High Flow Nasal Cannula Compared to Continuous Positive Airway Pressure in the Treatment of Obstructive Sleep Apnea
Phase: NA
Conditions: Obstructive Sleep Apnea
Sponsor: Chung-Chieh, Yu

Title: High flow nasal cannula compared to continuous 
positive airway pressure in the treatment of obstructive sleep 
apnea 
 
Investigator: Chung-Chieh, Yu  
 
Official Title: Director of Sleep Center 
 
NCT number: NCT03843372 
 
Document date:  June 08, 2020 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Materials and Methods 
This work was approved by the institutional review board of Chang Gung 
Memorial Hospital (201601844B0C101), and all subjects signed 
informed consent forms in accordance with the amended Declaration of 
Helsinki. Subjects who were diagnosed with OSAHS via standard 
polysomnography (PSG) were recruited in the sleep center of Chang 
Gung Memorial Hospital. The definition of OSAHS was an AHI greater 
than 5 times per hour (times/hr). Patients with central sleep apnea, 
hypoventilation syndrome, chronic obstructive airway disease, an 
unstable hemodynamic state, who were younger than 18 years old, with 
an Eastern Cooperative Oncology Group Performance Status higher than 
grade 2, who experienced intolerance to HFNC or CPAP, and pregnant 
women were excluded. In addition, patients who recently underwent 
surgery or used an oral appliance were also excluded. 
 
Study Protocols 
This was a prospective crossover study. All of the participants were 
randomized into two groups for minimized first night effects. All of them 
would receive one-night HFNC therapy and another night for CPAP 
titration under PSG monitoring. The duration between these two 
treatments was approximately one week apart. The first group underwent 
CPAP titration on the first night and HFNC titration on the second night. 
Conversely, the second group was subjected to HFNC on the first night 
and CPAP titration on the second night. All of the participants were asked 
and recorded their side effects following completion of an HFNC or 
CPAP. 
 
Polysomnography and scoring methods 
Standard overnight PSG included recording electroencephalography, 
bilateral electroculograms, submental electromyogram, 
electrocardiography, nasal pressure, oronasal thermistor, oximetry, chest, 
and abdominal movement (inductance plethysmography), body position, 
sound intensity, and bilateral tibia electromyogram. All signal results for 
each night were collected and digitized on a computerized PSG system 
(Embla N7000, USA; Compumedics, Australia). Sleep stages and 
respiratory events were scored according to the American Academy of 
Sleep Medicine (AASM, Version 2.4; 2017) scoring manual. 
 

 
CPAP titration 
All patients underwent a nasal CPAP titration study in the sleep 
laboratory for an entire night. During the CPAP titration study, manual 
CPAP titration was conducted to determine the optimal CPAP level 
required. A CPAP interface was individually fitted from a wide range of 
interfaces to maximize comfort and minimize leaks. The preparation of 
the patients was accomplished by a trained PSG technician who 
supervised the study. All of the participants used a CPAP mask and 
machine (System one, Philip Respironic, US) throughout the study. 
Preparation of the patients was accomplished the technician who 
supervised the study and corrected the mask position and fitting initially. 
All of the patients were started at a low pressure (4 cm H2O) initially, and 
then the pressure was manually increased after the patients went to sleep. 
The pressure sensor was used to evaluate apneas, hypopneas, and flow 
limitations. The optimal CPAP pressure was determined to be the pressure 
that could eliminate apnea, hypopnea, desaturation, and snoring in a 
supine position or when possible in REM sleep [18]. 
 
High flow titration 
All participants underwent high flow titration in the sleep laboratory for 
an entire night. An air compressor (AIRVOTM2, Fisher &Paykel 
Healthcare, Auckland, New Zealand) delivered the airflow via nasal 
cannula (Optiflow). A heating tube (900PT500) and humidifier kept the 
temperature at 34–37oC and absolute humidity of 44mg/L. The initial 
flow rate was set as 20L/min. After the patients fell asleep, the flow rate 
was increased by 10L/min up to a maximum of 60L/min to try to 
eliminate apneas, hypopneas, and desaturation in the supine position or 
REM sleep. This principle was similar to the CPAP titration; however, 
RIP signals were used to distinguish the respiratory events. If the 
participants become awake or complain that the flow rate was too high or 
uncomfortable, the flow rate would be decreased 10 L/min until they 
could return to sleep. When the subject fell asleep again, the flow rate 
would be increased again to try and discover the optimal flow rate that 
could maintain sleep and achieve a favorable AHI reduction. The flow 
rate that could maintain sleep, plus the best AHI was defined as the 
optimal flow rate. Once the optimal flow rate was determined, the 
subjects were allowed to sleep at that flow rate for the rest of the night. 

 
Statistical analysis 
  The most of respiratory event and sleep quality parameters were not 
normal distribution. Therefore, the carry over effect of CPAP and HFNC 
were evaluated by Wilcoxon rank sum test. The AHI, desaturation index, 
sleep efficiency, and total sleep time between CPAP titration, and HFNC 
were also compared with the Wilcoxon rank sum test. The side effects of 
HFNC and CPAP were compared with the chi-square test and Fisher’s 
exact probability test. A p-value < 0.05 was considered statistically 
significant. Statistical evaluations were performed using the SPSS 16.0 
Software (SPSS Inc., Chicago, Ill). Data were presented as median ± 
interquartile range (IQR). P-values < 0.05 were considered to be 
statistically significant.