Course Materials

   

  Management Strategies for the Mechanically Ventilated Patient AARC Current Topics in Respiratory Care 2015 Program 2 – CT20152 ®

Approved for 1 contact hour of CRCE credit per participant who successfully completes the test.

© 2015 American Association for Respiratory Care

OVERVIEW Management Strategies for the Mechanically Ventilated Patient AARC Current Topics in Respiratory Care 2015 – Program 2

Description § Part 1: Evaluation of dead space ventilation may be an important tool to help clinicians when determining certain ventilator strategies. Does it have a role in optimizing PEEP? Does it predict mortality? This presentation will discuss these topics and help us understand how the use of capnography may help guide the way. § Part 2: A discussion of PEEP titration in the setting of refractory hypoxemia and the role of recruitment maneuvers. Included will be use of oxygenation tables, best compliance, stress index, and esophageal manometry.

Objectives Part § § § Part § § § § §

1: Discuss the history of measuring deadspace in the ICU Define and describe volumetric capnography Describe the prognostic value of deadspace measurements 2: Should an open lung approach be used (recruitment maneuvers and decremental PEEP)? What does the evidence support for use of PEEP in ARDS? What are approaches that can be used to set PEEP in ARDS? Which is the best strategy for setting PEEP? What are the benefits of PEEP other than ARDS?

Lecturer Richard Kallet, MS, RRT, FAARC Director of Quality Assurance Respiratory Care Services UCSF at San Francisco San Francisco, California

Dean Hess, PhD, RRT, FAARC Assistant Director, Respiratory Care Massachusetts General Hospital Associate Professor of Anesthesia Harvard Medical School Boston, Massachusetts Editor-in-Chief, RESPIRATORY CARE Journal CRCE® Credit To earn 1 CRCE credit for participating in today’s program: • View entire presentation • Take the 10-question test (available from Proctor/Site Coordinator) • Answer at least 7 questions correctly • Enter your name and AARC member number on the Attendance and CRCE Log (Please do not enter your Social Security Number) • Receive Certificate of Completion from the Proctor/Site Coordinator

   

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PROGRAM SLIDES and NOTES

Slide 1 Part 1: THE USE OF CAPNOGRAPHY TO DETERMINE PHYSIOLOGIC DEADSPACE AND GUIDE MANAGEMENT OF MECHANICAL VENTILATION

Richard Kallet, MS, RRT, FAARC Director of Quality Assurance Respiratory Care Services UCSF at San Francisco San Francisco, California

Slide 2

Objectives • Discuss the history of measuring deadspace in the ICU • Define and describe volumetric capnography • Describe the prognostic value of deadspace measurements

   

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Slide 3

Why Measure Vd/Vt during Mechanical Ventilation? • Clinically easy to measure • Marker of disease severity and outcome

• Signifier of lung recruitment / de-recruitment • Signifier of lung over-distension • Provides useful information for weaning

Slide 4

Brief History of Dead-Space Measurements in the ICU

Slide 5

1960’s-1980’s • Douglas Bag: collection of expired VT for 3-5min into a large plastic or rubber bag or weather balloon (resistant to CO2 diffusion). • 1pt measurement of PECO2 • Required valving system, syringe sampling for ABG machine, or mass spectrometry • Prone to operator error • Laborious • Variable significant overestimation error from effects of high PIPs on compression volume contamination • Required either mathematical correction or parallel isolation circuit that altered ventilator performance

   

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Slide 6

Measurements: 1990’s • Metabolic Cart Measurements • Facilitated ease of measurement. • Virtually eliminated sources of operator error • Still required correction for compression volume contamination. • Correction Formula: PECO2 x [VT/(VT – Vcompr)]

• Vcompr = (PIP-PEEP) x Ccircuit

Slide 7

Early  2000’s:  Volumetric  Capnopgraphy Combined CO2 sensor & pneumotachograph allows Integration of expired volume with expired CO2 concentration. Eliminated compression volume problem Real time graphic display Minute-to-minute averaging of CO2 and pulmonary mechanics Measuring VD/VT, VCO2, estimation of PCBF

Correction Factors for Vd/Vt have acceptable accuracy

   

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Slide 8

   

Slide 9

What Volumetric Capnography Reveals About Lung Function

VD/VT Reflects a More Complete Picture of Lung Injury than Oxygenation

Slide 10

• CO2:  is  ~20  times  more  “diffusible  across  tissues  than  O2 because of its > solubility. • Principles of MIGET: – low solubility gases: “diffusion  sensitive”    differentiate shunt from low V/Q – High solubility gases: “perfusion  sensitive”  differentiate high V/Q from dead-space

• O2 & CO2 (intermediate solubilities) follow same principle • Bohr-Enghoff Eq uses PaCO2 as a surrogate for PACO2 the equation “crosses  the  barrier”    becoming  a   perfusion variable influenced by shunt

Slide 11

VD/VT Reflects: • True Dead-Space

• V/Q Inhomogeneity

• Shunt

   

Strongly Perfusion Sensitive Reflects both overdistension & vascular injury Signifier of PHTN in ARDS Mortality Link with R Heart Strain-Cor Pulmonale

Somewhat Diffusion Sensitive To a Lesser Degree than O2 reflects edema ,consolidation

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Moderate Weak Correlation between Indices for Oxygenation & Ventilation in ARDS

Slide 12

r = -0.39 r2 = 0.15

0.86 0.819 0.778 0.737

VD/VT

0.696

Vd/Vt

0.655 0.614 0.573 0.532 0.492 0.451 0.41 0.369 50

100

150

200

250

PaO2/FiO2 PaO2 /FiO2

Slide 13

Fowler:Fletcher Analysis of Volumetric Capnography

VT E

Bulk Gas Flow

Gas Diffusion

Slide 14

Fowler Idealized 2-Compartment Model: Single Alveolus: Single Airway

Expired VT

   

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Slide 15

Fowler:Fletcher Analysis of Volumetric Capnography

VDAW

VDALV

VCO2br

Phase 1: Pure airway dead-space Phase 2: Transition: airway + alveolar gas (Slope ~ expiratory time constant distribution) Phase 3: Alveolar Plateau (Slope ~ V/Q distribution)

Slide 16

Quick Analysis of Abnormal Curves Increasing Slope of Phase III Predominant V/Q Mismatch

Normal: Very subtle Phase III slope

Gradual Slope of Phase II: Loss of inflection point at the junction of Phase II & Phase III: Unequal lung emptying vs. high alveolar dead-space (or both) & V/Q mismatch

Very Severe Pulmonary Disease

Slide 17

Patient-Ventilator Asynchrony: Effect of Uncaptured Efforts on Capnography Tracing

Look at expired flow scalar tracing

   

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Slide 18

FECO2

Artifact with Expired Aerosol or Condensate in the Cuvette

Volume signal intact, temporary loss of CO2 detection. Seen early expiration w/ Aerosolized Prostacyclin

Volume

Slide 19

VCO2 • • • •

CO2 excretion / min Health VCO2 ≈  CO2  Production  (steady state) Pulmonary disease CO2 Production CO2 excretion from body stores depends upon adequacy of systemic perfusion (particularly muscle perfusion) • Human  body’s  capacity to store CO2 ~20 L (11.6 mL/kg per 1 mmHg change in PaCO2). • Under  normal  physiologic  conditions  a  “true”  CO2 steady state is considered rare. • Pulmonary Factors that limit extrapolating CO2 production from CO2 excretion: Vd/Vt, V/Q, Qs/Qt, cardiac output: SVR (i.e. peripheral vasomotor function)

Slide 20

Can VD/VT be Estimated Rather than Measured? NO! 406 Comparisons of Calculated VD/VT (Harris Benedict Equation) vs. Measured VD/VT

0.901

R = 0.68, R2 = 0.46 p < 0.0001

0.86 0.819 0.778 0.737 0.696 0.655 Vd-Vt_HB

0.614 0.573 0.532 0.492 0.451 0.41 0.369 0.328 0.287 0.246 0.328 0.348 0.369 0.389 0.41 0.43 0.451 0.471 0.492 0.512 0.532 0.553 0.573 0.594 0.614 0.635 0.655 0.676 0.696 0.717 0.737 0.758 0.778 0.799 0.819 0.84 0.86 0.881 0.901 0.922 Vd/Vt

   

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What Comparisons Between Methods Measuring the Same Variable Should look Like:

r2 = 0.88 0.89

Slide 21

r2 = Respir Care 50: 2005

Slide 22

Dead-Space and Mortality

VD/VT & Mortality Risk Over Time during Traditional VT Ventilation

Slide 23

Respir Care 49:2004

   

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Slide 24

ARDS Net VD/VT Study p = 0.08

p=0.01

p = 0.004

0.8

0.7 0.6

0.67

0.64

0.62 0.56

0.56

0.55

0.5 0.4 0.3 0.2 0.1 0 Day-0

Day-1

Survivors Fig 2. Dead-space

Day-2

Non Survivors

fraction and outcome by study day.

Respir Care 2014

Slide 25

Mortality Risk • Nuckton Study: risk of death by 45%for 0.05 in VD/VT (RR = 1.45) on Day of ARDS Onset • ARDS Net Study: for every 0.10 risk of death increased by:

in VD/VT the

– 59% (RR: 1.54) on Day of Enrollment* – 94% (RR: 1.94) on Study Day 1 – 250% (RR: 2.50) on Study Day 2 • * Enrollment window for ARDS Net: 36h from onset with all baseline measurements done by 48h

Does High VD/VT During Traditional VT Ventilation (10mL/kg) have the Same Significance in the LPV Era?

80%

70%

73%

77%

64%

70%

50%

60%

Slide 26

50% APACHE II 28

50% 40% 30% APACHE II 24

20% 10% 0%

%VD/VT

Act-Mort TMV

Pred-Mort LPV

Nuckton Data from SFGH vs. QA Data from SFGH VD/VT > 0.65

   

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Slide 27

Assessing the Effects of Therapy Using Dead-Space

Slide 28

VD/VT Reflects Pulmonary Perfusion: Effects of APC Rx (APC d/c @ 41hr for GI bleed)

Respir Care 55;2010

Slide 29

VD/VT Reflects Pulmonary Perfusion: Effects of Corticosteroid Rx in ARDS

Raurich 2012

   

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Slide 30 Using VD/VT to Select Optimal PEEP during PEEP Decrement Trial

Slide 31 Perfusion Sensitive VD/VT Detects De-recruitment Before Deterioration in Oxygenation Becomes Apparent

Tusman 2006

Lung recruitability with PP in ARDS has stronger association with PaCO2 than PaO2/FiO2

Slide 32

Protti, Intesive Care Med 2009

   

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Slide 33

Effects of adding RM to PP • ARDS Case 2 • 39yo obese male aspiration (SpO2 = 60% on RA) • Day 9 ARDS: Lobar collapse: prolong trendelenburg (PAC) • FiO2:1; PEEP: 16; Crs: 27 mL/cmH2O, VT: 7.4 VE: 11.8 L/m; • Aeroprost 50 ng/kg/m; • RM PC 45/25 x 3min • Resulting ABG: 7.51/41/63 VD/VT = 0.60

ARDS Case 2 PP + RM

0.80 0.70

Slide 34

0.77

0.64 0.60

0.60

0.57

0.55

0.56 0.49

0.50 0.40 0.30 0.19

0.20 0.10

0.08

0.10

0.07

* 0.00 SP-1

P/F 56 PEEP +14

SP-RM

63 +16

PP

P-RM

A/aPO2

VD/VT

49* +16

P-RM4h

128 50/30

P-RM-10h

328 50/30

504 50/30

Watching Lung Recruitment with Volumetric Capnography

Slide 35

PCV 35/15: P/F = 49 PCV 40/20 PCV 45/25 PCV 50/30: P/F = 328

   

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Slide 36

VD/VT & Probability of Extubation Failure

Gonzales-Castro 2011

Slide 37

Summary • VD/VT: a more complete picture of lung pathology, particularly in ARDS • Mortality: Combination of VILI: Overdistension, Vascular Injury & Cor Pulmonale • Perfusion Sensitivity: Early Signal for Detecting Lung Recruitment & De-recruitment • Cannot be accurately estimated by HB Equation • May be a good tool for assessing extubation failure risk

Slide 38

Part 2: PEEP AND RECRUITMENT MANEUVERS Dean Hess, PhD, RRT, FAARC Assistant Director, Respiratory Care Massachusetts General Hospital Associate Professor of Anesthesia Harvard Medical School Boston, Massachusetts Editor-in-Chief, RESPIRATORY CARE

   

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Slide 39

Objectives • Should an open lung approach be used (recruitment maneuvers and decremental PEEP)? • What does the evidence support for use of PEEP in ARDS? • What are approaches that can be used used to set PEEP in ARDS? • Which is the best strategy for setting PEEP? • What are the benefits of PEEP other than ARDS?

Slide 40

Slide 41

Avoid over-distention (limit tidal volume and plateau pressure)

   

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Slide 42

Avoid over-distention (limit tidal volume and plateau pressure)

Avoid derecruitment (adequate PEEP)

Slide 43

Open Lung Approach • Tidal volume 6 mL/kg IBW • Recruitment maneuver • Decremental PEEP titration Prioritizes recruitment Assumes high potential for recruitment Potential for over-distention

Slide 44

Recruitment Maneuvers • A recruitment maneuver is a sustained increase in airway pressure with the goal to open collapsed lung tissue. • A popular recruitment maneuver has been a breath hold of 40 cm H2O for 40 seconds. • “Given  their  uncertain  benefit,  and  the   potential for complications with repeated application, the routine use of sustained inflation  RMs  is  not  justified.”  Fan et al, Respir Care 2012;57:1842

   

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Slide 45

Recruitment Maneuvers • “Clinicians  are  well  advised  to  relegate  this   once useful clinical tool to the growing archive of historically instructive but now obsolete methodologies.”   • Stepwise approaches to the maximum applied pressure are perhaps more effective than abrupt applications of the same peak pressure, and the graded rise of mean pressure is generally better tolerated. Marini, Intensive Care Med 2011;37:1572

Slide 46

Systematic Review And Meta-analysis

“The  quality of the current evidence is low and insufficient in terms of allowing for definitive and reliable conclusions. Thus, further research is likely to impact our confidence in the estimate of the effect and may change the estimate.” Suzumura, Intensive Care Med 2014;40:1227

Slide 47

Are Recruitment Maneuvers Safe?

   

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Slide 48

24-yr-old with H1N1; 6 h Post Intubation 5 cm H2O PEEP increments at 2 - 5 min on cisatricurium VT

PEEP Pplat

30 0

10

25

Pplat PEEP 15

30 0 30 0 30 0

15

29

20

22 0

SpO2 FIO2 CVP 79

1.0

20

14

79

1.0

---

33

13

80

1.0

---

25

39

14

96

1.0

14

20

30

10

96

0.6

12

Slide 49

Decremental PEEP Studies

Piraino, Respir Care 2013;58:886

Slide 50

14/0

45/10

45/0

Higher PEEP Lower Tidal Volume

Webb and Tierney, Am Rev Respir Dis 1974;110:556

   

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Slide 51

Higher vs. Lower PEEP • VT 6 mL/kg PBW; 2 PEEP levels • ALVEOLI (Brower, N Engl J Med 2004;351:327) – Oxygenation better with higher PEEP – Stopped early at 549 patients for futility • LOVS (Meade, JAMA 2008;299:637) – Less hypoxemia and use of rescue therapies – No significant difference in hospital mortality • EXPRESS (Mercat, JAMA 2008;299:646) – Improved lung function, reduced duration of mechanical ventilation and organ failure – No significant difference in mortality

Slide 52

Pplat/PEEP (cm H2O)

30 6 mL/kg 6 mL/kg

20 6 mL/kg

Injury > Benefit

10

0

Lower PEEP

Benefit > Injury Higher PEEP

Slide 53 Patients with moderate/severe ARDS

Patients with mild ARDS

Patients with moderate/severe ARDS

Patients with mild ARDS

Briel, JAMA 2010;303:865

   

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Slide 54 AJRCCM 2014;190:70

Slide 55 AJRCCM 2014;190:70

Slide 56 AJRCCM 2014;190:70

   

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Slide 57 AJRCCM 2014;190:70

Slide 58 AJRCCM 2014;190:70

non-recruitable

recruitable

Slide 59

How to Seat PEEP • Gas exchange – Oxygenation: PEEP/FIO2 tables – Dead space

• Respiratory mechanics – Compliance (lowest Pplat – PEEP) – Pressure-volume curve – Stress index – Transpulmonary pressure (esophageal balloon)

• Imaging – Chest CT – EIT – Ultrasound

   

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Slide 60

Mild ARDS:

Moderate to Severe ARDS

SpO2 88 – 95%

Slide 61

Suter, N Engl J Med 1975;292:284

Optimal PEEP by Tidal Compliance

C = VT / (Pplat – PEEP) Titrate PEEP to lowest Pplat – PEEP Highest PEEP for Pplat 28 – 30 cm H2O Mercat, JAMA 2008;299:646

↑  PEEP

Slide 62

Stress Index over-distention

Grasso, AJRCCM 2007;176:761

tidal recruitment

   

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Slide 63

PEEP = 8 cm H2O SI = 0.75 Pplat = 20 cm H2O

PEEP = 10 cm H2O SI = 1.38 Pplat = 35 cm H2O

PEEP= 18 cm H2O SI = 0.97 Pplat = 28 cm H2O

PEEP= 0 cm H2O SI = 1.06 Pplat = 15 cm H2O

Slide 64

Slide 65

   

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Slide 66

Slide 67

Esophageal Manometry

esophagus

pleura

Benditt, Respir Care 2005;50:68 Piraino and Cook, Respir Care 2011;56:510

49 year old male, acute pancreatitis, transferred from outside hospital for ECMO due to hypoxemic respiratory failure. Firm abdomen. Bladder pressure 21 mm Hg (28 cm H2O).

Slide 68

PEEP 28 cm H2O

Transpulmnary Pressure 3 cm H2O

SpO2 98%, FIO2 weaned to 0.4, PaO2 76 mm Hg

   

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Slide 69

Transpulmonary pressure (stress): 10 cm H2O

Slide 70

Stress Index

Slide 71

Which is Best? Table

Compliance

Stress Index

Esophageal Pressure

Chiumello, Crit Care Med 2014;42:252

   

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Slide 72

Setting PEEP for ARDS • 0 cm H2O: likely harmful • 8 – 12 cm H2O for mild ARDS; 12 – 16 cm H2O for moderate ARDS; 16 – 20 cm H2O for severe ARDS • > 20 cm H2O: seldom necessary • High PEEP should be reserved for cases where benefit outweighs harm • PEEP should be selected in the context of prevention of ventilator-induced lung injury • The benefit of precise PEEP is unproven

Slide 73

Benefits of PEEP • Maintain alveolar recruitment

Slide 74

Benefits of PEEP • Maintain alveolar recruitment • Counterbalance auto-PEEP

   

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Slide 75

Benefits of PEEP • Maintain alveolar recruitment • Counterbalance auto-PEEP • Reduce preload and afterload

Slide 76

Benefits of PEEP • • • •

Maintain alveolar recruitment Counterbalance auto-PEEP Reduce preload and afterload Splint airway with tracheomalacia

Slide 77

Benefits of PEEP • • • • •

   

Maintain alveolar recruitment Counterbalance auto-PEEP Reduce preload and afterload Splint airway with tracheomalacia Prevent ventilator-associated pneumonia

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Slide 78

Benefits of PEEP • • • • • •

Maintain alveolar recruitment Counterbalance auto-PEEP Reduce preload and afterload Splint airway with tracheomalacia Prevent ventilator-associated pneumonia Speech with tracheostomy cuff deflated

Slide 79

PEEP is good!

Slide 80

PEEP is good! …  But  must  be  used  wisely!!

   

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TEST Management Strategies for the Mechanically Ventilated Patient AARC Current Topics in Respiratory Care 2015 – Program 2 Mark the Corresponding Box for your Response to each Question 7 Correct Out of 10 is Passing

Name: __________________

_____________________

AARC Mbr #: _______________

Email Address:___________________________________

Date: _____________________

(first)

(last)

(required for nonmembers)

1. The measurement of Vd/Vt during mechanical ventilation is a signifier of lung overdistension. o True o False 2. Volumetric capnography, though an advancement in capnography, failed to eliminate the compression volume problem. o True o False 3. Phase II of capnography is reflective of gas diffusion. o True o False 4. It is better to perform measurements with a clean cuvette, removing condensate. o True o False 5. The respiratory therapist notes that there is a loss of inflection point on the capnography curve at the junction of Phase II and Phase III. This could be caused by high alveolar deadspace. o True o False 6. An open lung approach is a safe and consistent strategy for alveolar recruitment. o True o False 7. The evidence does not support the use of PEEP over 10 cm H2O in ARDS. o True o False 8. PEEP can reduce preload and afterload, when applied appropriately. o True o False 9. An incremental PEEP titration can be useful in improving oxygenation. o True o False 10. To avoid overdistension of the alveoli, one must limit the tidal volume and plateau pressure. o True o False

   

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PARTICIPANT EVALUATION Management Strategies for the Mechanically Ventilated Patient AARC Current Topics in Respiratory Care 2015 – Program 2

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_____RT Supervisor/Mgr

_____Student

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_____Other (please specify) ________________________________________________ 2. The content of today’s program was relevant and applicable to my job. _____Strongly Disagree _____Disagree _____Neutral _____Agree _____Strongly Agree 3. Presenters were easily understood and presented the topic well. _____Strongly Disagree _____Disagree _____Neutral _____Agree _____Strongly Agree 4. Slides on the video were effective in supporting the information presented. _____Strongly Disagree _____Disagree _____Neutral _____Agree _____Strongly Agree 5. I achieved the learning objectives of today’s program. _____Strongly Disagree _____Disagree _____Neutral _____Agree _____Strongly Agree 6. Provide any comments you have about this program:

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