Sudden sensorineural hearing loss (SSNHL) is defined as acute hearing loss of >30 dB at three consecutive frequencies, with an abrupt onset (within 3 days). In most patients with SSNHL, an exact cause is rarely identified. Diverse etiological theories have been proposed, including vascular disease, viral infection, autoimmune disease, inner ear hydrops, and genetic factors. Based on these hypotheses, various treatments have been tried, including corticosteroids (systemic and/or intratympanic), antivirals, vasoactive drugs, and hyperbaric oxygen therapy (HBOT), but the evidence remains inconclusive. The 2019 American Academy of Otolaryngology-Head and Neck Surgery guideline had suggested that HBOT can be provided as either initial or salvage treatment when combined with steroid therapy. HBOT, a noninvasive treatment involving the inhalation of 100% oxygen at a pressure of >1 atmosphere absolute (ATA) is another treatment option as a method to improve oxygen supply after cochlear damage. Although the pressure, frequency, and total time of HBOT remain variable among different studies, a protocol of 2.0-2.5 ATA and 10-20 sessions in total are commonly used. The treatment strategies for SSNHL have been evolving, and recent attempts involved increasing the effectiveness through various combinations of systemic steroid, intratympanic steroid, and HBOT. In this review, we will review various studies about HBOT and discuss the efficacy of HBOT in SSNHL.

Background and Objectives: The purposes of this study were to compare the purchase rate and adherence regarding the use of two machines, continuous positive airway pressure (CPAP) and automatic positive airway pressure (APAP), and to determine associated factors affecting the purchase rate and adherence of PAP in the treatment of severe obstructive sleep apnea (OSA).Subjects and Method From March 2016 to December 2017, 45 patients diagnosed with severe OSA by polysomnography were enrolled in this study. Patients were prescribed CPAP or APAP by one doctor and allowed to decide whether to purchase the machine after a one-month lease period, which was identified as the purchase rate. Adherence was identified as using the machine 4 hight on 70% of nights following the PAP therapy of three months. Results: The adherence rate of CPAP (84%) was statistically and significantly higher than APAP (55%) (p=0.033). However, there was no significant difference in the adherence rate between CPAP (76%) and APAP (63%). The mean pressure and 95th percentile leak were 8.62 cm H2O and 12.97 L/min in the CPAP and 10.55 cm H2O and 20.36 L/min in the APAP, respectively. The mean pressure and 95th percentile leak were significantly lower in CPAP than in APAP (p=0.010 and p=0.014, respectively). Conclusion Although adherence was not significantly different, the purchase rate was significantly higher in the fixed CPAP than in APAP, which may have been influenced by high pressure and leak patients experienced when using the particular PAP machine.