Aortic Aneurysms and Their Anaesthetic Management
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Transcript of 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