Characteristic of volume-controlled ventilation with small tide volume in hyperbaric oxygen chamber
AUTHORS:
Cong Wang1, Lei Zhang1, Qiuhong Yu1, Yaling Liu1, Ziqi Ren1, Lianbi Xue2*
1Department of Hyperbaric Oxygen, Beijing Tiantan Hospital, Capital Medical University, A zone, No.199 Nansihuan West Road, Fengtai District, Beijing 100070, China
2Department of Hyperbaric Oxygen, Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), No. 89 Taoyuan Road, Nanshan District, Shenzhen 518052, China
*Corresponding Author, E-mail: xue40@vip.sina.com, Tel.: +86-0755-26553111-26681.
FULL TITLE: Characteristic of volume-controlled ventilation with small tide volume in hyperbaric oxygen chamber
SHORT TITLE: VCV IN HBO2 CHAMBER
ABSTRACT
Purpose: To evaluate the characteristics of tidal volume (VT) delivered by a Shangrila590 ventilator with preset tide volume (VTset) 50-300 mL in volume-controlled ventilation (VCV) during hyperbaric oxygen (HBO2) therapy.
Methods: Experiments were carried out in a multiplace HBO2 chamber at 1.0, 2.0, and 2.8 atmospheres absolute (atm abs) and divided into three groups accordingly. The ventilator was connected to the test lung in the chamber. The VTset of the ventilator was adjusted before the experiments. At 5 VTset levels (50, 100, 150, 200, 300 mL), the VT and inspiratory peak pressure (Ppeak) detected by the ventilator and the test lung were recorded for 30 cycles (n=30). The measurements of the test lung were considered to be the true value, and the ventilator and test lung data were compared to evaluate the accuracy of the ventilator. Test lung compliance (Ctl) was detected by the ventilator, and breathing circuit compliance (Cbc) was calculated by detecting the pressure and volume of the breathing circuit. Ventilation data were compared among three groups to clarify the change during HBO2.
Results: At every VTset, the VT detected by the test lung was different with the ventilator at 1.0~2.8 atm abs (p<0.05), and the VT changed differently among the three groups (p<0.05). Ctl and the Cbc decreased with ambient pressure increasing (p<0.05). The Ppeak of VCV increased (p<0.05) with ambient pressure increasing.
Conclusions: The Shangrila590 ventilator has limitations in small VTset (50- 300 mL) VCV during HBO2 therapy. Cbc and Ctl change because of high gas density. High Ppeak may occur in VCV with stable VT, also caused by high gas density.
Keywords
Tidal volume, airway resistance; compliance; hyperbaric oxygen; intermittent positive-pressure ventilation; ventilators