PerioperativeVisual Loss

Associated with Spine Surgery

Agina

AginaM. Kempen, CRNA

M. Kempen, CRNA

Chief Nurse Anesthetist

Chief Nurse Anesthetist

St. Clair Hospital

St. Clair Hospital

Pittsburgh, PA

Pittsburgh, PA

Website/Resources:

Website/Resources:

www.asaclosedclaims.org

Miller

Miller ’’s Anesthesia Sixth Edition

s Anesthesia Sixth Edition

Anesthesiology 2006; 104:1319

Anesthesiology 2006; 104:1319-- 2828

Introduction

��Rare, estimated at 0.0008% to 0.003%.

Rare, estimated at 0.0008% to 0.003%.

��May be under

May be under-- reported due to litigation.

reported due to litigation.

��Questionably on the rise.

Questionably on the rise.

��In 1999 ASA established Postoperative

In 1999 ASA established Postoperative

Visual Loss Database with 23 patients.

Visual Loss Database with 23 patients.

��Will focus on varying degrees of visual

Will focus on varying degrees of visual

loss, including blindness, following spine

loss, including blindness, following spine

surgery in the prone position.

surgery in the prone position.

Anatomy of the Visual Pathway

��Cornea/Lens

Cornea/Lens ----focus light on retina

focus light on retina

��IrisIris----controls amount of light

controls amount of light

��Ciliary

Ciliarybody

body----produces aqueous humor

produces aqueous humor

��3 chambers:

3 chambers:

��Anterior

Anterior ----cornea to iris

cornea to iris

��Posterior

Posterior ----iris to

iris to ciliary

ciliarybody to vitreous

body to vitreous

��Vitreous

Vitreous ----contains jelly

contains jelly-- like vitreous humor

like vitreous humor

��Layers:

Layers:

��Sclera,

Sclera, Choroid

Choroid, Retina

, Retina

Retina

��Outer retina contains photoreceptors, rods and cones.

Outer retina contains photoreceptors, rods and cones.

��Rods: night vision and motion detection

Rods: night vision and motion detection

��Cones: central reading and color vision

Cones: central reading and color vision

��Inner retina contains neurons for transmission of

Inner retina contains neurons for transmission of

visual information to the brain

visual information to the brain

Fovea Centralis(Macula)

��Retina thins

Retina thins

��No support structures, few nerve fibers, no rods

No support structures, few nerve fibers, no rods

��Consists entirely of cones

Consists entirely of cones----suited for color and acute

suited for color and acute

vision.

vision.

(Williams EL: AnesthAnalg1995;80:1018-29)

Ocular Blood Supply

��Ophthalmic artery

Ophthalmic artery----

supplies most of eye

supplies most of eye

��Ocular branches

Ocular branches----

��Central Retina Artery

Central Retina Artery

(CRA)

(CRA)

��Posterior

Posterior Ciliary

CiliaryArtery

Artery

Trunks (PCA)

Trunks (PCA)

��CRA sends branches to

CRA sends branches to

supply retina and optic

supply retina and optic

nerve (ON).

nerve (ON).

��Main

Main PCAs

PCAsdivide into

divide into

short

short PCAs

PCAs(( sPCAs

sPCAs ).).

��sPCAs

sPCAssupply posterior

supply posterior

choroid

choroidand portion of the

and portion of the

ON.

ON.

Ocular Blood

Supply

��Circle of

Circle of Zinn

Zinn-- Haller

Haller

��formed by the medial and

formed by the medial and

lateral

lateral sPCAs

sPCAsaround the ON.

around the ON.

��from here are derived the

from here are derived the pial

pial

and

and choroid

choroidbranches.

branches.

��subject to anatomic variation

subject to anatomic variation

��complete in 77% of humans

complete in 77% of humans

Watershed

Zones

��PCA supply is subject to individual variation.

PCA supply is subject to individual variation.

��PCAs

PCAsare end

are end-- arteries without

arteries without anastamosis

anastamosis ..

��Region between each end

Region between each end-- artery supply is a

artery supply is a

watershed zone.

watershed zone.

��Hypotension could lead to poor perfusion.

Hypotension could lead to poor perfusion.

Posterior Optic Nerve

��Blood supply

Blood supply-- pial

pial

arteries and branches

arteries and branches

of CRA.

of CRA.

��Anatomic variation

Anatomic variation

can influence

can influence

watershed geography

watershed geography

��Blood flow less than

Blood flow less than

the anterior ON.

the anterior ON.

(Williams EL: AnesthAnalg1995;80:1018-29)

ChoroidalVessels

��Provide oxygen to outer layers of retina, where

Provide oxygen to outer layers of retina, where

photoreceptors are located.

photoreceptors are located.

��6060-- 80% of retinal oxygen supply is from

80% of retinal oxygen supply is from choroid

choroid..

��Blood flow is high (2000 ml/min/100g) and oxygen

Blood flow is high (2000 ml/min/100g) and oxygen

extraction is low (3%).

extraction is low (3%).

��Relatively large oversupply of perfusion.

Relatively large oversupply of perfusion.

Retinal Vessels

��Nourishes the inner 2/3 of the retina.

Nourishes the inner 2/3 of the retina.

��Blood flow is low (40

Blood flow is low (40-- 100 ml/min/100g) and extraction

100 ml/min/100g) and extraction

is high (38%).

is high (38%).

��Relatively limited blood flow to neuronal ganglia cells

Relatively limited blood flow to neuronal ganglia cells

that have a low tolerance to ischemia.

that have a low tolerance to ischemia.

(Williams EL:

(Williams EL: Anesth

AnesthAnalg

Analg1995;80:1018

1995;80:1018-- 29)

29)

Retina and Choroid

��Autroregulates

Autroregulateswith changes in arterial

with changes in arterial

blood pressure, oxygen and CO2 tension.

blood pressure, oxygen and CO2 tension.

��Inhalation of

Inhalation of hypercapneic

hypercapneicgas increases

gas increases

blood flow.

blood flow.

��Atherosclerosis is associated with defective

Atherosclerosis is associated with defective

autoregulation

autoregulation..

��Blood flow may be altered with anesthesia

Blood flow may be altered with anesthesia

and surgery.

and surgery.

Visual Loss: Symptoms

��Blurry vision to complete blindness

Blurry vision to complete blindness

��Unilateral or bilateral

Unilateral or bilateral

��Complete or partial loss of light

Complete or partial loss of light

��Unfamiliar to most anesthesia providers

Unfamiliar to most anesthesia providers

��May be attributed to anesthetics, eye

May be attributed to anesthetics, eye

ointment.

ointment.

��All patients with symptoms should receive

All patients with symptoms should receive

an

an opthalmologic

opthalmologicexam.

exam.

Central Retinal Artery Occlusion

��Decreases blood flow to entire retina.

Decreases blood flow to entire retina.

��Mechanisms of injury:

Mechanisms of injury:

��1. Emboli

1. Emboli----incidence of

incidence of microemboli

microemboliafter OHS is

after OHS is

almost 100%.

almost 100%.

��2. 2. Atheromatous

Atheromatousdisease

disease

��3. Inflammation, such as

3. Inflammation, such as arteritis

arteritis

��4. Vasospasm

4. Vasospasm

��5. Increased IOP and/or local venous congestion

5. Increased IOP and/or local venous congestion

resulting in low retinal perfusion pressure:

resulting in low retinal perfusion pressure:

��I.e. external pressure on the eyes in the prone position or

I.e. external pressure on the eyes in the prone position or

the surgical

the surgical ligation

ligationof the external jugular veins.

of the external jugular veins.

CRAO Resulting from Low Retinal

Perfusion Pressure

��RPP=MAP

RPP=MAP --IOP

IOP --CVP

CVP

��Increased risk with deliberate hypotension/prone

Increased risk with deliberate hypotension/prone

��Improper positioning of head

Improper positioning of head----compression of

compression of

ocular and

ocular and peri

peri --orbital contents.

orbital contents.

��Increased incidence:

Increased incidence:

��Altered facial anatomy

Altered facial anatomy

��Osteogenesis

OsteogenesisImperfecta

Imperfecta

��Exophthalmos

Exophthalmos

��Asian descent with lower nasal bridge

Asian descent with lower nasal bridge

��In older reports, use of horseshoe headrest.

In older reports, use of horseshoe headrest.

HeadproneRP3

Eye Injury Issue Leads to New Protective

Helmet Device and Research on Face

Pressures from Prone Positioning on OR

Table

Normal Fundoscopy

��Normal Optic

Normal Optic

Disk

Disk

��Normal Vessels

Normal Vessels

without

without

Hemorrhage

Hemorrhage

��Healthy Yellow

Healthy Yellow--

Red Retina

Red Retina

CRAO Fundoscopy

��Retinal pallor

Retinal pallor --

ischemia

ischemia

��Narrowed retinal

Narrowed retinal

arterioles

arterioles

��Cherry

Cherry-- red spot in the

red spot in the

fovea

fovea-- retina is

retina is

ischemic and

ischemic and

underlying

underlying choroid

choroidis is

visible.

visible.

Central Retinal Artery Occlusion

��Neck/nasal surgery

Neck/nasal surgery-- highest proportion of CRAO

highest proportion of CRAO

due to direct vascular damage or spasm

due to direct vascular damage or spasm

��Other Symptoms:

Other Symptoms:

��Possible Ocular Muscle Impairment

Possible Ocular Muscle Impairment

��Facial or

Facial or Periorbital

PeriorbitalEdema

Edema

��Prognosis:

Prognosis:

��In most cases, permanent loss of vision

In most cases, permanent loss of vision

��Treatment:

Treatment:

��No satisfactory treatment

No satisfactory treatment ----ocular massage, IV

ocular massage, IV

Diamox

Diamox, 5% CO2 inhalation, localized hypothermia

, 5% CO2 inhalation, localized hypothermia

Central Retinal Artery Occlusion

��Prevention

Prevention

��Avoid compression of globe

Avoid compression of globe----surgeon

surgeon’’ s arm

s arm

��If prone, use of padded headrest with eye/nose

If prone, use of padded headrest with eye/nose

opening

opening

��If head does not fit in foam headrest, consider

If head does not fit in foam headrest, consider

securing head in pins.

securing head in pins.

��Intermittent exam of eyes in prone position

Intermittent exam of eyes in prone position

��Position head straight down in neutral position.

Position head straight down in neutral position.

��Limited usage of deliberate hypotension with

Limited usage of deliberate hypotension with

prone

prone Trendelenberg

Trendelenberg

��““Air Maneuvers

Air Maneuvers ””and TEE during CP Bypass

and TEE during CP Bypass

Ischemic Optic Neuropathy (ION)

��Occurs after surgery or non

Occurs after surgery or non-- surgical bleeding

surgical bleeding

��Develops spontaneously

Develops spontaneously

��Leading cause of sudden visual loss in patients

Leading cause of sudden visual loss in patients

>50 years old

>50 years old

��Can be either

Can be either arteritic

arteriticor non

or non-- arteritic

arteritic

��Two types:

Two types:

��1.Anterior Ischemic Optic Neuropathy (AION)

1.Anterior Ischemic Optic Neuropathy (AION)

��more common and more extensively studied

more common and more extensively studied

��2.Posterior Ischemic Optic Neuropathy (PION)

2.Posterior Ischemic Optic Neuropathy (PION)

Ischemic Optic Neuropathy

(Williams EL: AnesthAnalg1995;80:1018-29) ��AION

AION----

��caused by interruption

caused by interruption

of blood supply to

of blood supply to

anterior portion of

anterior portion of

optic nerve.

optic nerve.

��PION

PION----

��produced by decreased

produced by decreased

oxygen delivery to the

oxygen delivery to the

posterior,

posterior, retrolaminar

retrolaminar

portion of the optic

portion of the optic

nerve.

nerve.

ArteriticIschemic Optic Neuropathy

��Anterior

Anterior

��Inflammatory process due to temporal

Inflammatory process due to temporal

arteritis

arteritis ----biopsy to confirm.

biopsy to confirm.

��Majority of patients have had flu

Majority of patients have had flu-- like

like

symptoms.

symptoms.

��Must emergently be treated with steroids.

Must emergently be treated with steroids.

��Posterior

Posterior

��Very rare inflammatory process

Very rare inflammatory process

��Found with systemic lupus, sickle cell

Found with systemic lupus, sickle cell

disease.

disease.

Causes of PerioperativeAnterior

Ischemic Optic Neuropathy

��Anatomic and physiologic variations in the

Anatomic and physiologic variations in the

circulation of the optic nerve

circulation of the optic nerve

��Underperfused

Underperfusedareas of the anterior optic nerve

areas of the anterior optic nerve

are found especially in patients with increased

are found especially in patients with increased

IOP and systemic hypotension.

IOP and systemic hypotension.

��Small optic disk may play role in AION

Small optic disk may play role in AION

susceptibility

susceptibility

��Axons that pass through narrowed opening into

Axons that pass through narrowed opening into

eye are prone to injury.

eye are prone to injury.

Surgeries in Which AION and PION

Have Occurred:

��Supine Position:

Supine Position:

��Cardiac and Cardiovascular Surgery *

Cardiac and Cardiovascular Surgery *

��Abdominal, OB and

Abdominal, OB and Gyn

GynSurgery

Surgery

��Head and Neck Surgery *

Head and Neck Surgery *

��Lateral Position:

Lateral Position:

��Thoracotomy

Thoracotomy

��Hip Surgery

Hip Surgery

��Prone Position:

Prone Position:

��Spine Surgery *

Spine Surgery *

Fundoscopyof Acute Anterior Ischemic

Optic Neuropathy

��Early stages

Early stages----Optic

Optic

disk swelling (edema)

disk swelling (edema)

and a splinter

and a splinter

hemorrhage at the

hemorrhage at the

optic disk margin

optic disk margin

Acute Anterior ischemic optic neuropathy

www.asaclosedclaims.org

Fluoresceinfundus

angiograms during

the early stages of

AION, showing no

circulation in parts

of the choroidand

optic disc (dark

areas correspond

to absence of

filling by

fluoresceindye).

Posterior Ischemic Optic Neuropathy

��Area not as well

Area not as well --vascularized

vascularizedas the anterior

as the anterior

portion of optic nerve (ON).

portion of optic nerve (ON).

��Caused by low

Caused by low-- flow state from systemic

flow state from systemic

hypotension; emboli or venous stasis could

hypotension; emboli or venous stasis could

contribute to PION.

contribute to PION.

��Initial period can be symptom

Initial period can be symptom-- free.

free.

��Initial normal

Initial normal fundoscopy

fundoscopy..

��Within 6 weeks, optic disk atrophies and

Within 6 weeks, optic disk atrophies and

becomes pale.

becomes pale.

Factors Associated with Perioperative

Ischemic Optic Neuropathy

��Systemic hypotension

Systemic hypotension

��Blood loss/anemia

Blood loss/anemia

��Increased intraocular pressure

Increased intraocular pressure

��Abnormal

Abnormal autoregulation

autoregulationof ON circulation

of ON circulation

��Anatomic variation of ON vasculature

Anatomic variation of ON vasculature

��Emboli

Emboli

��Use of

Use of vasopressors

vasopressors

��Presence of systemic disease

Presence of systemic disease

��Retrobulbar

Retrobulbarhemorrhage

hemorrhage

Factors Related to Ischemic Optic

Neuropathy

��Hypotension

Hypotension----

��Not present in all cases but cited as important.

Not present in all cases but cited as important.

��Can lead to decrease in perfusion pressure of

Can lead to decrease in perfusion pressure of

optic nerve (ON).

optic nerve (ON).

��Anterior ON at risk because of anatomic

Anterior ON at risk because of anatomic

variation or abnormal

variation or abnormal autoregulation

autoregulation..

��Posterior ON at risk because of limited blood

Posterior ON at risk because of limited blood

supply to area.

supply to area.

��““Safe

Safe””lower limits of blood pressure not known.

lower limits of blood pressure not known.

Factors Related to Ischemic Optic

Neuropathy

��Blood Loss / Anemia

Blood Loss / Anemia

��From case reports, considerable blood loss.

From case reports, considerable blood loss.

��Decreased hemoglobin levels

Decreased hemoglobin levels intraoperatively

intraoperatively..

��Presently, routine clinical practice based on

Presently, routine clinical practice based on

NIH Panel on Blood Transfusion is not to

NIH Panel on Blood Transfusion is not to

transfuse for

transfuse for Hgb

Hgb> 8

> 8 g/dL

g/dL..

��Are decreased

Are decreased Hgb

Hgblevels placing patients at

levels placing patients at

risk for ION?

risk for ION?

Factors Related to Ischemic Optic

Neuropathy

��Increased Intraocular Pressure

Increased Intraocular Pressure

��ION reported with massive fluid replacement in

ION reported with massive fluid replacement in

prone position.

prone position.

��Many cases report no pressure to orbits (head in pin

Many cases report no pressure to orbits (head in pin

holders).

holders).

��Massive fluid therapy with or without prone

Massive fluid therapy with or without prone

��Increased IOP

Increased IOP

��Accumulation of fluid in the optic nerve (ON).

Accumulation of fluid in the optic nerve (ON).

��Small vessels on

Small vessels on ON

ONcompressed, resulting in

compressed, resulting in

decreased arterial supply

decreased arterial supply

��Increased orbital venous pressure, venous stasis

Increased orbital venous pressure, venous stasis

Factors Related to Ischemic Optic

Neuropathy

��Autoregulation

Autoregulationand Anatomic Variation of

and Anatomic Variation of

the Optic Nerve

the Optic Nerve

��Anatomic variation may predispose to ION.

Anatomic variation may predispose to ION.

��Location of potential watershed zones in ON

Location of potential watershed zones in ON

circulation plus the presence of disturbed

circulation plus the presence of disturbed

autoregulation

autoregulationin healthy patients cannot be

in healthy patients cannot be

predicted at this time.

predicted at this time.

��20% of healthy patients with increased IOP

20% of healthy patients with increased IOP

have been found to have abnormal

have been found to have abnormal

autoregulation

autoregulation..

Factors Related to Ischemic Optic

Neuropathy

��Emboli

Emboli

��Most likely to occur during cardiac surgery.

Most likely to occur during cardiac surgery.

��Air embolism through patent foramen

Air embolism through patent foramen ovale

ovale

��Vasopressors

Vasopressors

��Anterior ION related to excessive secretion of

Anterior ION related to excessive secretion of

vasoconstrictors, lowering optic nerve perfusion.

vasoconstrictors, lowering optic nerve perfusion.

��Case reports of patients with ION after prolonged

Case reports of patients with ION after prolonged

use of epinephrine and

use of epinephrine and phenylephrine

phenylephrineduring

during

operative procedure.

operative procedure.

Factors Related to Ischemic Optic

Neuropathy

��Patients with Hypertension, DM, CAD, or

Patients with Hypertension, DM, CAD, or

Previous Stroke

Previous Stroke

��Not present in all patients

Not present in all patients

��Typically found in patients for cardiac surgery.

Typically found in patients for cardiac surgery.

��Theory that

Theory that perioperative

perioperativeION is related to

ION is related to

atherosclerosis

atherosclerosis ----ON vasculature responds

ON vasculature responds

abnormally to changes in perfusion pressure

abnormally to changes in perfusion pressure

(disturbed

(disturbed autoregulation

autoregulation).).

Factors Related to Ischemic Optic

Neuropathy

��Retrobulbar

RetrobulbarHemorrhage

Hemorrhage

��Direct surgical injury to ON

Direct surgical injury to ON

��Indirect damage by compression more common

Indirect damage by compression more common

��Paresis of eye muscles often seen

Paresis of eye muscles often seen

��Outcome poor, usually permanent blindness

Outcome poor, usually permanent blindness

Benumof2004

CSA Refresher Course San Diego

Ischemic Optic Neuropathy

��Prognosis and Treatment

Prognosis and Treatment

��No proven treatment

No proven treatment

��Diamox

Diamoxlowers IOP, may improve flow to

lowers IOP, may improve flow to

anterior ON and retina.

anterior ON and retina.

��Diuretics may decrease edema

Diuretics may decrease edema

��Corticosteroids may decrease ON swelling in

Corticosteroids may decrease ON swelling in

acute phase.

acute phase.

��Increasing systemic BP /

Increasing systemic BP / Hgb

Hgblevel

level

��Maintain head

Maintain head-- up position to decrease ocular

up position to decrease ocular

venous pressure.

venous pressure.

��Surgical ON decompression ineffective

Surgical ON decompression ineffective

Ischemic Optic Neuropathy:

Prevention

Prevention

��Status of patient

Status of patient ’’s ON circulation is unknown.

s ON circulation is unknown.

��Presently, no effective ON monitoring available.

Presently, no effective ON monitoring available.

��Maintain systemic blood pressure as close to

Maintain systemic blood pressure as close to

baseline as possible (BP > 75% of control).

baseline as possible (BP > 75% of control).

��If If vasopressors

vasopressorsare used to maintain BP, impact

are used to maintain BP, impact

on

on ON

ONvasculature not known.

vasculature not known.

��Consider

Consider Hgb

Hgboptimization vs. lowest acceptable

optimization vs. lowest acceptable

(( Hgb

Hgb> 9

> 9 g/dL

g/dL, , Hct

Hct> 27%).

> 27%).

��Maintain SaO2 > 95% (? low PEEP).

Maintain SaO2 > 95% (? low PEEP).

Ischemic Optic Neuropathy:

Prevention

Prevention

��CVP placement to monitor venous pressure.

CVP placement to monitor venous pressure.

��Minimize protracted periods of prone and

Minimize protracted periods of prone and

prone/

prone/Trendelenberg

Trendelenbergpositions.

positions.

��Proper positioning

Proper positioning

��Avoid abdominal compression.

Avoid abdominal compression.

��Assure adequate chest excursion.

Assure adequate chest excursion.

��Avoid external pressure to orbits.

Avoid external pressure to orbits.

��Discuss the risk of ION with surgeon.

Discuss the risk of ION with surgeon.

Informed Consent?

��Controversial

Controversial

��Despite potential devastating injury, only

Despite potential devastating injury, only

theories exist to the cause of ischemic optic

theories exist to the cause of ischemic optic

neuropathy.

neuropathy.

��Few clinicians include in informed consent.

Few clinicians include in informed consent.

��Consider including with:

Consider including with:

��Jehovah

Jehovah’’ s Witness patient

s Witness patient

��Case in which surgeon requests deliberate

Case in which surgeon requests deliberate

hypotension/

hypotension/ hemodilution

hemodilutionin prone position.

in prone position.

Practice Advisory:

Anesthesiology 2006; 104: 1319-28

Summary

��ION

ION --multifactorial

multifactorialcauses

causes

��Predisposing factors remain unknown.

Predisposing factors remain unknown.

��““Safe

Safe””limits for hypotension and hemoglobin

limits for hypotension and hemoglobin

levels have not been validated.

levels have not been validated.

��Have documentation of surgeon

Have documentation of surgeon’’ s demand for

s demand for

deliberate

deliberate hypotensive

hypotensiveprone procedures.

prone procedures.

��CRAO

CRAO --avoid compression of globe.

avoid compression of globe.

��All patients experiencing visual changes

All patients experiencing visual changes

need an

need an opthalmology

opthalmologyconsult.

consult.

��Statistics regarding your patient experiencing

Statistics regarding your patient experiencing

postoperative visual loss.

postoperative visual loss.