Improvement of cerebral blood flow patterns in hepatorenal syndrome using sustained low-efficiency dialysis

Abstract

Editor—We report the case of a 23-yr-old male with cystic fibrosis who had end-stage cirrhosis of his liver and was referred to the intensive care unit (ICU) because of decompensated hepatic encephalopathy. In the ICU, his level of consciousness deteriorated and required tracheal intubation for hypercapnic respiratory failure. He started on haemodialysis for worsening renal failure. Over the night of day 4 and into the early hours of day 5, his clinical condition deteriorated and he suffered a generalized seizure that was associated with hypoglycaemia. He had a short asystolic cardiac arrest from which he was rapidly resuscitated. Through the night, he continued with ongoing seizures requiring benzodiazepines and propofol for suppression. A computed tomographic (CT) scan done that morning revealed diffuse cerebral oedema. That afternoon, the reversal of diastolic flow in the middle cerebral artery and an increased intracranial pressure (ICP) were identified using transcranial Doppler (TCD). Calculated direction of flow index (DFI) was <0.8 (0.77). A study has suggested that if this value is <0.8, recovery to forward flow throughout diastole was never observed and no patient recovered brain stem reflexes (Fig. 1).1Kirkham FJ Levin SD Padayachee TS Kyme MC Neville BG Gosling RG Transcranial pulsed Doppler ultrasound findings in brain stem death.J Neurol Neurosurg Psychiatry. 1987; 50: 1504-1513Crossref PubMed Scopus (50) Google Scholar The possibility of an external ventricular drain was explored but due to diffuse cerebral oedema, coagulopathy, and collapsed ventricles, this was not appropriate. To manage this acute crisis, the patient was put on sustained low-efficiency dialysis (SLED) with a high effective osmolality. The investigations done before the SLED included: urea, 19.9; Cr, 288; and Na, 141. Dialysis was started at dialysate flow 550 ml min−1, blood pump speed 250 ml min−1, duration 7 h, and fluid balance=0. After dialysis, a repeat TCD study revealed a normal DFI. To our knowledge, no previous cases have been reported to date where the DFI was <0.8 and could be reversed to normal by any therapeutic interventions (Fig. 2). The next morning, TCD again showed the reversal of flow and a CT scan showed massive cerebral oedema. In consultation with the team and with the family, a decision was made to switch his goals of care to palliation and the patient died later that day. The measurement of deteriorating cerebral perfusion pressure (CPP) non-invasively is possible with TCD.2Feri M Ralli L Felici M Vanni D Capria V Transcranial Doppler and brain death diagnosis.Crit Care Med. 1994; 22: 1120-1126Crossref PubMed Scopus (59) Google Scholar As CPP approaches zero, blood vessels collapse during diastole, followed by absent or reversed diastolic flow.3Van der Naalt J Baker AJ Influence of the intra-aortic balloon pump on the transcranial Doppler flow pattern in a brain-dead patient.Stroke. 1996; 27: 140-142Crossref PubMed Scopus (12) Google Scholar A DFI was defined as DFI=1−R/F, where R is the velocity of the diastolic reverse flow and F the velocity of the systolic forward flow.4Qian SY Fan XM Yin HH Transcranial Doppler assessment of brain death in children.Singapore Med J. 1998; 39: 247-250PubMed Google Scholar A DFI<1 indicates reverse flow. Intracranial hypertension has been reported in patients with fulminant hepatic failure. With a shorter time interval between the start of symptoms and the onset of encephalopathy, there is a greater risk of cerebral oedema.5Richardson D Bellamy M Intracranial hypertension in acute liver failure.Nephrol Dial Transplant. 2002; 17: 23-27Crossref PubMed Scopus (18) Google Scholar Intermittent haemodialysis may result in an increase in ICP and has been reported to cause dialysis disequilibrium syndrome (DDS) with induced cerebral oedema that resulted in irreversible brain injury and death.6Bagshaw SM Peets AD Hameed M Boiteau PJE Laupland KB Doig CJ Dialysis disequilibrium syndrome: brain death following hemodialysis for metabolic acidosis and acute renal failure—a case report. BMC Nephrol. 2004; 5: 9Google Scholar The use of SLED gives a more gradual and stable clearance of urea. DDS has not been reported with the use of SLED.7Arieff AI Dialysis disequilibrium syndrome: current concepts on pathogenesis and prevention.Kidney Int. 1994; 45: 629-635Abstract Full Text PDF PubMed Scopus (153) Google Scholar In our patient with fulminant liver failure and signs of raised ICP, the use of SLED showed a marked improvement in cerebral perfusion and reduction of ICP. To our knowledge, this is the first reported case where any therapeutic manoeuvre managed to reverse the DFI back to normal, indicating that SLED may have a role in reducing ICP and promoting cerebral perfusion, especially in patients with severe liver dysfunction. None declared.