CORCIONE A.

D'ANDREA, FRANCESCO

FERRARO G.

Archivio della ricerca - Università degli studi di Napoli Federico II

Total Intravenous Anesthesia/Target-Controlled Infusion and Auditory-EvokedPotentials in Day Surgery MammoplastyG. A. Ferraro, M.D.,1 A. Corcione, M.D.,2 and F. DAndrea, M.D.11Department of Plastic and Reconstructive Surgery, Second University of Naples, Via De Crecchio 3, 80100 Naples, Italy2Anaesthesia and intensive care unit, A. O. Monaldi, L. Bianchi Street, 80131 Naples, ItalyAbstract. Total intravenous anesthesia and the newparameter for administering the most recent drugs, target-controlled infusion, as well as the introduction of new shorthalf-life molecules that do not accumulate have madeanesthesia in day surgery safer. In this study, the use ofauditory-evoked potentials monitoring made it possible todetermine the target plasma concentration of propofol thatinduces a narcosis suﬃciently deep and strictly necessaryfor eﬀectiveness, thus minimizing the anesthesiologic risklinked to the use and the dosing of the drug, reducing thehospitalization time, and decreasing the side eﬀects forpatients undergoing day surgery mammoplasty.Key words: Auditory evoked potentials—Day surgery—Mammoplasty—Plastic surgery—Target controlled infusion—Total intravenous anesthesiaTotal intravenous anesthesia has been used success-fully in many surgical branches because of the re-cently introduced new short half-life molecules withno accumulation eﬀects [7]. Furthermore, the newparameters for administration of the most recentdrugs, target-controlled infusion, have made daysurgery operations with the patient under anesthesiasafer [2,5,8].The aim of this study was to verify, throughmonitoring of auditory-evoked potentials (AEP)[4,5], the propofol plasma concentration targetcapable of inducing a level of narcosis suﬃcientlydeep and strictly necessary for eﬀectiveness, thusminimizing the anesthesiologic risk linked to the useand the dosing of the drug while reducing hospital-ization time and side eﬀects [4,9].Auditory-evoked potentials (AEP) use auditorystimuli to evaluate the level of cerebral activity. Theyhave been used both in studies on learning andmemory processes and in research on the evaluationof the anesthesia level.To evaluate the depth of anesthesia, midlatencyAEP (MLAEP) recorded 10 to 100 min after auditorystimulation has been primarily used because it hasshown limited intra- and interindividual variability.The AEP A-line monitor generates an index derivedfrom the analysis of MLAEP waveforms. Once thismonitor has acquired the baseline signal, thanks tosophisticated ﬁltering systems, it can extract in ashort time (only 6s) the MLAEP signal, whosechanges during anesthesia are represented by an in-dex, the A-line ARX Index (scale of 0 to 100), whichreﬂects the hypnotic state of the individual.The aim of this study was to control, by means ofthe aforementioned monitoring, the propofol plasmaconcentration suﬃcient to provoke a narcosis statusfor each individual patient, avoiding the risk ofawareness and reducing side eﬀects (caused by use-lessly high drug doses) and hospitalization time. Allthis becomes even more important in plastic cosmeticsurgery, in which day surgery and short convales-cence times are particularly signiﬁcant, because pos-tanesthesia recovery and anesthetic metabolism maybecome limiting factors.Materials and MethodsAfter written informed consent, 42 American Societyof Anesthesiology (ASA) classes 1 and 2 patientsCorrespondence to G. A. Ferraro, Via De Crecchio 3,80100, Naples, Italy; email: gaferraro@libero.itAesth. Plast. Surg. 30:538540, 2006DOI: 10.1007/s00266-004-8029-8(average age, 32 ± 4 years; average body weight,62 ± 7 kg) who had undergone augmentationmammoplasty with submuscular implantation ofmammary prosthesis (8 patients) and reductivemammoplasty due to gigantomastia of mediumgravity were studied. The average length of surgerywas 72 ± 4 min for augmentation mammoplasty and158 ± 23 min for reduction mammoplasty.Patients with allergies or intolerances to even oneof the drugs included in this study were excluded.According to the waiting list position, the patientswere divided into two groups of 21 each: group A andgroup B. The two groups were homogeneous for age,weight, ASA class, and type of operation.The following anesthesiologic protocol was usedfor all the patients: Premedication about 45 min before surgery withintramuscular (IM) atropine 0.01 mg/kg andintravenous (IV) midazolam 0.07 mg/kg Induction with a remifentanil (50 lg/ml) dose of0.25 lg/kg/min IV Maintenance with air and O2, a remifentanil(50 lg/ml) dose of 0.25 lg/kg/min IV, and cis-atracurium (boli) 0.04 mg/kg IV at 25% of trainof four (TOF). The propofol was administeredwith a target of 4 lg/ml for the group A patientsand a target of AEP values at 20 or less for thegroup B patients (Table 1).The anesthesiologic protocol is shown in Table 1. In-traoperative monitoring involved the following: sys-tolic pressure (SAP), dyastolic pressure (DAP), meanarterial pressure, electrocardiogram in derivation II (IIder.), cardiac frequency (CF), oxygen saturation, end-tidal carbon dioxide, temperature corporeal (CT),hourly diuresis. The narcosis level of the group B pa-tients was measured through the evaluation of AEP(ALARIS AEP monitor, ALARIS, Florence, Italy).Neuromuscular monitoring was performed by theTOF watch. [3,6].After the interruption of propofol administration, atthe end of the operation, the following parameterswere examined: spontaneous respiration, extubationtime, eye-opening time, performance of simple orders,time of discharge from the recovery room, and pres-ence of postoperative nausea, vomiting, shivering [1,6].Students t-test was used for statistical analysis. Allp values less than 0.05 were considered signiﬁcant.Data are expressed as means ± standard deviation.ResultsGood hemodynamic stability was achieved for all thepatients. Table 2 presents the examined parametersand Table 3. presents the side eﬀects. No episodes ofawareness were reported by the patients in the post-operative period. The plasma concentration target ofpropofol in group B was 2.4 to 2.9 lg /ml.Table 1. Anesthesiologic protocolGroup A Group BPremedication Atropina 0.01 mg/kg IMMidazolam 0.07 mg/kg IMAtropina 0.01 mg/kg IMMidazolam 0.07 mg/kg IMInduction Remifentanil (50 /ml) Remifentanil (50 /ml)0.25 lg/kg/min IV 0.25 lg/kg/min IVPropofol (target 4 lg /ml) Propofol (target 4 lg /ml)Cis-atracurium 0.20 mg/kg IV Cis-atracurium 0.20 mg/kg IVO2-Air O2-AirRemifentanil (50 lg /ml) Remifentanil (50 lg /ml)0.25 lg /kg/min IV 0.25 lg /kg/min IVCis-atracurium (boli) 0.04 mg/kg IV,at 25% of the TOFCis-atracurium (boli) 0.04 mg/kg IV,at 25% of the TOFPropofol PropofolTarget 4 lg /ml Target = value £ 20 AEPIM, intramuscular; IV, intravenous; TOF, ; AEP, auditory-evoked potentials.Table 2. Examined parametersGroup A(min)aGroup B(min)Spontaneous respiration 9 ± 2 4 ± 1Extubation 13 ± 2 6 ± 1Eye opening time 15 ± 1 7 ± 2Carrying out simple commands 16 ± 2 9 ± 1ap < 0.05.Table 3. Side effectsGroup APatients (%)Group BPatients (%)Nausea 5 (24) 2 (9)Vomiting 3 (14) 2 (9)Shivering 2 (9) 2 (9)G. A. Ferraro et al. 539ConclusionsThe monitoring of AEPs to assess the level of narcosisenabled achievement of the expected objectives: signif-icantlymore rapidawakening than in the control group,earlier discharge, and the reduction of propofol dosing,tailor made according to individual characteristics.References1. Barr G, et al.: A study of bispectral analysis andauditory-evoked potential indices during propofol-in-duced hypnosis in volunteers: The eﬀect of an episodeof wakefulness on explicit and implicit memory.Anaesthesia 56:888893, 20012. Breckenridge JL, et al.: Awareness during anaesthesia:A revue. Ann R Coll Surg 65:9396, 19833. Ghoneim M, et al.: The auditory-evoked responses andlearning and awarness during general anaesthesia, ActaAnaesthesiol Scand 44:133143, 20004. Jordan C, et al.: Monitoring-evoked potentials duringsurgery to assess the level of anaesthesia. J Med EngTechnol 19:7779, 19955. Lehmann A, et al.: Bispectral index in patients withtarget-controlled or manually-controlled infusion ofpropofol. Anesth Analg 95:639644, 20026. Loveman E, et al.: The auditory-evoked response as anawareness monitor during anaesthesia. Br J Anaesth86:513519, 20017. Padﬁeld NL: Total intravenous anesthesia. Williams &Wilkins, Baltimore, 19978. Suttner S, et al.: Cost analysis of target-controlledinfusion-based anesthesia compared with standardanesthesia regimens. Anesth Analg 88:7782, 19999. Thornton C, et al.: Evoked responses in anaesthesia.Br J Anaesth 81:771781, 1998540 TIVA/TCI and AEP in Day Surgery Mammoplasty

Total intravenous anesthesia/target-controlled infusion and auditory-evoked potentials in day surgery mammoplasty

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