| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 1997;64:1583-1584
© 1997 The Society of Thoracic Surgeons
Divisions of General Medical Sciences and Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine and Barnes-Jewish Hospital, St. Louis, Missouri
Medical technologies, whether devices, medications, guidelines, or procedures, should be evaluated before we prescribe them as part of routine care. To evaluate any particular technology, we find it useful to address the technology on five broad levels: biologic plausibility, technical feasibility, intermediate outcomes, patient outcomes, and societal outcomes [1]. Although a good technology will stack up well against all five, many promising new ideas have problems at one or more of these levels.
In this issue of The Annals of Thoracic Surgery, Handy and colleagues [2] describe pneumoperitoneum as a treatment for pulmonary parenchymal air leaks associated with a pleural space after a lung volume reduction operation. How do we decide if this therapy is worthwhile? To begin to answer this question, we recommend considering all five areas for this technology.
Is the technology biologically plausible? Does it have a rationale in science? Can we imagine a reason for this technology to work? Pneumoperitoneum causes enlargement of the abdominal cavity, elevation of the diaphragm, and a subsequent decrease in size of the thoracic cavity [3]. With the decrease in size of the pleural space, the parietal and visceral pleura may become better apposed, allowing for faster closure of the air leak. Thus, there appears to be a biologic rationale for this therapy.
Is the technology technically feasible? If a technology cannot be delivered safely and effectively to the patient, it will never be useful. We know that pneumoperitoneum is feasible because it has been used successfully in the past as treatment for emphysema and tuberculosis [4]. Handy and colleagues [2] also demonstrated their ability to perform this procedure. Although the appropriateness of the procedure is not addressed at this level of assessment, the ability to safely and reliably deliver it to patients is important.
Does the technology achieve its physiologic and anatomic goals? Intermediate outcomes are the biologic, anatomic, physiologic, or clinical effects of the technology. For pneumoperitoneum, these effects are decreasing the size of the pleural space and stopping the air leak. (Successful elevation of the diaphragm could be defined as an intermediate outcome, but the more pertinent intermediate outcome would be cessation of the air leak.) Handy and colleagues [2] did an admirable job of showing an association between pneumoperitoneum therapy and improved intermediate outcomes in the 1 patient reported, although other factors such as chemical pleurodesis may have played a significant role as well. A larger experience would tell us how often the air leaks could be controlled under broader clinical circumstances.
However, demonstration of the achievement of intermediate outcomes such as resolution of an air leak does not necessarily lead to an improved patient outcome. For example, significant morbidity such as pain or air embolism may be associated with pneumoperitoneum therapy and overwhelm the intermediate benefits. How often does this happen?
Does the technology improve patient outcomes? The fourth level of assessment, patient outcomes, is the most important and most pertinent from the patient's viewpoint. It may also be the most important issue for the physician. Although Handy and colleagues [2] suggest that patient outcomes are improved, the literature does not yet provide strong evidence for improvement in morbidity, mortality, symptoms, functional status, quality of life, or satisfaction from pneumoperitoneum therapy. The new field of "outcomes research" takes its name from this level of technology assessment. Formal research methods are now available to reliably measure these once "soft" outcomes so that the impact of therapy on patients can be assessed.
Our enthusiasm for any technology that repairs the anatomy or physiology should be tempered by remembering the many technologies that succeeded at the intermediate level but failed miserably for the patient. For example, the Coronary Arrhythmia Suppression Trial [5] randomized patients with recent myocardial infarction to receive different antiarrhythmic agents, including encainide and flecainide, to treat premature ventricular contractions. The investigators hypothesized that suppression of premature ventricular contractions would reduce the triggers responsible for initiating a sustained ventricular tachyarrhythmia and thus reduce the incidence of sudden death. The occurrence of low-grade arrhythmias did decrease dramatically. However, the study was terminated prematurely because patients who were given encainide or flecainide had a greater mortality rate than those receiving placebo. The intermediate outcomes were not tightly linked to the more important patient outcomes. Only by studying patient outcomes did we learn about the inadequacies of our medical model.
How does the technology affect others? The fifth level of assessment, societal outcomes, has to do with the external effects of medical technologies. These include costs, length of stay in the hospital, and other consumption of shared resources. Ethical issues related to the application of a technology, as well as any pollution or adverse effects on the general population or health care workers, are also considered at this stage. Recent increases in attention to these issues have forced doctors to become acquainted with cost-effectiveness, accounting, economics, and health policy research. Although most of these issues (except perhaps cost and length of stay) may be negligible for pneumoperitoneum therapy, they have not yet been adequately addressed.
Handy and colleagues [2] propose that pneumoperitoneum and concomitant chemical pleural sclerosis are "important and effective tools... ." These investigators have nicely demonstrated the biologic plausibility and technical feasibility of pneumoperitoneum therapy. In addition, some intermediate outcomes such as a decrease in the size of the pleural space and cessation of the air leak have been demonstrated. However, this technology has not yet been fully assessed. A case report of anatomic and physiologic success is an optimistic starting point, but it is not convincing evidence that we know best how to take care of these air leaks. Detailed reporting of the intermediate, patient-level, and societal outcomes (perhaps with a carefully chosen control group) would not only allow us to assess the usefulness of this technique, but would systematically point out its weaknesses. This information could be critical for designing improved surgical approaches.
The lack of a thorough analysis of pneumoperitoneum therapy at all five levels of technology assessment does not say that this therapy should be abandoned, but it does suggest that it should undergo further rigorous scientific evaluation before it is applied as an accepted and successful technology.
Acknowledgments
Supported in part by an award from the Norman P. Knowlton, Jr, MD, Incentive for Excellence Fund of Barnes-Jewish Hospital.
Footnotes
Address reprint requests to Dr Yusen, Washington University School of Medicine, Box 8052, 660 S Euclid, St. Louis, MO 63110 (e-mail: yusen{at}im.wustl.edu).
References
Related Article
This article has been cited by other articles:
|
|
 |
|
  R. J. Cerfolio, W. L. Holman, and C. R. Katholi Pneumoperitoneum after concomitant resection of the right middle and lower lobes (bilobectomy) Ann. Thorac. Surg., September 1, 2000; 70(3): 942 - 946. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Carbognani, L. Spaggiari, P. Solli, and M. Rusca Pneumoperitoneum for prolonged air leaks after lower lobectomies Ann. Thorac. Surg., August 1, 1998; 66(2): 604 - 605. [Full Text] [PDF]
|
|
|
|
|
|
J. A. Smith Air leaks and pleural spaces after lung volume reduction Ann. Thorac. Surg., August 1, 1998; 66(2): 610 - 610. [Full Text] [PDF]
|
|
|
|
|
|
R. D. Yusen and B. Littenberg Reply Ann. Thorac. Surg., August 1, 1998; 66(2): 610 - 611. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
