Postoperative hyperamylasaemia in cardiac surgery

Cystatin C in diabetics as a marker of mild renal insufficiency after CABG

PURPOSE

The purpose of this study was to evaluate the accuracy of plasma cystatin C in acute impairment in renal function; plasma cystatin C was compared to plasma creatinine in two hundred patients undergoing elective CABG surgery.

METHODS

We performed a prospective clinical study of two hundred patients undergoing coronary bypass surgery. Plasma creatinine and cystatin C were measured preoperatively and on the first and fourth days after surgery. Estimated glomerular filtration rate (GFR) was calculated using one creatinine-based and two cystatin C-based equations.

RESULTS

There were 144 non-diabetic and 56 diabetic patients. The need for furosemide was more common among diabetics (80.4% of the patients vs. 53.9%, p = 0.024). Changes in cystatin C-based GFR with both equations were significantly greater in the group of diabetics (-14.3 ± 28.0 and -11.2 ± 19.3 ml/min/1.73 m(2) vs. -4.3 ± 26.9 and -3.1 ± 20.5 ml/min/1.73 m(2), p = 0.025 and 0.016, respectively). Changes in creatinine-based GFR did not differ between the diabetics and the non-diabetics.

CONCLUSION

Cystatin C and cystatin C-based estimation of GFR may be useful and more sensitive than creatinine in detecting mild acute renal insufficiency in diabetic patients.

Detection of postoperative pancreatitis after pancreatic surgery by urine trypsinogen strip test

Background

The urine trypsinogen strip test has been used successfully in the diagnosis of pancreatitis of various aetiologies, but has not been studied in postoperative pancreatitis. The aim of this study was to evaluate this test for the diagnosis of postoperative pancreatitis after pancreatic resection.

Methods

Fifty patients undergoing pancreatic resection were included. The urine trypsinogen strip test was done daily during the first postoperative week, blood was analysed before and 4, 6 and 10 days after surgery, and amylase activity in the drainage fluid was measured on days 4 and 6. Patients underwent computed tomography (CT) before operation and on days 2 and 6 afterwards.

Results

Thirteen patients (26 per cent) developed CT-detected pancreatitis after operation. In 12 of these patients pancreatitis was detected on the second postoperative day. The urine trypsinogen test was positive in all 13 patients with postoperative pancreatitis, and was already positive on the first day after surgery in 12. The sensitivity, specificity, and positive and negative predictive values of the trypsinogen strip test in detection of postoperative pancreatitis were 100, 92, 81 and 100 per cent respectively. In receiver–operator characteristic analysis the area under the curve (AUC) was higher for the urine trypsinogen strip test (AUC 0·959) than for a serum amylase level more than two (AUC 0·731) or three times (AUC 0·654) above the upper normal range in the diagnosis of postoperative pancreatitis. Patients whose recovery was complicated by pancreatic fistula, detected by drain output measurements on day 6, more often had a positive urine trypsinogen test than patients without a fistula (11 of 12 versus five of 38; P < 0·001).

Conclusion

This study suggests that the urine trypsinogen strip test might be a valuable method for diagnosis of pancreatitis after pancreatic surgery.

Hyperamylasemia and subclinical pancreatitis after cardiac surgery

Hyperamylasemia after cardiac surgery is common but typically causes no clinical concern because it consists mainly of the salivary isoenzyme. In this study we evaluated the incidence, source, and time course of postoperative hyperamylasemia with special attention to the possibility of subclinical pancreatitis. In 88 patients prospectively tested for serum amylase and lipase concentrations, elastase 1 activity, and amylase isoenzyme characteristics, 57 (64%) showed hyperamylasemia during the early postoperative period. In most cases early hyperamylasemia was not of pancreatic origin, but two patients were diagnosed with subclinical pancreatitis. Among the last 23 patients, 5 of 10 patients with early hyperamylasemia exceeding 1000 IU/L showed late hyperamylasemia on the seventh postoperative day, when it represented mainly the pancreatic isoenzyme. Lipase concentrations and elastase 1 activities were elevated in these cases. Late hyperamylasemia following cardiac surgery may be of pancreatic origin and indicative of subclinical pancreatitis, even if early hyperamylasemia was of salivary origin.

Hyperamylasemia after cardiopulmonary bypass: pancreatic cellular injury or impaired renal excretion of amylase?

BACKGROUND

Postoperative hyperamylasemia and even acute pancreatitis are associated with coronary artery bypass grafting (CABG). The mechanism of hyperamylasemia and pancreatic acinar cell damage was studied in 20 patients undergoing CABG.

METHODS

Serial blood and urine samples at eight time points before, during, and 24 hours after the CABG were collected. Salivary and pancreatic isoamylases, the fractional clearance of isoamylases (i.e., relative to creatinine clearance), pancreatic phospholipase A2 (a specific serum marker of pancreatic acinar cell injury), and cystatin C (a sensitive marker of glomerular filtration rate) were measured.

RESULTS

Mild serum hyperamylasemia (300 to 1000 units/L) was found in 11 of 20 (55%) and severe (> 1000 units/L) in 6 of 20 (30%) patients with no signs of clinical acute pancreatitis. Hyperamylasemia occurred from 6 to 24 hours after the CABG and was mainly caused by pancreatic isoamylase. Serum pancreatic phospholipase A2 concentration remained unchanged, which excludes acinar cell damage. Although renal glomerular filtration was normal during CABG as measured by serum cystatin C and creatinine clearance, the fractional clearance of isoamylases decreased.

CONCLUSIONS

The decreased rate of excretion into urine, rather than pancreatic cellular damage, is the major source of hyperamylasemia after CABG.