Chapter 74 - Ruptured AAA Flashcards
Causes of symptoms in non-ruptured AAA
1) Acute expansion
2) Intramural hemorrhage
3) Wall degeneration
4) bleeding into thrombus
Preludes rupture
Bahnson 1953
First successful RAAA repair with homograft
Cooley + DeBakey 1954
Treated 6 patients with 50% survival
Hopkinson 1994
First EVAR in rupture
Trend of death due to RAAA over time
decrease mortality
Male mortality decreased more than female
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
Mortality post-rupture surgery
31.6%
US 41.6%
UK 41.8%
Percent of ruptures offered repair in US vs UK
80% US
58% UK
Post-op mortality causes
1) hemorrhagic shock
2) reperfusion injury
Wall strength in pressure measurements
Normal = 121 N/cm2 AAA = 65 N/cm2
Laplace’s Law
Tension proportional to radius and pressure
Hot spots in wall weakness
localized MMP activity with local weakening
Typical weakest spot in aortic aneurysm
Posterior wall
Martin 1965 on theory of wall thrombus
Wall thrombus prevent nutrition transfer therefore weaker wall
Schurink on wall thrombus and pressure
Thrombus does not decrease pressure
Tested using transducers during OAAA
Vorp on wall thrombus
Causes local hypoxia resulting in
1) neovascularization
2) inflammation
3) wall thinning
4) increase collagenase –> less elastin and collagen
% of ruptures that occur at site of mural thrombus
80%
Classic triad of RAAA
1) pulsatile mass
2) hypotension
3) abdominal/back pain
9% in mis diagnosed group
34% in correctly diagnosed group
Rate of accurate diagnosis of RAAA upon first physician
23%
Rate of incorrect diagnosis of RAAA
16-60%
Common mis diagnosis of RAAA
1) renal colic
2) perforated viscus
3) diverticulitis
4) GI hemorrhage
5) ischemic bowel
US accuracy to identify RAAA
51%
Aortocaval fistula sign
1) new onset CHF
2) increase IJ pressure
3) loud new bruit/thrill
4) pulsatile mass
RAAA sign on plain X-RAY
1) large calcified wall 65%
2) loss of psoas shadow 75%
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
