2006 OPEN FORUM Abstracts
Comparison of High Flow Nasal Cannula (HFNC) Devices
*Brian K. Walsh, RRT-NPS, RPFT, ^Douglas Petsinger, RRT-NPS, tEric Hurd, RRT
*
University
of
Virginia
Children
's
Hospital, ^Children's Healthcare of Atlanta,t
Georgetown
University
Background: The
concept of high flow and high humidity via a nasal cannula (HFNC) was first
introduced by Vapotherm to the respiratory care market in the spring of 2002
after receiving FDA approval. This introduction lead to the development of HFNC
strategies that has proven to be an acceptable intensive care modality for
rescue from endo-tracheal intubation, bridging from endo-tracheal mechanical ventilation, and long term
supportive care of the growing neonate. Initially, the Vapotherm
Nasal Cannula System (Vapotherm,
Stevensville
,
MD
,
USA
) was the first widely used high flow NC system until several reports of
restonia infection were reported by various hospitals. In
December 22nd,
2005
Vapotherm voluntary
recalled their device. The HFNC strategy has continued as a viable practice
with other humidification devices. However, concerns with these new devices
are: comparison humidification output, and alarms.
Method: We compared the humidity and safety features of three
devices. Humidification was sampled using a high performance digital
thermo-hygrometer (Omega Engineering,
Stamford
,
CT
) at the distal end of the delivery circuit. The baseline
room temp was 22o C with a RH of 12%. Each of the devices was set-up
according to manufacture recommendations with the exception of the Fisher Paykel
(F&P East Tamaki,
New Zealand
). This device was set-up according to common practice
described on the AARC Neonatal Pediatric list serve from March 16th-27th.
The F&P temperature setting was set on invasive and the pop-off was removed
to achieve higher flows (off label use) in order to do a direct comparison.
Oxygen flow from 1-8 l/min was sent through the Infant Continuous Low Flow
Circuit by F&P and the Low Flow cartridge and circuit by Vapotherm. Oxygen
flow of 15-35 l/min was sent through the Aquanox HF
Humidification System (Smiths Medical, Kent UK) and High Flow cartridge by
Vapotherm. In all cases the temperature and humidity output was monitored for
30 minutes and recorded in 5 minute increments. Safety features and alarms of
each of the devices were tested. Common clinical events were replicated in the
lab setting. The delivery tube was occluded, the oxygen source was disconnected
and then reconnected after 5 minutes, and humidifier water supply and reservoir
was depleted on each of the devices.
Results: Humidity-There was a statistical
difference in the RH% between the F&P and Vapotherm
devices (t-test p=0.015). There was no statistical difference in RH% of the
Vapotherm and Aquanox systems (rank sum p=0.667). Safety-Two out of the three devices have
heater alarms that function appropriately. When the delivery tubing was
deliberately occluded, the F&P device has a silent pop-off, the Vapotherm
has an audible electronic and manual pop-off valve, the AquinOx
has a single pop-off sound and the circuit has to be manually put back
together. When the source gas was deliberately disconnected, the Vapotherm device would alarm immediately, the F&P
device had a delayed alarm up to 8-15 minutes later depending on flow rate.
None of the devices over shot the baseline temperature when disconnected and
reconnected after 5 minutes. Only the Vapotherm and F&P
devices alarmed in low water states. See Figure 1.
| Figure 1 | Flow Settings liters/minute | Setting | Average RH% | Heater Alarms | Disconnect Alarm | Auditable Pop-off Alarm | |
| Device | |||||||
| Vapotherm | 1-8 | 37 | 98.75% | ü | ü | ü | |
| F&P | 1-8 | Invasive | 95.75% | ü | |||
| AquinOx | 15-35 | Max | 98.5% | ü | |||
| Vapotherm | 15-35 | 37 | 98% | ü | ü | ü | |
Conclusion: Vapotherm
in the 1-8 liter/minute delivered the highest RH%. There was no difference in
RH% between the AquinOx and Vapotherm
systems with flows >15 L/min. Vapotherm has the
most safety features of all three devices which could possibly prevent adverse
events.