CLUSTER HEADACHE - PULSE-RATE CHANGES EVOKED BY HYPEROXIA AND HYPOXIA

To test the influence of arterial O2 saturation (SaO2) on heart rate i n cluster headache, changes in pulse rate induced by hyperoxia and hyp oxia were monitored in 11 cluster headache patients (6 during cluster period, and 5 during remission). The results were compared with those obtained in 11 age and sex matched healthy individuals. The subjects w ere administered 5 min each of 100% O2 and 12% O2 in nitrogen in seque nce. The aim of the latter procedure was to reduce SaO2 to approximate ly 80%. Pulse rate was recorded every minute from a finger pulse oxime ter during the whole procedure. Cluster headache patients, in particul ar during the bout, had a slightly lower basal pulse rate than control s (P>0.5, Student's t-test). This tendency was maintained throughout t he test. Hyperoxia and hypoxia resulted in a marked, significant decre ase and increase, respectively, in pulse rate from baseline values wit hin each group. However, the difference between groups was not signifi cant at any stage. Cluster headache patients therefore seem to have th e same heart rate response to changes in SaO2 as healthy individuals. The marked heart rate changes which sometimes accompany cluster headac he are unlikely to be caused by SaO2 changes.