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* From the Barlow Respiratory Hospital and Research Center, Los Angeles, CA.
Correspondence reprint requests to: David J. Scheinhorn, MD, FCCP; 2000 Stadium Way, Los Angeles, CA 90026; e-mail: djs{at}barlow2000.org
| Abstract |
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Study design: Prospective cohort study with historical control.
Methods: A weaning protocol incorporating the procedures and pace of LTAC weaning was developed using available scientific evidence and expert consensus. After training of staff, collection and analysis of pilot data, and revisions and refinement of the protocol, the TIPS protocol was implemented hospital-wide. It was monitored for outcome, variance, and respiratory care practitioner (RCP) and physician compliance.
Results: Forty-six RCPs worked with eight pulmonologists treating 271 consecutive patients admitted for weaning from PMV during an 18-month period. Nineteen patients were excluded from weaning attempts by any method after initial physician evaluation. The remaining 252 patients (9,135 total ventilator days) were compared with a group of 238 patients treated by the same physicians in the 2 years before instituting protocol weaning. Median time to wean declined significantly from 29 days in historical control subjects to 17 days for TIPS protocol patients (p < 0.001). Outcomes (scored at discharge) were comparable for the two groups (TIPS group vs control group): weaned, 54.7% vs 58.4%; ventilator-dependent, 17.9% vs 10.9%; died, 27.4% vs 30.7% (p = 0.10). Variances incurred by physicians and RCPs were 324 and 136, respectively, for the 9,135 ventilator days.
Conclusions: Patients weaned from PMV using a new therapist-implemented protocol at BRH, an LTAC facility specializing in weaning, had significantly shorter time to weaning than historical control subjects, with comparable outcomes. The weaning outcome data collected after the implementation of the TIPS protocol are in fact attributable to its use, as we found a high degree of compliance with the protocol.
Key Words: compliance long-term acute care outcome prolonged mechanical ventilation protocol respiratory care practitioner therapist-implemented time to wean variance weaning
| Introduction |
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| Materials and Methods |
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To give patients the opportunity to progress in weaning as fast as
possible, three "acceleration" steps were incorporated into the
protocol. At each of the following steps, a patient could progress
faster than one step daily: (1) allowed reduction of SIMV to its lowest
level in one step, if PSV breaths were adequate in volume (TIPS
footnote "c"); (2) the rapid shallow breathing index (RSBI)
measurement, if
80 (before step 1), allowed moving directly to the
first SBT; and (3) a patient tolerating any of the SBTs was allowed to
extend the trial through the duration of the next step (TIPS footnote
"e").
During an 8-month pilot period, the protocol was introduced with both
formal and informal education of RCPs, physicians, nurses, and other
caregivers. A "frequently asked questions" file was created to make
consistent responses readily available. Experienced senior RCPs (lead
RCPs) met each weekday morning with the investigators to allow for
problem solving and provide feedback for protocol revision. During the
subsequent 18 months of protocol use, the following procedure was used
to collect data and as an audit tool to measure compliance: The
patients RCP documented the results of the screens (DE and WA) on the
patients respiratory care flow sheet, the subsequent action taken,
and its outcome. An investigator made rounds with the lead RCP daily to
be sure that all data were recorded accurately; the lead RCP
transferred this information to a data collection form. The database
created was analyzed to score patients weaning progress and variances
from the protocol by physicians and RCPs, creating a weaning history
for each patient. TIPS protocol outcome monitors were adopted by the
hospital Organization Performance Review Committee and routinely
reviewed. Statistical tests used to compare TIPS patients and those of
the 2-year historical control included the following:
2 test for weaning outcomes; Mann-Whitney test
of two independent groups for comparison of age, acute physiology score
of the acute physiology and chronic health evaluation (APACHE) III,
prior ventilator time in the ICU, and length of stay (LOS) and time to
wean at BRH. Median values are reported.
| Results |
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Protocol Outcome
Two hundred fifty-two patients entered the protocol, incurring a
total of 9,135 ventilator days. The individual patients weaning
histories, and the medical records of all patients who died were
reviewed, with no evidence found that reduction of ventilator support
by protocol step contributed to any patient death. Outcomes were as
follows: 138 patients were weaned, 45 patients failed to wean, and 69
patients died. The historical control subjects consisted of 238
patients admitted for weaning in the 2 years before institution of the
TIPS protocol, after similar exclusion criteria were applied.
Comparisons to historical control subjects, with outcomes expressed as
percentage, are shown in Table 1
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Differences in time to wean and LOS achieved statistical significance.
The most dramatic finding is the shortened time to wean, from 29 to 17
days (p < 0.001), along with a reduced interquartile range, from 30
to 19 days (Fig 2
). Fifty-two patients
(38% of those who were weaned; 20.6% of all patients) progressed
straight through the protocol without interruption or backtracking;
average time to wean for this group was 11.3 ± 4.3 days. The effect
on LOS for the three outcome groups is as follows (median, TIPS group
vs control group): weaned, 38 vs 50 days; ventilator-dependent, 53 vs
87 days; died, 45 vs 39 days. Overall median LOS at the LTAC was 42.5
days for TIPS protocol patients and 49 days for control subjects
(p < 0.05).
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80.
Sixty-one performed a 1-h SBT per protocol, of whom 54 (89%)
successfully completed the trial. Of the seven patients who failed,
five developed distress during the SBT and two failed because of oxygen
desaturation.
Utility of Routine Arterial Blood Gas
The utility of a routine arterial blood gas (ABG) test after the
first 2 h of SBT was analyzed. One hundred sixty-five ABG tests
were performed. Of these, only 17 (10.3%) prompted actions. Findings
included unexpected hypoxemia (PO2 < 50 mm
Hg) in seven patients, hyperoxia (PO2 > 170
mm Hg) in four patients, and acidemia (pH < 7.30) caused by
hypercarbia in six patients.
| Discussion |
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intervention
assessment. The outcomes of weaning patients from PMV presented above
were attained with a new therapist-implemented protocol, and in the
setting of an LTAC. Gluck7
forecast the possibility of
success in this when he said that protocols "allow some part of the
expertise of physicians to be present at the bedside of weaning
patients continuously." In this manner, the TIPS protocol imposed
organization and standardization of the weaning process combined with
the 24-h availability of a team of caregivers attending to each
patient.
Compliance
Scoring of compliance is essential to the analysis of protocol
results to assure outcomes are the result of protocol use, not variance
from the protocol, or a combination of the two. Ely and
coworkers8
recently analyzed compliance with a large
clinical therapist-implemented weaning protocol, dissecting compliance
barriers and demonstrating the importance of educational reinforcement
in improving implementation. As shown in Table 2
, variance from the
TIPS protocol by physician order occurred in very few of the TIPS
protocol steps in > 9,000 ventilator days. The majority of the
physician variance episodes involved halting the weaning process (mean
time, 7.7 days) because of patient medical status worsening, which
impacted tolerance of weaning, or was expected to do so. These were
appropriate interventions in patient care, after which a recovering
patient went on to outcome in the protocol. In some of these instances,
it became clear that the daily screens would have automatically held
the protocol and that physician "hold" and then "resume" orders
were not necessary. On the other hand, in nearly 25% of these
variances, patients became too ill to ever resume weaning efforts,
remaining ventilator-dependent or dying.
A less frequent type of physician variance was one in which screens were modified, or steps were bypassed or modified. These reflect the fact that, because of patient diversity, even the most robust protocol cannot encompass all patients. A patient with restrictive lung disease, for example, may only be comfortable breathing at a respiratory rate > 35 breaths/min, outside of the WA screen; the physician then would modify that part of the screen to allow the patient to progress. Unsurprisingly, Table 4 shows that physician variance is patient-driven, in that patients who wean easily do not generate as many variances as those who do poorly. It also shows that modifying the protocol does not necessarily result in a successful outcome.
Table 3 shows that RCP variances were of two significant types: not following a step dictated by the protocol, and omitting an ancillary test or procedure dictated by the protocol. The number of episodes of noncompliance was very low, especially considering that in addition to procedures, there were 19 therapist-implemented weaning steps in the protocol. In comparison, the large study cited above, by Ely et al,8 had only two steps on which RCP compliance was scored. Omission of ancillary tests, of which there were few, and documentation errors accounted for the majority of the variances from our protocol. On the other hand, because not every protocol action was documented or verifiable, we were not able to monitor all aspects of RCP performance. RCP aggressiveness, communication skills, and, importantly, the weight of the therapist-implemented step in ICU studies (eg, "extubate patient") impact RCP compliance greatly.9 Figure 3 shows how over time, with continued teaching and reinforcement, both physician and RCP compliance steadily improved.
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Patients were always allowed to extend SBTs historically, if they were tolerating the trial and wished to continue. Addition of the other two acceleration steps, however, was new compared with historical practice, and may have contributed to faster weaning. The physiologically sound principle, namely, that if patient-supported PSV breaths are of sufficient volume, there is no need to reduce SIMV breaths stepwise, had been used for many years by the physicians, but probably not with the consistency that the protocol dictated. The widespread adoption of some form of the RSBI of Yang and Tobin11 as a measure of readiness for SBTs in the ICU setting made incorporation of its use attractive, with an intentionally conservative threshold value recalculated from the original data of Yang and Tobin to identify PMV patients ready for such a trial.12 As an accelerant step with a threshold of 80 breaths/min/L, it allowed almost 90% of those who passed it to successfully skip to SBTs. Further study is warranted to see whether a higher threshold would allow more patients to safely skip ventilator-reduction steps. Retrospectively looked at as an outcome predictor, if the values were 80, 81 to 120, or > 120 breaths/min/L, then 72%, 57%, and 42%, respectively, of PMV patients went on to wean, again with weaning outcome scored at discharge from BRH.13 Only 10% of the single ABG determination picked up blood-gas or acid-base abnormalities requiring action. Because noninvasive capnography was not used, it remains a valuable safety net to identify patients with central hypoventilation not clinically identified.
Both patients weaned with the TIPS protocol, as well as those who remained ventilator-dependent, had fewer ventilator-dependent days and a shorter LOS in the LTAC hospital (Table 1) . With the similarities of the TIPS and the control population noted above, these results in patients who weaned may be attributable largely to the organizational effects of the protocol. By this is meant the persistent daily application of both readiness and tolerance screens, followed by therapist-implemented decrease in ventilator support, with follow-up of tolerance. Standardized ventilator-support reduction, imposed by the protocol, resulted in significantly less variability in time to wean as well (Fig 2) . The availability of computerized weaning histories may be responsible for earlier transfer of ventilator-dependent patients from the LTAC to lower levels of care. It is more likely, however, that increased utilization review pressure, owing to cost concerns, resulted in this finding.
LOS is only affected indirectly by shorter time to wean, because after successful weaning, patients spend 2 to 4 weeks in inpatient pulmonary rehabilitation. This highly variable period of hospitalization depends on the physical status of the patient and their medical needs apart from ventilatory ones, nosocomial complications, what their third-party payer will allow, and placement problems at discharge.
Faster weaning for a greater percentage of patients reduced ventilator days in the weaned group by an average of 16.1 days, saving 1,112 ventilator days in 70 patients per year. In the patients who remained ventilator-dependent, the reduction, presumably occasioned by earlier identification of lack of progression, was 25.9 days, for a total of 570 ventilator days of hospitalization saved per year in 22 patients. Because prior time ventilated was the same as for the historical control patients, cost of treatment per protocol should be less for the entire episode of ventilator-dependent illness.
| Conclusion |
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| Acknowledgements |
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| Footnotes |
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Received for publication February 29, 2000. Accepted for publication June 5, 2000.
| References |
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