CENTRAL	EMBASE (Ovid)	CINAHL (Ovid)	AMED (Ovid)
#1 HYPERBARIC OXYGENATION single term (MeSH) #2 oxygen* #3 HBOT #4 HBO #5 #1 or #2 or #3 or #4 #6 HEARING LOSS, SUDDEN single term (MeSH) #7 HEARING LOSS, SENSORINEURAL single term (MeSH) #8 sudden* #9 #7 and #8 #10 sshl #11 snhl #12 ishl #13 isshl #14 issnhl #15 ssnhl #16 (sudden near hearing) #17 (sudden near deaf*) #18 #6 or #9 or #10 or #11 or #12 or #13 or #14 or #15 or #16 or #17 #19 TINNITUS single term (MeSH) #20 tinnitus #21 #19 or #20 #22 #18 or #21 #23 #5 and #22	#1 exp HYPERBARIC OXYGEN/ #2 oxygen$.tw. #3 HBOT.tw. #4 HBO.tw. #5 or/1‐4 #6 exp SUDDEN DEAFNESS/ #7 exp PERCEPTION DEAFNESS/ #8 sudden$.tw. #9 7 and 8 #10 sshl.tw. #11 snhl.tw. #12 ishl.tw. #13 isshl.tw. #14 issnhl.tw. #15 ssnhl.tw. #16 (sudden adj3 hearing).tw. #17 (sudden adj3 deaf$).tw. #18 or/6,9‐17 #19 TINNITUS/ #20 tinnitus.tw. #21 (ear adj1 (buzz$ or ring$)).tw. #22 or/19‐21 #23 18 or 22 #24 5 and 23	#1 exp HYPERBARIC OXYGENATION/ #2 oxygen$.tw. #3 HBOT.tw. #4 HBO.tw. #5 or/1‐4 #6 exp HEARING LOSS, SENSORINEURAL/ #7 sudden$.tw. #8 6 and 7 #9 sshl.tw. #10 snhl.tw. #11 ishl.tw. #12 isshl.tw. #13 issnhl.tw. #14 ssnhl.tw. #15 (sudden adj3 hearing).tw. #16 (sudden adj3 deaf$).tw. #17 or/8‐16 #18 TINNITUS/ #19 tinnitus.tw. #20 (ear adj1 (buzz$ or ring$)).tw. #21 or/18‐20 #22 17 or 21 #23 5 and 22	#1 exp HYPERBARIC OXYGEN/ #2 oxygen$.tw. #3 HBOT.tw. #4 HBO.tw. #5 or/1‐4 #6 sshl.tw. #7 snhl.tw. #8 ishl.tw. #9 isshl.tw. #10 issnhl.tw. #11 ssnhl.tw. #12 (sudden adj3 hearing).tw. #13 (sudden adj3 deaf$).tw. #14 or/6‐13 #15 TINNITUS/ #16 tinnitus.tw. #17 15 or 16 #18 5 and (14 or 17)
Cochrane ENT Disorders Group Trials Register	PubMed	Web of Science/BIOSIS Previews (Web of Knowledge)	ICTRP
(hyperbaric OR hbo* OR oxygen* OR o2) AND (sudden OR sshl OR snhl OR ishl OR isshl OR issnhl OR ssnhl OR tinnit*)	#1 "Hyperbaric Oxygenation"[Mesh] #2 hyperbaric [tiab] OR HBOT [tiab] #3 #1 OR #2 #4 "Hearing Disorders"[Mesh] #5 sudden* [tiab] #6 #4 AND #5 #7 (sudden AND (hearing [tiab] OR deaf* [tiab] OR hypoacusis [tiab])) #8 sshl [tiab] OR snhl [tiab] OR ishl [tiab] OR isshl [tiab] OR issnhl [tiab] OR ssnhl [tiab] #9 "Tinnitus"[Mesh] #10 tinnit* [tiab] #11 (ear [ti] AND (buzz* [ti] or ring* [ti] OR roar* [ti] OR click* [ti] OR puls* [ti])) #12 #6 OR #7 OR #8 OR #9 OR #10 OR #11 #13 #3 AND #12	#1 TS=(hyperbaric OR hbot OR oxygen* OR o2) #2 TS=(tinnit*) #3 TS=(hearing or deaf* or sshl OR snhl OR ishl OR isshl OR issnhl OR ssnhl) #4 #3 OR #2 #5 #4 AND #1	sudden AND hyperbaric OR sudden AND hbo* OR hearing AND hyperbaric OR hearing AND hbo* OR hearing AND oxygen* OR tinnitus AND hyperbaric OR tinnitus AND hbo* OR tinnitus AND oxygen*