Non-Pulmonary Complications of Mechanical Ventilation

Complications of Mechanical Ventilation

• Complications related to Intubation• Mechanical complications related to presence

of ETT• Pulmonary complications• Cardiovascular complications• Biomedical complications• Neurological complications• Other complications

Four major concepts

• Know the patient• Know the ventilator• Put the ventilator between you and the patient• Alive ill patients

MV complications

MechanicalsBiophysical

Inflammatory Cytokines

Biochemical

MedicationModes

Disease

COMPLICATIONS RELATED TO AIRWAYS

CompetenceConfidence

Unable to Open Mouth• Trismus• Small mouth• Peri-oral scarring• Fascial swealling

Unable to insert laryngoscope• Short neck• Large 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 diamete

Vulnerability to complications• Fixed Full stocmach• Hypovolemia• Hypotension• Hypoxemia• Hypercarbia• Agitation• Age and sex

• Trauma• Endobronchial

intubation• Esophageal

intubation• Severe hypoxia• Severe

hypotension• Death

Environment• No skilled help• No specialized equipments• Missing of defective

equipment• Poor positioning

Difficult Intubation

Injuries to Face, Lips and Oro-pharynx

• Trauma to the lips and cheeks from tube ties• Peri-oral herpes• Injuries to the tongue especially if entrapped

between the endotracheal tube and the lower teeth

• Pressure ulcers to the palate and oropharynx

Skin Avulsion

Tongue Injury

Lip Injury Periorbital herpes

Maxillary Sinus and Middle Ear Effusion

• Maxillary effusion – 20% in patients intubated for > 7 days.– 47% when the gastric tube is placed nasally– 95%

• Secondarily infected maxillary effusion (45-71% of effusions)

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

• Hearing impairment that may contributes to the confusion and delirium in elderly population

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 commissures)

• Swelling and edema of the vocal cords• Granulomas (7% in patients intubated for 4

days or more)

Vocal Cords Ulcers Granulomas

Vocal Cord Hematoma

Vocal Cord Edema

Pharyngo-laryngeal Dysfunction

• Post-extubation discomfort (40% regardless of the duration)

• Hoarsness : edema, injury, disarticulate– 52% in short-term intubation– 70% in patients with prolonged intubation

• Slowing of the reflex swallowing mechanism and risk of aspiration– 15.8% of patients who were intubated more than 4 days did

not have a gag reflex• Silent aspiration: Ventilator Associated Pneumonia

– 20% in young population– 36% in older population

Tracheal Injuries• Cuff pressure related tracheal mucosa ischemia• Cuff pressure tracheal damage: tracheal ulceration, edema and

sub-mucosal hemorrhage• Tracheal dilatation: tracheomalacia• Tracheal stenosis:

– At the site of the cuff (50%)– At the site of the tracheostomy (35%)– Unclear (15%)

Tracheal Stenosis Glottic Stenosis

Granuloma and Ulceration Tracheomalacia

Unplanned Extubation

• Self extubation (8%) and accidental extubation (1%)

• Longer ICU and hospital stay• Increased ICU and hospital mortality

CARDIOVASCULAR COMPLICATIONS OF MECHANICAL VENTILATION

Biomechanical effect

Exp InspCV

PPr

essu

re (m

mHg

)

Extra

thor

acic

vein

s

Righ

t atri

um

Exp Insp

CVP

Pres

sure

(mm

Hg)

Extra

thor

acic

vein

s

Righ

t atri

um

Decreased Cardiac Output.Decreased Pressure Gradient for venous return and decrease RV preload

PPVDecreased CO due to decreased RV filling

Volume due to decreased venousreturn

-2 mm Hg

3 mm Hg

5 mm Hg

6 mm Hg

8 mm Hg

2 mm Hg

Decreased Cardiac OutputDecreased Right Atrial Distension

PPVDecreased CO due to decreased RV fillingVolume due to decrease RA compliance

Decreased BPPPV vs. Spontaneous Ventilation

0

5

3

-3

120

0

10

Decreased BPPPV VS. Spontaneous Ventilation

0

5

3

-3

110

0

8

Hypotension following MV

PPV increase CO and BP

• Ventricular interdependence: decrease CO during spontaneous breathing due to : increase RV filling volume with shifting the intra ventricular septum causing mechanic impedance for LV decreasing its compliance causing decrease CO and BP

• PPV improve the dynamic shape of the septum providing better LV compliance, better preload and thus better Stroke Volume and BP.

• Increase in Trans mural pressure of the great arteries in the thorax.

Cyclic BP effects is related to Volume status

Ventilation on sick individual

Cyclic changes in Gas exchange and partial pressures

Effect of Changing Lung Volume on Pulmonary Vascular Resistance

Pulm

onar

y va

scul

ar R

esist

ance

Lung Volume

Total pulmonary vascular resistance

Intra-alveolar vaso-compressionHypoxic vasoconstriction

RV TLCFRC

Hemodynamic effects of mechanical Insuflation

.

End of inspirationMaximum of

SBP, PP, Aortic velocity

End of inspirationMinimum of

SBP, PP, Aortic velocity

Inc.LV ejection

Dec.LV ejection

Effect of Lung Volume

• No effect in Normal individual with PEEP less than 10 cmH2o

• Major effect in patients with Dynamic Hyperinflation such as asthmatic and COPD, and in pre-existing pulmonary hypertension

• Small changes in PVR can cause considerable hemodynamic compromise secondary to acute increase in PVR

• Avoid gas trapping in these patient

Know the patient, Know the ventilator

Alveolar pressure and Gas exchange

Dead Space

PaO2

Oxygen Transport

Pleural pressure

Venous Return

V/Q Matching

LV afterload

Work of Breathing

Fully Spontaneous

PartialVentilatorsupport

Fully Controlled

Effects of PPV on hemodynamicM

agni

tude

of E

ffect

Bradycardia and intra-arteriolar vasodilatation

Reflex Arrhythmias, Bradycardia

Intra arteriolar Vasodilatation

Effect of Preload on Cardiac Output

Left Ventricular Preload

Card

iac

Outp

utNormal cardiac function

Congestive heart failure

BIOCHEMICAL EFFECTOF MECHANICAL VENTILATION

Systemic inflammatory effect

Inflammatory Biochemical injury

Local and systemic Inflammation cascade

Micro vascular, Alveolar Fracture

Hotchkiss et allCritical care Med, 2002

Prot for Gas and Bacteria

Biochemical effect of MV

Pro- Inflammatory Cytokines during PPV

NEUROLOGICAL FUNCTIONS DURING MECHANICAL VENTILATION

Psychogenic effect

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 a normal compliant lung– >20% is transmitted in patients with decreased

lung compliance

0

100

200

300

100

Stage 1

Stage 2

Stage 3

Stage 4REM

Non REM

Age 40

Age 40

MV

Slee

p Ti

me

(min

utes

)

8 10

12

14

16

18

20

22

0 2 4 6 8

Stage 1Stage 2

Stage 3Stage 4

REM

Normal Sleep Pattern

8 10

12

14

16

18

20

22

0 2 4 6 8

Stage 1Stage 2

Stage 3Stage 4

REM

Hyponogram for a Patient on Mechanical Ventilation

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

GASTROINTESTINAL EFFECTS OF MECHANICAL VENTILATION

Systemic inflammatory and low perfusion effects

GI Effects of PPV

GI Effects of MV

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 in

splanchnic blood flow• Decreased motility of stomach and small intestine

Liver and Gallbladder• Reduction in portal venous flow secondary to

the fall in cardiac output• Increased hepatic arterial flow “ hepatic

arterial buffer response”• 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

Large Bowel

• Constipation• Abdominal distension

RENAL FUNCTIONS DURING MECHANICAL VENTILATION

Systemic inflammatory and ischemic effects

Renal Effects of MV

• The usual renal response to reduction of cardiac output and mean arterial pressure

• Reduction in urine output secondary to a fall in the transmural pressure of the right atrium that results in reduction of the secretion of atrial naturitic peptide and the activation of renin-angiotensin-aldosterone system and pituitary vasopressin secretion

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 a normal compliant lung– >20% is transmitted in patients with decreased

lung compliance

ASYNCHRONY WITH MECHANICAL VENTILATION

Patient, Mode, and Operator effects

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

Ventilation complicationsMode specific

PCVPCV

What About New Modes?

Auto ModeAuto Mode

AutoFlowAutoFlow

PPSPPS

VSVS

Mode Specific Complications

Summery: MV complicationsProcedure

Mechanical Ventilation

Mechanical Ventilation and Disease

Mechanical Ventilation, Disease , and Operator