1 Thom Petty BS RRT Ventilation Solutions Specialist – Eastern U.S vyaire Medical – Ventilation [email protected]• Do you utilize PEEP while managing your ventilator? • How do you determine just how much PEEP is actually needed to prevent injury from cyclical de-recruitment/re-recruitment ? • Do you measure Pplat during routine Patient/Ventilator Assessments? • Does that airway Pplat truly reflect the strain experienced inside the alveoli? • How do you determine how hard your patient is working to breathe? • What effect do your efforts to determine these important factors have on your VLOS? • Especially with your fourth-quartile VLOS patients.
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Do you utilize PEEP while managing your ventilator? …...• The true pressure within the lung • PTP = PAW –PES Paw Pes Ptp • 2016 – Sahetya - Curr Opin Crit Care; 22(1):
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• Repeated cyclical de-recruitment/re-recruitment of small airways/lung units • Abrasion of the epithelial airspace lining• Worsens surfactant dysfunction• Instigates the release of inflammatory mediators into alveolar
spaces and into the systemic circulation
• QUESTION: How can the clinician determine what PEEP is truly necessary to prevent cyclical de-recruitment/re-recruitment?
• In patients requiring mechanical ventilation, prolonged high FIO2:• Worsens gas exchange• Decreases ciliary efficacy• Produces hyperoxic bronchitis and atelectasis
• Retrospective analysis of the ARMA study:• Vt, Pplat and PEEP had no correlation with mortality• Driving Pressure (DPRS) did correlate with ↑ mortality
• Even in patients receiving low-volume lung-protective ventilation
• May be a superior marker of VILI
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LUNG-PROTECTIVEVENTILATION
• 2013 – Mireles-Cabodavila - Respir Care; 58(2): 348 –366• The Three Goals of Lung Protective Ventilation:
• Provide gas exchange safely• Primum non nocere
• Provide comfort
• Promote liberation from the ventilator
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Tidal Volume Accurately measured
Respiratory RateAccurately measured
FiO2 Accurately measured
PEEPMeasured but may not accurately
reflect physiology
Plateau PressureMeasured but may not
accurately reflect physiology
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Plateau PressureMeasured but may not accurately reflect physiology
• DEFINITION:
• PPLAT is the static pressure that exerted by the volume of gas in the lungs at the end of an inhalation.
• Indicator of “lung-fullness”
• ARDSNet recommendations:• Check PPLAT:
• At least q 4h (min 0.5 sec inspiratory pause)• After each change in PEEP or VT (min 0.5 sec inspiratory pause)
• During PPV, airway pressure distends the lung and the chest wall in series.
• Chest wall edema, kyphoscoliosis, and intra-abdominal hypertension are usually associated with ↑ in pleural pressure
• Depending on the pleural pressure, the same measured Airway Pressure can be associated with considerably different PTP• Considerably different implications for injury to the lung.
• Baseline Pes = 12.5 cmH2O (+ 3.9) cmH2O• Normal patients (BMI <30)
• Baseline Pes = 6.9 cmH2O (+ 3.9)
• 2018 – Murphy – Crit Care Med; 46(6): 958-964• 285 patients in medical and surgical ICU’s
• 30% of both surgical and non-surgical pts diagnosed with intra-abdominal hypertension on admission
• Additional 15% of surgical and non-surgical pts developed intra-abdominal hypertension during admission.
• “Intra-abdominal hypertension is more common than thought”
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• To know true pressure inside of the lung (Ptp) you must account for the pressures outside of the lung (Pleural Pressures)
• Difficult to directly measure Pleural pressure but numerous studies have demonstrated reasonable correlation between Esophageal Pressures and Pleural Pressures
• 2017 – Kassis – Med Klin Intensivmed Notfmed; 113(Supp 1):513-520• Esophageal manometry simplifies the estimation of pleural
pressures• Despite the extensive use of esophageal manometry in research,
clinical adoption has been less universal.
TRANSPULMONARYPRESSURE-GUIDEDVENTILATION
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• 2008 – Talmor – NEJM; 359.20 (2008): 2095.• Problem: Optimal PEEP remains difficult to determine.
• Hypothesis: Could Esophageal Pressure measurements enable the clinician to determine a PEEP value that would maintain oxygenation while preventing lung injury due to repeated alveolar collapse and/or overdistention?
• Mechanically-ventilated ARDS patients randomly assigned to groups:• CONTROL GROUP:
• PEEP adjusted as per ARDSNet recommendations• PES-GUIDED GROUP:
• PEEP adjusted to achieve a PTP PEEP of 0 to+10 cmH2O
• 2008 – Talmor – NEJM; 359.20 (2008): 2095.• Problem: Optimal PEEP remains difficult to determine.
• Hypothesis: Could Esophageal Pressure measurements enable the clinician to determine a PEEP value that would maintain oxygenation while preventing lung injury due to repeated alveolar collapse and/or overdistention?
• Mechanically-ventilated ARDS patients randomly assigned to groups:• CONTROL GROUP:
• PEEP adjusted as per ARDSNet recommendations• PES-GUIDED GROUP:
• PEEP adjusted to achieve a PTP PEEP of 0 to+10 cmH2O
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• 2008 – Talmor – NEJM; 359.20 (2008): 2095.• Primary end point: improvement in oxygenation.• Secondary end point: respiratory-system compliance & pt outcomes.
• The study reached stopping criterion and was terminated after 61 patients had been enrolled.
• The PaO2/FiO2 ratio at 72 hours was 88 mmHg higher in the Pes-group than in the control group
• This effect was persistent through 24, 48 & 72 hr follow-up time.
• Respiratory-system compliance was also significantly improved at 24, 48, and 72 hours in the Pes-guided group
• 2008 – Talmor – NEJM; 359.20 (2008): 2095.
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WHAT’S IN THE JOURNALS
• Increases in Peak Airway Pressure without a concomitant increase in alveolar distension (↑ Ptp) are unlikely to cause damage• Critical variable is not PIP but Ptp
• In pts with a stiff chest wall from non-pulmonary ARDS that may have elevated pleural pressures, airway Plateau Pressures may exceed 35cmH2O without causing alveolar distension
! Esophageal pressure can be used to estimate transpulmonary pressures
A SAMPLING OF WHAT’S IN THE JOURNALS
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! Systematic use of Pes has the potential to improve ventilator management in ARF by providing more direct assessment of lung-distending pressure
A SAMPLING OF WHAT’S IN THE JOURNALS
! Using Airway Plateau Pressures to set ventilation may under-ventilate patients with intra-abdominal hypertension and over-distend the lungs of patients with atelectasis.
! Ptp must be used to accurately set mechanical ventilation in the critically ill.
A SAMPLING OF WHAT’S IN THE JOURNALS
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! Utilizing Pes for PEEP titration results in ↑ elastance and ↓ driving pressures compared to conventional PEEP titration.
A SAMPLING OF WHAT’S IN THE JOURNALS
! Pplat > 25 cmH2O! Cstat < 40 ml/cmH2O! P/F Ratio < 300! PEEP > 10 cmH2O to maintain SaO2 > 90%! PaCO2 > 60 mmHg or pH < 7.2 attributable to respiratory acidosis
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! 5fr or 7fr balloon-tipped catheter or a specialized 16fr NG/OG catheter with balloon tip
! Inserted into the lower third of the esophagus, above the diaphragm.
! An approximation of proper placement can be made by measuring the distance from the tip of the nose to the bottom of the earlobe and then from the earlobe to the distal tip of the xiphoid process of the sternum.
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• Baydur Maneuver:• During a patient-initiated breath during an expiratory hold a
properly positioned inflated balloon will show simultaneous negative Paw & Pes deflections
• If balloon is inserted too far into the esophagus Pes will deflect positively during a spontaneous inspiration.
• PES should be similar (+ 10) to PGA (Bladder Pressure)• Measurements should match the patients clinical presentation.
• Cardiac Oscillations:• A properly inserted inflated balloon may show small cardiac
oscillations reflective of cardiac activity.• May need to re-scale Y-axis of waveform to visualize
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! ↑ pleural pressure skews the airway Pplat upwards