Does age affect liver function and the hepatic acute phase response after major abdominal surgery?

OBJECTIVE: The liver plays a key role in the inflammatory response during major surgery or infection. The influence of age on liver function and hepatic acute phase protein (APP) synthesis should be serially studied in elderly patients undergoing major abdominal surgery. DESIGN AND
SETTING: Prospective and descriptive study over 3 days. Clinical investigation in the operating room and surgical intensive care unit (ICU) of a tertiary care hospital. PATIENTS AND
INTERVENTIONS: 42 consecutive patients were grouped according to age: less than 60 years ("adult") or over 65 years ("elderly") and prospectively studied. All patients received standardized general anesthesia and were treated afterwards according to the standard protocols of our ICU. Intensivists caring for the patients were not involved in the study and were blinded to data analysis. MEASUREMENTS AND
RESULTS: Concentrations of interleukin (IL)-6, serum amyloid A (SAA), C-reactive protein (CRP), alpha1-antitrypsin (alpha1-AT), and haptoglobin were measured to assess the APP response. Liver function was evaluated by the monoethylglycinexylidide (MEGX) test and by measuring alpha-glutathione S-transferase (alpha-GST). All measurements were performed at induction of anesthesia (T0), at the end of surgery (T1), and 2 h (T2), 24 h (T3), and 48 h (T4) postoperatively. There was no difference in the incidence of postoperative septic complications between the two groups. Baseline values of IL-6 and the four APPs were normal in all patients and did not differ between the groups. IL-6 levels increased significantly in all patients at T1 and T2, with a significantly higher increase in the older patients (elderly: from 7.4+/-3.4 pg/ml to 220.6+/-49.5 pg/ml; adult: from 6.2+/-2.5 pg/ml to 189.9+/-36.8 pg/ml). A return to baseline values was seen at T3 in both groups. Concentrations of all APPs, except for haptoglobin, started to increase at T3. Peak concentrations were significantly lower in the elderly patients (elderly: SAA 358+/-133 microg/l, CRP 5.1+/-2.3 mg/dl, alpha1-AT 160+/-96 mg/dl; adult: SAA 444+/-100 microg/l, CRP 8.5+/-3.2 mg/dl, alpha1-AT 223+/-85 mg/dl). Baseline alpha-GST and MEGX concentrations were normal in all patients. Alpha-GST concentrations increased in both groups at T1 and T2, with a significantly higher increase in the older patients (elderly: 3.7+/-1.4 microg/l to 10.2+/-2.9 microg/l; adult 4.5+/-2.1 microg/l to 8.5+/-1.7 microg/l). A return to baseline values was seen at T3 in both groups. MEGX concentrations were significantly lower and abnormal (<50 ng/ml) in the older patients at T3 and T4.
CONCLUSIONS: Our observations suggest that the postoperative hepatic acute phase response is reduced in elderly patients undergoing major abdominal surgery. The decreased release of liver-synthesized APPs was associated with an impaired hepatocyte function and a disturbance of hepatocellular integrity. Further work needs to be done to determine whether these findings might have an impact on the incidence of postoperative septic complications or prognostic significance for survival in aged patients.