Mechanical VentilationMechanical Ventilation

Mary P. Martinasek BS, RRTMary P. Martinasek BS, RRT

Director of Clinical EducationDirector of Clinical Education

Hillsborough Community Hillsborough Community CollegeCollege

Goals of Mechanical Goals of Mechanical VentilationVentilation

• Normalization and maintenance of Normalization and maintenance of blood gases blood gases

• Prevention of iatrogenic Prevention of iatrogenic complicationscomplications

• Support patient’s respiratory needsSupport patient’s respiratory needs

ABGABG

pH = 7.35 - 7.45pH = 7.35 - 7.45

paCO2 = 35 - 45 mmHgpaCO2 = 35 - 45 mmHg

paO2 = 50 - 80 mmHgpaO2 = 50 - 80 mmHg

Avoid high O2 sats if delivering O2Avoid high O2 sats if delivering O2

Common termsCommon terms

• PIP = Peak Inspiratory PressurePIP = Peak Inspiratory Pressure

• Peep = Positive End Expiratory PressurePeep = Positive End Expiratory Pressure

• Frequency = rate of ventilation (20 – 40 Frequency = rate of ventilation (20 – 40 bpm)bpm)

• I – time = Inspiratory time (.2 - .8 seconds)I – time = Inspiratory time (.2 - .8 seconds)

• MAP = Mean airway pressureMAP = Mean airway pressure

• Tidal Volume = amount of air inhaled in a Tidal Volume = amount of air inhaled in a single breath single breath

• Minute VentilationMinute Ventilation

Neonatal VentilationNeonatal Ventilation

• Time Cycled and Pressure Limited Time Cycled and Pressure Limited Ventilation Ventilation – Inspiration is stopped when the selected Inspiration is stopped when the selected

inspiratory time has been reachedinspiratory time has been reached– PIP is the maximum amount of pressure PIP is the maximum amount of pressure

exerted on the patient’s airway during exerted on the patient’s airway during the inspirationthe inspiration

– Initial values = 16-20 cmH20 of PIPInitial values = 16-20 cmH20 of PIP– Good chest rise and Good breath soundsGood chest rise and Good breath sounds

Neonatal VentilationNeonatal Ventilation

• Peep = Positive pressure maintained Peep = Positive pressure maintained in the patient’s airway during in the patient’s airway during expirationexpiration– Prevents collapsed alveoliPrevents collapsed alveoli– Increases FRCIncreases FRC– Improves complianceImproves compliance– Improves oxygenationImproves oxygenation– Decreases intrapulmonary shuntingDecreases intrapulmonary shunting– Allows for lower PIPs to be used Allows for lower PIPs to be used

CPAP vs PEEPCPAP vs PEEP

• Same distending alveolar pressureSame distending alveolar pressure

• PEEPPEEP is used in conjunction with is used in conjunction with ventilator rateventilator rate

• CPAPCPAP is used in spontaneously is used in spontaneously breathing patientbreathing patient

Methods of administering Methods of administering CPAPCPAP

• Endotracheal TubeEndotracheal Tube– Patent airway, airway clearancePatent airway, airway clearance– Disadvantage: plugging, malacia, infectionDisadvantage: plugging, malacia, infection

• Nasal ProngsNasal Prongs– Decrease infection, no malaciaDecrease infection, no malacia– Disadv. = plugging,pressure necrosis, gastric Disadv. = plugging,pressure necrosis, gastric

distentiondistention• NasopharyngealNasopharyngeal

– Pressure necrosis, infectionPressure necrosis, infection• Face MaskFace Mask

– Temporary measure prior to intubation or for Temporary measure prior to intubation or for apnea episodeapnea episode

Most popular methodMost popular method

• High flow nasal cannulaHigh flow nasal cannula

ET - CPAP in PediatricsET - CPAP in Pediatrics

• Pre and Post operatively to support Pre and Post operatively to support structuresstructures– Subglottic stenosisSubglottic stenosis– Cleft palateCleft palate– Laryngeal papillomasLaryngeal papillomas– Neck tumorsNeck tumors– TonsillitisTonsillitis– epiglottitisepiglottitis

Indications for NCPAPIndications for NCPAPAARC Clinical GuidelinesAARC Clinical Guidelines

• Increased WOB with retractions, Increased WOB with retractions, flaring, grunting and cyanosisflaring, grunting and cyanosis

• Inadequate ABG’sInadequate ABG’s

• Presence of poor expansion on CXRPresence of poor expansion on CXR

• Presence of conditions responsive to Presence of conditions responsive to CPAPCPAP– RDS, Pulmonary edema, atelectasis, RDS, Pulmonary edema, atelectasis,

apnea, tracheal malacia, TTNapnea, tracheal malacia, TTN

Contraindications to NCPAPContraindications to NCPAPGuidelinesGuidelines

• Upper airway abnormalitiesUpper airway abnormalities– TEF, choanal atresiaTEF, choanal atresia

• Severe cardiovascular instability and Severe cardiovascular instability and impending arrestimpending arrest

• Unstable respiratory driveUnstable respiratory drive

• Ventilatory failureVentilatory failure

Hazards of NCPAPHazards of NCPAP

• Air leaksAir leaks

• Ventilation Perfusion MismatchVentilation Perfusion Mismatch

• CO2 retention and increased WOBCO2 retention and increased WOB

• Increase in PVR due to impedence of blood Increase in PVR due to impedence of blood flowflow

• Nasal irritation with septal distortionNasal irritation with septal distortion

• Pressure necrosisPressure necrosis

• Nasal mucosal damage due to inadequate Nasal mucosal damage due to inadequate humidificationhumidification

MAPMAP

• Most powerful influence on oxygenationMost powerful influence on oxygenation

• Average pressure exerted on the airway Average pressure exerted on the airway and lungs for the entire breath cycleand lungs for the entire breath cycle

• Affected by: PIP,PEEP,I-Time, RateAffected by: PIP,PEEP,I-Time, Rate

• High levels can lead to decreased CO, High levels can lead to decreased CO, pulmonary hypoperfusion and pulmonary hypoperfusion and barotraumabarotrauma

Physiologic DeadspacePhysiologic Deadspace

• Physiologic = anatomic + alveolarPhysiologic = anatomic + alveolar

• Anatomic = Gas that fills the airways Anatomic = Gas that fills the airways and never participates in gas exchangeand never participates in gas exchange

• Alveolar = gas that goes to unperfused Alveolar = gas that goes to unperfused alveoli and thus never participates in alveoli and thus never participates in gas exchangegas exchange

• Nl physiologic Vd in neonate = 2cc/kgNl physiologic Vd in neonate = 2cc/kg

Flow rateFlow rate

• Flow rate used determines the type Flow rate used determines the type of wave pattern of wave pattern

• Goal is to set flow to allow maximum Goal is to set flow to allow maximum diffusion time without causing diffusion time without causing turbulent flowturbulent flow– Diffusion time is the length of time that Diffusion time is the length of time that

the gas is in contact with the alveolithe gas is in contact with the alveoli

Indications for Vent SupportIndications for Vent Support

• Respiratory FailureRespiratory Failure– Hypoxemic respiratory failureHypoxemic respiratory failure

•PaO2 less than 50 on FIO2 greater than 60 PaO2 less than 50 on FIO2 greater than 60

– Hypercapnic respiratory failureHypercapnic respiratory failure•PaCO2 greater than 50 and pH less than PaCO2 greater than 50 and pH less than

7.257.25

– Mixed respiratory failureMixed respiratory failure•Both hypoxemia and hypercapniaBoth hypoxemia and hypercapnia

Initial Setting on neonatal Initial Setting on neonatal ventvent

• Time cycled – Pressure Limited Time cycled – Pressure Limited ventilatorventilator– PIP set 15 – 20 cm H20PIP set 15 – 20 cm H20– Peep set 3 – 5 cm H2OPeep set 3 – 5 cm H2O– Rate set 20 – 40 bpmRate set 20 – 40 bpm– Flow set 6 – 8 lpmFlow set 6 – 8 lpm– I time set .3 - .5 seconds for LBW and .5 I time set .3 - .5 seconds for LBW and .5

- .8 seconds for larger infants- .8 seconds for larger infants

SettingsSettings

• PIP – good chest excursion, good PIP – good chest excursion, good lung aerationlung aeration

• Vt in pressure control = PIP – PEEPVt in pressure control = PIP – PEEP• Vt in pressure control changes with Vt in pressure control changes with

change in compliance and resistancechange in compliance and resistance• PIP set – change only with changes in PIP set – change only with changes in

compliance and resistance in 2 cm compliance and resistance in 2 cm incrementsincrements