Chapter 74 - Ruptured AAA Flashcards by Gary Yang

Causes of symptoms in non-ruptured AAA

1) Acute expansion
2) Intramural hemorrhage
3) Wall degeneration
4) bleeding into thrombus

Preludes rupture

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Bahnson 1953

First successful RAAA repair with homograft

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Cooley + DeBakey 1954

Treated 6 patients with 50% survival

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Hopkinson 1994

First EVAR in rupture

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Trend of death due to RAAA over time

decrease mortality

Male mortality decreased more than female

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Causes of decline in RAAA mortality

1) decrease smoking
2) better cardiovascular risk factor control
3) increase EVAR and repair of elders at risk
4) screening programs

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Mortality post-rupture surgery

31.6%

US 41.6%
UK 41.8%

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Percent of ruptures offered repair in US vs UK

80% US

58% UK

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Post-op mortality causes

1) hemorrhagic shock

2) reperfusion injury

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Wall strength in pressure measurements

Normal = 121 N/cm2
AAA = 65 N/cm2

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Laplace’s Law

Tension proportional to radius and pressure

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Hot spots in wall weakness

localized MMP activity with local weakening

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Typical weakest spot in aortic aneurysm

Posterior wall

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Martin 1965 on theory of wall thrombus

Wall thrombus prevent nutrition transfer therefore weaker wall

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Schurink on wall thrombus and pressure

Thrombus does not decrease pressure

Tested using transducers during OAAA

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Vorp on wall thrombus

Causes local hypoxia resulting in

1) neovascularization
2) inflammation
3) wall thinning
4) increase collagenase –> less elastin and collagen

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% of ruptures that occur at site of mural thrombus

80%

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Classic triad of RAAA

1) pulsatile mass
2) hypotension
3) abdominal/back pain

9% in mis diagnosed group
34% in correctly diagnosed group

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Rate of accurate diagnosis of RAAA upon first physician

23%

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Rate of incorrect diagnosis of RAAA

16-60%

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Common mis diagnosis of RAAA

1) renal colic
2) perforated viscus
3) diverticulitis
4) GI hemorrhage
5) ischemic bowel

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US accuracy to identify RAAA

51%

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Aortocaval fistula sign

1) new onset CHF
2) increase IJ pressure
3) loud new bruit/thrill
4) pulsatile mass

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RAAA sign on plain X-RAY

1) large calcified wall 65%

2) loss of psoas shadow 75%

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CT scan for RAAA in terms of sen/spe, ppv/npv

77% SEN 100% SPE 100% PPV 89% NPV

Time to death from onset of symptomsin ruptures natural course

16 hours median 13% died within first 2 hours of hospital admission

Does getting a CT affect mortality of RAAA

no | shown by IMPROVE

Does transfer to centre with vascular improve outcome

yes | shown by US NIS

Problem with aggressive resuscitation in RAAA

1) increase BP 2) increase hemorrhage 3) hemodilution 4) coagulopathy 5) hypothermia 6) acidosis

Permissive hypotension goals

1) maintain consciousness 2) minimize organ ischemia 3) prevent ST depression 4) SBP 70-80 (IMPROVE showed better survival when it's at least 70)

Proportion of RAAA suitable for EVAR

47-67%

Neck length relationship to RAAA mortality

inversely proportional 15mm increase neck will drop mortality by 20% (IMPROVE)

Balloon occlusion technique

Insert 12-16Fr sheath that's 45cm length with a compliant balloon

Balloon vs clamp for proximal control on intraop mortality

19% vs 34% in hospital mortality is however the same

Anesthetic type in mortality

Local better than general (IMPROVE)

ABI vs AUI in RAAA mortality

similar outcome

Cell save: pRBC ratio that's been shown to reduce mortality

Ratio > 1 more cell saver better

Venous anomaly in OAAA encountered

1) Retroaortic renal vein 1-3% 2) Circum aortic renal vein 0.5-1.5% 3) left sided IVC 0.15-0.5% 4) Duplicate IVC 0.4-3%

Mannitol dose

3-5 ml/kg

Rate of unclosable abd after RAAA

25-30%

Local complications after RAAA treatment

1) Coagulopathy and bleed 12-14% 2) access bleed/thrombosis 7-10% 3) colon ischemia 26% Gr 1-2; 10% Gr3 4) Abdominal compartment syndrome 8% total; 21% in EVAR 5) Spinal ischemia: 1.2% OSR, 0.5-11.5 EVAR

Risk of ischemic colitis in different types of open repair and EVAR

OSR 38% Tube 4% ABI 2.7% ABF 22% EVAR 23%

Abdominal compartment syndrome definition and when to treat

> 20 mmhg with organ failure | Decompress if > 25 mmHg

How to measure abdominal compartment pressure

Instill 50-100 ml fluid then zero at pubic symphysis

Systemic complication

1) Cardiac arrest 20%; mortality 81-100% 2) MI 15-20%; mortality 17-66% 3) CHF 20%; mortality 40% 4) troponitis 55%; mortality 40.3% 5) respiratory: 35.9% OSR, 28.5% EVAR 6) trach 9.9% OSR; 4.6% EVAR 7) renal complication 26-45%; dialysis 11-40%; mortality 76-89% 8) liver complication mortality 83%

Renal failure post RAAA repair for OSR vs EVAR in NIS and medicare

NIS: 19.6% OSR vs 12.1% EVAR MEDICARE: 45.4% OSR vs 33.4% EVAR

Multiorgan failure rate in OSR for elective, urgent and rupture

3.8% elective 38% urgent 64% rupture

Mortality after multiorgan failure in ruptures

64-93%

Theory of multiorgan failure in ruptures

Two-hit hypothesis | Neutrophil oxidative bursts

US National discharge database, NIS and MEDICARE on EVAR vs OSR for ruptures

30d mortality benefit 13-14% better in EVAR

MEDICARE study 2001-2008 key findings

1) mortality 33.8% EVAR vs 47.7% OSR 2) decrease complication EVAR except MI, HD, DVT 3) LOS 7 vs 14 days 4) dC home 22% higher in EVAR 5) longer term benefit of EVAR present up to 4 years

Trends in MEDICARE data from 2001 to 2008

1) increase EVAR use 6-31% 2) EVAR mortality 46% to 27% 3) OSR mortality 44.7% to 40% 4) % of RAAA unrepaired dropped

NIS data 2005-2009 on 21206 patients

1) EVAR more common at teaching hospitals 2) non-operative management higher in rural hospitals 3) > age 80 increase non-operation and less OSR 4) EVAR pt have more CHF, CAD, DM, CKD 5) EVAR has reduced mortality and complications

NIS and UK hospital episode statistics comparison

1) Higher rates of repair in US 80.4% than UK 58.4% 2) OSR more in UK 91.5% than US 79.1% 3) UK OSR have less mortality 4) US EVAR have less mortality 5) UK dc home more; US dc to nursing facility 6) predictor of mortality: weekend admit, interhospital transfer, not at teaching hospital

Pilot study in 2002-2004 of 32 ruptures

feasibility study to determine if RCT can be done

AJAX key points

1) Amsterdam study 2) randomize after CTA for suitable for both groups 3) 2004-2011 4) 520 pt evaluated; 116 enrolled (22%) 5) mortality 21% EVAR; 25% OSR 6) death and severe complication at 30d: 42% EVAR; 47% OSR

IMPROVE key points

1) Clinical diagnosis and randomize before CT 2) mortality 35.4% EVAR vs 37.4% OSR 3) women mortality benefit from EVAR 37 vs 57% 4) patients who ultimately had EVAR has less mortality at 30d 25 vs 38% 5) evar had less ICU, increase DC home 6) cost the same

ECAR key points

1) french study 2) stable RAAA 3) 30d and 1 yr mortality same 30 vs 35 at 1 yr 4) EVAR benefit = less resp comp, blood transfusion and ICU

Metaanalysis of 3 RCT on ruptures

1) no mortality benefit at 1 year 2) EVAR has less LOC, pulm, renal and cost 3) mortality benefit in women

IMPROVE 3 YEAR key points

1) EVAR decrease mortality 42 vs 54% 2) decrease LOC 14.4 vs 20.5 3) increase DC to home 4) cost effective 5) every 10 mmhg increase in BP upon presentation improves 13% survival 6) local anes improve survival 4x 7) 28% reintervention at 3 year in each group and most within 3 months

Predictor of mortality

1) LOC on presentation 2) pre-op MI 3) CHF history 4) CKD history 5) advanced age 6) female 7) non-white 8) high APACHE II score

VSGNE RAAA independent predictors of death

1) Age > 76 2) preop MI 3) LOC 4) suprarenal clamp

Post-op outcome factors

1) pre-induction SBP 2) pre-op Cr 3) intraop urine output 4) site of cross clamp 5) duration of cross clamp 6) intraop MI, resp, renal coagulopathy 7) dialysis post-op 8) volume of blood needed

Studies that looked at late survival 5 year elective vs rupture

Canadian aneurysm study: RAAA 53% vs 71% elective US VA data: 54 vs 69% Mayo: 64 vs 74%

VQI on in hospital mortality and 1-5 year mortality

In hospital 23% EVAR vs 35% OSR | 1-5 year no difference

Post-EVAR rupture risk

1.4% at 28 months mostly due to Type 1 endoleak 46.8% had attempted repair of endoleak

Chapter 74 - Ruptured AAA Flashcards

(66 cards)