Tiva & tci for 1118

Total intravenous anesthesia (TIVA) & Target Controlled Infusion(TCI)

台北榮總麻醉部王審之

TIVA

• Total intravenous anesthesia– Amnesia and analgesia

• Sedation in intensive care unit• Day surgery• Office based anesthesia

– Muscle relaxant

What is TCI ?

TCI

• Target controlled infusion– Amnesia: propofol

• Infusion model: Marsh, Schnider

– Analgesia: opioid• Fentanyl• Alfentanil• Remifentanil• Sufentanil

Time (min)

Alfentanil effect site concentration in endoscopic submucosa dissection petients

TCI for adult: propofol

Infusion mode for Propofol

• Marsh– Derived from Gept’s model (1987)

• Regional anesthesia combined propofol infusion• Total 18 patients• No BMI data

– Scarecely adequate in the elderly• Anaesthesia 1998;53:Suppl. 1:61-67• Ann Fr Anesthn Reanim 2000;19:R027• For patients less than 70y/o

Infusion mode for Propofol

• Modified Marsh– Anesthesiology 2000;92:399-406– 20 women (health volunteers), age: 18-60y/o

• Obesity is excluded• Target concentration 5.4μg/ml

– A biophase model combining the Marsh kinetics and a time to peak effect of 1.6 min accurately predicted the time course of propofol drug effect.

Infusion mode for Propofol

• Schnider– Anesthesiology 1998; 88: 1170-1182– Patient population: 25-81y/o health volunteers

• Patient number: 24• Body weight: 44.4~123 kg

– Covariates• Age, gender, height and body weight, lean body mass• BMI: <43 (M) and <35(F)

lower keo demand a higher concentration gradient between plasma andeffect-site to achieve a certain effect-site target concentration,

Which is better

• In a recent clinical trial, changes in the BIS correlated better with effect site concentration predictions by the original Marsh model than with the Schnider model.

– Anesthesia 2007; 62: 661-6

• Potential benefits with the Marsh II and Schnider models are reduced hemodynamic and respiratory effects.

– Age is included as a pharmacokinetic co-factor in the Schnider model

TCI for adult: opioid

Fentanyl

Context sensitive half time: The time required for the drug concentration to decrease to half of it’s value.

Fentanyl recipe

• Bolus 3 μg/kg over 30sec• Followed by 2 μg/kg/hr for 30min• 1.5 μg/kg/hr from 31-150min• 1 μg/kg/hr until 30min before skin closure

Alfentanil

• The model of Scott– J Pharm Experiment Ther 1987; 240: 159-166– More accurate than the model of Maitre

• Anesthesiology 1990;73:66-72• Anesth Analg 1993;77:801-810

– Clearance mainly dependent on liver metabolism• Enzyme inhibitor: cimetidine, fluconazole, diltiazem, macrolide (erythromycine),

imidazole

Hypnotic combined opioid

Alfentanil

TCI diy

TIVA trainer for simulation

• Download from EuroSIVA website

– 100 Euro for registration

Should we routinely monitor anesthetic depth in TIVA?

Propofol infusion syndrome

• Defined as acute bradycardia progressing to asystole combined with lipemic plasma, fatty liver enlargement, metabolic acidosis with negative base excess > 10mmol/l, rhabdomyolysis or myoglobinuria associated with propofol infusion.– Large dose, prolonged duration.

• A hereditary mitochondrial fatty acid metabolism impairment resembling medium chain acyl-CoA dehydrogenase deficiency is responsible for the susceptibility to the development of propofol infusion syndrome.

• Minerva anestesiol 2009;75:339

TCI without monitoring

• Driving with one eye closed.– Expert opinion

AEP guided propofol infusion

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5

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3

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800700

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BIS

• Processed EEG– 40-60: general anesthesia– >90 awake, memory intact

• Limitations – Not useful during Ketamine anesthesia– Insufficient information on effects of N2O, high-dose opioid &

neurologic disease.– False-elevated BIS

• EMG activity• High electrode impedances

– Does not predict the moment consciousness returns

NEJM 2008

• No difference in awareness.• Not associated with reduced administration of volatile

anesthetic gases.• Awareness occurred even when BIS values were within the

target ranges.

AEP

• Not significantly affected by opioids.• Auditory modality is the most receptive sensory channel for

perception during anesthesia.• Limitations

– False elevated AEP• EMG activity

– BIS and AAI markedly decreased after administration of myorelaxant . A&A 2008; 107(4): 1290-4

• Noise ??

BIS vs AEP

• The range of values obtained at the time of loss of eyelash reflex AEP: 15-99 BIS: 39-83

BIS vs AEP

• The awake values for AAI were less and showed more variation between subjects than BIS.

Closed loop system

• The input– Drug delivery (etc. propofol, opioids)

• The output– evoked potential, bispected index (BIS), blood pressure, pulse rate.

Discussion …

• Can anesthetic depth monitoring decrease unnecessary propofol use?– Putative early propofol infusion syndrome: typical symptoms without

cardiac involvement.• Monitor pH, lactate, base excess and creatinine kinase is recommended.

Can we applied propofol continuous infusion for children or even infant ?

Infusion mode for Propofol

• Kataria– Anesthesiology 1994; 80: 104-122– Patient population: 3-11y/o children receiving body surface surgery.

• Patient number: 53

– Three-compartment pharmacokinetic model• Weight-adjusting the volumes and clearances significantly improved the accuracy.

Infusion mode for Propofol

• Marsh (Pediatric)– BJA 1991; 67: 41-48

• Marsh (Pediatric)

– Patient population: 1-12y/o children receiving minor surgery• Patient number: 20

Infusion mode for Propofol

• Paedfusor – BJA 2003; 91: 507~513– 32 children of ASA status II±III, undergoing elective cardiac surgery or

cardiac catheterization were enrolled.– The effect of bypass

• system was negative during bypass: -5.5%• Large volume of distribution (ml): 270: 4600: 1340: 8200

– No outcome data

For pediatric anesthesia

• Propofol is not indicated for use in children < 3y/o.– Pediatric Anesthesia 2004; 14: 374-379– Still lack of FDA approval

• Propofol is not approved for sedation in pediatric ICU patients.

• Minerva anestesiol 2009;75:339

For MEP monitoring

• J Neurosurg Pediatrics 7:000–000, 2011– From Texas– For 10 children age under 3 year old (mean age: 16.8 months)

receiving complex spine surgery– Sevo induction– Maintenance: propofol 6-15mg/kg/hr– No mention of OP time

• Discussion: The loss or absence of MEP amplitude may be minimized when propofol is administered in small, titrated doses (6-15mg/kg/hr) in a child younger than 3 years of age.

In PICU in Australia and NZ

• The majority of practitioners (82%) use propofol infusion in children in PICU– the main indication being for short-term sedation in children requiring

procedures.

• 67% of paediatric intensivists use maximum infusion doses that may be considered dangerously high (> or = 10 mg/kg/h)

• 19% use propofol infusion for prolonged periods (> 72 hours). • A smaller proportion (15%) of respondents indicate that they

may use both higher doses and prolonged periods of infusion• Anaesth Intensive Care. 2002 Dec;30(6):786-93.

For prolonged sedation

• Propofol should be used with extreme caution for prolonged sedation in intensive care unit patients, at dose rates of below 5 mg/kg per h

• Curr Opin Anaesthesiol. 2003 Jun;16(3):285-90

• TIVA with propofol in infants younger than 1 year old requires extensive experience with TIVA in older children and with the handling of this special age group and should be undertaken with maximum precautionary measures.– Infusion rate up to 9mg/kg/hr over 2-4hours are recommended for

TIVA in children.• Anaesthesist. 2003 Sep;52(9):763-77.

BIS for children

• The Bispectral Index correlates well with the Ramsay score in the normal sedated child. • Pediatric Critical Care Medicine: January 2003 ; 4(1) 60-64

Can patient outcome be determined by anesthetic agent we used?

TIVA in cardiac surgery

• Still no conclusion– 30-day mortality in acute procedure was significantly lower in the

propofol group.– 30-day mortality caused by infection, pulmonary causes or renal

causes was significantly lower in the propofol group.– J Cardiothorac Vasc Anesth 2007;21:664-71

– Volatile anesthetic in AVR: better preservation of myocardial function and a reduced postoperative release of troponin I.

– Less ICU stay in the volatile anesthetic group.– Anesth Analg 2006;103:289-96

Safety issues for office-based anesthesia

2008 ASA statement

• A reliable source of oxygen and backup oxygen sources.• An adequate and reliable source of suction. • Reliable system for scavenging waste anesthetic gases.

– while inhalation anesthetics are administered…

• Adequate illumination of the patient, anesthesia machine and monitoring equipment. – Hard to define adequate illumination.

• Sufficient space to accommodate necessary equipment and personnel.– Most critical part in most circumstances in our hospital.

• Sufficient electrical outlets

2008 ASA statement

• Anesthetic equipment– a self-inflating hand resuscitator bag capable of administering at least

90 percent oxygen as a means to deliver positive pressure ventilation– adequate anesthesia drugs, supplies and equipment for the intended

anesthesia care– adequate monitoring equipment

• An emergency cart– a defibrillator– emergency drugs– equipment adequate to provide cardiopulmonary resuscitation

• adequate staff trained to support the anesthesiologist and a reliable means of two-way communication to request assistance.

2008 ASA statement

• Appropriate postanesthesia management should be provided.– Our weak point.

Statement on safe use of propofol

• ASA 2009 statement– The practitioner should be present throughout the procedure and be

completely dedicated to that task.– manage the potential medical complications of sedation/anesthesia. – proficient in airway management– have advanced life support – understand the pharmacology of the drugs used.– Monitoring

• Ventilation: Monitoring for the presence of exhaled carbon dioxide should be utilized because movement of the chest will not dependably identify airway obstruction or apnea.

• oxygen saturation• heart rate • blood pressure.

Summary

• Safer environment– Oxygen supply and suction should be close to the patient.

• Safer equipment– Emergency cart: defibrillator– Keep ABC in mind – End-tidal CO2 monitoring

Thanks for your attention