Proper pressures in the DR Proper FiO2 in the DR (blended) Surfactant in the DR CPAP in the DR Consistent CPAP in the NICU Reduced SIMV in the NICU

‘‘Golden Hour’Golden Hour’ Lung Protective Strategy from Birth

good judgement

informed jugement

Neo-Puff in the DR

manual ventilation of

babies <30 weeks gest. Used for all transport

ventilation for all babies

easy to use, manually operatedgas-powered.

Neo-Puff Infant Resuscitator

Controlled and Precise Peak Inspiratory Pressure (PIP) The Neopuff™ Infant Resuscitator will inflate the baby’s lungs & provide optimum oxygenation by delivering consistent PIP with each breath, limiting the risks associated with under or over inflation at uncontrolled pressures.

Consistent and Precise Positive End Expiratory Pressure (PEEP) The Neopuff™ Infant Resuscitator maintains Functional Residual Capacity (FRC) by providing a consistent PEEP throughout the resuscitation process.

The desired PIP is set by turning the inspiratory pressure control.

The desired PEEP is set by adjusting the T-piece aperture.

Pressure/Volume

Over Weaning damages too

Ventilator-Associated Lung Injury

Barotrauma (air leak) Oxygen toxicity Ventilator associated pneumonia Over-distention De-recruitment

Slutsky and Tremblay Slutsky and Tremblay Am J Respir Crit Care Med Am J Respir Crit Care Med 1998; 157: 1721-17251998; 157: 1721-1725MOSF Death

•Shear•Overdistention•Cyclic stretch•Inc. intrathoracic pressure

•Inc alveolar cap permeability•Dec cardiac output•Dec organ perfusion

•Tissue injury secondary to•Inflamatory mediators/cells•Impaired O2 delivery•bacteremia

Cytokines, prostanoids,

Leukotrienes, reactive oxygen species,

protease

neutrophil

Distal Organs

Biochemical Injury Biophysical Injury

Dreyfuss, Am J Respir Crit Care Med 1998;157:294-323Dreyfuss, Am J Respir Crit Care Med 1998;157:294-323

normallungs

5 min of 45 cm H2O

20 min of 45 cm H2O

Webb and Tierney, Am Rev Respir Dis 1974; 110:556-565Webb and Tierney, Am Rev Respir Dis 1974; 110:556-565

14/0 45/10 45/0

esophagealintubation

Pulmonary Interstitial Emphesema to Pneumo-

Assessment

•Chest x-ray AP• 8 rib conventional• 9-10 rib Hi-Fi•Rise & fall of chest (slight per NRP)•Listen to breath sounds•Vt 5-7 ml/kg (3-5 spont.)•follow ABGs

P ressu re

T im e

Pressure WavePressure Wave

To Increase Mean Airway Pressure

1. Increase flow

2. Increase peak pressure

3. Lengthen inspiratory time

4. Increase PEEP

5. Increase Rate

TYPES OF MECHANICAL VENTILATION

negative pressure ventilation positive pressure ventilation high-frequency ventilation non-invasive positive pressure ventilation

Body Box:Body Box:

OutlineOutline Respiratory mechanics and gas exchangeRespiratory mechanics and gas exchange Factors affecting oxygenation and carbon dioxide Factors affecting oxygenation and carbon dioxide

elimination during mechanical ventilationelimination during mechanical ventilation Blood gas analysisBlood gas analysis Ventilatory management: basics and specificsVentilatory management: basics and specifics High frequency ventilation: the basicsHigh frequency ventilation: the basics

OverviewOverview Mechanical ventilation is an integral part of Mechanical ventilation is an integral part of

neonatal intensive care, and has led to increased neonatal intensive care, and has led to increased survival of neonates over the last 3 decadessurvival of neonates over the last 3 decades

Advances in knowledge of neonatal respiratory Advances in knowledge of neonatal respiratory physiology have led to optimization of techniques physiology have led to optimization of techniques and strategiesand strategies

Conventional mechanical ventilation (CMV) is Conventional mechanical ventilation (CMV) is most often used, despite the advent of HFV and most often used, despite the advent of HFV and SIMVSIMV

OverviewOverview Respiratory failure in neonates has significant Respiratory failure in neonates has significant

morbidity and mortality (although less than in the morbidity and mortality (although less than in the past)past)

Optimal ventilatory management will reduce the Optimal ventilatory management will reduce the risk of chronic lung diseaserisk of chronic lung disease

Optimal ventilatory management should be Optimal ventilatory management should be individualized and be based upon the individualized and be based upon the pathophysiology and certain basic concepts of pathophysiology and certain basic concepts of mechanical ventilationmechanical ventilation

ConceptsConcepts Goal of mechanical ventilationGoal of mechanical ventilation: to improve gas : to improve gas

exchange and to sustain life without inducing lung exchange and to sustain life without inducing lung injuryinjury

Factors that should influence ventilator adjustment Factors that should influence ventilator adjustment decisions:decisions: Pulmonary mechanicsPulmonary mechanics Gas exchangeGas exchange Control of breathingControl of breathing Lung injuryLung injury

Pulmonary mechanicsPulmonary mechanics ComplianceCompliance

Property of distensibility of the lungs and chest wallProperty of distensibility of the lungs and chest wall Change in volume per unit change in pressureChange in volume per unit change in pressure C = C = VolumeVolume

PressurePressure Neonatal lung Neonatal lung

Normal Normal 0.003-0.0060.003-0.006 L/cm H L/cm H22OO

with RDS with RDS 0.0005-0.0010.0005-0.001 L/cm H L/cm H22OO

Pulmonary mechanicsPulmonary mechanics Resistance:Resistance:

inherent capacity of the air conducting system (airways inherent capacity of the air conducting system (airways and ETT) and tissues to resist airflowand ETT) and tissues to resist airflow

Change in pressure per unit change in flowChange in pressure per unit change in flow R = R = Pressure Pressure

FlowFlow

Total cross-sectional Total cross-sectional areaarea of airways of airways

ResistanceResistance LengthLength of the airways of the airways

FlowFlow rate rate

DensityDensity and and viscosity viscosity of gasof gas

Pulmonary mechanicsPulmonary mechanics Location of airway resistance:Location of airway resistance:

0 5 10 15 200 5 10 15 20

Distal airways contribute less to resistance due to Distal airways contribute less to resistance due to increased total cross-sectional areaincreased total cross-sectional area

Small ETT and high flow rates can increase Small ETT and high flow rates can increase resistance markedlyresistance markedly

ResistanceResistance

Airway GenerationAirway Generation

Distal -->

Pulmonary mechanicsPulmonary mechanics Laminar flowLaminar flow (Distal airways) (Distal airways)

Driving pressure proportional to flow Driving pressure proportional to flow R= R= 8 n l8 n l (n = viscosity ; l = length; r = radius) (n = viscosity ; l = length; r = radius)

rr44

Turbulent flowTurbulent flow (Proximal airways) (Proximal airways) Driving pressure proportional to square of flow Driving pressure proportional to square of flow Reynolds number (Re) = Reynolds number (Re) = 2 r V d2 r V d (d = density) (d = density)

nn

Pulmonary mechanicsPulmonary mechanics A pressure gradient between the upper airway and A pressure gradient between the upper airway and

alveoli is necessary for gas flow during inspiration alveoli is necessary for gas flow during inspiration and expirationand expiration

The pressure gradient is required to overcome the The pressure gradient is required to overcome the elasticity, resistance, and inertance of the elasticity, resistance, and inertance of the respiratory systemrespiratory system

Equation of motion: Equation of motion: P = P = 1 1 V + R V + I V V + R V + I V CC

Elasticity+Resistance+Inertance

Pulmonary mechanicsPulmonary mechanics

Time constant Time constant The time taken for the airway pressure (and The time taken for the airway pressure (and

volume) changes to equilibrate throughout the volume) changes to equilibrate throughout the lung is proportional to the compliance and lung is proportional to the compliance and resistance of the respiratory systemresistance of the respiratory system

Time constant = Compliance x ResistanceTime constant = Compliance x Resistance

Pulmonary mechanicsPulmonary mechanics % change in pressure in relation to time% change in pressure in relation to time

Almost full equilibration: 3-5 time constantsAlmost full equilibration: 3-5 time constants

100

80

60

40

20

01 2 3 4 5 Time constants

C

hang

e in

pre

ssur

e (%

)63

8695 98 99

Pulmonary mechanicsPulmonary mechanics Healthy term neonate:Healthy term neonate:

C = 0.004 L/cm HC = 0.004 L/cm H22O; R = 30 cm HO; R = 30 cm H22O/L/secO/L/sec

T = 0.004 x 30 = 0.12 secT = 0.004 x 30 = 0.12 sec Time constants Time (sec) % equilibrationTime constants Time (sec) % equilibration

11 0.120.12 6363

22 0.240.24 8686

33 0.360.36 9595

55 0.600.60 9999

RDS: Shorter time constantRDS: Shorter time constant

Pulmonary mechanicsPulmonary mechanics Application of the concept of time constantApplication of the concept of time constant

Short TShort TII : decreased tidal volume delivery : decreased tidal volume delivery

Inadequate TInadequate TEE: Gas trapping ( FRC, inadvertent : Gas trapping ( FRC, inadvertent

PEEP)PEEP)Heterogeneous lung diseaseHeterogeneous lung disease (BPD): different (BPD): different

regions of the lung have different time constants; regions of the lung have different time constants; tendency for atelectasis and hyperexpansion to co-tendency for atelectasis and hyperexpansion to co-existexist

Gas exchangeGas exchange Total minute ventilation = tidal vol x freqTotal minute ventilation = tidal vol x freq

VVEE = V = VTT x f x f

Alveolar ventilation (Alveolar ventilation (VVAA) = Useful (fresh gas) portion ) = Useful (fresh gas) portion of minute ventilation that reaches gas exchange units; of minute ventilation that reaches gas exchange units; excludes dead space (excludes dead space (VVDD)) VVAA = (V = (VTT-V-VDD) x f) x f

Alveolar ventilation equation:Alveolar ventilation equation:

VVAA (L/min) = V (L/min) = VCO2CO2 (ml/min) x 0.863 (BTPS (ml/min) x 0.863 (BTPS

P PAACO2 CO2 (mm Hg) corr.)(mm Hg) corr.)

Gas exchangeGas exchange Alveolar gas equation:Alveolar gas equation:

If R=1, each molecule of OIf R=1, each molecule of O22 removed from alveoli is removed from alveoli is

replaced by one molecule of COreplaced by one molecule of CO22

PPAAO2O2 = = PPIIO2O2 - - PPAACO2CO2

Average normal value for R = 0.8Average normal value for R = 0.8

PPAAO2O2 = = F FIIO2O2 x (P x (PBB-P-PH2OH2O)) - P- PAACO2CO2x x FFIIO2+ O2+ 1- 1- FFIIO2O2

RR

PaPaCO2CO2 = effective P = effective PAACO2CO2 True PTrue PAACO2CO2 = P = PETETCO2CO2

Gas exchangeGas exchange Ventilation-Perfusion matching:Ventilation-Perfusion matching:

matching of gas flow and blood flow required for matching of gas flow and blood flow required for successful gas exchangesuccessful gas exchange VVAA = = Alveolar ventilationAlveolar ventilation

Q Pulmonary blood flow (Fick method: OQ Pulmonary blood flow (Fick method: O22))

= 0.863 x R x (Ca= 0.863 x R x (CaO2O2 - C - CVVO2O2))

PPAACO2CO2

V/Q mismatching usually relevant to effect on V/Q mismatching usually relevant to effect on alveolar-arterial Palveolar-arterial PO2O2 difference: (A-a) difference: (A-a)PPO2O2

Gas exchangeGas exchange OO22-CO-CO22 diagram diagram

40 60 80 100 120 140 160

020

4060

PCO2

P O2 (mm Hg)

V/Q = 8 I

V/Q = 0

0.21.0 1.5

0.5

IdealV/Q = 0.84

v

Gas exchangeGas exchange Causes of hypoxemiaCauses of hypoxemia

V/Q mismatchV/Q mismatch Right to left shunt (venous admixture)Right to left shunt (venous admixture) Hypoventilation (e.g. in apnea)Hypoventilation (e.g. in apnea) Diffusion abnormalitiesDiffusion abnormalities

Causes of hypercapniaCauses of hypercapnia HypoventilationHypoventilation Severe V/Q mismatchSevere V/Q mismatch

Gas exchangeGas exchange

Factors involved in gas exchange during Factors involved in gas exchange during mechanical ventilationmechanical ventilationOxygenationOxygenationCarbon dioxide eliminationCarbon dioxide eliminationGas transport mechanismsGas transport mechanismsPatient - ventilator interactionsPatient - ventilator interactions

Gas exchangeGas exchange

Factors affecting oxygenationFactors affecting oxygenation Mean airway pressure (Mean airway pressure (MAPMAP)) : affects V/Q : affects V/Q

matching. matching. MAP MAP is theis the average airway pressure average airway pressure during respiratory cycleduring respiratory cycle

MAP = K (PIP-PEEP) [TMAP = K (PIP-PEEP) [TI I / (T/ (TII+T+TEE)] + PEEP)] + PEEP

Oxygen concentration of inspired gas (Oxygen concentration of inspired gas (FFIIO2O2))

Gas exchangeGas exchange MAP increases with increasing PIP, PEEP, MAP increases with increasing PIP, PEEP,

TTII to T to TEE ratio, rate, and flow ratio, rate, and flow

PEEP

PIP

TI

RateFlow

Pressure

TimeTI TE

PEEP

PIP

Gas exchangeGas exchange Relation of MAP to PaRelation of MAP to PaOO22 not linear; is like an not linear; is like an

inverted “U”: inverted “U”: Low MAP:Low MAP:

AtelectasisAtelectasis-->--> very low Pavery low PaOO22

High MAP:High MAP: hyperinflationhyperinflation--> V/Q mismatch; intrapulmonary --> V/Q mismatch; intrapulmonary

shunt, hypoventilation due to distended alveolishunt, hypoventilation due to distended alveoli decreased cardiac outputdecreased cardiac output --> decreased oxygen --> decreased oxygen

transport despite adequate Patransport despite adequate PaOO22

Gas exchangeGas exchange For the same change in MAP, changes in PIP For the same change in MAP, changes in PIP

and PEEP improve oxygenation more than and PEEP improve oxygenation more than changes in I:E ratiochanges in I:E ratio

Reversed I:E ratios increase risk of air-trapping Reversed I:E ratios increase risk of air-trapping PEEP levels higher than 6 cm HPEEP levels higher than 6 cm H22O may not O may not

improve oxygenation in neonatesimprove oxygenation in neonates Attainment of optimal MAP may allow Attainment of optimal MAP may allow

weaning of Fweaning of FIIO2O2 Atelectasis may lead to sudden increase in Atelectasis may lead to sudden increase in

required Frequired FIIO2O2

Gas exchangeGas exchange Carbon dioxide eliminationCarbon dioxide elimination

Proportional to Proportional to alveolar ventilationalveolar ventilation (V (VAA) which depends ) which depends on on tidal volumetidal volume (V (VTT) and ) and frequencyfrequency (rate) (rate)

VVTT changes more effective (but more barotrauma) : dead changes more effective (but more barotrauma) : dead space constant, so proportion of Vspace constant, so proportion of VTT that is alveolar that is alveolar ventilation increases to a greater degree with increases in ventilation increases to a greater degree with increases in VVTT

VVTT 4 --> 6cc/kg (50% ) with dead space of 2 cc/kg 4 --> 6cc/kg (50% ) with dead space of 2 cc/kg increases Vincreases VAA from 2 (4-2) to 4 (6-2) cc/kg/breath from 2 (4-2) to 4 (6-2) cc/kg/breath (100% )(100% )

Gas exchangeGas exchange Clinical estimation of optimal TClinical estimation of optimal TI I and Tand TEE::

Short TI Optimal TI Long TI

Inadeq VT Short insp. plateau Long plateau

Short TE Optimal TE Long TEAir trapping Short exp. plateau Long exp. plateau

ChestWallMotion

Time

ChestWallMotion

Gas exchangeGas exchange Synchrony vs. Asynchrony Synchrony vs. Asynchrony ++ “fighting” “fighting”

Synchrony augments ventilation, improves Synchrony augments ventilation, improves COCO22 elimination, decreases hypoxic elimination, decreases hypoxic episodesepisodes

Asynchrony leads to poor tidal volume Asynchrony leads to poor tidal volume delivery, and impairs gas exchangedelivery, and impairs gas exchange

Active exhalation (exhalation during Active exhalation (exhalation during ventilator breath) increases risk of hypoxic ventilator breath) increases risk of hypoxic episodesepisodes

Blood gas analysisBlood gas analysis Arterial blood gas analysis the “Arterial blood gas analysis the “gold standardgold standard”” Interpretation:Interpretation:

pH: Is it normal, acidotic, or alkalotic?pH: Is it normal, acidotic, or alkalotic? PPCOCO22: Is it normal, (respiratory acidosis), or : Is it normal, (respiratory acidosis), or

(respiratory alkalosis)?(respiratory alkalosis)? HCOHCO33: Is it normal, (metabolic acidosis), or : Is it normal, (metabolic acidosis), or

(metabolic alkalosis)?(metabolic alkalosis)? Simple disorder or mixed? Compensated or not?Simple disorder or mixed? Compensated or not? PPOO22: Normal, hypoxia, or hyperoxia?: Normal, hypoxia, or hyperoxia?

Blood gas analysisBlood gas analysis Normal values Normal values (1 hr age, not ventilated)(1 hr age, not ventilated)

Preterm: Preterm: pHpH 7.28-7.32, 7.28-7.32, PPCOCO22 35-45, 35-45, PPOO22 50-80 50-80

Term: Term: pH pH 7.30-7.35, 7.30-7.35, PPCOCO22 35-45, 35-45, PPOO22 80-95 80-95

Target valuesTarget values RDS: RDS: pHpH >> 7.25, 7.25, PPCOCO22 45-55, 45-55, PPOO22 50-70 50-70

BPD: BPD: pHpH >> 7.25, 7.25, PPCOCO22 45-70, 45-70, PPOO22 60-80 60-80

PPHN: PPHN: pHpH 7.50-7.60, 7.50-7.60, PPCOCO22 25-40, 25-40, PPOO22 80-120 80-120

Remember! ORemember! O22 content determined mostly by SpO content determined mostly by SpO22 and and

Hb%. Hb%.

Blood gas analysisBlood gas analysis Common errors:Common errors:

Infrequent ventilator adjustmentsInfrequent ventilator adjustments made only made only when ABG (q4/q6) is obtained. In acute phase of when ABG (q4/q6) is obtained. In acute phase of RDS or PPHN, adjustments should be made with RDS or PPHN, adjustments should be made with chest rise, SpOchest rise, SpO22, TcP, TcPOO22/P/PCOCO22 trends trends

Room air contamination:Room air contamination: P PCOCO22, P, POO22(if <150 (if <150 torr ). Amount in butterfly set sufficient !torr ). Amount in butterfly set sufficient !

Liquid heparin /saline contamination:Liquid heparin /saline contamination: pH same, pH same, but lower Pbut lower PCOCO22 (mimics compensated metabolic (mimics compensated metabolic acidosis)acidosis)

Ventilatory managementVentilatory management Indications:Indications:

Clinical:Clinical: Absolute:Absolute: Apnea (intractable), gasping, Apnea (intractable), gasping, cyanosis not responsive to Ocyanosis not responsive to O22 by hood by hood

Relative:Relative: Severe tachypnea / retractions Severe tachypnea / retractions Laboratory (while on CPAP or FiOLaboratory (while on CPAP or FiO22 > 0.7): > 0.7):

pHpH << 7.25 with 7.25 with PPCOCO22 > 60 > 60

(or) (or) PPOO22 < 45- 50 and / or SpO < 45- 50 and / or SpO22 < 85 < 85 Other:Other: Surgical procedures, compromised airway Surgical procedures, compromised airway

Ventilator settingsVentilator settings PIP:PIP:

affects MAP (affects MAP (PPOO22) and V) and VTT ( (PPCOCO22)) PIP required depends largely on compliance of PIP required depends largely on compliance of

respiratory systemrespiratory system Clinical: gentle rise of chest with breath, similar Clinical: gentle rise of chest with breath, similar

to spontaneous breathto spontaneous breath Minimum effective PIP to be usedMinimum effective PIP to be used. No relation . No relation

to weight or airway resistanceto weight or airway resistance Neonate with RDS: 15-30 cm HNeonate with RDS: 15-30 cm H22O. Start low O. Start low

and increase.and increase.

Ventilator settingsVentilator settings PEEP:PEEP:

affects MAP (affects MAP (PPOO22), affects V), affects VTT ( (PPCOCO22) depending on ) depending on

position on P-V curveposition on P-V curve

older infants (e.g. BPD) tolerate higher levels of PEEP older infants (e.g. BPD) tolerate higher levels of PEEP (6-8 cm H(6-8 cm H22O) betterO) better

RDS: minimum 2-3, maximum 6 cm HRDS: minimum 2-3, maximum 6 cm H22O. O.

Pressure

Volume

PEEP PIP

Ventilator settingsVentilator settings Rate:Rate:

affects minute ventilation (affects minute ventilation (PPCOCO22)) In general, rate ---> In general, rate ---> PPCOCO22

Rate changes alone do not alter MAP (with Rate changes alone do not alter MAP (with constant I:E ratio) or change constant I:E ratio) or change PPOO22 , unless PVR , unless PVR changes with changes in pHchanges with changes in pH

However, iHowever, if rate --> Tf rate --> TEE < 3TC --> gas < 3TC --> gas trapping--> decreased Vtrapping--> decreased VTT--> --> PPCOCO22

Minute ventilation plateaus, then falls with rateMinute ventilation plateaus, then falls with rate

Ventilator settingsVentilator settings TTII and T and TEE::

Need to be 3-5 TC for complete inspiration and Need to be 3-5 TC for complete inspiration and expiration (Note: TC exp = TC insp)expiration (Note: TC exp = TC insp)

Usual ranges:Usual ranges: T TII sec sec TTEE secsec RDS RDS 0.2-0.45 0.2-0.45 0.4-0.6 0.4-0.6 BPDBPD 0.4-0.8 0.4-0.8 0.5-1.50.5-1.5 PPHNPPHN 0.3-0.8 0.3-0.8 0.5-1.00.5-1.0

Chest wall motion / VChest wall motion / VTT may be useful in may be useful in determining optimal Tdetermining optimal TII and T and TEE

Ventilator settingsVentilator settings I : E RatioI : E Ratio

When corrected for the same MAP, changes in When corrected for the same MAP, changes in I:E ratio do not affect gas exchange as much as I:E ratio do not affect gas exchange as much as changes in PIP or PEEPchanges in PIP or PEEP

Changes in TChanges in TII or T or TEE do not change V do not change VTT or P or PCOCO2 2

unless they are too short (< 3 TC)unless they are too short (< 3 TC) Reversed I:E ratio: No change in mortality or Reversed I:E ratio: No change in mortality or

morbidity noted in studies. Not often used. morbidity noted in studies. Not often used. May improve V/Q matching and PMay improve V/Q matching and POO22 at risk of at risk of venous return and gas trapping venous return and gas trapping

Ventilator settingsVentilator settings FiFiO2O2

affects oxygenation directlyaffects oxygenation directly with Fiwith FiO2O2 <0.6-0.7, risk of oxygen toxicity less than <0.6-0.7, risk of oxygen toxicity less than

risk of barotraumarisk of barotrauma to improve oxygenation, increase Fito improve oxygenation, increase FiO2O2 to 0.7 before to 0.7 before

increasing MAPincreasing MAP during weaning, once PIP is low enough, reduce during weaning, once PIP is low enough, reduce

FiFiO2O2 from 0.7 to 0.4. Maintenance of adequate MAP from 0.7 to 0.4. Maintenance of adequate MAP and V/Q matching may permit a reduction in Fiand V/Q matching may permit a reduction in FiO2O2

Ventilator settingsVentilator settings Flow:Flow:

affects pressure waveformaffects pressure waveform minimal effect on gas exchangeminimal effect on gas exchange as long as as long as

sufficient flow usedsufficient flow used increased flow--> turbulenceincreased flow--> turbulence higher flow required if TI short, to maintain higher flow required if TI short, to maintain

TVTV flow of 8-10 lpm usually sufficientflow of 8-10 lpm usually sufficient change of flow may affect delivery of NO or change of flow may affect delivery of NO or

anesthesia gasesanesthesia gases

Ventilatory managementVentilatory management RDS:RDS:

Pathology: decreased compliance, FRCPathology: decreased compliance, FRC Once diagnosis established, and if POnce diagnosis established, and if PO2O2<50 on 40% <50 on 40%

oxygen: CPAP (or) early intubation and surfactant. oxygen: CPAP (or) early intubation and surfactant. (Prophylactic CPAP for ELBW(Prophylactic CPAP for ELBW not not useful)useful)

Ventilation if FiVentilation if FiO2O2 > 0.7 required on CPAP > 0.7 required on CPAP Surfactant q 6 hrs if intubated and FiSurfactant q 6 hrs if intubated and FiO2O2 > 0.3-0.4 > 0.3-0.4

(Survanta / Infasurf / Curosurf better than (Survanta / Infasurf / Curosurf better than Exosurf). Usually 1-2, rarely 4 doses required.Exosurf). Usually 1-2, rarely 4 doses required.

Ventilatory managementVentilatory management RDS (continued):RDS (continued):

Use Use lowest PIPlowest PIP required required moderate PEEPmoderate PEEP (4-5 cm H (4-5 cm H22O)O) permissive hypercarbiapermissive hypercarbia (Pa (PaCO2CO2 45-55 mmHg 45-55 mmHg

instead of 35-45 is safe, and need for instead of 35-45 is safe, and need for ventilation in first 4 days)ventilation in first 4 days)

limited use of paralysis, limited use of paralysis, aggressive weaningaggressive weaning chest PT not useful, maybe dangerous in chest PT not useful, maybe dangerous in

acute phase (increases IVH)acute phase (increases IVH)

Ventilatory managementVentilatory management Chronic lung disease / BPD:Chronic lung disease / BPD:

usually heterogeneous lung disease - different usually heterogeneous lung disease - different areas of lung with different time constantsareas of lung with different time constants

increased resistance, frequent exacerbationsincreased resistance, frequent exacerbations higher PEEPhigher PEEP often helpful (4-7 cm H often helpful (4-7 cm H22O)O) longer Tlonger TII and T and TEE, with low rates, with low rates hypercarbia and compensated respiratory hypercarbia and compensated respiratory

acidosis often tolerated to avoid increased acidosis often tolerated to avoid increased lung injurylung injury

Ventilatory managementVentilatory management PPHN:PPHN:

ventilator management controversialventilator management controversial FiFiO2O2 adjusted to maintain adjusted to maintain PaPaO2O2 80-100 80-100 to to

minimize hypoxia-mediated pulmonary minimize hypoxia-mediated pulmonary vasoconstrictionvasoconstriction

ventilatory rates and pressures adjusted to ventilatory rates and pressures adjusted to maintain maintain mild alkalosismild alkalosis (pH 7.5-7.6), usually (pH 7.5-7.6), usually combined with bicarbonate infusioncombined with bicarbonate infusion

avoid low Paavoid low PaCO2CO2 (<20 mm Hg) (<20 mm Hg) to prevent to prevent cerebral vasoconstrictioncerebral vasoconstriction

Volume GuaranteeThe ventilator automatically adjusts the inspiratory pressure according to changes of compliance, resistance or

respiratory drive.

Pressure Support VentilationWorking Principle of Breath

Termination

Erin Browne

Flow SensorMeasurement Principle

Two tiny platinum wires are heated to 400°C

Gas flow cools the wire down

From the amount of cooling the amount of gas flowing can be calculated

T = 400°C

no gas flow

with gas flow

Endotracheal Tube Leak

Lung Function MonitoringClinical Applications

Identification of Lung Overdistention Prediction of successful extubation Prediction of risk of BPD development Response to Surfactant or Brochodilators Teaching tool Titration of optimal PEEP Trend in development of disease Check of compliance during HFV recognition of recovery from suctioning

OSCILLATOR

High frequency ventilationHigh frequency ventilation TechniquesTechniques

HFPPV HFJVHFPPV HFJV HFFI HFFI HFOVHFOV

VVTT >dead sp>dead sp > or > or < ds< ds > or > or <ds<ds <ds<dsExpExp passive passive passive passive passive passive activeactiveWave- variableWave- variable triangular triangular triangular triangular sine wavesine waveformformEntrai- noneEntrai- none possiblepossible none none nonenonementmentFreq.Freq. 60-150 60-150 60-600 60-600 300-900 300-900 300-3000 300-3000

(/min)(/min)

High frequency ventilationHigh frequency ventilation HFPPV

conventional ventilators with low-compliance tubing

ventilatory rates of 60-150/minnot very effective: minute ventilation

decreases with high frequenciesventilator and circuit design are not optimal

for use at frequencies

High frequency ventilationHigh frequency ventilation HFJV (e.g. Bunnell Life Pulse HFJV)

adequate gas exchange with lower MAPServo pressure reflects volume ventilated:

increases with improving compliance or resistance or by peri-ET leaks

decreased by worsening compliance, resistance, obstruction, or pneumothorax

Larger babies: 300 bpm; smaller ones: 500 bpm

High frequency ventilationHigh frequency ventilation HFJV (contd.)HFJV (contd.)

MAP controls PaO2, P (and frequency) control PaCO2. (MAP controls lung volume. PaO2 will not respond to increased MAP if FRC normal)

smaller TV (P) with higher PEEP better than larger TV with lower PEEP (--> hypoxia with hypocarbia)

Optimal PEEP: no drop in SpO2 when CMV off Parallel conventional ventilation recruits alveoli (use

low rate : 1-3 bpm; 0-1 bpm if air leak)

High frequency ventilationHigh frequency ventilation HFOV (e.g. Sensormedics 3100A)

Generally used at more MAP than CMV; optimal MAP difficult to determine as CXR “rib space counting” not very accurate

Frequency: 5-10 Hz better for CO2 elimination; 10-15 Hz better for improving oxygenation

maybe useful in airleak syndromes maybe useful in PPHN; may decrease need for

ECMO esp. if combined with NO

High frequency ventilationHigh frequency ventilation HFFI (e.g. Infant Star with HFFI module)HFFI (e.g. Infant Star with HFFI module)

active expiration in Infant Star model active expiration in Infant Star model makes operation more like HFOVmakes operation more like HFOV

clinical studies have not shown it to be clinical studies have not shown it to be superior to conventional ventilationsuperior to conventional ventilation

more convenient: single ventilator for more convenient: single ventilator for CMV and HFV makes initiation and CMV and HFV makes initiation and weaning easierweaning easier

High frequency ventilationHigh frequency ventilation Uses of HFOV/ HFJV/ HFFI :Uses of HFOV/ HFJV/ HFFI :

““rescue” rescue” for severe RDSfor severe RDS air leak syndromes (pneumothorax, PIE)air leak syndromes (pneumothorax, PIE) PPHNPPHN

Primary use controversial:Primary use controversial: risk of hypocarbia risk of hypocarbia (-->PVL) higher, and reduction of BPD or (-->PVL) higher, and reduction of BPD or airleaks seen in some, but not all, studies.airleaks seen in some, but not all, studies.

SummarySummaryThe practice of the art of mechanical ventilation The practice of the art of mechanical ventilation

lies in the application of the underlying science and lies in the application of the underlying science and physiologic concepts to the specific clinical situationphysiologic concepts to the specific clinical situation

An individualized flexible approach aimed at An individualized flexible approach aimed at maintaining adequate gas exchange with the maintaining adequate gas exchange with the minimum of ventilatory support, both in magnitude minimum of ventilatory support, both in magnitude and duration, should optimize the possible outcomeand duration, should optimize the possible outcome

Combining IMV and HFVCombining IMV and HFV

-5

-4

-3

-2

-1

0

1

2

3

4

5

0 500 1000 1500 2000 2500 3000 3500 4000

-5

0

5

10

15

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40