Health technology assessment in the ICU: Noninvasive positive pressure ventilation for acute respiratory failure

Health Technology Assessment in the ICU: Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Tasnim Sinuff and Deborah J. Cook Critical care practitioners have a number of healthrelated technologies at our disposal to provide the best possible care for our critically ill patients. Although certain technologies may improve outcomes in the intensive care unit (ICU), many technologies are disseminated without rigorous evaluation. Health technology assessment (HTA) in critical care is a complex and dynamic process, which is a powerful tool to assess a health technology for its initial use or continued application in the ICU. This article applies an HTA framework to the use of noninvasive positive pressure ventilation (NPPV) for patients with acute respiratory failure (ARF). The strongest evidence to date supports the use of NPPV in patients with ARF caused by exacerbations of chronic obstructive pul-

monary disease (COPD); the benefit for patients with acute nonhypercarbic, hypoxemic respiratory failure is less clear. The success of NPPV technology depends on operator education and experience. The cost effectiveness of NPPV has been evaluated in patients with ARF caused by COPD, and cost reduction is attributed to the prevention of ventilator-associated pneumonia by avoiding endotracheal intubation. An HTA framework can help health care practitioners make important decisions regarding the acquisition of new technologies and the evaluation of current technologies. Careful evaluation of health technologies in the ICU should be an ongoing priority. Copyright 2003 Elsevier, Inc. All rights reserved.

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N THE INTENSIVE CARE unit (ICU), lifesupport technology interventions account for 5% to 10% of acute care hospital beds,1 with current demands projected to increase in the future, and the expectation that such technologies will impact favorably on our aging population.2 These therapies include noninvasive positive pressure ventilation (NPPV), high-frequency oscillatory ventilation, and continuous renal replacement therapy. It is the potential for new health care technologies to improve morbidity and mortality in critically ill patients that invokes such enthusiasm for incorporating them in the ICU. However, although the availability of new therapies marks the potential for improved patient outcomes, many technologies have been disseminated in the ICU setting before they have been evaluated rigorously. Yet when they have been evaluated, it often has been difficult to show their effectiveness.3 The implementation of technology in the ICU presents an interesting paradox4 in that many new technologic interventions that were met initially with enthusiasm have later been shown to have the potential for harm. Such examples include observational evidence of increased mortality from the use of the pulmonary artery catheter5; and evidence that specific methods of mechanical ventilation (such as high tidal volume and 0 or low positive end-expiratory pressure) are associated with biotrauma,6 organ dysfunction,7 and ventilator-induced lung injury8 in patients with acute respiratory distress syndrome. Accordingly, health technologies in the ICU require the same evaluation as drug therapies.9 Intensivists have a mandate

to assess rigorously not only the therapeutic technologies but also the diagnostic and monitoring technologies we use in practice.10 NPPV for the treatment of patients with acute respiratory failure (ARF) represents a relatively new therapeutic technology that has undergone some rigorous evaluation. However, it often is used in practice for patients in whom it may provide no benefit.11 With the burgeoning evidence supporting the efficacy of NPPV in select patients with ARF, critical care practitioners are left with a technology that has not undergone a thorough critical evaluation for all populations in all settings. Although there is increasingly convincing evidence that NPPV can reduce the rate of endotracheal intubation and mortality in certain subgroups of patients,12 before it is widely accepted as an alternative therapy to endotracheal intubation (ETI), it requires a comprehensive technology assessment.

Journal of Critical Care, Vol 18, No 1 (March), 2003: pp 59-67

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From the Departments of Medicine and Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada. Supported by a Research Fellowship award from the Canadian Institute for Health Research (T.S.). D.C. is a Critical Care Chair of the Canadian Institute for Health Research. Address reprint requests to Tasnim Sinuff, MD, FRCPC, Department of Medicine, Divisions of Critical Care and Respirology, Firestone Institute for Respiratory Health, St. Joseph’s Health Care, 50 Charlton St E, Hamilton, Ontario, Canada L8N 4A6. E-mail: [email protected]. Copyright 2003 Elsevier, Inc. All rights reserved. 0883-9441/03/1801-0012$30.00/0 doi:10.1053/jcrc.2003.YJCRC12

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SINUFF AND COOK

HEALTH TECHNOLOGY ASSESSMENT

Health technology assessment (HTA) is a complex, multifaceted, and dynamic process requiring continuous evaluation. In general, requisite components of an HTA include “the collection or generation of information about a technology, a synthesis and critical analysis of that information in the context of the policy decision to be made, and presentation of the results in language relevant to the decision.”9 To determine whether to adopt a new therapeutic technology in the ICU or to continue the use of a current therapeutic technology, we therefore need to adopt an outcomes-based approach that incorporates a review of pertinent best current evidence. Within the context of an HTA in the ICU setting there are a number of outcomes to consider including any or all of the following: (1) primary clinically important outcomes such as ETI rate, duration of mechanical ventilation, length of ICU and hospital stay, ICU and hospital mortality, and (2) secondary clinical and other outcomes including physiologic outcomes, ease and practicability of application of the technology, and cost effectiveness. A systematic review of the literature is the most common type of integrative article that provides health care practitioners, educators, researchers, and administrators with a summary of the best available evidence addressing a specific clinical question.13-15 Although performing a formal systematic review of the literature rarely is feasible for and not within the expertise of the busy clinician, the availability of this tool in the literature provides critical care clinicians with a valuable resource to evaluate whether a new technology warrants acquisition or an existing technology warrants continued use. HTA can be considered another clinical tool used to systematically and rigorously evaluate technology. It may be even more time consuming than conducting a systematic review because HTA transcends the randomized controlled trial (RCT) evidence and ideally integrates other levels of evidence including observational studies, utilization reviews, cost-effectiveness analyses, and practice guidelines. Although the scope of HTA is very broad, this article applies a practical, evidence-based, clinically relevant framework of health technology as-

Table 1. Framework for Clinical Evaluation of a Therapeutic Technology What is the efficacy of the therapeutic technology? Has the technology been evaluated rigorously in clinical RCTs? Does the technology improve outcome compared with current best practice? What is the impact of the therapeutic technology? How large are the treatment effects and what is the precision of the estimates of the treatment effect? Is there a range of possible uses of the therapeutic technology? Can I apply the therapeutic technology in my practice? Can I expect a similar benefit in my clinical setting? Were clinically important outcomes considered? Are the outcomes of the therapeutic technology dependent on: Guidelines, protocols Operator (experience, discipline) Hospital location Has the health resource use of the technology been evaluated adequately? Health care practitioner time Cost effectiveness

sessment to NPPV for patients with ARF. We will use an approach different than a systematic review of the literature,15,16 incorporating several additional features of technology assessment that are important for intensivists. A FRAMEWORK FOR THE ASSESSMENT OF A THERAPEUTIC TECHNOLOGY

Because a specific approach for evaluating therapeutic technologies is not available, we developed a framework for the assessment of a therapeutic technology (Table 1). We created this by adapting the validity criteria for assessing a therapy17,18 and from guides used to assess the validity, accuracy, and applicability of studies used to assess diagnostic technologies.19-21 We developed this framework to provide a practical bedside tool for the busy intensivist when assessing the use of therapeutic technologies in the ICU. The assessment of a therapeutic technology involves 4 steps, summarized by the questions in Table 1. More detailed technical components of HTA also are possible but are outside the scope of our approach. Importantly, safety considerations should be central to a thorough HTA, and will be specific to the individual technology under evaluation.

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CLINICAL CASE PRESENTATIONS

You are faced with 2 patients in the ICU— one in which you are already using NPPV for ARF (clinical scenario 1) and another in which one of your ICU residents has asked if NPPV would be worth a trial (clinical scenario 2). Clinical Scenario 1 You receive a patient with an acute exacerbation of chronic obstructive pulmonary disease (COPD) in transfer to your ICU from the Emergency Department (ED). The respiratory therapist sets up bilevel NPPV through a full face mask, using the Vision bilevel positive airway pressure (BiPAP) machine (Respironics, Pittsburgh, PA), asking you if you would like to continue its use as initiated by the emergency room physician. The patient presented to the ED in extremis after 3 days of worsening exertional dyspnea and cough with purulent sputum production. The emergency room physician initiated a trial of bilevel NPPV after the procurement of an arterial blood gas, chest radiograph, and 12-lead electrocardiogram. There was chest radiograph evidence of hyperinflation and a left lower lobe consolidation. You note the absence of a pneumothorax. The electrocardiogram does not suggest acute myocardial ischemia or infarction. You decide to continue the NPPV trial overnight in the ICU. The ICU resident asks you whether there is a reduction in the ETI and/or mortality rate associated with the use of NPPV compared with standard medical therapy alone. Clinical Case Scenario 2 While on rounds this morning, the respiratory therapist just informs you that the patient with previous acute lung injury caused by pneumonia extubated yesterday morning is increasingly dyspneic, tachypneic, tachycardic, and diaphoretic. The respiratory therapist suggests a trial of NPPV. You recall a recent RCT published on the use of NPPV for postextubation respiratory distress. While you examine the patient for clinical signs of diaphragmatic failure, your ICU fellow performs a Medline search for the article. HEALTH TECHNOLOGY ASSESSMENT APPLIED TO NPPV

We will now apply our HTA framework to NPPV.

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What is the Efficacy of the Therapeutic Technology? Has the technology been rigorously evaluated in clinical RCTs? To determine with confidence whether a therapeutic intervention provides benefit over standard medical therapy, valid and adequately powered randomized trials are needed. The validity assessment of such trials should include evaluation about randomization, concealment of the allocation process, the use of blinding where possible, and adequate follow-up.17 There have been 20 published clinical RCTs assessing the use of NPPV in patients with ARF22-41; one nonrandomized controlled trial of NPPV for ARF in COPD patients42; one RCT assessing the use of continuous positive airway pressure in patients with ARF; and a recent meta-analysis update of 15 RCTs.12 NPPV has been assessed more extensively in patients with ARF caused by exacerbations of COPD than in those with acute hypoxemic, nonhypercarbic respiratory failure. Thirteen RCTs included patients with ARF caused by COPD exacerbation.22,25,27,28,31-33,35,36,38-41 The studies examining patients with acute hypoxemic, nonhypercarbic respiratory failure are fewer in number and include a heterogeneous population.23,24,26,28-31,34,37 There are 5 RCTs on the use of NPPV for weaning patients, one included patients with COPD,43 one with a more heterogenous population of patients with acute on chronic respiratory failure,44 the third that included all patients with persistent weaning failure,45 the fourth that included patients failing a 30-minute T-piece trial,46 and the fifth included patients who were extubated after a successful 2-hour T-piece trial.47 To date, there are 3 studies examining the use of NPPV in patients with postextubation respiratory failure,48-50 and 2 studies on the use of noninvasive proportional assist ventilation.51,52 Does the technology improve outcome compared with current best practice? The evidence to date supports the use of NPPV for patients with ARF with COPD exacerbations. The meta-analysis update by Peter et al12 showed an overall reduction in the ETI rate (risk difference [RD] of ⫺0.19 [95% confidence interval of ⫺0.28 to ⫺0.09]) and mortality (RD of ⫺0.08 [⫺0.16 to ⫺0.01]), compared with standard medical therapy. When the

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COPD subgroup analysis was performed for patients with COPD exacerbation, the benefit was substantiated for patients with COPD, with a reduction in ETI (RD of ⫺0.18 [⫺0.33 to ⫺0.03]) and mortality rates (RD of ⫺0.13 [⫺0.21 to ⫺0.06]). The location of the studies is variable and includes the ICU, postanesthesia care unit, the ED, and the respiratory ward. Although the evidence for the use of NPPV in the ICU setting is supported by the studies summarized by Peter et al,12 the data are not supportive in the study by Wood et al34 with respect to the outcomes of ETI and mortality, the use of NPPV outside of the ICU, and uncertainty about the potential contribution of the ventilator and mask type to the study outcomes. This study was performed in the ED and raised questions about the use of NPPV outside the critical care setting because there was no improvement in the rate of ETI, although there was a trend toward increased mortality. Additionally, both ICU ventilators and BiPAP machines were used; the interface used included a combination of either a full face or nasal mask. A single RCT by Navaseli et al53 comparing an oronasal (full face) mask with a nasal mask in trials of NPPV in COPD patients with chronic respiratory failure found that the PaCO2 was reduced to a greater extent with the oronasal mask, whereas the nasal mask was better tolerated. There are fewer studies on the use of NPPV in patients with hypoxemic ARF not caused by a COPD exacerbation and they provide inconsistent results. The studies published to date23,24,26,28-31,34,37 have been performed in heterogeneous patient populations, showing mixed results. Some of these have been summarized in the meta-analysis update by Peter et al,12 who presented their results of a subgroup of mixed patients that did not include patients with an acute exacerbation of COPD. The clear benefit of NPPV for patients with ARF caused by COPD exacerbation is no longer apparent in non-COPD patients with acute hypoxemic respiratory failure. What is the Impact of the Therapeutic Technology? How large are the treatment effects and what is the precision of the estimates of the treatment effect? The size of the treatment effect is important in the consideration of the benefit of any technologic intervention in the ICU setting. The impact of an

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intervention in the critical care setting often is difficult to evaluate because of many confounding factors. To decrease ETI and mortality with the use of NPPV compared with standard medical therapy, the treatment effect should be large in magnitude and precise. Usually, for both of these criteria to be met, the study design should minimize random error and be large in size. Meta-analysis of randomized trials12 allows for a more accurate estimate of the treatment effect than what can be estimated from a single RCT. Both the magnitude and precision of the treatment effect are clearly highest for studies of patients with COPD exacerbations compared with patients with hypoxemic ARF (Table 2). These data provide convincing results and increase our confidence in the use of NPPV in the subgroup of COPD patients. Is there a range of possible clinical indications of the therapeutic technology? Some technologies are applied in situations for which they were not intended initially; this phenomenon is referred to commonly as utilization drift. NPPV now has been evaluated through RCTs and meta-analyses for several clinical indications (including COPD exacerbations, hypoxemic respiratory failure of various etiologies, weaning from invasive mechanical ventilation, and postextubation respiratory failure). Data for the use of NPPV in other subgroups of patients with ARF is not as robust, and hence, we are less confident in our use of NPPV in non-COPD patients. The benefit for the use of NPPV has been shown clearly for patients with ARF caused by COPD exacerbations.12 However, the efficacy of NPPV for other patient populations has not been convincingly shown. There are 2 rigorous RCTs in patients with hematologic malignancies and pulmonary infiltrates26 and solid-organ transplant recipients.29 These studies provide supportive evidence for the use of NPPV in these patients with benefit in terms of reduction in both ETI and mortality rates. The application of NPPV for indications including weaning and postextubation respiratory failure remain uncertain with results of RCTs being inconsistent.43,44,48,49 Factors that may contribute to the inconsistent outcomes of these RCTs include the fact that they have small sample sizes, include heterogeneous patient populations, and the methodologic rigor of the individual RCTs is variable.

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Table 2. ETI and Mortality Rates of Meta-Analysis and RCT Evidence for NPPV for ARF Study

Peter et al12

Peter et al12

Hilbert et al26 Antonelli et al29 Confalonieri et al31 Confalonieri et al31 Martin et al28 Martin et al28

Study Type/ Sample Size

MA 8 studies 793 patients MA 7 studies 247 patients RCT 52 patients RCT 40 patients RCT 23 patients RCT 33 patients RCT 23 patients RCT 29 patients

Patient Population

ETI RD (P Value)

Hospital Mortality RD (P Value)

COPD

.18 (P ⫽ .02)

.13 (P ⫽ .001)

Non-COPD

.22 (P ⫽ .001)

.0 (P ⫽ .98)

Hypoxemic ARF*

.37 (P ⫽ .03)

.31 (P ⫽ .02)

Hypoxemic ARF†

.50 (P ⫽ .002)

.20 (P ⫽ .17)

COPD with CAP

.46 (P ⫽ .005)

.10 (P ⫽ .59)

Non-COPD with CAP COPD

.10 (P ⫽ .73)

.14 (P ⫽ .47)

.20 (P ⫽ NS)

.0 (P ⫽ NS)‡

Non-COPD

.40 (P ⫽ .01)

.29 (P ⫽ NS)

*Immunosuppressed with pulmonary infiltrates. † Solid-organ transplant recipients. ‡ ICU mortality reported. Abbreviations: ETI, endotracheal intubation; RD, risk difference; MA, meta-analysis; CAP, community-acquired pneumonia; NS, not significant.

Can I Apply the Therapeutic Technology in My Practice? Can I expect a similar benefit in my clinical setting? Although the efficacy of new technologies such as NPPV is established in RCTs, their effectiveness outside of the RCT setting is uncertain.11,54 In one retrospective review of 75 ARF patients at a community hospital ICU receiving NPPV, mortality rates were greater than those reported in RCTs.54 In this study, the endotracheal intubation rate was 37% (28 of 75), with a mortality rate of 65% (18 of 28) in those who failed NPPV. However, 15 of the 18 patients who died did not wish further resuscitation if BiPAP failed. In another utilization at a tertiary care teaching hospital,11 the intubation and mortality rates in patients treated with NPPV were higher than those reported in RCTs, with a mortality rate of 25% (3 of 12) for the COPD population compared with 10% (31 of 319) in the meta-analysis of the literature12). Although the reasons for these differences between RCTs and real-world setting reviews likely are multifactorial, they do provide a cautionary note when considering the use of NPPV outside of the clinical trial setting.

When considering whether the use of a therapeutic technology is applicable to one’s own clinical setting, it is important to take into account other factors that may influence the successful application of the technology. Factors to consider include the following: patient factors (similarity to the population included in the RCTs); clinician factors (training and experience of the clinician); and environmental factors (location, monitoring capabilities). Although these factors are important to consider, they often are difficult to assess in a rigorous manner. How technology is implemented, and by whom, is as important as whether it is implemented. Ultimately, the effectiveness of any technology must be assessed in the specific setting in which it is applied. This can be accomplished by site-specific utilization reviews of the technology after it has been implemented in your ICU, incorporating the factors listed earlier. Were clinically important outcomes considered? The outcomes of the RCTs on the use of NPPV for ARF previously discussed used clinically important outcomes, including ETI rate, ICU and hospital length of stay, and ICU and hospital mortality. Some studies did consider physiologic out-

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comes (improvement in arterial blood gases) and resources (nurse and respiratory therapist [RT] time in the application of NPPV).39 Are the outcomes of the therapeutic technology dependent on guidelines, protocols, cardiopulmonary monitoring, or the operator? In the complex environment of the ICU, where intensivists are required to evaluate extensive clinical data and perform multiple tasks, protocols and guidelines are strategies that can ensure timely implementation of evidence, avoid delays in care, and facilitate a more standardized and efficient administration of care for critically ill patients.55,56 A systematic review of weaning from invasive positive pressure ventilation (IPPV)56 showed that protocols increase success of weaning from mechanical ventilation, thereby reducing the duration of mechanical ventilation. A single study has assessed the efficacy of NPPV in patients with COPD exacerbations on a specialized respiratory ward,27 and showed that NPPV can be effective in this setting of a nurse-driven protocolized implementation of NPPV. Another study evaluated the effect of implementation of a clinical practice guideline on ETI and mortality in patients placed on NPPV for ARF caused by COPD and congestive heart failure exacerbations in a tertiary care center.57 Although this group showed that a clinical practice guideline could improve the processes of care (increased transfer to and management of patients in the ICU, improved cardiopulmonary monitoring, and increased consultation by the pulmonary service), there was no specific reduction in ETI rate, or ICU or hospital mortality with guideline implementation in this before-after nonrandomized study.57 Until a large RCT is performed, however, it remains uncertain whether the use of practice guidelines of NPPV for ARF improve morbidity and mortality outside of the controlled clinical trial setting. The majority of RCTs of NPPV for patients with ARF performed to date have been limited to settings that provide cardiopulmonary monitoring. An examination of the efficacy of NPPV on a respiratory ward27 showed that NPPV in patients with ARF can be implemented successfully outside of a monitored setting. There have been no controlled clinical trials in NPPV that have assessed the effect of operator experience on patient outcome. With higher rates of ETI and mortality in studies de-

SINUFF AND COOK

scribing the use of NPPV on patient outcomes outside the conduct of RCTs without cardiopulmonary monitoring11,54 and variability in operator experience,11 it is possible that the effectiveness of this technology may, in fact, be partly dependent on cardiopulmonary monitoring of the patient on NPPV, and the experience of the operator. Has the Health Resource Utilization of the Technology Been Evaluated Adequately? The high cost of critical care medicine mandates critical care consultants to consider cost-effective delivery of this care for our patients. Critical care practitioners have a responsibility to consider the use of cost-effective interventions now, not just in the future. Determining cost effectiveness is a crucial but challenging aspect of HTA. The acquisition of any new technology involves opportunity costs and related benefits.58 However, maintaining technology currently in use also has opportunity costs. The consideration of costs of care takes into account both human and financial costs of health care delivery. There are 2 published studies evaluating the personnel time required to implement NPPV. Kramer et al39 examined the time spent by nurses and RTs during the first 16 hours of use of NPPV in their RCT of NPPV for COPD patients with ARF in the ED. During the first 8 hours of NPPV implementation, RTs spent more time with patients randomized to NPPV compared with the standard therapy group. Nurses spent approximately the same amount of time delivering care in both NPPV and control groups throughout the 16-hour time segment evaluated. An analysis of 10 consecutive patients with COPD exacerbations requiring NPPV compared with 6 patients intubated and mechanically ventilated after failing a trial of NPPV59 showed that the total clinician, RT, and nursing time during the first 48 hours of ventilation did not differ between NPPV and IPPV. There are several potential types of economic evaluations that could be performed to determine the efficiency of a technology. These evaluations may be considered under 2 general categories of partial and full economic evaluations.60 Partial evaluations consider only a cost analysis such as that performed by Nava et al59 for NPPV further described later. A full economic evaluation consists of “the comparative analysis of alternative courses of action in terms of both their costs and

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consequences,” and includes cost-minimization, costeffectiveness, cost-utility, and cost-benefit analyses.60 Two studies have evaluated the costs incurred during the use of NPPV in the context of an observational study59 and a full cost-effectiveness analysis61 in patients with severe COPD exacerbations. In the observational study, Nava et al59 found no difference in the costs associated with the use of NPPV compared with IPPV in a similar cohort of patients followed-up prospectively in their ICU. The daily cost of NPPV was similar in personnel costs, chest radiograph, pharmacy, supplies, laboratory, and indirect costs associated with the patients’ ICU care. The second study was a cost-effectiveness analysis to determine whether the use of NPPV in patients with severe COPD exacerbations reduced both ETI and mortality and hospital costs (sometimes referred to as a dominant scenario).61 These investigators performed a full sensitivity analysis using outcomes from a database of patients in 3 ICUs in Ontario. The results of the analysis showed a cost savings of $3,244 per patient admission with the use of NPPV compared with standard therapy (1996 Canadian dollars) for patients with ARF caused by COPD exacerbations. This was owing to lower rates of ventilator-associated pneumonia. Although the estimated cost savings were lower after sensitivity analysis, the net cost benefit for the use of NPPV remained. This thorough cost-effectiveness analysis substantiates the fact that NPPV reduces the rates of ETI and mortality at a significant cost savings for the hospital for patients with severe COPD exacerbations, based on Canadian costs at the time of the analysis. CLINICAL RESOLUTION

Thinking about your 2 patients, you confirm that the use of NPPV for patients with ARF caused by COPD exacerbation is warranted. You plan to continue with this treatment for your first patient. Because data on the use of a specific type of ventilator and interface are not available, you are uncertain as to which specific devices to use. You acknowledge less convincing evidence about the

benefit of NPPV for other subgroups, such as nonCOPD patients with acute hypoxemic, nonhypercarbic respiratory failure, patients receiving NPPV as a weaning alternative to IPPV, and patients with postextubation respiratory distress or failure. You plan to intubate your second patient. You reflect that these approaches are consistent with the expert recommendations from the recent consensus conference62 and state-of-the-art review.63 Finally, you note that use of NPPV for ARF may be cost effective,61 providing it is available and can be administered safely. CONCLUSIONS

In conclusion, the evidence to date is supportive of the use of NPPV in patients with ARF caused by exacerbations of COPD. No clear benefit has been shown in patients with acute nonhypercarbic, hypoxemic respiratory failure, although there are accumulating studies that show that NPPV may be efficacious in some of these patients. The success of NPPV technology also is dependent on operator education and experience. The cost effectiveness of NPPV has not been evaluated adequately except for use in patients with ARF caused by COPD. Unaddressed issues remain including determining: (1) the role of NPPV in patients with acute nonhypercarbic, hypoxemic respiratory failure, (2) the most responsive COPD population in terms of severity of exacerbations, (3) the best interface in the acute phases of ARF, and (4) the optimal ventilator to use for NPPV. New and improved therapeutic technologies, especially in the field of mechanical ventilation, will continue to be introduced to the critical care arena over the next decade. Important decisions regarding the acquisition of these devices will have to be made in light of shrinking ICU and hospital budgets. Critical appraisal of the literature using a simple HTA framework can help the intensivist and other members of the ICU team make important decisions regarding the acquisition of new technologies and the evaluation of current technologies. Given the economic realities of today’s and tomorrow’s health care systems, careful evaluation of health technologies will be an ongoing priority.64

REFERENCES 1. Multz AS, Chalfin DG, Samson IM, et al: A “closed” medical intensive care unit improves resource utilization when compared to an “open” MICU. Am J Respir Crit Care Med 157:1468-1473, 1998

2. Angus DC, Kelley MA, Schmitz RJ, et al: Committee on manpower for Pulmonary and Critical Care Societies caring for the critically ill patient. Current and projected ICU requirements for care of the critically ill and patients with pulmonary dis-

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eases: Can we meet the requirements of an aging population. JAMA 84:2762-2770, 2000 3. Sibbald WJ, Inman KJ: Problems in assessing technology of critical care medicine. Int J Technol Assess Health Care 8:419-443, 1992 4. Cook DJ, Sibbald WJ: The promise and the paradox of technology in the intensive care unit. CMAJ 161:1118-1119, 1999 5. Connors AF, Speroff T, Dawson NV, et al for the SUPPORT Investigators: The effect of right heart catheterization in the initial care of critically ill patients. JAMA 276:889-897, 1996 6. Ranieri VM, Suter PM, Tortorella C, et al: Effect of mechanical ventilation on pulmonary and systemic release of inflammatory mediators in patients with acute respiratory distress syndrome: A randomized controlled trial. JAMA 282:5461, 1999 7. Slutsky AS, Tremblay LN: Multiple system organ failure: Is mechanical ventilation a contributing factor? Am J Respir Crit Care Med 157:1721-1725, 1998 8. American Thoracic Society: International consensus conference in intensive care medicine: Ventilator-associated lung injury in ARDS. Am J Respir Crit Care Med 160:2118-2124, 1999 9. Power EJ, Tunis SR, Wagner JL: Technology assessment and public health. Annu Rev Public Health 15:561-579, 1994 10. Cook DJ, Sibbald WJ, Vincent JL, et al: Evidence based critical care medicine; what is it and what can it do for us? Evidence Based Medicine in Critical Care Group. Crit Care Med 24:334-337, 1996 11. Sinuff T, Cook DJ, Randall J, et al: Noninvasive positive pressure ventilation for acute respiratory failure: A utilization review in a teaching hospital. CMAJ 163:969-973, 2000 12. Peter JV, Moran JL, Phillips-Hughes J, et al: Noninvasive ventilation in acute respiratory failure–a meta-analysis update. Crit Care Med 30:555-562, 2002 13. Mulrow CD: The medical review article: State of the science. Ann Intern Med 106:485-488, 1987 14. Mulrow CD: Rationale for systematic reviews, in Chalmers I, Altman DG (eds): Systematic reviews. London, British Medical Journal Books, 1995, pp 1-8 15. Cook DJ, Mulrow CD, Haynes RB: Systematic reviews: Synthesis of best evidence for clinical decisions. Ann Intern Med 126:376-380, 1997 16. Cook DJ, Sackett DL, Spitzer WO: Methodologic guidelines for systematic reviews of randomized controlled trials in health care from the postdam consultation on meta-analysis. J Clin Epidemiol 48:167-171, 1995 17. Guyatt GH, Sackett DL, Cook DJ: How to use an article about therapy or prevention. A. Are the results of the study valid? Evidence-Based Medicine Working Group. JAMA 270: 2598-2601, 1993 18. Guyatt GH, Sackett DL, Cook DJ: How to use an article about therapy or prevention. B. What are the results and will they help me in caring for my patients? Evidence-Based Medicine Working Group. JAMA 271:59-63, 1994 19. Guyatt GH, Tugwell PX, Feeny DH, et al: A framework for clinical evaluation of diagnostic technologies. CMAJ 134: 587-594, 1986 20. Cook DJ, Brun-Buisson, Guyatt GH, et al: Evaluation of new diagnostic technologies: Bronchoalveolar lavage and the

SINUFF AND COOK

diagnosis of ventilator-associated pneumonia. Crit Care Med 22:1314-1322, 1994 21. Keenan SP, Guyatt GH, Sibbald WJ, et al: How to use articles about diagnostic technology: Gastric tonometry. Crit Care Med 27:1726-1731, 1999 22. Khilnani GC, Saikia N, Sharma SK, et al: Efficacy of non-invasive positive pressure ventilation for management of COPD with acute or acute on chronic respiratory failure: A randomized controlled trial. Am J Respir Crit Care 165:A387, 2002 23. Auriant I, Jallot A, Herve P, et al: A comparison of noninvasive positive pressure ventilation and conventional therapy in patients with acute hypoxemic respiratory failure following lung resection. Am J Respir Crit Care 163:A248, 2001 24. Ferrer M, Esquinas A, Leon M, et al: Noninvasive ventilation in severe hypoxemic acute respiratory failure. A randomized clinical trial. Am J Respir Crit Care 160:A250, 2000 25. Keenan SP, Powers C, McCormack DG: Noninvasive ventilation in milder COPD exacerbations: An RCT. Am J Respir Crit Care 163:A250, 2001 26. Hilbert G, Gruson D, Vargas F, et al: Noninvasive ventilation in immunosuppressed patients with pulmonary infiltrates, fever, and acute respiratory failure. N Engl J Med 344: 481-487, 2001 27. Plant PK, Owen JL, Elliott MW: Early use of noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: A multicentre randomised controlled trial. Lancet 355:1931-1935, 2000 28. Martin TJ, Hovis JD, Costantino JP, et al: A randomized, prospective evaluation of noninvasive ventilation for acute respiratory failure. Am J Respir Crit Care Med 161:807-813, 2000 29. Antonelli M, Conti G, Bufi M, et al: Noninvasive ventilation for treatment of acute respiratory failure in patients undergoing solid organ transplantation: A randomized trial. JAMA 283:235-241, 2000 30. Lapinsky SE, Aubin M: Randomized trial of noninvasive ventilation in acute respiratory failure—factors affecting mortality. Am J Respir Crit Care 159:A14, 1999 31. Confalonieri M, Potena A, Carbone G, et al: Acute respiratory failure in patients with severe community-acquired pneumonia. A prospective randomized evaluation of noninvasive ventilation. Am J Respir Crit Care Med 160:1585-1591, 1999 32. Celikel T, Sungur M, Ceyhan B, et al: Comparison of noninvasive positive pressure ventilation with standard medical therapy in hypercapnic acute respiratory failure. Chest 114: 1636-1642, 1998 33. Avdeev SN, Tret’iakov AV, Grigor’iants RA, et al: [Study of the use of noninvasive ventilation of the lungs in acute respiratory insufficiency due exacerbation of chronic obstructive pulmonary disease]. Anesteziol Reanimatol 3:45-51, 1998 34. Wood KA, Lewis L, Von Harz B, et al: The use of noninvasive positive pressure ventilation in the emergency department: Results of a randomized clinical trial. Chest 113: 1339-1346, 1998 35. Angus RM, Ahmed AA, Fenwick LJ, et al: Comparison of the acute effects on gas exchange of nasal ventilation and doxapram in exacerbations of chronic obstructive pulmonary

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disease [published erratum appears in Thorax 52:204, 1997]. Thorax 51:1048-1050, 1996 36. Barbe F, Togores B, Rubi M, et al: Noninvasive ventilatory support does not facilitate recovery from acute respiratory failure in chronic obstructive pulmonary disease. Eur Respir J 9:1240-1245, 1996 37. Wysocki M, Tric L, Wolff MA, et al: Noninvasive pressure support ventilation in patients with acute respiratory failure. A randomized comparison with conventional therapy. Chest 107:761-768, 1995 38. Brochard L, Mancebo J, Wysocki M, et al: Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease. N Engl J Med 333:817-822, 1995 39. Kramer N, Meyer TJ, Meharg J, et al: Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med 151:17991806, 1995 40. Bott J, Carroll MP, Conway JH, et al: Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease. Lancet 341:15551557, 1993 41. Daskalopoulou E, Tsara V, Fekete K, et al: Treatment of acute respiratory failure in COPD patients with positive airway pressure via nasal mask (NPPV). Chest 103:271A, 1993 42. Bardi G, Pierotello R, Desideri M, et al: Nasal ventilation in COPD exacerbations: Early and late results of a prospective, controlled study. Eur Respir J 15:98-104, 2000 43. Nava S, Ambrosino N, Clini E, et al: Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease. A randomized, controlled trial. Ann Intern Med 128:721-728, 1998 44. Girault C, Daudenthun I, Chevron V, et al: Noninvasive ventilation as a systematic extubation and weaning technique in acute-on-chronic respiratory failure: A prospective, randomized controlled study. Am J Respir Crit Care Med 160:86-92, 1999 45. Ferrer M, Arancibia F, Esquinas A, et al: Noninvasive ventilation for persistent weaning failure. Am J Respir Crit Care 161:A262, 2000 46. Hill NS, Lin D, Levy M, et al: Noninvasive positive pressure ventilation to facilitate extubation after acute respiratory failure: A feasibility study. Am J Respir Crit Care 161: A263, 2000 47. Wu CP, Lin HI, Cheng CH: Noninvasive ventilation can not decrease the extubation failure rate after 2-hour T-piece trial. Am J Respir Crit Care 161:A556, 2000 48. Keenan SP, Powers C, McCormack DG, et al: Noninvasive positive pressure ventilation for post-extubation respiratory distress: A randomized controlled trial. JAMA 287:3238-3244, 2002 49. Rosinha SRPO, Lobo SMA, Sanches HS, et al: Noninvasive positive pressure ventilation can prevent reintubation after acute respiratory failure: Results of a randomized study. Am J Respir Crit Care 161:A262, 2000

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50. Hilbert G, Gruson D, Portel L, et al: Noninvasive pressure support ventilation in COPD patients with postextubation hypercapnic respiratory insufficiency. Eur Respir J 11:13491353, 1998 51. Gay PC, Hess DR, Hill NS: Noninvasive proportional assist ventilation for acute respiratory insufficiency: Comparison with pressure support ventilation. Am J Respir Crit Care Med 164:1606-1611, 2001 52. Wysocki M, Richard J-C, Meshaka P: Noninvasive proportional assist ventilation compared with noninvasive pressure support ventilation in hypercapnic acute respiratory failure. Crit Care Med 30:323-329, 2002 53. Navaseli P, Fanfulla F, Frgerio P, et al: Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure. Crit Care Med 28:1785-1790, 2000 54. Alsous F, Amoateng-Adjepong Y, Manthous CA: Noninvasive ventilation: Experience at a community teaching hospital. Intensive Care Med 25:458-463, 1999 55. Ibrahim EH, Kollef MH: Using protocols to improve the outcomes of mechanically ventilated patients. Focus on weaning and sedation. Crit Care Clin 17:989-1001, 2001 56. Ely EW, Meade MO, Haponik EF, et al: Mechanical ventilator weaning protocols driven by non-physician healthcare professionals: Evidence based clinical practice guidelines. Chest 120:454S-463S, 2001 57. Sinuff T, Cook D, Randall J, et al: Evaluation of a practice guideline on noninvasive positive pressure ventilation for acute respiratory failure. Chest (in press) 58. Sachdeva RC: Measuring the impact of new technology: An outcomes-based approach. Crit Care Med 29:N190-N195, 2001 59. Nava S, Evangelisti I, Rampulla C, et al: Human and financial costs of non-invasive mechanical ventilation in patients affected by COPD and acute respiratory failure. Chest 111:1631-1638, 1997 60. Drummond MF, O’Brien B, Stoddart GL, et al: Methods for the economic evaluation of health care programmes, 2nd ed. Oxford, Oxford University Press, 1997, pp 2-27 61. Keenan SP, Gregor J, Sibbald WJ, et al: Noninvasive positive pressure ventilation in the setting of severe, acute exacerbations of chronic obstructive pulmonary disease: More effective and less expensive. Crit Care Med 28:2094-2102, 2000 62. Evans TW, Albert RK, Angus DC, et al: International consensus conferences in intensive care medicine: Noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med 163:283-291, 2001 63. Mehta S, Hill NS: Noninvasive ventilation. Am J Respir Crit Care Med 163:540-577, 2001 64. Sibbald WJ, Eberhard JA, Inman KJ, et al: New technologies, critical care, and economic realities. Crit Care Med 21:1777-1780, 1993