Mode of Ventilation

• Pressure- controlled ventilation
Pressure vs. Volume Ventilation
Pressure vs. Volume Ventilation: Advantages
• • • • • • PC & PSV Variable flow rate Reduced WOB Max Palveolar = Max Pairway (or less) Palveolar controlled Variable P-time & pattern (PS) Better with leaks
Factors that affect volume delivery during pressure ventilation
1. Pressure Setting • ↑ pressure setting → ↑ volume ( vice versa). 2. Pressure Gradient (ΔP) 3. Patient Lung Characteristics • compliance • Raw 4. Inspiratory Time • ↑Ti → ↑ volume delivery . • flow returns to zero before inspiration ends, ↑ Ti doesn’t ↑ volume. 5. Patient Effort • Active inspiration by the patient can increase volume delivery.
Partial Ventilatory Support
• Mechanical ventilation < 6 breaths/mm and the patient participates in WOB to help maintain effective alveolar ventilation. (patient actively participates in ventilation to maintain adequate levels of PaCO2.) • PVS modes might include SIMV, PSV, VS, PAV, MMV. • PVS strategies : • when attempts to discontinue ventilator support. • avoided patients ventilatory muscle fatigue
• • • • •
Volume Control Consistent TV changing impedance Auto-PEEP Minimum min. vent. (f x TV) set Variety of flow waves
Pressure vs. Volume Ventilation: Disadvantages
Mode of Ventilation
江苏海企国际有限公司呼吸治疗师 瑞思迈无创呼吸机产品专员 胡积亮
LEARNING OBJECTIVES
• Explain the positive or negative pressure ventilation, invasive or noninvasive ventilation, volume or pressure ventilation, and full or partial ventilatory support. • Compare the advantages and disadvantages of volume and pressure ventilation. • Explain the differences in function among continuous mandatory ventilation(CMV ; also called assist/control ventilation), synchronized intermittent mandatory ventilation (SIMV), and spontaneous ventilation
• Volume- limited ventilation • Volume- controlled ventilation
Common Methods of Delivering Inspiration
2.PRESSURE VENTILATION The operator sets a pressur Pressure ventilation is also called • Pressure- targeted ventilation • Pressure- limited ventilation
Dual Control Ventilation
• Volume control to Pressure Control:
• Attempts to deliver a constant tidal volume while limiting peak pressure
• Pressure control to Volume Control:
Volume Control • Variable pressures • Airway P. • Alveolar P. • Fixed flow pattern • Variable effort = variable work/breath • Compressible vol. • Leaks = vol. loss
PC & PSV
• Variable tidal
volume • Too large or too
small
• No alarm/limit for excessive TV (except some new gen. vents) • Some variablity in max pressures (PC, expir. effort) ?
壓力上升速度快慢 之影響 B1 過 快 B2 過慢 PPlate
insp.termination 延 緩，故 P’t 做主動吐 氣 ( D2 )即屬壓力 cycle
D1 吸氣結束
trigger
10
Factors That Affect Pressures during Volume Ventilation
Noninvasive Positive Pressure Ventilation
• The application of positive pressure via the upper respiratory tract for the purpose of augmenting alveolar ventilation • NPPV typically is administered through a nasal or an oral mask – unlike invasive positive pressure ventilation (through an endotracheal or tracheostomy tube ARFC Consensus Conference: non-invasive positive pressure ventilation: consensus statement, Respir Care 42:362, 1997
Common Methods of Delivering Inspiration
1. VOLUME VENTILATION The operator sets a volume for delivery Volume ventilation is also called • Volume- targeted ventilation
• Attempts to limit peak pressure but assures tidal volume delivery
• Disadvantage:
• Requires high degree of understanding • Difficult to adjust and maintain
Goals of Noninvasive Positive Pressure Ventilation
Factors OF Determine
1. Targeted control variable ： volume , pressure , dual ( volume + pressure) 2. Type of breath ： mandatory & spontaneous assisted & unassisted、supported & unsupported 3. Timing of breath delivery ： CMV :Continuous mandatory ventilation SIMV: Synchronized intermittent mandatory ventilation 4. Spontaneous ventilation: ATC,T-piece, CPAP, PSV,PAV,PPS .
1. Patient lung characteristics • compliance • airway resistance 2. Inspiratory flow pattern • constant flow and lower with a descending ramp Peak pressure is higher • ↑ insp. gas flow a higher peak pressure. 3. Volume setting 4. Positive end-expiratory pressure • ↑PEEP PIP ↑ 5. Auto-PEEP
• Define each of the following terms: PA, PRVC, VS, MMV, airway pressure release ventilationAPRV, BIPAP, andPAV. • Give examples of the type of patient who would benefit most from each mode of ventilation.
Full Ventilatory Support
• Ventilator provides all energy to maintain effective alveolar ventilation. • FVS is provided ventilator rates > 8 breaths/mm and VT is adequate for patient. ( Vt 6~12 ml/kg of IBW). • ensures patient is not required to assume any of WOB. • can using ventilator mode to deliver volume or pressure breath. • FVS might include fully controlled and assistcontrol positive pressure ventilation.
LEARNING OBJECTIVES
• Use the terms trigger, cycle, and limit to define the following modes
• graph pressure/time to show the pressure delivered with each mode: V-CMV,V-SIMV PCMV, P-SIMV, and PSV