Protocol for a randomised, single-blind, two-arm, parallel-group controlled trial of the efficacy of rhinothermy delivered by nasal high flow therapy in the treatment of the common cold

Bird, Grace; Braithwaite, Irene; Harper, James; McKinstry, Steven; Koorevaar, Iris; Fingleton, James; Semprini, Alex; Dilcher, Meik; Jennings, Lance; Weatherall, Mark; Beasley, Richard

Studies conducted in vivo have delivered heated and humidified air to participants at a range of temperatures, from 40 to 44°C, [8, [12] [13] [14] [15] and using a variety of devices, including an anaesthetic mask [12] and steam-venting nozzles held a distance away from the nares. [8, [13] [14] [15] These delivery systems may be inefficient and inconsistently deliver humidified air to the upper airways at the desired temperatures. A recent Cochrane systematic review of six rhinothermy studies in which participants with the common cold were treated with heated, humidified air did not show any harms or benefits, but advised cautious interpretation of the evidence, concluding that its quality was low grade. [1] The review recommended that further double-blind randomised controlled trials are needed, which provide definitive diagnosis derived from viral cultures and use uniform symptom scores. [1] It is evident that future trials should use standardised treatment modalities which effectively and consistently raise the temperature of the upper airways for the duration of treatment. A recent feasibility study recruited 30 participants with symptoms of the common cold into a randomised controlled trial (RCT) of five days of rNHF therapy or Vitamin C with the main patient reported outcome measure, the Modified Jackson Score. [17] The rNHF therapy delivered 100% humidified air at 35L/min and 41°C for two hours daily. Compared to Vitamin C, rNHF treatment caused a clinically significant five unit reduction in the Modified Jackson Score.