Chapter 17 Flashcards
Mechanical ventilation of the neonate and pediatric patient
What are the indications of Mechanical ventilation of the neonate and pediatric patient?
- Hypoxemic respiratory failure
- PaO2 < 50 on an FiO2 > 60% despite the use of CPAP - PaCO2 < 30 and pH > 7.25
- nasal flaring, grunting, retractions - Hypercapnic respiratory failure
- PaCO2 > 50 and pH < 7.25
- apneic, listless, cyanotic, bradycardic or tachycardic - Mixed also possible
- reversible problem exists - Causes
- neurological alteration
- impaired respiratory function
- impaired cardiovascular function post-op
- Pressure ventilation
- Pressure Control Ventilation (PCV)
- Time cycled, pressure limited
- Peak pressure set
- Variable flow
- Set Ti
- Set rate
- PEEP
- No direct control of Vt
- Volume Ventilation
- Traditional ventilation for adults
- Set Vt
- Set flow unless in PRVC
- Set Ti
- Set rate
- No control over peak pressures
- More susceptible to volume lost to tubing
- PRVC and VAPS two types of new breaths (listed under Dual Control)
- What are the Triggering, sensors at airway add deadspace and weight?
- Flow
- Pressure
- Motion, detects chest/abdominal movement
- Neural, detects diaphragm signals
- What are the Modes of ventilation?
- Full ventilatory support
- Continuous Mandatory Ventilation (CMV, A/C)
- All breaths are machine breaths, pt triggered or time triggered controls minute ventilation better
- may be pressure or volume breaths
- Volume: set tidal volume and rate
- Pressure: set peak pressure and rate
- PCV used for RDS, plateau pressure >35 or peak >40 - Synchronized Intermittent Mandatory Ventilation (SIMV) Mandatory breaths with spontaneous breaths in-between partial ventilation if rate below 30, full support if over 30 indicated if pt has apnea and needs a machine rate
Mandatory breaths are pressure or volume control ventilation: Spontaneous breaths are basically CPAP or PSV
avoids breath stackingPressure Control Inverse Ratio Ventilation (PCIRV)
- Pressure Control Inverse Ratio Ventilation (PCIRV)
- CMV or SIMV mode
- I time longer than E time
- pt needs to be paralyzed and sedated
- Used to improve oxygentation by raising mean airway pressure (MAP)
Pressure-Volume relationship
- Compliance
- stiff lungs cause low volumes with pressure ventilation
- Compliance curves
- volume pressure relationship
stiff lungs cause less volume with same pressures
over compliant lungs cause more volume with same pressures S shaped curve, see page 485
- volume pressure relationship
-Normal point B, good increase in volume with increase pressure Stiff point A, very little volume increase with pressure increase Overinflated lungs point C, little or no volume change with pressure
change
-Keep PEEP at inflection point, point A
do not use pressures that do not generate volume
- What are the Pressure-Volume relationship
- Compliance
- stiff lungs cause low volumes with pressure ventilation
- Compliance curves
- volume pressure relationship
stiff lungs cause less volume with same pressures
over compliant lungs cause more volume with same pressures S shaped curve, see page 485
- volume pressure relationship
-Normal point B, good increase in volume with increase pressure Stiff point A, very little volume increase with pressure increase Overinflated lungs point C, little or no volume change with pressure
change
-Keep PEEP at inflection point, point A
do not use pressures that do not generate volume
- What are the Pressure-Flow relationship?
- Not usually measured
but increase in Raw will decrease Vt factors that cause increased Raw
- bronchospasm (bronchodilator)
- Airway secretions (suction)
- Edema of airway walls (fluid balance)
- Inflammation (antibiotics, antiinflammatory) Artificial airway (Use largest possible)
- Setting the ventilator
Mode(infant)
- CPAP if oxygenation only problem (PaCO2 < 40)
- Low SIMV if spontaneous breathing (PaCO2 < 50)
- High SIMV or CMV if retaining CO2 (PaCO2 > 50)
- High frequency ventilation if no relief with above
(Other things to be done, surfactant replacement therapy, NO administration,
ECMO)
- Mode (pediatric)
- Much like adult only smaller Vt (6-8 ml/kg)
- CPAP if adequate CO2 (PaCO2 < 40)
- SIMV low rates if some breathing
- SIMV high rates or CMV if need more support
- Peak Inspiratory Pressure (PIP, PAP, Pmax, etc)
- Neonate 15-20 cmH2O
2. pediatric set to achieve desired Vt (see below)
- vSee table 17-2, page 313 for RR, Vt Ti, PEEP, FiO2 starting settings
- Rate
- neonate: start 40-60
- term: start 25-40
- pediatric: set to achieve desired CO2
- PEEP starts where?
- Start 5 cmH2O
- FiO2
- neonate: keep baby pink, use TCM or P-ox to keep within normal limits
- pediatric: PaO2 and/or SpO2 normal limits, 100% if needed for short times
- Where to start Inspiratory Time
- Low birth weight infants: 0.25 to 0.4
- Term infants: 0.3 - 0.5
- Pediatric: 0.6-1.2
- Comfort level also
- Where to start Tidal Volume
- Pressure control: result of pressure, airway resistance, and lung compliance
- Low birth weight 4-6 ml/kg
- Term5-8 ml/kg
- Pediatric 6-8 ml/kg
- I:E ratio
1:1.5 to 1:2
always check ratio when changing rate
- Recognizing Decreased compliance, stiff lungs
- Crackles
- Decreased chest wall excursion
- Decreased slope of pressure-volume loop
- Decreased tidal volume
- Recognizing Increased airway resistance
- Increased secretions
- Wheezes
- Reduced tidal volumes on same pressure
- May need to change parameters to maintain ABG’s
- Ventilator changes:
- Clinical signs of need for changes
- Breath sounds and chest excursion
2. Decreased air entry
- What are the Ventilator changes:
- Changing PaCO2
- Primary: rate, 2-5 bpm per change
- Secondary: Peak pressure, set by lung volume (watch returned volumes), watch chest excursion. Flow rate, increased flow increases Vt (watch returned volumes)
What are the Ventilator changes:
- Changing PaO2
- Primary: FiO2, up to 60%
- Secondary: increase mean airway pressure
- PEEP: 5cmH2O start, increase increments of 3-5 - - Increase I time
- Increase rate
- Complications of Mechanical ventilation of the neonate and pediatric patient?
- Overdistention
- Barotrauma
- Volutrauma
- Air leaks (pneumo: thorax, mediastinum, pericardium
- Tx decrease Vt, peak pressures, PEEP, chest tubes, permission hypercapnia (CO2 50-60 with pH >7.25)
- Set alarms carefully - Cardiovascular
Decreased CO
Increased PVR - Oxygen toxicity
Hypo or hyper ventilation
-Don’t forget assessment of chest excursion and CXR along with Vt and graphs
Weaning
- A plan to wean and extubate should be in place prior to intubation
The reason for the intubation and ventilation needs to have been resolved
Wean and extubation are two different levels
- Spontaneous breathing and adequate gas exchange
- Maintain airway patency and clear secretions
Wean infant What will be: FiO2 PEEP PIP Rate
- FiO2 wean to < 0.4-0.5
- PEEP wean by 1-2 increments to < 8cmH2O
- PIP wean by 1-2 to <30cmH2O
- Rate wean by 1-5 to <20 bpm
- What are the Signs of failure to wean?
- Tachycardia
- Bradycardia Pallor
- Retractions
- Hypercapnia
- Cyanosis
- Extubate if the above criteria met
- Hold feedings
- Tracheobronchial hygiene (Sx, CPT, Etc.)
- Air leak with positive breath, if no leak then Racemic Epinephrine first
- Hyperoxygenate
- Remove tape
- Manual ventilation and pull during breath
- What are the Post extubatio?
- Provide oxygen (hood, mask, cannula, nasal CPAP)
- Watch for failure
- CPT and reacemic epi tx
- Wean pediatric
- FiO2 < 40%
- PEEP < 5 cmH2O
- Rate to zero (CPAP) with or without PSV, take ETT size into account, see page 346
- Signs of failure to wean
- Increased WOB
- Atelectasis/increased secretions Agitation/dyspnea
- Respiratory muscle weakness
- Extubation
Success indicators
- Vt 3-4 ml/kg
- FiO2 < 30%
- MAP < 5 cmH2O
- Oxygen index (FiO2/PaO2) x 100 < 1.4
Leak test
- Suction oropharynx
- Deflate cuff
- Listen for leak with breath
- If no leak edema could be present, give racemic epi tx first
- Hyperoxygenate
- Suction ETT
- Remove tape
- Deflate cuff (if not done above) Manual breath and pull tube Administer O2
- Have pt cough
- High frequency ventilation
High Frequency Ventilation (HFV)
- small tidal volumes, even tidal volumes below anatomic dead space
- high rates 150- 3000 b/m
- uses lower peak pressures
- has not been proven to be significantly better than conventional ventilation use with surfactant therapy there is less BPD
- High Frequency Ventilation
Indications
- RDS when conventional ventilation (CV) fails airleaks/ pneumothorax
- PIE
- High Frequency Ventilation
Contraindications
- COPD
- non-homogenous lung disease
- leads to overdistension of good lung tissue
- High Frequency Ventilation
Hazards
- mucus plugging
- from lack of normal lung ventilation
- low Vt don’t move mucus 2. decreased CO - increased incidence of IVH
- Difficult to assess breath sounds and heart sounds
- Theory of how it works
High Frequency Ventilation
- flow goes down the inside of tube and out the outside of tube
- alveoli have different time constants and this mode inflates all alveoli better
- Types of
High-Frequency Jet Ventilation (HFJV)
4-11 Hz (240-660 b/m) Pulse of gas to airway - Special adaptor to ETT or special ETT - Triple lumen - One for jet bursts - One to measure pressure in lungs - One for CV
Jet draws in air around the jet
- Used in tandem with conventional ventilation
- Conventional vent supplies sighs for development of surfactant, PEEP, and continuous flow for the air entrained by the jet
- High-Frequency Oscillatory Ventilation (HFOV or HFO)
8-15 Hz
Piston or pump or diaphragm (loud speaker)
uses positive and negative pressure
Bias flow is driven into the ETT by the oscillator, expired air flows out with the same bias flow uses traditional ETT
can use with CV or spontaneously breathing pt
- HFJV, HFFI, HFOV
use what.
all use bias flow
like a “T” piece that acts as the source of the gas blown in with the bursts of gas allow for spontaneous breathing with the HFV
- Before placing pt on HFV
- get CXR
- give surfactant
- stabilize as much as possible so infant is not needing stimulation when first place on place monitors
- After placing on HFV
- Monitor CO and fluid balance
2. sedate
- SETTINGS HFJV
- start at 7Hz
- I time 0.2 seconds
- PIP at 90% or 10 above PIP on CV
- Reduce CV rate and Increase PEEP until Mean airway pressure same as CV may keep minimum CV rate to maintain CO2 and reduce atelectasis (ie 4bpm)
SETTINGS HFOV
- no gradual reduction of CV, just place on HFOV
- two strategies
Optimal Lung Volume Strategy (RDS) - 10 Hz for >750g, 15 Hz for < 750g
- Ti 33%
- Set mean airway pressure 1-2 higher than on CV, until PaO2 OK ∆P for adequate chest wall movement
Check CXR for adequate expansion (diaphragm at 8th or 9th rib)
- Adjusting settings HFOJV OR HFOV
- To decrease CO2 increase amplitude
- To increase O2 increase mean airway pressure (PEEP)
- Usually don’t adjust Hz
Wean
HFOJV AND HFOV
- Wean MAP in increments of 0.5 to 1.0, slowly
2. Wean as long as FiO2 remains under 0.30
DISEASES
Pulmonary Interstitial Emphysema (PIE)
- air dissects throughout the interstitial tissue of the lungs PIE caused by long term use of:
- High PIP
- PEEP
- prolonged inspiratory time - Pathology
- Interstitial air compresses small airways and vessels–> V/Q mismatch - Tx of mod to severe PIE
- Prevent
- Decreased pressures
- selective intubation of the unaffected lung
HFV
Pulmonary air embolism (rare)