Aortic Aneurysms and Their Anaesthetic Management

8/4/2019 Aortic Aneurysms and Their Anaesthetic Management

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Aortic aneurysms

and theiranaesthetic

management

Moderator : Dr. Ashwani

Presenter: Dr. Monika


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Largest vessel in the body

the aorta starts at theaortic valve and ends at

the iliac bifucation. Asc. Arch, desc.

Intima , media and adventitia


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Aneurysma meaning awidening.

An aortic aneurysm refers to an abnormal,localized blood vessel wall weakness and

bulging or ballooning(dilation) in a segmentof the aorta, usually 50% over the normal

diameter. Normal diameter of aorta: 3cm at the origin

2.5cm in desc. portionof thorax

1.8-2cm in the abdomen


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TYPES:

Based on location:

Abdominal aorticaneurysms(AAA): 75%,infrarenal most common

Thoracic aortic aneurysm:25%, ( asc., arch, desc.)

Thoracoabdominal aorticaneurysm (TAAA):

True aneurysms: if contain all the three

layers.

False/pseudoaneurysm: if only the outerlayer remains.

Acc. to shape:

Fusiform (symmetrical)

Saccular (asymmetrical)


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TAA

Diameter of the thoracic aorta1.5 times greater than normal(or larger)

Incidence 5.9 per 100,000 person-

years

Median age 65 years

(2-4)M>F

Desc. TAA> Asc.TAA> Aortic archTAA


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CRAWFORD CLASSIFICATIONOF TAAA


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DEGENERATION & DISSECTION

Atherosclerosis(80%)

Chronic aortic dissection(17%)

Marfans syndrome, Loeys Dietz syndrome

Ehlers-danlos syndrome

Familial thoracic aortic aneurysm syndrome

Congential aortic aneurysms (Bicuspid aortic valve,coarctation)

Traumatic aneurysms

Syphilitic (rare)

Tuberculosis aneurysms

Mycotic aneurysm

Vasculitides : takayasus arteritis, giant cell arteritis

Spondyloarthopathies: Bechets ds causes TAAA

Annuloaorticectasia: isolateddilation of asc aorta, aortic root,

aortic valve annulus Central AR


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Aortic dissection

Ascending (65%), arch (20%),descending thoracic (10%),abdominal (5%)

Acute (2/3), chronic (1/3)

STANFORDCLASSIFICATION

TypeA: involveascending aorta

TypeB: dont involveascending aorta


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DEBAKEY CLASSIFICATION


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CLINICAL FEATURES

Remain asymptomatic for long(silent killer)

Chest or back pain

Hoarseness Atelectasis

Dysphagia

Dyspnea

Superior vena cava syndrome

Wheezing, cough, hematemesis, hemoptysis

Symptoms of AR

Embolism with stroke,mesentric or limb ischemia

Rupture of asc. Aorticaneurysm in to pericardial

sac causes cardiac

temponadeDesc. AA rupture causes

hemothorax, aortobronchialfistula, aortoesophageal

fistula


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DIAGNOSIS

Abnormal chest x-ray

Transthoracic ultrasound examination

Aortic angiography & digital subtraction

angiography (gold standard)

CT, MRI: 87-100%

CTA

MRA

TEE : 99-100%

Abdominal USG


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TREATMENT OPTIONS

Medical management/monitoring(watchfulwaiting)

Open surgery

Endovascular repair

No proven lifestyle changes can decrease the size of TAAs.

TEVAR animation video
http://tevar%20animation.wmv/http://tevar%20animation.wmv/


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Medical management / monitoring

TAAs under 5cm

BP lowering drugs

Goal to maintain SBP between 105-

120mmhg Long term beta-blocker therapy .

Statins

Restriction of some physical activities.

Serial surveillance by imaging studies 2nd imaging study obtained 6months after

initial diagnosis


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Atherosclerotic aneurysm diameter

Ascending aorta > 5.5cm

Descending aorta > 6.5cm

Marfans or familial thoracic aneurysm diameter

Ascending aorta > 5.0cm

Descending aorta > 6.0cm

Severe aortic regurgitation

Aortoannular ectasia with dilated aortic root

Congential bicuspid aortic valve

Contained or impending rupture

Symptoms refractory to medical management

Increase in aneurysm diameter > 1cm/year


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REPAIR OPTIONS

Requires single small incision in the groinarea.

An endovascular graft is inserted through the femoralarteryvia a catheter and deployed inside the lumen, reliningthe aorta.

Average ICU stay: 2-3 days

Average recovery time: 1-2 weeks

Endovascular surgery:


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REPAIR OPTIONS

Requires thoracotomy

Aorta is cross-clamped above diseased aorticsegment

Affected segment is replaced with fabric surgicalgraft

Average hospital stay: 2-3 weeks

Average recovery time: 3 months

Elective repair: up to 10% mortality

Emergent repair: up to 50% mortality

Open surgery:


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1. Urgency of the surgery : emergent, urgent orelective

2. Pathology, anatomic extent of the lesion provideinformation about physiologic impact and

consequences of the lesion, permittinganaesthesiologist to anticipate potential difficultiesassociated with anaesthetic procedures, problemsrelated to surgical repair and postoperativecomplications.

3. Baseline functional reserve of each organ system :(often elderly and have CO-EXISTING DISEASES)


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Preexisting or associated medical conditions

Heart:

>50% have severe CAD. 90% hypertensive

Left ventricular systolic dysfunction 5 times more common

Valvular dysfunction, arrhythmias, cardiomyopathy,Prior aortic surgery

(increased risk of CHF, perioperative MI, death)

Pulmonary disease:

COPD, chronic bronchitis, smoking

Increased risk of post-op pulmonary complications

PFTs useful in evaluating &optimizing respiratory function

Baseline hypercapnia(paCo2>45mmhg) increases the risk

Bronchodilators may be indicated but risk of beta agonist inducedarrhythmia or MI should be considered.

Antibiotics ; short course of glucocorticoids


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Renal insufficency:

Alters fluid management

Serum creatinine level>2mg/dl

creatinine clearance


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4. Hemodynamic status, intravascular volume access andmanagement

5. Airway patency:Aortic pathology distorting trachea/bronchusmay increase difficulty to tracheal and endobronchial intubation.

6.Pre-operative medications:

Antihypertensives, beta-blockers, other cardiacmedications, pulmonary, antiseizure medicationcontinued till morning of surgery

Discontinue oral hypoglycemics(metformin)

Warfarin, Coumadin discontinued 3-7 days before Aspirin, clopidrogel 1week

Ticlopidine 14 days

Add heparin if need anticoagulation


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7. Prepare blood/PRC (6-15 units), FFP 10-20 ml/kg,plateletpheresis or platelet concentrate (10-20 units),cryoprecipitate 10-20 units

8. Discuss anesthetic and operative plan with thesurgical team to properly prepared for all possiblecontingencies.

9. Assess risk of pulmonary aspiration

10. Plan for CPB, left heart bypass or circulatory arrest


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Room Preparation1. Equipments

Single lumen ETT, double lumen ETT, endobronchial blocker

Equipments assisted difficult intubation

Infusion pump x 3 , Syringe pump x 3

Warmer : water-bath x 1, forced-air warmer x 1, mini-warmerapparatus x 2

IV set infusion x 5, Blood/blood component infusion set x 10

Rapid infuser system(1500ml/min)

Extension tubings, Three-ways x 10

IV cannulas of different sizes

Double-lumen , triple lumen IV catheter

Swan ganz catheter 7Fr x 1 + Terrumo sheath introducer 8 Fr x1


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2. DRUGS :Cardiovascular drugs

Adrenalin (0.1 mg/ml) = 10 ml forIV bolus

Atropine (0.6 mg/ml)

norepinephrine : Bolus(0.1ug/kg) ,2-20ug/min infusion

dopamine (1-20ug/kg/min)

Nitroprusside (100ug/ml) ; IVinfusion(0.5-10ug/kg/min

Nitroglycerin (100 ug/ ml) = 100 mlfor IV infusion

Esmolol (0.2-0.5mg/kg);50-200ug/kg/min

Phenylephrine 50-100ug;0.25-1ug/kg/min

Anticoagulant:

Heparin 1 mg (100 units)/kgwithout using CPB

Heparin 3 mg (300 units) kg

when using CPB

For decreasing postop bleeding:

- Transamin 10-20 mg/kg IV bolus

-Desmopressin 0.3 g/kg IV-EACA 5-10g f/by 1g/hr

Aprotinin 280mg; 3mg/kg/hr

- Recombinant activated factor VIIa(Novoseven) 90 g/kg IV,

Diuretics: 25% mannitol 0.25-1gm/kg

Furosemide 40 mg/ml

Antiarrhymic agents: xylocard,

cordarone (150 ml/3 ml/amp), MgSO4 (2gm)

Sodiumbicarb 50 ml/amp

10% Calciumgluconate/chloride 10 ml/amp

Antibiotics :

HumulinR and 50% glucose 50 ml x 2

Others :


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Premedication

Patient should be brought in preoperative ward 1 hr

before surgery

Secure large bore intravascular access

Alleviate fear, anxiety and pain

Midazolam 0.01-0.15mg/kg i/v

Morphine 0.05-0.1mg/kg i/m or fentanyl 0.5-1ug/kg i/v

Continue cardiac medications till morning of surgery

Small oral dose of clonidine 2ug/kg reduce incidence ofperioperative MI without affecting hemodynamics

Catheterize patient and note urinary output


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MONITORING:

Continuous ECG, NIBP,pusleoximetery,EtC02,

Intra-arterial catheter: (IBP)

Right Radial artery,

Left radial artery,

Femoral artery or dorsalis pedis artery

Central venous catheterization

Pulmonary artery catheterization

Transesophageal echocardiography: TEEprovide diagnostic information, assessment ofventricular function and intravascular volume status

HEMODYNAMICMONITORING:


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Neurophysiologicmonitoring Electroencephalography (EEG)

Evoked potentials:

Somatosensory(SSEP); Motor (MEP)(to detect spinal cord ischemia)

Lumbar CSF pressure

Jugular venous bulb O2 saturation

Temperature monitoring:Upper body core temp. : nasopharyngeal or esophageal

Lower body core temp. : bladder, rectal

Others:

Arterial blood gases, electrolytes (Na+, K+, Ca++), Hct Activated clotting time (ACT), (Coagulogram)

Blood sugar

Urine output

Estimated blood loss


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Intra-operative

management

Position : Discuss with thesurgeon

Supine for median sternotomyand endovascular stent repair

Rightlateraldecubitus for left

thoracotomy


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COMPANY LOGO

Operative techniques for repair ofTAAA

Simple aortic cross clamping/ clamp-and-sew technique

Passive GOTT shunt

Left Heart bypass Deep hypothermic circulatory arrest


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COMPANY LOGO

Performed without ECC support.

Surgical simplicity. Obligatory ischemia to organs distal to clamp

Increased incidence of paraplegia and renalfailure

Cross-clamp time should not exceed 30minutes

Proximal aortic hypertension, bleeding fromarterial collaterals, hemodynamic instability

upon reperfusion


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Increased arterial blood pressure above the clamp

Decreased arterial blood pressure below the clamp

Clamping of the

increases :mean arterial pressure by 35%

Central venous pressure by 56%

Mean pulmonary arterial pr by 43%

Pulmonary capillary wedge pr by 90%

HR & LV stroke work do not changed significantly

LV wall tension

Ejection fraction

coronary blood flow


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AT SUPRACELIAC AORTIC CROSS-CLAMPING:

MAP increase by 54% PCWP by 38%

EF decreases by 38%

Significant wall motion abnormalities ATSUPRARENALLEVEL: similar but smaller

CVS changes

ATINFRARENALLEVEL: minimal cnanges withno wall motion abnormalities


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Blood volume redistribution hypothesis


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b l h


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Metabolic changes

Total body 02 consumption

Total body CO2 production

mixed venous O2 saturation

total body O2 extraction

epinephrine & norepinephrine Tissue perfusion distal to cross clamp depends on

proximal aortic pressure & independent of CO.

Renal blood flow markedly decrease ( 83-90%) duringthoracic aortic cross clamping

Increased plasma renin activity, other mediators like

plasma endothelin, myoglobin, PGs contribute to

decreased renal perfusion

Respiratory alkalosis

Metabolic acidosis


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Therapeutic interventions

Afterload reduction

Sodium nitroprusside Inhaled anaesthetics

Amrinone

Shunts and aortofemoral bypass

Preload reduction Nitroglycerin

Controlled phlebotomy

Atrial to femoral bypass

Renal protection Fluid administration Distal aortic perfusion techniques

Selective renal artery perfusion

Mannitol and drugs to augment renal perfusion


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Hypotension

Decrease myocardial contractility Decrease CO

METABOLIC:

Inc total body O2 consumption

Decrease mixed venous O2 saturation

Metabolic acidosis

Therapeutic intervention:

inhaled anaesthetic

vasodilators fluid administration

vasoconstrictors

Sodium bicarbonate

Reapply clamp for severe hypotension


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Aortic unclamping


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COMPANY LOGO

Tapered heparin coated tube so that bothends can serve as arterial cannulas

Proximal cannulation sites: ascending aorta

or aortic arch Distal cannulation sites: distal descending

thoracic aorta, iliac artery or femoral artery

Passive shunting of blood from proximal to

distal aorta Simple, inexpensive, requires only partial or

no anticoagulation


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COMPANY LOGO

Partial left heart bypass

Left atrial- to- femoral bypass

Partial heparinazation i.e 100U/kg reqd. 5minutes before cannulation

Initial flow rate of 500ml/min

Mean arterial pressue of 80-100mmhg abovethe cross clamp and atleast 60mmhg belowthe cross clamp

Moderate hypothermia 32C


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COMPANY LOGO

Proximal aortic anastomosis

visceral aortic anastomosis

distal aortic anastomosis


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COMPANY LOGO

Deep hypothermic circulatory aresst

Surgery of arch of aorta

Profound hypothermia of 15*C

30 minutes safe limit of DHCA

With selective antero or retrograde cerebralperfusion with cold oxygenated safe limit of90mins

Femoral-femoral bypass


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COMPANY LOGO

Surgery involving ascending aorta

Median sternotomy

Cardiopulmonary bypass

Intra-operative course may be complicated by aortic regurgitation, long cross-clamping time, large intr

a-operative blood loss

Left radial artery for IBP

Drugs causing bradycardia should be usedcautiously.

Left ventricular vent is necessary during CBP

wheat procedure

Bentall procedure


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To Maintain hemodynamic stability during induction,intubation and maintenance of anesthesia withcardiac, vasoactive and fluid management

To prevent rupture of aneurysm(during induction)

Gentle laryngoscopy and endotracheal /endobronchial intubation

Avoid hypo or hyperthermia

Organ protection: myocardium, CNS, spinalcord,kidney,mesentries

Prevention and management of hemorrhage andcoagulopathy

Anaesthetic techniq e


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Anaesthetictechnique:Induction

Slow & controlled

PREOXYGENATION

No single best anaesthetic technique

Intravenous induction agents: etomidate,

propofol, thiopental or ketamine(severe

hypotension) Combination with fentanyl(3-5ug/kg) and

midazolam 1-2mg IV or low dose volatile

anaesthetic


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SBP b/w 105-115mmhg

HR b/w 60-80 b/min CI b/w 2-2.5L/min/m2 ESMOLOL (10-25MG), NITROPRUSSIDE (5-25uG), NTG(50-

100uG) PHENYLEPHRINE(50-100uG) Should be available for

bolus if needed

Intubation: Consider emergent and urgent patient as full stomach.

Rapid sequence induction and intubation should beperformed

Succinylcholine or short-acting NDP (cis-atracurium canbe used


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One lung ventilation

For left thoracotomy or TAAA

incision

Double-lumen endobronchial (DLT)

tube(left-sided DLT) or single lumen ETT with

endobronchial blocker

Exchanging the DLT at the end of

procedure can be difficult as the

airway may be edematous

use ofTube exchange catheter

Equipments for emergency airway


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Combination of O2, N2O, potent opoids(fentanyl,

sufentanil), Low dose potent volatile agents(isoflurane,sevoflurane,desflurane.

Muscle relaxant: preferred

Vecuronium,0.08-0.12 mg/kg

Rocuronium,0.45-0.9mg/kg Cisatracurium0.1-0.15 mg/kg

TIVA may be optimal if transcranial MEP monitoring is

used

Nitroprusside (0.5-2ug/kg/min )and esmolol (25-300ug/kg/min) infusion

EXTUBATION should always take place in the ICU & only

after a significant period of hemodynamic & metabolic

stability


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Throacoabdominal aortic aneurysm extentHypotension or cadiogenic shock Emergency operation

Aortic rupture Presence of aortic dissectionDuration of aortic cross clamp Surgical technique used for repair Prior aortic aneurysm repairOcculsive peripheral vascular disease


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Detection of spinal cord ischemia

Somatosensory evoked potentialsMotor evoked potentials

Immediate onset paraplegiaDelayed onset paraplegia

Strategies used for spinal cord


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Strategies used for spinal cordprotection

MINIMIZE AORTIC CROSS-CLAMP TIME Distal aortic perfusion Passive shunt Partial left heart bypass Partial cardiopulmonary bypass INCREASE SPINAL CORD PERFUSION

PRESSURE Re-implantation of critical intercostal & segmental

arterial branches Lumbar CSF drainage Arterial pressure augmentation (MAP> 85mmhg)

Lumbar CSF drainage


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Lumbar CSF drainage SCPP= distal MAP CSF pressure or CVP Silicon catheter at L3 & L4 interspace

CSF allowed to drain when CSF pressureexceeds 10 mmHg

Complications:extradural/intradural hematoma,

Catheter fracture,intracranial hypotension, headache,

mennigitis, subdural hematomaARTERIAL PRESSURE AUGMENTATION

Maintain MAP in range of 80-100mmhg Spnal cord perfusion pressure above 70mmhg Decreasing lumbar CSF pressure alone may

have negligible effect if MAP is insufficient

D lib t h th i


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Deliberate hypothermia


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Pre-operative spinal cord angiogaphy

for Identifation of great radicular artery(GRA):decreases risk of paraplegia

Intra-operative monitoring of lowerextremity neurophysiologic function

SSEPs: dec in amplitude &latency of SSEP > 14-30minutes increases risk of neurologic deficit

MEPs

Post-operative neurologic assessment for earlydetection of delayed onset paraplegia byserial neurologic examinations


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Renal ischemia &protection

Distal aortic perfusion maintains renal blood flowduring proximal anastomosis

Cathertization of renal arteries and perfusion withiced saline to maintain regional hypothermia

below15C

Mannitol (0.25g/kg) before cross-clamping improvesrenal blood flow.

Loop diuretics less effective

Low dose dopamine(1-3ug/kg/min)

Fenoldopam mesylate(0.1ug/kg/min)a selectivedopamine type 1 agonist dilates renal &splanchicvascular beds


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Blood loss & coagulopathy

Blood loss and transfusion therapy are commonplace

Dilutional coagulopathy common

( low level of platelets, clotting factors, residual heparin, ischemia ofliver,persistent hypothemia)

Transfusion of platelets, FFPs, cryoprecipitates Monitor PT, aPTT, fibrinogen level, platelet count

Antifibrinolytic therapy: E aminocaproic acid 5-10gm f/by 1gm/hr; tranexamic acid 10mg/kg

f/by 1mg/kg/hr Desmopressin : to increase level of von-willibrand factor& factorVIII

Recombinant activated factor VIIa 90ug/kg i/v; repeated after 2 hours

Complete rewarming


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Arterial blood gases and electrolytes should be

measured frequently.

Sodium bicarbonate to correct severe metabolicacidosis(pH


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Post-operative analgesia Thoracotomy & TAAA incision very painful, cause respiratory splinting,

retention of airway secretions post-operative respirtory failure

Epidural analgesia is effective means of providing intra-op &post-opanalgesia

Epidural analgesia regimen should be formulated to minimiseinterference with ability to monitor lower extremity neurologic functionand not cause sympathetic blockade

Bupivicaine 0.05% combined with fentanyl 2ug/ml via PCEA infusion @4-8ml/hr

Bolus administration should be avoided.

Epidural catheter can be inserted prior to, at the time of surgery, or in

the post-operative period Coagulation parameteres should be satisfactory prior to insertion and

during removal of catheter


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Thankyou


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THE SITUATION

AAAs are the tenth leading cause of death in men over 50.

An estimated 1 million men and women worldwide are livingwithundiagnosed AAAs.

Could yourpatient have an undiagnosed AAA?


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AAA

Diameter > 3cm

Atherosclerosis & aging

Infrarenal arota: no vasa vasorum

Prevalence: 10% in men, 3% in women

Perioperative mortality with electiverepair: 2-5%

Emergency repair : 50% When AAAs rupture, only 18% of

patients survive.


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Size of AAA directly related to morbidity and risk ofrupture

>5cm diameter - incidence of rupture substantially

1 year incidence of probable rupture- 35% foraneurysm > 7cm

Mural thrombosis are common


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SYMPTOMS

Asymptomatc

Palpable, pulsatile ,non-tender mass on routine exam/ incidental findingduring imaging of abdomen

Pain or tenderness in the lower back, abdomen

Indications of rupture may include:

Lightheadedness

Sweating

Clammy skin

Nausea/vomitting

Shock

classictriad: abdominal or back pain;

palpable/ pulsatile abdominal mass;

hypotension (


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DIAGNOSIS

Physical examination of abdomen Pulsatile, palpable abdominal mass

Stiff /rigid abdomen

Bruit over the aorta

Abdominal ultrasound , may detect mural thrombosis

As required: MRI, CT or other imaging systems

Angiography rarely done

CTA Abdominal radiography :


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TREATMENT OPTIONS

Medical management/monitoring(watchfulwaiting) :AAAs

Documents

Aortic Aneurysms and Their Anaesthetic Management