Sue Pilbeam & Gopal Allada, M.D. Mechanical Ventilation Mode and Initial Settings a research-based approach RET 2264C #2 Dr. J.B. Elsberry Prof. Jean Newberry Special Thanks to: Sue Pilbeam & Gopal Allada, M.D.

Today’s Focus: Review of Basic Indications for mechanical ventilation: Type I and II Respiratory Failure and/or Protect the A/W Ventilator Modes- the basics Initiating Orders Management of the ventilated patient Review of Original Goal(s)

Who needs M.V.?

Who else needs M.V. ? Possible Goals: Improve Myocardial oxygenation Reduce intracranial pressure through controlled hyperventilation Stabilize the chest wall Protect airway 2o Neurologic impairment or airway obstruction

ABG Indications for Mechanical Ventilation ? PaO2? __________________ PaCO2?__________________ pH? ____________________

RF 2: Hypoxemia There are five reasons for hypoxemia: PIO2 is too low (i.e. high altitude, O2 supply problems) Global alveolar hypoventilation (yes it can also happen on a Ventilator!) Right-to-left shunts V/Q mismatch Incomplete diffusion

Definitions Reviewed (again) PIP: maximum pressure measured by the ventilator during inspiration (aka Pressure Limit). Pplateau static pressure (no flow) measured during inflation hold [essential for measurements of static CL ] PEEP: pressure present in the airways at the end of expiration during Mechanical Ventilation. CPAP: amount of pressure applied to the airway during all phases of the respiratory cycle (Spontaneous Ventilation). PS: amount of pressure applied to the airway during spontaneous inspiration by the patient. I-time: amount of time delegated to inspiration. I:E –(TCT/I + E ) Target VT: Tidal Volume delivered during a mechanical breath

Ventilator Orders/ Initial Set-up Protocols Ventilator Mode (let’s apply the Top Ten) f Set VT or Pressure Control (PIP & TI) FIO2 +/- PEEP . Other: inspiratory flow rate (V), flow pattern, I:E, inspiratory hold, patient trigger mode/sensitivity

M.V. -- How much Support? M.V. Modes Classified into one of following categories: those that provide full ventilatory support (machine is responsible for entire minute ventilation) those that provide partial support (pt. is responsible for some or all of the minute ventilation) Spontaneous Ventilation (pt is weaned from all pressurized ventilatory adjuncts.)

Operational Assumptions for Analysis of Each Mode of Ventilation Compare the Traditional names for Mode Use the Chatburn Classification (8 types) What are the Physician’s or Protocol orders What limits are imposed on the breath sequence Advantages Disadvantages

Choosing Ventilator Mode “Control” modes: VC-CMV & PC-CMV Volume control (ie Assist / Control): VC (AC) Pressure control: PC PRVC or Autoflow Mixed PC or VC Synchronized Intermittent Mandatory Ventilation (SIMV) with support (controlled and spontaneous) “Spontaneous” Modes Pressure Support (PS) APRV, BiVent or BiLevel CPAP T-Piece

Old Mode Limits Vol A/C VC-CMV Vol SIMV VC-IMV Press A/C Press SIMV Chatburn Mode Settings Limits Advantages Dis-advantages Vol A/C VC-CMV f, VT, FIO2,Peep Flow, PIP, Vol Easy to understand Pt. sedation barotrauma Vol SIMV VC-IMV Press A/C f, TI, PIP FIO2,Peep Safer, more natural VT varies with CL & Raw Press SIMV PSV Flow Press SIMV + PS

Now, describe the pt…Size does matter Set inspiratory percentage to achieve an I/E ratio of greater than or equal to 1:1.5 (Ideally; 1:2 or better) BSA = body surface area IBW = ideal body weight. * In patients with neuromuscular disorders or cerebral disorders, a VT of as high as 15 mL/kg may be required.

BSA vs. IBW for Volume Target Minute Ventilation VE Men VE = 4 x BSA Women VE = 3.5 x BSA IBW in kg. x #ml protocol for VT

Determining Ideal Body Weight: Women IBW (lbs) = 105 + 5(H – 60) Men IBW (lbs) = 106 + 6(H – 60) to convert to kg, divide by 2.2.

Initial Tidal Volume Settings for VC-CMV & VC-IMV Modes Normal pulmonary mechanics: VT = 10-12 ml/kg—f = 8-12/min Restrictive lung disease: VT = 4-8 ml/kg—f = 15-25/min Obstructive lung disease: VT = 8-10 ml/kg—f = 8-12/min ---Hess and Kacmarek (2002)

Question Mode characteristics What parameters do I have to set or get orders for? What initiates the breath? What terminates a breath (i.e. how will the ventilator cycle)? What are the flow characteristics? What are the pressure characteristics? What are the determinants of VT? What are the Limits?

Volume control (VC) Orders: RR, VT, (VI:E), FIO2 +/- PEEP Initiate: Patient (pressure vs. flow triggered) or controlled; breaths beyond set rate to get FULL set VT Termination: VT (and V)- volume-cycled Flow: constant (40-120 L/min); can be variable on some vents Pressure: Increases as lungs distend until inspiration terminates; varies with load VT or VE: Fixed

Flow Patterns

Volume Control (top line)

Suggested Initial Ventilator Settings for COPD (Sethi, 2000; Hess, 2002; Saura, 2002) Parameter Recommendation Mode Assist/control (pressure-target, PC-CMV, preferred over volume-target, VC-CMV VT 8 to 10 mL/kg (targeted to keep Pplateau as low as possible < 30 cm H2O) f 8 to 10 breaths/min TI 0.6 to 1.2 sec Flow >60 L/min (up to 100 L/min) Flow pattern - descending ramp PEEP < 5 cm H2O or < 85 % of auto-PEEP measured (initially) FIO2 < 0.5 (if possible)

Pressure Control (PC) Orders: f, Pinsp level above PEEP, TI , FIO2 +/- PEEP Initiate: Patient or controlled; breaths beyond set f get full set PIP/I time (unless SIMV) Termination: Set pressure at the I time Flow: decelerating rate; can vary with patient demand Pressure: constant Volume, I time; varies with lung compliance (CL = V/P)

Required Setting Selection and Variables during Pressure Ventilation Mode Name Trigger Cycle PSV Patient Flow PC-CMV Time/patient Time NAVA Time/Flow APRV or Bilevel PAP Servo-controlled pressure ventilation: Time/patient Flow PAug Patient Volume/Flow PRVC Time/patient Time VS patient Flow

Pressure Support (PS) Orders: Pinsp above PEEP, FIO2 +/- PEEP Initiate: Patient Termination: Flow is 25% of max (flow cycled) Flow: decelerating rate; patient can increase Pressure: constant Volume: varies with pressure, effort, and compliance

Names for PRVC on Different Ventilators Hamilton Galileo Adaptive pressure ventilation Viasys Avea PRVC Dräger E-4 Autoflow Newport E500 Volume targeted pressure control Servo 300 and Servoi PRVC

Names for VS on Different Ventilators Ventilator Name VS Name Servo 300 and Servoi Volume Support Newport E-500 Volume target pressure- support (VTPS)

Pressure Control (top) Pressure Support (bottom)

CPAP (via ETT) Orders: FIO2 and “EEP” (baseline) level Initiate: patient Termination: patient Flow: patient Pressure: oscillates around the CPAP Volume: varies with pressure, effort and compliance Patient breathing spontaneously at a higher end expiratory pressure

CPAP (bottom line)

T-piece (T-tube) Orders: FIO2 Initiate: Patient Termination: Patient Flow: Patient Pressure: negative with inspiration Volume: varies with effort and compliance Spontaneous breathing through an ETT Remember Raw

SIMV(VC or PC)/PS Orders: f, VT (VI:E) or Pinsp, FIO2 +/- PEEP; add PS (for breaths beyond set rate) Initiate: Patient or controlled (synchronized) Termination: Controlled breath (VC or PC) PS breath (beyond set f): Flow is ~25% of peak flow (flow-cycled) Flow: PS breath: Decelerating rate; varies with demand

SIMV(VC or PC)/PS Pressure: VT: Controlled breath (VC or PC) PS breath: constant at whatever you set VT: PS breath: patient effort; lung compliance Try to match spontaneous VT with controlled VT

SIMV/T-piece (middle line)

Basic Modes: A Quick Reference Orders (FIO2, PEEP) Initiate (trigger) Terminate (cycled) Flow Pressure VT VC VT, RR, V(flow) (P)atient (C)ontrolled constant (usually) rising fixed PC Pinsp, RR I time P, C decelerating varies with compliance SIMV PC or VC; PS, CPAP P, C (synch with patient) VT or Constant or decelerating Rising or constant Fixed or variable PS/bilevel Pinsp P 25% of peak flow compliance, effort CPAP “PEEP” Patient determines around PEEP T-tube FIO2 around atm

Managing the ventilated patient Initial orders Reading the vent board (yes, you’re supposed to do that in clinic when you are assessing the pt.) Lung mechanics VE, NIF, RSBI, Raw and CL Ventilator adjustments for O2 and CO2 Revisit Goal(s) (stay awake)

Remember, what were the goals in the first place…

After Lunch Modes Jeopardy and Vent Set-ups