Convention Modes of Mechanical VentilationPurwokoSMF Anestesiologi & Terapi IntensifRSUD Dr. Moewardi

*PRESSURETIMEInspirasiEkspirasiPLATEAU PRESSUREPEAK PRESSURE0KURVA NAFAS SPONTAN DAN VENTILASI MEKANIK

Respiratory FailureTipe 1: gagal nafas oksigenasi : Lung failureTipe 2: gagal nafas ventilasi : Pump failureKombinasi tipe 1 dan 2PaO2 < 60 mmHgdengan FiO2 60%PaCo2> 50 55 mmHgKecuali : alkalosis metabolik terkompensasiPPOKShunting intrakardiak Aklimatisasi High altitude

Penanggulangan gagal nafasGagal nafas mengancam, Gagal nafas akut, Gagal nafas mengancam nyawa? Terapi oksigen : kanul, simple-mask, rbm, non-rbm ventimaskKausal (?) : antidotumNIPPVIPPV

IPPV Terapi supportif (airway-pressure therapy) Udara masuk karena ada perbedaaan tekanan Diberikan sejumlah volumeTekananAda hubungan antara tekanan dan volume P-V relationship : static mechanicsAda hubungan antara tekanan dan flow :dynamic mechanics

IPPV beberapa mode of ventilation Conventional (primary) modes Dual control modes Biphasic pressure modes

Prinsip Kerja Ventilator (umum)Pneumatik/ mekanikSumber gas : Oksigen dan compressed airKatub inspirasi, katub ekspirasi, sirkuit ventilatorElektronik/ mikroprosesorSistem kontrol, panel kontrol, monitor dan alarmSistem untuk sinkronisasi ventilator - pasien

Sumber Gas VentilatorSuplai Sentral atau LokalOksigen (penuh 130 atm, 1990 2200 psi)Udara tekan (compression air)Oxygen Air mix (Blender) mengatur FiO2Reducing valve outlet 45 55 psiWorking pressure 40 60 psi

Kondisi Gas InspirasiHarus cukup hangat (370 C)Harus cukup lembab Heat moisture exchanger (HME) : di Y-pieceKendala HME : dead space , resistensi , hipotermia, air leaks, Vt sangat besar, sekret >>, CO2 (k.i) Heated humidifier (di dalam jalur inspirasi)Dead space tak , Resistensi tak

Sistem KontrolModus ventilasi mekanik ditentukan oleh kontrol :Fungsi awal inspirasi (Initiation / Trigger)Akhir inspirasi (Limit / Target)Awal ekspirasi (Cycle off)

Initiation / TriggerControl breath machine triggered (time based)Assisted breath patient triggered Pressure trigger (-2 cmH2O)Flow trigger (fixed, adjusted, flow by)Cegah : *self cycling auto triggering*respons delay

Limit / TargetDipakai untuk memberi nama ModeTarget volume Volume controlTarget tekanan Pressure control

Target volume awasi pressureTarget pressure awasi volume

Faktor yang mempengaruhi target : resistesi tube, jalan nafas, compliance, aktifitas muskular, PEEPi

Cycle offTarget ditentukan oleh : volume (tidal volume) dan pressure (airway pressure)Cycle off ditentukan oleh :Elapse timeInspiratory flow rateTarget dan cycle off dapat saling terkait

Cycle offTime-based cyclingDipakai pada : controlled atau assist controlSetting Ti:*langsung (sekian detik)*berdasar kombinasi f dan I:R ratio*berdasar peak flow rate dan volume tidalFlow-based cyclingDipakai pad: assist-spontaneous, fully spontaneousExpiratory trigger sensitivity : nilai absolut, 25% dari peak flow rate, dapat diatur

Conventional mode of mechanical ventilationVCV: Volume Control VentilationVAV: Volume Assist VentilationVACV: Volume Assist-Controlled VentilationIMV: Intermittent Mandatory VentilationSIMV: Synchronized IMVPSV: Pressure Support VentilationPCV: Pressure Controlled Ventilation

VCV: Volume Controlled VentilationVentilator memberikan nafas sesuai preset rate dan preset volume tidal Tidak boleh ada nafas spontanHanya pada pasien tanpa usaha nafasKeuntungan : Otot pernafasan istirahatKerugian :Tidak ada interaksi ventilator pasienPerlu sedasi dan/ atau pelemas ototPotensial mengganggu hemodinamik

VAV: Volume Assisted Ventilation Volume cycled (presed vol tidal) Vt diberikan sesuai preset rateVentilator dpt meningkatkan nafas bila usaha nafas pasien meningkatKeuntungan : Pasien menentukan bantuan ventilasi Kerja nafas menurunKerugian : Gangguan hemodinamik, hiperventilasi

SIMV : Synchronized Intermittent Mandatory VentilationMode untuk proses weaning (pasca bedah dll)Mulai dengan 10x, diturunkan bertahapVolume cycled (preset Vt) dan preset rateNafas spontan bolehVenttor memberi nafas sinkron dg awal inspirasiBisa digabung dengan pressure supportKeuntungan : interaksi vent pasien >Efek pada hemodinamik nyaman, interaksi pasien vent baik, kerja nafas menurun.Kerugian: back up hanya alarm apnea, toleransi psn bervariasi

PCV: Pressure Controlled Ventilation,IRV: Inverse Ratio VentilationMachine triggered, preset pressure, time cycledControlled atau Assisted bergantung effortPIP (Peak Inspiratory Pressure) dibatasiSetting tepat flow rate, Ti dan mean-Paw IVR (1:1 atau 2:1) untuk inflasi alveolar, rekruitmen dan oksigenasiPerlu sedasi atau pelemas ototHati2 auto-PEEP atau PEEPiOpen Lung Concept pada ARDS

CPAP: Continuous Positive Airway PressureMode untuk proses weaning (sebelum T-piece)Bukan mode asliNafas spontanTekanan base line tinggiRate dan Vt bergantung pada usaha nafas pasien

PEEPDapat dipasang pada semua mode of ventilation FRC meningkatMencegah kolaps alveoli yang patent(10cmH2O)Pada edema paruMendistribusi extravascular lung waterMemperbaiki FRCLung compliance, difusi oksigen

Aplikasi PEEPMulai 5cmH2O ditingkatkan 2 3cmH2OPantau tanda vital, PaO2Efek samping Barotrauma Hipotensi Penurunan curah jantung Peningkatan dead space alveolar Perburukan oksigenasi

Pedoman Memulai Ventilasi MekanikPilih mode paling familiarFiO2 mulai 100% turun bertahap, SpO2 > 92%Vt awal 8 10 cc /kgBBRR dan MV sesuai kebutuhan klinik I/E 1:2PEEP (mengurangi FiO2, membantu oksigenasi mis: pada edema paru diffus)Hindari tek inspirasi terlalu tinggi (kurangi flow rate atau volume tidal)Hb, curah jantung, sat. oksige darah arteriSedasi, analgesi, perubahan posisiBila hipotensi, ingat tension pneumotorak

Sasaran Ventilasi MekanikOksigenasi :FiO2 awal tinggi bukan masalahPertahankan saturasi O2 > 92%Peran PEEPVentilasi :Sesuaikan dengan kebutuhan klinikNilai pH dan PaCO2 bersama-samaPerlu hipo/ hiperventilasi pada keadaan khusus : Acidemia, hiperkapnia kronik

Ventilator Induced Lung InjuryPotential to Produce or Augment Injury High Peak Inflation Pressures Alveolar Overdistention Shear Forces Alveolar Recruitment/ DerecruitmentPEEP has Beneficial RoleCorrect Ventilator Management Strategy Favorably Impacts Outcome

BiotraumaVentilatory strategies with high tidal volumes and low PEEP can lead to bacterial translocation from the lung into the systemic circulation Nahum A, et al.Crit Care Med 1997; 25: 1773-1743 Verbugge SJ, et al.Intensive Care Med 1998; 24: 172-177High tidal volume low PEEP ventilation has been shown to increase cytokines in BAL fluid and in the systemic circulation Ranieri VM, et al.JAMA 1998. 282: 54-61

Lung Protective Strategies by PflexKeep PEEP above llower Pflex to avoid alveolar underrecruitment Keep tidal breathing between upper and lower Pflex to avoid alveolar overdistension

Ventilatory Strategy for ARDSPplt > 35 cmH2O or High FiO2 with SaO2 < 90%PC 1:1 Higher PEEP & Lower VTSedation & ParalysisSaO2 < 90%Pplt > 35 cmH2OSaO2 > 90%Pplt > 35 cmH2OSaO2 < 90%Pplt < 35 cmH2OPCIRVPermissive HypercapniaPEEP

Jenis Pernapasan Kendali

Breath TypeInitation (Tigger)Limit (Target)Cycle-offMandatoryMesinMesinMesinAssistedPasienMesinMesinSupportedPasienMesinPasienSpontaneousPasienPasienPasien

Aplikasi Fungsi Pernafasan dengan Ventilator

FungsiModeParameter primerKeteranganInitationControlInterval waktuTrigger: mesinAssistAmbang tek (-) jalan nafasTrigger: mesinLimitVolumePreset volume tidalVariasi tek jln nafasPressureTekanan jalan nafas tercapaiVariasi volume tidalCycle-offVolumeVolume preset tercapaiPressureTekanan preset tercapai TimeInterval waktu terlewatiIns. Pause (aliran nol)FlowMenurun sp laju aliran minimalPola aliran inspirasi

PenutupMode apapun yang dipakai, VM hanyalah bantuan fisiologik, bersifat sementaraPerbaikan terhadap penyebab gangguan tersebut merupakan tujuan utamaHendaknya selalu diingat efek samping yang tidak diinginkanDalam memenuhi oksigenasi tidak hanya ventilasi tetapi perfusi juga berperan sangat pentingGunakan ventilator yang paling familiarMech. Ventilation is still more art than science

Lesson from Protective Ventilation StrategyPEEP to open the alveoliLow VT to prevent over distentionPplat < 30 cm H2OHigher respiratory rate to overcome acidosis permissive hypercapneaFrequent recruitmentAPRV

APRVIs similar to CPAP in that the pt. is allowed to breathe spontaneously without restrictionCombines two separate levels of CPAP and the pt. may breathe spont. From both levelsPeriodically, pressure is dropped to the lower level, reducing mean airway pressureDuring spont, expir. the CPAP is dropped (released) to a lower level which simulates an effective axhalation and CO2 removal

Problem with Older ModesMore work of breathingLess patient comfortEither Volume or Pressure is not assuredless securityNeed more frequent adjusment

Volume Assured Pressure Support (VAPS)Parameters set :Pressure limit = plateau pres. seen during VCRespiratory ratePeak flow ratePEEPFiO2 Trigger sensitivityMinimum tidal volume

Volume Assured Pressure Support (VAPS)Amato et al. Chest 1992; 102: 1225 1234 VAPS vs ACLower WOBLower RawLess PEEPi

Pressure Regulated Volume ControlPressure limitedTime cycledAdaptive pressure ventilation (Galileo)Autoflow (Evita 4)Automatically adjust pressure support level to minimum needed to maintain constant set TV

AutomodeSiemens Servo 300ACombines volume Support and PRVC into a single modeSwitches between PS and PC, with pt effort determining whether the breath will be VS or PRVC

AutomodeIf pt makes no effort, you get PRVCAs pt begins to breathe spontaneously, switch to VSMean airway pressure could become too lowNo evidence to advocate its use

Adaptive Support VentilationHamilton GalileoDual control, breath to breath modePressure limit of spontaneous and mandatory breaths is constantly adjustedBased on idea that a pt will breathe a TV and rate that minimizes elastic and resistive loads

Adaptive Support VentilationParameters set: Ideal BW High pressure alarm PEEP FiO2Flow cycle variable (10 40%) of initial peak flow, and % volume control (20 200%)Ventilator delivers as volume control 100 ml/kg/min for adults 200 ml/kg/min for childres

Adaptive Support VentilationIf pt makes no effort to breathe, ventilator delivers required minute ventilation as PCIf pt starts to breathe spontaneously, ventilator gradually reduces number of mandatory breaths and lower pressure support level as necessary to keep minute ventilation above the minimum setting

Adaptive Support VentilationIf pt spontaneous TV is more than the target and rate is less, the pressure limit is reduced and rate of mandatory breaths is increasedIf TV > target and rate > target, pressure limit is lowered and number of mandatory breaths is reduced

Adaptive Support VentilationPotential Advantages matches ventilation to lung condition quicker, automatic weaning decreased risk of lung damagePotential Disadvantages leaks my defeat algorithmoperator must select appropriate % of minute ventilation to support deadspace may cause problems

Automatic Tube CompensationDrager Evita 4Overcome WOB added by artificial airwaysImproved patient/ ventilator synchrony by providing variable fast inspiratory flow

Automatic Tube CompensationDue to varying inspiratory flow rates, no single level of pressure support can actually fully compensate for WOB caused by ETTAutotube uses known static resistence for each size and type of ETT/ tracheal tube, and measures flow rates

Automatic Tube CompensationPressure is applied and continuously adjusted proportional to resistanceTracheal pressure (cm H2O) = proximal airway pressure (cm H2O) tube coefficient (cm H2O/L/sec) x flow2 (L/min)

Automatic Tube CompensationPotential Advantages simulates breathing without tube decreases patient work of breathingPotential Disadvantages actual tube resistance may changesecretions, kinkingMay not simulate actual conditions- swelling after extubation

Proportional Assist VentilationThe goal is to maintain a constant fraction of work per breath done by ventilatorIf ventilator is set to give 80% volume and flow assist, if the tidal volume increases, the pressure increases to keep the amount of patient work constant

Proportional Assist VentilationPotential Advantages support matched to need-Only abnormal load is supported better machine patient synchronyTheoretically the best mode Potential Disadvantages leaks defeat ventilator algorithm no ventilation if patient stops breathing

ConclusionModern ventilators offer several potentially very useful new modes designed for variety of purposesMost of newer modes offer the benefits of pressure-limited breaths with the security of an assured minimum tidal volumeMore patient comfort with less patient work

Mechanical VentilationMechanical Ventilation physiologically supportive notEthiologically curativeOther TherapyFunctional Autonomy re-establishedTherapyGoalTimeStrategyPrimum non nocere