Mechanism of bronchodilator effect in chronic airflow limitation.

OBJECTIVE: To examine the mechanisms through which two bronchodilators (theophylline and salbutamol) influence dyspnea during daily activities. METHODS: Twenty-four patients with chronic airflow limitation participated in a multiple crossover, randomized, placebo-controlled trial. The effect of theophylline and salbutamol, alone or combined, on pulmonary function and dyspnea during daily activities was examined. Correlations of changes in forced expiratory volume in 1 second (FEV1) and maximum expiratory pressures (MIPs) (independent variables) and changes in dyspnea score during daily activities (dependent variable) were also examined. RESULTS: The two drugs proved to be beneficial the effects in general were additive rather than synergistic. The drugs improved the FEV1; theophylline significantly improved the MIPs. The correlation between the changes in FEV1 and those in dyspnea score, after adjustment for the changes in MIPs, was 0.55 (p less than 0.001). The correlation between the changes in MIPs and those in dyspnea score, after adjustment for the changes in FEV1, was 0.39 (p less than 0.001). CONCLUSIONS: Changes in airway calibre and in respiratory muscle strength play an independent and important role in dyspnea during daily activities in patients with chronic airflow limitation. Changes in airway calibre may be of greater importance.     

The influence of lung volume reduction surgery on exercise in patients with COPD.

Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment.     

Perioperative cardiac events in patients undergoing noncardiac surgery: a review of the magnitude of the problem, the pathophysiology of the events and methods to estimate and communicate risk

THIS IS THE FIRST OF 2 ARTICLES EVALUATING cardiac events in patients undergoing noncardiac surgery. In this article, we review the magnitude of the problem, the pathophysiology of these events, approaches to risk assessment and communication of risk. The number of patients undergoing noncardiac surgery worldwide is growing, and annually 500 000 to 900 000 of these patients experience perioperative cardiac death, nonfatal myocardial infarction (MI) or nonfatal cardiac arrest. Although the evidence is limited, a substantial proportion of fatal perioperative MIs may not share the same pathophysiology as nonoperative MIs. A clearer understanding of the pathophysiology is needed to direct future research evaluating prophylactic, acute and long-term interventions. Researchers have developed tools to facilitate the estimation of perioperative cardiac risk. Studies suggest that the Lee index is the most accurate generic perioperative cardiac risk index. The limitations of the studies evaluating the ability of noninvasive cardiac tests to predict perioperative cardiac risk reveals considerable uncertainty as to the role of these popular tests. Similarly, there is uncertainty as to the predictive accuracy of the American College of Cardiology / American Heart Association algorithm for cardiac risk assessment. Patients are likely to benefit from improved estimation and communication of cardiac risk because the majority of noncardiac surgeries are elective and accurate risk estimation is important to allow informed patient and physician decision-making.     

Factors affecting physicians' decisions on caring for an incompetent elderly patient: an international study.

OBJECTIVES: To determine what treatment decisions physicians will make when faced with a hypothetical incompetent elderly patient with life-threatening gastrointestinal bleeding and to examine the relative importance of physician characteristics and factors (legal and ethical concerns, hospital costs, level of dementia, patient's age, physician's religion, patient's wishes and family's wishes) in making those decisions. DESIGN: Survey. SETTING: Family practice, medical and geriatrics rounds in academic medical centres and community hospitals in seven countries. PARTICIPANTS: Physicians who regularly cared for incompetent elderly patients. MAIN OUTCOME MEASURES: A self-administered questionnaire describing the elderly patient. Respondents were asked to choose one of four levels of care and to identify the level of importance factors had in making that decision. Older physicians, those less concerned about litigation, those for whom the level of dementia was important and those for whom the patient's age was important were expected to give less aggressive care than the other physicians. MAIN RESULTS: Supportive care was chosen by 8.1% of the respondents, limited therapeutic care by 41.5%, maximum therapeutic care without admission to the intensive care unit (ICU) by 32.2% and maximum care with admission to the ICU by 18.2%. The patient's wishes were reported by 91.0% as being extremely or very important in choosing the treatment. Stepwise logistic regression analysis revealed that the following variables independently predicted the level of treatment: level of dementia, country of residence, duration of practice, legal concerns, patient's age and ethical concerns. These factors were significantly correlated with the physicians' treatment choices (p less than 0.05). CONCLUSIONS: The importance that the physicians placed on the level of dementia was the strongest predictor of the level of care that would be provided. A societal consensus on the influence of cognitive function on the appropriate level of care as well as training of physicians in ethical issues are required.     

Measuring health status in chronic airflow limitation

A health status instrument for use in clinical trials must be valid (measuring what it is supposed to measure) and responsive (able to detect clinically important change). Approaches to measuring health status in clinical trials include using a battery of instruments, a general instrument which provides a profile of the patient's health, an instrument that generates a health utility, or an instrument that focuses on the problems associated with a particular disease. Disease-specific instruments have been used in clinical trials in chronic airflow limitation (CAL). The Oxygen Cost Diagram is simple and easy to administer, but responsiveness and validity are unproven. The Transition Dyspnoea Index is valid and responsive, but is difficult to use in trials in which multiple measurements are desired. The Chronic Respiratory Disease Questionnaire has proved valid and responsive in controlled trials in CAL patients. Health status measures should be included in all clinical trials in CAL.     

The contribution of a non-invasive test to clinical care. The impact of echocardiography on diagnosis, management and patient anxiety

We prospectively studied the impact of echocardiography on a cardiologist's diagnosis and management plan and on patient anxiety for 300 consecutive referrals. There was an impact on diagnosis in 90% of patients. Most common was confirmation of diagnosis usually with the addition of information pertinent to management (81%); change of disease category or resolution of diagnostic doubt was uncommon (9%). The consultant cardiologist believed the heart to be normal in 48 patients who did not have any associated disease; none had any echocardiographic abnormality. The cardiologist reported increased diagnostic confidence in 74% of all patients but management changed in only 9%. One-third of all patients reported reduced anxiety when this was an important clinical issue but in less than half of them did the cardiologist consider that echocardiographic information was essential for reassurance. Anxiety was increased in 6%, and in 12% the anxiety response was inconsistent with the test result. The clinical contribution of the test report was most obvious for those patients (30%) in whom this data was required for (a) a decision concerning specific diagnostic or technical intervention (b) a change of management plan which implied obvious or likely health benefit (c) reassurance which was a clinically important issue. The magnitude of this contribution was related to the study indication. The value of echocardiography is obvious when assessing patients for invasive intervention or when proper treatment or adequate reassurance are impeded by diagnostic doubt. However, for many current indications, we need better definition of factors which predict a clinically useful result. In particular, when the aim is to rule-out disease, our results suggest that an expert cardiological opinion would often be more appropriate than an echocardiogram.