A Randomized, Dose-Finding Study of Sphenopalatine Ganglion Block With Bupivacaine for Emergency Department Patients...

To determine, when performing a sphenopalatine ganglion block (SPGB) for emergency department (ED) patients with headache, whether larger doses of bupivacaine result in greater rates of sustained headache relief than lower doses.

This was a randomized, 4-armed study conducted in 2 EDs. Eligible patients were those with a moderate or severe primary or secondary headache. We randomized patients to unilateral (UL) or bilateral (BL) transnasal SPGB with 0.5% bupivacaine and also to high dose (3 mL) or low dose (1 mL) bupivacaine. Thus, participants could have received 1 mL, 2 mL, 3 mL, or 6 mL of bupivacaine. No attempts were made to blind study participants or investigators. We did not use a sham procedure. We assessed pain using the descriptors severe, moderate, mild, or none. The primary outcome was sustained headache relief, defined as achieving a headache intensity of mild or none within 2 hours of medication administration and maintaining a level of mild or none for 48 hours after the procedure without the use of any rescue analgesic medications at any time during the 48 hours. The secondary outcome was the request to receive the same medication during a subsequent visit to the ED for headache. The minimum clinically important between-group difference was an absolute risk reduction of 15% to 20%.

In total, 2,494 patients were screened for eligibility, and 220 were randomized. Of the 2,494 patients, 1,612 (65%) refused participation because they preferred a route of administration other than nasal. Rates of sustained headache relief were as follows: 3 mL BL, 17/54 (31%); 3 mL UL, 15/44 (34%); 1 mL BL, 23/65 (35%); and 1 mL UL, 9/48 (19%). When compared to the 1 mL UL dose, neither the 3 mL BL (95% CI for difference of 13% -4% to 29%) nor the 3 mL UL dose (95% CI for difference of 15% -2% to 33%) resulted in more sustained relief. Rates of wish to receive again were 3 mL BL, 35/53 (66%); 3 mL UL, 26/ 44 (59%); 1 mL BL, 36/62 (58%); and 1 mL UL, 33/45 (73%). There were no statistically significant differences among the groups regarding wish to receive again. The intervention was generally well tolerated, with minor procedure-related adverse events reported in ≤10% of participants in each arm.

Among ED patients with headache treated with a SPGB, larger doses of bupivacaine do not result in more sustained headache relief than smaller doses.