mv complications

7/30/2019 Mv Complications

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Adverse Effects and Complications

of Mechanical Ventilation

Ibrahim Al-Sanouri,MD, FCCP, FAAAAI


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4 major concepts

` Know thy patient

` Know thy ventilator

` Put the ventilator between you and the patient` Alive ventilated patients

` The illness caused the need for mechanical ventilation


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MVcomplications

MechanicalsBiophysical

InflammatoryCytokines

Biochemical

MedicationModes

Disease


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Unable to Open Mouth

Trismus

Small mouth

Peri-oral scarring

Fascial swealling

Unable to insert laryngoscope

Short neckLarge chest

Prominent upper incisors

Small mandible

Edema

Unable to see glottis

Fixed position of the head

Small jaw

Anterior larynx

Obstructed by blood or vomit

Unable to pass tube into

trachea

Fixed Unrecognizable glottis

Too small glottis or sub-

glottic diameter

Trauma

Endobronchial

intubation

Esophageal intubation

Severe hypoxiaSevere hypotension

Death

Environment

No skilled help

No specialized equipments

Missing of defective

equipmentPoor positioning

Mechanical


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Maxillary Sinus and Middle Ear Effusion

` Maxillary effusion

` 20% in patients intubated for > 7 days and oral intubation or

oral gastric tubes` 47% when the gastric tube is placed nasally

` 95%

` Secondarily infected maxillary effusion (45-71% ofeffusions)

` Middle ear effusion (29%) with 22% of them become

infected` Hearing impairment that may contributes to the

confusion and delirium ion elderly population


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Pharyngo-laryngeal Dysfunction

` Post-extubation discomfort (40% regardless of theduration)

` Hoarsness

` 52% in short-term intubation

` 70% in patients with prolonged intubation

` Slowing of the reflex swallowing mechanism and risk ofaspiration

` 15.8% of patients who were intubated more than 4 days didnot have a gag refelex

` Silent aspiration:` 20% in young population

` 36% in older population


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Laryngeal Injuries

` Some degree of glottic injury is seen in 94% of patients

intubated for 4 days or longer

` Erosive ulcers of vocal cords (posterior commisure)` Swelling and edema of the vocal cords

` Granulomas (7% in patients intubated for 4 days or more)


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Tracheal Injuries

` Cuff pressure tracheal damage: tracheal ulceration, edema

and submucosal hemmorrhage

` Tracheal dilatation` Tracheal stenosis:

` At he site of the cuff (50%)

` At the site of the tracheostomy (35%)

` Unclear (15%)


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Cardiovascular Effects of

Mechanical Ventilation


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Decreased pressure Gradient for venous

return and decrease RV preload

PPV

Decreased CO due to decreased RV fi ll ing

Volume due to decreased venous

return


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-2 mm Hg

3 mm Hg

5 mm Hg

6 mm Hg

8 mm Hg

2 mm Hg

Effect of Positive Pressure Ventilation on

Right Atrial Distension

PPV

Decreased CO due to decreased RV fi ll ingVolume due to decrease RA compliance


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Spontaneous Ventilation

0

5

3

-3

120

0

10


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Spontaneous Ventilation

0

5

3

-3

110

0

8


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Hypotension following MV


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Cyclic BP effects is related to Volume

status

Ventilation on sick individual


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PPV could increase CO and BP

` Ventricular interdependence: decrease CO during

spontaneous breathing due to : increase RV filling volume

with shifting the intraventricular septum causing mechanicimpedance for LV decreasing its compliance causing

decrease CO and BP

` In this situation PEEP will be beneficial` Increase in transmural pressure of the great arteries in

the thorax, Transmural pressure represent how easy the

blood vessels could distend once accommodating for thestroke volume to enter


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Cyclic changes in Gas exchange and partial

pressures


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Hemodynamic effects of mechanical insufflations

.

End of inspiration

Maximum of

SBP, PP, Aortic velocity

End of inspiration

Minimum of

SBP, PP, Aortic velocity

Inc.

LV ejection

Dec.

LV ejection


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Effect of Mechanical Ventilation on

Pulmonary Vascular Resistance


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Effect of Changing Lung Volume on

Pulmonary Vascular Resistance

Pulm

onaryvascularResistance

Lung Volume

Total pulmonary vascular resistance

Intra-alveolar vaso-compression

Hypoxic vasoconstriction


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Effect of Lung Volume on RV afterload

` No effect in Normal indiidul with PEEP less than 10

cmH2o

` Major effect In patients with dynamic hyperinflaiton suchas asthmatic and COPD, and in pre-existing pumonary

hypertension

` Samll changes in PVR can cause considerablehaemodynamic comproise secondery toacute increase in

PVR

` Avoid gas traping in these patient

Know the patient, Know


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Alveolar pressure and Gas exchange


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Pleural pressure

Venous Return

V/Q Matching

LV afterload

Work of Breathing

Fully

Spontaneous

Partial

Ventilator

support

Fully

Controlled

Effects of PPV on hemodynamic

B d di d i i l


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Bradycardia and intra-arteriolar

vasodilatation


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Biochemical effect

of Mechanical VentilationInflammatory cytokines


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Inflammatory Biochemical injury

Local and systemic

Inflammation cascade


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Micro vascular, Alveolar Fracture

Hotchkiss et allCritical care Med, 2002

Prot for Gas and Bacteria


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Biochemical effect of MV

Pro- Inflammatory Cytokines during PPV


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Oxygen Toxicity


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` Tracheobronchitis

` Absorpetive atelctasis

` Hypercarbia` Diffuse alveolar damage


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Intrinsic PEEP, Auto PEEP


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Gastrointestinal Effects of



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GI Effects of MV


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Esophagus, Stomach and Small Intestine

` Erosive esophagitis (30-50% of patients ventilated >48

hours)

`

NG tube` Poor lower esophageal sphincter tone and reflux

` Opiates and adrenergic agonists

`

Duodenogastroesophageal reflux through the action of trypsin` Upper gastrointestinal hemorrhage:

` Stress

` Decreased gastric mucosal protection secondary to a fall insplanchnic blood flow

` Decreased motility of stomach and small intestine


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Liver and Gallbladder

` Reduction in portal venous flow secondary to the fall in

cardiac output

`

Increased hepatic arterial flow hepatic arterial bufferresponse

` Normal total hepatic perfusion

` Hepatic engorgement` Venous ischemia and elevation of serum transaminases

and hyperbilirubinemia

` Reduction in drug clearance secondary to reduction of

hepatic blood flow


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Large Bowel

` Constipation

` Abdominal distension


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GI Effects of PPV


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Renal Functions during



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Neurological Functions during



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Acute Effects

` Vasoconstriction secondary to hypercapnia

` Decreased intra-cerebral blood volume and intracranial

pressure` PEEP reduces cerebral perfusion pressure by decreasing

venous return and increasing intracranial pressure

` 20-25% of is transmitted to the central venous pressure in anormal compliant lung

` >20% is transmitted in patients with decreased lung

compliance


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8 10 12 14 16 18 20 22 0 2 4 6 8

Stage 1

Stage 2

Stage 3

Stage 4

REM

Normal Sleep Pattern

H f P ti t M h i l


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8 10 12 14 16 18 20 22 0 2 4 6 8

Stage 1

Stage 2

Stage 3

Stage 4

REM

Hyponogram for a Patient on Mechanical

Ventilation


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0

100

200

300

100

Stage 1

Stage 2

Stage 3

Stage 4

REM

NonREM

Age 40 Age 40 MV

SleepTim

e(minutes)

M h i b hi h h i l


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Mechanisms by which mechanical

Ventilation Disrupt Sleep

` Noise disruption` Ventilator alarm:

` inappropriate threshold

` Delayed alarm inactivation` Humidifier alarms

` Disruption by nursing interventions` Airway suction

` Nebulizer delivery` Ventilation-related pharmacological disruption

` Benzodiazepines (REM, deep NREM)

` Oipoids (REM, deep NREM)

` Neuromuscular blocking drugs

` Ventilator mode` Pressure support ventilation


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Asynchrony with the patient


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Asynchrony with the ventiaitor

` Fighting the ventilators

` Inconsistent tidal volume

` Increase work of breathing

` Barotraumas and thoracic air leak` Insufficient gas exchange

` Disturbances in the cerebral blood flow


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Ventilation complications

Mode specific

CMV

CMV

IPPVIPPV

SIMV

SIMV

MMVMMV

BIPAPBIPAP

CPAP

CPAP

SPONT

SPONT

PCVPCV

VCVVCV

APRVAPRV

PLVPLVPSPS

ASBASB

ILV

PRVCPRVC

VAPSVAPS

PAV

PAV

What About New Modes?

Auto ModeAuto Mode

AutoFlowAutoFlow

PPSPPS

VSVS

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