Week 3 Ventilation of the Critically Ill Transfer Simon Giles

8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles

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Simon Giles

Ventilation of the Critically ill

Simon GilesConsultant Nurse in Critical CareHeart of England NHS Trust



Simon Giles



Simon Giles

Objectives

Review the Basic Anatomy & Physiology of Respiratory System

Understand reasons Artificial Ventilation

Review modes & specific strategies usedin ventilating the Critically Ill

Discuss specific conditions in the CriticallyIll patient

Be aware of possible complications



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Basic Anatomy

Upper Airway

humidifies inhaled gases

site of most resistance to airflow

Lower Airway

conducting airways (anatomic dead space)

respiratory bronchioles and alveoli (gasexchange)



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Basic Physiology

http://www.biology.eku.edu/RITCHISO/301notes6.htm


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Physiology of Respiration

Ventilation

Movement of air between the alveoli andatmosphere

Diffusion

Movement of CO2 and O2 between alveoli andcapillaries

Transport

Movement of O2 from the alveoli to the cells

Movement of CO2 from the cells to the alveoli



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Abnormal Gas

Exchange Hypoxemia can bedue to:

hypoventilation

V/Q mismatch

shunt

diffusion

impairments

Hypercarbia can bedue to:

hypoventilation

V/Q mismatch



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VOELAR

GALILEO

RAPHAEL

HAMILTON G5

ventiPAC 200D

TRANSFER VENTILATOR



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Mechanical Ventilation

Ventilators deliver gas to the lungsusing positive pressure at a

certain rate . The amount of gasdelivered can be limited by time,pressure or volume. The duration

can be cycled by time, pressureor flow.



Surgical: Post-operative support, supporting other organs failure.

Respiratory centre depression:• Head injury raised intracranial pressure.• Hypercapnia.• Drug toxicity.• Meningitis, tumours, epilepsy.

Lung Disease:

• ARDS (acute respiratory distress syndrome), pneumonia, acute asthma, COPD (chronicobstructive pulmonary disease).• Aspiration, drowning, smoke inhalation, chemical attack e.g. anthrax, biological e.g. bird

flu, legionella.

Circulatory: Cardiac arrest, pulmonary oedema, shock, sepsis.

Trauma: Cervical cord trauma above C4, neck fractures, facial injury, major blood loss.

Neuromuscular disorders: Guillian-Barre, myasthenia gravis, poliomyelitis.

Chest wall disorders: traumatic flail segment, mesothelioma.

Other factors:• Poor nutrition leading to muscle weakness.• Abdominal distension/pain which squashes the diaphragm .• Low GCS ( Glasgow Coma Scale).



• The most commonly used in the ITU setting an ET (Endo-Tracheal) tube.

• For patient on a ventilator for longer than 7-10 days a tracheotomy is performed, as thishelps with the patients weaning, its more comfortable for the patient and less dead spacereducing the work of breathing for the patient, and easier for the patient to communicate

(Orlando, 2007c).

• For short term ventilation for an operation or in an emergency, LMA (Laryngeal MaskAirway) may be used. (Leach,et al, 2004).

• For non invasive ventilation a tight fitting face mask is used (Leach,et al, 2004).

Video on Endotracheal Ventilation , (Bmedinago, May 2007) <http://uk.youtube.com/watch?v=cLL6XwhFEFQ>

http://uk.youtube.com/watch?v=cLL6XwhFEFQ

http://uk.youtube.com/watch?v=cLL6XwhFEFQ



PRESSURE BASED

• “In a pressure-cycled ventilator, once a pre-setpressure is reached within the ventilator, thebreath is terminated and positive pressure cyclecompleted.” (Cited from Wikimedia, 2008)

VOLUME BASED

• “In a volume-cycled ventilator the ventilator delivers a pre-setvolume of gas with each breath to the patient as soon as thespecified volume of breath is delivered, the positive pressurecycle is completed.” (Cited from Wikimedia, 2008)

P-CMV (Pressure Controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t

support any spontaneous efforts(Wikimedia, 2008).(S) CMV (Synchronised volume controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t support any

spontaneous efforts (Hamilton, 2007).

P-SIMV (Pressure controlled SynchronisedIntermittent Mandatory Ventilation).• Allows the patient to breathe synchronising with

them providing some support l imiting thepressure(Wikimedia, 2008).

SIMV (Synchronised Intermittent Mandatory Ventilation)• Allows the patient to breathe providing some support but

delivers a set volume (Wikimedia, 2008)

PSV/SPONT(Pressure Support Ventilation).• No Set Rate used with PEEP and a set pressure ,

supporting the patients own respiratory pattern(Orlando, 2007c).

ADAPTIVE INTELIGENT MODES

• These modes provide the advantages of both pressure based

modes whilst still offering a volume guarantee• Allows spontaneous breathing adjusting the support required to

reach the targeted volume(Hamilton, 2007).

BI-PHASIC MODES

• These modes allow the patient to breathspontaneously at any time, even when the ventilatoris delivering a mandatory breath. (Hamilton, 2007).

APV (cmv) (Adaptive Pressure Ventilation with pressurecontrolled mandatory ventilation).• Targets a specified volume to be delivered.• Automatic regulation in inspired pressure and flow (Hamilton,

2007).

Duo PAP (Dual Positive Airway Pressure).

• You have to set the Rate and high airway pressure.• All other advantages same as APRV (Hamilton,

2007).

APV (simv) (Adaptive Pressure Ventilation with synchronised

intermittent mandatory ventilation).• Same as above.

APRV(Airway Pressure Release Ventilation).• The ventilator cycles from high CPAP to low CPAP

(high lung pressure/volume to low lungpressure/volume).

• Allows the patient to breathe supported or unsupported .

• Used usually for patients with severe ARDS

(Neligan, 2006)

ASV (Adaptive Support Ventilation).• Closed loop control ventilation system• ASV responds to and adapt to the patients own spontaneous

breathing pattern.• Reduces the work of breathing.• Patients height measured to calculate ideal body weight.• Reduces weaning time (Hamilton, 2006a).

PRESSURE BASED

• “In a pressure-cycled ventilator, once a pre-setpressure is reached within the ventilator, thebreath is terminated and positive pressure cyclecompleted.” (Cited from Wikimedia, 2008)

VOLUME BASED

• “In a volume-cycled ventilator the ventilator delivers a pre-setvolume of gas with each breath to the patient as soon as thespecified volume of breath is delivered, the positive pressurecycle is completed.” (Cited from Wikimedia, 2008)

P-CMV (Pressure Controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t

support any spontaneous efforts(Wikimedia, 2008).

(S) CMV (Synchronised volume controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t support any

spontaneous efforts (Hamilton, 2007).

P-SIMV (Pressure controlled SynchronisedIntermittent Mandatory Ventilation).• Allows the patient to breathe synchronising with

them providing some support l imiting thepressure(Wikimedia, 2008).

SIMV (Synchronised Intermittent Mandatory Ventilation)• Allows the patient to breathe providing some support but

delivers a set volume (Wikimedia, 2008)

PSV/SPONT(Pressure Support Ventilation).• No Set Rate used with PEEP and a set pressure ,

supporting the patients own respiratory pattern(Orlando, 2007c).

ADAPTIVE INTELIGENT MODES

• These modes provide the advantages of both pressure based

modes whilst still offering a volume guarantee• Allows spontaneous breathing adjusting the support required to

reach the targeted volume(Hamilton, 2007).

BI-PHASIC MODES

• These modes allow the patient to breathspontaneously at any time, even when the ventilatoris delivering a mandatory breath. (Hamilton, 2007).

APV (cmv) (Adaptive Pressure Ventilation with pressurecontrolled mandatory ventilation).• Targets a specified volume to be delivered.• Automatic regulation in inspired pressure and flow (Hamilton,

2007).

Duo PAP (Dual Positive Airway Pressure).

• You have to set the Rate and high airway pressure.• All other advantages same as APRV (Hamilton,

2007).

APV (simv) (Adaptive Pressure Ventilation with synchronised

intermittent mandatory ventilation).• Same as above.

APRV(Airway Pressure Release Ventilation).• The ventilator cycles from high CPAP to low CPAP

(high lung pressure/volume to low lungpressure/volume).

• Allows the patient to breathe supported or unsupported .

• Used usually for patients with severe ARDS

(Neligan, 2006)

ASV (Adaptive Support Ventilation).• Closed loop control ventilation system• ASV responds to and adapt to the patients own spontaneous

breathing pattern.• Reduces the work of breathing.• Patients height measured to calculate ideal body weight.• Reduces weaning time (Hamilton, 2006a).



Simon Giles

SIMV, volume-limited

Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB,

Scmidt GA, & Wood LDH(eds.): Principles of Critical Care



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Pressure vs. Volume

Pressure Limited

Control FiO2 and MAP(oxygenation)

Still can influenceventilation somewhat(respiratory rate, PAP)

Decelerating flow

pattern (lower PIP forsame TV)

Volume Limited

Control minuteventilation

Still can influenceoxygenationsomewhat (FiO2,

PEEP, I-time) Square wave flow

pattern



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Pressure vs. Volume

Pressure Pitfalls tidal volume by change

suddenly as patient’s

compliance changes this can lead to

hypoventilation oroverexpansion of thelung

if ETT is obstructedacutely, delivered tidalvolume will decrease

Volume Vitriol

no limit per se on PIP(usually vent will haveupper pressure limit)

square wave(constant)flow pattern results inhigher PIP for same tidal

volume as compared toPressure modes



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Trigger

How does the vent know when to give abreath? - “Trigger”

patient effort

elapsed time

The patient’s effort can be “sensed” as

a change in pressure or a change in

flow (in the circuit)



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Need a hand??

Pressure Support

“Triggering” vent requires certain amount of work by patient

Can decrease work of breathing by providingflow during inspiration for patient triggeredbreaths

Can be given with spontaneous breaths inIMV modes or as stand alone mode withoutset rate

Flow-cycled



TERMINOLOGY OFVENTILATION

FREQUENCY : BREATH RATE

TV : TIDAL VOLUME IN SINGLE BREATH

MV : MINUTE VOLUME (TV x BR)

I:E RATIO : INSPIRATORY/EXPIRATORY RATIO PEAK PRESSURE : HIGHEST PRESSURE ON

INSPIRATION

PEEP : POSITVE END EXPIRATORY PRESSURE

CPAP : CONTIUOUS POSITIVE AIRWAY PRESSURE FIO2 : FRACTIONAL INSPIRED OXYGEN



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Initial Settings

Pressure Limited

FiO2

Rate I-time or I:E ratio

PEEP

PIP or PAP

Volume Limited

FiO2

Rate I-time or I:E ratio

PEEP

Tidal VolumeThese choices are with time - cycled ventilators.

Flow cycled vents are available but not commonly

used in pediatrics.



TROUBLE SHOOTING : LOWOXYGENATION

INCREASE FIO2

CHECK TV

SUCTION PATIENT IF NEEDED INCREASE PEEP

CHANGE I:E RATIO

CHECK SEDATION



TROUBLE SHOOTING: HIGHCARBON DIOXIDE

INCREASE RESPIRATORY RATE

CHANGE I:E RATIO

CHECK SEDATION CHECK TIDAL VOLUMES

CHECK MINUTE VOLUMES



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Except...

Is it really that simple ?

Increasing PEEP can increase dead

space, decrease cardiac output, increase V/Q mismatch

Increasing the respiratory rate can leadto dynamic hyperinflation (aka auto-PEEP), resulting in worseningoxygenation and ventilation



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Troubleshooting

Is it working ?

Look at the patient !!

Listen to the patient !! Pulse Ox, ABG, EtCO2

Chest X ray Look at the vent (PIP; expired TV;

alarms)



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Troubleshooting

When in doubt, DISCONNECT THEPATIENT FROM THE VENT, and begin bagventilation.

Ensure you are bagging with 100% O2.

This eliminates the vent circuit as thesource of the problem.

Bagging by hand can also help you gaugepatient’s compliance



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Troubleshooting Airway first: is the tube still in? (may need

DL/EtCO2 to confirm) Is it patent? Is it in theright position?

Breathing next: is the chest rising? Breathsounds present and equal? Changes in exam?

Atelectasis, bronchospasm, pneumothorax,

pneumonia? (Consider needle thoracentesis) Circulation: shock? Sepsis?



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Troubleshooting

Well, it isn’t working….. Right settings ? Right Mode ?

Does the vent need to do more work ?

Patient unable to do so

Underlying process worsening (or new problem?)

Air leaks?

Does the patient need to be more sedated ? Does the patient need to be extubated ?

Vent is only human…..(is it working ?)



Simon Giles

Troubleshooting

Patient - Ventilator Interaction

Vent must recognize patient’s

respiratory efforts (trigger) Vent must be able to meet patient’s

demands (response)

Vent must not interfere with patient’s

efforts (synchrony)



Simon Giles

Troubleshooting

Improving Ventilation and/or Oxygenation can increase respiratory rate (or decrease rate

if air trapping is an issue)

can increase tidal volume/PAP to increasetidal volume

can increase PEEP to help recruit collapsedareas

can increase pressure support and/ordecrease sedation to improve patient’sspontaneous effort



Difficult Clinical conditions to

Ventilate

ARDS

Rule of 1/3

Thoracic Surgical BPF

One lung

Complex Pneumonia



• The three pictures of the alveoli show the differentphases they go through in an ARDS patient.

• It is beyond the scope of this teaching tool to go intoin-depth anatomy and physiology, but it is hoped thatthis gives the reader a brief glimpse, leading tofurther reading, improving knowledge.

• The author found these very useful in Understanding

ARDS.

FIBROTIC/RECOVERY PHASE.

HEALTHY ALVEOLI.

INJUREDALVEOLI OF

ARDSPATIENT DURING

ACUTE PHASE.

Pictures from Module 2 ARDS lectureGiven by: Nurse Consultant, Simon Gi les.(October, 2007).



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Lowered Expectations

Permissive Hypercapnia accept higher PaCO2s in exchange for limiting

peak airway pressures

can titrate pH as desired with sodiumbicarbonate or other buffer

Permissive Hypoxemia accept PaO2 of 55-65; SaO2 88-90% in

exchange for limiting FiO2 (<.60) and PEEP can maintain oxygen content by keeping

hematocrit > 30%



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Complications

Ventilator Induced Lung Injury

Oxygen toxicity

Barotrauma / VolutraumaPeak Pressure

Plateau Pressure

Shear Injury (tidal volume)

PEEP



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Complications

Cardiovascular Complications Impaired venous return to RH

Bowing of the Interventricular Septum Decreased left sided afterload (good)

Altered right sided afterload

Sum Effect…..decreased cardiac output(usually, not always and often we don’t evennotice)



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Complications

Other Complications

Ventilator Associated Pneumonia

Sinusitis

Sedation

Risks from associated devices (CVLs, A-lines)

Unplanned Extubation



Long Term Complications

Airway Stenosis – ETT Cuff / Tracheostomy

Mouth / lips - erosions

Lung Fibrosis (ARDS)

General Critical Illness ( neuropathy )

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To ‘Wind’ Up

Whistle top tour of A&P

Ventilation of the Critically Ill is OftenComplex

Modern Machines have many differentmodes for difficult ventilation

Positive Pressure Ventilation is harmful tolung tissue and does not cure patient

Week 3 Ventilation of the Critically Ill Transfer Simon Giles

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