21/09/2018

Invasive Ventilation Is lung protection necessary in the ED?

Helen Askitopoulou MD, PhD, FRCA, DA Professor Emeritus, University of Crete

No Conflict of Interest

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Invasive Positive Pressure Ventilation Is lung protection necessary in the ED?

• Invasive ventilation in the ED: the facts?

• Lung Injury: Why? How soon?

• Is it necessary to protect the lungs from IPPV in the ED?

Invasive Positive Pressure Ventilation in the ED What are the facts?

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2012;30;1183‐8

• approximately 240.000 patients per year are ventilated in US EDs, representing approximately 0.23% of all ED visits or 0.85 visits per year per 1000 US population • ¾ of ventilated patients stayed in the ED almost 2 hrs, • ¼ were present for more than 5 hrs • 24% in‐hospital mortality of mechanically ventilated pts

pts mechanically ventilated in the ED

• Many mechanically ventilated pts in the ED have protracted lengths of stay while awaiting ICU admission – Scand J Trauma Resusc Emerg Med 2012;20:30 – Crit Care Med 2007;35(6):1477‐83 • more than 20% of ED pts receiving ventilation develop pulmonary complications, such as ARDS and ventilator-associated conditions, which adversely affect outcome – Shock 2013;40:375‐381 – J Crit Care 2015;30:1163‐1168

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Emergency Department concerns about the quality of in the ED

the portal of entry of the highest risk patients for ARDS

• Lung protective ventilation was uncommon in the ED • Given – the frequency of ALI & ARDS in the ED, – the progression to ARDS shortly after ICU admission, – that ventilator‐induced lung injury (VILI) can develop within hours, and progression to ALI occurs early in the course of respiratory failure • The effect of ED‐based interventions to reduce the sequelae of ALI should be investigated further

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Key messages • higher tidal volumes are causal in the development of ARDS. • ARDS occurs early in the course of mechanical ventilation, • suggesting that ARDS‐PREVENTION trials should occur EARLY in the course of mechanical ventilation, • such as in the EMERGENCY DEPARTMENT.

Protecting the lungs in the ED

Ventilation Induced Lung Injury (VILI) Understanding the mechanisms of lung damage

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VentilaTOR‐Induced Lung Injury VILI ventilatory setting VentilaTION‐Induced Lung Injury forces acting on lung parenchyma how mechanical ventilation injures the lungs

wide series of lung damages VILI from edema to gross pneumothorax

Gattinoni et al. Crit Care Clin 34 (2018) 343–35

One GATTINONI ΗΙΤ MODEL

Volu‐ Strain trauma stress risers stress Atelec‐ VILI trauma Baro‐ trauma

Bio‐trauma

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physical forces may cause release of various intracellular mediators either directly or indirectly ⇒ Biotrauma Slutsky AS, Ranieri M. Ventilator induced lung injury. NEJM 2013;369:2126

“Biotrauma Hypothesis” One Hit OR Multiple HITS? • Strong form: – mechanical ventilaTION induced inflammation may suffice to injure the lungs much stronger than explained by the mechanical forces alone (one hit model) • Weak form: – ventilaTOR‐induced inflammation contributes to the mortality of ARDS patients in conjunction with other factors (multiple hits model)

Anesthesiology 2017; 126:909‐22

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Multiple ΗΙΤ MODEL

direct lung indirect insult lung insult ARDS potentially Sepsis Pneumonia Trauma Aspiration iatrogenic Pancreatitis Toxic inhalation disease Post arrest syndrome Lung injury Transfusions multiple Lung vasculitis Serious burns

Harmful mechanical ventilation leading to VILI in healthy lungs

Intensive Care Med 2013;39:6–15

protective strategies to reduce lung damage during mechanical ventilation

↓ VT /EELV

↓ strain ↓ Ptp or respiratory ↓ rate ↓ Pplateau mechanic ↓ stress VILI↓ al power

↓ Ppeak stress PEEP ↓risers recruitment

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volutrauma

↓strain lung protective ventilation: 1st Strategy

focuses on Low‐tidal Volume Ventilation (< 6 ml/kg/PBW) to reduce lung strain from Volutrauma and over-distension of alveoli from large tidal volumes

VT = 6 ml/kg/PBW safe for all patients??

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the “baby lung” of ARDS areas with very low compliance make the functional lung inflated smaller than expected from small somatometric airway features collapse

alveolar VT is directed to collapse alveoli with normal compliance causing Gattinoni L, et al. The ‘‘baby lung’’ became an OVERDISTENTION adult. Intensive Care Med 2016;42:663–673

Barotrauma ↓ stress

lung protective ventilation: 2nd Strategy

focuses on reducing lung stress & by adjusting tidal volumes according to static compliance to lower

driving pressure (VT/CRS) Ventilation even at low lung volumes can also cause injury

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Driving Pressure (ΔP) =

Ptp(insp) –Ptp(exp) = Pplateau – PEEP

Pplateau

mean Paw Palv Intrinsic PEEP Ppl External PEEP

Palv at zero flow = Pplateau Ppl is measured as Poesophageal

… driving pressure as opposed to tidal volume and PEEP could further enhance lung protection by adjusting tidal volumes according to the size of the lung available for ventilation (reflected by the static compliance)

ΔP = Pplateau – PEEP  15‐20 cmH2O

CRS = VT / [Pplateau – PEEP] ΔP = VT / CRS

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higher Pplateau: not always protective higher PEEP: not always protective

ΔP = driving pressure, S1‐S5 = five distinct subsamples of patients

• lower survival rate among patients with higher ∆P and • higher survival among patients with lower ∆P • independent of concomitant variations in PEEP and

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Atelectrauma Stress ↓ risers

lung protective ventilation: 3rd Strategy

focuses on adjusting PEEP to stabilize the lung & minimize repeated opening and closing of alveolar units and open up the lung

Atelectrauma / dynamic strain

Ventilation that occurs at low lung volumes can also cause injury through multiple mechanisms, including repetitive opening and closing of airways and lung units, causing ⇒

Slutsky AS, Ranieri M. Ventilator induced lung injury. NEJM 2013;369:2126

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• “‘The best PEEP’ does not exist” – we may find a PEEP level that avoids intra‐ tidal recruitment–derecruitment, …, – without causing hyperinflation and affecting hemodynamics, – reflects a wishful dream that has nothing to do with the reality

• we should use a ‘better PEEP’ approach • as a reasonable compromise among • oxygenation, hemodynamics status, intra‐tidal opening and closing

– Higher PEEP in severe ARDS (range 15–20 cmH2O) – Lower PEEP in mild ARDS (range 5–10 cmH2O) – Intermediated in moderate ARDS

paying attention to the Ecw and hemodynamic impairment

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mechan ical energy x power time

lung protective ventilation: 4th Strategy focuses on respiratory rate energy and time define the mechanical power

Crit Care Clin 2018;34:343–356

Mechanical power: a new way of looking at VILI • VILI is caused by the delivery of a critical amount of mechanical energy to the lung applied over time • energy and time are the 2 essential components of VILI • considered together, they define the mechanical power • every component of the mechanical ventilation:

– VT, driving pressure, respiratory rate, flow, & PEEP • contribute, each one at a different extent, to the mechanical power delivered to the respiratory system (and to the lung) Critical Care Medicine 2017;45(3):e327–e328 Crit Care Clin 2018;34:343–356

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Lung‐Protective Ventilation to reduce the risk of VILI A Neglected Area in the ED that it is necessary to change

EDITORIALS AJRCCM 2015;191(2):125‐126

HOW SOON?  Clinicians should move to initiate low tidal volume ventilation as soon as possible in ARDS  ... timely recognition of ARDS and timely adherence to low tidal volume ventilation is important for reducing mortality

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Which patients?

healthy ARDS lungs

lung homogeneity

lung in‐ homogeneity

Healthy Lungs Injured Lungs

initial settings initial settings V = 6‐8 ml/Kg IBW T VT = 4‐6 ml/Kg IBW PEEP = 6‐8 cmH O 2 PEEP = 8‐15 cmH2O recruitment /30‐45 min recruitment selected pts

goal ‐ monitoring goal ‐ monitoring

Pplateau < 25 cmH2O Pplateau < 30 cmH2O ETCO2 > 35‐45 mmHg ETCO2 > 40‐55 mmHg SpO2  95 % pH = 7.30‐7.40 SpO2  92 % Anesthesiology 2014;121:400‐8

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Protecting the lungs in the ED

In Summary

Key challenges of IPPV in the ED: personalisation of mechanical ventilation

• minimise STRAIN (volutrauma)

– reduce VT (on driving pressure) = 6 mL/kg PBW • minimise STRESS (barotrauma)

– reduce Pplateau (on driving pressure) • ARDS < 30 cm H2O • healthy lungs < 15‐20 cm H2O • maintain driving pressure ≤ 15‐20 cmH2O • minimise LUNG INHOMOGENEITY (atelectrauma) – personalise PEEP (on driving pressure ‐ dynamic compliance ‐ stress index) start  5 cmH2O – personalise recruitment manoeuvre • adjust RESPIRATORY FREQUENCY  18–22 breaths/min – personalise according to mechanical energy of ventilator

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Invasive Ventilation Is lung protection necessary in the ED? a lot of Data but still more questions than answers Thank you

Transpulmonary Pressure (Ptp) ‐ Driving Pressure (ΔP) • Transpulmonary Pressure

Ptp = Paw –Ppl separates the pressure delivered to the lung from the one acting on chest wall PEEP and abdomen

– Paw = Palv at zero flow = Pplateau – Ppl is measured as Poesophageal • Driving Pressure (ΔP)

ΔP = Ptp(insp) –Ptp(exp) = Pplateau – PEEP reflects the distending pressure taken by the lungs when VT is delivered stands for the VT‐induced lung stress

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Impact of PEEP on lung  hemodynamics – ICP  ICP ‐  CPP

ΡΕΕΡ Preexisting cardiovascular conditions

 VR ‐  CO PVR ‐ RV afterload  LV afterload ‐  CO (M. Vardas, et al. PEEP Role in ICU and Operating Room Scientific World J 2014)

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