PATRICK GERARD L. MORAL, M.D.. T OPICS Arterial Blood GasArterial Blood Gas Ventilatory SupportVentilatory Support Arterial Blood GasArterial Blood.

PATRICK GERARD L. MORAL, M.D.PATRICK GERARD L. MORAL, M.D.PATRICK GERARD L. MORAL, M.D.PATRICK GERARD L. MORAL, M.D.

TTOPICSOPICSTTOPICSOPICS

• Arterial Blood GasArterial Blood Gas• Ventilatory SupportVentilatory Support

• Arterial Blood GasArterial Blood Gas• Ventilatory SupportVentilatory Support

AABGBGAABGBG

• Acid - base statusAcid - base status• ventilatory statusventilatory status• oxygenation statusoxygenation status

• Acid - base statusAcid - base status• ventilatory statusventilatory status• oxygenation statusoxygenation status

NNORMAL VALUESORMAL VALUESNNORMAL VALUESORMAL VALUES

• pHpH 7.35 - 7.457.35 - 7.45• paCO2paCO2 35 - 45 35 - 45• paO2paO2 80 - 100 80 - 100• HCO3HCO3 22 - 26 22 - 26• O2 satO2 sat > 95% > 95%

• pHpH 7.35 - 7.457.35 - 7.45• paCO2paCO2 35 - 45 35 - 45• paO2paO2 80 - 100 80 - 100• HCO3HCO3 22 - 26 22 - 26• O2 satO2 sat > 95% > 95%

AACID BASE STATUSCID BASE STATUSAACID BASE STATUSCID BASE STATUS

• < 7.35 - acidosis< 7.35 - acidosis– increased CO2increased CO2-- respiratory respiratory– decreased HCO3decreased HCO3 -- metabolic metabolic

• > 7.45 - alkalosis> 7.45 - alkalosis– decreased CO2decreased CO2 -- respiratoryrespiratory– increased HCO3 increased HCO3 -- metabolicmetabolic

• < 7.35 - acidosis< 7.35 - acidosis– increased CO2increased CO2-- respiratory respiratory– decreased HCO3decreased HCO3 -- metabolic metabolic

• > 7.45 - alkalosis> 7.45 - alkalosis– decreased CO2decreased CO2 -- respiratoryrespiratory– increased HCO3 increased HCO3 -- metabolicmetabolic

VVENTILATIONENTILATIONVVENTILATIONENTILATION

• increased CO2 - hypoventialtionincreased CO2 - hypoventialtion• decreased CO2 - hyperventilationdecreased CO2 - hyperventilation

• increased CO2 - hypoventialtionincreased CO2 - hypoventialtion• decreased CO2 - hyperventilationdecreased CO2 - hyperventilation

CCOMPENSATIONOMPENSATIONCCOMPENSATIONOMPENSATION

• AcidosisAcidosis– respiratory acidosis (inc. CO2) - inc HCO3respiratory acidosis (inc. CO2) - inc HCO3– metabolic acidosis (dec. HCO3) - dec CO2metabolic acidosis (dec. HCO3) - dec CO2

• AlkalosisAlkalosis– respiratory alkalosis (dec. CO2) - dec. respiratory alkalosis (dec. CO2) - dec.

HCO3HCO3– metabolic alkalosis (inc. HCO3) - inc. CO2metabolic alkalosis (inc. HCO3) - inc. CO2

• AcidosisAcidosis– respiratory acidosis (inc. CO2) - inc HCO3respiratory acidosis (inc. CO2) - inc HCO3– metabolic acidosis (dec. HCO3) - dec CO2metabolic acidosis (dec. HCO3) - dec CO2

• AlkalosisAlkalosis– respiratory alkalosis (dec. CO2) - dec. respiratory alkalosis (dec. CO2) - dec.

HCO3HCO3– metabolic alkalosis (inc. HCO3) - inc. CO2metabolic alkalosis (inc. HCO3) - inc. CO2

CCOMPENSATIONOMPENSATIONCCOMPENSATIONOMPENSATION

• PartiallyPartially– the pH does not return to normalthe pH does not return to normal

• FullyFully– the pH returns to the normal rangethe pH returns to the normal range

• PartiallyPartially– the pH does not return to normalthe pH does not return to normal

• FullyFully– the pH returns to the normal rangethe pH returns to the normal range

pH

< 7.35 7.35 - 7.45 > 7.45

ACIDOSIS NORMALor

COMPENSATED

ALKALOSIS

PaCO235 - 45

< 35

>45

UncompensatedMetabolic Acidosis

PartlyCompensatedMetabolic Acidosis

Respiratory

HCO322 - 26

UncompensatedRespiratoryAcidosis

> 26 < 22

Partly CompensatedRespiratoryAcidosis

CombinedRespiratory andMetabolicAcidosis

PaCO2 35 - 45

> 45

< 35

UncompensatedMetabolic Alkalosis

PartlyCompensatedMetabolic Alkalosis

Respiratory

HCO3 22 - 26

> 26 < 22UncompensatedRespiratoryAlkalosis

PartlyCompensatedRespiratory Alkalosis

CombinedRespiratory andMetabolicAlkalosis

pH

< 7.4 > 7.4

Normal orCompensatedAcidosis

Normal orCompensatedAlkalosis

PaCO2

< 35

> 45

35 - 45

Normal Acid-Base

CompensatedRespiratoryAcidosis

CompensatedMetabolicAcidosis

CompensatedRespiratoryAlkalosis

CompensatedMetabolicAlkalosis

Figure 1. Summary Algorithm for Acid-Base Interpretation

OOXYGENATIONXYGENATIONOOXYGENATIONXYGENATION

• at room airat room air– < 80 mmHg < 80 mmHg -- hypoxemichypoxemic– 80 - 10080 - 100 -- normal oxygenationnormal oxygenation

• with supplemental oxygenationwith supplemental oxygenation– < 80 mm Hg< 80 mm Hg -- inadequateinadequate– 80 - 100 mmHg80 - 100 mmHg -- adequateadequate– > 100 mmHg> 100 mmHg -- more than adequatemore than adequate

• at room airat room air– < 80 mmHg < 80 mmHg -- hypoxemichypoxemic– 80 - 10080 - 100 -- normal oxygenationnormal oxygenation

• with supplemental oxygenationwith supplemental oxygenation– < 80 mm Hg< 80 mm Hg -- inadequateinadequate– 80 - 100 mmHg80 - 100 mmHg -- adequateadequate– > 100 mmHg> 100 mmHg -- more than adequatemore than adequate

IINTUBATIONNTUBATIONIINTUBATIONNTUBATION

• Prevention of upper airway Prevention of upper airway obstructionobstruction

• Protection against aspirationProtection against aspiration• Facilitating tracheobronchial toiletFacilitating tracheobronchial toilet• Providing a closed system for Providing a closed system for

mechanical ventilationmechanical ventilation

• Prevention of upper airway Prevention of upper airway obstructionobstruction

• Protection against aspirationProtection against aspiration• Facilitating tracheobronchial toiletFacilitating tracheobronchial toilet• Providing a closed system for Providing a closed system for

mechanical ventilationmechanical ventilation

VENTILATORY VENTILATORY FAILUREFAILURE

VENTILATORY VENTILATORY FAILUREFAILURE

REDUCED REDUCED CENTRAL DRIVECENTRAL DRIVE

REDUCED REDUCED CENTRAL DRIVECENTRAL DRIVE

IMPAIRED INSPIRATORY IMPAIRED INSPIRATORY MUSCLE PERFORMANCEMUSCLE PERFORMANCEIMPAIRED INSPIRATORY IMPAIRED INSPIRATORY MUSCLE PERFORMANCEMUSCLE PERFORMANCE

EXCESSIVE EXCESSIVE RESPIRATORY RESPIRATORY WORKLOADWORKLOAD

EXCESSIVE EXCESSIVE RESPIRATORY RESPIRATORY WORKLOADWORKLOAD

OOBJECTIVESBJECTIVESOOBJECTIVESBJECTIVES

• To support pulmonary gas To support pulmonary gas exchangeexchange– alveolar ventilationalveolar ventilation– arterial oxygenationarterial oxygenation

• To increase lung volumeTo increase lung volume• To reduce or manipulate work of To reduce or manipulate work of

breathingbreathing

• To support pulmonary gas To support pulmonary gas exchangeexchange– alveolar ventilationalveolar ventilation– arterial oxygenationarterial oxygenation

• To increase lung volumeTo increase lung volume• To reduce or manipulate work of To reduce or manipulate work of

breathingbreathing

PHYSIOLOGICAL

OOBJECTIVESBJECTIVESOOBJECTIVESBJECTIVES

• To reverse hypoxemiaTo reverse hypoxemia• To reverse acute respiratory acidosisTo reverse acute respiratory acidosis• To relieve respiratory distressTo relieve respiratory distress• To prevent / reverse atelectasisTo prevent / reverse atelectasis• To reverse ventilatory muscle fatigueTo reverse ventilatory muscle fatigue• To permit sedation / neuromuscular blockadeTo permit sedation / neuromuscular blockade• To decrease myocardial oxygen consumptionTo decrease myocardial oxygen consumption• To reduce intracranial pressureTo reduce intracranial pressure• To stabilize chest wallTo stabilize chest wall

• To reverse hypoxemiaTo reverse hypoxemia• To reverse acute respiratory acidosisTo reverse acute respiratory acidosis• To relieve respiratory distressTo relieve respiratory distress• To prevent / reverse atelectasisTo prevent / reverse atelectasis• To reverse ventilatory muscle fatigueTo reverse ventilatory muscle fatigue• To permit sedation / neuromuscular blockadeTo permit sedation / neuromuscular blockade• To decrease myocardial oxygen consumptionTo decrease myocardial oxygen consumption• To reduce intracranial pressureTo reduce intracranial pressure• To stabilize chest wallTo stabilize chest wall

CLINICAL

• 700 - 900 mL700 - 900 mL• 15 LPM (self-inflating)15 LPM (self-inflating)• augment VTaugment VT

• 700 - 900 mL700 - 900 mL• 15 LPM (self-inflating)15 LPM (self-inflating)• augment VTaugment VT

AAMBUBAG VENTILATIONMBUBAG VENTILATIONAAMBUBAG VENTILATIONMBUBAG VENTILATION

MMODESODESMMODESODES

• Assist - ControlAssist - Control• SIMVSIMV• PSVPSV• CPAPCPAP• Servo-controlled Servo-controlled

• Assist - ControlAssist - Control• SIMVSIMV• PSVPSV• CPAPCPAP• Servo-controlled Servo-controlled

BBASICASICBBASICASIC

VVAA = V = VTT - V - VDD

VVAA = V = VEE - V - VDD

VVAA = V = VTT - V - VDD

VVAA = V = VEE - V - VDD VAVA

VTVT

• Hook to mechanical ventilator with Hook to mechanical ventilator with the following set-up:the following set-up:– mode: assist - controlmode: assist - control– VT: 500 mLVT: 500 mL– BUR: 15/ minuteBUR: 15/ minute– FiO2: 100 %FiO2: 100 %

• ABG 30 minutes after hooking to MVABG 30 minutes after hooking to MV• In-line nebulization q 6In-line nebulization q 6

• Hook to mechanical ventilator with Hook to mechanical ventilator with the following set-up:the following set-up:– mode: assist - controlmode: assist - control– VT: 500 mLVT: 500 mL– BUR: 15/ minuteBUR: 15/ minute– FiO2: 100 %FiO2: 100 %

• ABG 30 minutes after hooking to MVABG 30 minutes after hooking to MV• In-line nebulization q 6In-line nebulization q 6

OORDERSRDERSOORDERSRDERS

FiO2FiO2FiO2FiO2

• 100 %100 %• dependent on target PaO2, dependent on target PaO2,

hemodynamic status, MAP, PEEP hemodynamic status, MAP, PEEP levellevel

• 100 %100 %• dependent on target PaO2, dependent on target PaO2,

hemodynamic status, MAP, PEEP hemodynamic status, MAP, PEEP levellevel

OOXYGEN CONTENT XYGEN CONTENT OOXYGEN CONTENT XYGEN CONTENT

CaO2 =CaO2 =

1.34 mL x Hgb x SaO2 + .OO3 mL O2 x 1.34 mL x Hgb x SaO2 + .OO3 mL O2 x PaO2PaO2

CaO2 =CaO2 =

1.34 mL x Hgb x SaO2 + .OO3 mL O2 x 1.34 mL x Hgb x SaO2 + .OO3 mL O2 x PaO2PaO2

TTIDAL VOLUMEIDAL VOLUMETTIDAL VOLUMEIDAL VOLUME

• Physiologic: 5 - 7 mL / KgPhysiologic: 5 - 7 mL / Kg• MV: 10 - 15 mL / KgMV: 10 - 15 mL / Kg• alveolar distending pressure: 35 alveolar distending pressure: 35

cm Hcm H22OO

• Physiologic: 5 - 7 mL / KgPhysiologic: 5 - 7 mL / Kg• MV: 10 - 15 mL / KgMV: 10 - 15 mL / Kg• alveolar distending pressure: 35 alveolar distending pressure: 35

cm Hcm H22OO

BBASICASICBBASICASIC

VVAA = V = VTT - V - VDD

VVAA = V = VEE - V - VDD

VVAA = V = VTT - V - VDD

VVAA = V = VEE - V - VDD VAVA VDVD

mechanical

anatomic

alveolar

CCARDIAC OUTPUTARDIAC OUTPUTCCARDIAC OUTPUTARDIAC OUTPUT

hyperinflation

Increased pulmonary vascular resistance

Increased RV afterload

Decreased RV output

Decreased LV preload

Decreased LV output

PPV

• 4 to 20 / minute4 to 20 / minute• 8 to 12 / minute8 to 12 / minute• dependent on:dependent on:

– delivered VTdelivered VT– metabolic ratemetabolic rate– target PaCO2target PaCO2– level of spontaneous ventilationlevel of spontaneous ventilation

• 4 to 20 / minute4 to 20 / minute• 8 to 12 / minute8 to 12 / minute• dependent on:dependent on:

– delivered VTdelivered VT– metabolic ratemetabolic rate– target PaCO2target PaCO2– level of spontaneous ventilationlevel of spontaneous ventilation

RRESPIRATORY RATEESPIRATORY RATERRESPIRATORY RATEESPIRATORY RATE

• 40 to 100 L/ minute40 to 100 L/ minute• determined by level of determined by level of

spontaneous breathing effortspontaneous breathing effort

• 40 to 100 L/ minute40 to 100 L/ minute• determined by level of determined by level of

spontaneous breathing effortspontaneous breathing effort

FFLOW RATELOW RATEFFLOW RATELOW RATE

• Inspiratory time: 0.8 to 1.2 sInspiratory time: 0.8 to 1.2 s• I:E 1:2 to 1:1.5I:E 1:2 to 1:1.5

• Inspiratory time: 0.8 to 1.2 sInspiratory time: 0.8 to 1.2 s• I:E 1:2 to 1:1.5I:E 1:2 to 1:1.5

IINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIOIINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIO

• Respiratory rate: 20 / minuteRespiratory rate: 20 / minute

60 seconds / 20 = 3 seconds 60 seconds / 20 = 3 seconds = T= Ttottot

at an I:E ratio of 1:2:at an I:E ratio of 1:2:

TTII = 1 second = 1 second

TTEE = 2 seconds = 2 seconds

• Respiratory rate: 20 / minuteRespiratory rate: 20 / minute

60 seconds / 20 = 3 seconds 60 seconds / 20 = 3 seconds = T= Ttottot

at an I:E ratio of 1:2:at an I:E ratio of 1:2:

TTII = 1 second = 1 second

TTEE = 2 seconds = 2 seconds

IINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIOIINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIO

• Respiratory rate: 30 / minuteRespiratory rate: 30 / minute

60 seconds / 30 = 2 seconds 60 seconds / 30 = 2 seconds = T= Ttottot

at an I:E ratio of 1:1:at an I:E ratio of 1:1:

TTII = 1 second = 1 second

TTEE = 1 second = 1 second

• Respiratory rate: 30 / minuteRespiratory rate: 30 / minute

60 seconds / 30 = 2 seconds 60 seconds / 30 = 2 seconds = T= Ttottot

at an I:E ratio of 1:1:at an I:E ratio of 1:1:

TTII = 1 second = 1 second

TTEE = 1 second = 1 second

IINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIOIINSPIRATORY TIME / I:E RATIONSPIRATORY TIME / I:E RATIO

• -0.5 to 1.5 cm H20-0.5 to 1.5 cm H20• most sensitive level that prevents most sensitive level that prevents

self-cyclingself-cycling

• -0.5 to 1.5 cm H20-0.5 to 1.5 cm H20• most sensitive level that prevents most sensitive level that prevents

self-cyclingself-cycling

SSENSITIVITYENSITIVITYSSENSITIVITYENSITIVITY

• High pressureHigh pressure• Low pressureLow pressure

• High pressureHigh pressure• Low pressureLow pressure

PPRESSURE ALARMSRESSURE ALARMSPPRESSURE ALARMSRESSURE ALARMS

• Low pressureLow pressure– check connections between tubings check connections between tubings

and patientand patient– deflated cuff deflated cuff – extubationextubation

• Low pressureLow pressure– check connections between tubings check connections between tubings

and patientand patient– deflated cuff deflated cuff – extubationextubation

PPRESSURE ALARMSRESSURE ALARMSPPRESSURE ALARMSRESSURE ALARMS

• High pressureHigh pressure– bronchoconstrictionbronchoconstriction– airway obstructionairway obstruction– barotraumabarotrauma– right main bronchus obstructionright main bronchus obstruction– kinked endotracheal tubekinked endotracheal tube

• High pressureHigh pressure– bronchoconstrictionbronchoconstriction– airway obstructionairway obstruction– barotraumabarotrauma– right main bronchus obstructionright main bronchus obstruction– kinked endotracheal tubekinked endotracheal tube

PPRESSURE ALARMSRESSURE ALARMSPPRESSURE ALARMSRESSURE ALARMS

• Cascade humidifierCascade humidifier• heats carrier gas to 37 C heats carrier gas to 37 C • holds 44 mg H20 / L gasholds 44 mg H20 / L gas• water replacementwater replacement• increases volume and decreases increases volume and decreases

viscosity of the sputumviscosity of the sputum

• Cascade humidifierCascade humidifier• heats carrier gas to 37 C heats carrier gas to 37 C • holds 44 mg H20 / L gasholds 44 mg H20 / L gas• water replacementwater replacement• increases volume and decreases increases volume and decreases

viscosity of the sputumviscosity of the sputum

HHUMIDIFICATIONUMIDIFICATIONHHUMIDIFICATIONUMIDIFICATION

• Chest radiographChest radiograph• Arterial blood gasArterial blood gas• OximetryOximetry• CapnographyCapnography

• Chest radiographChest radiograph• Arterial blood gasArterial blood gas• OximetryOximetry• CapnographyCapnography

AANCILLARYNCILLARYAANCILLARYNCILLARY

• BarotraumaBarotrauma• Oxygen toxicityOxygen toxicity• Patient-ventilator asynchronyPatient-ventilator asynchrony• CardiovascularCardiovascular• RenalRenal• GastrointestinalGastrointestinal

• BarotraumaBarotrauma• Oxygen toxicityOxygen toxicity• Patient-ventilator asynchronyPatient-ventilator asynchrony• CardiovascularCardiovascular• RenalRenal• GastrointestinalGastrointestinal

CCOMPLICATIONS OMPLICATIONS CCOMPLICATIONS OMPLICATIONS