Dead Space in Mechanical Ventilation With Constant Expiratory Flow
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 13
- 试验地点
- 1
- 主要终点
- Change in Bohr dead space ventilation (VDBr/VT)
研究概览
简要总结
Conventional continuous mandatory mechanical ventilation relies on the passive recoil of the chest wall for expiration. This results in an exponentially decreasing expiratory flow.
Flow controlled ventilation (FCV), a new ventilation mode with constant, continuous, controlled expiratory flow, has recently become clinically available and is increasingly being adopted for complex mechanical ventilation during surgery.
In both clinical and pre-clinical settings, an improvement in ventilation (CO2 clearance) has been observed during FCV compared to conventional ventilation. Recently, Schranc et al. compared flow-controlled ventilation with pressure-regulated volume control in both double lung ventilation and one-lung ventilation in pigs. They report differences in dead space ventilation that may explain the improved CO2 clearance, although their study was not designed to compare dead space ventilation within the group of double lung ventilation.
Dead space ventilation, or "wasted ventilation", is the ventilation of hypoperfused lung zones, and is clinically relevant, as it is a strong predictor of mortality in patients with the acute respiratory distress syndrome (ARDS) and is correlated with higher airway driving pressures which are thought to be injurious to the lung (lung stress).
This trial aims to study the difference in dead space ventilation between conventional mechanical ventilation in volume-controlled mode and flow controlled-ventilation.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Double (Participant, Outcomes Assessor)
盲法说明
During analysis the groups (flow-controlled ventilation and volume-controlled ventilation) will be blinded.
Participants know that they will be exposed to both modes of ventilation, but are unaware of the randomized sequence (FCV-VCV or VCV-FCV).
It is impossible to mask the investigators delivering the intervention.
入排标准
- 年龄范围
- 18 Years 至 70 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Adults [18-70] yrs
- •General anaesthesia for elective surgery
- •Arterial line, central venous line and endotracheal tube as part of standard of care
- •Expected duration of controlled mechanical ventilation ≥ 60 minutes
- •Supine position (0±10°)
排除标准
- •One lung ventilation
- •Known pregnancy
- •Increased intra-abdominal pressure (pneumoperitoneum or obesity (BMI > 30kg/m2))
- •COPD GOLD IV or home oxygen dependence
- •Cardiac pacemaker, implantable cardioverter-defibrillator (ICD) or thoracic neurostimulator
- •Skin lesions (e.g. injury, inflammation) at the level where the Electrical Impedance Tomography (EIT) band is to be applied
- •Clinical signs of raised intracranial pressure
- •Potential interference with the surgery due to the setup of the study instruments.
- •Patient refusal to participate
研究组 & 干预措施
FCV-VCV
After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched FCV and subsequently 20 min of baseline-matched VCV.
干预措施: Flow-controlled ventilation (FCV) (Device)
FCV-VCV
After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched FCV and subsequently 20 min of baseline-matched VCV.
干预措施: Conventional volume-controlled ventilation (VCV) (Device)
VCV-FCV
After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched VCV and subsequently 20 min of baseline-matched FCV.
干预措施: Flow-controlled ventilation (FCV) (Device)
VCV-FCV
After titration of ventilation in baseline VCV (all arms), participants will first receive 20 min of baseline-matched VCV and subsequently 20 min of baseline-matched FCV.
干预措施: Conventional volume-controlled ventilation (VCV) (Device)
结局指标
主要结局
Change in Bohr dead space ventilation (VDBr/VT)
时间窗: During FCV and VCV measurements (20 minutes)
Quantified by the Bohr approach with volumetric capnography
次要结局
- Change in static airway compliance (Caw)(During FCV and VCV measurements (20 minutes))
- Change in end-tidal CO2 (ETCO2)(During FCV and VCV measurements (20 minutes))
- Change in inspiratory time (Ti)(During FCV and VCV measurements (20 minutes))
- Change in peak inspiratory pressure (PIP)(During FCV and VCV measurements (20 minutes))
- Change in global airway resistance (Raw)(During FCV and VCV measurements (20 minutes))
- Change in global airway time constant (TAUaw)(During FCV and VCV measurements (20 minutes))
- Change in peak expiratory flow (PEF)(During FCV and VCV measurements (20 minutes))
- Change in mean airway pressure (MPaw)(During FCV and VCV measurements (20 minutes))
- Change in minute ventilation (MV)(During FCV and VCV measurements (20 minutes))
- Change in positive end-expiratory pressure (PEEP)(During FCV and VCV measurements (20 minutes))
- Ventilatory efficiency (VE/VCO2)(During FCV and VCV measurements (20 minutes))
- Change in mean arterial pressure (MAP)(During FCV and VCV measurements (20 minutes))
- Change in plateau pressure (Pplat)(During FCV and VCV measurements (20 minutes))
- Change in dissipated energy(During FCV and VCV measurements (20 minutes))
- Change in physiological dead space volume (Vdfys)(During FCV and VCV measurements (20 minutes))
- Change in airway dead space volume (Vdaw)(During FCV and VCV measurements (20 minutes))
- Change in transpulmonary shunt fraction (Qs/Qt)(During FCV and VCV measurements (20 minutes))
- Change in Enghoff dead space ventilation (VDEng/VT)(During FCV and VCV measurements (20 minutes))
- Change in right-left distribution of ventilation on EIT (RL)(During FCV and VCV measurements (20 minutes))
- Change in 4-layered distribution of ventilation on EIT(During FCV and VCV measurements (20 minutes))
- Change in cardiac index (CI)(During FCV and VCV measurements (20 minutes))
- Change in alveolar dead space volume (Vdalv)(During FCV and VCV measurements (20 minutes))
- Change in airway driving pressure (∆Paw)(During FCV and VCV measurements (20 minutes))
- Change in global lung hyperdistention (hyperdistentionEIT)(During FCV and VCV measurements (20 minutes))
- Change in anterio-posterior distribution of ventilation on EIT (AP)(During FCV and VCV measurements (20 minutes))
- Change in centre of ventilation on EIT(During FCV and VCV measurements (20 minutes))
- Change in partial pressure of arterial CO2 (PaCO2)(During FCV and VCV measurements (20 minutes))
- Change in tidal volume (TV)(During FCV and VCV measurements (20 minutes))
- Change in expiratory time (Te)(During FCV and VCV measurements (20 minutes))
- Change in peak inspiratory flow (PIF)(During FCV and VCV measurements (20 minutes))
- Change in respiratory rate (RR)(During FCV and VCV measurements (20 minutes))
- Change in ratio of inspiratory time to total breath time (Ti / Tt)(During FCV and VCV measurements (20 minutes))
- Change in total energy(During FCV and VCV measurements (20 minutes))
- Change in P/F ratio(During FCV and VCV measurements (20 minutes))