did not change significantly.

• Conclusion Implementing the Model for Accelerating Improvement improved understanding of and adherence to protocol-directed weaning and reduced the rate of unsuccessful extubations.

Sedative and Analgesic Medications: Risk Factors for Delirium and Sleep Disturbances in the Critically Ill

Sedatives and analgesics are routinely used in critically ill patients, although they have the potential for side effects, such as delirium and sleep architecture disruption. Although it should be emphasized that these medications are extremely important in providing patient comfort, health care professionals must also strive to achieve the right balance of sedative and analgesic administration through greater focus on reducing unnecessary or overzealous use. Ongoing clinical trials should help us to understand whether altering the delivery strategy, via daily sedation interruption, or protocolized target-based sedation or changing sedation paradigms to target different central nervous system receptors can affect cognitive outcomes and sleep preservation in our critically ill patients.

Extubation outcome following a spontaneous breathing trial with automatic tube compensation versus continuous positive airway pressure

OBJECTIVE

We hypothesized that the additional use of automatic tube compensation (ATC) during a spontaneous breathing trial with continuous positive airway pressure (CPAP), by minimizing respiratory work, would result in more patients undergoing successful extubation.

DESIGN

Prospective, randomized, controlled study.

SETTING

A ten-bed, general intensive care department at a tertiary-care hospital.

PATIENTS

Adult patients (n=99) who had undergone mechanical ventilation for >24 hrs and met defined criteria for a weaning trial.

INTERVENTIONS

Patients were randomized to undergo a 1-hr spontaneous breathing trial with either ATC with CPAP (ATC group, n=51) or CPAP alone (CPAP group, n=48). ATC was provided by commercially available mechanical ventilators. Patients tolerating the spontaneous breathing trial underwent immediate extubation. The primary outcome measure was successful extubation, defined as the ability to maintain spontaneous breathing for 48 hrs after discontinuation of mechanical ventilation and extubation.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in demographic, respiratory, or hemodynamic characteristics between the two groups at the start of the spontaneous breathing trial. There was a trend for more patients in the ATC group to tolerate the breathing trial and undergo extubation (96% vs. 85%; p=.08). The rate of reintubation was 14% in the ATC group and 24% in the CPAP group (p=.28). Significantly more patients in the ATC group thus met the criteria for successful extubation (82% vs. 65%; p=0.04).

CONCLUSION

This is the largest single-center study to date assessing the use of commercially available ATC and suggests that this might be a useful mode for performing a spontaneous breathing trial preceding extubation in a general intensive care population.

Successful treatment of patients with respiratory failure due to fungal infection after allogeneic hematopoietic stem cell transplantation

The mortality rate associated with respiratory failure due to invasive fungal infections after allogeneic hematopoietic stem cell transplantation (HSCT) is exceedingly high. We present a retrospective analysis of 4 HSCT recipients who survived long-term artificial respiration subsequent to pulmonary mycosis, and compare our current findings with historic data. Several clinical parameters indicate a remarkable improvement in the clinical courses of those patients in recent years: weaning time, extubation rate, and improvement of additional organ failures were all significantly better in patients treated after the emergence of new antimycotic agents, resulting in prolonged overall survival. We propose that our observations reflect an improved management of these patients, mainly because of the use of new antimycotics with alternative mechanisms of action and decreased toxicity, allowing for earlier, more aggressive, and more effective antifungal treatment approaches. In addition, the optimized use of new technologies designed to augment spontaneous breathing efforts by patients, mechanical ventilation, as well as the advantages of early tracheotomy will contribute to better outcomes in the treatment of respiratory failure due to pulmonary mycoses following allogeneic HSCT.

Management of patients requiring prolonged mechanical ventilation: report of a NAMDRC consensus conference

Patients requiring prolonged mechanical ventilation (PMV) are rapidly increasing in number, as improved ICU care has resulted in many patients surviving acute respiratory failure only to then require prolonged mechanical ventilatory assistance during convalescence. This patient population has clearly different needs and resource consumption patterns than patients in acute ICUs, and specialized venues, management strategies, and reimbursement schemes for them are rapidly emerging. To address these issues in a comprehensive way, a conference on the epidemiology, care, and overall management of patients requiring PMV was held. The goal was to not only review existing practices but to also develop recommendations on a variety of assessment, management, and reimbursement issues associated with patients requiring PMV. Formal presentations were made on a variety of topics, and writing groups were formed to address three specific areas: epidemiology and outcomes, management and care settings, and reimbursement. Each group was charged with summarizing current data and practice along with formulation of recommendations. A working draft of the products of these three groups was then created and circulated among all participants. The document was reworked with input from all concerned until a final product with consensus recommendations on 12 specific issues was achieved.

Determinants of time-to-weaning in a specialized respiratory care unit

BACKGROUND

As the decision-making process in long-term respiratory care units often depends on time-based outcomes, we sought to identify independent predictors of time-to-weaning (TTW) in a hospital-based specialized respiratory care unit.

METHODS

Characteristics that were identified in previous studies as predictors of weaning success in ICUs and long-term ventilator units were prospectively collected on 113 consecutive admissions to our unit. TTW analyses were performed with Kaplan-Meier curves, log rank test, and Cox proportional regression.

RESULTS

The TTW was shorter in patients with static lung compliance (Cst) of > 20 mL/cm H(2)O, a normal creatinine level (0.6 to 1.4 mg/dL), a rapid shallow breathing index (RSBI) of < or = 105, intact skin, and in those patients from a surgical referral source. We found an interaction between RSBI and Cst (p = 0.02) such that patients with an RSBI of < or = 105, regardless of Cst, had a median TTW of 11 days, those with an RSBI of > 105 and a Cst of > 20 had a median TTW of 31 days, and those with an RSBI of > 105 and a Cst of < or = 20 mL/cm H(2)O had not reached a median TTW by 60 days (p = 0.007 [log rank for linear trend]). In a Cox-proportional hazard model, both this categorization model of RSBI and Cst, and renal function had a significant impact on TTW.

CONCLUSIONS

In a multivariate model incorporating the variables reviewed, only the lung parameters (RSBI combined with Cst) and renal function remained independently associated with TTW.

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.