title: FLOW-i ventilator performance in the presence of a circle system leak.
abstract: Recently, the FLOW-i anaesthesia ventilator was developed based on the SERVO-i intensive care ventilator. The aim of this study was to test the FLOW-i's tidal volume delivery in the presence of a leak in the breathing circuit. We ventilated a test lung model in volume-, pressure-, and pressure-regulated volume-controlled modes (VC, PC, and PRVC, respectively) with a FLOW-i. First, the circuit remained airtight and the ventilator was tested with fresh gas flows of 6, 1, and 0.3 L/min in VC, PC, and PRVC modes and facing 4 combinations of different resistive and elastic loads. Second, a fixed leak in the breathing circuit was introduced and the measurements repeated. In the airtight system, FLOW-i maintained tidal volume (VT) and circuit pressure at approximately the set values, independently of respiratory mode, load, or fresh gas flow. In the leaking circuit, set VT = 500 mL, FLOW-i delivered higher VTs in PC (about 460 mL) than in VC and PRVC, where VTs were substantially less than 500 mL. Interestingly, VT did not differ appreciably from 6 to 0.3 L/min of fresh air flow among the 3 ventilatory modes. In the absence of leakage, peak inspiratory pressures were similar, while they were 35-45 % smaller in PRVC and VC than in PC mode in the presence of leaks. In conclusion, FLOW-i maintained VT (down to fresh gas flows of 0.3 L/min) to 90 % of its preset value in PC mode, which was 4-5 times greater than in VC or PRVC modes.
authors.affiliation: Department of Perioperative Medicine, Intensive Care and Emergency, University of Trieste, Trieste, Italy. u.lucangelo@fmc.units.it.|Department of Engineering and Architecture, University of Trieste, Trieste, Italy. u.lucangelo@fmc.units.it.
authors.forename: Umberto
authors.initials: U
authors.lastname: Lucangelo
authors.affiliation: Department of Engineering and Architecture, University of Trieste, Trieste, Italy.
authors.forename: Miloš
authors.initials: M
authors.lastname: Ajčević
authors.affiliation: Department of Engineering and Architecture, University of Trieste, Trieste, Italy.
authors.forename: Agostino
authors.initials: A
authors.lastname: Accardo
authors.affiliation: Department of Mathematics and Computer Science, University of Trieste, Trieste, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Borelli
authors.affiliation: Department of Perioperative Medicine, Intensive Care and Emergency, University of Trieste, Trieste, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Peratoner
authors.affiliation: Department of Perioperative Medicine, Intensive Care and Emergency, University of Trieste, Trieste, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Comuzzi
authors.affiliation: Carlos Chagas Filho Institute of Biophysics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Walter A
authors.initials: WA
authors.lastname: Zin
mesh_terms: D000764:Anesthesia, Closed-Circuit / Q000295:instrumentation*; D002245:Carbon Dioxide; D003422:Critical Care; D004867:Equipment Design; D005740:Gases; D006801:Humans; D016014:Linear Models; D010100:Oxygen; D011175:Positive-Pressure Respiration; D011312:Pressure; D012119:Respiration; D012121:Respiration, Artificial / Q000295:instrumentation*; D015656:Respiratory Mechanics; D013990:Tidal Volume; D012122:Ventilators, Mechanical
chemical_list: D005740:Gases; D002245:Carbon Dioxide; D010100:Oxygen
keywords: Air leaks; Low flow anaesthesia; Mechanical loads; Ventilatory modality; Volume reflector