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

Does taking endurance into account improve the prediction of weaning outcome in mechanically ventilated children?

INTRODUCTION

We conducted the present study to determine whether a combination of the mechanical ventilation weaning predictors proposed by the collective Task Force of the American College of Chest Physicians (TF) and weaning endurance indices enhance prediction of weaning success.

METHOD

Conducted in a tertiary paediatric intensive care unit at a university hospital, this prospective study included 54 children receiving mechanical ventilation (> or = 6 hours) who underwent 57 episodes of weaning. We calculated the indices proposed by the TF (spontaneous respiratory rate, paediatric rapid shallow breathing, rapid shallow breathing occlusion pressure [ROP] and maximal inspiratory pressure during an occlusion test [Pimax]) and weaning endurance indices (pressure-time index, tension-time index obtained from P(0.1) [TTI1] and from airway pressure [TTI2]) during spontaneous breathing. Performances of each TF index and combinations of them were calculated, and the best single index and combination were identified. Weaning endurance parameters (TTI1 and TTI2) were calculated and the best index was determined using a logistic regression model. Regression coefficients were estimated using the maximum likelihood ratio (LR) method. Hosmer-Lemeshow test was used to estimate goodness-of-fit of the model. An equation was constructed to predict weaning success. Finally, we calculated the performances of combinations of best TF indices and best endurance index.

RESULTS

The best single TF index was ROP, the best TF combination was represented by the expression (0.66 x ROP) + (0.34 x Pimax), and the best endurance index was the TTI2, although their performance was poor. The best model resulting from the combination of these indices was defined by the following expression: (0.6 x ROP) - (0.1 x Pimax) + (0.5 x TTI2). This integrated index was a good weaning predictor (P < 0.01), with a LR+ of 6.4 and LR+/LR- ratio of 12.5. However, at a threshold value < 1.3 it was only predictive of weaning success (LR- = 0.5).

CONCLUSION

The proposed combined index, incorporating endurance, was of modest value in predicting weaning outcome. This is the first report of the value of endurance parameters in predicting weaning success in children. Currently, clinical judgement associated with spontaneous breathing trials apparently remain superior.

Impact of tracheotomy on sedative administration, sedation level, and comfort of mechanically ventilated intensive care unit patients*

OBJECTIVE

To assess the impact of tracheotomy on sedative administration, sedation level, and autonomy of mechanically-ventilated intensive care unit (ICU) patients.

DESIGN, SETTING, AND PATIENTS

In this observational study, the charts of all consecutive patients undergoing mechanical ventilation requiring tracheotomy over a 14-month period in our 18-bed tertiary care ICU were reviewed retrospectively. Patients' sedation levels (according to the Riker's 7-level sedation-agitation score) and intravenous (fentanyl and midazolam) and oral (clorazepate and haloperidol) sedative administration were measured daily during the 7 days before and after tracheotomy. We also recorded patients for whom chair positioning and oral alimentation became possible in the days following tracheotomy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Tracheotomy was performed on 72 (23.1%) of the 312 patients undergoing mechanical ventilation for > or = 48 hrs. After tracheotomy, median (25th, 75th percentiles) fentanyl and midazolam administration decreased from 866 (191, 1672) to 71 (3, 426) microg/(patient.day) and from 44 (16, 128) to 7 (1, 42) mg/(patient.day) (p < .001), respectively. Concomitant median time spent heavily sedated decreased from 7 (3, 17) to 1 (0, 6) hrs/day (p < .001), with no increase in agitation time. During the 7 days following tracheotomy, partial oral alimentation became possible for 35 patients (48.6%) and out-of-bed positioning became possible for 16 patients (22.2%).

CONCLUSION

On the basis of these observations, we conclude that tracheotomized mechanically ventilated ICU patients required less intravenous sedative administration, spent less time heavily sedated, and achieved more autonomy earlier.

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.

Fluid balance and weaning outcomes

OBJECTIVE

To examine the relationship of fluid balance and weaning outcomes.

METHODS

We prospectively collected demographic, physiological, daily fluid balance (measured inputs minus outputs), and weaning data from 87 mechanically ventilated patients.

PATIENTS

We examined 87 patients, a median age of 66 years, APACHE II of 22, and performed 205 breathing trials (BT); 38 patients (44%) were successfully extubated after their first BT with minimal or no pressure support.

RESULTS

Positive fluid balance (inputs>outputs) in the 24, 48, and 72 h and cumulatively (from hospital admission) prior to weaning were significantly greater in weaning failures than successes. Both univariate and multivariate analyses, adjusted for duration of mechanical ventilation and presence of chronic obstructive pulmonary disease, showed negative cumulative fluid balance 24 h prior to BTs (OR=2.9) and cumulative fluid balance (OR=3.4) to be independently associated with first-day weaning success. Similar relationships were demonstrated when all weaning attempts were analyzed. Negative fluid balance was as predictive of weaning outcomes as f/V(t) (likelihood of success was 1.7 for patients with negative fluid balance 24 h prior to weaning and 1.2 for those with f/Vt<100 min-1 l-1). Although administration of diuretics was associated with more negative fluid balance, it was not independently associated with weaning outcomes.

CONCLUSIONS

These data suggest that fluid balance, a potentially modifiable factor, is associated with weaning outcomes. A randomized study is required to determine whether diuresis to treat positive fluid balance expedites liberation from mechanical ventilation.

Early physiotherapy in the respiratory intensive care unit

Physiotherapy is an integral part of the management of patients in respiratory intensive care units (RICUs). The most important aim in this area is to enhance the overall patient's functional capacity and to restore his/her respiratory and physical independence, thus decreasing the risks of bed rest associated complications. This article is a review of evidence-based effectiveness of weaning practices and physiotherapy treatment for patients with respiratory insufficiency in a RICU. Literature searches were performed using general and specialty databases with appropriate keywords. The evidence for applying a weaning process and physiotherapy techniques in these patients has been described according to their individual rationale and efficacy. The growing number of patients treated in RICUs all over the world makes this non pharmacological approach both welcome and interesting. However, to date, there are only strong recommendations concerning the evidence-based strategies to speed weaning. Early physiotherapy may be effective in ICU: however, most techniques (postures, limb exercise and percussion/vibration in particular) need to be further studied in a large population. Evidence supporting physiotherapy intervention is limited as there are no studies examining the specific effects of interventions on long-term outcome.

[Management of acute pulmonary failure: diagnostics-ventilation-withdrawal]

Acute pulmonary failure by definition excludes cardiac insufficiency as the pathogenetic mechanism involved in the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The systemic inflammatory reaction underlying acute pulmonary failure has many etiological causes. One of the most important trigger mechanisms is sepsis. In the realm of cardiac intensive care medicine, the systemic inflammatory reaction is observed in conjunction with assist systems, during extracorporeal circulation, or in the course of cardiogenic shock. In the end, even mechanical ventilation itself can elicit an inflammatory reaction and result in pulmonary failure through ventilator-associated lung injury. Knowledge of the mechanisms has led to the concept of protective ventilation, which exerts both prophylactic and therapeutic effects. Protective ventilation is an integral part of a bundle of therapeutic intensive care measures. Both constitute the essence of management of acute pulmonary failure.

Recent advances in mechanical ventilation

Important advances have been made over the past decade towards understanding the optimal approach to ventilating patients with acute respiratory failure. Evidence now supports the use of noninvasive positive pressure ventilation in selected patients with hypercapnic respiratory failure and chronic obstructive pulmonary disease, cardiogenic pulmonary edema, and for facilitating the discontinuation of ventilatory support in patients with chronic pulmonary disease. The concept of a lung protective ventilatory strategy has revolutionized the management of the acute respiratory distress syndrome. The process of liberation from mechanical ventilation is becoming more standardized, with evidence supporting daily trials of spontaneous breathing in all suitable mechanically ventilated patients. This article critically reviews the most important recent advances in mechanical ventilation and suggests future directions for further research in the field.

Modern management of respiratory failure due to pulmonary mycoses following allogeneic hematopoietic stem-cell transplantation

Pulmonary mycoses count among the most dangerous complications in allogeneic hematopoietic stem cell transplantation. Despite the establishment of antifungal chemoprophylaxis and empirical antifungal treatment, they frequently lead to respiratory failure and are still associated with an extraordinarily poor prognosis. However, the emergence of new antimycotics with alternative mechanisms of actions and decreased toxicity in combination with the development of new non culture-based diagnostic techniques may allow 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 tracheostomy lead us to expect better outcomes in the treatment of respiratory failure due to pulmonary mycoses following allogeneic hematopoietic stem cell transplantation.

Clinical review: respiratory mechanics in spontaneous and assisted ventilation

Pulmonary disease changes the physiology of the lungs, which manifests as changes in respiratory mechanics. Therefore, measurement of respiratory mechanics allows a clinician to monitor closely the course of pulmonary disease. Here we review the principles of respiratory mechanics and their clinical applications. These principles include compliance, elastance, resistance, impedance, flow, and work of breathing. We discuss these principles in normal conditions and in disease states. As the severity of pulmonary disease increases, mechanical ventilation can become necessary. We discuss the use of pressure–volume curves in assisting with poorly compliant lungs while on mechanical ventilation. In addition, we discuss physiologic parameters that assist with ventilator weaning as the disease process abates.

Risk factors for extubation failure in mechanically ventilated pediatric patients

OBJECTIVE

To describe the incidence of extubation failure and its associated risk factors among mechanically ventilated children.

METHOD

Prospective cohort study. Children who were mechanically ventilated for longer than 12 hrs were followed up to 48 hrs after extubation. Cases of upper airway obstruction, accidental extubation, tracheostomy, or death before extubation were excluded. Extubation failure was defined as reintubation within 48 hrs after extubation. Student's t -test, Mann-Whitney, and chi-squared tests, odds ratio with 95% confidence interval, and multivariate analysis were used for data analysis.

RESULTS

Extubation failure rate was 10.5% (13 of 124 patients). Variables associated with extubation failure were age between 1 and 3 mos (odds ratio [OR] = 5.68; 95% confidence interval [CI] = 1.58-20.42), mechanical ventilation >15 days (OR = 6.36; 95% CI = 1.32-30.61), mean oxygenation index (OI) >5 (OR = 4.08; 95% CI = 1.25-13.30), mean airway pressure 24 hrs before extubation lower than 5 cm H(2)O (OR = 6.03; 95% CI = 1.48-24.60), continuous positive airway pressure (CPAP) (OR = 4.71; 95% CI = 1.34-16.58), dopamine and dobutamine use (OR = 3.71; 95% CI = 1.08-12.78), intravenous sedation >10 days (OR = 6.60; 95% CI = 1.62-26.90), tachypnea and subcostal retractions (relative risk [RR] = 3.68; 95% CI = 1.14-11.93), and inspired fraction of oxygen (Fio(2)) > 0.4 after extubation (RR = 3.63; 95% CI = 1.21-10.88). After multiple logistic regression analysis, age between 1 and 3 mos, mean OI > 5, CPAP and mechanical ventilation >15 days remained associated with extubation failure.

CONCLUSION

Extubation failure was more frequent among young infants who received prolonged ventilatory support and intravenous sedation, used CPAP, had impaired lung oxygenation, and required inotropic therapy.

Erythropoietin response in critically ill mechanically ventilated patients: a prospective observational study

Introduction

Anemia is a common problem in critically ill patients. The etiology of anemia of critical illness is often determined to be multifactorial in the clinical setting, but the pathophysiology remains to be elucidated. Erythropoietin (EPO) is an endogenous glycoprotein hormone that serves as the primary stimulus for erythropoiesis. Recent evidence has demonstrated a blunted EPO response as a factor contributing to anemia of critical illness in specific subsets of patients. Critically ill patients requiring mechanical ventilation who exhibit anemia have not been the subject of previous studies. Our goal was to evaluate the erythropoietic response to anemia in the critically ill mechanically ventilated patient.

Methods

A prospective observational study was undertaken in the medical intensive care unit of a tertiary care, military hospital. Twenty patients admitted to the medical intensive care unit requiring mechanical ventilation for at least 72 hours were enrolled as study patients. EPO levels and complete blood count were measured 72 hours after admission and initiation of mechanical ventilation. Admission clinical and demographic data were recorded, and patients were followed for the duration of mechanical ventilation. Twenty patients diagnosed with iron deficiency anemia in the outpatient setting were enrolled as a control population. Control patients had baseline complete blood count and iron panel recorded by primary care physicians. EPO levels were measured at the time of enrollment in conjunction with complete blood count.

Results

The mean EPO level for the control population was 60.9 mU/ml. The mean EPO level in the mechanically ventilated patient group was 28.7 mU/ml, which was significantly less than in the control group (P = 0.035). The mean hemoglobin value was not significantly different between groups (10.6 g/dl in mechanically ventilated patients versus 10.2 g/dl in control patients; P > 0.05).

Conclusion

Mechanically ventilated patients demonstrate a blunted EPO response to anemia. Further study of therapies directed at treating anemia of critical illness and evaluating its potential impact on mechanical ventilation outcomes and mortality is warranted.

Protocol-directed weaning: a process of continuous performance improvement

The use of a nursing-directed and/or respiratory therapist-directed protocol in many intensive care units for weaning from mechanical ventilation is associated with a shorter duration of ventilation and length of stay in the ICU. Most protocols have two formal components: the daily screening of a set of simple observations or interventions to identify readiness to proceed, followed by a spontaneous breathing trial that tests the patient's ability to breathe independently. The daily screen is designed to identify potential barriers regarding medical stability, level of consciousness, oxygenation, ventilation, and airway patency and protection. However, one must avoid selecting criteria that are too restrictive, potentially delaying the discontinuation of ventilation.

Impact of a nurses' protocol-directed weaning procedure on outcomes in patients undergoing mechanical ventilation for longer than 48 hours: a prospective cohort study with a matched historical control group

INTRODUCTION

The aim of the study was to determine whether the use of a nurses' protocol-directed weaning procedure, based on the French intensive care society (SRLF) consensus recommendations, was associated with reductions in the duration of mechanical ventilation and intensive care unit (ICU) length of stay in patients requiring more than 48 hours of mechanical ventilation.

METHODS

This prospective study was conducted in a university hospital ICU from January 2002 through to February 2003. A total of 104 patients who had been ventilated for more than 48 hours and were weaned from mechanical ventilation using a nurses' protocol-directed procedure (cases) were compared with a 1:1 matched historical control group who underwent conventional physician-directed weaning (between 1999 and 2001). Duration of ventilation and length of ICU stay, rate of unsuccessful extubation and rate of ventilator-associated pneumonia were compared between cases and controls.

RESULTS

The duration of mechanical ventilation (16.6 +/- 13 days versus 22.5 +/- 21 days; P = 0.02) and ICU length of stay (21.6 +/- 14.3 days versus 27.6 +/- 21.7 days; P = 0.02) were lower among patients who underwent the nurses' protocol-directed weaning than among control individuals. Ventilator-associated pneumonia, ventilator discontinuation failure rates and ICU mortality were similar between the two groups.

DISCUSSION

Application of the nurses' protocol-directed weaning procedure described here is safe and promotes significant outcome benefits in patients who require more than 48 hours of mechanical ventilation.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Assessment of the Mechanically Ventilated Patient

Multiple perspectives must be considered when assessing the mechanically ventilated patient. Assessment begins before the advance practice nurse (APN) encounters the patient. Important information about the patient can be gleaned from the history, medications, and social history. The APN then observes the patient to determine if patient-ventilator synchrony has been achieved. Physical findings are gathered and correlated with the chest radiogram. Data from the ventilator are evaluated to assess compliance, minute ventilation, tidal volume, and other parameters that will assist in the evaluation of the patient's needs. Electrolytes, acid-base state, and nutrition must all be considered to obtain a complete assessment of these patients. From all these data points, the APN can develop a detailed plan of care that will enhance positive patient outcomes.

The science of weaning: when and how?

Weaning patients from long-term mechanical ventilation continues to be a goal of clinicians and scientists and the hospitals charged with their care. This article describes the science of the "wean" and the "how" of weaning. A goal of scientists has been to develop predictors that determine accurately the optimal time to initiate weaning. Unfortunately to date none has emerged as superior. Quite simply, predictors do not predict. In contrast, methods that decrease variation in care practices have demonstrated positive outcomes. The methods include protocols for weaning trials and sedation and other system initiatives inclusive of a multidisciplinary plan of care or clinical pathway.

Mechanical Ventilation

Mechanical ventilation is the second most frequently performed therapeutic intervention after treatment for cardiac arrhythmias in intensive care units today. Countless lives have been saved with its use despite being associated with a greater than 30% in-hospital mortality rate. As life expectancies increase and people with chronic illnesses survive longer, artificial support with mechanical ventilation is also expected to rise. In one survey, over half of senior internal medicine residents reported their training on mechanical ventilation as inadequate, whereas the majority of critical care nurses reported having received no formal education on its use. Technological advances resulting in the availability of sleeker ventilators with graphic waveform displays and new modes of ventilation have challenged the bedside clinicians to incorporate this new data along with evidenced-based research into their daily practice. A review of current thoughts on mechanical ventilation and weaning is presented.

Noninvasive positive-pressure ventilation for respiratory failure after extubation

BACKGROUND

The need for reintubation after extubation and discontinuation of mechanical ventilation is not uncommon and is associated with increased mortality. Noninvasive positive-pressure ventilation has been suggested as a promising therapy for patients with respiratory failure after extubation, but a single-center, randomized trial recently found no benefit. We conducted a multicenter, randomized trial to evaluate the effect of noninvasive positive-pressure ventilation on mortality in this clinical setting.

METHODS

Patients in 37 centers in eight countries who were electively extubated after at least 48 hours of mechanical ventilation and who had respiratory failure within the subsequent 48 hours were randomly assigned to either noninvasive positive-pressure ventilation by face mask or standard medical therapy.

RESULTS

A total of 221 patients with similar baseline characteristics had been randomly assigned to either noninvasive ventilation (114 patients) or standard medical therapy (107 patients) when the trial was stopped early, after an interim analysis. There was no difference between the noninvasive-ventilation group and the standard-therapy group in the need for reintubation (rate of reintubation, 48 percent in both groups; relative risk in the noninvasive-ventilation group, 0.99; 95 percent confidence interval, 0.76 to 1.30). The rate of death in the intensive care unit was higher in the noninvasive-ventilation group than in the standard-therapy group (25 percent vs. 14 percent; relative risk, 1.78; 95 percent confidence interval, 1.03 to 3.20; P=0.048), and the median time from respiratory failure to reintubation was longer in the noninvasive-ventilation group (12 hours vs. 2 hours 30 minutes, P=0.02).

CONCLUSIONS

Noninvasive positive-pressure ventilation does not prevent the need for reintubation or reduce mortality in unselected patients who have respiratory failure after extubation.

Pro/con clinical debate: tracheostomy is ideal for withdrawal of mechanical ventilation in severe neurological impairment

Most clinical trials on the topic of extubation have involved patients outside the neurological intensive care unit. As a result, in this area clinicians are left with little evidence on which to base their decision making. Although tracheostomies are increasingly common procedures, they are not without complications and costs, and hence a decision to perform them should not be taken lightly. In this issue of Critical Care two groups debate the merits of tracheostomy before extubation in a patient with neurological impairment. What becomes very clear is the need for more high quality data for this common clinical problem.

A prospective, blinded evaluation of indexes proposed to predict weaning from mechanical ventilation

OBJECTIVE

To conduct a blinded evaluation of the predictors of weaning from mechanical ventilation.

DESIGN

A prospective clinical study.

SETTING

A 23-bed general intensive care unit.

PATIENTS

Ninety-three non-selected patients, ventilated for more than 48 h.

METHODS

The study had two steps: at first, patients' data were used to select the cut-off value for weaning predictors (the minimal false classification). The cut-off value for each index was prospectively assessed in a group of 52 patients. The predictive performance of these indexes was evaluated by calculating the area under the receiver operating characteristic curve. In the prospective-validation set we used Bayes' theorem to assess the probability of each test in predicting weaning. The physicians making decisions about the weaning process were always unaware of the predictive values. Weaning was considered successful if spontaneous breathing was sustained for more than 48 h after extubation.

MEASUREMENTS AND RESULTS

During the first 2 min after discontinuation of mechanical ventilation the following tests were performed: vital capacity, tidal volume, airway occlusion pressure (P(0.1)), minute ventilation, respiratory rate, maximal inspiratory pressure (MIP), respiratory frequency to tidal volume (f/V(T)), P(0.1)/MIP and P(0.1) x f/V(T). The areas under the curve showed that the tests had not the ability to distinguish between successful and unsuccessful weaning.

CONCLUSION

Our results show that all the evaluated indexes are poor predictors of weaning outcome in a general intensive care unit population.

Neurologic status, cough, secretions and extubation outcomes

OBJECTIVE

To determine the degree to which neurologic function, cough peak flows and quantity of endotracheal secretions affected the extubation outcomes of patients who had passed a trial of spontaneous breathing (SBT).

DESIGN

Prospective observational study.

SETTING

The medical intensive care unit of a 325-bed teaching hospital.

MEASUREMENTS AND MAIN RESULTS

Cough peak flow (CPF), endotracheal secretions and ability to complete four simple tasks were measured just before extubation in patients who had passed a SBT. Eighty-eight patients were studied; 14 failed their first trials of extubation. The CPF of patients who failed was lower than that of those who had a successful extubation (58.1+/-4.6 l/min vs 79.7+/-4.1 l/min, p=0.03) and those with CPF 60 l/min or less were nearly five times as likely to fail extubation compared to those with CPF higher than 60 l/min (risk ratio [RR]=4.8; 95% CI=1.4-16.2). Patients with secretions of more than 2.5 ml/h were three times as likely to fail (RR=3.0; 95% CI=1.0-8.8) as those with fewer secretions. Patients who were unable to complete four simple tasks (i.e. open eyes, follow with eyes, grasp hand, stick out tongue) were more than four times as likely to fail as those who completed the four commands (RR=4.3; 95% CI=1.8-10.4). There was synergistic interaction between these risk factors. The failure rate was 100% for patients with all three risk factors compared to 3% for those with no risk factors (RR=23.2; 95% CI=3.2-167.2). The presence of any two of the above risk factors had a sensitivity of 71 and specificity of 81% in predicting extubation failure. Patients who failed a trial of extubation were 3.8 times as likely to have any two risk factors compared to those who were successful.

CONCLUSIONS

These simple, reproducible methods may provide a clinically useful approach to guiding the extubation of patients who have passed a SBT.

Severe agitation among ventilated medical intensive care unit patients: frequency, characteristics and outcomes

OBJECTIVE

To determine the frequency, characteristics and outcomes of severe agitation among ventilated medical intensive care unit (MICU) patients.

DESIGN

Prospective cohort study.

SETTING

Eighteen-bed MICU in 964-bed tertiary care center.

PATIENTS

All ventilated patients, aged 18 years or older and admitted for more than 24 h between January 1, 2001 and May 8, 2001.

INTERVENTIONS

None.

MEASUREMENTS

Data were collected daily by concurrent chart abstractions. Variables included sociodemographic, clinical, laboratory, pharmacologic and non-pharmacologic interventions, ventilator settings and adverse events. Severe agitation, the main outcome variable, was defined as two or more Motor Activity Assessment Scale (MAAS) scores above 4 in a 24-h period and sedative and/or narcotic doses above the established sedation and analgesia protocol or a combination of two or more sedatives.

RESULTS

Twenty-three (16.1%) of 143 enrolled patients exhibited severe agitation. Agitated patients were younger (hazard ratio [HR] 1.32), more likely to be admitted from an outside hospital ICU (HR 2.48), had lower pH (HR 1.55) and PaO(2)/FIO(2) less than 200 mmHg (HR 2.59). Agitated patients had longer MICU stays (median 12 versus 5 days, p<0.0001) and more ventilator days (median 14 versus 6, p<0.0001). Agitated patients were more likely to self-extubate (26% versus 6%, p=0.002). Benzodiazepines, narcotics and neuromuscular blocking agents were administered more frequently and at higher doses, but haloperidol was not.

CONCLUSION

Severe agitation occurs commonly in critically ill patients and is associated with adverse events including longer ICU stays, duration of mechanical ventilation and self-extubation.

Biofeedback as a supportive method in weaning long-term ventilated critically ill patients

Weaning a patient from mechanical ventilation is occasionally a difficult process complicated by the patient's emotional state. Anxiety, agitation, depression and other emotional disturbances can start a vicious circle between fear of losing breath and dyspnea that impairs the process of withdrawing ventilatory support. A biocybernetic loop model is suggested that integrates psychological variables (e.g., capacity of self-control, self-confidence, sense of self-efficacy) as important factors for a successful weaning. The paradigm of biofeedback is regarded as a suited approach to strengthen these psychological factors. It means the externalization of physiological functions especially of those from the autonomous nervous system so that a patient becomes aware of them. In the case of the ventilated patient, it is assumed that the transformation of the respiratory activities into perceptible (acoustic and visual) signals supports the patient's self-controlling behaviour during the weaning process. He gets positive reinforcement for his efforts to influence his breathing intentionally and, by continuous and immediate information, he regains self-confidence to control his somatic functions effectively. The application of biofeedback is mainly described in single case studies. They all report a decrease in the respiratory rate and an increase in the tidal volume. The need for a controlled study is suggested that would answer the question of whether biofeedback is an appropriate psychological tool to facilitate the weaning process in mechanically ventilated patients.

Clinical outcomes for the elderly patient receiving a tracheotomy

BACKGROUND

Tracheotomies are routinely performed for severely ill and elderly patients with respiratory failure. This intervention is questioned, given the poor survival rate in this group. Outcomes analysis is performed after tracheotomy.

METHODS

This is a retrospective study of 78 elderly patients, who received tracheotomies for respiratory failure. Pretracheotomy data (age, length of oral intubation, and DNR status) were collected. Outcomes analyzed during the same admission as the tracheotomy included death versus discharge, ventilator dependence, vocal function, route of feeding, decannulation, and ICU discharge disposition.

RESULTS

The mean age was 77.6 +/- 11 years (median, 79 years) and patients were intubated for 16.7 +/- 9 days. Forty-two percent (n = 33) obtained DNR orders after tracheotomy, and 8% (n = 6) before tracheotomy. Seventy-one percent of patients (n = 55) had gastrostomy tubes placed. Fifty-six percent of patients (n = 44) died after tracheotomy; median time from tracheotomy to death was 31 days. After tracheotomy, 53 % (n = 41) remained at least partially ventilator dependent, 18 % (n = 14) regained consistent vocal function, and 13 % (n = 10) were decannulated. For those who died, 27 % (n = 12) died without leaving the ICU.

CONCLUSION

These data demonstrate that a large proportion of elderly, severely ill patients with respiratory failure suffer poor outcomes after tracheotomy. More stringent criteria are necessary for performing the tracheotomy in this patient population.

Long-term outcomes for patients discharged from a long-term hospital-based weaning unit

BACKGROUND

Because little attention has been given to the long-term outcomes of patients in hospital-based ventilator weaning units, we undertook this assessment of 5-year outcomes of patients discharged from the Respiratory Special Care Unit (ReSCU) of the Cleveland Clinic Hospital.

METHODS

The ReSCU consists of six private beds on a pulmonary specialty ward. Features of the unit include noninvasive monitoring with signal output at each bedside and at a central monitoring station. The unit is staffed by nurses with specific pulmonary rehabilitation expertise and has 24-h respiratory therapist supervision. Ongoing prospective data collection in the ReSCU includes monitoring weaning success, demographic features, hospital discharge status, and hospital discharge disposition. Long-term outcomes were ascertained using a review of hospital medical records and direct inquiry to patients and/or family members.

RESULTS

Between August 22, 1993, and August 22, 1996, 162 individuals were admitted to the ReSCU, with 7 persons having repeat admissions during separate hospital admissions. Seventeen percent of these persons (n = 27) died during the hospitalization, while 83% were discharged from the index hospitalization (ie, the hospital stay during which the patient was first admitted to the ReSCU). Kaplan-Meier (KM) mortality rate estimates were as follows: 1 month, 11% (95% confidence interval [CI], 6 to 15%); 1 year, 57% (95% CI, 49 to 65%); 2 years, 68% (95% CI, 61 to 75%); 3 years, 73% (95% CI, 66 to 80%); 4 years, 76% (95% CI, 69 to 83%); and 5 years, 81% (95% CI, 75 to 87%). The 5-year KM mortality rate estimates considered by year of ReSCU admission were as follows: 1993, 92% (95% CI, 77 to 100%); 1994, 84% (95% CI, 73 to 95%); 1995, 87% (95% CI, 77 to 96%); and through August 22, 1996, 66% (95% CI, 51 to 81%).

CONCLUSIONS

In this population requiring prolonged inpatient ventilatory support, moderately high acute mortality rates are consistent with data from other series. In this analysis of longer-term follow-up rates, the 5-year survival rates are low, with higher mortality rates within the first 2 years and a slower decline in survival thereafter.

Automatic “Respirator/Weaning” with Adaptive Support Ventilation: The Effect on Duration of Endotracheal Intubation and Patient Management

Adaptive support ventilation (ASV) provides an automatic adaptation of the ventilator settings to patient's passive and active respiratory mechanics. In a randomized controlled study, we evaluated automatic respiratory weaning in ASV for early tracheal extubation after cardiac surgery. Eligible patients were assigned to either an ASV protocol or a standard one consisting of synchronized intermittent ventilation followed by pressure support. Eighteen patients completed the ASV protocol, and 16 completed the standard one. There were no differences between groups in perioperative characteristics, lengths of tracheal intubation and intensive care unit stay, and ventilatory variables, except less peak inspiratory pressure during the initial phase in ASV (17.5 +/- 0.8 versus 22.2 +/- 0.8 cm H(2)O; P < 0.01). ASV patients required fewer ventilatory settings manipulations (2.4 +/- 0.7 versus 4.0 +/- 0.8 manipulations per patient; P < 0.05) and endured less high-inspiratory pressure alarms (0.7 +/- 2.4 versus 2.9 +/- 3.0; P < 0.05). These results suggest that in this specific population of patients, automation of postoperative ventilation with ASV resulted in an outcome similar to the control group. The internal logic of the new device resulted in less manipulation of the setting and alarms that could simplify respiratory management.

IMPLICATIONS

Adaptive support ventilation (ASV), a ventilatory mode providing automatic adjustment of the settings was compared with standard management for rapid tracheal extubation after cardiac surgery. The two approaches were equal in terms of outcome. In ASV, we observed fewer ventilator settings manipulations and a smaller amount of alarms, suggesting that this automatic mode may simplify postoperative respiratory management without delaying extubation.

Implementation of an institutional program to improve clinical and financial outcomes of mechanically ventilated patients: One-year outcomes and lessons learned*

OBJECTIVE

To determine the effect of an institutional approach to the care of patients requiring mechanical ventilation for longer than three consecutive days in five adult intensive care units (ICU) on clinical and financial outcomes.

DESIGN

A multidisciplinary team was selected from five adult ICUs to design the approach. Planning occurred from August 1999 to September 2000. The process was called outcomes management (OM) and included an evidence-based clinical pathway, protocols for weaning and sedation use, and the selection of four advanced practice nurses (called outcomes managers) to manage and monitor the program.

SETTING

The project was completed in a 550-bed mid-Atlantic academic medical center. The ICUs included the following: coronary care, medical ICU, neuroscience ICU, surgical trauma ICU, and thoracic cardiovascular ICU.

PATIENTS

The sample included 595 pre-OM patients and 510 post-OM patients mechanically ventilated for greater than three consecutive days.

INTERVENTIONS

Full implementation of the OM approach occurred in March 2001. Retrospective baseline (18 months pre-OM) and prospective (12 months OM) clinical and financial data were compared.

MEASUREMENTS AND MAIN RESULTS

Statistically significant differences in clinical outcomes were demonstrated in the managed patients compared with those managed before the institutional approach. Outcomes include ventilator duration (median days declined from ten to nine; p =.0001), ICU length of stay (median days declined from 15 to 12; p =.0008), hospital length of stay (median days declined from 22 to 20; p =.0001), and mortality rate (declined from 38% to 31%, p =.02). More than 3,000,000 US dollars cost savings were realized in the OM group.

CONCLUSIONS

This institutional approach to the care of patients ventilated >3 days improved all clinical and financial outcomes of interest. To date, few similar initiatives have demonstrated similar results. The approach and lessons learned in this process improvement project may be helpful to other institutions attempting to improve outcomes in this vulnerable population.

Extubation failure: diagnostic value of occlusion pressure (P0.1) and P0.1-derived parameters

OBJECTIVE

To evaluate the ability of the new, built-in occlusion pressure (P0.1) measurement to predict extubation failure.

DESIGN AND SETTING

Prospective observational multicentre study in the ICU of five general hospitals.

PATIENTS

Hundred thirty patients on mechanical ventilation longer than 48 h when considered ready for weaning.

MEASUREMENTS AND RESULTS

Patients underwent a 30-min spontaneous breathing trial with simultaneous monitoring of occlusion pressure (P0.1) and breathing pattern (f/Vt). Sixteen patients (12%) failed the weaning trial and full ventilatory support was resumed, while 114 tolerated the trial and were extubated. Twenty-one (18%) required reintubation within 48 h. The area under the ROC curve for diagnosing extubation failure was 0.53 for f/Vt, 0.59 for P0.1 and 0.61 for P0.1*f/Vt (p=NS). Accordingly, P0.1*f/Vt more than 100 detected extubation failure with a sensitivity of 0.89, specificity of 0.35, positive predictive value of 0.21 and negative predictive value of 0.94.

CONCLUSION

During a first trial of spontaneous breathing on pressure support ventilation (PSV), bedside P0.1 and P0.1*f/Vt are of little help, if any, for predicting extubation failure.

Clinical experience with adaptive support ventilation for fast-track cardiac surgery

OBJECTIVE

To evaluate adaptive support ventilation (ASV), an automatic microprocessor-controlled mode of mechanical ventilation, for the initial ventilatory management in consecutive patients eligible for early extubation after cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Nonuniversity cardiac center.

PARTICIPANTS

One hundred fifty-five consecutive patients eligible for early tracheal extubation after cardiac surgery.

INTERVENTIONS

On intensive care unit arrival, patients were ventilated by adaptive support ventilation. This mode provided an automatic selection of initial ventilatory parameters and a continuous adaptation to patient's respiratory activity, guaranteeing that a preset minute ventilation was delivered. Once the patients had recovered sustained spontaneous ventilation, the ventilator was switched manually to pressure support for the terminal part of respiratory weaning followed by extubation.

MEASUREMENTS AND MAIN RESULTS

In adaptive support ventilation, all patients could be ventilated satisfactorily except 1; tidal volume was 8.7 +/- 1.4 mL/kg of ideal body weight (mean +/- SD), plateau pressure was 20.3 +/- 3.9 cmH(2)O, and arterial blood gas measurements were satisfactory. One hundred thirty-four patients (86%) were extubated within 6 hours, and intubation time was 3.6 (2.53-4.83) hours (median, [quartiles]). No reintubation because of respiratory failure was required. Adaptive support ventilation was considered easy to use by both the nurses and physicians.

CONCLUSIONS

Adaptive support ventilation was used in a group of 155 consecutive patients after fast-track cardiac surgery. This ventilation mode was safe, easy to apply, and allowed rapid extubation in suitable patients. ASV may facilitate postoperative respiratory management.

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

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

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

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

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

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

Cough peak flows and extubation outcomes

BACKGROUND

Semiobjective methods of quantifying cough strength and endotracheal secretions have been demonstrated to predict extubation outcomes of patients who have passed a spontaneous breathing trial (SBT).

HYPOTHESIS

Cough strength, measured by voluntary cough peak expiratory flow (PEF), and endotracheal secretions, measured volumetrically, predict extubation outcomes of patients who have passed an SBT.

PATIENT POPULATION

Critically ill patients admitted to the medical ICU of a 300-bed community teaching hospital.

METHODS

All patients who passed an SBT and were about to be extubated were studied. The best of three cough attempts, measured with an in-line spirometer, and the average hourly rate of suctioned secretions prior to extubation were recorded with other weaning parameters and demographic data.

RESULTS

Ninety-five patients were studied before and after 115 extubations. There were 13 unsuccessful extubations. There were no differences in age, gender, duration of intubation, or APACHE (acute physiology and chronic health evaluation) II scores between successful and unsuccessful extubations. The magnitude of endotracheal secretions was not associated with outcomes. The PEF of patients with unsuccessful extubations was significantly lower than that of those with successful extubations (64.2 +/- 6.8 L/min vs 81.9 +/- 2.7 L/min, p = 0.03). Patients with unsuccessful extubations stayed longer in the ICU than those with successful extubations (11.7 +/- 2.1 days vs 5.3 +/- 0.4 days, p = 0.009). Those with PEF <or= 60 L/min were five times as likely to have unsuccessful extubations and were 19 times as likely to die on that hospital stay. PEF and the rapid shallow breathing index were independently associated with extubation outcomes, while only the PEF (<or= 60 L/min) was independently associated with in-hospital mortality.

CONCLUSION

These data suggest that cough strength, measured objectively, is a predictor of extubation outcome, morbidity, and mortality.

Treatment algorithms and protocolized care

PURPOSE OF REVIEW

Excess information in complex ICU environments exceeds human decision-making limits and likely contributes to unnecessary variation in clinical care, increasing the likelihood of clinical errors. I reviewed recent critical care clinical trials searching for information about the impact of protocol use on clinically pertinent outcomes.

RECENT FINDINGS

Several recently published clinical trials illustrate the importance of distinguishing efficacy and effectiveness trials. One of these trials illustrates the danger of conducting effectiveness trials before the efficacy of an intervention is established. The trials also illustrate the importance of distinguishing guidelines and inadequately explicit protocols from adequately explicit protocols. Only adequately explicit protocols contain enough detail to lead different clinicians to the same decision when faced with the same clinical scenario.

SUMMARY

Differences between guidelines and protocols are important. Guidelines lack detail and provide general guidance that requires clinicians to fill in many gaps. Computerized or paper-based protocols are detailed and, when used for complex clinical ICU problems, can generate patient-specific, evidence-based therapy instructions that can be carried out by different clinicians with almost no interclinician variability. Individualization of patient therapy can be preserved by these protocols when they are driven by individual patient data. Explicit decision-support tools (eg, guidelines and protocols) have favorable effects on clinician and patient outcomes and can reduce the variation in clinical practice. Guidelines and protocols that aid ICU decision makers should be more widely distributed.

Positive pressure mechanical ventilation

There have been numerous advances in the application of positive pressure mechanical ventilation in the last two decades. As knowledge of pulmonary physiology expands, the application of modes and parameters to maximize the efficacy and minimize the complications of ventilatory support continues to advance. As the use of noninvasive ventilation becomes more widespread, its usefulness in certain clinical entities such as COPD exacerbations and acute cardiogenic pulmonary edema will become more prominent. The role of specific modes and parameters of these devices likely will be further refined to maximize outcomes.

Subjective Perceptions and Physiological Variables During Weaning From Mechanical Ventilation

• Background As costs related to mechanical ventilation increase, clear indicators of patients’ readiness to be weaned are needed. Research has not yet yielded a consensus on physiological variables that are consistent correlates of weaning outcomes. Subjective perceptions rarely have been examined for their contribution to successful weaning.

• Objective To explore the subjective perceptions of dyspnea, fatigue, and self-efficacy and selected physiological variables in patients being weaned from mechanical ventilation.

• Methods Data were collected prospectively on 68 patients being weaned from mechanical ventilation. Subjective perceptions were measured by using 3 visual analog scales; physiological variables were measured by using the Burns Weaning Assessment Program and a patient profile. Weaning outcomes were recorded 24 hours after data collection.

• Results Participants were primarily white women and required mechanical ventilation for a mean of less than 4 days. Participants reported mild dyspnea, moderate fatigue, and high weaning self-efficacy. High Pao2, low Paco2, stable hemodynamic status, adequate cough and swallow reflexes, no metabolic changes, and no abdominal problems were associated with complete weaning (P = .05). Subjective perceptions were associated with physiological variables but not with weaning outcomes.

• Conclusions Multidimensional assessment of both primary and secondary indicators of readiness to be weaned is necessary for timely, efficient weaning from mechanical ventilation. Primary assessments include physiological variables related to gas exchange, hemodynamic status, diaphragmatic expansion, and airway clearance. Secondary assessments include perceptions related to key physiological variables. Additional research is needed to determine the predictive value of physiological variables and perceptions of dyspnea, fatigue, and self-efficacy.

Clinical management of stressors perceived by patients on mechanical ventilation

Psychological and psychosocial stressors perceived by the mechanically ventilated patient include intensive care unit environmental factors, communication factors, stressful symptoms, and the effectiveness of interventions. The studies reviewed in this article showed four stressors commonly identified by mechanically ventilated patients including dyspnea, anxiety, fear, and pain. Few interventional studies to reduce these stressors are available in the literature. Four interventions including hypnosis and relaxation, patient education and information sharing, music therapy, and supportive touch have been investigated in the literature and may be helpful in reducing patient stress. The advanced practice nurse is instrumental in the assessment of patient-perceived stressors while on the ventilator, and in the planning and implementation of appropriate interventions to reduce stressors and facilitate optimal ventilation, weaning, or both.