Mechanical Ventilation: A Primer (How to save a life when I’m alone in the middle of the night)
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Transcript of Mechanical Ventilation: A Primer (How to save a life when I’m alone in the middle of the night)
Mechanical Ventilation: A Primer(How to save a life when I’m alone in the middle of the night)
Nick Mohr, MDAssistant Professor
Department of Emergency MedicineDivision of Critical Care, Department of Anesthesia
University of Iowa Carver College of Medicine
Objectives• To review basic mechanical ventilation theory and
terminology• To define an algorithmic approach to mechanical
ventilation in the emergency department• To explore algorithms for troubleshooting ventilation
and oxygenation problems• To discuss specific clinical scenarios requiring
specialized ventilation strategies
Conflicts of Interest• This speaker has no financial relationships to
disclose.
• Topics discussed in this lecture are a component of the University of Iowa Visiting Professor Program Conference Series.
• The content of this lecture was developed following an extensive literature search and contains up-to-date, evidence-based information.
Basic Mechanical Ventilation
Ventilation Mechanics: Inflection Points, Loops, SynchronyAdvanced Strategies: Triggering, PRVC/VC+Ventilation Adjuncts: Proning, Inhaled Vasodilators, HelioxRescue Modes: APRV, HFOV
% P
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What is the goal of mechanical ventilation?
Definitions
Definitions
Modes of Ventilation• Assist-Control (A/C)
– Volume Control (VC)
– Pressure Control (PC)
– Pressure Regulated Volume Control (PRVC/VC+)
• Synchronized Intermittent Mandatory Ventilation (SIMV)
• Pressure Support Ventilation (PSV)
Definitions
Ventilator Terminology
• PEEP
pPEEP
t
Definitions
Ventilator Terminology
• PEEP• Tidal Volume• FiO2
• Respiratory Rate– Set vs. actual
• Peak Pressure• Plateau Pressure
p t
peakplateau
Definitions
Tidal Volume
Respiratory Rate
FiO2PEEP
“Lung Protection”
“Ventilation” “Oxygenation”
Definitions
Determann RM. et al. Crit Care 2010;14:R1
Algorithm
Mascia L. et al. JAMA 2010;304:2620-7.
Algorithm
Ventilation Algorithm
Courtesy Scott Weingart, MD
Algorithm
Successful Intubation
Lung Protection Strategy
Obstructive Lung Disease
1. Select ventilation strategy
Algorithm
Successful Intubation
Lung Protection Strategy
Obstructive Lung Disease
1. Select ventilation strategy
Algorithm
IBWmale (kg) = 50 + (2.3 x h(over 5 ft)(in))
IBWfemale (kg) = 45.5 + (2.3 x h(over 5 ft)(in))
2. Calculate ideal tidal volume
Goal volume 6 mL/kg
Algorithm
Image courtesy JustPressPlay®
Height Male Female5 ft 2 in 350 350
5 ft 5 in 400 400
5 ft 8 in 450 450
5 ft 11 in 500 500
6 ft 2 in 550 500
6 ft 5 in 600 550
6 ft 8 in 650 600
Algorithm
Algorithm
How well do we practice low tidal volume ventilation in the ED?
Fuller BM. et al. Acad Emerg Med 2013;20:659-69.
3. Select respiratory rate
Try to match required minute ventilation
Usually start at 14-18 breaths/minute
Check a blood gas
Algorithm
4. Select oxygenation parameters
Start all ventilated patients at FiO2 = 100%
Wean aggressively
Algorithm
Why add PEEP?
Algorithm
Volu
me
Pressure
Algorithm
Volu
me
Pressure
PEEP
Algorithm
Volu
me
Pressure
PEEP
Algorithm
Bendixen HH. et al. N Engl J Med 1963;269:961-6
AIRPulmonary artery
Pulmonary vein
SHUNT
Algorithm
Slutsky AS. et al. NEJM 2006;354:1839-41
Algorithm
Why add PEEP?• Decrease shunt• Prevent atelectasis• Increase mean airway
pressure
FiO2 PEEP
30% 5
40% 5
40% 8
50% 8
50% 10
60% 10
70% 10
70% 12
70% 14
80% 14
90% 14
90% 16
90% 18
100% 18-24
Brower RG. et al. N Engl J Med 2000;342:1301-8
Algorithm
peakplateau
P
P
alveoli
ventilator
5. Limit plateau pressure
Algorithm
6. Check blood gas, reassess
Check ABG/VBG at 15-30 minutes
Correlate with EtCO2
Algorithm
Volu
me
Pressure
Plateau Pressure ≤ 30 cm H20
Tidal volume 6 – 8 mL/kg
PEEP set to limit atelectasis and shunt
(PEEP table)
Minimize FiO2
Lung Protective Ventilation
Algorithm
Goal-Directed Ventilation
MAP ≥ 65 pH ≥ 7.15
FiO2 ≤ 60%VT < 8 mL/kgpplateau < 30 pO2 ≥ 60
ComfortSedation
Pain Control
Algorithm
Lung Protective Ventilation1. Start with A/C (VC), sedation/pain control
2. Set tidal volume (6 – 8 mL/kg IBW)
3. Adjust respiratory rate for ventilation
4. Set FiO2 at 100% and wean aggressively
– Titrate PEEP to necessary FiO2 (table)
5. Check plateau pressure (goal < 30)
6. Check blood gas and titrate
Algorithm
How does ventilation differ in patients with obstructive lung
disease?
Algorithm
P
Flow
Flow does not return to zero
Peak pressure rises
“Air trapping”
Algorithm
Normal lungsObstructive Lung Disease
Algorithm
Marini. et al. Critical Care Medicine: The Essentials, 1997
Normal Abnormal
Flow
“Rest” “No Silence”
Algorithm
Tidal Volume
Respiratory Rate
FiO2PEEP
“Lung Protection”
“Ventilation” “Oxygenation”
Protection
Algorithm
Successful Intubation
Lung Protection Strategy
Obstructive Lung Disease
1. Select ventilation strategy
Algorithm
IBWmale (kg) = 50 + (2.3 x h(over 5 ft)(in))
IBWfemale (kg) = 45.5 + (2.3 x h(over 5 ft)(in))
2. Calculate ideal tidal volume
Goal volume 8 mL/kg
Algorithm
3. Select respiratory rate
Try to meet ventilatory demands
Start at 8 breaths per minute
Reassess at bedside – look at flow loop
THIS IS THE MOST EFFECTIVE WAY TO KILL A SEVERE ASTHMATIC WITH THE VENTILATOR
Algorithm
4. Select oxygenation parameters
Start all ventilated patients at FiO2 = 100%
Wean aggressively
These patients probably will not require high FiO2 levels
Algorithm
5. Set PEEP
Start low (PEEP 0 okay)
Keep it low
Algorithm
peakplateau
P
P
alveoli
ventilator
6. Limit plateau pressure
Recheck frequently
Algorithm
7. Check blood gas, reassess
Check ABG/VBG at 15-30 minutes
Correlate with EtCO2
pH ≥ 7.10 – 7.15 is good enough in most circumstances
Algorithm
Goal-Directed Ventilation
MAP ≥ 65 pH ≥ 7.15
FiO2 ≤ 60%VT < 8 mL/kgpplateau < 30 pO2 ≥ 60
ComfortSedation
Pain Control
Algorithm
Obstructive Lung Disease Ventilation
1. Start with A/C (VC), sedation/pain control (deep)
2. Set tidal volume (8 mL/kg IBW), higher for ventilation
3. Keep respiratory rate low
4. Set FiO2 at 100% and wean aggressively
– Use PEEP 0 - 5
5. Check plateau pressure (goal < 30), no air trapping
6. Check blood gas and titrate
Algorithm
Troubleshooting the Ventilator
Troubleshooting
Failures of Mechanical Ventilation
Hypoxia
Hemodynamic Instability
Troubleshooting
Hypoxia on the Ventilator
islodgementDOPE
EtCO2
Direct Visualization
Fiberoptic Bronchoscopy
Troubleshooting
Hypoxia on the Ventilator
islodgement
bstruction
DOPE
Pass suction catheter
Lavage
Replace ETT
Troubleshooting
Hypoxia on the Ventilator
islodgement
bstruction
neumothorax
DOPE
Bilateral breath sounds
Tracheal deviation
Ventilator peak pressures
Troubleshooting
Hypoxia on the Ventilator
islodgement
bstruction
neumothorax
quipment failure
DOPE
Bag-valve on FiO2 100%
Use PEEP valve
Check ventilator
Troubleshooting
Hypoxia on the Ventilator
islodgement
bstruction
neumothorax
quipment failure
DOPE
Troubleshooting
Failures of Mechanical Ventilation
Hypoxia
Hemodynamic Instability
Troubleshooting
Sudden Cardiovascular Collapse
Post-IntubationInduction
Loss of sympathetic
tone
Right heart dysfunction
Volume depletion
New OnsetTension PTX
Breath stacking/Air
trapping
Excessive PEEP
Hypoxia/vagal
Image courtesy Department of Environmental Health, Pitkin County, Colorado
Troubleshooting
Sudden Cardiovascular Collapse
Post-IntubationFluid bolus
Vasopressor
BV slowly, unless
intubated for acidemia
New OnsetDisconnect
the ventilator
Look for tension PTX
BV slowly, turn down PEEP
Image courtesy Department of Environmental Health, Pitkin County, Colorado
Troubleshooting
Cases
Cases
Case 1
84 y/o f (height 5’11”) with UTI presents with hypotension (BP70/30), tachycardia (P135), fever (T39.1 C), and unresponsiveness
You decide to intubate.Ventilator settings?
Cases
Lung Protective Ventilation1. Start with A/C (VC), sedation/pain control
2. Set tidal volume (6 – 8 mL/kg IBW)
3. Adjust respiratory rate for ventilation
4. Set FiO2 at 100% and wean aggressively
– Titrate PEEP to necessary FiO2 (table)
5. Check plateau pressure (goal < 30)
6. Check blood gas and titrate
Cases
Case 229 y/o m (height 5’11”) with h/o asthma
presents by ambulance after waking up unable to breath. He is no longer arousable.
P160 BP180/110 RR52 FiO2 86%
You decide to intubate.Ventilator settings?
Cases
Obstructive Lung Disease Ventilation
1. Start with A/C (VC), sedation/pain control (deep)
2. Set tidal volume (8 mL/kg IBW), higher for ventilation
3. Keep respiratory rate low
4. Set FiO2 at 100% and wean aggressively
– Use PEEP 0 - 5
5. Check plateau pressure (goal < 30), no air trapping
6. Check blood gas and titrate
Cases
Case 368 y/o m with h/o COPD was involved in
MVC and was intubated on arrival. While he is returning from CT 25 minutes later, he becomes hypoxic to 60% and bradycardic.
What is your intervention?
Cases
Hypoxia on the Ventilator
islodgement
bstruction
neumothorax
quipment failure
DOPE
Cases
Case 449 y/o f intubated for severe COPD at OSH
is transferred for ICU care. As EMS arrives, they are starting chest compressions.
What is your intervention?
Cases
Sudden Cardiovascular Collapse
Post-IntubationFluid bolus
Vasopressor
BV slowly, unless
intubated for acidemia
New OnsetDisconnect
the ventilator
Look for tension PTX
BV slowly, turn down PEEP
Image courtesy Department of Environmental Health, Pitkin County, Colorado
Cases
Summary• Thou shalt not fear mechanical ventilation. Most
problems in the ED can be resolved with sedation, respiratory rate, and FiO2
• Thou shalt not use injurious ventilatory strategies (low tidal volume)
• Thou shalt not code an asthmatic on the ventilator (low respiratory rate/air trapping)
• Maintain an algorithmic approach to critically ill patients, then think about the physiology
Mechanical Ventilation: A Primer
Nick Mohr, MDAssistant Professor
Department of Emergency MedicineDivision of Critical Care, Department of Anesthesia
University of Iowa Carver College of Medicine