Post-ICU mechanical ventilation at 23 long-term care hospitals: a multicenter outcomes study

STUDY OBJECTIVES: This multicenter study was undertaken to characterize the population of ventilator-dependent patients admitted to long-term care hospitals (LTCHs) with weaning programs, and to report treatments, complications, weaning outcome, discharge disposition, and survival in these patients. DESIGN: Observational study with concurrent data collection. SETTING: Twenty-three LTCHs in the United States. PATIENTS: Consecutive ventilator-dependent patients admitted over a 1-year period: March 1, 2002, to February 28, 2003. RESULTS: A total of 1,419 patients were enrolled in the Ventilation Outcomes Study. Median age of patients was 71.8 years (range, 18 to 97.7 years). Patients averaged 6.9 procedures and treatments during the LTCH hospitalization; median length of stay was 40 days (range, 1 to 365 days). Seven of the 10 most frequent complications treated at the LTCH were infections; congestive heart failure and diabetes mellitus were the most common comorbidities requiring treatment. Outcomes of weaning attempts, scored at LTCH discharge, were 54.1% weaned, 20.9% ventilator dependent, and 25.0% deceased. Median time to wean (n = 766) was 15 days (range, 7 to 30 days). Discharge disposition included 28.8% to home, 49.2% to rehabilitation and extended-care facilities, and 19.5% to short-stay acute hospitals. Nearly one third of patients were known to be alive 12 months after admission to the LTCH. CONCLUSIONS: Patients admitted to LTCHs for weaning attempts were elderly, with acute-on-chronic diseases, and continued to require considerable medical interventions and treatments. The frequency and type of complications were not surprising following prolonged and aggressive ICU interventions. In the continuum of critical care medicine, more than half of ventilator-dependent survivors of catastrophic illness transferred from the ICU were successfully weaned from prolonged mechanical ventilation in the setting of an LTCH.     

Ventilator-dependent survivors of catastrophic illness transferred to 23 long-term care hospitals for weaning from prolonged mechanical ventilation

STUDY OBJECTIVES: This multicenter study was undertaken to characterize the population of ventilator-dependent patients admitted to long-term care hospitals (LTCHs) for weaning from mechanical ventilation. DESIGN: Observational study with concurrent data collection. Characteristics of the LTCHs were also surveyed. SETTING: Twenty-three LTCHs in the United States. PATIENTS: Consecutive ventilator-dependent patients admitted over a 1-year period: March 1, 2002, to February 28, 2003. RESULTS: A total of 1,419 patients were enrolled in the Ventilation Outcomes Study. Median age of the patients was 71.8 years old (range, 18 to 97.7 years), with an equal gender distribution. The premorbid domicile was home or assisted living in 86.5%; "good" premorbid functional status (Zubrod score 0-2) was assessed in 77%. There was a history of smoking in 59% (mean, 57 +/- 42 pack-years [+/- SD]); premorbid diagnoses averaged 2.6 per patient. Patients came to the LTCH after mean of 33.8 +/- 29 days at the transferring hospital; mean time to tracheotomy was 15.0 +/- 10 days. A medical illness led to ventilator dependency in 60.8% of patients; a surgical procedure led to ventilatory dependency in 39.2%. On admission to the LTCH, the median acute physiology score of APACHE (acute physiology and chronic health evaluation) III was 35 (range, 4 to 115); > 90% of patients had at least three penetrating indwelling tubes/catheters; 42% of patients had stage 2 or higher pressure ulceration. CONCLUSIONS: This is the first multicenter study to characterize ventilator-dependent survivors of catastrophic illness admitted to the post-ICU venue of LTCHs for weaning from prolonged mechanical ventilation (PMV). Overall, our findings suggest that ventilator-dependent patients admitted to LTCHs for weaning will continue to require considerable medical interventions and treatments, owing to the burden of acute-on-chronic diseases resulting in PMV.     

Reloading the diaphragm following mechanical ventilation does not promote injury

STUDY OBJECTIVE: Mechanical ventilation (MV) is used clinically to treat patients who are incapable of maintaining adequate alveolar ventilation. Prolonged MV is associated with diaphragmatic atrophy and a decrement in maximal specific force production (P(O)). Collectively, these alterations may predispose the diaphragm to injury on the return to spontaneous breathing (ie, reloading). Therefore, these experiments tested the hypothesis that reloading the diaphragm following MV exacerbates MV-induced diaphragmatic contractile dysfunction, while causing muscle fiber membrane damage and inflammation. METHODS: To test this postulate, Sprague-Dawley rats were randomly assigned to the following groups: (1) control; (2) 24 h of controlled MV; and (3) 24 h of controlled MV followed by 2 h of anesthetized spontaneous breathing. Controls were anesthetized in the short term but were not exposed to MV, whereas MV animals were anesthetized, tracheostomized, and ventilated. Reloaded animals remained under anesthesia, but were removed from MV and returned to spontaneous breathing for 2 h. RESULTS: Compared to the situation with control animals, MV resulted in a 26% decrement in diaphragmatic specific P(O) without muscle fiber membrane damage, as measured by an increase in membrane permeability (using the procion orange technique). Further, there were no increases in neutrophil or macrophage influx. Two hours of reloading did not exacerbate MV-induced diaphragmatic contractile dysfunction or cause fiber membrane damage, but increased neutrophil infiltration, myeloperoxidase activity, and muscle edema. CONCLUSION: We conclude that the return to spontaneous breathing following 24 h of controlled MV does not exacerbate MV-induced diaphragm contractile dysfunction or result in fiber membrane damage, but increases neutrophil infiltration.     

Survival in amyotrophic lateral sclerosis with home mechanical ventilation: the impact of systematic respiratory assessment and bulbar involvement

STUDY OBJECTIVES: To analyze (1) the impact of a protocol of early respiratory evaluation of the indications for home mechanical ventilation (HMV) in patients with amyotrophic lateral sclerosis (ALS), and (2) the effects of the protocol and of bulbar involvement on the survival of patients receiving noninvasive ventilation (NIV). DESIGN AND SETTING: Retrospective study in a tertiary care referral center. PATIENTS: HMV was indicated in 86 patients with ALS, with 22 patients (25%) presenting with intolerance to treatment associated with bulbar involvement. Treatment with HMV had been initiated in 15 of 64 patients prior to initiating the protocol (group A) and in the remaining 49 patients after protocol initiation (group B). RESULTS: In group A, the majority of patients began treatment with HMV during an acute episode requiring ICU admission (p = 0.001) and tracheal ventilation (p = 0.025), with a lower percentage of patients beginning HMV treatment without respiratory insufficiency (p = 0.013). No significant differences in survival rates were found between groups A and B among patients treated with NIV. Greater survival was observed in group B (p = 0.03) when patients with bulbar involvement were excluded (96%). Patients without bulbar involvement at the start of therapy with NIV presented a significantly better survival rate (p = 0.03). Multivariate analysis showed bulbar involvement to be an independent prognostic factor for survival (relative risk, 1.6; 95% confidence interval, 1.01 to 2.54; p = 0.04). No significant differences in survival were observed between patients with bulbar involvement following treatment with NIV and those with intolerance, except for the subgroup of patients who began NIV treatment with hypercapnia (p = 0.0002). CONCLUSIONS: Early systematic respiratory evaluation in patients with ALS is necessary to improve the results of HMV. Further studies are required to confirm the benefits of NIV treatment in patients with bulbar involvement, especially in the early stages.     

Nocturnal noninvasive ventilation

Nocturnal noninvasive ventilation (NNV), the provision of ventilatory assistance via a noninvasive interface mainly during sleep, has assumed an important role in the management of chronic hypoventilatory syndromes. This review focuses on recent developments related to the use of NNV to treat various forms of chronic respiratory failure or insufficiency. In the past, NNV has been used mainly to treat respiratory insufficiency in patients with neuromuscular disease (NMD) or chest wall deformity; it should be instituted when these patients have orthopnea or daytime symptoms associated with nocturnal hypoventilation. An emerging application is to treat obesity-hypoventilation syndrome, particularly in continuous positive airway pressure (CPAP) failures. Additionally, it has a role in managing some patients with obstructive sleep apnea who are hypoventilating or find the lower expiratory pressure with bilevel positive pressure ventilators more tolerable than with CPAP alone. NNV to treat severe, stable COPD remains controversial, although a subgroup of patients with hypercapnea and sleep-disordered breathing (SDB) seems most likely to respond favorably. NNV to treat central SDB in patients with congestive heart failure continues to be investigated. Recent findings from a Canadian CPAP trial were disappointing, but preliminary results on a novel adaptive NNV mode are promising.     

High-frequency oscillatory ventilation for adult patients with ARDS

High-frequency oscillatory ventilation (HFOV) is characterized by the rapid delivery of small tidal volumes (Vts) of gas and the application of high mean airway pressures (mPaws). These characteristics make HFOV conceptually attractive as an ideal lung-protective ventilatory mode for the management of ARDS, as the high mPaws prevent cyclical derecruitment of the lung and the small Vts limit alveolar overdistension. In this review, we will summarize the literature describing the use of HFOV in adult patients with ARDS. In addition, we will discuss recent experimental studies of HFOV that have advanced our understanding of its mechanical properties. We identified 2 randomized controlled trials (RCTs) and 12 case series evaluating HFOV in adults with ARDS. In these studies, HFOV appears to be safe and consistently improves oxygenation when used as a rescue mode of ventilation in patients with severe ARDS. The two RCTs comparing HFOV to conventional ventilation revealed encouraging results but failed to show a mortality benefit of HFOV over conventional ventilation. Further research is needed to identify optimal patient selection, technique, the actual Vt delivered, and the role of combining HFOV with other interventions, such as recruitment maneuvers, prone positioning, and nitric oxide.     

Effects of nocturnal noninvasive mechanical ventilation on heart rate variability of patients with advanced COPD

BACKGROUND: Cardiovascular comorbidities have a negative impact on the health status and prognosis of patients with COPD. We determined whether nocturnal noninvasive (positive) mechanical ventilation (NIMV) can improve heart rate variability (HRV), decrease circulating natriuretic peptide levels, and improve functional performance of patients with very advanced COPD. METHODS: A randomized, double-blind, parallel controlled trial was conducted in 23 participants with stable but advanced COPD. Participants received standard medical therapy plus nocturnal NIMV or standard medical therapy plus sham NIMV for 3 months. RESULTS: After 3 months of NIMV therapy, the 24-h triangular interpolation of N-N intervals increased from 322 to 473 ms (p = 0.034), the 24-h HRV index (HRVI) increased from 21.8 to 29.9 ms (p = 0.035), nocturnal HRVI increased from 6.1 to 8.0 ms (p = 0.026), and the SD of the average N-N interval increased from 37 to 41 ms (p = 0.020). None of these indexes changed significantly in the control group. Additionally, compared with the control group, the pro-atrial natriuretic peptide levels declined significantly in the NIMV group (p = 0.013). CONCLUSIONS: NIMV applied nocturnally over 3 months may improve HRV, reduce circulating natriuretic peptide levels, and enhance the functional performance of patients with advanced but stable COPD. While not definitive due to small sample size, these data suggest that nocturnal NIMV may reduce the impact of cardiac comorbidities in COPD patients.     

The effects of flexible bronchoscopy on mechanical ventilation in a pediatric lung model

BACKGROUND: Flexible bronchoscopy performed through endotracheal tubes (ETTs) in children receiving mechanical ventilation can significantly impact ventilation, but the magnitude of this impact has not been established. We used a lung model to simulate mechanical ventilation in a range of child sizes in order to determine how the insertion of pediatric flexible bronchoscopes into ETTs alters ventilatory parameters, especially tidal volume (Vt) and peak inspiratory pressure (PIP), in both healthy and diseased lungs. METHODS: We simulated five child sizes based on weight, and evaluated 22 bronchoscope/ETT combinations, first in pressure control (PC) ventilation mode and then in volume control (VC) ventilation mode. The combinations ranged from the 2.2-mm (bronchoscope outer diameter)/3.0-mm (ETT inner diameter) to 5.0-mm bronchoscope/8.0-mm ETT. The primary outcome measures were decrease in Vt after bronchoscope insertion during PC ventilation and increase in PIP during VC ventilation. RESULTS: In the PC ventilator mode, Vt decreased by > 50% with nine of the combinations, while during VC ventilation, PIP increased by >or= 20 cm H(2)O with seven combinations. The 2.2-mm bronchoscope/3.0-mm ETT, 2.8-mm bronchoscope/5.0-mm ETT, and 3.6-mm bronchoscope/5.0-mm ETT combinations severely impaired ventilation, while the 3.6-mm bronchoscope/4.5-mm ETT, 5.0-mm bronchoscope/6.5-mm ETT, and 5.0-mm bronchoscope/7.0-mm ETT combinations were incompatible with adequate ventilation. CONCLUSIONS: The insertion of bronchoscopes into ETTs can lead to clinically relevant decreases in Vt when in the PC ventilator mode and large increases in PIP during VC ventilation. The minimum bronchoscope/ETT diameter difference required to maintain adequate ventilation increases with child size.     

Risk factors for ARDS in patients receiving mechanical ventilation for > 48 h

BACKGROUND: Low tidal volume (Vt) ventilation for ARDS is a well-accepted concept. However, controversy persists regarding the optimal ventilator settings for patients without ARDS receiving mechanical ventilation. This study tested the hypothesis that ventilator settings influence the development of new ARDS. METHODS: Retrospective analysis of patients from the Multi Parameter Intelligent Monitoring of Intensive Care-II project database who received mechanical ventilation for > or = 48 h between 2001 and 2005. RESULTS: A total of 2,583 patients required > 48 h of ventilation. Of 789 patients who did not have ARDS at hospital admission, ARDS developed in 152 patients (19%). Univariate analysis revealed high peak inspiratory pressure (odds ratio [OR], 1.53 per SD; 95% confidence interval [CI], 1.28 to 1.84), increasing positive end-expiratory pressure (OR, 1.35 per SD; 95% CI, 1.15 to 1.58), and Vt (OR, 1.36 per SD; 95% CI, 1.12 to 1.64) to be significant risk factors. Major nonventilator risk factors for ARDS included sepsis, low pH, elevated lactate, low albumin, transfusion of packed RBCs, transfusion of plasma, high net fluid balance, and low respiratory compliance. Multivariable logistic regression showed that peak pressure (OR, 1.31 per SD; 95% CI, 1.08 to 1.59), high net fluid balance (OR, 1.3 per SD; 95% CI, 1.09 to 1.56), transfusion of plasma (OR, 1.26 per SD; 95% CI, 1.07 to 1.49), sepsis (OR, 1.57; 95% CI, 1.00 to 2.45), and Vt (OR, 1.29 per SD; 95% CI, 1.02 to 1.52) were significantly associated with the development of ARDS. CONCLUSIONS: The associations between the development of ARDS and clinical interventions, including high airway pressures, high Vt, positive fluid balance, and transfusion of blood products, suggests that ARDS may be a preventable complication in some cases.     

Predictors of survival in COPD patients with chronic hypercapnic respiratory failure receiving noninvasive home ventilation

BACKGROUND: Patients with COPD and chronic hypercapnic respiratory failure (CHRF) are at high risk, and noninvasive ventilation at home is increasingly being used. Knowledge of prognostic parameters under these conditions is limited but may be clinically helpful and highlight the role of noninvasive ventilation. METHODS: In 188 patients with COPD (mean +/- SD FEV1, 31.0 +/- 9.6% of predicted; PaCo2, 56.3 +/- 9.4 mm Hg) discharged from the hospital receiving NIV between July 1994 and July 2004, the prognostic value of body mass index (BMI), lung function, laboratory parameters, and blood gas levels was assessed by univariate and multivariate Cox regression analyses. Moreover, the impact of changes in risk factors on mortality assessed 6.7 +/- 2.8 months after the initiation of noninvasive ventilation was evaluated. RESULTS: Overall, the mortality rate during follow-up (duration, 32.2 +/- 24.3 months) was 44.7%, with 1-year, 2-year, and 5-year survival rates of 84.0%, 65.3%, and 26.4%. Deaths resulted predominantly from respiratory causes (73.8%). Univariate regression analyses revealed age, BMI, hemoglobin, FEV1, specific airway resistance, residual volume (RV)/total lung capacity (TLC), pH, and base excess (BE) to be associated with prognosis (p < 0.01 each), whereas multivariate analysis identified only age, BMI, RV/TLC, and BE as independent predictors (p < 0.05). In patients at risk (BMI < 25 km/m2, RV/TLC >or= 73%, or BE >or= 9 mmol/L), changes in these predictors were also associated with survival. CONCLUSIONS: In patients with COPD and CHRF, nutritional status, hyperinflation, and BE, which turned out to be reliable and consistent markers in CHRF, were independent prognostic factors for mortality. These data favor a multidimensional approach in these patients, including the use of noninvasive ventilation.     

Performance characteristics of 10 home mechanical ventilators in pressure-support mode: a comparative bench study

OBJECTIVE: Inspiratory pressure (Pi) support delivered by a bilevel device has become the technique of choice for noninvasive home ventilation. Considerable progress has been made in the performance and functionality of these devices. The present bench study was designed to compare the various characteristics of 10 recently developed bilevel Pi devices under different conditions of respiratory mechanics. DESIGN: Bench model study. SETTING: Research laboratory, university hospital. MEASUREMENTS: Ventilators were connected to a lung model, the mechanics of which were set to normal, restrictive, and obstructive, that was driven by an ICU ventilator to mimic patient effort. Pressure support levels of 10 and 15 cm H(2)O, and maximum were tested, with "patient" inspiratory efforts of 5, 10, 15, 20, and 25 cm H(2)O. Tests were conducted in the absence and presence of leaks in the system. Trigger delay, trigger-associated inspiratory workload, pressurization capabilities, and cycling were analyzed. RESULTS: All devices had very short trigger delays and triggering workload. Pressurization capability varied widely among the machines, with some bilevel devices lagging behind when faced with a high inspiratory demand. Cycling was usually not synchronous with patient inspiratory time when the default settings were used, but was considerably improved by modifying cycling settings, when that option was available. CONCLUSIONS: A better knowledge of the technical performance of bilevel devices (ie, pressurization capabilities and cycling profile) may prove to be useful in choosing the machine that is best suited for a patient's respiratory mechanics and inspiratory demand. Clinical algorithms to help set cycling criteria for improving patient-ventilator synchrony and patient comfort should now be developed.     

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.     

Diagnosis of nosocomial pneumonia in cancer patients undergoing mechanical ventilation: a prospective comparison of the plugged telescoping catheter with the protected specimen brush.

STUDY OBJECTIVES: Quantitative culture of protected samples of lower respiratory tract secretions obtained by a fiberoptic protected specimen brush (PSB) is widely accepted for the diagnosis of ventilator-associated pneumonia (VAP), but this diagnostic procedure is time consuming, expensive, and may give rise to iatrogenic complications, especially in cancer patients who often present with thrombocytopenia. The plugged telescoping catheter (PTC) could be a satisfactory alternative to the PSB in this setting. The aim of the present study was to evaluate the interest of the PTC to diagnose VAP in ventilated cancer patients. DESIGN: A prospective observational study. SETTING: A 15-bed medical-surgical ICU in a comprehensive cancer center. PATIENTS AND INTERVENTIONS: Over a 9-month period, 42 patients suspected of having bacterial VAP during mechanical ventilation underwent 69 bronchial samplings: a blinded PTC and a fiberoptic PSB were performed successively in each case. A positive culture for both sampling procedures was defined as the recovery of > or = 10(3) cfu/mL of at least one potential pathogen. The PSB result was taken as the reference standard. MEASUREMENTS AND RESULTS: The overall agreement between the techniques was 87% (60/69). PTC had a sensitivity of 67%, a specificity of 93%, a positive predictive value of 71%, and a negative predictive value of 91%. CONCLUSIONS: We conclude that the accuracy of the blinded PTC compares well with that of the PSB for the diagnosis of VAP in cancer patients. The sensitivity of the PTC observed herein, which is slightly lower than that described in previous studies, may be due to the blinded nature of the method: the indications for initial or secondary coupling with a directed sampling method in patients with suspicion of localized pneumonia remain to be determined.     

Impaired objective daytime vigilance in obesity-hypoventilation syndrome: impact of noninvasive ventilation

BACKGROUND: Obesity-hypoventilation syndrome (OHS) is efficiently treated by noninvasive ventilation (NIV). Sleep respiratory disturbances, reduced ventilatory drive, and excessive daytime sleepiness (EDS) are commonly reported, but their relationships remain unclear. OBJECTIVES: To characterize sleep breathing disorders encountered in patients with OHS, to compare low and normal CO(2) responders in terms of sleep abnormalities, subjective and objective measures of EDS, and to measure the changes induced by NIV on these parameters. METHODS: At baseline and after 5 nights of NIV, 15 consecutive patients (mean [+/- SD] age, 55 +/- 9 years; mean body mass index, 38.7 +/- 6.1 kg/m(2); Paco(2), 47.3 +/- 2.3 mm Hg) prospectively underwent polysomnography, CO(2) ventilatory response testing, Epworth sleepiness scale scoring, and the Oxford Sleep Resistance (OSLER) test, which is an objective vigilance test. RESULTS: OHS patients exhibited obstructive sleep apnea syndrome (mean apnea-hypopnea index, 62 +/- 32 events per hour) and rapid eye movement (REM) sleep hypoventilation (mean REM sleep time, 35 +/- 33%). Baseline CO(2) sensitivity was significantly related to the proportion of hypoventilation during REM sleep (r = 0.54; p = 0.037). Six patients showed abnormal sleep latencies during the OSLER test (71% of the low CO(2) responders vs 14% of the normal CO(2) responders). Low CO(2) responders exhibited significantly shorter sleep latencies during the OSLER test (23 +/- 14 vs 37 +/- 8 min, respectively; p = 0.05). Using NIV, diurnal blood gas levels were improved and REM sleep hypoventilation were suppressed. Objective sleepiness was improved in low CO(2) responders (p = 0.04). CONCLUSION: In OHS patients, the lower the daytime CO(2) response, the higher the proportion of REM sleep hypoventilation and daytime sleepiness. Short-term therapy with NIV improves all of these parameters.