Initiation of Mechanical VentilationInitial Ventilator SettingsModeFull Ventilatory Support (FVS)Assumes essentially all the work of breathingMajority initially require FVSAssist Control (A/C)SIMV if rate is 12 BPM or higher (Chang)

Partial Ventilatory Support (PVS)Provides less than total amount of work of breathingCommon during weaningSIMV at lower rates (usually

Initiation of Mechanical VentilationInitial Ventilator SettingsRespiratory RateA range of 8 12 breaths per minute (BPM)Normal respiratory rate is 12-18 BPMRespiratory rate is chosen in conjunction with tidal volume to provide an acceptable minute ventilation Normal VE is 5-10 L/minEstimated by using 100 mL/kg IBWABG needed to assess effectiveness of initial settingsPaCO2 >45PaCO2

Initiation of Mechanical VentilationInitial Ventilator SettingsTidal VolumeA range of 6 12 ml/kg IBW is used for adults 10 12 ml/kg IBW (normal lung function)8 10 ml/kg IBW (obstructive lung disease)6 8 ml/kg IBW (ARDS)

A range of 5 10 ml/kg IBW is used for infants and children (Pilbeam)

Ideal Body Weight CalculationMale IBW in lb:106 + [6 x (height in inches 60)]Female IBW in lb:105 + [5 x (height in inches 60)]NOTE: spontaneous VT for an adult is 5 7 ml/kg of IBW

Initiation of Mechanical VentilationInitial Ventilator SettingsTidal Volume

Ideally, a tidal volume should be chosen that maintains a PPlat

Initiation of Mechanical VentilationInitial Ventilator SettingsFiO2Initially 100%Severe hypoxemiaAbnormal cardiopulmonary functionsPost-resuscitationSmoke inhalationARDS

After stabilization, attempt to keep FiO2

Initiation of Mechanical VentilationInitial Ventilator SettingsFiO2Patients with mild hypoxemia or normal cardiopulmonary functionDrug overdoseUncomplicated postoperative recoveryFiO2 of 40%Same FiO2 prior to mechanical ventilation

Initiation of Mechanical VentilationInitial Ventilator SettingsPositive End Expiratory Pressure (PEEP)Increases FRCUseful to treat refractory hypoxemiaInitially set at 5 cm H2OSubsequent changes are based on ABG results

ContraindicationsHypotensionElevated ICPUncontrolled pneumothorax

Initiation of Mechanical VentilationInitial Ventilator SettingsI:E RatioRelationship between inspiratory and expiratory timeUsually 1:1.5 1:4 (TI of 0.8 1.2 seconds)

Principle Determinants of TI and I:E RatioPeak flow ( I)Inspiratory time (TI)Inspiratory time percentage (TI%)Respiratory rate (f )Minute ventilation - E (VT x f )

Initiation of Mechanical VentilationInitial Ventilator SettingsAdjusting I:E Ratio

I : I TI smaller I:E ratio I : I TI larger I:E ratio

VT: VT TI larger I:E ratioVT: VT TI smaller I:E ratio

f : RR TE larger I:E ratiof : RR TE smaller I:E ratio

TI%: TI% larger I:E ratioe.g., = TI% of 20% = 1:4, TI% 0f 25% 1:3

Initiation of Mechanical VentilationInitial Ventilator SettingsFlow PatternInitially, a decelerating flow pattern is used; others result in higher airway pressure

Initiation of Mechanical VentilationInitial Ventilator SettingsFlow PatternSome clinician choose to use a constant (square) flow pattern initially because it enables the clinician to obtain baseline measurements of lung compliance and airway resistance (Oakes Ventilation Management; ch.5)

Initiation of Mechanical VentilationInitial Ventilator SettingsFlow RateSet at 40 100 L/min (volume ventilation)

Set I patients peak inspiratory demand and to deliver an I:E ratio of 1:1.5 1:4

Initiation of Mechanical VentilationVentilator Alarm SettingsHigh Minute VentilationSet at 1-2 L/min or 10%-15% above baseline minute ventilationPatient is becoming tachypneic (respiratory distress)Ventilator is self-triggering

High Respiratory Rate AlarmSet 10 15 BPM over observed respiratory ratePatient is becoming tachypneic (respiratory distress)Ventilator self-triggering

Initiation of Mechanical VentilationVentilator Alarm SettingsLow Exhaled Tidal Volume AlarmSet 100 ml or 10%-15% lower than expired mechanical tidal volumeCausesSystem leak Circuit disconnectionET Tube cuff leak

Low Exhaled Minute Ventilation AlarmSet at 1-2 L/min or 10%-15% below minimum SIMV or A/C backup minute ventilationCausesSystem leakCircuit disconnectionET Tube cuff leak

Initiation of Mechanical VentilationVentilator Alarm SettingsHigh Inspiratory Pressure AlarmSet 10 15 cm H2O above PIPInspiration is terminated when triggeredCommon causes:Water in circuitKinking or biting of ET TubeSecretions in the airwayBronchospasmTension pneumothoraxDecrease in lung compliance Increase in airway resistanceCoughing

Initiation of Mechanical VentilationVentilator Alarm SettingsLow Inspiratory Pressure AlarmSet 10 15 cm H2O below observed PIPCausesSystem leakCircuit disconnectionET Tube cuff leak

High/Low PEEP/CPAP Alarm (baseline alarm)High: Set 3-5 cm H2O above PEEPCircuit or exhalation manifold obstructionAuto PEEPLow: Set 3-5 cm H2O below PEEPCircuit disconnect

Initiation of Mechanical VentilationVentilator Alarm SettingsApnea AlarmSet with a 15 20 second time delayIn some ventilators, this triggers an apnea ventilation mode

High/Low FiO2 AlarmHigh: 5% - 10% over the analyzed FiO2Low: 5% - 10% below the analyzed FiO2

High/Low Temperature AlarmHeated humidificationHigh: No higher than 37 CLow: No lower than 30 C