Evidence-based Management of Patients with Respiratory Failure: An Introduction
A. Esteban, A. Anzueto, and D. Cook
“Success in science is defined as moving from failure to failure with undiminished enthusiasm”
Sir Winston Churchill Respiratory failure is a complex disease process whereby the underlying disease and therapeutic measures interact. The patient’s outcome is determined by a variety of factors including how we use therapeutic maneuvers such as mechanical ventilation for prevention of complications, e.g., ventilator-associated pneumo- nia. In this book, a wide range of topics related to respiratory failure are summa- rized. The objective of this publication is to critically review and discuss the clinical evidence available for the diagnosis and management of patients with respiratory failure. Presentations in this book are a summary of comprehensive and critical review of the literature with the ultimate objective of improving the clinical outcomes of patients with respiratory failure.
All the chapters in this book have followed a strict methodology for data search and criteria to identify the appropriate publications. The authors searched several bibliographic databases to identify relevant studies, including but not limited to MEDLINE, EMBASE, HEALTHStar, CINAHL, The Cochrane Controlled Trials Registry, and The Cochrane Data Base of Systematic Reviews. Use of EMBASE maximized the possibility of identifying relevant European publications. Other literature sources such as reference lists and personal files were also included.
The target of these reviews was to identify all pertinent information related to adult patients who are mechanically ventilated either via endotracheal tube, tra- cheostomy, or face mask. Thus invasive and non-invasive ventilation studies were included. We also identified studies that described complications arising from the use of mechanical ventilation which resulted in significant morbidity or mortality.
We excluded clinical studies in pediatric and/or neonatal patients. Clinical settings relevant to these reviews were intensive care units (ICUs), intermediate care units, step-down units and post-anesthetic recovery rooms. We excluded studies related to home ventilation and chronic ventilator facilities.
In this book, each chapter describes the specific design of the clinical studies including patient’s clinical characteristics, methods, and results. The methodologi- cal features related to each topic are also highlighted. The authors classified the studies reviewed using a level of evidence that was based on previous described classifications. The levels of evidence were based on the studies that have an
emphasis on preventive and therapeutic interventions. Thus, randomized control- led trials had a higher level than observational studies. However, due to the focus and strict entry criteria of many randomized trials, the authors accepted the premise that observational studies may be better suited than randomized studies to address issues such as prevalence, incidence, risk factors, prognosis, and mecha- nisms of a disease process. For example, one recent international observational study illustrated how factors present at baseline ( e.g., coma), factors related to patient management (e.g., ventilator plateau pressures), and factors that develop during the course of mechanical ventilation (e.g., oxygenation ratio) are all predic- tive of mortality among patients undergoing mechanical ventilation [1].
The authors used the following evidence grading system:
Level A evidence: randomized trials, systematic reviews, and/or meta-analyses of randomized trials that had a clearly defined methodology, large sample size, and yielded consistent results if more than one trial existed.
Level B evidence: randomized trials, systematic reviews and/or meta-analyses of randomized trials that are of a lower quality, smaller sample size, and yielded inconsistent results if more than one trial existed.
Level C evidence: controlled observational studies, uncontrolled observational studies, utilization reviews, surveys of stated clinical practice, and/or physiological studies.
Level D evidence: clinical judgment, expert opinion or consensus, and/or case reports.
The authors indicate clinical evidence and separate this rating from clinical inter- pretation. We did not used a quantitative scoring system to assess the validity of the literature search due to the diversity of the objectives, designs, clinical popula- tions, interventions, predictors of outcome and multiple interventions identified.
Each chapter also includes 3-5 conclusions that summarize the evidence available, and the authors provide their insight into future research directions.
Several prior publications have focused on critical care to improve our skills at searching and appraising clinical research, including Evidence Based Critical Care Medicine [2], systematic reviews of observational and experimental evidence lead- ing to Evidence Based Guidelines on Weaning from Mechanical Ventilation [3], and numerous workshops and symposia on evidence-based clinical practice at national and international meetings. We hope that this book will highlight the awareness of the extensive and still growing body of literature related to the care of patients with respiratory failure. Furthermore, in the future more practitioners will be aware of the ongoing preventive and therapeutic interventions tested in randomized control trials that will result in an improvement in the management of these patients [4].
Currently, we rely on observational studies such as utilization reviews [5, 6] to evaluate whether the best clinical care that has been determined in randomized trials are actually used in patient management. But, there is a growing body of evidence that this is not the case. There are several examples of the lack of 2 A. Esteban, A. Anzueto, and D. Cook
implementation of these studies: In nosocomial pneumonia the lack of utilization of strategies such as semirecumbency bed position [7]; in mechanical ventilation weaning, the lack of use of two hour spontaneous breathing trials to expedite safe weaning [6], and in the acute respiratory distress syndrome (ARDS) the lack of use of low tidal volume ventilation [8]. All these measures have been shown to improve patient outcome. The data suggest that there is a need to develop strategies to change clinician behavior, such as interactive education, frequent reminders, feedback information, and frequent re-evaluation to see if there is an improvement in the application of these measures [9].
In summary, this book on the Evidence Based Management of Patients with Respiratory Failure provides important information to improve patient outcome by clearly identifying the research evidence that we can apply in our clinical practice.
References
1. Esteban A, Anzueto A, Frutos F, et al (2002) Characteristics and outcomes in adult patients receiving mechanical ventilation: A 28 day international Study. JAMA 287:345-355
2. Cook DJ, Sibbald WJ, Vincent JL, Cerra FB, for the Evidence Based Medicine in Critical Care Group (1996) Evidence based critical care medicine: What is it and what can it do for us? Crit Care Med 24: 334-337
3. ACCP-SCCM-AARC Evidence based guidelines task force (2002) Evidence based guidelines for weaning and discontinuation of ventilatory support. Chest 120 (Suppl 6): 375S – 395S 4. Ferreira F, Vincent JL, Brun-Buisson C, Spruing C, Sibbald W, Cook DJ (2001) Doctors
perception of the effects of interventions tested in prospective, randomized, controlled, clinical trials: results of a survey of ICU physicians, Intensive Care Med 27:548-554
5. Esteban A, Anzueto A, Alia I, et al (2000) How is mechanical ventilation employed in the intensive care unit ? Am J Respir Crit Care Med 161:1450-1458
6. Soo GW, Park L (2002) Variations in the management of weaning parameters: a survey of respiratory therapist. Chest 121:1947-1955
7. Cook DJ, Meade M, Hand L, McMullin J (2002) Semirecumbency for pneumonia prevention:
A developmental model for changing clinical behavior. Crit Care Med 20:1472 – 1427 8. Rubenfeld GD, Caldwell E, Hudson L (2001) Publication of study results dos not increase use
of lung protection ventilation in patients with acute lung injury. Am J Respir Crit Care Med 163:A295 (abst)
9. Bero LA, Grilli R, Grimsahw JM (1998) Closing the gap between research and practice: An overview of systematic reviews of interventions to promoter the implementation of research findings. Br Med J 317:465-468
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