Figures
- Figure 1
Double limb respiratory circuit a) without and b) with a flow sensor (F) sited distal to the Y-piece. The black and yellow arrows indicate the direction of inspiratory and expiratory flow, respectively. See the main text for further explanation.
- Figure 2
Single limb “non-vented” respiratory circuit with an exhalation valve (V) sited at a) the distal end of the inspiratory circuit or b) at the end of a short expiratory limb. In both cases, the exhalation valve is driven by the ventilator pressure (green line). The black and yellow arrows indicate the direction of inspiratory and expiratory flow, respectively. See the main text for further explanation.
- Figure 3
Examples of single limb “vented” circuits. Exhalation occurs through single or multiple orifices sited either in a) the mask shell or in the swivel connector (O), b) a whisper swivel (W) or a hole orifice at the distal end of the circuit (H), or c) a “Plateau Valve” (P) positioned between the circuit and the mask. The black and yellow arrows indicate the direction of inspiratory and expiratory flow, respectively. See the main text for further explanation.
Tables
- Table 1 Elements of a positive pressure ventilator
1. Respiratory circuit 2. Pneumatic system 3. Inspiratory and expiratory valves 4. Trigger, limit, cycling and control variables 5. Modes of mechanical ventilation 6. User interface 7. Safety and alarm systems 8. Monitoring system 9. Accessories - Table 2 Criteria for a flow-cycled breath to cycle to baseline pressure
Flow reaches a predetermined percentage of inspiratory peak flow (usually 25%) Flow reaches a pre-set percentage of inspiratory peak flow (e.g. from 1% to 80%) According to particular algorithms linked to flow value or waveform (e.g. Philips Respironics AutoTrak system) - Table 3 Home care ventilator alarms
1. Electrical failure 2. Patient disconnection from the ventilator 3. High non-intentional leaks 4. Apnoea in assisted modes 5. High and low and minimum patient rate 6. High pressure and low pressure limit (especially in volume-controlled mode) 7. Changes in VT (in pressure-targeted mode) 8. Changes in minute ventilation (in volume- or pressure-controlled modes) 9. Changes in FIO2 when used - Table 4 Type of ventilator according to interface and the patient's underlying disease
Ventilator definition Interface Underlying disease Type of RC Ventilatory modes Alarms Monitoring Battery Accessories Life support TT or NIV >16 h·day−1 e.g. ALS, High-level quadriplegia, advanced DMD, SMA I Double or single RC with a non-rebreathing expiratory valve ACV , VTG modes and any other Full range# Full range > 8 h¶ A 12/24 V car plug for battery recharge Brackets to mount the unit on the wheel chair Life sustaining NIV <16 h·day−1 e.g. COPD, OHS, early DMD Any including “vented” circuit APCV, S/ST, PSV VTG modes Basic range+ Basic range Irrelevant Irrelevant RC: respiratory circuit; TT: tracheostomy tube; ALS: amyotrophic lateral sclerosis; DMD: Duchenne muscular dystrophy; SMA I: spinal muscle atrophy type I; COPD: chronic obstructive pulmonary disease; OHS: obesity hypoventilation syndrome; S/ST: spontaneous/spontaneous-timed. #: as described in points 1–9 in table 3; ¶: including an external battery pack; +: as described in points 1–4 of table 3.
