Performance of heated humidifiers with a heated wire according to ventilatory settings

Citation
T. Nishida et al., Performance of heated humidifiers with a heated wire according to ventilatory settings, J AEROSOL M, 14(1), 2001, pp. 43-51
Citations number
12
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Envirnomentale Medicine & Public Health
Journal title
JOURNAL OF AEROSOL MEDICINE-DEPOSITION CLEARANCE AND EFFECTS IN THE LUNG
ISSN journal
0894-2684 → ACNP
Volume
14
Issue
1
Year of publication
2001
Pages
43 - 51
Database
ISI
SICI code
0894-2684(200121)14:1<43:POHHWA>2.0.ZU;2-8
Abstract
Delivering warm, humidified gas to patients is important during mechanical ventilation. Heated humidifiers are effective and popular. The humidifying efficiency is influenced not only by performance and settings of the device s but the settings of ventilator. We compared the efficiency of humidifying devices with a heated wire and servo-controlled function under a variety o f ventilator settings. A bench study was done with a TTL model lung. The st udy took place in the laboratory of the University Hospital, Osaka, Japan. Four devices (MR290 with MR730, MR310 with MR730; both Fisher & Paykel, Con chaTherm IV; Hudson RCI, and HummaxII; METRAN) were tested. Hummax II has b een developed recently, and it consists of a heated wire and polyethylene m icroporous hollow fiber. Both wire and fiber were put inside of an inspirat ory circuit, and water vapor is delivered throughout the circuit. The Servo 300 was connected to the TTL with a standard ventilator circuit. The venti lator settings were as follows; minute ventilation ((V) over dot(E)) 5, 10, and 15 L/min, a respiratory rate of 10 breaths/min, I:E ratio 1:1, 1:2, an d 1:4, and no applied PEEP. Humidifying devices were set to maintain the te mperature of airway opening at 32 degreesC and 37 degreesC. The greater (V) over dot(E) the lower the humidity with all devices except Hummax II. Humm ax II delivered 100% relative humidity at all ventilator and humidifier set tings. When airway temperature control of the devices was set at 32 degrees C, the ConchaTherm IV did not deliver 30 mg/L of vapor, which is the value recommended by American National Standards at all (V) over dot(E) settings. At 10 and 15 L/min of (V) over dot(E) settings MR310 with MR730 did not de liver recommended vapor, either. In conclusion, airway temperature setting of the humidifying devices influenced the humidity of inspiratory gas great ly. Ventilatory settings also influenced the humidity of inspiratory gas. T he Hummax II delivered sufficient water vapor under a variety of minute ven tilation.