Tiotropium: A Bronchodilator for Chronic Obstructive Pulmonary Disease

Optimising mechanical ventilation through model-based methods and automation

Mechanical ventilation (MV) is a core life-support therapy for patients suffering from respiratory failure or acute respiratory distress syndrome (ARDS). Respiratory failure is a secondary outcome of a range of injuries and diseases, and results in almost half of all intensive care unit (ICU) patients receiving some form of MV. Funding the increasing demand for ICU is a major issue and MV, in particular, can double the cost per day due to significant patient variability, over-sedation, and the large amount of clinician time required for patient management. Reducing cost in this area requires both a decrease in the average duration of MV by improving care, and a reduction in clinical workload. Both could be achieved by safely automating all or part of MV care via model-based dynamic systems modelling and control methods are ideally suited to address these problems. This paper presents common lung models, and provides a vision for a more automated future and explores predictive capacity of some current models. This vision includes the use of model-based methods to gain real-time insight to patient condition, improve safety through the forward prediction of outcomes to changes in MV, and develop virtual patients for in-silico design and testing of clinical protocols. Finally, the use of dynamic systems models and system identification to guide therapy for improved personalised control of oxygenation and MV therapy in the ICU will be considered. Such methods are a major part of the future of medicine, which includes greater personalisation and predictive capacity to both optimise care and reduce costs. This review thus presents the state of the art in how dynamic systems and control methods can be applied to transform this core area of ICU medicine.

Using cost-effectiveness analysis to sharpen formulary decision-making: the example of tiotropium at the Veterans Affairs health care system

OBJECTIVE

To identify a cost-saving subset of criteria for the use of tiotropium at a Veterans Affairs Medical Center based on a cost-effectiveness analysis with ipratropium as the comparator.

METHODS

Retrospective analysis of electronic medical records for the calendar year 2004 was conducted. The sample was drawn from a population at the Baltimore Veterans Affairs Medical Center that had a confirmed diagnosis of chronic obstructive pulmonary disease (COPD) and had filled prescriptions for ipratropium. The tiotropium sample was based on a modeled cohort of COPD patients who had received tiotropium. The analysis was conducted from the perspective of the Veterans Affairs Health Care System. The outcome was the incremental cost-effectiveness of tiotropium versus ipratropium.

RESULTS

The incremental cost-effectiveness ratio (ICER) was $2360 per avoided exacerbation. Tiotropium cost-effectiveness increased with COPD severity and was cost-saving in patients with very severe disease (ICER = $-1818) and in patients with a previous COPD-related hospitalization (ICER = $-4472). The ICER was most sensitive to the relative effectiveness and price of tiotropium. Results identified the levels of treatment effectiveness and price beyond which tiotropium would become cost-saving relative to ipratropium.

CONCLUSIONS

The results support the existing Veterans Affairs practice of offering tiotropium to patients with COPD-related hospitalizations. Periodic review of the effectiveness data to determine whether tiotropium would be cost-saving in patients with very severe COPD is suggested. Cost-effectiveness analyses that identify practical criteria-for-use should become an integral part of the formulary process.

Single dose of inhaled procaterol has a prolonged effect on exercise performance of patients with COPD

The aim of this study was to examine the prolonged effect of procaterol, a short-acting bronchodilator, on lung function and exercise performance in patients with moderate to severe COPD. A randomized crossover trial was conducted. We recruited 19 patients with COPD aged 71.6+/-5.5 years. Patients were randomly assigned to receive either 20 mug inhaled procaterol followed by no-treatment or no-treatment followed by 20 mug inhaled procaterol separated by a washout period of 3+/-2 days. Lung function and exercise performance, using the incremental shuttle walking test (ISWT), were measured at baseline and 4 hours after receiving each treatment. Baseline forced expiratory volume in 1 second (FEV(1)) was 38.5%+/-17% predicted. There were no significant changes in FEV(1) following inhaled procaterol. However, walking distance increased by 294+/-113 meters at baseline to 331+/-119 meters after inhaled procaterol (p<0.001). These findings support the beneficial effects of inhaled procaterol on exercise performance in the absence of any change in FEV(1) when measured at 4 hours following inhalation in subjects with moderate to severe COPD. The inhaled procaterol may be useful for enhancing the effects of exercise training in patients with COPD.