Tolerability of Nasal Delivery of Humidified and Warmed Air at Different Temperatures: A Randomised Double-Blind Pilot Study

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

INTRODUCTION

The common cold is the most common infectious disease affecting humans. It is usually a self-limiting disease; however, the common cold can cause significant morbidity and has a substantial economic impact on society. Human rhinoviruses (HRVs), which cause up to two-thirds of colds, have temperature-dependent replication and most HRV strains replicate optimally at 33°C. Delivery of heated, humidified air to the upper airways has the potential to reduce viral replication, but evidence of the effectiveness of this treatment of the common cold is inconclusive. We plan to test the hypothesis that delivery of humidified air heated to 41°C at high flow, nasal high flow rhinothermy (rNHF), for 2 hours daily for five days is more effective in reducing common cold symptom severity and duration than five days of 'sham' rhinothermy.

METHODS AND ANALYSIS

This is a randomised, single-blind, parallel-group trial comparing rNHF to 'sham' rhinothermy in the treatment of common cold. We plan to recruit 170 participants within 48 hours of the onset of symptoms of common cold and randomise them 1:1 to receive one of the two treatments for five days. The study duration is 14 days, which includes clinic visits on the first day of randomisation and four days post-randomisation, and a phone call on the 14th day. Participants will complete daily symptom diaries which include a symptom score, the Modified Jackson Score (MJS). The primary outcome is the MJS after four days.

ETHICS AND DISSEMINATION

New Zealand Ethics Registration: 17/STH/174. Results will be published in a peer-reviewed medical journal, presented at academic meetings, and reported to participants.

TRIAL REGISTRATION NUMBER

U1111-1194-4345 and ACTRN12617001340325; Pre-results.

Randomised controlled trial of rhinothermy for treatment of the common cold: a feasibility study

OBJECTIVE

To determine the feasibility of a randomised controlled trial (RCT) of rhinothermy for the common cold.

DESIGN

Open label, randomised, controlled feasibility study.

SETTING

Single-centre research institute in New Zealand recruiting participants from the community.

PARTICIPANTS

30 adult participants with symptoms of a common cold, presenting within 48 hours of the onset of symptoms.

INTERVENTIONS

Participants were randomly assigned 2:1 to receive either 35 L/min of 100% humidified air at 41°C via high flow nasal cannulae, 2 hours per day for up to 5 days (rhinothermy), or vitamin C 250 mg daily for 5 days (control).

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the proportion of screened candidates who were randomised. Secondary outcomes included: proportion of randomised participants who completed the study; modified Jackson scores from randomisation to 10 days after initiation of randomised regimen; time until feeling 'a lot better' compared with study entry; time until resolution of symptoms or symptom score at 10 days postrandomisation; proportion of organisms identified by PCR analysis of nasal swabs taken at baseline; the patterns of use of the rhinothermy device; estimated adherence of the control group; and rhinothermy device tolerability.

RESULTS

In all 30/79 (38%, 95% CI 27% to 50%) of potential participants screened for eligibility were randomised. Rhinothermy was well tolerated, and all randomised participants completed the study (100%, 95% CI 88% to 100%). The reduction from baseline in the modified Jackson score was greater with rhinothermy compared with control at days 2, 3, 4, 5 and 6, with the maximum difference at day 4 (-6.4, 95% CI -9.4 to -3.3). The substantial clinical benefit threshold for modified Jackson score was a 5-unit change.

CONCLUSIONS

This study shows that an RCT of rhinothermy compared with low-dose vitamin C in the treatment of the common cold is feasible.

TRIAL REGISTRATION NUMBER

ACTRN12616000470493; Results.