Open AAA

 

Pre-op issues:

Assessment

Problems:

·      IHD, cardiomyopathy, HTN
Cardiac patient undergoing non-cardiac surgery

·      Smoking, COPD

·      T2DM

·      CKD

Investigations:

·      Blood: FBE, UEC, LFT, coag, HbA1c

·      Cardiac: ECG, TTE, ±stress test

Review:

·      PMU

·      Specialty team

Optimisation

Lifestyle:

·      Stop smoking

·      Diet

·      Exercise (not sure)

Medication to start:

·      Aspirin

·      Statin

Medications to withhold:

·      Antiplatelets (except aspirin)

·      Anticoagulants (± reversal)

·      ACE-inhibitor

·      Hypoglycaemics (SGLT 72h, metformin 48h, sulfonylurea 24h)

Discussion

Major risks:

·      AMI

·      Stroke

·      Renal failure

·      Spinal cord infarction

·      Death

Response:

·      Explore patient’s values

·      Stratify risk: RCRI, NSQIP, etc.

·      Discuss goals of care

·      Book ICU bed

 

Intra-op issues:

Aneurysm

Goals: prevent rupture

·      HR

·      SBP

Practice:

·      Opioid

·      Beta blocker

Bleeding

Preparation:

1.    Blood: cell salvage + cross-match 10 units

2.    Access: PIVC + RIC line + A-line + CVC + pump set

3.    Warming: upper + lower body air warmers + rapid fluid warmer

Monitoring:

·      Volume: PPV, IDC, ABG

·      Clotting: ABG + viscoelastic + plt + coags

·      Heat: nasal temp probe

Goals:

1.    Stop bleeding: surgery + permissive hypotension

2.    Promote clotting: reversal + products + TXA + calcium + heat

3.    Replace losses: 2L crystalloid + cell saver + bank (1:1:1 ratio)

4.    Preserve vital organs: mAP >50, PaO2 >100, pH >7.2, lactate <4

Clamping

Main things:

·      Communication ++

·      Preparation ++

·      Request slow clamping

↑↑Afterload / ↑↑Preload

·      proximity to heart

·      Risk of AMI, APO

·      Before: hypovolaemia + vasoconstriction (norad)

·      After: vasodilatation (GTN)

Ischaemia:

·      duration

·      Can’t do much about it

·      Turn off lower limb forced air warmer

Unclamping

Main things:

·      Communication ++

·      Preparation ++

·      Request slow un-clamping

↓↓Afterload / ↓↓Preload

·      proximity to heart

·      Risk of organ ischaemia

·      Before: euvolaemia + vasodilatation (GTN)

·      After: vasoconstriction (norad)

Reperfusion:

·      duration

·      Risk of myocardial depression, vasoplegia

·      Before: hyperventilation + CaCl infusion

·      After: vasoconstrictor (norad infusion) ± inotrope (adrenaline bolus)

·      Turn on lower limb forced air warmer

Renal protection

Risk factors:

·      Patient: CKD, heart failure, T2DM, renovascular disease

·      Surgery: recent contrast, long clamp time, renal artery disruption

·      Anaesthesia: hypoperfusion, nephrotoxins, massive transfusion

Preserve the vessels

·      Fenestrated graft

·      Re-anastomosis

Preserve perfusion pressure:

·      ↑mAP: volume + pressor

·      ↓CVP: cardiac function

Things that don’t work:

·      Dopamine (renal dose 1-3mcg/kg/min)

·      Mannitol

·      Frusemide

·      NAC

·      Methylprednisolone

Spinal protection

Risk factors:

·      Patient: not sure

·      Surgery: affects lumbar arteries, artery of Adamkiewicz

·      Anaesthesia: hypoperfusion

Monitoring:

·      MEP

·      SSEP

Preserve the vessels:

·      Fenestrated graft

·      Re-anastomosis

Preserve perfusion pressure:

·      ↑mAP: volume + pressor

·      ↓CVP: cardiac function

·      ↓CSF pressure: insert lumbar drain pre-op if high risk

 

Post-op issues:

 

Pain

Neuraxial:

·      ±Thoracic epidural

·      ±ITM

Regional:

·      Bilateral rectus sheath catheters

Parenteral:

·      Ketamine infusion

·      Opioid infusion in ICU -> PCA on the ward

Monitoring:

·      APS review q12h

·      Test platelets + coags before removal of epidural catheter

Organ failure

Mitigation and prevention:

·      Vasoplegia: CVC + noradrenaline

·      Renal failure: fluid status + perfusion pressure

·      Coagulopathy: viscoelastic + warmth + products + adjuvants

·      Liver failure: volume + pressor

·      Spinal cord ischaemia: ±lumbar drain

 

 

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