Feasible, safety and utility of Endoscopic ultrasound-guided PPG measurement (EUS-PPGM) in patients undergoing liver resection and major intra-abdominal surgeries.

Portal hypertension is a consequence of cirrhosis of the liver. The portal pressure gradient (PPG) is defined as the difference in pressure between the portal vein and the inferior vena cava. Clinically significant portal hypertension occurs with a PPG of 10 mmHg or above. Portal hypertension is the main driver for the majority complications of cirrhosis. Clinically significant portal hypertension is associated with an increased risk of varices, overt clinical decompensation (manifest as ascites, hepatic encephalopathy and/or variceal haemorrhage), postsurgical decompensation, need for liver transplantation and death, among many other complications. Therefore, establishing the presence and severity of portal hypertension in a patient with cirrhosis is important for prognostication, risk stratification and to guide appropriate treatment. The current gold standard for determining the portal pressure gradient indirectly via the transjugular approach and subsequent determination of the hepatic venous pressure gradient (HVPG). EUS-PPGM technique EUS-guided Portal Pressure Gradient Measurement (EUS-PPGM) approach is a newer technique, less invasive procedure to measure the portal pressure gradient directly. It is done under General anesthesia and the procedure will take around 30 mins. Each patient will undergo the procedure once prior to their surgery. The apparatus for EUS-PPGM will comprise of a linear echoendoscope, a 25G FNA needle, and a compact manometer with non-compressible tubing (Cook Medical, Bloomington, IN). The tubing will be connected by a luer lock to the distal port of the manometer, while the heparinized saline will be connected to the proximal port. The end of the tubing is connected through a luer lock to the inlet of the 25G needle. This device has been approved by the respective governing body in New Zealand for clinical use. First, a forward viewing endoscope will be inserted to document any endoscopic evidence of varices (including size and presence of red wale marks) as well as portal hypertensive gastropathy. Prior to echoendoscope insertion, the manometer will be zeroed at the midaxillary line of the patient. The hepatic vein (HV) measurement will be conducted first. Doppler flow will be used to confirm the typical multiphasic waveform of hepatic venous flow. Using the 25G FNA needle, a transgastric transhepatic approach is used to puncture the HV. Approximately 1 mL of heparinized saline will be used to flush the needle which is visible on EUS to confirm good position within the vessel. After the initial rise in pressure reading as a result of flushing, the manometer reading will equilibrate at a steady pressure, which will then be measured three times. The mean of these three pressures is then considered the HV pressure. The FNA needle is then withdrawn from the vein into the liver parenchyma, and then back into the needle sheath. The needle tract within the liver parenchyma will be observed with Doppler flow on to ensure there is no flow within the needle tract. Then the manometer will be disconnected. A separate manometer that is routinely to measure central venous pressure will be attached to the FNA needle and connect to the cardiac monitor with venous pressure waveform and numerical value display function. The manometer will be zeroed at the midaxillary line of the patient by pressing the central venous pressure ‘zero’ button on the cardiac monitor to calibrate the equipment. The CVL consists of a transducer board, fluid lines and a three-way tap. It will be necessary to administer IV fluid using a pressure bag to prime the line of the transducer with fluid to ensure it contains no air and is patent. Three pressure measurements will be taken and the mean of these three pressures is then considered the HV pressure. The FNA needle is then withdrawn from the vein into the liver parenchyma, and then back into the needle sheath. The needle tract within the liver parenchyma will be observed with Doppler flow on to ensure there is no flow within the needle tract. The portal vein (PV) measurement will be conducted next. The umbilical portion of the left portal vein will be targeted, and Doppler flow will then be used to confirm the typical venous hum of portal venous flow. Using the 25G FNA needle, a transgastric transhepatic approach is used to puncture the PV. The procedure that follows is the same as what would have been performed for the HV. Three readings will be taken, the mean of which is considered the PV pressure. Then three measurements will be repeated with a different manometer which connects to the CVL and cardiac monitor display as the same as what would have been performed for the HV. The mean of these three readings will be recorded. The patient is recovered in a similar manner to a routine diagnostic EUS with FNA, and postprocedural antibiotics are usually given for 3-5 days post procedure. The EUS-PPGM will be performed by experienced Endoscopist who had performed successfully in approximately 10 patients by very experienced Endoscopists in our Endoscopy unit in Waikato Hospital and this technique has been validated worldwide. Given the safety of EUS and its availability in current clinical practice, the use of EUS-PPGM as a routine pre-operative assessment is much more feasible than the transjugular approach. It also provides an additional objective measurement in pre-surgical selection. This study, therefore, aims to assess the feasibility, safety and utility of Endoscopic ultrasound-guided PPG measurement (EUS-PPGM) in patients undergoing liver resection and major intra-abdominal surgeries. This will be an open labelled, non-randomised, pilot prospective study to evaluate the role of EUS approach in assessing the portal pressure gradient in comparison to the transjugular approach in patients with cancer in the liver who are recommended to undergo abdominal surgery, liver resection or liver transplantation. The patients who are adults Maori and non-Maori will be recruited from the Upper Gastrointestinal multidisciplinary team meetings conducted at the Waikato Hospital, Hamilton. The patients will then be reviewed in the General Surgical outpatient clinic to discuss the potential surgical treatment options. In addition, the study will be introduced to the patients and their whanau, patient information sheet and consent form of the study will be given. Investigators will also contact the potential participants via phone or face-face clinic to check if they have any questions or concerns regarding the study. On the days of the endoscopic and radiologic procedures, the endoscopist and radiologist will also meet the patients to explain the procedure again and answer any questions or concerns.