Ventilator Induced Lung Injury Ventilator Induced Lung Injury Ventilator Strategies Ventilator Strategies Pathophysiology Matters Pathophysiology Matters Donald M. Null, Jr., MD Donald M. Null, Jr., MD Donald M. Null, Jr., MD • I am a consultant for Draeger Medical Company I am a consultant for Draeger Medical Company
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– Larger than an adult– More distensible– PIE worsens compliance
Barotrauma Barotrauma (continued)(continued)
• Distal airway overdistention
– Protein leak– Edema– Hyaline membrane formation
Ventilator Associated Lung Injury
• PIP
• Volume
Hernandez et. al.
Dreyfus et. al.
Carlton et. al.
Oxygen Injury
• Oxygen is toxic to all tissues
• Lack of antioxidant protection
• O2 injury perpetuates alveolar noncompliance
BiotraumaBiotrauma
EpigeneticsEpigenetics
Goals of Respiratory SupportGoals of Respiratory Support
•• Achieve uniform inflationAchieve uniform inflation•• Minimize over and under inflationMinimize over and under inflation•• Minimize inspired oxygen concentrationMinimize inspired oxygen concentration•• Early appropriate extubation Early appropriate extubation
Lung RecruitmentLung Recruitment•• Increase Mean Airway PressureIncrease Mean Airway Pressure
– Stabilization of lung volume– Improved ventilation - perfusion– Stabilization of cerebral blood flow– Decreased air leaks– Weaning
MMVMMV
High Frequency Types High Frequency Types and Differencesand Differences
–– High frequency positive pressure ventilationHigh frequency positive pressure ventilation–– High frequency flow interruption ventilationHigh frequency flow interruption ventilation–– High frequency jet ventilationHigh frequency jet ventilation–– High frequency oscillatory ventilationHigh frequency oscillatory ventilation
Pressure TransmissionPressure Transmission
Ventilation Ventilation --Conventional vs High FrequencyConventional vs High Frequency
CV CV -- V = (TVV = (TV--DV) x FDV) x FV = AV x FV = AV x F
Mechanisms to Mechanisms to Achieve RecruitmentAchieve Recruitment
1. Surfactanta. Delivery technique
2. Adequate mean and end expiratory pressure to prevent collapse
Mechanisms to Mechanisms to Achieve RecruitmentAchieve Recruitment
3. Recruitment maneuversa. Sighb. Inspiratory time
4. Adequate target volume
MistakesMistakes
1. Inappropriate pressure changes PIP, PAW, PEEP
2. Use of high FiO2 to treat intrapulmonary shunts
MistakesMistakes
3. Distensability of airways with effecton tidal volumes
4. Inappropriate ventilator rates that predispose to airtrapping
MistakesMistakes
5. Mucus plugging not appropriatelyaddressed
Meconium AspirationMeconium Aspiration
1. Diffuse Disease
2. Patchy – Overdistention/Atelectasis
StrategiesStrategies
- Similar to DAD but rememberingdue to meconium there is a prediliction for air-trapping
- Goal is to minimize overdistentionand air-trapping. Recruitment of atelectatic areas as possible.
Basic StrategyBasic Strategy
•• Lower rates for HF or conventional Lower rates for HF or conventional yielding longer expiratory timesyielding longer expiratory times
•• Larger tidal volumes for HF or Larger tidal volumes for HF or conventionalconventional
•• Surfactant usageSurfactant usage
MistakesMistakes
- Too small tidal volumes- Too rapid rates- Preconceived appropriate tidal
volume
MistakesMistakes
Failure to deal with cardiac issuesPPHN
Pulmonary HypoplasiaPulmonary Hypoplasia
Bilateral/DiffuseBilateral/Diffuse
- Maintain adequate inflation
- Avoid overexpansion
- Surfactant treatment
- Pulmonary hypertension
UnilateralUnilateral
Management Directed Management Directed Primarily at Normal LungPrimarily at Normal Lung
- Avoid overexpansion
- Prevent atelectasis
- Surfactant treatment
- Pulmonary hypertension
MistakesMistakes
1. Using too large tidal volume
2. Failure to address cardiac/pulmonary hypertension issues
3. Adequate expansion misinterpreted on x-ray
MistakesMistakes
1. Rib counting
2. Tidal volume
SevereSevereAir LeakAir Leak
StrategiesStrategies
Premature PIE
- Short inspiratory time
- PEEP – Adequate to keepairways open
- Rate 40-50
- Tidal volume – 3-4 cc/kg
HFVHFV
•• Paw 1 cm HPaw 1 cm H220 < CV0 < CV•• Frequency 10Frequency 10--15 Hz15 Hz•• Delta pressure Delta pressure –– minimal chest minimal chest
wall movementwall movement
Gross Air LeakGross Air LeakAdequate InflationAdequate Inflation
- Short inspiratory time
- PEEP – 3-4
- Rate – 40-50
- Tidal volume – 3-4 cc/kg
HFVHFV
–– Gross Air LeakGross Air Leak•• Paw = or 1 cm HPaw = or 1 cm H220 > CV0 > CV•• Frequency 10Frequency 10--15 Hz15 Hz•• Delta pressure Delta pressure –– chest wall movementchest wall movement
Gross Air LeakGross Air LeakGenerally Poor InflationGenerally Poor Inflation
- Inspiratory time – .35-.4
- PEEP – 5-7
- Rate – 40
- Tidal volume – 5-6 cc/kg
HFVHFV
–– Gross air leak, generally poor inflationGross air leak, generally poor inflation•• Paw 1Paw 1--2 cm H2 cm H220 > CV0 > CV•• Frequency 10 HzFrequency 10 Hz•• Delta pressureDelta pressure--chest wall movementchest wall movement
SummarySummary
The enemy of good is better
- Applying ventilatory support in the least traumatic way is best accomplished by applying the support over the mid-portion of the pressure volume curve.
Issues with VentilationIssues with Ventilation
• A 5 cc/kg tidal volume does not insure prevention of over-expansion or injury
• A 10 cc/kg tidal volume does not insure over- expansion and injury
Issues with Ventilation Issues with Ventilation (continued)(continued)
• Weaning which results in keeping the lung on the lower portion of the PV curve will injure the lung not protect it
- The lung is most vulnerable to injury during recruitment
One must tailor ventilator One must tailor ventilator strategies to match strategies to match cardiopulmonary pathophysiologycardiopulmonary pathophysiology
Remember:Remember:Cookbooks are good butCookbooks are good butpatients are individualspatients are individuals