ventilacion neonatal

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Neonatal Neonatal

VentilationVentilation

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1960 and 70’s1960 and 70’s

Treatment of neonatal respiratory failure

• CPAP and time-cycled, pressure-limited IMV.

• Causes of neonatal pulmonary disease not well understood

• Equipment was basic

• Monitoring limited to clinical assessment intermittent radiography

blood gas assessment.

Treatment was not disease-specific strategies

Historical Aspect of Neonatal VentilationHistorical Aspect of Neonatal Ventilation

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1971 – Gregory at al – improved survival in RDS with CPAP

1972 - deLemos - continuous flow ventilation for newborns

1973 - Downs at el – introduction of IMV

Historical Aspect of Neonatal VentilationHistorical Aspect of Neonatal Ventilation

Reynolds – 1971; 1973

↑ PEEP, ↑Ti → improved PaO2

Related to PAW

Boros et al – 1977; 1979

↑ Paw → ↑ oxygenation and removal of CO2

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Vent Settings:

PIP high 25 – 40 cms H20

PEEP low < 6 cms H20

Rate Low < 40

Ti prolonged gen. 0.5 -1.5 secs

I:E most often reversed

High FiO2 = BPD

↑ MAP = Oxygenation

Target : Rapid decrease FiO2

Assumptions:Assumptions:

Approaches to MV:Approaches to MV:

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Development of continuous monitoring devices, eg TCO2

→→ greater understanding of dynamic nature of neonatal lung disease

late 1970slate 1970s

Echocardiography

→→ showed the unique interdependence of heart and lungs and the role

of the ductus arteriosus in several disease states.

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• Development of specifically designed ventilators for neonatal use.

• Newer modes of ventilation

ResultResult

1980s1980s

• Proliferation of new ventilatory techniques

• Widespread clinical trials

• Surfactant replacement

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Studies in the 1980s

Entrainment of the infant’s respiratory efforts by:

• ↑ ventilator rate to 60 breaths/min or above

• shortening the inspiratory time

→ inspiration and inflation coincided.

termed SynchronisationSynchronisation associated with improvement in blood gas tensions

→ ↓ Active expiration ( breathing against the ventilator )

may explain the lower incidence of pneumothoraces

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Physiological studies comparing synchronised intermittent positive pressure ventilation (SIPPV) or synchronous intermittent mandatory ventilation (SIMV) to IPPV/IMV

→ increased synchrony,

→ ↑ tidal volume

→ improved blood gas exchange,

→ ↓ work of breathing

→ ↓ blood pressure and cerebral blood flow velocity

fluctuations

Studies in the 1980s

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• Pulse oximetry was a standard of care,

• Surfactant replacement therapy was well underway

• Synchronised Ventilatory modes preferred

• HFV / HFO had become established as an alternative technique

• ECMO accepted as the ultimate rescue therapy

• Realisation of role of excessive tidal volumes in lung injury

By the end of the 1980’s

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Studies on mechanisms of lung injury recognised:

• Barotrauma

• Volutrauma

• Atelectrauma

• Oxidant stress

• Inflammatory mediators

• Infectious agents (“biotrauma”)

By the end of the 1980’s

Led to development of chronic lung disease (CLD)

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1980+ 90’s1980+ 90’s

High Airway Pressures = Lung Injury ( Barotrauma )

Large tidal volumes = Lung Injury ( Volutrauma )

Optimal lung volume = decrease lung injury

Insufficient PEEP = Atelectrauma

Supraphysiologic rates = minimal pressure exposure

Synchronisation = decreased iatrogenic damage

Assumptions

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MV – the new approachMV – the new approach

Goal:

Prevent Barotrauma, volutrauma, atelectrauma, biotrauma

Lung Recruitment

Promote spontaneous breathing

Decrease WOB

SynchronisationVent. Settings:

• Lower PIP’s

• Monitor Vt’s or set VT

• No PEEPophobia

• Shorter Ti

• No reverse I:E ratio’s

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Lung InjuryLung Injury

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Treatment of Respiratory Failure Treatment of Respiratory Failure at the Turn of the 21st Centuryat the Turn of the 21st Century

HFJV

PSVPSV HFOVHFOV

ECMO

Liquid ventilation

Liquid ventilation

SIMV

A/C

Nitric OxideOxideNitric OxideOxide

Volume ventilation

Lung Protective Strategy

CPAP

?

?

??

????

?

VGVGVGVG PSVPSVPSVPSV

IMV

TCPL

NIPPVNIPPV

SIPPVSIPPV

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Goals of Respiratory ManagementGoals of Respiratory Management

Maintain acceptableacceptable gas exchange with a minimum of:

– lung injury

– hemodynamic impairment

– other adverse events (i.e. neurologic injury)

– Minimize work of breathing

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Lung InjuryLung Injury

• Excessive TVs damage lungs:

– epithelial injury

– increased microvascular permeability/pulmonary edema

– protein leak & surfactant inhibition

– airleak syndrome

• High FiO2 has a similar effect

• Volutrauma not Barotrauma is the culprit

• Low lung volume is just as bad as excessive lung volume

• Permissive hypercapnia allows us to use lower TV

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Exp

VentilatedStable

VentilatedUnstable

Unventilated

“Baby Lung” “Atelectotrauma”Recruitment/de-recruitment injury

Non-Homogenous Aeration in RDSNon-Homogenous Aeration in RDS

Insp

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Lung Protective Strategy Lung Protective Strategy

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Matching Ventilation Strategy to Matching Ventilation Strategy to Disease PathophysiologyDisease Pathophysiology

• One-size-fits-all ventilation is out

• Consider the underlying disease process

• Determine the primary pathophysiology

– Atelectasis

– Pulmonary hypertension

– External chest wall restriction

– Air-trapping

– Circulatory failure

Determine appropriate strategy

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High FRC due to over-expansion or air-trapping(OBSTRUCTIVE LUNG DISEASE)

Normal FRC with optimal lung expansion

Low FRC due to lung hypoplasia, under-expansion, or atelectasis (RESTRICTIVE or ATELECTATIC LUNG DISEASE)

A

B

C

PHYSIOLOGIC BASIS FOR CATEGORIZING LUNG DISEASEPHYSIOLOGIC BASIS FOR CATEGORIZING LUNG DISEASE

VO L UM E

P R E S S U R E

TLC

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Ventilator StrategyVentilator Strategy

Oxygenation:Oxygenation:

• Efficiency depends on optimizing V/Q matching.

• V/Q matching is a function of maintaining optimal lung volume.

• Lung volume is proportional to Paw.

• Oxygenation is possible without ventilation.

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CO2 exchange:CO2 exchange:

• Depends on flux of gas in/out of alveoli.

• Affected greatly by the mechanical properties of the lungs:

• resistance

• compliance

• time constants


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Minimize work of breathingMinimize work of breathing

Lung Volume

Patient’sPleural Pressure

MachineGeneratedPressure

Lung Volume

Work of Breathing

CPAP/SIMV (unsupported) A/C or PSV



Lung Volume

SIMV (supported)




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Looking at Tidal VolumeLooking at Tidal Volume

• Tidal volume less than or close to total dead space

→ insufficient exchange of alveolar gases

• Too large a tidal volume

→ alveolar and airway over distension and shear stress damage

• Lung overstretching and over distension

more significant in causing lung injury rather than high pressures alone

Preventing lung injuryPreventing lung injury


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Volume associated lung injuryVolume associated lung injury

* Role of tidal volume, FRC and end-expiratory volume in the development of pulmonary oedema following mechanical ventilation.Dreyfuss D; Saumon G Am Rev Resp Dis 1993; 1485 (5): 1194-1203

* Chest Wall restriction limits high airway pressure induced injury in young rabbits

Hernandez LA; Peevy KJ; Muise AA at el J Appl Physiol 1989; 66:2364

* Barotrauma is volutrauma, but which volume is the one responsible? Dreyfuss D, Saumon G. Intensive Care Med 1992;18:139-41.

* Manual ventilation with a few large breaths at birth compromises the therapeutic effect of subsequent surfactant replacement in immature lambs.Bjorklund LJ, Ingimarsson J, Curstedt T, et al. Pediatr Res 1997;42:348-55.

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Lung injury - Lung injury - Early StudiesEarly Studies

Chest wall restriction limits high airway pressure-induced lung injury in young rabbitsLUCRECIA A. HERNANDEZ, KEITH J. PEEVY, ALICIA A. MOISE, AND JAMES C. PARKER

1989 the American Physiological Society

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Dreyfuss et al-1988

Lung injury - Lung injury - Early StudiesEarly Studies

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Using a strategy that

• promotes lung recruitment

• but limit tidal volume

can reduce lung injury and promote better outcomes.



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• Tidal volume targeting

• Monitor tidal volumes

• Use of the right amount of PEEP

• Understanding lung mechanics role in optimizing ventilation

• Low pressure does not equal low risk

• High pressure does not equal high risk



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1. Choice of various modes

2. Monitoring of lung mechanics

3. Real time Graphics

4. Leak Adapted Ventilation

2121stst Century expectations Century expectations

Features of a Neonatal Ventilator

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Babylog 8000 Plus Babylog 8000 Plus

meets your needs and more…….meets your needs and more…….

• Pressure, Volume, Flow and O2 -Monitoring integrated

( Flow monitoring at Wye piece for accuracy )

• Lung Mechanics Values

Ventilation ModesVentilation Modes

• IMV / IPPV

CPAP

SIMV

SIPPV

PSV (Option)

VG (Option)

HFV (Option)

NCPAP ( option )

ventilacion neonatal

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