mech vent

1. Introduction to Mechanical
Ventilation at UT Southwestern
Jonathan C. Weissler M.D.
Chief of Medicine, UT Southwestern
University Hospitals
Professor and Vice Chairman, Department of
Internal Medicine
University of Texas Southwestern Medical
Center

2. Ventilators in UTSW System
Parkland: Servo-1 (Maquet)

3. Ventilators in UTSW System
CUH, VA : Puritan Bennett 840

4. Modes of Ventilation
Volume Control
The machine guarantees a minimum tidal
volume with each delivered breath regardless
of the pressure necessary to deliver it (as long
as limits are not exceeded)
Pressure Control
The machine delivers a set pressure with
each breath, tidal volumes vary and are not
guaranteed.

5. Modes of ventilation
Mode of ventilation:
Volume Control
Assist Control (CMV) –every breath full
support
SIMV- mandated breaths plus unsupported
extra breaths– NOT APPROPRIATE IN
MOST MICU PATIENTS

6. Setting Up the Ventilator
1. FiO2
2. Tidal Volume
3. Rate
4. I:E ratio
5. PEEP
6. Alarms
7. Sedation/Paralysis

7. FiO2
1.0 (100%) in most cases
EXCEPT
History of Bleomycin, Amiodarone (risk of
oxidant mediated lung injury)

8. Tidal Volume
General Principles:
Normal lungs (neuromuscular disease only, head
trauma): 10cc/kg PBW (~700 cc)
ARDS/ALI, bad pneumonia: 6-7 cc/kg PBW (~375-
425 for men, 300-325 for women)
Asthma/COPD: 375-425 cc

9. Compliance Curve

10. Compliance Curve in ARDS
(Am J Resp Crit Care Med 1995,152:121-8)

11. Percent of ARDS Patients Exceeding the
UIP with Increasing VT
(Am J Resp Crit Care Med 1995,152:121-8)

12. Tidal Volume
General Principles:
Normal lungs (neuromuscular disease only, head
trauma): 10cc/kg PBW (~700 cc)
ARDS/ALI, bad pneumonia: 6-7 cc/kg PBW (~375-
425 for men, 300-325 for women)
Asthma/COPD: 375-425 cc

13. Low Tidal Volumes Improve Survival in
ARDS
(NEJM 2000, 342:1301-8)

14. How to Ventilate ARDSHow to Ventilate ARDS
Brower RG, et al. Am J Respir Crit Care Med 2002:166;1515-1517

15. Tidal Volume
General Principles:
Normal lungs (neuromuscular disease only, head trauma):
10cc/kg PBW (~700 cc)
ARDS/ALI, bad pneumonia: 6-7 cc/kg PBW (~375-425
for men, 300-325 for women)
Asthma/COPD: 375-425 cc

16. Assist Control
2. Rate
normal lungs 10-12
ARDS/pneumonia 24-28
asthma/COPD 7-8 UNLESS pCO2 >90
I:E ratio
Normal 1:3
ARDS 1:2
Asthma 1:6
Inspiratory time****
Flow rate 50-100 L/min, usually 50-60 L/min

17. Flow rate vs. no flow rate

18. Air Trapping Detected by Flow vs
Time Curve

19. Pay Attention to the Interaction
Between Tinsp, Rate, and I:E

20. Relationship of Mortality to
Oxygenation in 101 Studies of ARDS
(Intensive Care Med 1996, 22:519-29)

21. Relationship between FiO2 and pO2

22. Oxygenation
Palv (mean) ~= Ti/Te + PEEP +
auto PEEP

23. PEEP
Normal Lungs : 0-5 cm
ARDS: unclear, probably 8-10
Unless patient can’t be oxygenated; then 15-18
asthma/COPD : 0*
* until COPD patient is awake and
triggering ventilator
elevated CNS pressure :0**
** unless necessary for oxygenation

24. Peak Pressure Alarm
1. Peak pressure- when alarm sounds breath is
terminated.
2. Causes may be mucus plug, kinked tube,
pneumothorax, worsening compliance, or
patient “fighting the ventilator”.
3. Usually set at 50-60 mmHg; in a tight
asthmatic set at >80.

25. OK thanks for the reassurance that oxygenation
doesn’t correlate with survival BUT I Can’t
Oxygenate the Patient (sats <85% and dropping)
Call somebody and get a CXR
Bag the patient with a PEEP valve (10cm
or greater) attached
PEEP to increase mean pressure
Pressure control/APRV/Bilevel ventilation
Nitric Oxide
Prone ventilation
Oscillator/high frequency ventilator
ECMO

26. ECMO 2015
V-V ECMO removes CO2, can only send 3-5 L/min thru
the membrane so oxygenates better with lower cardiac
outputs, avoids some of the embolic complications of V-
A ECMO. Allows patients to ambulate pre-transplant.
CESAR trial in UK 2001-6: referral to single ECMO
center. Survival for those referred at 6 months 63% v
47% at tertiary care centers. Patients started on ECMO
at mean 35 hours ventilation (Int Care Med 2009)
ANZ ECMO (JAMA 2009) Salvage therapies (iNO, HFOV)
used in less than 30%, median days on vent ECMO 18 v
8 conventional, ICU days higher on ECMO (22 v 12),
ICU mortality higher (23% v 9%). Most patients started
on ECMO elsewhere then transferred to an ECMO
center

27. What to Follow in a Ventilated Patient
1. ABG- In a sick patient “the enemy of good is better”
2. pCO2- A significant rise with a constant or increased
minute ventilation is ALWAYS a bad sign
3. Plateau pressure- Keep it under 33-34, in ARDS change
to pressure limited ventilation
4. Air trapping
5. Patient comfort (synchrony)

28. Rapid Sequence Intubation
1. If patient has spinal cord injury or recent neck
surgery, or you anticipate a difficult airway you need
anesthesiology
2. Preoxygenate without bagging unless patient
hypoxic (sats<91%), if critically unstable bag and tube
3. Versed 2-4 mg IV over 30-60 seconds, Etomidate
20mg over 30-60 seconds, Succinylcholine 1mg/kg IV
over 30-60 seconds
Don’t use succ in patients with ALS,
Polio, or hyperkalemic

29. SedationSedation
 Usually a combination of an anxiolytic and anUsually a combination of an anxiolytic and an
analgesicanalgesic
 Parkland ICU: Morphine (or Fentanyl) andParkland ICU: Morphine (or Fentanyl) and
AtivanAtivan
 VA ICU/UHSP: Fentanyl and VersedVA ICU/UHSP: Fentanyl and Versed
 Alternative: Propofol (Diprivan)Alternative: Propofol (Diprivan)

30. SedationSedation
 Important principlesImportant principles::
 Always start with a loading dose followed a low-doseAlways start with a loading dose followed a low-dose
continuous infusion.continuous infusion.
 Any up titration of the continuous infusion shouldAny up titration of the continuous infusion should
be preceded by an additional loading dosebe preceded by an additional loading dose
 Avoid writing: “Morphine and Ativan drips—titrateAvoid writing: “Morphine and Ativan drips—titrate
to sedation”to sedation”
 Sedation holidaysSedation holidays

31. SedationSedation
 MorphineMorphine
 Loading dose: 2-5mg IV bolusLoading dose: 2-5mg IV bolus
 Initial infusion: 2-4 mg/hrInitial infusion: 2-4 mg/hr
 Titration:Titration:
 Reload with 2-5mg IV bolusReload with 2-5mg IV bolus
 Increase infusion by 1-2mg/hrIncrease infusion by 1-2mg/hr
 May repeat every 15-30 minutes as neededMay repeat every 15-30 minutes as needed
 Maximum: 20mg/hrMaximum: 20mg/hr

32. SedationSedation
 AtivanAtivan
 Loading dose: 2-4mg IV bolusLoading dose: 2-4mg IV bolus
 Initial infusion: 1-2 mg/hrInitial infusion: 1-2 mg/hr
 Titration:Titration:
 Reload with 2-4mg IV bolusReload with 2-4mg IV bolus
 Increase infusion by 1-2mg/hrIncrease infusion by 1-2mg/hr
 May repeat every 15-30 minutes as neededMay repeat every 15-30 minutes as needed
 Maximum: 10mg/hrMaximum: 10mg/hr

33. SedationSedation
 FentanylFentanyl
 Loading dose: 25-50 mcg IV bolusLoading dose: 25-50 mcg IV bolus
 Initial infusion: 25-50 mcg/hrInitial infusion: 25-50 mcg/hr
 Titration:Titration:
 Reload with 25 mcg IV bolusReload with 25 mcg IV bolus
 Increase infusion by 25 mcg/hrIncrease infusion by 25 mcg/hr
 May repeat every 15-30 minutes as neededMay repeat every 15-30 minutes as needed
 Maximum: 150-200mcg/hrMaximum: 150-200mcg/hr

34. SedationSedation
 VersedVersed
 Loading dose: 2-5mg IV bolusLoading dose: 2-5mg IV bolus
 Initial infusion: 2-4 mg/hrInitial infusion: 2-4 mg/hr
 Titration:Titration:
 Reload with 2-5mg IV bolusReload with 2-5mg IV bolus
 Increase infusion by 1-2mg/hrIncrease infusion by 1-2mg/hr
 May repeat every 15-30 minutes as neededMay repeat every 15-30 minutes as needed
 Maximum: 20mg/hrMaximum: 20mg/hr

35. SedationSedation
 Propofol (Diprivan)Propofol (Diprivan)
 Rapid onset/short duration of actionRapid onset/short duration of action
 Rapid Induction:Rapid Induction:
 20-40mg IV bolus Q 20 seconds until sedated20-40mg IV bolus Q 20 seconds until sedated
 Continuous infusion:Continuous infusion:
 Start 5-10 mcg/kg/minStart 5-10 mcg/kg/min
 Increase by 5-10 mcg/kg/min every 5-10 minutes untilIncrease by 5-10 mcg/kg/min every 5-10 minutes until
desired sedation (Max 100mcg/kg/min)desired sedation (Max 100mcg/kg/min)
 Adverse ReactionAdverse Reaction:: HypotensionHypotension, bradycardia, bradycardia

36. ParalyticsParalytics
 Bolus dosing:Bolus dosing:
 VecuroniumVecuronium (Norcuron) 0.08-0.1 mg/kg IV x 1(Norcuron) 0.08-0.1 mg/kg IV x 1
 Usual doseUsual dose 7-10mg IV bolus7-10mg IV bolus
 Short onset/Intermediate durationShort onset/Intermediate duration
 Used for one time/short-term paralysis or repeatedUsed for one time/short-term paralysis or repeated
boluses as needed for longer duration of paralysisboluses as needed for longer duration of paralysis
 Caution in liver and neuromuscular diseaseCaution in liver and neuromuscular disease

37. ParalyticsParalytics
 Continuous infusion:Continuous infusion:
 Cisatracurium (Cisatracurium (NimbexNimbex))
 Loading dose: 0.1-0.2mg/kg IV bolusLoading dose: 0.1-0.2mg/kg IV bolus
 Maintenance dose: 2.5-3 mcg/kg/min continuousMaintenance dose: 2.5-3 mcg/kg/min continuous
infusioninfusion
 Titrate infusion to 2/4 on “Train of Four” (TOF)Titrate infusion to 2/4 on “Train of Four” (TOF)
 Intermediate onset/intermediate durationIntermediate onset/intermediate duration
 Safe to use renal and liver failureSafe to use renal and liver failure