ANAESTHESIA FOR VASCULAR SURGERY

OUTLINE๏ Preoperative Assessment

๏ Carotid endarterectomy

๏ Abdominal aortic surgery

๏ Endovascular surgery

๏ Peripheral vascular surgery

๏ Lower limb amputation

๏ Questions and Answers

PREOPERATIVE ASSESSMENT๏ Co-existing co-morbidities๏ Coronary artery disease – 80%๏ Diabetes – 20%๏ Hypertension – 50%๏ Smoker๏ COPD – 50%๏ Carotid disease – CVA, TIA๏ Renal impairment – 30%๏ CCF – 10%

๏ If surgical site is sclerotic so are other areas!

OUTCOME IN HEART FAILURE PATIENTS AFTER MAJOR NON CARDIAC SURGERY HERNANDEZ ET AL. JOURNAL OF AMERICAN COLLEGE OF CARDIOLOGY

2004;44:1446-53.pa

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25Heart failureCoronary artery diseaseControl

PREOPERATIVE ASSESSMENT๏ Significant MDT challenge

๏ Focussed preop assessment

๏ Appropriate investigations

๏ Role of beta blockers and statins.

๏ Cardiology input - revascularisation

๏ Accurately determine risk

๏ EVAR or open.

RISK INDICATORS ๏ Revised cardiac risk index

๏ CVA

๏ Heart failure

๏ Ischaemic heart disease

๏ High risk surgery

๏ Insulin therapy

๏ Renal impairment

Points Risk

0 0.4-0.5%

1 0.9-1.3

2 4-7%

3+ 9-11%

INVESTIGATIONS

๏ Routine bloods and investigations are no use.

๏ Biomarkers

๏ Echo

๏ DSE/Thallium

๏ Measurement of functional capacity

MORBIDITY

Non cardiac surgery

MACE 13.7 %

30 day MI rate 5%

Cardiac death 1.6%

65.3% had no clinical

symptoms

11.6% mortality at 30

daysEffects of extended release metoprolol succinate in patients undergoing non cardiac surgery (POISE trial): a randomised control trial. Lancet Volume 371, issue 9627 pages 1839-1847

BIOMARKERS

75

Overall it appears that an elevated preoperative BNP or NT pro BNP confers increased

risk in the peri-operative period in both the vascular and non-vascular population. What

remains unclear however is the optimal cut off for these assays, which if any is superior,

and whether the cut off varies depending on the type and urgency of the surgery. The risk

associated with raised plasma levels of these assays also appears to be variable, perhaps

partly reflecting the varying end points and definitions of MACE seen within the

different studies, and the differing time periods over which the populations were studied.

The results of a meta analysis from 2009203 show the strong signal that these biomarkers

elude to (table 2.7), and overall the NPV for normal values of BNP (<100 pg.ml-1) and

NT-proBNP (<300 pg.ml-1) are high at 99%, and hence the measurement of these

biomarkers would provide a superior and simple test for identifying patients who would

not need further investigation.

Odds ratio (95% CI)

BNP NT -proBNP Overall

Short term MACE 25.45 (12.46-51.97) 15.65 (10.39-23.57) 19.77 (13.18-29.65)

Longer term MACE 11.18 (3.56-35.07) 11.18 (3.56-35.07)

Short term all cause

mortality

17.70 (3.11-100.80) 5.11 (1.46-17.88) 7.81 (2.83-21.58)

Longer term all

cause mortality

5.37 (2.51-11.51) 4.57 (2.04-10.20) 4.72 (2.99-7.46)

Short term cardiac

mortality

39.07 (11.63-

131.25)

14.09 (2.07-96.00) 23.88 (9.43-60.43)

Table 2.8 Odds ratios (95% CI) for short and long term major adverse cardiac events

(MACE), short and long term all cause mortality, and short term cardiac mortality for a

raised BNP, NT-proBNP and for both combined.

Prognostic value of BNP in non cardiac surgery. A meta analysis.Ryding et al. Anesthesiology 2009;111:311-9

TROPONIN

COMMENTIn this international prospectivecohort study of 15 133 patients whowere at least 45 years of age andunderwent noncardiac surgery thatrequired hospital admission, multi-variable analysis demonstrated thatfourth-generation peak TnT thresh-olds of 0.02 ng/mL, 0.03 ng/mL, and0.30 ng/mL independently predicted30-day mortality. Peak TnT valuesafter noncardiac surgery proved thestrongest predictors of 30-day mor-tality, and the population attributablerisk analysis suggested elevated TnTmeasurements after surgery mayexplain 41.8% of the deaths. Basedon the identified peak TnT values,

there were marked increases in theabsolute risk of 30-day mortality (ie,1.0% for a TnT value !0.01 ng/mL;4.0% for a value of 0.02 ng/mL; 9.3%for a value of 0.03-0.29 ng/mL; and16.9% for a value "0.30 ng/mL);11.6% of patients had a prognosti-cally relevant peak TnT value of atleast 0.02 ng/mL. The higher thepeak TnT value, the shorter themedian time to death. Our net reclas-sification improvement analysis dem-onstrated that monitoring TnT val-ues for the first 3 days after surgerysubstantially improved 30-day mor-tality risk stratification comparedwith assessment limited to preopera-tive risk factors.

Strengths and LimitationsStrengths of this study include the largesample of patients undergoing noncar-diac surgery from 8 countries in 5 con-tinents. Our results were consistentacross sites for the TnT thresholds, sug-gesting they are relevant to contempo-rary surgery worldwide. All patients hadthe same fourth-generation TnT assaymeasured after surgery. A total of 99.7%of the patients completed the 30-day fol-low-up. We had complete data on the24 preoperative variables that we evalu-ated. The model that included the peakTnT measurement demonstrated gooddiscrimination and calibration.

Rather than evaluating predeter-mined values, we statistically identifiedprognostically relevant TnT thresh-olds. Thresholds based on 99th percen-tiles or coefficients of variation of lessthan 10%, although commonly used, arearbitrary. Studies that demonstrate worseprognosis above these thresholds do notconfirm these thresholds are where riskis actually changing. Such results may bedriven by the poor outcomes of pa-tients with TnT measurements substan-tially above these thresholds. Further,some patients with troponin values im-mediately below these thresholds mayhave poor outcomes, but their signal mayget washed out by the larger patientpopulation with even lower troponin val-ues who have few or no events. It is forthis reason that we believe statistically

Figure 2. Kaplan-Meier Estimates of 30-Day Mortality Based on Peak Troponin T Values

0.20

0.15

0.10

0.05

0.0

Peak troponin T, ng/mLNo. at risk

Peak troponin T, ng/mL

≥0.30

≤0.01

0.03-0.29

0.02

0 5 10 15 20 25 30

≥0.30 142 136 129 127 121 118 1170.03-0.29 1121 1103 1075 1058 1036 1030 10180.02 494 492 489 485 480 477 473≤0.01 13 376 13 348 13 300 13 271 13 250 13 230 13 209

Days After Surgery

Cum

ulat

ive

Haz

ard

Table 2. Net Reclassification Improvement of Predicted Probability of 30-Day Mortality With the Model That Included the Peak TnTMeasurement Compared With the Model Based Only on the Preoperative Risk Factorsa

Models for 30-Day Probability of Death

Preoperative RiskFactors Only

Includes Peak TnT Measurement

Died, No. Survived, No.

#1% 1%-5% $5%-10% $10% #1% 1%-5% $5%-10% $10%

#1% 25 16 0 0 8014 496 15 01%-5% 10 68 21 22 1488 3398 290 183$5%-10% 0 20 13 30 0 419 148 133$10% 0 1 5 51 0 35 92 140Abbreviation: TnT, troponin T.aThe number of patients who were reclassified to a higher risk category based on the model that included the peak TnT measurement compared with the model that only

included preoperative risk factors was 89 among the patients who died and 1117 among those who survived. The number of patients who were reclassified to a lower riskcategory based on the model that included the peak TnT measurement compared with the model that only included preoperative risk factors was 36 among the patients whodied and 2034 among those who survived. Among the patients who died, the percentage correctly reclassified to a higher risk category when both models were comparedwas 89 minus 36, divided by the total number of patients who died (282), which equals 18.8%. Among the patients who survived, the percentage correctly reclassified to alower risk category when both models were compared was 2034 minus 1117, divided by the total number of patients who survived (14 851), which equals 6.2%. The netreclassification improvement is the sum of the percentages of correctly reclassified individuals who did and did not survive (ie, 18.8%%6.2%=25.0% [95% CI, 17.2%-32.8%]P#.001).

POSTOPERATIVE TROPONIN LEVELS AND 30-DAY MORTALITY

2300 JAMA, June 6, 2012—Vol 307, No. 21 ©2012 American Medical Association. All rights reserved.Corrected on June 5, 2012

Downloaded From: https://jamanetwork.com/ by a University of Leeds User on 07/10/2016

ECHOCARDIOGRAPHY Risk Group Relative risk Number need

to harm

Overall 1.01 (0.92-1.11)

High risk (RCRI>3)

1.0 (0.87-1.13)

Intermediate risk

1.10 (1.02-1.18)

116

Low risk (RCRI 0)

1.44(1.14-1.82)

163

Wijeysundera.BMJ 2011;342:d3695

DYNAMIC MEASURES OF CARDIAC PERFORMANCE

Test Likelihood ratio for a positive event

Likelihod ratio for a negative event

Stress echocardiography 4.09 0.23

Thallium Scanning 1.83 0.44

Moderate to large defect 8.35

FRIEND OR FOE?

Wijeysundra. BMJ 2010Cardiac stress testing

Lindenauer. NEJM 2005Beta blockers

BETA BLOCKERS AND STATINS

CARDIOPULMONARY EXERCISE TESTING DYNAMIC ASSESSMENT OF CARDIAC PERFORMANCE

๏ GRADED EXERCISE TEST

๏ MEASUREMENT OF OXYGEN CONSUMPTION.

๏ PEAK OXYGEN CONSUMPTION

๏ ANAEROBIC THRESHOLD

๏ VENTILATORY EQUIVALENTS

๏ CARDIAC PERFORMANCE

CPET AAA REPAIR

CPET AAA REPAIR

Step 4Functional Capacity

Number of patients

AT < 11 AT > 11

RCRI present(32%)

184 87

RCRI absent(68%) 273 303

CPET for all ?

Are LRCRI clinical risk factors present ??

Yes No

Class IIa recommendation

Class I recommendation

Step 4Functional Capacity

Deaths

AT < 11 AT > 11

RCRI present(32%) 7 / 184 1 / 87

RCRI absent(68%)

9 / 273 1/ 303

CPET for all ?

0.5%

3.2%3.7%

NoYes

Are LRCRI clinical risk factors present ?? 32% of patients!

CAROTID ENDARTERECTOMY

CAROTID ENDARTERECTOMY๏ Stroke 3rd commonest cause of mortality in Western world

๏ CEA performed as a preventative procedure to prevent disabling or fatal stroke

๏ Risk of major stroke is greatest in first few days after a TIA or minor stroke

๏ Operate with > 50% stenosis and symptomatic and should be done within 2 weeks (often sooner - 48 hours)

๏ 5000 procedure last year

๏ Peri-operative mortality and major stroke risk 2%

ANAESTHETIC CONSIDERATIONS ๏ High risk procedure

๏ Cardiovascular instability very common๏ Impaired auto-regulation of arterial

pressure

๏ Reduced baroreceptor sensitivity due to carotid atherosclerosis

๏ Old age

๏ Anti-hypertensive medication/Diabetes

๏ TIVA becoming increasingly popular๏ Rapid control of changes

in BP

๏ Smooth emergence with less coughing

๏ Rapid awakening for neurological assessment

ANAESTHETIC OPTIONS ๏ All require invasive BP monitoring

๏ GA +/- superficial cervical plexus block๏ Invasive arterial monitoring๏ TIVA or inhalational + remifentanil๏ Secure airway with ET tube

๏ Regional anaesthetic๏ Superficial cervical plexus block๏ Deep cervical plexus block๏ +/- Supplementation of submandibular branches of the trigeminal nerve – discomfort caused by

surgical retraction

Nationally 52% under GA

ANAESTHETIC OPTIONS ๏ GALA Trial - 3500 patients

๏ Primary outcome – Stroke, MI, or death at 30 days after surgery

๏ No significant difference

๏ Secondary outcome – Stroke, MI, death at 1 year , quality of life and length of hospital stay

๏ Stroke and MI at 1 year reduced in the LA group

GENERAL ANAESTHESIA

Advantages

• Patient preference/immobility • Secured airway• Controlled ventilation and CO2

• Potential for neuro-protection• No time constraints• Maintenance of cerebral auto-

regulation with low dose inhalational /TIVA

Disadvantages

• Lack of direct neurological monitoring

• Intra-operative hypotension• Post-operative hypertension• Increased shunt rate• Delayed recovery may mask

neurological complications

BLOOD PRESSURE CONTROL

๏ SAP > 220mmHg or < 90mmHg in about 10% patients

๏ Arterial baroreflex impaired

๏ Cross clamping

๏ Carotid sinus anaesthesia

๏ Avoid hypotension during clamping and hypertension afterwards.

๏ At time of cross clamping = BP 20% of baseline BP

๏ After cross clamping = maintain BP above that at time of cross clamping

๏ Do NOT treat post clamping hypertension without informing surgeon

ASSESSMENT OF CEREBRAL PERFUSION

๏ Gold standard – awake patient

๏ Stump pressure

๏ Transcranial doppler

๏ Near infra-red spectroscopy (NIRS)/cerebral oximetry

๏ EEG

๏ Somatosensory evoked potentials

SHUNTING

๏ All undergoing GA

๏ Reduced LOC in patients during an awake procedure

SHUNTING๏ Air or plaque embolism

๏ Carotid dissection

๏ Intimal tear

๏ Post shunt stenosis

๏ Nerve injury

๏ Haematoma

๏ Infection

PERIOPERATIVE COMPLICATIONS ๏ Cerebral hyper-perfusion syndrome๏ Patients at risk = high grade carotid stenosis๏ Occurs in 1% of patients after CEA๏ Present 2-7 days post-op๏ Due to impaired cerebral auto-regulation๏ Symptoms:๏ Ipsilateral headache๏ Focal seizures๏ Neurological deficit๏ Intracerebral haemorrhage

PERIOPERATIVE COMPLICATIONS ๏ Hypertension๏ Damage or LA to carotid sinus

๏ Hypotension๏ Hyper-stimulation of baroreceptors following plaque removal

๏ Stroke - 2%๏ MI - 1%๏ Airway compromise – oedema/haematoma 2.8%๏ Cranial nerve injury 1.6%๏ Damage to carotid body = reduced ventilatory response

QUESTION: MARCH 2016A 56-year-old man is listed for carotid endarterectomy 10 days after suffering a cerebrovascular accident.

a) What are the advantages (4 marks) and disadvantages (4 marks) of performing the procedure under regional anaesthesia?

b) What local or regional anaesthetic techniques may be used? (3 marks)

c) How can his risk of perioperative cerebrovascular accident be minimised? (6 marks)

d) Following this procedure what other specific postoperative complications may occur? (3 marks)

A) WHAT ARE THE ADVANTAGES (4 MARKS) AND DISADVANTAGES (4 MARKS) OF PERFORMING THE PROCEDURE UNDER REGIONAL ANAESTHESIA?

Advantages

• Real time neurological monitoring• Avoids risks of airway intervention• Reduced shunt rate• Avoids need for cerebral monitoring• Reduced hospital stay• Allows arterial closure at normal

arterial pressure – may reduce risk of haematoma

Disadvantages

• Risks of blocks• Requires co-operative patient• Restricted access to airway during

surgery• Risk of need to convert to GA

B) WHAT LOCAL OR REGIONAL ANAESTHETIC TECHNIQUES MAY BE USED? (3 MARKS)

๏ Local infiltration

๏ Cervical epidural (not widely performed in UK)

๏ Superficial cervical plexus block

๏ Deep cervical plexus block

๏ Deep cervical and superficial cervical plexus block

๏ +/- Supplementation of submandibular branches of the trigeminal nerve (discomfort caused by surgical retraction)

C) HOW CAN HIS RISK OF PERIOPERATIVE CEREBROVASCULAR ACCIDENT BE MINIMISED? (6 MARKS)

๏ Use of antiplatelet and anticoagulation drugs

๏ All patients should be taking aspirin before surgery

๏ Some are prescribed additional antiplatelet e.g. clopidogrel

๏ Heparin (usually 5000 IU i.v.) is administered just before carotid artery cross-clamping

๏ Avoidance of cardiovascular instability (especially hypotension or hypertension)

๏ Invasive arterial line monitoring

๏ Control of BP - maintain arterial pressure <170 mm Hg and ideally within 20% of the patient’s baseline during surgery

๏ Monitor for cerebral hyper-perfusion syndrome

D) FOLLOWING THIS PROCEDURE WHAT OTHER SPECIFIC POSTOPERATIVE COMPLICATIONS MAY OCCUR? (3 MARKS)

๏ Airway compromise – secondary to wound haematoma formation due to untreated post-operative hypertension

๏ Cerebrovascular accident

๏ Cerebral hyper-perfusion syndrome

๏ Cranial nerve injury - vagus, glossopharyngeal, hypoglossal

๏ Myocardial infarction

๏ Restenosis

QUESTION: MAY 2006/MARCH 2011

a. Briefly describe your technique for performing a deep cervical plexus block for carotid endarterectomy under local anaesthesia. (7 marks)

b. List the complications of a deep cervical plexus block. (6 marks)

c. A carotid endarterectomy is being performed using a superficial cervical plexus block. A few minutes after clamping the carotid artery the patient becomes unresponsive to verbal command. Describe your management of this situation. (7 marks)

A) BRIEFLY DESCRIBE YOUR TECHNIQUE FOR PERFORMING A DEEP CERVICAL PLEXUS BLOCK FOR CAROTID ENDARTERECTOMY UNDER

LOCAL ANAESTHESIA. (7 MARKS)

๏ The Block

๏ Patient turns head to opposite side to be blocked

๏ Landmark = anterior rami of C2-4

๏ Draw a line 1cm below the mastoid process to the anterior tubercle of the transverse process of C6 (Chassaignac’s tubercule) at the level of the cricoid cartilage

A) BRIEFLY DESCRIBE YOUR TECHNIQUE FOR PERFORMING A DEEP CERVICAL PLEXUS BLOCK FOR CAROTID ENDARTERECTOMY UNDER

LOCAL ANAESTHESIA. (7 MARKS)

๏ Intervals of 1.5cm below the mastoid process on this line indicate the transverse processes of C2-4

๏ The needle is directed caudally and medially until it reaches the transverse process and then withdrawn slightly

B) LIST THE COMPLICATIONS OF A DEEP CERVICAL PLEXUS BLOCK. (6 MARKS)

๏ Intravascular injection

๏ Vertebral artery puncture

๏ Intrathecal injection – epidural/subarachnoid

๏ Spinal cord injury

๏ Local anaesthetic toxicity

๏ Bilateral spread

๏ Pneumothorax

๏ Side effects:

๏ Phrenic nerve block (runs below the mastoid process)

๏ Horner’s syndrome (Stellate ganglion block)

๏ Recurrent laryngeal nerve block

๏ Hypoglossal nerve block

C) A CAROTID ENDARTERECTOMY IS BEING PERFORMED USING A SUPERFICIAL CERVICAL PLEXUS BLOCK. A FEW MINUTES AFTER CLAMPING THE CAROTID ARTERY

THE PATIENT BECOMES UNRESPONSIVE TO VERBAL COMMAND. DESCRIBE YOUR MANAGEMENT OF THIS SITUATION. (7 MARKS)

๏ Inform the surgeon - main aim is to improve cerebral blood flow as soon as possible

๏ ABC approach๏ If under LA, then convert to general anaesthesia

๏ Cardiostable induction and avoidance of fluctuation in BP

๏ Secure airway with endo-tracheal tube

๏ Options to increase blood flow:๏ Shunt to divert blood flow above the level of the clamp (performed by

surgeon)

๏ Increase blood pressure and rely on collateral circulation

OPEN AAA REPAIR

BACKGROUND ๏ 5000 cases per annum

๏ Operate at over 5.5cm

๏ Incidence 5-10%

๏ 75% over 66

๏ Mostly male

๏ Multiple co morbidities

๏ LOS 8 days

๏ Mortality 3.2%

๏ Cardiac compilation 5%

๏ Resp 12%

๏ Renal failure 4%

๏ limb ischaemia 3%

๏ 25% have a complication overall

ABDOMINAL AORTIC ANEURYSM QUALITY IMPROVEMENT PROGRAMME - AAAQIP

๏ All patients should undergo standard preoperative assessment and risk scoring, including cardiac, respiratory, renal, diabetes, peripheral vascular disease, as well as CT angiography to determine their suitability for EVAR

๏ All patients should be seen in pre-assessment by an anaesthetist with experience in elective vascular anaesthesia

๏ Ideally, a vascular anaesthetist should also be involved to consider fitness issues that may affect whether open repair or EVAR is offered

๏ All elective procedures should be reviewed in MDT that includes surgeon, radiologist and anaesthetist

SURGERY - CROSS CLAMPING ๏ Physiological effects depend on:

๏ Level of cross clamp (Suprarenal >>> infra-renal

๏ Length of clamp application

๏ Preoperative left ventricular function and physiological reserve

๏ Degree of coronary artery disease

๏ Degree of peri-aortic collaterallisation

๏ Blood volume and distribution

๏ Activation of sympathetic nervous system

๏ Anaesthetic agents and techniques

CLAMP

๏ Increase SVR

๏ Increase preload

๏ Increase contractility

CLAMP ON ๏ Increased sympathetic stimulation

๏ Increased coronary perfusion/blood flow

๏ Reduction in distal arterial blood supply

๏ Leads to a reduction in the return of blood to the venous system

๏ Blood redistributed to the major central veins๏ Increase in CVP and PCWP

INTERVENTIONS๏ Vasodilators

๏ GTN = reduced preload๏ Sodium nitroprusside = reduced afterload๏ Calcium channel blockers – magnesium

๏ Epidural analgesia

๏ Reduces sympathetic response to clamping๏ Increased splanchnic venous capacitance๏ Increased myocardial oxygen supply and decreased demand

๏ Volatile anaesthetic agents

๏ Decrease aortic pressure

CLAMP - RENAL INJURY ๏ Depends on duration and level of cross clamp application๏ Most effect with suprarenal

๏ Need to maintain perfusion pressure to the kidneys

๏ Main priority = maintenance of adequate extracellular fluid volume intra and post operatively

๏ Renal protection via:๏ Mannitol๏ Furosemide๏ Dopamine

CLAMP SPINAL CORD INJURY ๏ Spinal Cord Effect

๏ Perfusion pressure = MAP – CFS pressure

๏ Reduced anterior spinal artery pressure

๏ Venous engorgement

๏ Potential damage to collateral blood supply – Artery of Adamkowitz (T9-T12)

๏ Risk of neurological damage or paraplegia (40%)

INTERVENTIONS

๏ Surgical techniques

๏ Maintaining adequate blood pressure

๏ CSF lumbar drain

๏ Cooling techniques

๏ Ischaemic preconditioning

๏ Free radical scavenging

CLAMP OTHER - EFFECTS๏ Effect on Viscera

๏ Visceral ishcaemia (1-10%)

๏ Due to reduced or altered blood flow

๏ Patient factors = hypovolaemia, cardiac arrhythmia, reduced CO

๏ Surgical factors = emboli, thrombosis

๏ Effect on Coagulation

๏ Coagulopathy – coagulation factor consumption and activation of fibrinolytic pathways

๏ Haemorrhage

CLAMP OTHER - EFFECTS

๏ No blood flow to lower limb leads to:

๏ Reduced total body oxygen consumption and extraction

๏ Increased mixed venous oxygen saturation

๏ Accumulation of vasoactive metabolites

๏ Anaerobic metabolism

๏ Lactic acidosis

CLAMP OFF๏ Cardiovascular Effect

๏ Sudden reduction in afterload (70-80%)๏ Sudden reduction in preload - CO drops๏ Severe hypotension

๏ Sequestration of blood in the lower half of the body

๏ Ischaemia-reperfusion injury

๏ Vasodilation effect of anaerobic metabolites

๏ Reduced coronary blood flow and LVEDV๏ Hyperkalaemia - significant arrhythmias/cardiac arrest

CLAMP OFF๏ Metabolic effect

๏ Transient increase in:๏ CO2

๏ Oxygen consumption - mixed venous desaturation

๏ Metabolites from ischaemic tissue๏ Vasodilatation๏ Myocardial depression๏ Lactic acidosis

INTERVENTIONS๏ Preparation should start 10 minutes before unclamping

๏ Fluid administration to ensure adequate filling

๏ Vasoconstrictor drugs – phenylephrine, metaraminal, noradrenaline, adrenaline

๏ Reduce inhalational anaesthetic agent

๏ Hyperventilate to reduce PCO2

๏ Re-apply cross clamp for severe hypotension

๏ Consider bicarbonate for severe acidosis

RUPTURED AAA

CHALLENGES

๏ Mortality about 35%

๏ No benefit from EVAR (IMPROVE trial)

๏ Contained leak - tamponade

๏ Pain - sympathetic drive

๏ Hypotensive and shocked - avoid excess fluid admin

๏ Clench until clamp on

EVAR

EVAR๏ Increasingly popular - 60%

๏ Performed in interventional radiology suite

๏ Suitability depends on:

๏ Morphological features as assessed by 3D CT reconstruction

๏ Proximal neck – length, diameter, presence of thrombus, angle

๏ Distal landing zone – length and diameter

๏ Calibre, tortuosity of vessel

๏ Presence of aneurysms or thrombus in iliac arteries/access vessels

BENEFITS ๏ Avoidance of GA

๏ Less physiological disturbance

๏ Reduced blood loss

๏ Less pain

๏ Reduced length of ICU stay

๏ Reduced length of hospital stay

๏ Specific for infrarenal aneurysm

๏ Reduced procedural time

RISKS

๏ Longevity of grafts unknown

๏ Graft migration

๏ Endoleaks

๏ lifelong surveillance and risk of solid organ tumour.

ENDOLEAKS

EVAR TRIALS๏ EVAR 1

๏ Reduced 30 day operative mortality by 1/3

๏ No decrease in long term all cause mortality at 4 years

๏ Increased re-interventions and complications

๏ Same quality of life as open

๏ EVAR 2

๏ No long term survival benefit Vs surveillance in patients unfit for open repair

๏ 9% 30 day operative mortality in these patients

๏ IMPROVE

ANAESTHETIC OPTIONS๏ Local๏ Regional – CSE, epidural

๏ General

๏ EVAR can be an option for a ruptured AAA – only under LA

๏ Large bore IV access - right arm

๏ Invasive arterial monitoring – right arm

๏ Left arm and groins used for surgical access๏ Beware - potential for major blood loss and need for transfusion

COMPLICATIONS

Immediate Long term

• Failed deployment –conversion to GA

• Arterial rupture• Arterial dissection• Embolisation• Ischaemia of:

o Spinal cordo Kidneyso Bowelo Legs

• Endoleak• Infection• Graft migration• Delayed AAA rupture

QUESTION: MARCH 2012A 79-year-old patient presents with a leaking abdominal aortic aneurysm. The vascular surgery/radiology team decide to undertake an endovascular aneurysm repair (EVAR) procedure.

What are the main preoperative anaesthetic considerations for this procedure? (11 marks)

Describe options for providing anaesthesia for this case and give the advantages/disadvantages of each. (9 marks)

WHAT ARE THE MAIN PREOPERATIVE ANAESTHETIC CONSIDERATIONS FOR THIS PROCEDURE? (11 MARKS)

๏ Emergency procedure๏ Senior support required๏ Organisational aspects: ๏ Inform theatres and radiologist๏ Mobilise theatre team, radiology team, radiologist, surgeon, anaesthetist๏ Mobilise patient to radiology suite without delay๏ Personnel to liaise with blood bank๏ Detected porter๏ Radiology suite: isolated and unfamiliar environment๏ Protective clothing: ๏ Prolonged exposure to x-ray beams ๏ Lines should be of sufficient length ๏ Patient not fasted

WHAT ARE THE MAIN PREOPERATIVE ANAESTHETIC CONSIDERATIONS FOR THIS PROCEDURE? (11 MARKS)

๏ Pre-operative assessment should be rapid and targeted

๏ Careful evaluation of associated co-existing medical conditions (cardiac, renal, respiratory and other vascular pathology/medication

๏ Limited time to optimise patient prior to surgery

๏ Risk of conversion to open

๏ Establish good IV access in the form of large bore cannula

๏ Take bloods for FBC, U&E’s and clotting

๏ Group and save and Cross-match

๏ Cell salvage and rapid infuser

๏ Patient maybe profoundly shocked ๏ Cautious resuscitation with IV fluids (need to maintain tamponade effect)๏ Cardiovascular stability regained on stent deployment๏ Direct arterial pressure monitoring is essential to monitor beat to beat variations in BP

especially during deployment of stent๏ Urinary catheterisation to monitor renal output๏ Procedure usually ~2hrs: risk of hypothermia๏ If pt is awake – may become extremely restless leading to conversion to GA๏ Heparin 5000 IU is administered after exposure of femoral arteries ๏ Sometime additional bolus or infusion is required๏ Will need HDU postoperatively

DESCRIBE OPTIONS FOR PROVIDING ANAESTHESIA FOR THIS CASE AND GIVE THE ADVANTAGES/DISADVANTAGES OF EACH. (9 MARKS)

Advantages

• Spontaneous ventilation preserving venous return

• Fewer respiratory complication• Avoid haemodynamic changes

associated with GA• Improved immediate postoperative

analgesia

Disadvantages

• Extensive groin dissection, or femoro–femoral bypass precludes LA alone

• Patient co-operation may be limited• Pain from retroperitoneal

haematoma, tourniquet or lower limb ischaemia can be problematic

• Trans-oesophagealechocardiography cannot be used

• Acid-base derangements following reperfusion difficult to manage in spontaneously breathing patient

Local anaesthesia

DESCRIBE OPTIONS FOR PROVIDING ANAESTHESIA FOR THIS CASE AND GIVE THE ADVANTAGES/DISADVANTAGES OF EACH. (9 MARKS)

General anaesthesia

Advantages

• Apnoea, induced hypotension and patient immobility during stent deployment more easily achieved

• Transoesophagealechocardiography can be used

• Rapid conversion to open repair if

required• Optimal surgical conditions• No time constraints

Disadvantages

• Loss of tamponade effect of abdominal muscle tone

• Potential for GA-induced cardiovascular collapse

PERIPHERAL VASCULAR SURGERY

BACKGROUND

๏ Mortality 2.7% for bypass

๏ Median LOS 8 days

๏ Co Morbidities๏ HTN 60%

๏ IHD 32%

๏ Diabetes 38%

๏ Lung and real diseases approx 14% each

PERIPHERAL BYPASS

๏ Long procedures

๏ No benefit from one type of anaesthesia.

๏ Consider an arterial line and ventilation

๏ Ischaemia reperfussion injury

๏ Cardiac complications - siilent

ANAESTHETIC AIMS ๏ Haemodynamic stability

๏ Tachycardia + hypertension or hypotension = risk of MI

๏ Normothermia๏ Hypothermia = increased O2 demand, vasoconstriction, MI, post-op discomfort, impaired peripheral perfusion

๏ Optimal perioperative fluid hydration๏ Hypovolaemia = impaired peripheral perfusion and post-op graft function

๏ Avoid anaemia

๏ Excellent analgesia ๏ To attenuate stress responses

LIMB AMPUTATION

BACKGROUND

๏ Below knee mortality 6.1%

๏ Above knee mortality 11.6%

๏ LOS 24 days

๏ Co morbidities - 60% diabetic, 60%, HTN 40% and heart failure 10%

๏ High incidence of complications

๏ Respiratory infection 7%

๏ Cardiac 5%

๏ Wound infection

๏ Stump breakdown

๏ Poor mobility

๏ Postoperative pain: 70% experience Phantom limb pain

NCEPOD REPORT 2014 - RECOMMENDATIONS

๏ Lower Limb Amputation – Working Together

๏ Clinical care pathways with MDT involvement๏ All diabetic patients should have a pre and post operative review by a specialist

diabetes team

๏ Patients should be optimised prior to surgery๏ Consultant vascular surgeon should be in theatre๏ Consultant anaesthetist present๏ Rehabilitation services should be in place

๏ Should be consultant led

NCEPOD REPORT 2014 - RECOMMENDATIONS

๏ NICE recommends nutritional assessment of all patients should be made within the first 48 hours of admission

๏ Introduction of a model for medical care of amputees

๏ Care bundle should be developed to ensure structured management of amputation patients

๏ Pre-operative assessment of pain by pain team

QUESTION You have been asked to anaesthetise a 65 year old gentleman for a below knee amputation

a) What are the potential risk reduction strategies that are used during pre-operative assessment? (7 marks)

b) What are the advantages and disadvantages of a regional technique for anaesthesia in this group of patients? (7 marks)

c) What were the key findings with regards to perioperative care of patients undergoing lower limb amputation in the recent NCEPOD report on lower limb amputation? (6 marks)

A) WHAT ARE THE POTENTIAL RISK REDUCTION STRATEGIES THAT ARE USED DURING PRE-OPERATIVE ASSESSMENT? (7 MARKS)

๏ Targeted but detailed assessment of past medical history and functional status๏ Cardiac symptoms may be masked due to limited mobility related to claudication, ulceration๏ Investigations should include:๏ FBC, U&Es, Clotting, Glucose๏ ECG, CXR๏ ECHO – if symptomatic๏ PFTs/ABG if clinically indicated๏ Continue pre-op beta-blockers, aspirin, diuretics and ACEI๏ Ensure good glycaemic control๏ HbA1C < 70๏ Use of insulin if required

A) WHAT ARE THE POTENTIAL RISK REDUCTION STRATEGIES THAT ARE USED DURING PRE-OPERATIVE ASSESSMENT? (7 MARKS)

๏ Maintain a Hb level 80-100g/L

๏ Withhold LMWH for an appropriate duration where CNB is being considered

๏ Omit full therapeutic anticoagulation for 24 hours before surgery

๏ Omit prophylactic anticoagulation for 12 hours before surgery๏ Omit clopidogrel for 7 days prior to surgery

๏ Avoid prolonged fasting periods

๏ Ensure adequate nutrition

๏ Appropriate IV fluid regime should be started pre-op to ensure adequate hydration and correction of electrolytes

A) WHAT ARE THE POTENTIAL RISK REDUCTION STRATEGIES THAT ARE USED DURING PRE-OPERATIVE ASSESSMENT? (7 MARKS)

๏ Pre-operative pain control

๏ Multimodal analgesia

๏ Agents for neuropathic pain

๏ Opioid analgesia

๏ Amputation should be undertaken within 48 hrs of decision๏ Should be preformed by senior surgeon experienced in lower limb amputations

๏ Consultant anaesthetist or senior trainee with appropriate supervision should be available

๏ Prophylactic antibiotics guided by local policy, given within 60 mins prior to surgery

B) WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF A REGIONAL TECHNIQUE FOR ANAESTHESIA IN THIS GROUP OF

PATIENTS? (7 MARKS)

Advantages

• Improved respiratory function post-operatively

• Attenuation of stress response to surgery

• Reduction in early post-operative cognitive dysfunction/delirium

• Compliance with medical therapy and functional recovery

Disadvantages

• Patient cooperation required• Contra-indicated in septic patients• Spinal/epidural haematoma if

abnormal clotting/anticoagulation not withheld for appropriate time period

• Hypotension and nausea• Nerve damage• Epidural abscess

WHAT WERE THE KEY FINDINGS WITH REGARDS TO PERIOPERATIVE CARE OF PATIENTS UNDERGOING LOWER LIMB AMPUTATION IN THE

RECENT NCEPOD REPORT ON LOWER LIMB AMPUTATION? (6 MARKS)

๏ Earlier review by a consultant vascular surgeon may have altered outcome

๏ Deficiencies in note keeping

๏ No formal vascular imaging performed

๏ Un-necessary delay in surgery

๏ Avoidance of amputation in some patients – poor judgement

๏ Poor pre-operative review by physio/diabetes nurse

๏ No pre-operative discussion of discharge/rehabilitation planning

๏ No named responsible coordinator

๏ Poor pre-operative care

WHAT WERE THE KEY FINDINGS WITH REGARDS TO PERIOPERATIVE CARE OF PATIENTS UNDERGOING LOWER LIMB AMPUTATION IN THE

RECENT NCEPOD REPORT ON LOWER LIMB AMPUTATION? (6 MARKS)

๏ Inappropriate seniority of person taking consent

๏ No MRSA screening in some patients

๏ Good level of anaesthetic support

๏ But deficiencies in record keeping

MTFRegarding aortic aneurysm:

a. Patients with an abdominal aortic aneurysm with a diameter >55mm should be offered surgical repair

b. In patients fit for either EVAR or open repair, EVAR has a lower 30-day post-operative mortality than open repair

c. In patients un-fit for open repair, EVAR demonstrates a lower long term mortality compared to non-operative measures

d. The majority of abdominal aortic aneurysms are supra-renal

e. During dissection of an abdominal aneurysm, blood dissects between the tunica media and tunica adventitia

MTFRegarding aortic aneurysm:

a. Patients with an abdominal aortic aneurysm with a diameter >55mm should be offered surgical repair

b. In patients fit for either EVAR or open repair, EVAR has a lower 30-day post-operative mortality than open repair

c. In patients un-fit for open repair, EVAR demonstrates a lower long term mortality compared to non-operative measures

d. The majority of abdominal aortic aneurysms are supra-renal

e. During dissection of an abdominal aneurysm, blood dissects between the tunica media and tunica adventitia

MTFA 78-year old patient for carotid endarterectomy has a deep cerivcal plexus block. What signs indicate the successive sympathetic blockade?

a.Meiosis

b.Exophthalmus

c.Tachycardia

d.Nasal stuffiness

e.Anhydrosis

MTFA 78-year old patient for carotid endarterectomy has a deep cerivcal plexus block. What signs indicate the successive sympathetic blockade?

a.Meiosis

b.Exophthalmus

c.Tachycardia

d.Nasal stuffiness

e.Anhydrosis

MTFConcerning abdominal aortic aneurysm

a.Elective repair is required when diameter reaches 4.5cm

b.Higher rates of survival are associated with ruptures that are retroperitoneal

c.When ruptured, aggressive fluid resuscitation is essential

d.Aortic cross-clamping results in increased afterload

e.Emergency repair has a 36% mortality in the UK

MTFConcerning abdominal aortic aneurysm

a.Elective repair is required when diameter reaches 4.5cm

b.Higher rates of survival are associated with ruptures that are retroperitoneal

c.When ruptured, aggressive fluid resuscitation is essential

d.Aortic cross-clamping results in increased afterload

e.Emergency repair has a 36% mortality in the UK

SBADuring an emergency repair of abdominal aortic aneurysm, your strategy to reduce the risk of post-operative renal impairment involves:

a.Maintaining an adequate extracellular fluid volume and perfusion pressure

b.A dose of 40mg frusemide just before the aortic clamp goes on

c.A dose of mannitol of 0.25mg/kg after induction

d.Dopamine at 3 mcg/kg/min

e.Maintaining a central venous pressure of 4-7mmHg

SBADuring an emergency repair of abdominal aortic aneurysm, your strategy to reduce the risk of post-operative renal impairment involves:

a.Maintaining an adequate extracellular fluid volume and perfusion pressure

b.A dose of 40mg frusemide just before the aortic clamp goes on

c.A dose of mannitol of 0.25mg/kg after induction

d.Dopamine at 3 mcg/kg/min

e.Maintaining a central venous pressure of 4-7mmHg

SBAA 75 year old man presents for an elective open AAA repair. Which of the following statements is most accurate?

a. 88% of patients presenting for elective AAA also have a >90% occlusion of their left anterior descending coronary artery

b. A major cause of death postoperatively is failure of the anastomosis between the descending aorta and graft

c. Elective AAA repair has approximately 5% mortality but this is raised to >15% in the presence of an S3 heart sound

d. If the patient is a smoker, then they should refrain from smoking at least 12 days before their operation

e. Arterial lines should be placed in the right radial artery to ensure consistent readings throughout the operation

SBAA 75 year old man presents for an elective open AAA repair. Which of the following statements is most accurate?

a. 88% of patients presenting for elective AAA also have a >90% occlusion of their left anterior descending coronary artery

b. A major cause of death postoperatively is failure of the anastomosis between the descending aorta and graft

c. Elective AAA repair has approximately 5% mortality but this is raised to >15% in the presence of an S3 heart sound

d. If the patient is a smoker, then they should refrain from smoking at least 12 days before their operation

e. Arterial lines should be placed in the right radial artery to ensure consistent readings throughout the operation

SBAYour are scheduled to anaesthetise a 78-year old gentleman for an endovacular repair in the radiology suite. Which of the following is the most appropriate statement?

a. The use of regional technique such as an epidural or CSE is associated with a reduced morbidity and mortality

b. Left radial arterial line is usually sited for beat-to-beat monitoring

c. Deployment of the graft in the aorta usually causes some discomfort if a regional anaesthetic technique has been used

d. Bleeding can still occur and the incidence of red cell transfusion is similar to elective open repair

e. Post operative renal dysfunction is not infrequent

SBAYour are scheduled to anaesthetise a 78-year old gentleman for an endovacular repair in the radiology suite. Which of the following is the most appropriate statement?

a. The use of regional technique such as an epidural or CSE is associated with a reduced morbidity and mortality

b. Left radial arterial line is usually sited for beat-to-beat monitoring

c. Deployment of the graft in the aorta usually causes some discomfort if a regional anaesthetic technique has been used

d. Bleeding can still occur and the incidence of red cell transfusion is similar to elective open repair

e. Post operative renal dysfunction is not infrequent

SBA

A 70 year old man is brought to A&E following a collapse at home. The paramedics gave him 1000ml of crystalloid and noticed a pulsating swelling in the abdomen. On arrival in A&E his BP is 100/60mmHg, HR 110/min, and GCS 15/15. The FAST scan was positive and a CT scan showed a leaking aneurysm. Which of the is NOT appropriate management?

a. Check NIBP in both arms

b. Good preoperative assessment

c. Administer IV fluids to restore BP

d. Administer IV fluids to aim for MAP of 90mmHg

e. Get blood products as soon as possible

SBA

A 70 year old man is brought to A&E following a collapse at home. The paramedics gave him 1000ml of crystalloid and noticed a pulsating swelling in the abdomen. On arrival in A&E his BP is 100/60mmHg, HR 110/min, and GCS 15/15. The FAST scan was positive and a CT scan showed a leaking aneurysm. Which of the is NOT appropriate management?

a. Check NIBP in both arms

b. Good preoperative assessment

c. Administer IV fluids to restore BP

d. Administer IV fluids to aim for MAP of 90mmHg

e. Get blood products as soon as possible

SUMMARY

๏ High risk patients

๏ Underlying principle remain the same

๏ Anaesthetic technique generally has little effect

๏ Physiological changes important