Prof. Javier García Fernández MD, Ph.D, MBA.Chairman of Anesthesia & Perioperative Medicine Department

Puerta de Hierro Universitary HospitalProf. of Anaesthesia and Perioperative Medicine. AutonomaMedical School. UAM

Madrid‐Spain

Physiopathology of VILI: Normal breathing Lungs are designed to receive an homogenous distributed low tidal volume of 6 ml/kg of PBW

If you have an increase in the  oxygen demand, the physiologic response is increase respiratory rate and change I:E relation to 1:1 by an active expiration

Just what neonates do always !!!!

NO ATELECTASIS, NO CICLIC COLAPS, NO CICLIC OVERDISTATION

Espontaneus breathing heathylungs: the way we breath

InspirationEspiration

Physiopathology of VILI: How Mechanical ventilation damage the lungs

Atelectrauma vs ciclic tidal recruitment:

Barotrauma vs Stress vs Strain vs Driving pressure

No ventilated lung areas (atelectasis) vs ciclicoverdistended lung areas

Biotrauma:  

What is “high PEEP” and what is “low PEEP” for you?

Is there a “magic PEEP” good for all patients ?

Is there a “magic PEEP” good for the same surgical procedure or all ARDS?

Does everyone need the some PEEP for the some PO2?

What is PEEP for and how to program it ?• PUBMED 02/2017: 25246 PAPERS ABOUT PEEP• WHAT IS PEEP FOR ? Does PEEP of 5 -10 cmH2O

recruit the lungs ?• HOW TO PROGRAM PEEP ?• What is “high PEEP” and what is “low PEEP” for you?• Is there a “magic PEEP” good for all patients ?• Does PEEP increase or reduce the risk of pneumothorax

?• Does everyone need the some PEEP for the some

PO2/Sat O2?

What does PEEP do ? and what doesn't ?

What is “baby lungs” concept in ARDS?

¿Does PEEP recruit the lungs ?

• PEEP 5 cmH2O

• PEEP 10 cmH2O

• PEEP 15 cmH2O

• PEEP 20 cmH2O

Effects of PEEP/CPAP

•Com

plia

nce

(mL/

cmH

2O)

•PEEP (cmH2O)

•10

•20

•30

•40

•50

•60

•0 •10 •20 •30 •40

•Lung recruitment

Incremental vs Decremental PEEP

•V•P

•C =

About PEEP we can say:About PEEP we can say: “PEEP has to be programmed individually, for this patient, in this right moment,

“PEEP only works to keep the lung opened, it never open the lung” so…

“PEEP has to be programmed always after an previously opened lung” so..

Recruit maneuvers  should be preformed before set PEEP with some exceptions: COPD and any other situation of bronquial obstruction

Anesthesia most of cases around 5 and less then 10 except, obese patients and laparoscopic surgery that you have to individualize

Best lung mechanics: the best elastic point = highest Cdyn + less Plateau preasure + less driving pressure

Less Shunt: best PaO2/FiO2 or  best Sat/FiO2

Less dead space: the less PCO2‐EtCo2  point

Volumetric capnography: the best point to diffusion

“See it “ =  Lung Echography or Electric Impedance tomography (EIT)

Lower pulmonary resistance: best right ventricular function 

g gHow can we guide the PEEP setting ?

If I were a ventilator and someone programme me with6  ml/Kg and I have to ventilated all of your lungs at 

the same time, all of you respond with the sameamount of pressure ? 

What physiology can tell us about VtWhat physiology can tell us about Vt

Neonates only use 6 ml/kg of Vt

Neonates cannot suspire

Neonates cannot increase the Vt per kilo 

Neonates increases the minute volume they need by increasing respiratory rate never the Vt

•N = 466

ARDS net. N Engl J Med 2000;342:1301-8

•6 ml/kg

•12 ml/kg

Adapt the volume tidal to the real anatomical size of the lung

First great improvement:   Vt de 6 ml/Kg of PBW

PEEP

Driving Pressure (ΔP)

Plateau press.VT

Ventilatory induced lung injury (VALI orVILI)

CRS

= Plateau (volume) or maximum (pressure) pressure - PEEP

“Driving pressure” = is Vt according the functional size of the lungs = Vt/ Cdyn

Courtesy of Dr. J.B. Borges. Mechanical ventilation course. Madrid. 2011

The new Dr. M. AMATO´s approach to VILI

Tidal volume vs driving pressure

What we can say is

“The reduction in tidal volume is important in order to obtain a reduction in driving pressure but it is not important by itself, and there is not a magic number, because it depend on the elasticity of the lung in that moment(Compliance)”

Tidal volume vs driving pressure

DP < 10:  (physiological, no worries)

DP 10‐14: (the limit to produce VILI “the less the better”)

DP > 15 you are producing VILI do something else !!!

Positive End-Expiratory Pressure after a Recruitment Maneuver Prevents Both Alveolar Collapse and Recruitment/DerecruitmentJeffrey M. Halter, Jay M. Steinberg, Henry J. Schiller, Monica DaSilva, Louis A. Gatto, Steve Landas, and Gary F. NiemanAm J Respir Crit Care Med 2003;167: 1620–1626,

DRIVING PRESSURE 

PEEP of 5 cm H20 PEEP of 10 cm H20

In both situations the plateau pressure is = 30 cmH2O

Driving pressure of 25 cmH2O Driving pressure of 20 cmH2O

ConclusionsDriving pressure is the most important independent ventilation variable to avoid VILI

Never use more than  > 15 cmH2O

Driving pressure in ARDS “the less the better” between 10 and 14 cmH2O

Is the same the way you preform the RM (VCV vs PCV) ?

Is the same to set a fix PEEP to everybody or individualise it ?

Should be the same to apply the some pressure to all patients ?

Is the same to set even the same PEEP before or after a RM?

1. Atelectasis may develop in nearly 90% of patients under general anaesthesia, and persist (36 %) in PACU and in some patients up to the patient start walk (2-3 days)

2. Persistence of atelectasis after surgery has been associated with PPC: pneumonia, acute lung injury, extubation failure requiring re-intubation and hypoxemia

3. Hypoxemia, a direct consequence of atelectasis, may also promote systemic complications such as acute myocardial o neurological ischemia, cardiac arrest or impaired wound healing, etc.

So far, our unique objective is to avoid hypoxemia by increase FiO2 but nobody pay attention to solve the

mass of lung collapsed in the OR or in the PACU

IMPROVE trial. N Engl J.2013; 369: 428‐37

Conclusions Alveolar recruitment maneuvers followed by PEEP should be instituted after induction of general anesthesia, routinely during maintenance, and in the presence of a falling SpO2 whenever feasible. 

RM allow the anesthesia provider to reduce the FIO2 while maintaining a higher SpO2, limiting the masking of shunts. 

Utilization of alveolar recruitment maneuvers may reduce postoperative pulmonary complications and improve patient outcomes.

Conventional mechanical ventilation:

Recruit maneuvers (RM)

1. CPAP or sustained insufflation:40 cmH2O / 40 secondsNEVER in children (bradycardia).

2. Few cycles at high pressure:4-6 cycles 50 cmH2O.NEVER in children (barotrauma risk).

3. PCV with constant driving pressure y PEEP:Fixed driving pressure of 15 cmH2OPositive end-expiratory pressure (PEEP) was incrementally increased by

steps of 5 cmH2O from ZEEP to a PEEP of 20-30 cmH2O.Decrement PEEP titration in steps of 2 cmH2O until you reach the

maximum C dyn (collapse point).Second open up maneuver and set a final PEEP 2 cmH2O above the

collapse point.

Recruit maneuvers (RM)

Recruit maneuvers (RM)

Recruit maneuvers (RM)

Recruit maneuvers (RM):PCV with driving pressure of 15 cmH2O

15

40 (45-60)35

3025

20

PCVDriving Pressure15 cmH2O

VCV for a driving pressure <15 cmH2O

Collapse point:Reduce of Cdyn

+ Lung protectiveventilation

510

1520 20

How to program a RM ?

RR: 20 bpm

I:E: no need to change 1:2

PIM: adults 40 children 30 cmH2O

Max PEEP: adults 20 children 15 cmH2O

FiO2: no need to change

PEEP at the end: most cases less than 10; obesepatients and laparoscopic procedures indivudualicesometimes even more than 15 cmH2O.

Automatic Recruitment Manouvers 

Protective ventilationProtective ventilation1. PEEP must be program individually and after obtained an open

lung (after Recruitment maneuvers), in anesthesia, less than 10 in

most of cases, (around 5 for conventional surgery).

2. Protocol of no disconnection no suction

3. Please stop bagging the patients to recruited

4. Reduction of Vt of 6 ml/kg and watch over DRIVING PRESSURE

!!! and the role is less than 13 cmH2O

5. Trust the information of the curves and loops: No fix and

constant I:E relation and better high respiratory rate than high

driving pressure (Physiological programming)

5. Individualize the oxygenation and hypercapnia level in each

patient each day (Permissive or adaptive hypercapnia for pH > 7,2)

6. FiO2 < 0.7

7. Fluid balance: restricted

8. Prono sometime helps improving V/Q before ECMO in ARDS

9. Induced hypothermia: (34-35º C) and paralysis in extreme difficult

ventilate situations

10. Mechanical assistant devices: CO2 removal systems or respiratory

ECMO as final rescue therapy

Protective ventilationProtective ventilation

TIMING IS CRUTIAL (THERAPEUTIC WINDOW)(MOST OF THIS ACTIONS WORK WELL IF YOU APPLY THEM WITHIN THE FIRST 2 DAYS OF THE ONSET OF ARDS)

English version:This advanced mechanical ventilation course is designed for

experienced hospital staff with at least four years’ experience in ventilation techniques and is especially appropriate for professionals such as Chiefs of Department, Unit Coordinators or Resident Tutors, who are responsible for training other professionals. There are only

25 participants per course

Thanks¿ Questions?ventilacionanestesia@gmail.com