Background Dyspnoea is a complex experience of the body and the mind. Whereas the effects of opioids on dyspnoea in advanced disease have been the focus of studies for management of dyspnoea in palliative medicine, the role of oxygen is still unclear. The effects of symptomatic oxygen and opioid treatment on ventilation and palliation of dyspnoea in hypoxic (H) and non-hypoxic (NH) palliative care patients were assessed and compared. Methods In a prospective, non-randomised study, 46 patients with mild to severe dyspnoea were included. Transcutaneous measurement (earlobe sensor) of carbon dioxide partial pressure (tcpaCO 2 ), pulse oximetry oxygen saturation (SaO 2 ) and pulse frequency (PF) were monitored with SenTec digital monitor. Compared was: baseline data of the continuously documented respiratory parameters for about 15 min in patients breathing room air at admission, 60 min during nasal O 2 insufflation, and 30, 90 and 120 min after the first opioid application and without O 2 insufflation.
Results Whereas opioid application resulted in a significant decrease in the intensity of dyspnoea and respiratory rate, during the nasal O 2 insufflation (4 l/min), there was no significant decrease in the intensity of dyspnoea neither in H (P=0.564) nor in NH (P=0.096) patients. There was no evidence of a significant correlation between the intensity of dyspnoea and oxygen saturation. The Spearman rank correlation in NH patients was -0.080 (P=0.686) and in H patients P=0.296 (P=0.233). No significant differences between the groups of hypoxic and non-hypoxic patients with regard to tcpaCO 2 increase (P=0.075 NH; P=0.346 H) or SaO 2 decrease after opioid application (P=0.077) were found. Conclusions In this study, opioids worked significantly better than oxygen in reducing the intensity of dyspnoea even in hypoxic patients. There was no correlation between intensity of dyspnoea and oxygen saturation in H and NH patients. Oxygen should be seen as a pharmacological agent and not be given based on intuitive assumption of benefit.