FRCA Notes

Hepatic Resection

The curriculum asks for knowledge of 'the principles of the peri-operative management of... pancreatic and liver resection'.

The CRQ on hepatic surgery from 2020 (50% pass rate) saw marks lost on parts requiring 'a more detailed knowledge of hepatic anaesthesia'.

Resources

  • The commonest indication for liver resection is to treat metastases arising from colorectal cancer
    • 20% of colorectal cancer patients have liver metastases at presentation, and a further 33% will subsequently develop them
    • Resection of liver metastases improves prognosis

Other indications

  • Primary hepatic malignancy
    • Hepatocellular carcinoma (80%)
    • Cholangiocarcinoma (20%)
  • Benign cysts or adenomas
  • Haemangiomas
  • Focal nodular hyperplasia
  • Donor component of living-donor liver transplant (partial hepatectomy)

Outcomes

  • Post-operative mortality is in the region of 2 - 3%
  • Post-operative morbidity remains high (20-50%)

Anatomy

  • The arrangement of the liver anatomy and blood supply allow it to be divided into eight functional segments
  • Each segment has separate portal & arterial blood supply, and venous drainage
  • This allows resection of one segment without affecting vascular supply to adjacent parenchyma

Technique

  • Open or minimally invasive techniques are possible
  • Minimally-invasive liver resection involves either laparoscopy or robotic techniques
  • Up to 70% of patients may be suitable for minimally invasive techniques
  • The rate of conversion to open procedure is as high as 20%
Advantages Disadvantages
Improved visualisation Difficulty communicating from console
Reduced venous bleeding during parenchymal transection
(tamponade effect from pneumoperitoneum)		 ↓ tactile feedback
↓ blood loss Inability to manually palpate liver
↓ post-operative pain Inability to obtain quick vascular control in unexpected bleeding
↓ wound infection rates Steep learning curve
Faster recovery and ↓ LOS Up-front and ongoing costs
Greater patient satisfaction
Fewer intra-abdominal adhesions

Phases

  • Resection generally involves four phases:
    1. Assessment
    2. Mobilisation
    3. Parenchymal transection
    4. Closure

  • It is important to keep CVP low (0-5mmHg) during the first three phases, as this leads to:
    • Less distended hepatic outflow allowing improved visualisation of structures
    • Easier mobilisation
    • Easier dissection of hepatic veins
    • Significantly less venous bleeding and reduced need for blood transfusion
    • An associated reduction in morbidity (10% vs. 22%) and mortality

Perioperative management of the patient undergoing hepatic resection


History and examination

  • Many patients are frail and deconditioned, from both the primary disease and treatment thereof
  • Identification and optimisation of comorbidities should occur:
    • Anaemia, thrombocytopaenia, coagulopathy due to chronic disease, malignancy or impaired synthetic liver/biliary function
    • Malnutrition; 7 days nutritional supplements and 2 x carbohydrate drinks prior to surgery (ERAS recommendation)
    • Obesity
    • Diabetes; of particular concern as it is associated with a higher mortality in hepatic resection vs. non-diabetic patients
    • Restrictive lung disease from presence of ascites and pleural effusions
    • Obstructive lung disease from underlying pathophysiology e.g. smoking
    • Renal failure
    • Cardiovascular disease, in order to cope with the perioperative haemodynamic changes

Neoadjuvant chemotherapy

  • Neoadjuvant chemotherapy reduces tumour size and facilitates resection
  • Many chemotherapy drugs, however, damage hepatic parenchyma and other systems
    • Chemotherapy-associated steatohepatitis is associated with increased perioperative morbidity and mortality
    • Cardiac manifestations of chemotherapy include arrhythmia, cardiomyopathy, myocardial ischaemia and heart failure
    • Surgery should be delayed until 4 - 6 weeks post-chemotherapy to ameliorate the effects of chemotherapy on perioperative outcomes

Liver function

  • Pre-operative liver disease is a major determinant of hepatic regenerative capacity
    • Presence of liver disease is a risk factor for post-hepatectomy liver failure (PHLF)
    • Patients may have chronic liver disease; hepatocellular carcinoma often develops in patients with underlying liver cirrhosis

  • No single factor or test can reliably predictor post-operative liver dysfunction
  • Grading systems include:
    • Child-Turcotte-Pugh; class C disease is a contraindication to hepatectomy
    • MELD; score of 10 - 15 (equivalent to Child-Pugh B) is associated with increased perioperative risk

  • Volumetric assessment of liver function
    • CT and MRI may be used to estimate future liver remnant (FLR) volume
    • FLR volume accurately correlates with post-operative liver function and risk of PHLF
    • Minimum safe FLR volume:
      • 20% in those with normal liver function
      • 30 - 40% in those with severe steatohepatitis or have received hepatotoxic chemotherapy
      • 50% in those with cirrhosis

  • Estimating hepatic functional reserve
    • Dynamic hepatic function can be assessed by the degree of retention of indocyanine green dye
    • This can also be used to calculate the minimum FLR volume required to maintain essential liver function
    • If >15% of the indocyanine green dye remains in the plasma 15mins after injection, it suggests impaired hepatic clearance

Agumenting future liver remnant

  • Strategies to generate compensatory hypertrophy of the FLR can reduce the risk of PHLF
  • Options include:
    • Portal vein embolisation
    • Liver venous deprivation i.e. portal vein and hepatic vein embolisation
    • Portal vein ligation
    • Associating liver partition and portal vein ligation for staged hepatectomy (ALPSS); a two-staged hepatectomy which causes FLR hypertrophy but carries high morbidity

Acute normovolaemic haemodilution

  • This technique aims to reduce loss of red cell mass
  • The patient donates blood pre-operatively, which is replaced by fluid/albumin, causing a haemodilution
  • During the initial phases of surgery any blood lost is relatively low in haemoglobin, and this is replaced by the normal-haemoglobin autologous transfusion towards the end of the procedure
  • It does appear to reduce transfusion rate but there's no difference in the incidence of perioperative complications

Monitoring and access

  • AAGBI as standard
  • Wide-bore IV access due to high propensity for blood loss
  • Arterial line
  • Central venous access for CVP monitoring
  • Temperature monitoring and control to avoid hypothermia and coagulopathy
  • ± CO monitoring

Anaesthetic technique

  • General anaesthesia with endotracheal tube and mechanical ventilation is universal
  • In general, short-acting drugs are preferred to facilitate clear-headed wake-up post-operatively

Haemodynamic management

  • The main goal is to optimise haemodynamics in order to:
    • Minimise hepatic blood loss
    • Optimise surgical conditions
    • Maintain end-organ perfusion

    Methods for achieving a CVP <5cmH2O during phases 1-3
    Judicious fluid use
    Avoid (excessive) PEEP
    Opioid infusions e.g. remifentanil
    Trendelenburg position
    GTN infusion (venodilation)
    Phenylephrine infusion (maintain MAP)
    ± Epidural analgesia

  • The low CVP has consequences:
    • Sudden blood loss will produce severe hypovolaemia
    • IVC compression (e.g. packs, surgical retraction) will cause significantly impaired venous return
    • Higher potential for venous air embolism and subsequent hypotension
    • There may be reduced renal blood flow and consequently reduced urine output or AKI

Haemorrhage

  • The main source of bleeding during parenchymal resection (where hepatic inflow is occluded) is backflow through valveless hepatic veins
  • Control of CVP (and thus hepatic venous pressure) is crucial to reducing blood loss ± optimising surgical conditions
  • Vitamin K and TXA may also be used to mitigate risk of haemorrhage
  • Surgical methods for reducing haemorrhage;
    • Use of CUSA dissecting device; an ultrasonic energy device which preserves normal hepatic tissue
    • Haemostatic energy devices to control residual bleeding of the resected liver surgery
    • Topical haemostatic agents i.e. fibrin sealants
    • Surgical vascular occlusion (see next section)

Surgical vascular occlusion techniques

  • These techniques aim to reduce blood loss intra-operatively

  • Pringle's manoeuvre is occlusion of the hepatic artery and portal vein i.e. hepatic inflow occlusion
    • This reduces blood loss during hepatic resections, but induces warm hepatic ischaemia
      • Most surgeons will limit the duration to 15mins, with a 5min interlude before further re-clamping
      • This protects the liver by limiting total ischaemic time and inducing ischaemic preconditioning
    • Monitoring of electrolytes, glucose and coagulation status during and after Pringle's manoeuvre is required

  • Selective blood flow interruption can be achieved using hemi-hepatic or segmental occlusion of branches of the portal vein or hepatic artery
  • Total vascular exclusion provides the best conditions but poses a high risk of ischaemic injury to the future liver remnant

Emergence & extubation

  • Extubation at the end of the case is standard
  • May need NIV if significant atelectasis or respiratory failure; this reduces re-intubation rates

  • The majority of patients can be woken at the end of surgery
  • Disposition thereafter is surgery-dependent:
    • Those undergoing minimally invasive hepatectomy may go to a ward
    • Extensive or open resections may require HDU care

Analgesia

  • Effective analgesia:
    • Reduces incidence of post-operative cardiopulmonary complications
    • Encourages early return of bowel function
    • Facilitates early mobilisation

  • The choice of analgesia will depend on various factors, including whether open or minimally invasive surgical techniques are used
  • A balanced, multi-modal and opioid-sparing approach is best:
    • Paracetamol, which is safe in all but the most extensive resections
    • NSAIDs, which are effective and opioid-sparing
    • IV opioids e.g. fentanyl PCA
    • Neuraxial analgesia e.g. intrathecal morphine spinal anaesthesia, which may be quicker, safer and more reliable than thoracic epidural
    • Regional techniques e.g. continuous wound infusion catheters or trunk blocks (TAP, ESP)
  • IV lidocaine infusions cause a stastically but not clinically significant reduction in moderate-to-severe movement-evoked pain at 48hrs (BJA, 2023)

ERAS bundle

  • Oral intake should resume within a few hours after surgery
    • Those with malnourishment or prolonged fasting due to complications should be considered for (par)enteral feeding after day 5
    • Patients are hyper-catabolic post-operatively due to the high energy demands of the regenerating liver

  • Early ambulation; reduces rates of ileus, pulmonary complications and VTE
  • Multi-modal PONV prophylaxis
  • VTE prophylaxis; LMWH should commence up to 12hrs before surgery especially in major hepatectomy
  • Aim for normothermia
  • Aim for normoglycaemia


Complication Incidence Onset Notes
Infection 30% <7 days
Bile leak 4 - 17% Days Often due to iatrogenic injury or incomplete anastomosis
Coagulopathy Day 1 - 5 Thrombocytopaenia and ↑ INR due to dilutional coagulopathy + nadir of synthetic liver function
Biliary fistulae 4 - 27% Days - weeks
Post-hepatectomy liver failure 8 - 12% Day 5 onwards Manifests as ↑ INR + hyperbilirubinemia on or after day 5
Post-hepatectomy haemorrhage <3% Immediate Typically from incomplete haemostasis and residual liver edge bleeding
Post-operative anaemia Delayed Hb drop >30g/L
Hypophosphataemia Due to consumption by regenerating hepatocytes
Hyperlactataemia Hours Expected due to hepatic distress, usually self-resolves

Risk factors for post-hepatectomy liver failure

Patient factors Surgical factors Disease factors
DM/metabolic syndrome EBL >1.2L Cirrhosis
Malnutrition or obesity Need for intra-operative transfusion Steatohepatitis
Cholangitis FLR <50% volume Steatosis
Age >65yrs Operation time >4hrs Hyperbilirubinemia
Other post-operative complications Chemotherapy-associated liver injury