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(Chest. 2003;123:2062-2073.)
© 2003 American College of Chest Physicians

Evaluation of a Practice Guideline for Noninvasive Positive-Pressure Ventilation for Acute Respiratory Failure*

Tasnim Sinuff, MD; Deborah J. Cook, MD, MSc (Epi), FCCP; Jill Randall, RRT and Christopher J. Allen, BM, FCCP

* From the Department of Medicine (Drs. Sinuff, Cook, and Allen), McMaster University, Hamilton, ON, Canada; and the Department of Respiratory Services (Ms. Randall), St. Joseph’s Hospital, Hamilton, ON, Canada.

Correspondence to: Deborah J. Cook, MD, MSc (Epi), FCCP, Department of Clinical Epidemiology and Biostatistics, McMaster University, Health Sciences Centre, Room 2C12, 1200 Main St West, Hamilton, ON, Canada L8N 3Z5; e-mail: debcook{at}mcmaster.ca


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Objectives: Clinical practice guidelines have been devised to change practitioner performance and to improve the process and outcomes of care. The objective of this study was to determine whether adherence to a practice guideline on noninvasive positive-pressure ventilation (NPPV) for the treatment of patients with acute respiratory failure (ARF) would change clinician behavior and resource utilization, and improve NPPV utilization and patient outcomes.

Design: Using a multidisciplinary team, we developed, implemented, and evaluated an NPPV practice guideline for ARF. Before and after guideline implementation, we recorded the incidence of endotracheal intubation (ETI) and mortality. Secondary outcomes were technological settings (ie, NPPV settings and duration) and NPPV administration (ie, cardiopulmonary monitoring, transfer to and time spent in the ICU, and pulmonary consultation).

Participants: We enrolled 189 patients, 91 in the preguideline phase and 98 in the postguideline phase. Patients were similar in the both phases with respect to diagnoses at hospital admission and severity of illness.

Results: Of patients receiving NPPV for ARF, 67.3% fulfilled the guideline eligibility criteria in the postguideline phase compared to 62.6% in the preguideline phase (p = 0.543). Compared to the preguideline phase, more patients in the postguideline phase were transferred to the ICU (14.7% vs 33.7%, respectively; p = 0.003), spent more time in the ICU (30.9% vs 62.4%, respectively; p < 0.0001), and had consultation by a pulmonary physician (28.4% vs 49.0%, respectively; p = 0.004). There were no changes in technological settings. Guideline implementation was associated with improved cardiopulmonary monitoring. Nursing and respiratory therapist flow sheets were well-utilized during the guideline phase. There were no differences in ETI rates and mortality rates before and after guideline implementation.

Conclusion: In this before-after study, we found that a multidisciplinary guideline for the use of NPPV for the treatment of patients with ARF was associated with changes in the process of care, with greater NPPV utilization in the ICU, and with increased pulmonary consultation, without any significant changes in the outcomes of care (ie, ETI and mortality rates).

Key Words: acute respiratory failure • noninvasive positive pressure ventilation • practice guidelines


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Noninvasive positive-pressure ventilation (NPPV) has become an accepted treatment for patients with acute respiratory failure (ARF) due to exacerbations of COPD1 and congestive heart failure (CHF).2 The results of a recent meta-analysis3 of NPPV for the treatment of patients with ARF were consistent with those of Keenan et al.1 Following the publication of two systematic reviews, several randomized controlled trials (RCTs) also have suggested that the benefit of NPPV may be extended to patients with pneumonia,4 post-thoracic surgery,5 and postcardiac surgery,6 for the prevention and treatment of postextubation respiratory failure,7 8 as an adjunct to weaning,9 10 in immunocompromised patients with hematologic malignancies11 and in those who have undergone solid organ transplantation.12 However, the evidence for the support of NPPV for these other indications is not yet conclusive. The use of NPPV in patients with asthma13 and exacerbations of cystic fibrosis14 remains controversial, while evidence refutes the use of continuous positive airway pressure (CPAP) in patients with hypoxemic respiratory failure due to ARDS.15

In one retrospective review16 of 75 ARF patients at a community hospital ICU who were receiving NPPV, mortality rates were greater than those reported in RCTs. In that study, the endotracheal intubation (ETI) rate was 37% (28 of 75 patients), with a mortality rate of 65% (18 of 28 patients) among those who did not respond to NPPV. However, 15 of the 18 patients who died had not wanted further resuscitation if they did not respond to bilevel pressure ventilation. In a utilization review at our teaching hospital,17 we also observed that the intubation and mortality rates in patients who had been treated with NPPV were higher than those reported in RCTs (the mortality rate: our COPD population, 23.1%; COPD population of Keenan et al,1 8.9%; our CHF population, 50.0%; CHF population of Pang et al,2 10.1%). We postulated that the reasons for the increased intubation and mortality rates were multifactorial. Half of the patients had NPPV initiated by residents, who had limited training and experience with NPPV, and the cardiac monitoring of these patients was inconsistent. Moreover, the bilevel pressure ventilation machines we utilized lacked tidal volume monitoring capabilities, disconnect alarms, and battery backup systems, thereby precluding the safety benefits that such measures would provide.

The use of NPPV for the treatment of ARF patients outside the ICU and outside the research setting has been cautioned against because of the careful monitoring and comprehensive multidisciplinary education necessary to safely implement this technology.18 The only study to date showing a clear mortality benefit of NPPV outside the ICU setting is that of Plant et al,19 in which the use of NPPV was subjected to a protocol for COPD patients on a specialized respiratory ward (mortality rate, (20% [24 of 118 patients] vs 10% [12 of 118 patients], respectively, for patients treated with standard therapy vs NPPV; p = 0.05). While this study demonstrates that NPPV can be applied successfully outside the ICU, caution should be taken in generalizing the results due to the highly specialized nature of their respiratory units and the protocolization of the application of NPPV. Additionally, staff on the wards had formal skill training and maintenance to provide NPPV. Subgroup analysis also suggested that patients with more severe exacerbations, denoted by a pH of < 7.30, had higher failure rates and hospital mortality rates than did those with a pH > 7.30.

Clinical practice guidelines can optimize the process of care,20 decrease resource utilization,21 minimize unnecessary practice variation,22 and address the issue of delayed application of randomized trial evidence in practice.23 The development of a practice guideline involves the clarification of the purpose of the guideline, the assessment of the clinical appropriateness for target populations, the critique of the scientific evidence, the integration of expert opinion, and, ideally, the commitment to evaluate the impact of the guideline.23 24 25 The objective of this study was to determine whether adherence to a practice guideline on NPPV for the treatment of ARF would change clinician behavior and resource utilization, and improve NPPV utilization and patient outcomes.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Setting
The study was conducted at St. Joseph’s Hospital, a tertiary care teaching hospital in Hamilton, ON, Canada. The hospital is a 386-bed hospital that consists of a 28-bed clinical teaching unit (CTU), 15-bed mixed medical-surgical ICU, an 8-bed coronary care unit (CCU), and a 10-bed respiratory care unit (RCU). The CTU has two teams each composed of an internist, three to five residents in internal medicine and family medicine, and three to five medical students. The ICU team consisted of an intensivist and three to four residents in internal medicine, surgery, or anesthesia. The CCU team consisted of a cardiologist and one to two internal medicine residents. The RCU team consisted of a pulmonary physician and a dedicated nursing staff. The respiratory therapists are not part of a specific team at our hospital, instead, there are two independent teams of respiratory therapists, one of which is located in the ICU, with the other covering the rest of the hospital.

This study was conducted in three phases. The preguideline phase consisted of an 18-month period from June 1997 to September 1998. This first phase involved a retrospective review of the utilization of NPPV for the treatment of patients with ARF at our institution, which we published previously.17 The subsequent 12 months from September 1998 to September 1999 was the guideline development phase. In this second period, we presented the results of the preguideline data collection about the use of NPPV for the treatment of patients with ARF to clinicians and hospital administrators. Subsequently, we developed the guideline, created NPPV educational materials, and assessed the feasibility of guideline implementation in a run-in period. No data were collected during the guideline development phase. The following 18 months from September 1999 to March 2001 was the postguideline phase. In this third period, we prospectively implemented and evaluated the NPPV guideline. This study was approved by the Ethics Review Board of St. Joseph’s Hospital, which waived the need for informed consent

Guideline Development
We developed a multidisciplinary clinical practice guideline for the use of NPPV in patients with COPD and CHF who experience ARF (Fig 1 ). The guideline was created by a team consisting of an intensivist, a pulmonary physician, a respiratory therapist, and a pulmonary/critical care fellow. First, we analyzed the results of our own institutional utilization review of NPPV that had been conducted before the guideline was developed.17 Second, we sought input from the intensivists, pulmonary physicians, cardiologists, and emergency department (ED) physicians, the chiefs of their respective departments and divisions, the nurse managers of the CTU, ICU, critical care unit (CCU), RCU, and ED, and the director of the Respiratory Therapy Department. Third, we critically appraised the RCTs, systematic reviews, and meta-analyses of NPPV in patients with COPD and CHF who had ARF, as well as the NPPV literature for patients with ARF for indications other than COPD and CHF.



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  		Figure 1.. Practice guideline for the use of NPPV in treating patients with ARF who have COPD and CHF. RR = respiratory rate; UGI = upper GI; SBP = systolic BP; CXR = chest radiograph; RT = respiratory therapy; BiPAP = bilevel pressure ventilation; HR = heart rate; SaO2 = arterial oxygen saturation.

 
The following patients were eligible for study according to the NPPV ARF guideline: (1) 18 years of age; (2) had an exacerbation of COPD or CHF; (3) fulfilled specific clinical criteria (ie, ability to protect airway, ability to manage secretions, and respiratory rate < 30 breaths/min); (4) fulfilled gas exchange criteria (ie, pH < 7.35, PaCO2 > 50 mm Hg, PaO2 < 60 mm Hg on fraction of inspired oxygen (FIO2) of 0.21 or a PaO2/FIO2 ratio of < 200); and (5) fulfilled radiographic criteria (ie, no pneumothorax). Contraindications to NPPV were clearly specified, including conditions such as cardiac arrest, immediate need for ETI, upper GI bleeding, and facial trauma (Fig 1) .

During this study, some patients in the postguideline phase received NPPV for the treatment of ARF outside of guideline criteria. These patients had ARF due to asthma, chronic alveolar hypoventilation, restrictive lung disease, neuromuscular disorders, cystic fibrosis, postoperative thoracic surgery, acute hypoxemic respiratory failure, and postextubation respiratory distress or failure, or received NPPV therapy as an adjunct to weaning. Whether the guideline eligibility criteria were fulfilled or not, all consecutive patients receiving NPPV for ARF were identified and observed, and had comprehensive outcome assessments.

Prior to NPPV initiation, the guideline recommended structured clinical assessments by the physician (ie, history, physical examination, and evaluation of guideline eligibility) and beside nurse (ie, history and physical examination), and a clinical and technical assessment by the respiratory therapist. The physician assessment required an evaluation of whether the patients met the guideline eligibility criteria (Fig 1) . Prior to NPPV initiation, a baseline chest radiograph, arterial blood gas (ABG) analysis, and ECG were recommended. For NPPV initiation and stabilization, the guideline required the patient to be transferred to a ward with a nursing ratio of 1:1, appropriate cardiopulmonary monitoring, and respiratory therapist support. In our institution, only the ICU and CCU (for patients with pulmonary edema) locations fit these criteria. During the acute period prior to transfer to the ICU or CCU, the guideline provided that NPPV could be initiated on the ward, provided that a 1:1 nurse/patient ratio was met. The guideline recommended the utilization of a full facemask as the initial interface during the acute phase of NPPV implementation. Consultation with a pulmonary physician was recommended to help determine guideline eligibility, to set the initial NPPV parameters, and to provide follow-up patient care.

A protocol was not provided for the titration of pressure levels, the duration of NPPV utilization, and the weaning from NPPV. Instead, the decisions about the titration of the technological settings, the duration of the application of NPPV, and the weaning from NPPV once patients were stable were left to the discretion of the bedside physicians and respiratory therapists. Our recommendations were to titrate to the highest pressures that the patients could tolerate and to maintain NPPV therapy for as long as patients required, until there were improvements in clinical symptoms and signs and in ABG levels.

Physician order forms were provided to initiate NPPV therapy. Standardized nursing and respiratory therapist flow sheets were used to document technological settings, physiologic responses, and the type of monitoring employed. Medical care was otherwise at the discretion of the physicians, with recommendations for ongoing clinical assessments and optimization of standard medical therapy. Standard medical therapy included, at minimum, bronchodilators, inhaled and systemic steroids, antibiotics for patients with ARF due to COPD, and diuretics for patients with CHF. The guideline also outlined the criteria for ETI.26 Major considerations for ETI included the following: respiratory arrest; respiratory pauses with loss of consciousness (LOC); psychomotor agitation; heart rate of < 50 beats/min with systolic BP of < 90 mm Hg; and decreased level of consciousness. Minor considerations for ETI included the following: respiratory rate of ≥ 35 breaths/min on hospital admission; arterial pH ≤ 7.30 on hospital admission; and a PaO2 < 50 mm Hg despite oxygen therapy.

Guideline Implementation
Guideline Initiation: A multidisciplinary committee of two respiratory therapists, two nurse educators, and a pulmonary/critical care fellow developed and subsequently implemented a structured, standardized NPPV educational program. We provided interactive teaching sessions for nurses (from the ED, ICU, CCU, and CTU), respiratory therapists, and internal medicine and ICU residents. The educational sessions for ICU residents continued throughout the implementation and evaluation phases every 2 months for each new rotation. We also presented the guideline at medical and pulmonary grand rounds. Each of these formal educational sessions was composed of a review of NPPV technology, and the randomized trial literature supporting its use, and a review of the guideline eligibility criteria, NPPV initiation, monitoring, and outcome evaluation, the specific content of which was adapted to the respective health-care practitioner group.

Several reminders were employed throughout the study. We mailed the guideline to all physicians. We placed posters about the NPPV guideline in the ED, ICU, CCU, CTU, and RCU. We displayed the detailed practice guideline outlining the eligibility criteria for and contraindications to NPPV, describing the clinical assessments required by the physicians, respiratory therapists, and nurses, and the baseline chest radiographs, ABG analyses, and ECGs required before the initiation of NPPV.

Guideline Maintenance: Throughout the process of guideline development, implementation, and evaluation, the literature on NPPV for the treatment of patients with ARF was continuously critically appraised and updated by one of the investigators to keep the guideline current. There were no changes made to the patient eligibility criteria since the new evidence supporting the use of NPPV in the treatment of patients with ARF for indications other than COPD and CHF, while incremental and supportive, has not been definitively established, as per the American Thoracic Society-European Society of Intensive Care Medicine Consensus Conference on NPPV.27

After 6 months of implementation, we provided a detailed audit and feedback on NPPV utilization during this period to the ED, ICU, and pulmonary physicians. We revised the physician order forms based on recommendations from the ICU and pulmonary teams. The physician order form was modified to streamline the ordering of the interface (eg, full facemask vs nasal mask), the duration of time allowed for the patient to be off NPPV, oxygen saturation monitoring during NPPV and while not receiving NPPV, and the initial pressure levels (ie, inspiratory positive airway pressure [IPAP] and expiratory positive airway pressure [EPAP]). The respiratory therapists were encouraged with verbal and written reminders to have the ordering physicians (if they were not intensivists or pulmonary physicians) ratify their orders with a consultation to the pulmonary team. Teaching sessions continued every 2 months for the ICU residents. We did not introduce any incentives, disincentives, computer decision support systems, or other guideline implementation strategies during the postguideline phase.

Guideline Evaluation
Prospectively, we collected data in duplicate on all consecutive patients who were admitted to the hospital and began receiving NPPV for the treatment of ARF. Each patient then was classified as either meeting or not meeting the guideline eligibility criteria.

Primary outcomes included ETI and mortality rates. Secondary outcomes included changes in NPPV administration (ie, cardiopulmonary monitoring that includes cardiac monitoring, pulse oximetry, and the ability for ABG procurement), transfer to and total time spent in the ICU, and pulmonary consultation, and technological settings (ie, NPPV settings and duration). All consecutive patients with ARF who received NPPV during the 36-month preguideline and postguideline phases were observed until death or discharge from the hospital.

Statistical Analysis
We present the results as the mean ± SD, or as the median and interquartile range (IQR) if the data are skewed. For primary and secondary outcomes, dichotomous outcomes were analyzed using either the Pearson {chi}2 test with Yates correction or the Fisher exact test for small sample sizes. We analyzed continuous variables using the Student t test. We considered a two-tailed p value of < 0.05 to be statistically significant. We reported ETI rates, all-cause ICU mortality rates, and all-cause hospital mortality rates. In addition, we report the hospital mortality rates excluding patients who received NPPV following a decision to limit the goals of care (eg, to forgo cardiopulmonary resuscitation, or to change the goals of care to palliation or comfort measures). The inclusion of such patients in the mortality analysis would otherwise inflate the association of NPPV with mortality. Analyses were performed using appropriate software (SPSS; SPSS Inc; Chicago, IL).


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Every patient receiving NPPV for ARF in the preguideline and postguideline phases was included in this study. In the preguideline phase, 91 patients underwent 95 trials of NPPV. In the postguideline phase, 98 patients underwent 104 trials of NPPV. Patient characteristics (Table 1 ) were similar with respect to age, gender, most hospital admission diagnoses, neurologic status, and ABG levels (Table 2 ). There were significant differences at baseline with respect to hospital admission diagnoses of acute coronary syndromes, hypoxemic respiratory failure, pneumothorax, and premorbid cardiac disease (Table 1) . The hospital admission diagnoses were primarily cardiorespiratory in both phases. A total of 6 patients in the preguideline phase and 15 patients in the postguideline phase who had do-not-intubate orders, do-not-resuscitate orders, or were receiving palliative care received a trial of NPPV for the treatment of ARF.


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  		Table 1.. Baseline Patient Characteristics*

 

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  		Table 2.. Utilization of NPPV*

 
In the postguideline phase, 66 of the 98 patients who started receiving NPPV fulfilled the guideline criteria. When the same guideline eligibility criteria were applied to patients from the preguideline utilization review,16 57 of 91 of those patients (62.6%) met the guideline criteria (p = 0.543). Unless otherwise specified, the results are presented for the preguideline and postguideline patients as a whole, respectively, rather than in subgroups of those who did and did not meet the guideline criteria.

The number of patients admitted to individual services before and after the guidelines were implemented were similar, with the majority of patients admitted to the general internal medicine, pulmonary, or cardiology services. Guideline implementation did not result in an increase in NPPV orders documented in the chart. Significantly more orders for NPPV were written by internal medicine residents (26.4% vs 45.8%, respectively; p = 0.001), with fewer orders written by pulmonary and critical care fellows (17.3% vs 4.8%, respectively; p = 0.004) in the postguideline phase. The rate of pulmonary consultation was significantly higher during the postguideline phase (28.4% vs 49.0%, respectively; p = 0.004).

We present NPPV utilization in Table 2 . Significantly fewer patients with normal ABG levels (18.9% vs 3.8%, respectively; p = 0.001) began receiving NPPV in the postguideline phase. For those patients with abnormal ABG levels, significantly fewer patients in the postguideline phase were hypercarbic (13.7% vs 1.9%, respectively; p = 0.002). The median duration of NPPV was the same preguideline (4.9 h; IQR, 1.8 to 15.5) compared to postguideline (4.5 h; IQR, 2.1 to 15.7). The NPPV guideline was associated with important changes in the process of care. We outline the location of NPPV initiation in Figure 2 . Most NPPV initiation took place in the ED. However, NPPV was initiated significantly more often in the ICU during the postguideline phase (5.3% vs 23.1%, respectively; p < 0.001). We outline the proportion of total NPPV utilization time in each location in Figure 3 . We found a significant increase in the proportion of the total time that NPPV was used in the ICU during the postguideline phase compared to the preguideline phase (30.9% vs 62.4%, respectively; p < 0.0001). NPPV utilization in the CTU also decreased during the postguideline phase (20.2% vs 3.1%, respectively; p < 0.0001). Fewer patients underwent their entire NPPV trial in a noncritical care location in the postguideline phase (73.7% vs 35.6%, respectively; p < 0.0001), and more patients receiving NPPV were transferred to the ICU in the postguideline phase (14.7% vs 33.7%, respectively; p = 0.003).



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  		Figure 2.. The location of the initial administration of NPPV before and after guideline implementation is shown. Other = surgical ward, intermediate coronary care unit, nephrology ward, geriatric assessment unit, and postoperative anesthetic recovery room; * = p < 0.001.

 


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  		Figure 3.. The percentage of the total time of utilization of NPPV before and after guideline implementation. See the legend of Figure 2 for terms not used in the text. * = p < 0.0001.

 
We found a significant increase in the rate of ABG procurement after the initiation of NPPV therapy in the postguideline phase (47.4% vs 70.2%, respectively; p = 0.001). While there were no significant changes in the technological settings of NPPV, more trials in the postguideline phase were undertaken with the use of a full facemask as the initial interface (12.6% vs 49.0%, respectively; p = 0.007), as per guideline recommendations. As a result, significantly fewer patients received both nasal and full facemasks (17.9% vs 8.7%, respectively; p < 0.0001), after guideline implementation. In most patients in whom both types of interfaces were tried, the nasal mask was tried initially, followed by full facemask if the former failed during both the preguideline and postguideline phases. The maximal IPAP and EPAP levels were not different before and after guideline implementation, respectively (IPAP, 10 mm Hg [IQR, 10 to 12 mm Hg] vs 12 mm Hg [IQR, 10 to 14 mm Hg]; EPAP, 5 mm Hg [IQR, 4 to 6 mm Hg] vs 6 mm Hg [IQR, 5 to 6 mm Hg]; p = 1.00).

In the postguideline phase, nursing and respiratory therapist flow sheets were often utilized (43 of 104 flow sheets [41.3%] and 52 of 104 flow sheets [50.0%], respectively). However, the standardized NPPV physician order forms were used for only 27 of 104 trials (26.0%). A similar proportion of NPPV initiations occurred without a physician order in both the preguideline and postguideline phases (14 of 95 initiations [14.7%] vs 15 of 104 initiations [14.4%]; p = 1.00).

We report the outcomes associated with NPPV for the treatment of ARF in Table 3 . The duration of invasive positive-pressure ventilation, the duration of ICU stay, and the duration of hospital stay were similar in both phases. Overall, the rate of ETI (34.1% vs 43.2%, respectively; p = 0.182) was similar before guideline and after guideline implementation. There was no difference in the rate of ETI among the subgroup of patients with COPD exacerbations (38.7% vs 25.6%, respectively; p = 0.309) or CHF (45.2% vs 23.3%, respectively; p = 0.077). The all-cause mortality rate was the same in both phases overall (28.6% vs 22.4%, respectively; p = 0.390). The mortality rate was not significantly different among patients with COPD exacerbations (23.1% vs 30.4%, respectively; p = 0.747) or CHF (50.0% vs 26.1%, respectively; p = 0.142). The ICU mortality rate was significantly higher after guideline implementation (6.6% vs 12.2%, respectively; p = 0.037) and consisted primarily of patients in whom life support measures were withdrawn in favor of comfort measures or palliation. When patients receiving NPPV following decisions to limit the goals of care were excluded in both phases, the hospital mortality rate was significantly lower in the postguideline phase (21.9% vs 7.1%, respectively; p = 0.006).


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  		Table 3.. Outcomes Associated With NPPV*

 
The ETI and mortality outcomes are also reported according to their subgroups of before and after guideline implementation depending on whether or not the guideline criteria were met. As presented in Table 4 , fewer patients required ETI (24.3% vs 66.7%, respectively; p < 0.0001), with no difference in mortality rate (24.3% vs 27.2%, respectively; p = 0.73), in patients meeting guideline eligibility criteria. In addition, more patients were intubated in the postguideline phase, compared to the preguideline phase, if they did not meet the guideline eligibility criteria (100.0% vs 35.2%, respectively; p < 0.0001).


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  		Table 4.. Outcomes According to Guideline Eligibility Criteria Preguideline and Postguideline*

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Following the introduction of a clinical practice guideline for the use of NPPV in the treatment of patients with ARF, we found significant changes in the processes of care, including more patients being managed in the ICU, improved cardiopulmonary monitoring, and increased consultation by the pulmonary service. Overall, we did not find any significant differences in ETI rates or ICU or hospital mortality. We did, however, find a trend toward less ETI in patients with CHF who had been treated with NPPV. When patients were grouped according to whether they met the guideline eligibility criteria, we found a significant decrease in the rate of ETI in the postguideline phase. All patients not meeting the guideline eligibility criteria in the postguideline phase required ETI.

The higher ETI rate in patients not meeting guideline eligibility criteria reflects the fact that the guideline was successful in helping to reduce the rate of ETI at our institution. The fact that all patients who did not meet the guideline eligibility criteria in the postguideline phase required ETI, supports our hypothesis that the guideline directed physicians to intubate more appropriately in such patients who were not responding to NPPV. In addition, the 100% ETI rate in patients who did not meet the guideline criteria in the postguideline phase further substantiates the validity of the guideline eligibility criteria.

Due to the nonrandomized nature of this study, it is not possible to draw conclusions about the causal nature of whether the NPPV guideline for ARF effected any changes in outcomes, although changes in the process of care did occur. A large, rigorous RCT of guideline implementation would more carefully evaluate the comparability of groups at baseline, and would determine whether a guideline significantly improves patient outcomes. It is useful to evaluate whether guidelines can change, or better yet, definitively improve the processes of care; however, changes in the process of care do not necessarily result in improved outcomes. Because the process of development and implementation of a guideline is complex and its effects can be influenced by a number of factors, bias in a nonrandomized study such as this one limits causal inferences.

While we did not observe a significant difference in overall hospital mortality after guideline implementation, these results should be interpreted in light of an unexpected increase in the utilization of NPPV for patients whose goals of treatment were limited. In the postguideline phase, 15 patients who were receiving palliative care or had do-not-resuscitate or do-not-intubate directives received NPPV, compared with 6 patients in the preguideline phase. When these patients with limited treatment goals were excluded from the mortality analysis, hospital mortality was significantly lower in the postguideline implementation phase (21.9% vs 7.1%, respectively; p = 0.003). Similarly, we identified a significantly higher ICU mortality after guideline implementation and determined that this was primarily due to the withdrawal of life support from some patients receiving NPPV. These results are consistent with the lack of reduction in ETI rates in the postguideline implementation phase of the study, since the RCTs in this area support the fact that the morbidity and mortality reductions were due to reductions in ETI rates. Hence, it is most likely that a greater number of patients chose to forgo advanced life support measures than in the preceding 18 months prior to guideline development and implementation. Additionally, this reflects an increase in the use of NPPV in patients with ARF who had do-not-intubate, do-not-resuscitate, or palliative care directives at our institution after guideline implementation, and who were not part of the inclusion or exclusion criteria of the guideline. The reasons for this increase are uncertain and are currently being addressed in a separate study at our institution.

When patients were grouped according to whether they met the guideline eligibility criteria, we found a significant decrease in the rate of ETI in the postguideline phase. All patients not meeting the guideline eligibility criteria in the postguideline phase required ETI. The higher ETI rate in patients not meeting the guideline eligibility criteria reflects the fact that the guideline was successful in helping to reduce the rate of ETI at our institution. In addition, the fact that all patients who did not meet guideline eligibility criteria in the postguideline phase required ETI supports our hypothesis that the guideline directed physicians to intubate more appropriately in such patients who were not responding to NPPV.

Our NPPV guideline recommended the transfer of patients with ARF who had begun receiving NPPV therapy to the ICU for cardiopulmonary monitoring and ETI when appropriate. Accordingly, we found that ICU utilization significantly increased in the postguideline phase, although total hospital length of stay remained unchanged, reflecting increased adherence to the guideline recommendations. These recommendations were made in this guideline to reflect the resources in our institution, which has a surgical stepdown unit, but not a medical stepdown unit. Additionally, previous randomized trials have shown that NPPV in the critical care setting is associated with a decreased need for ETI4 11 12 26 and with lower rates of pneumonia11 12 28 and mortality.4 11 12 26 However, ICU and CCU beds are not always available for hospitalized patients requiring NPPV. For example, in a multicenter study in Great Britain,19 NPPV for patients with COPD exacerbations was delivered successfully on a pulmonary ward with a protocol driven by specialized pulmonary nurses. Thus, alternative settings such as intermediate care units or specialized pulmonary wards may provide optimal care to patients with ARF requiring NPPV, and may consume fewer institutional resources.

Practice guidelines may be a tool to help improve technology utilization. Our guideline recommended that in patients whose clinical status or ABG values either did not improve or worsened 3 h after NPPV initiation, consideration should be given to the discontinuation of NPPV and to the implementation of ETI. This guideline was intended for patients with a COPD or CHF exacerbation who we considered to be eligible for the guideline, and for whom evidence in support of NPPV is strongest. However, during this study, we recorded all patients who began receiving NPPV, including those who did not meet the guideline eligibility criteria. Our recommendations for the application of NPPV thus were encouraged rather than enforced for patients who did not meet the guideline eligibility criteria because of inconclusive research.27 While there was no change in the rate of ETI among patients with COPD and CHF after guideline implementation, a greater proportion of patients who did not meet the guideline eligibility criteria were intubated in the postguideline phase. We hypothesize that the guideline directed physicians to intubate more appropriately in such patients who were not responding to NPPV.

The technological settings of NPPV did not change between phases in this study; however, more NPPV trials in the postguideline phase were undertaken with the use of a full facemask as the initial interface, as per our recommendation. Both the state of the art review29 and the International Consensus Conference on NPPV27 concluded that there was no consistent evidence to support the use of a particular interface, mode of ventilation, or type of ventilator in the delivery of NPPV to patients with ARF. Thus, we could not incorporate specific recommendations about most NPPV technological issues into our guideline. Until further health technology assessment research informs us about the foregoing issues, clinicians must rely on their experience and clinical acumen to optimize these potentially important aspects of NPPV delivery.27 30

This study raises important issues about clinical practice guidelines for life support technology. With technologies such as NPPV that may be utilized by clinicians with varying degrees of experience and knowledge, a practice guideline ideally does more than "assist practitioner and patient decisions about appropriate health care for specific clinical circumstances."31 Technology guidelines should never replace clinical judgment but can improve the appropriate application of the technology. Technology guidelines have the potential to reduce unnecessary variability in utilization and may encourage practice based on the best current evidence. Our NPPV guideline underwent multidisciplinary development. Its evaluation also fostered the multidisciplinary care of patients with ARF requiring NPPV and an institutional awareness of the need to safely monitor seriously ill patients with ARF. Finally, technology guidelines can serve as educational vehicles for teaching clinicians with different levels of expertise and experience.

In addition, extensive education is usually necessary for optimal guideline adherence.32 33 While guideline development and implementation are complex, changing clinician behavior to maximize the success of a guideline is even more challenging.34 35 In this study, before the NPPV guideline implementation, nurses, respiratory therapists, and residents who were likely to be involved in the utilization of NPPV participated in formal education during a 2-month run-in period. Over the course of the study, we provided ongoing educational sessions to the ICU residents. We did not use verbal, written, or computer-generated reminders or decision supports during this study, although audit, feedback, and reminder systems,32 33 as well as computer decision support systems,36 also effectively influence behavior and can encourage guideline adherence. This NPPV guideline was designed for patients with ARF due to COPD and CHF, for whom the evidence of benefit is strongest and most consistent. Of note, our guideline did not eliminate the use of NPPV for patients for whom there is inadequate support in the literature. In this study, 32.7% of postguideline patients did not meet guideline eligibility criteria, reflecting physician latitude, and the philosophy that a practice guideline guides patient selection rather than dictates practice.

Finally, guideline maintenance is key to the guideline process. Our NPPV guideline was maintained over an 18-month period during the evaluation process. "Evidence-based clinical practice guidelines are living documents. To qualify as evidence-based, they must evolve as new evidence emerges; otherwise, their credibility suffers."34 Guideline maintenance is complex and multifaceted, and may be the key to sustaining the outcome benefits that NPPV can provide in practice. As new evidence emerges about the use of NPPV for treating patients with ARF, we must consider NPPV as an evolving health-care technology, practice guidelines for which updating and improvement are required so that they achieve their full potential to improve the process and perhaps the outcomes of care.


   Acknowledgements
 
We thank the nurses, respiratory therapists, physicians, and residents at St. Joseph’s Hospital for their support of this study. We are grateful to Dr. S.P. Keenan for his critical review of the manuscript, Barbara Hill for her administrative support, Michelle Shilton for her help with the data collection, and the NPPV education committee (Barb Fiorino, Karl Weiss, Gail MacKenzie, and Darlene Saratsiotis).


   Footnotes
 
Abbreviations: ABG = arterial blood gas; ARF = acute respiratory failure; CCU = coronary care unit; CHF = congestive heart failure; CPAP = continuous positive airway pressure; CTU = clinical teaching unit; ED = emergency department; EPAP = expiratory positive airway pressure; ETI = endotracheal intubation; FIO2 = fraction of inspired oxygen; IPAP = inspiratory positive airway pressure; IQR = interquartile range; LOC = loss of consciousness; NPPV = noninvasive positive-pressure ventilation; RCT = randomized controlled trial; RCU = respiratory care unit

Dr. Cook is a Critical Care Chair of the Canadian Institute of Health Research. Dr. Sinuff was supported by a Canadian Institute of Health Research Fellowship Award.

Received for publication January 23, 2002. Accepted for publication October 7, 2002.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

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