Clinical utility of an automated pupillometer for assessing and monitoring recipients of liver transplantation

Abstract

Pupil examination has been used as a basic measure in critically ill patients and has great importance for the prognosis and management of disease. An automated pupillometer is a computer-based infrared digital video system by which the accuracy and precision of the pupil examination are markedly improved. We conducted an observational study of pupil assessment with automated pupillometry in clinical liver transplantation settings, including pretransplant evaluations and posttransplant surveillance. Our results showed that unconscious patients (grade 4 hepatic encephalopathy) had a prolonged latency phase (left side: 283 Ϯ 80 milliseconds; right side: 295 Ϯ 96 milliseconds) and a reduced pupillary constrictive ratio (left direct response: 0.23 Ϯ 0.10; left indirect response: 0.21 Ϯ 0.07; right direct response: 0.20 Ϯ 0.08; right indirect response: 0.21 Ϯ 0.08) in comparison with normal and conscious patients. After liver transplantation, the recovery of pupillography in these patients was slower than that in conscious patients. However, the surviving recipients without major complications all had a gradual recovery of pupillary responses, which occurred on the first or second posttransplant day. We also reported 4 cases of futile LT in the absence of pretransplant pupillary responses and other pupillary abnormalities revealed by automated pupillometry in our study. In conclusion, patients with grade 4 hepatic encephalopathy had a sluggish pupil response and a delayed recovery pattern after LT. An automated pupillometer is potentially a supplementary device for pretransplant screening and posttransplant monitoring in patients undergoing LT, but further prospective studies are required. Liver Transpl 15: 1718-1727, 2009. © 2009 AASLD. Received March 16, 2009 accepted August 11, 2009. Liver transplantation (LT) is an effective treatment for patients with irreversible hepatic failure; however, mortality and morbidity are higher in critically ill recipients.1,2 Although hepatic encephalopathy (HE) is not included in the Model for End-Stage Liver Disease system of organ allocation, for patients with encephalopathy IV, there is no standard methodology for predicting whether a recipient will wake up from a deep coma after a technically successful transplant. Fulminant hepatic failure patients with an almost flat electroencephalogram have a chance of survival after LT, whereas some other patients do not recover consciousness.3 Brain edema and intracranial hypertension in acute liver failure have been emphasized for peritransplant monitor-

Automated Quantitative Pupillometry for the Prognostication of Coma After Cardiac Arrest

“…In critically ill patients, two preliminary studies found that the measurement of pupillary size with an automated pupillometer was more accurate than standard pupillary examination using a manual pen light [16,17]. Yan et al [18], in a larger cohort of liver transplant patients, found that peri-operative pupillary abnormalities measured with quantitative pupillometry were associated with neurological complications. Behrends et al [19], in a small cohort of 30 patients, found that quantitative pupillary reactivity performed during cardio-pulmonary resuscitation was associated with early survival.…”

Clinical Utility of an Automated Pupillometer in Patients with Acute Brain Lesion

“…Meeker et al 12) reported that inter-examiner disagreement regarding the pupillary reaction was 39% for manual examinations compared with 1% for automated pupillometers. Hence, studies to define the relationship between clinical manifestations and PLR determined by automated pupillometer have been conducted in various fields 1 2 5 6 7 9 15 17 18) .…”

“… 15) In emergency medicine, research revealed that the presence of PLR, determined by automated pupillometer in patients with "fixed" pupils according to manual examinations, could be associated with early survival and a favorable neurological status in the recovery period 11) . Automated pupillometers were also used to assess the prognosis of patients receiving a liver transplantation 18) . Some anesthesiologists and pharmacologists have shown that automated pupillometers could be used to quantify the PLR, which can be affected by drugs and hence can provide proper information about the responses to these drugs 6 9 17) .…”

Hepatic Encephalopathy—the Old and the New

“…11 Loss of pupillary function can signify brain herniation owing to uncal compression of ciliary fibers of cranial nerve III. However, loss of pupillary function may be caused by metabolic abnormality in late stages of HE.…”