Mechanical ventilationMechanical ventilation

MECHANICAL VENTILATIONMECHANICAL VENTILATION

‘ ‘When you cannot breathe, nothing else When you cannot breathe, nothing else matters.’matters.’

Its not a Magic, but simple Logic.. Its not a Magic, but simple Logic..

The BASICS!!The BASICS!!

AnatomyAnatomy• Upper Respiratory TractUpper Respiratory Tract

– Humidifies inhaled gasesHumidifies inhaled gases– Site of most resistance to airflowSite of most resistance to airflow

• Lower Respiratory TractLower Respiratory Tract– Conducting zone/airways (Anatomic dead Conducting zone/airways (Anatomic dead

space)space)– Respiratory zone/ bronchioles and alveoli Respiratory zone/ bronchioles and alveoli

(Gas exchange)(Gas exchange)

The BASICS!! (Cont’d)The BASICS!! (Cont’d)

PhysiologyPhysiologyNegative pressure circuitNegative pressure circuit

– Gradient between mouth and pleural space Gradient between mouth and pleural space is the driving pressureis the driving pressure

– need to overcome resistanceneed to overcome resistance– maintain alveolus openmaintain alveolus open

The BASICS!! (Cont’d)The BASICS!! (Cont’d)

• Ventilation?Ventilation?

• Respiration?Respiration?

• External Respiration?External Respiration?

• Internal Respiration?Internal Respiration?O2CO2

DefinitionDefinition

Mechanical ventilator is an Mechanical ventilator is an apparatus which can replace apparatus which can replace normal mechanism of breathing normal mechanism of breathing either by providing intermittent or either by providing intermittent or continuous flow of oxygen or air continuous flow of oxygen or air under pressure, which is connected under pressure, which is connected to the patient by a tube inserted to the patient by a tube inserted through mouth, the nose or an through mouth, the nose or an opening in the trachea.opening in the trachea.

Mechanical VentilationMechanical Ventilation

1.1. Indications for Intubation and VentilationIndications for Intubation and Ventilation2.2. Principles of Mechanical VentilationPrinciples of Mechanical Ventilation3.3. Modes & Patterns of VentilationModes & Patterns of Ventilation4.4. Ventilator Dependence: Complications Ventilator Dependence: Complications 5.5. Liberation from Mechanical Ventilation: WeaningLiberation from Mechanical Ventilation: Weaning6.6. TroubleshootingTroubleshooting7.7. Arterial Blood GasesArterial Blood Gases

Indications for Mechanical VentilationIndications for Mechanical Ventilation

“….An opening must be attempted in the “….An opening must be attempted in the trunk of the trachea, into which a tube or trunk of the trachea, into which a tube or cane should be put; You will then blow into cane should be put; You will then blow into this so that lung may rise again….And the this so that lung may rise again….And the heart becomes strong….”heart becomes strong….”

Andreas Vesalius (1555)Andreas Vesalius (1555)

INDICATIONSINDICATIONS

• Primary IndicationsPrimary Indications

• Prophylactic IndicationsProphylactic Indications

• Therapeutic IndicationsTherapeutic Indications

Primary IndicationsPrimary Indications

• Acute Respiratory Failure (66%)Acute Respiratory Failure (66%)– Acute Respiratory Distress Syndrome Acute Respiratory Distress Syndrome – Heart Failure (through pulmonary edema/hypertension)Heart Failure (through pulmonary edema/hypertension)– PneumoniaPneumonia– SepsisSepsis– Complications of SurgeryComplications of Surgery– TraumaTrauma

• Coma (15%)Coma (15%)• A/c Exacerbation of COPD(13%)A/c Exacerbation of COPD(13%)• Neuromuscular Disease (5%)Neuromuscular Disease (5%)

Prophylactic IndicationsProphylactic Indications

• ShockShock• PostoperativelyPostoperatively

» Extreme obesityExtreme obesity» Possibility of sepsisPossibility of sepsis» COPD with upper abdominal surgeryCOPD with upper abdominal surgery» Cardiovascular and neurological Cardiovascular and neurological

surgeries surgeries • Acid aspiration syndromeAcid aspiration syndrome

Therapeutic IndicationsTherapeutic Indications

• Resuscitation from cardio respiratory Resuscitation from cardio respiratory arrestarrest

• Hypoventilation /ApneaHypoventilation /Apnea• Drug over dosageDrug over dosage• Neurological dysfunctionNeurological dysfunction• Trauma to chest and lacerated diaphragmTrauma to chest and lacerated diaphragm

Objectives of Mechanical VentilationObjectives of Mechanical Ventilation

• Improves pulmonary gas exchangeImproves pulmonary gas exchange

• Relieves respiratory distressRelieves respiratory distress

• Alter pressure-volume relationsAlter pressure-volume relations

• Permit lung and airway healingPermit lung and airway healing

• Avoid complicationsAvoid complications

TerminologiesTerminologies

• Respiratory RateRespiratory Rate

• Tidal VolumeTidal Volume

• Minute Ventilation (MV=RR x TV)Minute Ventilation (MV=RR x TV)

• FiO2FiO2

• Peak PressurePeak Pressure

Main Determinants!!Main Determinants!!

• Oxygen inOxygen in FFIIOO22 mean alveolar mean alveolar

pressurepressure– PEEPPEEP

• Re-open alveoli Re-open alveoli and and shunt shunt

• Carbon dioxide Carbon dioxide outout ventilationventilation

RRRR tidal volumetidal volume

Modes of VentilatorModes of Ventilator

• Controlled modeControlled modeRR and TV by VentilatorRR and TV by Ventilator

• Assist Control Mode (Mixed Mode)Assist Control Mode (Mixed Mode)Both got their RoleBoth got their Role

• Spontaneous modeSpontaneous mode RR and TV by PatientRR and TV by Patient

CONTROLLED MODE VENTILATIONCONTROLLED MODE VENTILATION

• Pressure Controlled VentilationPressure Controlled Ventilation

• Volume Controlled VentilationVolume Controlled Ventilation

• Time Controlled VentilationTime Controlled Ventilation

Pressure Controlled VentilationPressure Controlled Ventilation

• Pressure cycled breathing, fully ventilator Pressure cycled breathing, fully ventilator controlledcontrolled

• Suited for patients with neuromuscular Suited for patients with neuromuscular diseasesdiseases

• Inspiratory phase stops when preset inspiratory Inspiratory phase stops when preset inspiratory pressure is reachedpressure is reached

Volume Controlled VentilationVolume Controlled Ventilation

• Volume targeted VentilationVolume targeted Ventilation• Inspiratory Cycle ends when TV is deliveredInspiratory Cycle ends when TV is delivered• Ventilator generates sufficient pressure to Ventilator generates sufficient pressure to

deliver set volumedeliver set volume

Time Controlled VentilationTime Controlled Ventilation

• Normal I:E ratio -> 1:2Normal I:E ratio -> 1:2• Prolonged Expiratory phase according to the Prolonged Expiratory phase according to the

underlying pathology i.e. up to 1:3 or 1:4underlying pathology i.e. up to 1:3 or 1:4Inverse Ratio VentilationInverse Ratio Ventilation• Helps prevent alveolar collapseHelps prevent alveolar collapse• Hyperinflation, Auto-PEEP and decreased Hyperinflation, Auto-PEEP and decreased

cardiac outputcardiac output• Use: ARDS with refractory hypoxemia or Use: ARDS with refractory hypoxemia or

hypercapniahypercapnia

ASSIST CONTROL MODE / MIXED MODEASSIST CONTROL MODE / MIXED MODE

• Intermittent Mandatory Ventilation (IMV)Intermittent Mandatory Ventilation (IMV) -- Mandatory Breaths-- Mandatory Breaths

• Synchronized Intermittent Mandatory Synchronized Intermittent Mandatory Ventilation (SIMV)Ventilation (SIMV) -- Synchronized Breaths-- Synchronized Breaths

• SIMV + Pressure SupportSIMV + Pressure Support -- Pressure Support too along with-- Pressure Support too along with

SPONTANEOUS MODESPONTANEOUS MODE

• Pressure Support Ventilation (PSV)Pressure Support Ventilation (PSV) -- Spontaneous inspiratory efforts trigger the ventilator to -- Spontaneous inspiratory efforts trigger the ventilator to

provide a variable flow of gas in order to attain a preset provide a variable flow of gas in order to attain a preset airway pressure. airway pressure. Machine assist and augment the Machine assist and augment the spontaneous breathing efforts of patientspontaneous breathing efforts of patient

• Continuous Positive Airway Pressure (CPAP)Continuous Positive Airway Pressure (CPAP)No machine breaths delivered No machine breaths delivered Allows spontaneous breathing at elevated baseline Allows spontaneous breathing at elevated baseline pressurepressurePatient controls rate and tidal volumePatient controls rate and tidal volume

CMVCMV

ACV/SIMVACV/SIMV

PSVPSV

Setting a VentilatorSetting a Ventilator

Settings vary with Age, Weight and Settings vary with Age, Weight and underlying Pathology of the patientunderlying Pathology of the patient

The required Ventilator settings are :-The required Ventilator settings are :-

• Tidal volumeTidal volume• FiOFiO22

• Respiratory RateRespiratory Rate• Minute VolumeMinute Volume• I:E RatioI:E Ratio• Pause timePause time• PEEP, ZEEP & NEEPPEEP, ZEEP & NEEP• Trigger sensitivityTrigger sensitivity

Tidal Volume (VTidal Volume (VTT))

Tidal volume Tidal volume 8-10ml/Kg8-10ml/Kg

Small tidal volume inSmall tidal volume inARDSARDSBronchospasmBronchospasm

Large tidal volume causesLarge tidal volume causesIncreased airway pressureIncreased airway pressureBarotraumasBarotraumas

FiOFiO22

FiOFiO22 (Oxygen concentration) (Oxygen concentration)Expresses as percentage or decimalsExpresses as percentage or decimalsSettings from 21% to 100% (0.21 to 1.0)Settings from 21% to 100% (0.21 to 1.0)FiOFiO22 of 0.5 or less –minimize oxygen of 0.5 or less –minimize oxygen toxicitytoxicity

Target PaO2 isTarget PaO2 is 60mm of Hg or 60mm of Hg or SpO2 90% in ABG , SpO2 90% in ABG , SpO2 95% in pulse oximeter SpO2 95% in pulse oximeter With minimum possible FiOWith minimum possible FiO22

Respiratory Rate (RR)Respiratory Rate (RR)

Respiratory Rate (RR) or FrequencyRespiratory Rate (RR) or Frequency > Set rate depends on age of patient> Set rate depends on age of patient Newborn - 30-40/mtNewborn - 30-40/mt Children - 20-30/mtChildren - 20-30/mt Adult - 10-15/mtAdult - 10-15/mt

Reduce rate in patients with COPDReduce rate in patients with COPD

Minute Volume [MV]Minute Volume [MV]

Minute volume = Tidal volume X R.R.Minute volume = Tidal volume X R.R.

I:E RatioI:E Ratio

Inspiratory time and I:E ratioInspiratory time and I:E ratio• Determines duration of inspiration and Determines duration of inspiration and

oxygenation oxygenation

Newborn Newborn 0.3-0.5 sec0.3-0.5 secInfant and childrenInfant and children 0.5-0.8 sec0.5-0.8 secAdultAdult up to 1.5 secup to 1.5 sec

I:E Ratio (Cont’d)I:E Ratio (Cont’d)

Normal I:E - 1:2 (is physiological)Normal I:E - 1:2 (is physiological)

COPDCOPD - 1:3 to 1:4 - 1:3 to 1:4

1:1 or 2:1 or more is called 1:1 or 2:1 or more is called Inverse Ratio VentilationInverse Ratio Ventilation Used in ARDS and in Used in ARDS and in Refractory HypoxemiaRefractory Hypoxemia

Trigger sensitivityTrigger sensitivity• How does the Ventilator know when to give a How does the Ventilator know when to give a

breath??? breath??? “Trigger”“Trigger”– Patient effortPatient effort

• The patient’s effort can be “sensed” as a change in The patient’s effort can be “sensed” as a change in pressure or a change in flow (in the circuit)pressure or a change in flow (in the circuit)

Helps to the initiation of breath by patientHelps to the initiation of breath by patient - Ventilator sense the pressure drop in the system- Ventilator sense the pressure drop in the system - Set between -2 to -20 cm of H- Set between -2 to -20 cm of H22OO - Start from -2, incrementally increase- Start from -2, incrementally increase

Flow rateFlow rate

Flow rateFlow rateSpeed with which the Tidal Volume is Speed with which the Tidal Volume is delivereddeliveredAn important determinant of patient An important determinant of patient comfortcomfort

Normal rateNormal rate - 40-60 L/ Mt - 40-60 L/ Mt - 4X Minute Ventilation- 4X Minute Ventilation

End Expiratory PressuresEnd Expiratory Pressures

• PEEP (Positive End Expiratory PEEP (Positive End Expiratory Pressure) Pressure)

• ZEEP (Zero End Expiratory Pressure)ZEEP (Zero End Expiratory Pressure)

• NEEP (Negative End Expiratory NEEP (Negative End Expiratory Pressure) Pressure)

Initial Ventilatory setting Initial Ventilatory setting for an adultfor an adult

ModeMode PCV/ VCV PCV/ VCVFiO2FiO2 0.7-1 decrease to 0.5 or 0.7-1 decrease to 0.5 or less lessTidal Volume (VT) 10ml/KgTidal Volume (VT) 10ml/KgRRRR 10-15 breaths/mt 10-15 breaths/mtTriggerTrigger -2 cm of H2O -2 cm of H2OFlow rateFlow rate 40-60 L/mt 40-60 L/mtI:E I:E 1:2 to 1:3 1:2 to 1:3PEEPPEEP 5 cm of H2O 5 cm of H2OAnalyze Arterial Blood Gas 20 minutes later Analyze Arterial Blood Gas 20 minutes later and adjustand adjust

General rules of General rules of Ventilator ManipulationVentilator Manipulation

To improve oxygenationTo improve oxygenationApply PEEPApply PEEPIncrease Insp. TimeIncrease Insp. TimeIncrease FiOIncrease FiO22

To improve COTo improve CO22 removal removalIncrease RateIncrease RateIncrease Tidal VolumeIncrease Tidal Volume

Care during Mechanical VentilationCare during Mechanical Ventilation

- Sedation and muscle paralysis- Sedation and muscle paralysis- Humidification- Humidification- Chest physiotherapy- Chest physiotherapy- Suctioning Event- Suctioning Event- Nutritional support- Nutritional support- Other general care- Other general care- Prevention of infection- Prevention of infection

Sedation and Muscle paralysisSedation and Muscle paralysis

Sedation and Muscle paralysisSedation and Muscle paralysis• To relieveTo relieve

AwarenessAwarenessAnxietyAnxietyPain and Pain and Patient discomfortPatient discomfort

• Drugs for Analgesia, Sedation, and Muscle Drugs for Analgesia, Sedation, and Muscle relaxationrelaxation

HumidificationHumidification

HumidificationHumidificationProcess of addition of moisture and heat to Process of addition of moisture and heat to inspiratory gasesinspiratory gases

Methods of humidificationMethods of humidificationHeated humidifiersHeated humidifiersNebulizers Nebulizers Heat and Moist Exchangers (HME’s)Heat and Moist Exchangers (HME’s)

In normal breathing humans, In normal breathing humans, Temperature of upper trachea 30-33Temperature of upper trachea 30-33ooCC

Chest PhysiotherapyChest Physiotherapy

Chest PhysiotherapyChest PhysiotherapyUsed to mobilize the secretionUsed to mobilize the secretion

Techniques Includes Techniques Includes Postural drainagePostural drainagePercussionPercussionRib SpringingRib SpringingVibration etc.Vibration etc.

Suctioning EventSuctioning Event

Clearing of secretion (Suctioning)Clearing of secretion (Suctioning)- Most common procedure done in ICU- Most common procedure done in ICU- Should be done when needed, not on time - Should be done when needed, not on time basisbasisSuction cathetersSuction catheters Should be made of clear materialsShould be made of clear materials Size not greater than half the diameter of ETTSize not greater than half the diameter of ETT Should be longer than ETTShould be longer than ETT

Suctioning Event (Cont’d)Suctioning Event (Cont’d)

Suction techniquesSuction techniques• Open Open

Disconnecting the patient from the Disconnecting the patient from the ventilatorsventilators

• Closed Closed Allow the catheter to suck without Allow the catheter to suck without

disconnecting from ventilatorsdisconnecting from ventilators

Suctioning Event (Cont’d)Suctioning Event (Cont’d)

ComplicationsComplications• Cardiac arrhythmias Cardiac arrhythmias • Vagal stimulationVagal stimulation• Cardiac arrestCardiac arrest• Mucosal trauma Mucosal trauma • AtelectasisAtelectasis• Hypoxemia Hypoxemia • Infection Infection • Raised Intracranial tensionRaised Intracranial tension

Nutritional supportNutritional support

• Nutritional support is very important in Nutritional support is very important in ventilator patientsventilator patients

• Acute loss of 30-40% Body weight is lethalAcute loss of 30-40% Body weight is lethal• Poor nutrition leads to ventilator muscle Poor nutrition leads to ventilator muscle weakness and delay Weaningweakness and delay Weaning

Other General Care – Other General Care – Mobilization of PatientMobilization of Patient• Seven days bed rest leads to loss of muscle Seven days bed rest leads to loss of muscle

bulk up to 30%bulk up to 30%• Patient may require active, assisted Patient may require active, assisted

or passive movementor passive movement• The joints should be maintained and protected The joints should be maintained and protected

in neutral positionin neutral position

Other General Care – Other General Care – Pressure soresPressure sores

- Dependent areas of immobile patient- Dependent areas of immobile patient- Tissues over the bony prominence- Tissues over the bony prominence- Trauma, Diabetics Burn patients – High Risk- Trauma, Diabetics Burn patients – High Risk

Preventive measuresPreventive measures• Regular turning and repositioning every 2-4 hoursRegular turning and repositioning every 2-4 hours• Special mattress and beds should be used to Special mattress and beds should be used to

relieve pressure over susceptible areasrelieve pressure over susceptible areas• Regular inspection of skin integrityRegular inspection of skin integrity• Early nutritional supportEarly nutritional support

Other general care –Other general care –Eyes and mouth careEyes and mouth care

- Commonest problems are Dry eyes and - Commonest problems are Dry eyes and Exposure keratopathyExposure keratopathy- Protective mechanisms are lost- Protective mechanisms are lost- Decreased tear production- Decreased tear production- Decreased resistance to infection- Decreased resistance to infection

PreventionPreventionArtificial eye drops, hydrogel padsArtificial eye drops, hydrogel pads

Other general care - Other general care - Oral hygieneOral hygiene

Oral Ulcers and Infection are commonOral Ulcers and Infection are commonDecreased Oral fluid intakeDecreased Oral fluid intakeMucosal DehydrationMucosal DehydrationDecreased saliva productionDecreased saliva productionPresence of Orotracheal tubePresence of Orotracheal tube

Prevention of InfectionPrevention of Infection

ICU patients are 4 times more prone to ICU patients are 4 times more prone to develop to nosocomial infectionsdevelop to nosocomial infections

Common sites Common sites LungLungCatheter sitesCatheter sitesUrinary tractsUrinary tractsWoundWound

Prevention of InfectionPrevention of Infection (Cont’d) (Cont’d)

• As many as 40% of infections are transmitted As many as 40% of infections are transmitted by the hands of Hospital staffby the hands of Hospital staff

• Most important preventive measure against the Most important preventive measure against the spread of infection is Hand Washingspread of infection is Hand Washing

Infections can be decreased byInfections can be decreased by Using Antibiotics, Isolation techniquesUsing Antibiotics, Isolation techniquesUse of Disposable components-Use of Disposable components-

ETT, Catheters, Ventilator tubing and fittingsETT, Catheters, Ventilator tubing and fittings

ALARMSALARMS

• Look from whereLook from where• Do not switch alarm off until cause of Do not switch alarm off until cause of

alarm trigger is identified and correctedalarm trigger is identified and corrected

Discontinuing Mechanical VentilationDiscontinuing Mechanical Ventilation

• DeathDeath• WeaningWeaning

– Up to 25% of patients have Respiratory Up to 25% of patients have Respiratory distress severe enough to require distress severe enough to require reinstitution of ventilator.reinstitution of ventilator.

• ExtubationExtubation– 10 - 20 % of Extubated patients who were 10 - 20 % of Extubated patients who were

successfully weaned require reintubation.successfully weaned require reintubation.

THE WEAN (Liberation from MV)THE WEAN (Liberation from MV)

Weaning is the gradual withdrawal fromWeaning is the gradual withdrawal fromMechanical Ventilation.Mechanical Ventilation.• Hemodynamically stableHemodynamically stable• Correction of underlying lung diseaseCorrection of underlying lung disease• Correction of acid-base/electrolyte disordersCorrection of acid-base/electrolyte disorders• Adequate nutritionAdequate nutrition• Mentally alertMentally alert• Avoidance of sedationAvoidance of sedation

THE WEAN (Cont’d)THE WEAN (Cont’d)

Techniques to Wean!! Techniques to Wean!! • SIMV WeanSIMV Wean• PS WeanPS Wean• T- Piece TrialT- Piece Trial

TroubleshootingTroubleshooting

Is it working or not?Is it working or not?– Look at the patient !!Look at the patient !!– Listen to the patient !!Listen to the patient !!– SaOSaO22, ABG, EtCO, ABG, EtCO22

– Chest X rayChest X ray– Look at the Ventilator (PIP; Expired TV; Look at the Ventilator (PIP; Expired TV;

Alarms)Alarms)

TroubleshootingTroubleshooting (Cont’d) (Cont’d)

• When in doubt, DISCONNECT THE PATIENT When in doubt, DISCONNECT THE PATIENT FROM THE VENTILATOR, and begin AMBU Bag FROM THE VENTILATOR, and begin AMBU Bag Ventilation.Ventilation.

• Ensure you are bagging with 100% O2.Ensure you are bagging with 100% O2.• This eliminates the Ventilator circuit as the This eliminates the Ventilator circuit as the

source of the problem.source of the problem.• Bagging by hand can also help you gauge Bagging by hand can also help you gauge

patient’s compliancepatient’s compliance

TroubleshootingTroubleshooting (Cont’d) (Cont’d)

• Airway firstAirway first!!!!!!

• Breathing nextBreathing next!!!! • Circulation!Circulation!

COMPLICATIONSCOMPLICATIONS

• Ventilator Induced Lung InjuryVentilator Induced Lung Injury– Oxygen toxicityOxygen toxicity– Barotraumas / VolutraumasBarotraumas / Volutraumas

•Peak PressurePeak Pressure•Plateau PressurePlateau Pressure•Shear Injury (Tidal Volume)Shear Injury (Tidal Volume)•PEEPPEEP

COMPLICATIONSCOMPLICATIONS (Cont’d) (Cont’d)

• Cardiovascular ComplicationsCardiovascular Complications– Impaired venous return to RAImpaired venous return to RA– Bowing of the Interventricular SeptumBowing of the Interventricular Septum– Decreased left sided afterload (good)Decreased left sided afterload (good)– Altered right sided afterloadAltered right sided afterload

• Sum Effect…..Sum Effect….. Decreased Cardiac Output Decreased Cardiac Output (usually, not always and often we don’t even (usually, not always and often we don’t even notice)notice)

COMPLICATIONSCOMPLICATIONS (Cont’d) (Cont’d)

• Other ComplicationsOther Complications– Ventilator Associated Pneumonia (VAP)Ventilator Associated Pneumonia (VAP)– SinusitisSinusitis– SedationSedation– Risks from associated devices Risks from associated devices

(Central Lines, Arterial Lines)(Central Lines, Arterial Lines)– Unplanned ExtubationUnplanned Extubation

Related TerminologiesRelated Terminologies

• Auto PEEPAuto PEEP

• Alveolar RecruitmentAlveolar Recruitment

• Prone VentilationProne Ventilation

Please Do Remember!!Please Do Remember!! WHEN IN ANY DOUBT ABOUTWHEN IN ANY DOUBT ABOUT

THE ADEQUACY OF THE ADEQUACY OF MECHANICAL VENTILATION...MECHANICAL VENTILATION...

MANUALLY VENTILATE THE MANUALLY VENTILATE THE PATIENT WITH AN AMBU BAG,PATIENT WITH AN AMBU BAG, WITH THE AVAILABLE WITH THE AVAILABLE MAXIMUM OMAXIMUM O22

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DOUBTSDOUBTS????