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

Goals of Mechanical Ventilation Normalization and maintenance of blood gases Normalization and maintenance of blood gases Prevention of iatrogenic complications Prevention of iatrogenic complications Support patient’s respiratory needs Support patient’s respiratory needs

ABG pH = paCO2 = mmHg paO2 = mmHg Avoid high O2 sats if delivering O2

Common terms PIP = Peak Inspiratory Pressure PIP = Peak Inspiratory Pressure Peep = Positive End Expiratory Pressure Peep = Positive End Expiratory Pressure Frequency = rate of ventilation (20 – 40 bpm) Frequency = rate of ventilation (20 – 40 bpm) I – time = Inspiratory time ( seconds) I – time = Inspiratory time ( seconds) MAP = Mean airway pressure MAP = Mean airway pressure Tidal Volume = amount of air inhaled in a single breath Tidal Volume = amount of air inhaled in a single breath Minute Ventilation Minute Ventilation

Neonatal Ventilation Time Cycled and Pressure Limited 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 patient’s airway during the inspiration –Initial values = cmH20 of PIP –Good chest rise and Good breath sounds

Neonatal Ventilation Peep = Positive pressure maintained in the patient’s airway during expiration Peep = Positive pressure maintained in the patient’s airway during expiration –Prevents collapsed alveoli –Increases FRC –Improves compliance –Improves oxygenation –Decreases intrapulmonary shunting –Allows for lower PIPs to be used

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

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

Most popular method High flow nasal cannula High flow nasal cannula

ET - CPAP in Pediatrics Pre and Post operatively to support structures Pre and Post operatively to support structures –Subglottic stenosis –Cleft palate –Laryngeal papillomas –Neck tumors –Tonsillitis –epiglottitis

Indications for NCPAP AARC Clinical Guidelines Increased WOB with retractions, flaring, grunting and cyanosis Increased WOB with retractions, flaring, grunting and cyanosis Inadequate ABG’s Inadequate ABG’s Presence of poor expansion on CXR Presence of poor expansion on CXR Presence of conditions responsive to CPAP Presence of conditions responsive to CPAP –RDS, Pulmonary edema, atelectasis, apnea, tracheal malacia, TTN

Contraindications to NCPAP Guidelines Upper airway abnormalities Upper airway abnormalities –TEF, choanal atresia Severe cardiovascular instability and impending arrest Severe cardiovascular instability and impending arrest Unstable respiratory drive Unstable respiratory drive Ventilatory failure Ventilatory failure

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

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

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

Flow rate Flow rate used determines the type of wave pattern Flow rate used determines the type of wave pattern Goal is to set flow to allow maximum diffusion time without causing turbulent flow 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

Indications for Vent Support Respiratory Failure Respiratory Failure –Hypoxemic respiratory failure PaO2 less than 50 on FIO2 greater than 60 PaO2 less than 50 on FIO2 greater than 60 –Hypercapnic respiratory failure PaCO2 greater than 50 and pH less than 7.25 PaCO2 greater than 50 and pH less than 7.25 –Mixed respiratory failure Both hypoxemia and hypercapnia Both hypoxemia and hypercapnia

Initial Setting on neonatal vent Time cycled – Pressure Limited ventilator 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 seconds for LBW and seconds for larger infants

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