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.

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.

Determining the best threshold of rapid shallow breathing index in a therapist-implemented patient-specific weaning protocol.

BACKGROUND: For weaning patients from prolonged mechanical ventilation, we previously designed a respiratory-therapist-implemented weaning protocol that decreased median weaning time from 29 days to 17 days. An acceleration step at the start of the protocol allowed patients with a rapid shallow breathing index (RSBI) of < or = 80 to advance directly to spontaneous breathing trials (SBTs). METHODS: We prospectively evaluated whether calibrating the RSBI threshold allowed more patients to safely accelerate to the 1-hour SBT in the protocol, and whether that correlated with weaning duration and outcome. If the patient passed the clinical stability screening, the respiratory therapist calculated the RSBI and then attempted a 1-hour SBT. If the pre-SBT RSBI was > 80, the SBT was attended by an investigator, with continuous electrocardiography and pulse oximetry. This SBT was followed by continued weaning efforts, as dictated by the weaning protocol. The data were analyzed using receiver operating characteristic curves and univariate and multivariate analyses. RESULTS: One hundred ninety-one patients (with a wide range of RSBIs [10 to 1,248]) underwent 1-hour SBT, of whom 26 failed weaning and 165 succeeded. RSBI correlated with 1-hour SBT outcome; the area under the receiver operating characteristic curve was 0.844. Plotting the sensitivity and specificity together against RSBI allowed calibration of the RSBI threshold to the desired level of false positives and false negatives. Accuracy was maximized (81.7%) at an RSBI of 97. Tolerance of a 1-hour SBT, using the new RSBI threshold, correlated with duration of weaning and weaning outcome. CONCLUSIONS: The conservative RSBI threshold of

Liberation from prolonged mechanical ventilation.

After weaning from PMV, patients are usually far from ready to resume normal activities. A prolonged recovery period after catastrophic illness is the rule, with multidisciplinary rehabilitation and discharge planning efforts. Following such efforts, reports of success of restorative care are institutional and population specific. That all PMV patients are not "chronically critically ill" introduces selection factors that make comparisons between institutions even more difficult. Half of the authors' patients were able to go home in past years [14], although more recently, with patients admitted more debilitated and more ill, the percent returning home has gradually declined to the low 20% range. Bagley et al [11] report discharge to home in 31% of patients weaned. Gracey et al [6,133], treating younger, postsurgical patients, have reported the highest discharge to home rate, 57%; over 70% were eventually discharged to home after first being transferred to a rehabilitation unit. On the other hand, the few reports of survival 1 or more years after discharge are in the 50% range at best (Table 2). Carson and colleagues [9] report a 23% 1-year survival in 133 PMV patients. Their premorbid functional status and age analysis showed younger and more independent patients having a better mortality (56%), and older and more dependent patients having a 95% mortality at 1 year. Nasraway et al [25] report a 1-year mortality of 50.5% in 97 patients transferred from five ICUs to multiple ECFs. Most of these patients would probably meet criteria for PMV, with median time mechanically ventilated 33 days, and 71 ventilator dependent at the time of ICU discharge. A report from 25 Vencor Hospitals [134] not included in Table 2 because weaning outcome was not reported, examines mortality and cost in patients > 65 years of age primarily referred for failure to wean from mechanical ventilation (91% of the cohort of 1619 patients.) There was a 58% in-hospital mortality by day 102 (28 days in the acute care hospital before referral, 74 days in the LTAC afterward), and a 67% mortality in postdischarge follow-up to day 180. Results of functional status studies and quality-of-life (QQL) measures, some using validated instruments, are now being reported in small series of PMV patients. These will merit consideration as important as weaning outcome, disposition, and survival data, as they accumulate to round out the treatment results in this population. Using a proprietary instrument, Carson et al [9] found 42% of 1-year survivors, that is, 8% of study patients, functionally independent at 1 year after discharge. Nasraway [25], using a single-question QQL assessment, and a validated functionality measurement, found 11.5% of his original cohort at home, breathing independently, with a "fair or better" QOL and good physical functionality. In a preliminary report from Dr. Criner's VRU, objective physical improvement was demonstrated in rehabilitation after PMV, using a functional independence measure scale [89]. A full report from the same unit, using a Sickness Impact Profile score makes it clear that PMV had no independent adverse effect on QOL several years later [135]. The 46 patients (25 of whom, with mean age 59 years, responded to the follow-up questionnaire), followed for 24 months after the catastrophic episode, scored their QOL based on their underlying chronic diseases, if any. The older patients, status postsurgical illness, predominantly cardiac surgery, rated their QOL better than younger patients with acute or chronic diseases. Similar findings have been reported in a recent ICU study, reporting QOL after prolonged intensive care [136]. Those who work to liberate PMV patients from mechanical ventilation, a satisfying end in many ways, have demonstrated that this post-ICU critical care activity is usually safe, and successful, although only in observational studies. Will multicenter studies in PMV patients liberated from mechanical ventilation yield facility benchmark, weaning outcome, and survival data that warrant continuation of these activities on a cost-per-outcome basis? That remains to be seen. Assessing and interpreting QOL and functionality findings in these patients, many with underlying chronic diseases resulting in long convalescence and rehabilitation, is a particularly important challenge. The authors are participating in a multicenter study that will yield some of these data; no doubt others will also address these questions. In the mean time, "No one in our society is willing to put Grandma out on an iceberg because she's no longer contributing. Someone needs to take care of these people" [137].

Expiratory asynchrony in proportional assist ventilation.

One of the proposed advantages of proportional assist ventilation (PAV) has been the automatic synchrony between the end of the patient's inspiratory effort and the ventilator cycle (i.e., expiratory synchrony). However, recent clinical studies have shown a prolonged ventilator inspiratory time or even a "runaway" phenomenon with the normal use of PAV. We hypothesize that control-system delay may account for this, because in reality there is always some degree of delays between control-system's input and output in all ventilators. Computer simulation study to date has not taken into account the potential effect of control-system delay on expiratory synchrony. We therefore created a computer model in which the parameter of control-system delay time was introduced. We found that significant expiratory asynchrony may occur with this more realistic model of PAV. The ventilator flow termination may fall behind the completion of the patient inspiration by as long as 0.33 seconds under the selected simulation conditions. The inspiratory termination delay time is in proportion to the control-system delay time, the respiratory time constant, and the assist gain settings. In conclusion, this model indicates that due to the unavoidable control-system delay in the ventilators, expiratory asynchrony may be an inherent shortcoming associated with PAV.