Mechanical Ventilation (CMV, HFOV, HFJV) Flashcards
What are the 4 types of ventilator-induced lung injury?
Barotrauma
Volutrauma
Biotrauma
Atelectotrauma
Barotrauma
Using pressures that are too high
Volutrauma
Expanding the lungs too much (tidal volume)
- The most common cause of lung injury
Biotrauma
Lung injury associated with infection
Atelectotrauma
Allowing the lung to develop atelectasis which prevents the alveoli from staying open
When was the first conventional neonatal ventilator designed and what made it unique?
1970s
- Allowed continuous flow through respiratory cycle
- Delivered continuous PEEP, was time-cycled and pressure limited, and could provide intermittent mandatory ventilation (IMV)
When was CPAP proposed?
1971 (for the treatment of RDS)
What is the primary goal of mechanical ventilation?
Safe, effective gas exchange
What are 4 important therapies to reduce lung injury and BPD in neonates receiving mechanical ventilation?
Surfactant, caffeine, avoiding a pneumo, reducing nosocomial infections
What are the characteristics of “intermittent mandatory ventilation” (IMV)?
A mode of conventional ventilation in which all mechanical breaths are delivered at regular intervals, regardless of respiratory effort
- May lead to inefficient ventilation, pneumothorax, IVH
- Spontaneous breaths supported by PEEP only, which may increase WOB
What are the characteristics of “synchronized intermittent mandatory ventilation” (SIMV)?
This mode of conventional ventilation is patient-triggered
- Each inspiratory effort that exceeds a trigger threshold during a certain time frame results in a mandatory mechanical breath
- If patient fails to breathe, a breath is provided
- Spontaneous breaths are unsupported
What are the characteristics of “assist/control” (AC) ventilation?
In this mode of conventional ventilation, each spontaneous breath that exceeds a trigger threshold leads to the delivery of a mechanical breath (assist) synchronous to patient’s inspiratory effort
- If the patient fails to breathe or doesn’t trigger the sensitivity threshold, a breath (control) is provided at the preset interval
What are the characteristics of “pressure support ventilation” (PSV)?
A mode of conventional ventilation that applies a burst of inspiratory pressure to spontaneous breaths
- Used in conjunction with SIMV if patient doesn’t have reliable respiratory drive
- Patient-triggered (initiated and terminated)
- Can be adjusted to provide full or partial support
What is the “trigger” feature of mechanical ventilation?
The mechanism used to initiate a breath, which may be time, airway pressure, or flow
What is the “limit” feature of mechanical ventilation?
The targeted variable (pressure or volume)
What is the “time-cycling” feature of mechanical ventilation?
A mechanism in which inspiration ends after a preset inspiratory time (i-time)
- Every breath is identical
What is the “flow-cycling” feature of mechanical ventilation?
A mechanism in which inspiration ends when decelerating inspiratory flow is a small percentage of PIP (doesn’t have to reach zero-flow state)
- Enables patient to control i-time and rate while allowing for inspiratory and expiratory synchrony
- Safeguards against gas trapping
Describe pressure and volume in pressure-targeted ventilation
Pressure is limited, volume is variable (depends on lung mechanics)
- Mechanical breaths are initiated and terminated by time
- Inspiratory flow is constant
- Can be delivered using SIMV, IMV, or AC
Conventional ventilation can be pressure-targeted or volume-targeted. What are the two types of pressure-targeted ventilation?
Pressure Control (PC): variable inspiratory flow (proportional to patient effort) - Breath is "front-end loaded" as peak pressures and tidal volumes are delivered early in inspiration
Pressure Support (PS): pressure is limited, inspiratory flow is variable - Applied only to spontaneous breaths and may be used during weaning phase
Describe pressure and volume in volume-targeted ventilation
Volume is limited, pressure is variable
- As lung compliance improves, pressure is weaned to provide target volume
- Inspiratory flow is held constant until inspiration ends
What are 3 short-term benefits of SIMV over IMV?
- Oxygen stability
- Patient comfort
- Shorter duration of support
What is unique about high frequency ventilation?
Provides smaller tidal volumes at rapid rates
- A high PEEP recruits alveoli and maintains lung volume at a constant level with small changes in tidal volume to help accomplish ventilation
What are the primary goals of ventilation (CMV and HFV)?
- Maintain adequate lung volume
- Avoid atelectasis
- Preserve surfactant function
- Maximize ventilation-perfusion match and avoid cardiac output impairment
Which type of HFV delivers small tidal volumes at rates between 240-660 breaths per minute?
HFJV
