cc1032 CCJ Meeting abstract <p>Beating heart coronary surgery and renal function: a prospective randomised study</p> Tang ATM Thomas R Knott J Nanson J Ohri SK Smith D

Departments of Anaesthesia

Cardiac Surgery, Southampton General Hospital, Southampton, UK

 Critical Care <p>18th Spring Meeting of the Association of Cardiothoracic Anaesthetists</p> Supported by an unrestricted educational grant from Bayer plc Meeting abstracts <p>18th Spring Meeting of the Association of Cardiothoracic Anaesthetists</p> Cambridge, UK 22 June 2001 1364-8535 2001 5 Suppl C 3 10.1186/cc1032 3 7 2001 2001 BioMed Central Ltd cc-5-4-236-03

Introduction

Cardiopulmonary bypass (CPB) is widely regarded as an important contributor to renal failure, a well recognised complication, following coronary artery surgery (CABG). Off-pump coronary surgery (OPCAB) is intuitively considered renoprotective. We examine the extent of renal glomerular and tubular injury in low-risk patients undergoing either OPCAB or on-pump coronary artery bypass (ONCAB).

Methods

Forty patients awaiting elective CABG were prospectively randomized into those undergoing OPCAB (n = 20) and ONCAB (n = 20). Table 1 illustrates the exclusion criteria. Glomerular and tubular injury were assessed, respectively, by urinary excretion of microalbumin and retinol binding protein (RBP) indexed to urinary creatinine [1]. Daily measurements were made from admission to postoperative day 5. Fluid balance, serum creati-nine and blood urea were also monitored.

<p>Table 1</p>

Exclusion criteria

Pre-existing renal disease

Age above 80 years

Serum creatinine above 135 μmol/L

Unstable angina

LV ejection fraction less than 40%

Regular usage of nephrotoxic

agents

Chronic or uncontrolled hypertension

Perioperative inotrope

dependency

Diabetes mellitus

Results

No mortality or renal complication was observed. Both groups had similar demographic make-up. The OPCAB group received fewer coronary grafts than their counterparts (1.8 versus 2.8; P = 0.002). Serum creatinine and blood urea remained normal in both groups throughout the study. A dramatic and similar rise in mean ± 2SD urinary RBP:creatinine ratio occurred in both groups peaking on day 1 (3183 ± 2534 versus 4035 ± 4078; P = 0.43) before returning to baseline levels. These trends were also observed with the urinary microalbumin:creatinine ratio (5.05 ± 2.66 versus 6.77 ± 5.76; P = 0.22). ONCAB patients had a significantly more negative fluid balance on postoperative day 2 (-183 ± 1118 versus 637 ± 847 ml; P < 0.05).

Conclusions

Although renal dysfunction did not clinically occur in any patient, sensitive indicators revealed significant and similar injury to both renal tubules and glomeruli following either OPCAB or ONCAB. These suggest that avoidance of CPB per se does not offer additional renoprotection to patients at low risk of perioperative renal insult during CABG.

 <p>The effect of 'renal-dose' dopamine on renal tubular function following cardiac surgery: assessed by measuring urinary retinol binding protein.</p> Tang A El-Gamel A Keevil B Yonan N Deiraniya A Eur J Cardiothorac Surg 1999 15 717 10.1016/S1010-7940(99)00081-0 10386423