Peri-operative assessment of glomerular permeability

Microalbuminuria in acute burn injury

Microalbuminuria is a known finding in inflammatory states. We hypothesized that urinary albumin/creatinine ratio (ACR) would correlate with injury severity and resuscitation demands after acute burns. This pilot study evaluated 30 adults admitted within 12 hours of injury with burns > or =10% total body surface area burn injury (TBSA). The urinary ACR was calculated for each patient at 7 to 12 hours, 19 to 24 hours, and 43 to 48 hours following burn injury. Microalbuminuria was defined as a urinary ACR > or =20 mg/g. Study patients (23 males, 7 females) had a mean age of 42.9 + 14.0 years and a median TBSA burn injury of 18.8%. Inhalation injury was present in 10 of the study patients, and all patients with inhalation injury had microalbuminuria at the time of admission. One study patient died. Median time from burn injury to resuscitation was 30 hours, and the median fluid requirement was 4.2 ml/kg/%TBSA. Microalbuminuria was not uniformly present in burn-injured patients during the first 48 hours after injury. ACR values early in the hospital course correlated with higher lactate concentrations early after burn injury. However, ACR correlated with neither injury severity nor resuscitation demands after burn injury during any studied time range. Microalbuminuria does not have apparent clinical utility in burn-injured patients, and other markers of injury severity and resuscitation demands should be sought.

Increased glomerular permeability and pulmonary dysfunction following major surgery: correlation of microalbuminuria and PaO/FiO ratio

BACKGROUND

The aim of our trial was to evaluate the ability of microalbuminuria as an indicator of outcome and to investigate its relationship with the postoperative respiratory dysfunction in the initial postoperative period in a high-risk patient group.

METHODS

In our prospective, observational study patients were consecutively recruited following elective oesophagectomy, total gastrectomy, Whipple-resection of the pancreas and liver resection due to tumour removal. Microalbuminuria (expressed as urine albumin:creatinine ratio, M:Cr) was measured before (tp), and after surgery (t0, t6, t24, t48, t72). Multiple Organ Dysfunction Scores were monitored on ICU admission than daily (t1, t2, t3). For statistical analysis, Wilcoxon's rank-sum test, Mann-Whitney's U-test, receiver operating characteristic curve analysis and Spearman's rho test were used as appropriate.

RESULTS

One hundred and forty patients (118 survivors and 22 non-survivors) were recruited. Significantly higher Multiple Organ Dysfunction Scores were observed in non-survivors throughout the study period (P < 0.001). Microalbuminuria (Cr) increased significantly (P < 0.01) on admission to the ICU (t0) compared with the preoperative levels, but levels returned to normal within 6 h and remained so for the rest of the study. There was a significant difference between survivors and non-survivors at t0 (P < 0.01). However the ROC curve indicated that M:Cr is not a reliable descriptor of outcome. Comparison of Cr values with the PaO2/FiO2 ratio showed an inverse relationship on admission, which remained so for t24 and t48.

CONCLUSION

M:Cr measured on admission to the ICU was significantly higher in non-survivors than in survivors, and also showed an inverse relationship with the PaO2/FiO2 ratio following extended abdominal surgery. However, on admission, M:Cr did not discriminate survivors from non-survivors. Further studies are required to evaluate the prognostic value of this test for postoperative patients with risk of respiratory failure.

Glomerular permeability after surgical trauma in children: relationship between microalbuminuria and surgical stress score

OBJECTIVES

To determine whether there is an increase of urinary albumin during and after surgical trauma and investigate a possible relationship between microalbuminuria and the severity of surgical stress.

DESIGN

Prospective study.

SETTING

University hospital pediatric intensive care unit.

PATIENTS

Forty consecutive children scheduled for elective surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Microalbuminuria/urinary creatinine ratio (MACR) was measured before, during, and after elective moderate or major surgical procedures. The Oxford Surgical Stress Score (SSS) was determined for each patient at the end of the operation, and its relationship with maximum deviation of MACR from baseline values was investigated. MACR showed a progressive increase during surgery and a decrease afterward, reaching preoperative values in most cases within 24 hrs after the end of surgery. There was a significant correlation between the increase in MACR and severity of the surgical trauma as measured by SSS. Two patients showed a rise in MACR after the initial postoperative normalization before clinical appearance of a surgical complication and one patient showed a persistent rise in MACR before clinical appearance of a septic complication. None of the other patients showed any rise in MACR after postoperative normalization, and they all had an uneventful recovery.

CONCLUSIONS

MACR rises during and after major or moderate elective surgery in children. There is a significant positive correlation between severity of surgical trauma and capillary permeability in pediatric patients. Microalbuminuria, as an index of capillary permeability, may be an early sign of incipient complications and assist in the identification of those patients whose condition will deteriorate. The test is a cheap, blood-sparing, easy-to-perform bedside procedure that may have a useful role in clinical practice for evaluating the effect of surgical trauma on capillary permeability in children.

Glomerular permeability and trauma: a correlation between microalbuminuria and Injury Severity Score

OBJECTIVE

To determine if there is a correlation between an increase in glomerular permeability, the magnitude of trauma, and the severity of illness.

DESIGN

Prospective study.

SETTING

Two university hospital intensive care units.

PATIENTS

Forty consecutive critically ill trauma patients admitted directly to the intensive care unit within 120 mins of their injuries.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For each patient, urine was collected from the time of admission until 7 am the next day. Within 48 hrs, only one sample of all urine collected (5 mL) was examined for microalbuminuria and urinary creatinine. Results were expressed as the microalbuminuria/urinary creatinine ratio (MACR). The mortality rate in the intensive care unit, Injury Severity Score at the moment of admission, Acute Physiology and Chronic Health Evaluation III score, and Simplified Acute Physiology Score in the first 24 hrs were calculated for each patient. The data were analyzed using the Pearson test for linear regression and Student's t-test. During the first 24 hrs after trauma, there was an increase of MACR (6.9 +/- 0.6 mg/mmol) above normal (reference range, <3 mg/mmol) that was positively correlated with Injury Severity Score (31.4 +/- 1.9; r2 = .73, p < .05). However, there was no correlation between MACR, Acute Physiology and Chronic Health Evaluation III score, Simplified Acute Physiology Score, and mortality rate.

CONCLUSIONS

Patients with trauma show an increase in glomerular permeability during the first 24 hrs after injury. The magnitude of this increase is correlated with the extent of trauma but does not seem significant enough to be predictive of severity of illness and/or outcome.