The analgesic effect of oxygen during percutaneous coronary intervention (the OXYPAIN Trial).
INTRODUCTION
Oxygen is considered to have analgesic effects, but the evidence is weak. Oxygen may be harmful to the ischemic myocardium. The aim was to investigate the analgesic effect of oxygen during percutaneous coronary intervention (PCI) and to evaluate cardiac injury.


MATERIAL AND METHODS
The OXYPAIN was a phase II randomized trial with a double blind design. 305 patients were randomized to receive oxygen or atmospheric air during PCI. The patients were asked to score chest pain by the Visual-Analog Scale (VAS). The use of analgesic agents and troponin-t was measured.


RESULTS
There was no significant difference in pain between the groups: oxygen: 2.0, [2.0-4.0], air: 2.0, [2.0-5.0] (median, interquartile range: 25-75%, P = 0.12). The median difference in score of VAS was [95% CI]: 0, [0-1.0]. The oxygen group received 0.44 ± 0.11 mg of morphine versus 0.46 ± 0.13, P = n.s. The peak value of troponin-t post-PCI was 38, [11-352] nmol/ml in the oxygen group and 61, [16-241] for patients treated with air, P = 0.46.


CONCLUSIONS
The use of oxygen during PCI did not demonstrate any analgesic effect. There was no difference in myocardial injury measured with troponin-t or in the morphine dose. Our results do not support routine use of oxygen. (NCT01413841.).