Autoregulation Assessment During Liver Transplantation
Patients with liver failure undergoing liver transplantation often have clinical or sub-clinical encephalopathy that may lead to increased intracranial pressure. The latter may lead to abnormal regulation of blood flow to the brain (cerebral autoregulation) complicating patient management during and after general anesthesia. The current methods for monitoring for elevated intracranial pressure are invasive and, thus, limited to severe encephalopathy. In this study the investigators will evaluate the potential utility of monitoring cerebral blood flow autoregulation non-invasively using near infra-red spectroscopy in patients undergoing liver transplantation.
Other: Near infrared spectroscopy monitoring
Other: Autoregulation monitoring
|Study Design:||Observational Model: Cohort
Time Perspective: Prospective
|Official Title:||Non-Invasive Assessment of Cerebral Blood Flow Autoregulation in Patients Undergoing Liver Transplantation|
|Study Start Date:||September 2011|
Patients will be grouped into Meld Score
Other: Near infrared spectroscopy monitoring
This is an observational study without interventions
Other Name: Cerebral oximetry index and hemaglobin volume indexOther: Autoregulation monitoring
There are no interventions in this observational study
Other Name: Cerebral oximetry
Hepatic encephalopathy complicating chronic liver failure in patients undergoing liver transplantation increases the risk for adverse outcomes including mortality. Even mild hepatic encephalopathy may not be recognized clinically without specific testing but can be associated with impaired functional status and reduced quality of life before liver transplantation. The changes that can be seen in chronic liver failure, (cerebral edema and increased intracranial pressure) can adversely affect cerebral blood flow autoregulation that may predispose to brain injury during the multiple hemodynamic perturbations that occur during and after liver transplantation. Currently, invasive monitoring with an intracranial "bolt" is the only method to aggressively manage patients with elevated intracranial pressure from acute liver failure and hepatic encephalopathy. The placement of an intracranial pressure catheter in patient with liver failure is associated with a risk of brain hemorrhage due the presence of a coagulopathy. Further, the risk of this type of monitoring outweighs the benefits in the patients with milder or subclinical forms of hepatic encephalopathy. In this pilot study of 20 patients undergoing liver transplantation we will evaluate the feasibility of non-invasive monitoring of CBF autoregulation and assess whether autoregulation is impaired in this group of patients. We hypothesize that cerebral blood flow autoregulation is impaired in patients undergoing liver transplantation based on severity of liver disease. In this situation, improved patient monitoring would allow clinicians to maintain arterial blood pressure above an individual's lower limit of cerebral blood flow autoregulation that might prevent devastating brain injury during and after surgery. Cerebral blood flow autoregulation can be continuously monitored by evaluating the correlation coefficient between cerebral blood flow velocity measured with transcranial Doppler and arterial blood pressure. Our group has developed a novel method of autoregulation monitoring using near infrared spectroscopy that allows continuous monitoring of autoregulation with the cerebral oximetry index and the hemoglobin volume index(, a moving linear correlation coefficient between cortical tissue oxygen saturation and hemoglobin level with arterial blood pressure, respectively. The latter approach is more practical and would allow widespread autoregulation monitoring in diverse clinical settings. A secondary hypothesis of this study is that near infrared spectroscopy-based monitoring of CBF autoregulation will provide an accurate assessment of the limits of autoregulation compared with the more clinically challenging transcranial Doppler methods .
- To assess whether patients undergoing liver transplantation have impaired cerebral blood flow autoregulation.
- To evaluate whether non-invasive monitoring of cerebral blood flow autoregulation with cerebral oximetry index and hemoglobin volume index can identify the lower limit of autoregulation within 10 mmHg compared with that measured with transcranial Doppler.
|Contact: Charles W Hogue, MD||(410) email@example.com|
|Contact: Michelle Parish, BSNfirstname.lastname@example.org|
|United States, Maryland|
|The Johns Hopkins Hospital||Not yet recruiting|
|Baltimore, Maryland, United States, 21287|
|Principal Investigator: Charles W Hogue, MD|
|Principal Investigator:||Charles W Hogue, MD||The Johns Hopkins University School of Medicine|