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

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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.

Thank you

Jphilip@partners.org