None listed
Conditions
Brief summary
Background: Oxygen therapy has been a cornerstone of medical therapy since 1890. Current nasal oxygen cannula have been in use since 1949. Low flow oxygen via traditional nasal oxygen cannula (up to 15L/min) have been shown to modestly prolong time to desaturation when used while inducing general anaesthesia. High flow (± 60L/min) humidified nasal oxygen (HFNO) has been show to dramatically prolong time to desaturation. Apnoeic oxygenation has become well established clinical practice in recent years. Furthermore a volunteer study showed similar oxygen delivery when HFNO is compared to face mask ventilation. It is not known if similar oxygen delivery can be achieved using traditional cannula at high flows. Also the maximum flows achievable via nasal cannula from commonly available oxygen outlets has not been published. The first part of our study will be to establish this information using a gas flow analyser. Early work by our group has shown typical flows of ±55L/min. Our objective is to test the question of whether standard cannula supplying oxygen at high flows show comparable oxygen delivery to the well-researched proprietary HFNO systems. In addition to this we are interested to ascertain whether either therapy contributes significantly to gastric insufflation. Multiple previous case reports have been published of nasopharyngeal catheters resulting in gastric distension and rupture. No published data is yet available to demonstrate whether nasal cannulae, at high flow can also contribute to this potential complication. Our trial plan is to do a study of 30 healthy volunteers, comparing the oxygen delivery (via transcutaneous oxygen measurement) of HFNO via proprietary (humidified/ warmed) system (Optiflow, Fisher and Paykal, NZ) and comparing it to HFNO via traditional nasal cannula at high flow (±55L/min) and low flow (15L/min). Further parameters recorded and compared include; pharyngeal pressure generated, pharyngeal oxygen concentrations obtained, noise levels and participant comfort. A further key aspect of the study will be to examine whether gastric insufflation, a theoretical consequence of using a HFNO technique, does indeed result. For this, real time gastric ultrasound will be used.
Interventions
The purpose of this trial is to compare traditional nasal oxygen cannula at high flows with proprietary high flow nasal oxygen (HFNO) systems.
30 healthy volunteers (who are themselves anaesthetists) will receive proprietary HFNO or oxygen via nasal cannula at max flows. A 2 lumen line will be inserted nasally to the hypopharynx to record pressure and gas concentrations..
The following parameters will be recorded:
a. Transcutaneous pO2
b. Flow at which significant discomfort is reported
c. Phar
The purpose of this trial is to compare traditional nasal oxygen cannula at high flows with proprietary high flow nasal oxygen (HFNO) systems. 30 healthy volunteers (who are themselves anaesthetists) will receive proprietary HFNO or oxygen via nasal cannula at max flows. A 2 lumen line will be inserted nasally to the hypopharynx to record pressure and gas concentrations.. The following parameters will be recorded: a. Transcutaneous pO2 b. Flow at which significant discomfort is reported c. Pharyngeal pressure (via pressure inducer in pharynx- 2 lumen catheter) d. Pharyngeal gas concentrations / time to plateau (via gas sample in pharynx- 2 lumen catheter) e. Live gastric ultrasound to assess insufflation f. Sound intensity The intervention will be 2 x 5 minute sessions. Sessions will be separated by 10 minutes to facilitate oxygen washout. Oxygen will be delivered either at 60L/min via Optiflow or Max flow via standard cannula (previously measured at aprox 55L/min) In each case the concentration of oxygen is 100%. No pressure limiting device will be employed.
Sponsors
Fiona Stanley Hospital
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
Participant to be an anaesthetist. Healthy, non pregnant volunteers. No significant organ impairment of any kind. Aged 18-65. BMI 18-29 kg/m2.
Exclusion criteria
• Respiratory / airway disease. • Coagulopathy / anticoagulation or anti-platelet therapy. • History of severe epistaxis. • History of diabetes mellitus. • History of severe gastro-oesophageal reflux disease, hiatus hernia or previous gastro-oesophageal surgery. • Pregnancy. • Any displaced nasal injury or history of nasal congestion. • Participants unable to give informed consent. • No at-risk populations will be targeted for inclusion.
Outcome results
None listed