Episodic Breathlessness in Patients with Advanced Cancer: Characteristics and Management

The aim of this review is to present the way in which episodic breathlessness (EB) has been recognized over the years, with regard to definition, characteristics, and management of these acute episodes that have serious consequences for patients. EB is characterized by a sudden increase in intensity of dyspnea over a short duration of time, leading to high levels of anxiety. A significant aggravation of dyspnea may occur in patients with a background of dyspnea or intermittently even without basal breathlessness. Often, known precipitating factors may trigger EB. Flares of breathlessness are accompanied by degrees of psychological distress, although it is unclear whether psychological factors may precede or be induced by EB. In any case, there is a reinforcing circuit. The duration of EB ranges from 10–30 min. Given the specific temporal pattern, requiring rapid intervention, substances with a short onset of action are suitable to overlap this phenomenon. Short-onset opioids could provide a clinical effect overlapping the onset and duration of an episode, resembling what has been largely reported for breakthrough pain. Although data are still insufficient to suggest specific recommendations, strategies such as avoiding exertion, pacing or using devices, or keeping calm have been described. Few controlled studies have investigated the effects of different formulations of opioids. Some data were gathered from studies assessing the pre-emptive use of rapid onset opioids, such as transmucosal preparations of fentanyl, followed by a provocative test, while other studies attempted to reproduce real-life conditions, given as needed. All these trials were insufficiently powered to address the efficacy of fentanyl products over oral morphine or placebo, reflecting the difficulties in patient recruiting and finalizing the studies. Strategies to prevent the occurrence of EB should be taken into consideration, including optimization of the condition of persistent dyspnea or treating psychologic or environmental causes.