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The available clinical information to date does not support the hypothesis that tissue oxygen debt is the primary cause of the wasting process in the chronic obstructive pulmonary disease (COPD) patient population. However, this should not deter the ‘believers’ of the hypothesis from further investigation. The information outlined above supports the need for reconsideration of this clinical problem. Tissue oxygen requirements and utilization is a complex interplay of multiple variables. Likewise, the assessment of nutritional status in the setting of oxygen therapy is complicated by shifts in body fluid compartments independent of changes in the fat-free mass (FFM). Utilization of newer techniques will be required to resolve the contribution of low tissue oxygenation to the wasting process. The continued development of noninvasive methods for the assessment of tissue metabolism, cardiac function, and tissue energy requirements will allow investigators to further clarify the relationship between tissue oxygenation and metabolism in patients with COPD. Clinical trials designed to examine this issue must recognize the multiple effects of oxygen on all aspects of nutrient utilization, including caloric intake, needs, and tissue delivery. Failure to address all aspects of this system will lead to continued debate regarding the etiology of weight loss in the COPD patient population.

There is no evidence that erroneous or biased prognostic estimates affect intensive care unit treatment choices. Neither the principle of maximizing expected utility nor the Rule of Rescue appear to affect these decisions systematically, but practice style does.

Recent regulations require commercial US aircraft to carry an enhanced medical kit. We reviewed kit use on United Airlines during the initial year of the regulations. We also surveyed passengers who became ill during flight and health care providers who used the new kit. The medical kit was used 362 times on 361 flights (once in every 1900 flights or one use for every 150,000 air travelers). Health care providers indicated that the kit was useful in more than 80% of emergencies and was occasionally lifesaving. In the emergencies in which the kit was used, 70% fell into one of seven major diagnostic groupings, including syncope/near syncope (29%), cardiac/chest pain (16%), asthma/lung disease/shortness of breath (10%), and allergic reactions (5%). With 450 million domestic air travelers per year, we would expect 3000 in-flight medical emergencies annually, and conclude that the enhanced medical kit is beneficial and propose that its effectiveness would be improved by the addition of a bronchodilator for inhalation.