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(Chest. 2001;120:482S-484S.)
© 2001 American College of Chest Physicians

Post-ICU Weaning From Mechanical Ventilation*

The Role of Long-term Facilities

David J. Scheinhorn, MD, FCCP; David C. Chao, MD, FCCP; Meg Stearn Hassenpflug, MS, RD and Douglas R. Gracey, MD, FCCP

* From the Barlow Respiratory Research Center (Drs. Scheinhorn, Chao, and Hassenpflug), Los Angeles, CA; and Mayo Clinic (Dr. Gracey), Rochester, MN.

Correspondence to: David J. Scheinhorn, MD, FCCP, Barlow Respiratory Research Center, 2000 Stadium Way, Los Angeles, CA 90026; e-mail: djs{at}barlow2000.org


   Abstract
TOP
 Abstract
Introduction
 Summary Review of Available...
 Discussion
 Conclusion
 References
 
A review of the largest observational studies on post-ICU weaning from prolonged mechanical ventilation yields evidence that more than half of such patients can be successfully liberated from mechanical ventilation. Success is likely to fall within a 3-month window, with late successes and partial ventilator independence still possible thereafter. There is a uniformity of practice in finishing difficult weaning with self-breathing trials of increasing duration.

Key Words: chronically critically ill • post-ICU • prolonged mechanical ventilation • weaning


   Introduction
TOP
 Abstract
 Introduction
Summary Review of Available...
 Discussion
 Conclusion
 References
 
Those patients who fail to wean in the ICU, becoming dependent on mechanical ventilation (up to 20% of patients who received mechanical ventilation in the ICU1 2 ), were transferred to alternative settings with increasing frequency as the past decade came to a close. This trend is in large part a response to the financial pressure brought to bear on hospitals by the prospective payment system for reimbursement. Patients who are ventilator-dependent in the ICU for > 21 days account for 37% of all ICU costs to the hospital,3 a powerful incentive to transfer patients to a lower level of care. This transfer of ventilator-dependent patients out of the ICU has spawned a host of facilities (both for-profit and not-for-profit facilities) to accommodate these prospective payment system outliers.

There are > 30 studies on post-ICU weaning from prolonged mechanical ventilation (PMV). The strength of the available evidence for continued weaning attempts of PMV patients in post-ICU settings is limited to evidence ratings IV and V (ie, nonrandomized studies, historical control subjects, uncontrolled observations, and expert consensus). The studies are virtually all observational single-center studies, as opposed to the more desirable randomized controlled trials and multicenter studies. Why? The heterogeneity of PMV patients mandates a large study cohort for post-ICU weaning and a similarly large control group for continued ICU weaning attempts. Randomizing patients to continued ICU weaning vs post-ICU weaning presents the following challenges: (1) variability in patient-care practice, including weaning, makes it impossible to isolate the weaning milieu as a single "intervention" to be evaluated, thwarting the generalization of study findings; and (2) the logistics of sustaining a large control group until outcome in either one or several ICUs would utilize beds that are needed for newly critically ill patients, which would congest the continuum of care.

Like the patients they serve, facilities accepting patients from traditional ICUs for continued weaning attempts are also heterogeneous. They differ in their admission and discharge criteria, referral sources and patterns, administrative resources, patient-care staffing ratios, diagnostic and therapeutic capabilities, approaches to weaning and patient care (eg, multidisciplinary team), and outcomes reporting.


   Summary Review of Available Evidence
TOP
 Abstract
 Introduction
 Summary Review of Available...
Discussion
 Conclusion
 References
 
Since to our knowledge there are no reports of such rigorously designed studies, we have reviewed observational studies that report outcomes in > 100 patients and in which, according to the Health Care Financing Administration, PMV is defined as >= 21 days of ventilator dependency.4 Table 1 characterizes the population served and displays the demographic information and outcomes of those studies, while Table 2 lists the basic weaning strategies that were used in the units from which that information was available. The units are of the following two basic types. (1) Most, but not all, are licensed as diagnostic-related grouping-exempt, long-term acute-care hospitals, which are required by the Health Care Financing Administration to maintain a mean length of stay of > 25 days. These are most often free-standing hospitals that may have their own ICU. Called regional weaning centers (RWCs) in Table 1 , they serve several to many hospitals in their geographic area. (2) Stepdown units, or noninvasive respiratory-care units (NRCUs), have no requirement for a specific length of stay, usually reside within a host hospital, and serve primarily that hospital. The data from these studies5 6 7 8 9 10 11 12 13 indicate that from 34 to 60% of patients who are discharged from the ICU as being "ventilator-dependent" can be weaned effectively when they are transferred to units dedicated to that activity. Post-ICU units, both free-standing and within the hospital of ICU origin, are characterized by less intensive staffing and less costly monitoring equipment, and therefore generate fewer costs in the care of ventilator-dependent patients per patient-day than ICUs.8 9 11


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  		Table 1. Comparison of Observational Studies, Each With > 100 Patients Transferred for Weaning From PMV*

 

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  		Table 2. Post-ICU Weaning Strategies*

 

   Discussion
TOP
 Abstract
 Introduction
 Summary Review of Available...
 Discussion
Conclusion
 References
 
Given that both types of units deliver acute care, but that not all provide critical care (ie, ICU) interventions and staffing, they are often dissimilar in admission and discharge criteria, treatment capabilities, and the availability of specialty/subspecialty consultation services and procedures offered on site, all of which likely have a significant effect on the reported outcomes of care. While methodological details are given short shrift in these reports, which focus on outcome not process, it is clear that both the patient populations and the facilities are dissimilar. The comparison of observational studies in Table 1 provides evidence to support the recommendation that critical-care practitioners familiarize themselves with community resources. As evidence that such awareness is needed, Nasraway and colleagues14 followed-up direct discharges of ventilator-dependent individuals from the ICU to > 20 extended-care facilities in the Boston area. They found wide variability in the care provided at these post-ICU venues, including considerable variability in available skilled nursing. Although they accepted ventilator-dependent patients from the ICU, levels of care below long-term acute care may not be able to provide for the unanticipated needs of these patients (eg, serious infections), possibly contributing in that report to a 23% readmission rate to a tertiary-care hospital for acute illness within 30 days.14

Both a demonstrable success in weaning and cost considerations have driven the transfer of PMV patients to these facilities, earlier and often while patients are still critically ill.6 13 The patient population is elderly with a slight female predominance, and they carry with them such a broad spectrum of acute and chronic medical and postsurgical problems that they require very specialized and individualized treatment plans and resources. This should drive a transfer decision that not only includes continued weaning but also the availability of specific physician-directed support modalities, such as hemodialysis, wound care, physical therapy, occupational therapy, psychological counseling, and nutritional repletion, to name only a few. Even so, the few reports on subpopulations that were not tabulated herein are instructional. Patients requiring both hemodialysis and PMV rarely are liberated from the ventilator (0 to 13% in two studies with poor survival rates15 16 ). Only 16% of PMV patients with ventilator trigger asynchrony, usually those with very far advanced obstructive disease, were able to be liberated from the ventilator compared to 55% of control subjects.17

Outcome reporting varies among the studies and may create inequalities that appear to be important. An example is the shifting of the locus of death from a unit that does not have its own ICU beds, which probably affects mortality data the most. Patients who experience life-threatening complications, such as sepsis, are transferred to ICU care within the unit when those beds exist, not out to another hospital or back to the ICU of the "surrounding" host hospital. As many of these patients will die, the unit’s mortality figures will be much higher than those of a unit that transfers patients out for renewed ICU care.

Contrasting two of the studies in Table 1 that report results in the greatest number of patients is illustrative of this and other factors that affect outcome. The 1997 report by Scheinhorn et al13 is from an RWC with 49 beds (including 6 ICU beds) comprising 1,123 patients, 23% postsurgical patients who were admitted to the RWC for weaning; 56% of patients were weaned in 39 days, and 28% died in the unit. The 2000 report by Gracey et al9 encompasses 420 ventilator-dependent patients, 75% postsurgical, who were admitted to a nine-bed NRCU unit that had no ICU beds (60% of patients were weaned in 10 days, 6% died in the unit, while an additional 9% were transferred back to ICU care). Postsurgical ICU admissions, patients who are younger and have fewer chronic comorbidities, wean faster from mechanical ventilation (in the Gracey et al9 report, 10 vs 39 days) than older patients with multiple acute and chronic medical diagnoses. Contributing to the strikingly low mortality rate in the study by Gracey et al9 are both the preponderance of postsurgical patients and the absence of ICU beds in the unit. Although these two studies9 13 serve to highlight the differences in the population, there were shared elements in the approach to care. Both studies employed a multidisciplinary rehabilitative approach to treatment and weaning.

With the obvious "apples vs oranges" comparisons within these observational studies, the data arguably support success and safety in weaning in these units: success, in that Table 1 encompasses 3,062 patients, with 1,588 (52%) weaned from PMV in these post-ICU venues; and safety, in that a 69% overall survival rate in this chronically critically ill cohort is an acceptable mortality rate.

Finally, despite differences in patient population and physical plant, the available information on the approach to weaning from PMV in these facilities is remarkably similar (Table 2) . Patients’ ventilator support is gradually reduced using the following common modes: synchronized intermittent mandatory ventilation and pressure support ventilation. Usually at the point of approximately half ventilator support, patients are switched to self-breathing trials of increasing duration. Since most patients receive tracheotomies, tracheal collars are used instead of the familiar T-piece in the ICU to supply oxygen and humidity. While no controlled trials have demonstrated the superiority of this technique, and while the studies in Table 2 contain variations on the theme in the difficult-to-wean patient, most centers choose this older (ie, pre-synchronized intermittent mandatory ventilation) weaning technique. Further, the imposition of a rigid weaning protocol that incorporates these techniques has been shown to decrease the time to weaning and the variability in weaning practice. At an RWC in Los Angeles, the time to wean decreased from 39 days with physician-directed weaning to 17 days with therapist-implemented protocol use.18


   Conclusion
TOP
 Abstract
 Introduction
 Summary Review of Available...
 Discussion
 Conclusion
References
 
Although lacking a benchmark, large observational studies have demonstrated success in weaning patients from PMV following ICU treatment for acute illnesses that are usually superimposed on chronic diseases. Depending on community availability, this successful weaning is accomplished in NRCUs or RWCs, which vary in the type of patient admitted but are consistent in the basic approach to weaning. The cost of care in these units is less than that for care in the ICU. Health-care professionals are just beginning to generate standards of practice/clinical practice guidelines to care for this relatively new population of patients with sustained critical illnesses, who are termed the chronically critically ill.


   Footnotes
 
Abbreviations: NRCU = noninvasive respiratory care unit; PMV = prolonged mechanical ventilation; RWC = regional weaning center


   References
TOP
 Abstract
 Introduction
 Summary Review of Available...
 Discussion
 Conclusion
 References
 

  1. Kurek, CK, Cohen, IL, Lambrinos, J, et al (1997) Clinical and economic outcome of patients undergoing tracheostomy for prolonged mechanical ventilation in New York State during 1993: analysis of 6,353 cases under diagnostic related group 483. Crit Care Med 25,983-988[CrossRef][ISI][Medline]
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  6. Carson, SS, Bach, PB, Brzozowski, L, et al (1999) Outcomes after long-term acute care: an analysis of 133 mechanically ventilated patients. Am J Respir Crit Care Med 159,1568-1573[Abstract/Free Full Text]
  7. Clark, RL, Theiss, D (1997) Prolonged mechanical ventilation weaning, the experience at an extended critical care regional weaning center [abstract]. Am J Respir Crit Care Med 155,A410
  8. Dasgupta, A, Rice, R, Mascha, E, et al (1999) Four-year experience with a unit for long-term ventilation (respiratory special care unit) at the Cleveland Clinic Foundation. Chest 116,447-455[Abstract/Free Full Text]
  9. Gracey, DR, Hardy, DC, Koenig, GE (2000) The chronic ventilator-dependent unit: a lower cost alternative to intensive care. Mayo Clin Proc 75,445-449[ISI][Medline]
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  13. Scheinhorn, DJ, Chao, DC, Stearn-Hassenpflug, MA, et al (1997) Post-ICU mechanical ventilation: treatment of 1,123 patients at a regional weaning center. Chest 111,1654-1659[Abstract/Free Full Text]
  14. Nasraway, SA, Button, GJ, Rand, WM, et al (2000) Survivors of catastrophic illness: outcome of direct transfer from intensive care to extended care facilities. Crit Care Med 28,19-25[CrossRef][ISI][Medline]
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  16. Tafreshi, M, Schneider, RF, Rosen, MJ (1995) Outcome of patients who require long-term mechanical ventilation and hemodialysis [abstract]. Chest 108(suppl),134S[Free Full Text]
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