Cirrhotic Patients in ICU with Gastro-Intestinal Bleeding Managed According to Recent Guidelines Display Altered Brain Hemoglobin Oxygen's Saturation Assessed by near Infrared Spectroscopy

Abstract

Background and aims: Near Infrared Spectroscopy (NIRS) is a non-invasive optical technique allowing a continuous measurement of brain's hemoglobin saturation in oxygen (rSO2). It is considered as a surrogate marker of cerebral insult, and recognized as a useful tool in cardiovascular surgery and neuromonitoring. A rSO2 < 50% is associated with increased neurological impairment and post-operative mortality. In cirrhotic patients with gastrointestinal bleeding (GIB), hemoglobin (Hb) threshold for transfusion has been recently lowered to 7 g/dL. Some patients develop hepatic encephalopathy (HE) after GIB. In subarachnoid hemorrhage, a threshold of 7 g/dL of Hb could worsen neurological outcome. Objective: The aim of this study was to assess brain oxygenation using NIRS in cirrhotic patients with acute GIB admitted to ICU and managed according to recent guidelines, and to determine if brain injury was associated with Hb levels. Methods: Cirrhotic patients admitted in ICU for acute GIB were prospectively included. Bilateral continuous recording of rSO2 was started upon admission using a NIRS monitor (INVOS 5100c Cerebral Oxymeter (Covidien©) with two sensors placed on the patient's forehead. Minimal rSO2 (mini rSO2), average rSO2 (avr rSO2) and AUC of rSO2 50% (AUC50% rSO2), an integrated parameter depending on the depth/duration of desaturation under 50%, were extracted. Results: 61 patients were included (age: 60 ± 10 years; 69%men). Etiology of cirrhosis was alcoholic 52%/viral 30%/NASH 15%/other 3%; Child Pugh A 17%/B 28%/C 55% and MELD score 18 ± 7. Initial Hb was 8.3 ± 1.9 g/dL and nadir within 24 first hours was 8.0 ± 1.8 g/dL. 33 patients (54%) had a nadir of Hb below 8 g/dL within the 24 first hours, and 49 (80%) patients were transfused. Mini rSO2 was 36% ± 14 right/37% ± 13 left, avr rSO2 50% ± 11 right/50% ± 10 left and AUC50% rSO2 2006 ± 2760 right/1680 ± 2618 left. 50 patients (86%) had mini rSO2 < 50%. Mini rSO2 was significantly lower in patients having a nadir of Hb below 8 g/dL (P = 0.01). Mini rSO2, avr rSO2 and AUC50% rSO2 were independently correlated to initial Hb (P < 0.001 for all), nadir of Hb within the 24 first hours (P < 0.01 for all), but only mini rSO2 was correlated to MELD score (P < 0.05). Conclusion: 86% of cirrhotic patients admitted to ICU for acute GIB and managed according to recent guidelines displayed mini rSO2 below 50% within 24 hours after admission. Low Hb levels within the 24 first hours were associated with brain desaturation. Further studies are mandatory to assess the influence of Hb thresholds on the development of HE. The authors have none to declare.