Mechanical Ventilation

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Mechanical Ventilation

• Mary P. Martinasek BS, RRT
• Director of Clinical Education
• Hillsborough Community College

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Goals of Mechanical Ventilation

• Normalization and maintenance of blood gases
• Prevention of iatrogenic complications
• Support patients respiratory needs

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ABG

• pH 7.35 - 7.45
• paCO2 35 - 45 mmHg
• paO2 50 - 80 mmHg
• Avoid high O2 sats if delivering O2

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Common terms

• PIP Peak Inspiratory Pressure
• Peep Positive End Expiratory Pressure
• Frequency rate of ventilation (20 40 bpm)
• I time Inspiratory time (.2 - .8 seconds)
• MAP Mean airway pressure
• Tidal Volume amount of air inhaled in a single
  breath
• Minute Ventilation

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Neonatal Ventilation

• Time Cycled and Pressure Limited Ventilation
• Inspiration is stopped when the selected
  inspiratory time has been reached
• PIP is the maximum amount of pressure exerted on
  the patients airway during the inspiration
• Initial values 16-20 cmH20 of PIP
• Good chest rise and Good breath sounds

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Neonatal Ventilation

• Peep Positive pressure maintained in the
  patients airway during expiration
• Prevents collapsed alveoli
• Increases FRC
• Improves compliance
• Improves oxygenation
• Decreases intrapulmonary shunting
• Allows for lower PIPs to be used

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CPAP vs PEEP

• Same distending alveolar pressure
• PEEP is used in conjunction with ventilator rate
• CPAP is used in spontaneously breathing patient

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Methods of administering CPAP

• Endotracheal Tube
• Patent airway, airway clearance
• Disadvantage plugging, malacia, infection
• Nasal Prongs
• Decrease infection, no malacia
• Disadv. plugging,pressure necrosis, gastric
  distention
• Nasopharyngeal
• Pressure necrosis, infection
• Face Mask
• Temporary measure prior to intubation or for
  apnea episode

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Most popular method

• High flow nasal cannula

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ET - CPAP in Pediatrics

• Pre and Post operatively to support structures
• Subglottic stenosis
• Cleft palate
• Laryngeal papillomas
• Neck tumors
• Tonsillitis
• epiglottitis

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Indications for NCPAPAARC Clinical Guidelines

• Increased WOB with retractions, flaring, grunting
  and cyanosis
• Inadequate ABGs
• Presence of poor expansion on CXR
• Presence of conditions responsive to CPAP
• RDS, Pulmonary edema, atelectasis, apnea,
  tracheal malacia, TTN

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Contraindications to NCPAPGuidelines

• Upper airway abnormalities
• TEF, choanal atresia
• Severe cardiovascular instability and impending
  arrest
• Unstable respiratory drive
• Ventilatory failure

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Hazards of NCPAP

• Air leaks
• Ventilation Perfusion Mismatch
• CO2 retention and increased WOB
• Increase in PVR due to impedence of blood flow
• Nasal irritation with septal distortion
• Pressure necrosis
• Nasal mucosal damage due to inadequate
  humidification

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MAP

• Most powerful influence on oxygenation
• Average pressure exerted on the airway and lungs
  for the entire breath cycle
• Affected by PIP,PEEP,I-Time, Rate
• High levels can lead to decreased CO, pulmonary
  hypoperfusion and barotrauma

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Physiologic Deadspace

• Physiologic anatomic alveolar
• Anatomic Gas that fills the airways and never
  participates in gas exchange
• Alveolar gas that goes to unperfused alveoli
  and thus never participates in gas exchange
• Nl physiologic Vd in neonate 2cc/kg

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Flow rate

• Flow rate used determines the type of wave
  pattern
• Goal is to set flow to allow maximum diffusion
  time without causing turbulent flow
• Diffusion time is the length of time that the gas
  is in contact with the alveoli

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Indications for Vent Support

• Respiratory Failure
• Hypoxemic respiratory failure
• PaO2 less than 50 on FIO2 greater than 60
• Hypercapnic respiratory failure
• PaCO2 greater than 50 and pH less than 7.25
• Mixed respiratory failure
• Both hypoxemia and hypercapnia

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Initial Setting on neonatal vent

• Time cycled Pressure Limited ventilator
• PIP set 15 20 cm H20
• Peep set 3 5 cm H2O
• Rate set 20 40 bpm
• Flow set 6 8 lpm
• I time set .3 - .5 seconds for LBW and .5 - .8
  seconds for larger infants

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Settings

• PIP good chest excursion, good lung aeration
• Vt in pressure control PIP PEEP
• Vt in pressure control changes with change in
  compliance and resistance
• PIP set change only with changes in compliance
  and resistance in 2 cm increments

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