Potential conflict of interest: Nothing to report.
These authors contributed equally to the work.
Hypoxic hepatitis (HH) is the most frequent cause of acute liver injury in critically ill patients. No clinical data exist about new onset of jaundice in patients with HH. This study aimed to evaluate the incidence and clinical effect of jaundice in critically ill patients with HH. Two hundred and six consecutive patients with HH were screened for the development of jaundice during the course of HH. Individuals with preexisting jaundice or liver cirrhosis at the time of admission (n = 31) were excluded from analysis. Jaundice was diagnosed in patients with plasma total bilirubin levels >3 mg/dL. One-year-survival, infections, and cardiopulmonary, gastrointestinal (GI), renal, and hepatic complications were prospectively documented. New onset of jaundice occurred in 63 of 175 patients with HH (36%). In patients who survived the acute event of HH, median duration of jaundice was 6 days (interquartile range, 3-8). Patients who developed jaundice (group 1) needed vasopressor treatment (P < 0.05), renal replacement therapy (P < 0.05), and mechanical ventilation (P < 0.05) more often and had a higher maximal administered dose of norepinephrine (P < 0.05), compared to patients without jaundice (group 2). One-year survival rate was significantly lower in group 1, compared to group 2 (8% versus 25%, respectively; P < 0.05). Occurrence of jaundice was associated with an increased frequency of complications during follow-up (54% in group 1 versus 35% in group 2; P < 0.05). In particular, infections as well as renal and GI complications occurred more frequently in group 1 during follow-up. Conclusion: Jaundice is a common finding during the course of HH. It leads to an increased rate of complications and worse outcome in patients with HH. (HEPATOLOGY 2012)
Hypoxic hepatitis (HH) is characterized by an acute marked increase in aminotransferase levels after inadequate oxygen uptake by hepatocytes and centrilobular liver cell necrosis.1 HH predominantly results from low cardiac output and septic shock2, 3; however, other triggers, such as pulmonary diseases, have been described.4-8 More than one factor contributing to HH can be found in most patients.9, 10
Because HH is recognized as a “cytolytic” syndrome with massively elevated aminotransferase levels, jaundice (defined as bilirubin higher than 3 mg/dL) has generally been considered infrequent in this population.3, 8 However, experimental data suggest that hypoxic liver injury might lead, on the one hand, to impairment of bilirubin uptake, intracellular processing, and canalicular secretion and, on the other hand, to alterations in bile secretion and decreased bile flow.11-14 Furthermore, several studies reported that severe shock states and sepsis were reported to be major risk factors of jaundice in more heterogeneous patient populations.15-17
Taken together, the frequency of high plasma bilirubin levels after onset of hypoxic liver injury may have been underestimated, and, as a consequence, the potential clinical effect of this elevation has been neglected so far.
To date, no clinical data exist about new onset of jaundice in patients with HH, the most frequent cause of acute liver injury in critically ill patients. Accordingly, we studied frequency, risk factors, and clinical effect in regard to complications and outcome of new onset of jaundice in a large cohort of critically ill patients with HH.
Two hundred and six consecutive patients with HH were screened for the development of jaundice during the course of HH at three medical intensive care units (ICUs) of the Medical University of Vienna (Vienna, Austria).
HH was defined according to the following criteria2: (1) clinical setting of cardiac, circulatory, or respiratory failure; (2) dramatic, but transient, increase in serum aminotransferase activity reaching at least 20-fold the upper limit of normal; and (3) exclusion of other putative causes of liver cell necrosis, such as viral or drug-induced hepatitis. Liver biopsy was not required for the diagnosis of HH, in agreement with other studies showing that a histological confirmation is unwarranted,2, 18, 19 and even inadvisable, when the three criteria listed above are met. Prolonged duration of HH was defined as an increase of aminotransferases levels >24 hours. A flow chart of the study patients is shown in Fig. 1. All data were documented prospectively on a daily basis.
The aims of the current study were to investigate the prognostic effect of jaundice and to identify the associated risk factors in patients with HH. Individuals with preexisting jaundice at the time of admission were excluded from analysis (Fig. 1). Additionally, patients with liver cirrhosis were excluded from the study, as acute-on-chronic liver failure represents a distinct and separate entity.20, 21 Liver cirrhosis was diagnosed on a clinical basis or by a combination of characteristic clinical, laboratory, and radiological findings. One-year survival was assessed by contacting the patient or the attending physician and by examining the Austrian national death registry. The study was approved by the local ethics committee of the Medical University of Vienna.
Jaundice was diagnosed in patients with new onset of plasma total bilirubin levels >3 mg/dL during the stay in the ICU, as previously defined.22, 23 To determine the median duration of jaundice in patients with HH, only patients who survived the acute event of HH (>48 hours) were analyzed.
Cardiogenic shock was diagnosed in patients with (1) signs of reduced cardiac output (acute myocardial infarction [MI], low mixed or central venous oxygen saturation, or direct measurement of cardiac output by any method), (2) systolic blood pressure (BP) less than 90 mmHg without use of inotropes or vasopressors or the necessity for vasopressors, (3) presence or clinical, echocardiographic, or radiologic signs of pulmonary congestion, (4) absence of hypovolemia, and (5) end organ malperfusion, such as oliguria, lactate, cyanosis, cold extremities, or changes in mental status.24 Diagnosis of septic shock was based on well-established criteria,25 that is, documented infection or positive blood culture; at least two symptoms of a systemic inflammatory response syndrome, such as fever (temperature >38°C) or hypothermia (temperature <36°C), tachycardia (heart rate >90/min), tachypnea (respiratory rate >20/min), or hyperventilation (PaCO2 <32 mmHg), and abnormal white blood cell counts (>12,000 or <4,000/mm3 or >10% immature forms), evidence of organ dysfunction or hypoperfusion abnormality, sepsis-induced hypotension persisting, despite adequate fluid resuscitation, or use of vasopressor support. Hemodynamic parameters were recorded at admission; the maximum vasopressor dose being administred during ICU stay was documented. Anticoagulated patients receiving coumarines (n = 12) were not accounted for any analysis dealing with the international normalized ratio (INR) parameter.
New onset of complications after HH was documented prospectively during the hospital stay of the patient. Complications were classified into infections, cardiopulmonary, gastrointestinal (GI), hepatic, renal, and neurological complications. In detail, infectious complications during follow-up were defined as pneumonia, bloodstream infections, urinary tract infections (UTIs), and infections of the soft tissue according to widely accepted criteria.26-28 Cardiopulmonary complications during follow-up were defined as cardiopulmonary resuscitation, acute MI, and others. GI complications were defined as bleeding complications,29 mesenteric ischemia,30, 31 and others. Hepatic complications were classified as reoccurrence of HH and development of secondary sclerosing cholangitis (SSC). Renal complications were defined as initiation of renal replacement therapy (RRT) after occurrence of HH. Neurological complications were defined as cerebral infarction, intracranial bleeding, cerebral herniation, and others.
Statistical analysis was performed using SPSS 17 (SPSS, Inc., Chicago, IL). Data are presented as median (interquartile range; IQR) or as number of cases and percentage, as appropriate. For univariate analysis, Mann-Whitney's U test or chi-squared test were used, as appropriate. A multivariable logistic regression model was used to identify independent predictors of the development of jaundice and to evaluate the effect of jaundice on new onset of complications during follow-up. Potential predictors were defined a priori or based on associations in the univariate analysis. Factors with colinearity were left out of the analysis. Two-sided statistical significance was required at the 95% level (P < 0.05).
This prospective series included 206 patients with HH, collected during a 48-month period from 2006 to 2009. Patients with preexisting jaundice (n = 19), liver cirrhosis, or both (n = 12) were excluded from the analysis. Of the remaining 175 patients who met the inclusion criteria, 63 patients (36%) developed jaundice (group 1), which occurred after a median of 2 days (IQR, 2-4) after the onset of HH. One hundred and twelve patients did not develop jaundice (group 2). Main clinical and biological characteristics are reported in Tables 1 and 2. In patients who survived the acute event of HH, median duration of jaundice was 6 days (IQR, 3-8). Peak bilirubin levels (5.1 mg/dL; IQR, 3.6-8.4) were observed on median day 4 (IQR, 2-6) in group 1. Plasma levels of bilirubin returned to normal in 27 (43%) patients, whereas 36 (57%) subjects died with elevated levels of bilirubin.
Table 1. Patient Characteristics
Jaundice (Group 1)
No Jaundice (Group 2)
Abbreviations: bpm, beats per minute; TPN, total PN.
Patients in group 1 had significantly higher severity of illness, as illustrated by higher sequential organ failure assessment (SOFA) and simplified acute physiology score II (SAPS II), on admission, higher rates of mechanical ventilation, RRT, vasopressor requirement, and dose and prolonged duration of HH (Table 1). Furthermore, peak liver function parameters were significantly higher in patients of group 1 (Table 2; Fig. 2). Jaundice was significantly linked to HH that followed septic shock (P = 0.018%) and was inversely associated with cardiogenic shock (P = 0.043). Factors associated with the development of jaundice were entered into multivariate regression analysis, which revealed that higher SAPS II score at admission and peak INR levels were independent predictors of new onset of jaundice after HH (Table 3).
Table 3. Risk Factors for the Development of Jaundice
ICU mortality was 64% (n = 40) and 53% (n = 59) (P = 0.17) for groups 1 and 2, respectively. One-year survival rate (Fig. 3) was significantly lower in group 1, compared to group 2 (8% versus 25%, respectively). Cardiogenic shock was the most common cause of death, followed by septic shock and sudden cardiac arrest. Death subsequent to septic shock was significantly higher in group 1 (21 [36%] versus 17 [20%]; P = 0.035).
Complications During Follow-up.
Complications during follow-up are listed in Table 4. Thirty-four (54%) patients in group 1 and 39 (35%) in group 2 developed at least one complication (P = 0.014). We observed a second episode of HH in 1 patient after aminotransferase levels had fully regressed that occurred on day 5 after the initial event. Five patients in group 1 and 3 in group 2 developed an ischemic event of the intestine (median onset at day 16.5; IQR, 3.5-27.5). Mesenteric ischemia led to the development of acute peritonitis in 6 patients, requiring urgent partial colectomy. One patient died within hours without option for surgical intervention, and in 1, computed tomography findings of mesenteric ischemia recovered within 13 days. Overall infections (P = 0.001), as well as pneumonia (P = 0.002), occurred more frequently in group 1 and were diagnosed after a median of 8 days (IQR, 4-24) after onset of HH without a significant difference of onset between the two groups (P = 0.67). The number of bloodstream infections was similar in the two groups. GI (P = 0.022) and renal complications (P = 0.002) were observed more frequently in group 1 (Table 4). In the present study cohort, 1 patient developed the typical cholangiographic signs of SSC.32
Our results demonstrate that jaundice occurs frequently after onset of HH: Almost 4 of 10 patients with HH developed hyperbilirubinemia >3 mg/dL during the course of their disease. This incidence is considerably higher than in more heterogeneous patient populations reported on by other investigators.16, 23, 33, 34 The notably high incidence of jaundice in patients after HH may particularly reflect the higher severity of the underlying diseases that consecutively increases the number of potential risk factors of jaundice. This assumption is strengthened by the fact that patients in group1 had higher SAPS II and SOFA scores on admission, despite the absence of jaundice at study inclusion. Of note, total serum bilirubin levels (BILI) are part of many applied prognostic organ dysfunction scoring systems at the ICU, such as SAPS II and SOFA scores.35-37 Multivariate regression analysis identified SAPS II score on admission and peak INR as independent risk factors for the occurrence of jaundice in patients with hypoxic liver injury. Severity of illness and degree of hepatic impairment were already identified as independent predictors of mortality in a previous study of patients with HH.9
Patients with high severity of illness exhibit multiple risk factors for jaundice, such as new onset of infections and the necessity of vasopressor treatment, mechanical ventilation, RRT, and parenteral nutrition (PN).
Sepsis was recently shown to be an independent predictor of mortality in patients with HH,9 and, in turn, inflammation seems to play a key role in the development of jaundice and cholestasis.38, 39 Significant alterations in both canalicular and basolateral transport systems have been described in the isolated perfused rat liver, rat hepatocytes, and in purified membranes obtained from endotoxin-treated rodents.40-45 Recently, Mesotten et al. reported on the prevalence of cholestasis (defined as bilirubin levels >3 mg/dL) of 20% in a medical long-stay ICU population.23 In a follow-up study, the same group reported on significantly elevated bile acid levels and altered receptor expression.46 Indeed, septic shock as a cause of HH was a significant risk factor of hyperbilirubinemia in our population, whereas the incidence of cardiogenic shock indicated lower probability to develop jaundice. Patients in group 1 seemed to be prone to developing infections, such as pneumonia, and died from septic shock more frequently. Therefore, special attention should be paid to avoid a septic state in patients with HH.
Vasopressor therapy is another potential risk factor for the development of jaundice. It has been recently shown that the necessity of catecholamine therapy indicates poor outcome in patients with HH.9, 47 In the present study, both vasopressor administration and also higher doses of administered norepinephrine were significantly associated with new onset of jaundice. This is in line with experimental findings when portal venous administration of vasopressors induced cholestasis in the isolated perfused rat liver.14 Moreover, catecholamine therapy may stimulate an inflammatory response in human hepatocytes in vitro, which, in turn, may lead to dysfunction of cholangiocytes.48 Additionally, Yang et al. showed that intraportal infusion of norepinephrine in healthy animals is capable of producing hepatocellular dysfunction, as assessed by in vivo indocyanin green clearance.49 The same group proposed that intraportal administration of norepinephrine, as well as gut-derived norepinephrine during experimental sepsis, up-regulates tumor necrosis factor alpha (TNF-α) gene expression in Kupffer cells and TNF-α plasma levels.49, 50
We found a significant association between mechanical ventilation and the development of jaundice. This might be explained by alterations of hepatic perfusion during mechanical ventilation. Portal venous and hepatic arterial blood flows as well as hepatic venous oxygen saturation (an indicator of the adequacy of hepatic oxygen supply) are reduced in animals treated with positive endexspiratory pressure (PEEP) because of PEEP-induced decreases in cardiac output.51-53 Accordingly, an increase of PEEP levels induced a significant decrease in hepatic blood flow in critically ill patients.54 Our results indicate that mechanically ventilated patients are more prone to develop jaundice. However, the degree of the applied PEEP level did not influence its occurrence significantly.
Enteral nutrition (EN) seems to carry out a positive effect on the biliary function of the critically ill.55 Impaired hepatic blood flow resulting from PEEP ventilation was increased by enteral feeding in an experimental setting.56 In contrast, different patterns of liver dysfunction are well-known complications in critically ill patients who receive PN.57, 58 Fasting coupled with PN has been shown to reduce the secretion of a number of GI hormones, including gastrin, motilin, pancreatic polypeptide, insulinotropic polypeptide, and glucagon.59 This reduction in secretion may reduce intestinal motility, promoting bacterial overgrowth, and may predispose to biliary stasis.59 Although we found no significant effect of PN on the occurrence of jaundice in our cohort, we observed a trend toward a protective effect of EN, in line with recent work by Casaer et al.60
New onset of RRT was observed in significantly more patients with jaundice after the occurrence of HH. Apart from the higher severity of disease, patients in group 1 may be more prone to new-onset renal dysfunction resulting from jaundice per se. Hemodynamic alterations after infection, endotoxinemia, and hypovolemia are reported to be the main mediators of the multifactorial etiology of renal dysfunction in jaundice.61, 62 Recently, a histopathological study reported on acute tubular necrosis and venous dilatation in a series of patients with acute obstructive jaundice, despite strict volume control.63 Taking into account the increased number of infections in patients with jaundice and HH, strict infection control and adequate fluid balance seem to be important, especially in this population.
The increased rate of complications in patients with HH and jaundice may not be solely the consequence of the more-advanced severity of illness. New onset of jaundice per se seems to be an independent risk factor for complications and worse outcome in the course of HH. The antioxidative properties of bilirubin may forward and aggravate bacterial infections and contribute to impaired bactericidal properties of neutrophils.64 Features of an unbalanced immune response in acute hepatic impairment may lead to or aggravate multiorgan failure.65, 66 Furthermore, hepatic injury may induce distinctive functional, morphological, and oxidative changes of intestinal mucosa in parallel to hepatic damage and leads to increased vulnerability to injury, bacterial overgrowth, and translocation and parallels hepatic oxidative damage.65, 67 Finally, as mentioned above, jaundice may aggravate renal failure.
SSC is a rare, but deleterious, disease pattern with progression to liver cirrhosis.32 Impaired hepatic blood supply is thought to especially compromise the integrity of the biliary epithelium because of its specific vascular anatomy. The hepatic parenchyma receives a dual blood supply from the hepatic artery and the portal vein, whereas the biliary tree, and, in particular, the perihilar extrahepatic and the intrahepatic biliary tree, receives blood exclusively from the hepatic arterial branches known as the peribiliary vascular plexus.68, 69 Therefore, patients with HH are thought to be at high risk of developing ischemic cholangitis. However, only 1 patient developed SSC in the present study. Because SSC seems to be a rather rare disease,70 perhaps an even larger cohort of patients with HH is needed to draw a conclusion about the incidence of SSC in patients with HH. Our data indicate that a severe, but rather short, hit to the hepatic circulation and oxygenation rarely contributes to the occurrence of SSC. This is in accord with the literature, where most underlying conditions contributing to SSC were prolonged severe hypoxemia and inflammation, such as in acute respiratory distress syndrome or extracorporeal circulatory support devices.
In summary, new onset of jaundice is a frequent finding in critically ill patients with HH and is associated with an increased number of complications and increased 1-year mortality. Severity of illness and degree of hepatic injury during the acute phase of HH are the main triggers of jaundice. Jaundice per se is associated with adverse events, such as nosocomial infections as well as renal and GI complications. Future studies should evaluate whether preventive or therapeutic strategies are able to reduce the high rate of jaundice and its associated complications in patients with HH.