Doppler Ultrasound Parameters in Children After Liver Transplantation

• Author / Creator

  Ruiz,Martha

• Background: Liver transplantation is the only definite cure for patients with end-stage liver diseases. Patients that receive a liver transplant are routinely followed with periodic Doppler ultrasound because it is safe, widely available and effective to diagnose and predict some complications. While the meaning of certain Doppler ultrasound findings is clear, the diagnostic value of other routinely obtained parameters, such as the velocity of the flow, resistive index and spectrum pattern is less well understood, especially in children.
  In our research project, we aim to investigate the accuracy of Doppler ultrasound parameters in pediatric liver recipients to diagnose and predict graft-related complications, in addition to determine the prognostic value of the Doppler ultrasound assessment performed immediately after liver transplantation.

  Methods: We performed a systematic review to obtain potential normal values and thresholds of Doppler ultrasound parameters after pediatric liver transplantation. We searched for the published literature in multiple online databases and sources of gray literature. We determined the eligibility criteria a priori and performed a two-phase screening process independently by two reviewers. We extracted the data from the included studies, critically appraised their quality using the Newcastle Ottawa scale, and performed a meta-analysis of the available quantitative data.
  After this, we carried out a retrospective cohort study to analyze the potential prognostic value of the immediate Doppler ultrasound assessment to predict development of complications that require invasive management. We included all pediatric patients at a single institution (Stollery Children’s Hospital) that received a primary liver transplant between 2000 and 2019 and had a Doppler ultrasound assessment within 12 hours after the surgery. We extracted the clinical data from a local database and the Doppler ultrasound parameters from images from PACS. Descriptive statistics are presented in absolute values, percentages, median and interquartile range (IQR). Associations between predictors and outcomes were determined using univariate and multivariable logistic regression and expressed as odds ratio (OR) or adjusted odds ratio (aOR) with 95% confidence intervals (95%CI). Receiver operator characteristic curve analysis was used to find optimal thresholds for predictors.

  Results: Our final selection for our systematic review included 41 studies. All studies were observational, mainly with moderate quality, 12 of them had enough data to preformed a meta-analysis which showed the following findings: The hepatic artery resistive index (RI) was 0.15 lower in complicated grafts compared with uncomplicated (n=540, 95%CI: -0.19 to -0.11, p<.001). Findings associated with complications included a RI <0.6 (n=797, sensitivity=83%, specificity=87%, p<.001) for hepatic artery thrombosis, and a hepatic venous monophasic pattern (sensitivity=80%, specificity=78%, n=342, p<.001) for any graft complication.
  In our cohort study, our sample included 79 liver recipients with a median age of 1.3 years (0.7 – 7.2), 25 (44%) were females and 45 (57%) had a living donor. The median time between LT and DUS was 1.8 hrs (1.1 – 3.9); 61 (77%) within 4 hrs.
  Twenty-eight (35%) patients required invasive management, 51 (65%) had no or mild complications treated conservatively. The median time to detection was 11.5 days (IQR 4 - 49). The most common complications that required an intervention were hepatic artery stenosis (9, 17%), portal vein thrombosis (8, 15%), and biliary leak (8, 15%). The median follow-up was 3.16 years (IQR 1.5 – 7.0).
  Univariate analysis showed that the portal vein velocity (PVV) measured distally to the anastomosis, was significantly lower in patients that required invasive management [43 cm/s (20 - 59 cm/s) vs 60 cm/s (40 – 94 cm/s), p=0.008]. The optimal cut-off value was <60 cm/s (sensitivity=81%, specificity=54%, AUC=0.69, 95%CI: 0.57 - 0.82). No other clinical or Doppler ultrasound parameter showed prognostic value.
  Multivariate regression analysis showed a 6.4 times increase in the odds of requiring invasive management with a PVV<60 cm/s, compared with PVV≥60 cm/s, after adjusting for age, sex, diagnosis, dialysis pre-transplant, operation time and hepatic artery peak systolic velocity (PSV) (aOR=6.38, 95%CI: 1.7 - 23.7, p=0.006).

  Conclusion: A low hepatic artery RI, and a monophasic hepatic vein pattern showed statistically significant differences associated with graft complications.
  Assessment of the PVV distal to the anastomosis within the first 12 hours after the surgery provides predictive value to identify patients at high-risk for developing graft-related complications that will require invasive management.

• Subjects / Keywords

  • pediatric
  • review
  • children
  • diagnostic
  • systematic
  • liver
  • hepatic
  • Doppler
  • ultrasound
  • transplant

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-y7yz-0j91

• License

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