Initial Ventilator Settings Flashcards
What are the types of ventilators and modes?
- Intubated vs mask
- ICU or home setting
- Brief or long term
What are the goals of ventilators and modes?
- Airway management
- Ventilation
- Oxygenation disturbance
What three things to consider for ventilation?
- Invasive vs non-invasive
- Volume vs pressure
- Full vs partial support
What three ways is non-invasive ventilation accomplished?
- NPV
- CPAP
- NPPV
What two ways may require the use of a face/nasal mask?
CPAP and NPPV
What are the general findings of negative pressure ventilators?
- NO AIRWAY!
- patient can talk, eat and drink
- avoid complications of PPV
- most often used in home - long term
- negative pressure across chest wall
In negative pressure ventilators, compliance and resistance must be ___
Stable
What kind of ventilation is good for patients who need night ventilation?
Negative pressure
What is negative pressure ventilation good for?
- Neuromuscular
- Kyphoscoliosis
- Chest wall deformity
- Spinal cord injuries
- Central control
- COPD at night
What must patients have for negative pressure ventilation?
- Airway protection
- Ability to swallow
- Normal compliance and resistance
What are the disadvantages of NPV?
- Patient access difficult
- May cause tank shock
- Not much control
- No spontaneous breathing
- Hot and noisy
- Not good for acute exacerbation of COPD
- No OSA - may exaggerate airway closure
How do you set a negative pressure ventilator?
- Set 5-10 below patient’s rate
- Increase negative pressure until patient can’t talk
- Max pressure of 35 can be achieved
- Use spirometer to measure volume
What things should you do when adjusting negative pressure ventilators?
- Adjust volume by increasing pressure or itime
- Ask patient how he feels
- Draw ABG to assess
What are the hazards of an iron lung?
- Abdominal pooling
- Large and cumbersome
- Nursing care difficult -IV
- Still used today
What is the chest curiass?
- Applies negative pressure to thorax
- Eliminates abdominal pooling
- Difficult to maintain a seal
What is a body wrap?
- Also called a pneumowrap, raincoat or poncho
- Made of nylon
- Not as efficient but popular because easy to use
What are the indications for NPPV?
- Patients with acute-on-chronic RF who require short term ventilation
- Terminally ill patients
- Patients who tolerate nasal/ask for long term
- Patients with ARF
What are the contraindications for NPPV?
- DNR orders
- Inability to clear secretions
- Inability to fit a mask
- Resp arrest - need for intubation
- Severe acidosis
- Shock Bp <90 mmHg
- Uncontrolled arrhythmias
- Uncooperative patient
- Upper airway obstruction/trauma
What is CPAP?
Keeps alveoli open and increases a PFT factor
When is CPAP used?
- Oxygenation
- Obstructive sleep apnea
- COPD with increase in WOB (be careful with COPD!)
When is NPPV for chronic RF used?
- Chest wall deformities
- Neuromuscular disorders
- Central alveolar hypoventilation
- COPD
- Cystic fibrosis
- Bronchiectasis
When is NPPV for acute RF used?
- COPD
- ARDS
- Pneumonia
- Asthma
- CF
- AIDS
- Heart failure
What are the advantages of NPPV?
- Avoids airway complication
- Flexibility in initiating and removing support
- Preserves airway defense
- Reduces need invasive monitoring
What are the disadvantages of NPPV?
- Cannot be used if aspiration risk
- Cannot be used for excessive secretions
- Cannot be used loss of protective airway reflexes
- Cannot be used in upper airway obstruction
- May not work ARF with oxygen deficit
- Causes gastric distension, skin press sores, facial pain, dry nose, eye irritation, poor sleep and discomfort
What are the overall goals of ventilation?
- Support the minute ventilation in order to meet the oxygen need
- Improve gas exchange
- Relieve respiratory distress
- Heal the lung
- Clear secretions
What is full ventilatory support (FVS)?
All work comes from the machine. High rates and minute volume
What is partial ventilatory support (PVS)?
Lowered mechanical work in hope that the patient will increase their breathing to compensate. Rates are less than 6/min and patient participates. Used in weaning
Which mode is better: pressure or volume?
No method has proved to be better than the another, it is usually an operator’s preference
Is pressure or volume control better for closed head injuries?
Volume because you get a guaranteed minute ventilation
What is controlled under volume control mode?
- Control volume
- Familiar
- Set VT, F and flow/itime
- Real risk of overdistension
- Good for iatrogenic hyperventilation in CHI
What is controlled under pressure control mode?
- Volume varies
- Set pressure, F and itime
- Set max pressure
- Reduce risk of overdistension
- Desc flow pattern improves distention of vent
- MAP rises with PV
What are the benefits of volume ventilation?
- Set volume, rate and flow (or itime)
- Guarantees a specific volume or MV
- Pressure varies with changes in compliance and resistance
- MV will be more controlled
What are the factors that affect pressure during volume ventilation?
- Patient’s lung characteristics
- Inspiratory flow patterns
- Volume setting
What can affect the patient’s lung characteristics?
Lower compliance or higher resistance results in higher peak and plateau pressures
What can affect the inspiratory flow patterns?
- Peak pressure higher with constant flow and lower with decreased flow
- High inspiratory flows create higher peak pressure
What is the ultimate goal of volume ventilation?
Minute ventilation that matches the patient’s metabolic needs
How would you calculate TCT?
- 60/F
- TI +TE
How would you calculate frequency?
MV / VT
How would you calculate itime?
(VT in L / flow) x 100
What is the Debois BSA equation for finding MV for men?
MV = 4 x BSA
What is the Debois BSA equation for finding MV for women?
MV = 3.5 x BSA
Why isn’t Debois BSA chart the most reliable?
It assumes normal conditions and must be changed in the face of:
- hypo/hyperthermia
- hypermetabolism
- metabolic acidosis
- burns
- lung diseases with increase VD
How do you determine VT?
- 8-10mL/kg IBW
- Rate of 12-18bpm
What should you keep the plateau pressure at to prevent alveolar distension?
< 30 cmH20
Use ___ VT with high peep levels
Lower
How do you calculate the volume lost in tubing?
Factor x PP
What pressure is the pressure gradient?
Driving pressure
How do you calculate IBW in men?
[106 + 6(H-60)] / 2.2
How do you calculate IBW in women?
[105 + 5(H-60)] / 2.2
What rates and VT would you select in a patient with normal lungs?
- Large VT (12)
- Low F (8-12)
- Flow to meet demand (40-100)
What rates and VT would you select in a patient with COPD lungs?
- High compliance and RAW
- Moderate VT (8-12)
- Low F (6-10)
- High flow to meet demand (40-100)
What rates and VT would you select in a patient with restrictive lungs?
- Smaller VT (<8-10)
- High F (12-20)
- Slower flow
Higher flow ___ itime and ___ PAP and causes poor gas distribution
Decresases; increases
Slower flow ___ i time and ___ PAP and improves gas distribution
Increase; decreases
How would you determine what flow and flow pattern to use?
- Set flow to meet patient demand
- ARDS may need 4 time constants
- COPD may need 3 time constants
True/False: flow too fast may worsen distribution in the lung and must be closely monitored
True
True/False: turbulent gas does not get to an alveolus
True
Describe the sine flow pattern
Better distention than constant. Paw and peak equal to constant. Peak higher when Raw is high
Describe the descending flow pattern
Occurs naturally in pressure ventilation. Peak pressure is lower than constant. Paw is higher. Descending improves distention of ventilation, decreases VD and improves oxygenation by increasing mean and plateau pressures
What are concerns associated with high peak and mean?
- Paw is more important than increased PIP
- Increased peak are not always associated lung injury
- When Raw is high peak pressure would be high but much of pressure is not dissipated in overcoming Raw and never reached the alveolar level
Changing the flow pattern may change what?
i time
In time-cycled hamiltons, servos and dragers, changing the flow pattern may change what?
Peak flow
In a VT/Flow cycled PB, changing the flow pattern changes what?
i time and I:E ratio
In waveforms, MAP ___ with descending flow and ___ with ascending flow
Increases; decreases
In waveforms, PIP ___ with descending flow and ___ with ascending flow
Decreases; increases
What does descending flow improve?
- Gas distribution
- Arterial oxygenation
What does it mean if PaO2 begins to decrease and PaCO2 rises while VE increases?
- Auto-peep
- poor V/Q non-homeogenous lung
- changes in venous return
- may need to change mode to spontaneous
When is an inflation hold used?
- Therapeutically
- Diagnostically
How is an inflation hold used therapeutically?
- Improves distribution of air exchange
- Reduces VD/VT
- Inverse I:E
How is an inflation hold used diagnostically?
Measures static pressure (compliance)
What must you do when setting a pressure level?
- Pressure grad bet PEEP (auto-peep) and PIP
- If switching measure plat and set pressure at plat
- Or set at 10 and increase
Why must you set a pressure limit when you set the pressure?
Safety alarm; in case the person coughs, etc
What are the goals of PSV?
- Increase VT
- Decrease RR
- Decrease WOB associated with art airway
PSV helps overcome __ to start a breath
Resistance
What is an indicator of adequate PSV?
Sternocleidomastoid muscle
How much pressure should you set with PSV?
- With lung Dx - usually 8-14 to overcome WOB
- Without lung Dx - about 5
What are set in PCV?
- Rate
- i time
- I:E ratio
- Pressure reviewed before
How should you set the sensitivity trigger?
Select lowest level to cycle without auto cycling
What are the 4 top reasons a machine will not cycle?
- Sensitivity set too low
- Auto-PEEP
- High bias flow
- Abdominal paradox
