Mechanical Ventilators Flashcards
Purpose of Ventilator
- decrease WOB
- provide ventilation (not respiration)
- maintain positive pressure
Mechanical Ventilator
- process by which ventilation is maintained by an artificial or extrinsic means
- machine used to force gas into lungs
Indications of ventilator use
- inability to spontaneously ventilate
- disorder of gas exchange (unable to get O2 in or CO2 out)
Negative Pressure Ventilator
- Iron Lung
- change in pressure in caase around chest to increase/decrease intrathoracic pressure to ventilate patient
Pressure Support Ventilation
- pt must have adequate spontaneous effort
- provide preset amount of pressure during spontaneous effort to support pt efforts
Acute/impending respiratory failure
-pH 50mmHg
Types of Ventilators
- negative pressure (iron lung)
- positive pressure
Positive Pressure Ventilator
- blows air into lungs
- affected by compliance and resistance
Volume-Cycled ventilation
ends inspiration after a preset tidal volume has been delivered
3 types of positive pressure ventilation
- volume-cycled
- time-cycled
- flow-cycled
Time-cycled ventilation
-ends inspiration after preset time has elapsed
Flow-Cycled
-ends inspiration when a preset flow rate is obtained
CPAP
- applies continuous positive pressure during inspiration and expiration to a spontaneously breathing person
- pressure prevents alveolar collapse, increased fuctional/residual capacity and oxygenation
Indications for CPAP
- atelectasis
- sleep apnea
Advantages vs Disadvantages of CPAP
ADV-maintain respiratory strenth, used to wean from partial vent support
DIS-possible compromise to CO
Advantages vs Disadvantages of SIMV
ADV: to wan pts from vent, less likely to hypervent, CO less compromised
DIS: utilize demand valve that opens and allows airflow in response to certain neg pressures
Assist Control Ventilation
- preset rate and tidal volume programmed, which are delivered in absence of spontaneous effort
- in response to effort, will assist pt’s efforts by delivering the tidal volume
Indications of Assist Control Ventilation
pt with respiratory Mm fatigue, pulm edema or pneumonia
Advantages vs Disadvantages of Assist Control Vent
ADV: pt may participate in vent
DIS: possibly hyperventilate
Advantages vs Disadvantages of Pressure Support Ventilation
ADV: incr tidal volume to decr WOB & aids in weaning
DIS: difficult to ensure alveolar vent; no air given in absence of voluntary effort; increase tidal volume & decr RR
BiPAP
- similar to CPAP but gives different levels of pressure during inhale and exhale
- help deliver more air to lungs
- used for same problems as CPAP
Ventilator Parameters
- tidal volume
- RR
- FiO2
- PEEP
- PIP
PIP
- peak inspiratory pressure
- how much force is needed to get air into lungs
- if have restrictive or intubated=need greater amount
- trauma risk: barotrauma
High Pressure Alarm
- alarms when PIP exceeds preset limit
- indicates obstruction in tracheal tube or pt coughing/being agitated
- may indicate worsening condition
Low PEEP/CPAP alarm
-when preset PEEP or CPAP not maintained
Low exhaled volume alarm
- when exhale volume is < tidal volume
- indicates pt disconnected from tracheal tube or leak in cuff around tube
6 Alarms
- high/low pressure alarms
- low PEEP/CPAP alarm
- High/low exhaled volume alarm
- apnea alarm
Low pressure alarm
- when tidal volume uses pressure below average PIP
- indicates leak in system
High Exhaled Volume Alarm
- pt getting more than preset minute ventilation
- if pt incr RR or agitated
Apnea Alarm
- when no air movement detected for period of time
- indicates system failure or nonexistent O2 supply
- initiate emergency procedures ASAP
factors affecting weaning
- ABGs
- PFTs
- Presence of Contraindications
Weaning Complications
- Atelectasis
- Aspiration
- Hypoxemia
Signs of respiratory distress during mechanical vent
- increased SCM contraction
- recession of suprasternal and supraclavicular spaces and intercostal spaces
- paradoxical motion of abdomen
- diaphoresis
- nasal flaring
- tachycardia
- tachypnea
- cyanosis
Contraindications to weaning
- Required PEEP >5cm H20
- if FIO2 >0.4
- Unable to generate negative inspiratory pressure >/= 20 mmHg
5 modes of ventilation
- assist-control ventilation
- synchronized intermittent mandatory vent (SIMV)
- Pressure support vent
- CPAP
- BiPAP
SIMV
- programmed to deliver preset tidal volume and frequency
- if pt fails to initiate, will deliver tidal volume and rate
- if pt initiates, tidal volume depends on muscular effort by pt
PEEP
- positive end expiratory pressure
- used to maintain open airways
- increased PEEP=worse the pt is
monitoring needs
for weaning
- ABGs
- Vitals
- S/Sx respiratory distress
