Anaesthesia for major liver resection
The liver is a highly vascular organ with a blood flow of 1500 mL/min, the portal vein contributing 75% and the hepatic artery 25% of the total flow. The liver can be divided into eight functional segments, based on their blood supply and biliary drainage, and this forms the basis of the various types of liver resection that may be possible. Large volumes of the liver may be resected, without the subsequent development of liver failure, due to the liver’s capacity to regenerate, a process that starts as early as 24 hours post-resection.
Prior to resection taking place, a preoperative assessment must establish that a sufficient liver remnant will be left post-resection. This is done radiologically. For patients with a normal liver, a remnant of approximately 20% is required; for those with significant steatosis or hepatic dysfunction, a much larger remnant is required. Patients requiring a resection that would leave an inadequate liver remnant may undergo selective portal vein embolization 6 weeks prior to resection, to facilitate hypertrophy of the proposed remnant.
1 Outline the preoperative assessment of a patient for liver resection
2 Discuss the anaesthetic and surgical techniques to minimize complications such as blood loss
3 Appreciation of the possible post-operative complications.
2A03; 2A07
A 68-year-old man is listed for an extended right hepatectomy for metastatic disease. Eighteen months previously, he had an anterior resection for carcinoma of the colon. Follow-up imaging at 12 months revealed metastatic deposits in liver segments 4 and 8. He has recently completed a course of neoadjuvant chemotherapy. He is a lifelong smoker, with mild COPD, and takes regular inhaled beclomethasone and tiotropium. He has a moderate alcohol intake.
◆ The general cardiorespiratory reserve for major laparotomy, including the effects of chemotherapy
◆ The hepatic function
◆ The extent of resection.
◆ FBC, U&E, LFTs, coagulation screen, cross-match, ECG, CXR
◆ Pre-chemotherapy computed tomography (CT) or MRI to assess the extent of liver resection required and the size of the liver remnant
◆ Positron emission tomography (PET) scan to exclude extrahepatic disease.
◆ Major haemorrhage requiring massive transfusion
◆ Cardiovascular instability secondary to vascular isolation during resection
◆ Air embolism.
◆ General anaesthesia, with either a thoracic epidural or PCA for post-operative analgesia
◆ Large-bore venous access
◆ A rapid infusion device should be available
◆ Arterial and central venous pressure monitoring
◆ A urinary catheter
◆ Normothermia
◆ Intraoperative ABG and ROTEM® analysis may be useful
◆ Prophylactic antibiotics.
◆ Inflow vascular occlusion, including Pringle manoeuvre
◆ Maintaining a low central venous filling pressure
◆ Avoidance of acidosis, hypothermia, and hypocalcaemia.
The patient’s surgery has proceeded uneventfully, and he has been subsequently extubated and transferred to the HDU. The intraoperative blood loss was 800 mL. On admission to the HDU, routine blood analysis demonstrates Hb 98 g/L, Plt 145 × 109/L, Na+ 135 mmol/L, K+ 4.0 mmol/L, urea 7.8 mmol/L, Cr 112 micromoles/L, PT 14 s, and lactate 2.8 mmol/L. He has an epidural in situ, and initial observations are HR 65 bpm, BP 100/50 mmHg, CVP 5 mmHg, and urine output 30–40 mL/hour.
Over next few hours, the patient becomes hypotensive with a low CVP. A total of 1000 mL of Gelofusine® is administered, and an ABG sampling at this time demonstrates Hb 94 g/L, H+ 56 nmol/L, PaO2 14 kPa on 4L/min of oxygen, PaCO2 5.8 kPa, and lactate 3.9 mmol/L.
The patient fails to respond to the fluid bolus, and, over the next hour, he has a further 2000 mL of Gelofusine® and a noradrenaline requirement of 0.2 mcg/kg/min. His HR is 110 bpm, BP 85/50 mmHg, and CVP 3 mmHg. Blood tests show Hb 84 g/L, Plt 101 × 109/L, PT 19 s, lactate 7.8 mmol/L, and BM 2.8 mmol/L.
◆ Continue cardiovascular resuscitation
◆ Dextrose bolus
◆ The patient requires immediate return to theatre, as there are concerns regarding the vascular supply to the liver remnant. Ensure blood for transfusion will be available in theatre
◆ ROTEM® may help direct point-of-care management of evolving coagulopathy.
On reopening, a congested liver remnant was found, with an obstructed outflow noted. Surgical correction of this results in a dramatic reduction in fluid and noradrenaline requirement. The patient returns to ICU, intubated and ventilated, with a plan to remain so overnight. Readmission bloods are Hb 78 g/L, WCC 15 × 109/L, Plt 98 × 109/L, PT 18 s, lactate 5.6 mmol/L, and BM 6.8 mmol/L.
He remains cardiovascularly stable overnight, requiring maintenance fluid only and no blood or blood product administration. Lactate continues to fall, and the acidosis resolves, allowing the noradrenaline to be weaned in parallel. The following morning, his routine bloods show Hb 81 g/L, Plt 108 × 109/L, PT 15 s, lactate 2.9 mmol/L, BM 5.9 mmol/L, and ALT 980.
◆ Extubate
◆ Continue the epidural for further 24 hours, then remove if the platelet count and PT are within the normal range
◆ Monitor liver function: ALT may rise further but should decrease over the next few days, unless further problems
◆ Look out for any evidence of sepsis: a further liver ‘hit’ could be devastating
◆ DVT prophylaxis and peptic ulcer prophylaxis
◆ Establish enteral feeding.
Liver resection was previously associated with significant mortality, primarily due to major blood loss. Change in anaesthetic and surgical techniques has now reduced mortality to approximately 3%. Indications for hepatic resection include:
1 Metastatic colorectal carcinoma
2 Primary hepatocellular carcinoma (HCC)
3 Cholangiocarcinoma
4 Neuroendocrine tumours
5 Live donor liver transplantation.
All patients will be intubated and ventilated. Intra-arterial BP and CVP monitoring is essential in all major resections, as is wide-bore venous access. Both an epidural or opioid PCA may be used for post-operative analgesia, and each has its advantages and disadvantages.
Surgical techniques to reduce blood loss include vascular isolation techniques such as the Pringle manoeuvre which involves occlusion of the hepatic artery and portal vein. This inflow occlusion means that an intraoperative blood loss is primarily from the hepatic veins. Therefore, fluid restriction and maintenance of a low CVP are required to reduce blood loss. The cardiovascular effects of inflow occlusion include a significant increase in the SVR and a reduction in the cardiac index.
The use of laser coagulation and ultrasound aspiration during resection has also been instrumental in the reduction of intraoperative blood loss.
The development of a coagulopathy is more likely in patients who are hypothermic, hypocalcaemic, or have pre-existing cirrhosis or steatosis, or have had chemotherapy. Blood sugars should be monitored, especially if there is a prolonged period of vascular occlusion.
All patients are monitored in a critical care area following a major liver resection. Mortality rates have significantly reduced and are now in the region of 2–3%. Significant morbidity remains a concern, particularly in patients who have a small liver remnant or have pre-existing liver disease.
Early post-operative haemorrhage may require immediate return to theatre, following the correction of coagulopathy. Bile leaks are relatively common but should respond to antibiotics if they are of small volume. Larger volumes of bile leaks will require endoscopic retrograde cholangiopancreatography (ERCP) and biliary stenting. Sepsis from any cause will delay the liver regeneration; therefore, a high index of suspicion is required, and early diagnosis and treatment are essential.
Small-for-size syndrome may develop in patients who have extended resections or a poorly functioning remnant. It usually presents with evidence of sepsis and the derangement of LFTs. Management is conservative, with organ support, appropriate antibiotic therapy, and the control of sepsis. Mortality is high.
Summary
The main indications for liver resection are colorectal metastases or HCC. Therefore, significant cardiorespiratory comorbidities may co-exist.
Good communication between the surgeon and the anaesthetist is essential throughout the perioperative period. Intraoperative invasive monitoring and wide-bore venous access are essential, as haemodynamic instability and significant blood loss may occur.
Post-operative management initially requires a period of critical care, and complications, such as bleeding and sepsis, must be identified and managed urgently.
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