Prof. Javier García Fernández MD, Ph.D, MBA. Chairman of Anesthesia & Perioperative Medicine Department Puerta de Hierro Universitary Hospital Prof. of Anaesthesia and Perioperative Medicine. Autonoma Medical 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 heathy lungs: the way we breath Inspiration Espiration
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 ciclic overdistended 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
Incremental vs Decremental PEEP 60 Compliance (ml/cmh 2 O) 50 40 30 Lung recruitment V C = P 20 10 0 10 20 30 40 PEEP (cmh 2 O)
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
How can we guide the PEEP setting? 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
If I were a ventilator and someone programme me with 6 ml/kg and I have to ventilated all of your lungs at the same time, all of you respond with the same amount of pressure?
What 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
ARDS net. N Engl J Med 2000;342:1301-8 N = 466 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
The new Dr. M. AMATO s approach to VILI V T Plateau press. PEEP C RS Driving Pressure (ΔP) Driving pressure = is Vt according the functional size of the lungs = Vt/ Cdyn = Plateau (volume) or maximum (pressure) pressure - PEEP Ventilatory induced lung injury (VALI orvili) Courtesy of Dr. J.B. Borges. Mechanical ventilation course. Madrid. 2011
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!!!
DRIVING PRESSURE In both situations the plateau pressure is = 30 cmh2o PEEP of 5 cm H 2 0 PEEP of 10 cm H 2 0 Driving pressure of 25 cmh2o Driving pressure of 20 cmh2o Positive End-Expiratory Pressure after a Recruitment Maneuver Prevents Both Alveolar Collapse and Recruitment/Derecruitment Jeffrey M. Halter, Jay M. Steinberg, Henry J. Schiller, Monica DaSilva, Louis A. Gatto, Steve Landas, and Gary F. Nieman Am J Respir Crit Care Med 2003;167: 1620 1626,
Conclusions Driving 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 reintubation 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 cmh 2 O / 40 seconds NEVER in children (bradycardia). 2. Few cycles at high pressure: 4-6 cycles 50 cmh 2 O. NEVER in children (barotrauma risk). 3. PCV with constant driving pressure y PEEP: Fixed driving pressure of 15 cmh 2 O Positive end-expiratory pressure (PEEP) was incrementally increased by steps of 5 cmh 2 O from ZEEP to a PEEP of 20-30 cmh 2 O. Decrement PEEP titration in steps of 2 cmh 2 O 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 PCV Driving Pressure 15 cmh2o 20 25 30 40 (45-60)Collapse point: 35 Reduce of Cdyn + Lung 15 5 10 15 VCV for a driving pressure < 15 cmh2o 20 20 protective ventilation
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; obese patients and laparoscopic procedures indivudualice sometimes even more than 15 cmh2o.
Automatic Recruitment Manouvers
Protective ventilation 1. 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)
Protective ventilation 5. Individualize the oxygenation and hypercapnia level in each patient each day (Permissive or adaptive hypercapnia for ph > 7,2) 6. FiO 2 < 0.7 TIMING IS CRUTIAL (THERAPEUTIC WINDOW) (MOST 7. Fluid balance: OF THIS restricted ACTIONS WORK WELL IF YOU APPLY 8. PronoTHEM sometime WITHIN helps improving THE V/Q FIRST before 2 ECMO DAYS in ARDS OF THE ONSET OF ARDS) 9. Induced hypothermia: (34-35º C) and paralysis in extreme difficult ventilate situations 10. Mechanical assistant devices: CO 2 removal systems or respiratory ECMO as final rescue therapy
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