VIMA (Volatile Induction and Maintenance Anesthesia) How and Why James H. Philip M.E.(E), M.D. © Copyright 1995 - 2009, James H Philip, all rights reserved
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VIMA(Volatile Induction and Maintenance Anesthesia)
How and Why
James H. Philip M.E.(E), M.D.
© Copyright 1995 - 2009, James H Philip, all rights reserved
VIMA(Volatile Induction and Maintenance Anesthesia)
How and Why
James H. Philip, M.E.(E.), M.D.Anesthesiologist and
Director of Bioengineering,Brigham and Women's Hospital
Associate Professor of Anaesthesia, Harvard Medical School
Medical Liaison, Partners Biomedical Engineering
Gas Man
Info:gasmanweb.com
I will u
se
Three unique uses for Sevoflurane
Almost uniqueSevoflurane SedationSevoflurane for a difficult airwaySevoflurane Vital Capacity Induction
Sevoflurane Sedation
2 L/min FGFSevoflurane 2%PO Oral Ibuprofen (Advil, Motrin) $0.50
It worksNo need for other drugs
IV Induction agent (Pent/Prop)OpioidMuscle relaxant (any NMB)Reversal agents for NMB
Why do VCI?
VIMA reference
Philip BK, Lombard LL, Roaf EF, Drager LR, Calalang I, Philip JH. Sevoflurane vital capacity induction compared with Propofol intravenous induction for adult ambulatory anesthesia. ASA 97, San Diego CA. Anesthesiology V87:A3, 1997. A&A August 1999
No relaxants No Propofol
No relaxants No Propofol
No use
No relaxants No Propofol
No use
No waste
InexpensiveSatisfying toPatientAnesthesiologistSurgeon
Why do VIMA?
Howto do
VolatileInduction
Premedication
None, typicallyAnything, as requiredTry talking, first
Sedation possibility
Propofol 10 mgBWH Pharmacy makes 10 mL syringes2 mL syringes would be better
Volatile Induction
Fast*Volatile agent with nitrous oxide, aloneDeep breath
51 ± 4 seconds, 1 - 4 breaths39 ± 3 seconds, if 1 breath
* Philip BK, Lombard L, Calalang I, Philip J. Sevoflurane Vital Capacity Induction Compared with Propofol Intravenous Induction for AdultAmbulatory Anesthesia. Anesth & Analg 87:623-7, 1999.
Sevo + Nitrous Oxide
1) Like we published2) Later I will describe without Nitrous Oxide3) Later I will describe a “no prime” method
2 minute Preparation
Volatile Prime for anesthesia circuit
Oxygen Prime for lungs
Mental Prime for patient
Volatile Prime GoalPrime the circuit with8% Sevoflurane66 - 75% N2O
Semi-Closed CircuitVolatile Prime8% Sevoflurane1 L / min O2
3 L / min N2OPrime for 2 minutesSame time as pre-oxygenation
Volatile PrimeRequired to provide
sudden, large, controlledincrease ininspired anesthetic concentration
Inspired Control by any means is OKNew machines and techniquesmay make this easier
How to do Volatile Prime
Volatile PrimeFGF = 0 - flows all offEmpty the circuit by squeezing bagOpen relief (APL, pop-off) valve partlyAttach maskSeal mask
Glove, stopper, cork, plug, other
One way - seal mask with glove
Another way -seal mask and circuit with tight-
fitting occluder
Prime the CircuitSet VaporizerSet FGFLet Reservoir Bag fill
When Bag is full, empty it through APLFill Bag second timeFill bag third time
Why three Bag fills?
Normal flow in breathing circuitNormal use, not Circuit PrimeFlow goes forwardIn the direction of the valvesEmptying and filling reservoir bagand lungs,alternately
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Normal flow in the breathing circuit - Inspiration
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Normal flow in the breathing circuit - Expiration
Priming the Circuit
Flow goes backwardsBlocked by each valveFilling the reservoir
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Back-fill the breathing circuit (#1)
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Back-fill the breathing circuit (#1)
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Back-fill the breathing circuit (#1)
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty the reservoir bag (#1)
Squeeze
CO2
Ab-sorb-ant
Sampled
Exhaust
200 mL/min
Fresh
Fill the reservoir bag again (#2)
CO2
Ab-sorb-ant
Sampled
Exhaust
200 mL/min
Fresh
Empty the reservoir bag (#2)
CO2
Ab-sorb-ant
Sampled
Exhaust
200 mL/min
Fresh
Fill the reservoir bag again (#3)
CO2
Ab-sorb-ant
Sampled
Exhaust
200 mL/min
Fresh
Close the Exhaust Valve
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty reservoir bag (#3) and fill the inspired limb
Squeeze
Closed
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty reservoir bag (#3) and fill the inspired limb
Squeeze
ExhaustClosed
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty reservoir bag (#3) and fill the inspired limb
Squeeze
ExhaustClosed
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty reservoir bag (#3) and fill the inspired limb
Squeeze
ExhaustClosed
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Empty reservoir bag (#3) and fill the inspired limb
Squeeze
ExhaustClosed
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Open the Exhaust - Fill the Expired Limb (#3)
Release
Sampled
CO2
Ab-sorb-ant
200 mL/min
Fresh
Open the Exhaust - Fill the Expired Limb (#3)
Release
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Remove Glove, Apply mask to patient (#4)
Release
Patient
Gas Monitor shows Circuit is Ready
Circuit is ready
Gas Monitor shows Circuit is Ready
Circuit is ready
After third bag-fill
Here is how to test when ckt is ready
Sampleto gas monitor
Sample from Reservoir Bag Attachment
Bag #
2 minute Preparation
Volatile Prime for anesthesia circuit √
Oxygen Prime for lungs
Mental Prime for patient
While priming circuitPreoxygenate
Simple Circuit
Simple parts
Simple parts
Reservoir bag(with cut end)
15-22mm adapter
Sampling(oxygenating)
Elbow
Oxygensource
Mask
Option in some countries:SiBI* Connector
*Single Breath Induction Connector
Facilitates pre-oxygenation during circuit prime
Breathing Circuit Problems
Airway Agent and CO2 (most)
Agent
CO2
Exp Exp InspInsptime
Sampled
Exhaust
CO2
Ab-sorb-ant
200 mL/min
Fresh
Exhaled and Fresh Gas mix during inhalation
Inspired = perfect mix of Fresh and Absorber gas
GE ADU
Unique CO2 Absorber AssemblyFGF enters downstream of Inspiratory valveInspiratory concentration has two phases
Fresh GasAbsorber GasThese two do not mix; they arrive in sequence
Inspired peak concentration is very highInspired mean concentration is much lower
CO2
Ab-sorb-ant
ADU
GE “ADU” FGF path
I,E
Airway Agent and CO2 (ADU)
Agent
CO2Insp Insp
ExpExp
Peak Inspired Agent MonitoringSome monitors report Inspired = Peak InspiredThis is a problem if Mean and Peak differMean is representative of what affects uptakeGE-Datex-Ohmeda monitors now report Mean InspiredThis makes them work with all circuits including ADUOther brand monitors usually report Peak InspiredThese report incorrect inspired concentrationNext slide shows example
2 minute Preparation
Volatile Prime for anesthesia circuit √
Oxygen Prime for lungs √
Mental Prime for patient
Mental Prime PatientInstruct and practice VCVC = Vital Capacity breath
Breathe all the way out Take a deep breath inHold it inMaintain positive verbal contact
Create positive experiencethrough words and actions
2 minute Preparation is done
Volatile Prime for anesthesia circuit √
Oxygen Prime for lungs √
Mental Prime for patient √
Ready for Volatile Induction
VI - Volatile InductionSay and DoSay: “Exhale”Do: Switch to Sevoflurane maskSay: “Inhale and hold inspiration”Do: Maintain positive verbal contact Maintain high (7%) inspired sevoflurane conc.
> One Breath Induction
If patient breathes outInstruct patient to
take another deep breath and hold itTake another deep breath and hold itTake another deep breath and hold it
Data from BWH First Series
18 patients with perfect data for analysisIn first 20 seconds after VCISevoflurane %M SD
Inspired = 6.2 + 0.8Expired = 4.2 + 0.8
Nitrous OxideMean = 58 + 6
Most lost lash reflex in 1 breathSome required 2 breathsFew required 3 breaths
J Philip current technique
Sevoflurane in Oxygen, no Nitrous OxideNo need to pre-oxygenateOxygenation and Anesthetization together
Anesthetize and Oxygenate togetherVCI Sevo 8% in Oxygen
Slightly slowerNo Second Gas EffectNo additional effect of N2O
Always quite adequate
Impact of N2O on VCI
GE Aisys requires no circuit prime
Inspired = 8 % first big breath
Inspired = 8 % first big breath
Inspired is maintained at 8 %
Graphic Trend - Agent & MAC
Volatile Induction Phase TwoDeepen Inhalation Anesthesia
Applies to all the techniques above
Volatile Induction Phase TwoDeepen Inhalation Anesthesia
After loss of consciousness in 1 minContinue induction with 8% SevoAssist or control ventilationPrepare to secure airway if desired
O2 + SevoSecure airway
LMA OK in 2 minutes ETT OK in 3 - 5 minutes (no relaxant)
Produce apnea before removing mask
Hyperventilate to apnea
Avoid losing anesthetic fromlungsbloodbrain
Extends intubation window (2 MAC to 1 MAC)from 3.5 minutes to 12 minutes
Or, keep anesthesia light
Natural airway orMinor airway interventions
Oropharyngeal airwayNasopharyngeal airway
Deepen anesthesia before incision
Monitor
CarefullyOftenBP q 1 minute (for a while)Always “automatic”
Induction is complete
Maintenance begins
Get Sevo level down to 1 MAC
Usually requiresHigh FGFVaporizer OffExpired falls to < 1 MACVaporizer on (3%)FGF = 4 LPM while vaporizer is off
VM - Volatile Maintenance Anesthesia
We have always done thisMaintain desired anesthetic depthDecrease fresh gas flows to save costIncrease vaporizer settingMaintain previous expired anesthetic conc.Maintain previous anesthetic depthIncrease and decrease depth as requiredReact or anticipate
VM - Volatile Maintenance Anesthesia
Depth = Constant + Adjust as requiredThree anesthetic conditions
Constant IncreaseDecrease
VM - Volatile Maintenance Anesthesia
Depth = Constant + Adjust as requiredThree anesthetic conditions
Constant Increase Vaporizer to Max = 8%Decrease Vaporizer off = 0%Increase FGF if required
Readjust vaporizer to near prior setting
Overpressure
Underpressure
Up and downusing Overpressureand Underpressure
2
4
6
8
10
0-10 -20 -30
time (minutes)
I
E
For short cases, remember
Awakening begins just after inductionDon’t be afraid to turn the vaporizer offBring expired concentration down to 1.3 MACKeep expired at 0.7 MAC near the very end
Prepare for recovery - always
Recovery begins with wake upRecovery ends with
patient back to normalNormal means normal -
Patient is satisfiedAnesthesiologist is satisfied Surgeon is satisfied
Volatile EmergenceVolatile emergence is smooth
Create and maintain zero (0.0) inspired agent concentrationEmpty the Reservoir Bag, Flush O2, High FGF
Ventilate anesthetic out of lungsMinute ventilation > 4 L/minpETCO2 around 36 mmHg
FGF is low
Increase FGF
Problems occur with wake up if FGF or Ventilation is low
Poor circuitwash out;FGF too low
Ventilation is lowProblems occur with wake up if FGF or Ventilation is low
Poor lung wash out.Ventilation is too low
Better wake up w experience
Usually, wake up is better
Low inspiredLow expired
No need forIV Induction agentOpioidMuscle relaxant (NMB)Reversal agents for NMBOther drugsComplications
Avoid Side EffectsAvoid Costs
Clinical Benefits of VIMA
VIMA providesDeep anesthesia from beginning to endNo additional drugs for intubationNo additional drugs for intra-op painRapid awakening and return to normalPost-op pain requires local anesthesia infiltration
anesthesia and post-op analgesic
How toavoid slow wake ups
FGF is low
Increase FGF
Problems occur with wake up if FGF or Ventilation is low
Poor circuitwash out;FGF too low
Ventilation is lowProblems occur with wake up if FGF or Ventilation is low
Poor lung wash out.Ventilation is too low
Better wake up w experience
Usually, wake up is better
Better wake up w experience
Usually, wake up is better
Low inspiredLow expired
With Draeger Anesthesia Machines
Empty Reservoir Bag to WAG systemWatch Inspired Agent and assure zeroPress and hold Oxygen Flush Button
OK Manual, Assist, or Control (Draeger only)All this Fabius or Apollo
Show Gas Man ® Results
Gas Man® shows VIMA, start to end
AgentMonitor
GraphE
I
IE
I
E
Agent Monitor Graphwhole case
Gas Man Graph whole case
E
I
E
I
AgentMonitor
Graph
GasMan®
Graph
Superimpose
SummaryVIMA is Volatile Induction and Maintenance Anesthesia.VIMA is an acceptable equivalent alternative to IV plus Volatile combinations.VIMA preparation requires 2 minutes for circuit anesthetic prime, lung oxygen prime, and brain psychological prime.VIMA Sevoflurane induction is faster than IV Propofol (51 ± 4 sec vs. 81 ± 12 sec).VIMA w/o N2O is almost as fastVIMA wake up is as fast and uncomplicated as Propofol induction and VM anesthesia.
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