Amikacin concentrations in serum following intraoperative irrigation of the pleura and peritoneum.

Serum concentrations of amikacin following operative wound irrigation were studied in 17 patients having laporatomy and in eight patients having thoracotomy. Irrigation was done with 500 mg of amikacin in 200 ml of saline. The irrigant was reaspirated after 3 minutes. Measurement of amikacin in the irrigant allowed calculation of the retained dose. Serum levels were measured before surgery, and at 30 minutes, 60 minutes, 6 hours, and 12 hours following irrigation. Amikacin was assayed by a microbiological technique. The retained dose after peritoneal irrigation was 350 +/- 128 mg, and after pleural irrigation was 100 +/- 79 mg. The average maximum serum level in the peritoneal irrigation group was 9.4 +/- 6.7 gm/ml; in the thoracotomy group it was 3.5 +/- 1.7. Fourteen of the 17 laparotomy patients but only one of the eight thoracotomy patients had measurable plasma levels at 6 hours. Plasma half-life in the laparotomy group was 2.81 +/- 1.34 hours, and in the thoracotomy group 1.53 +/- 0.83 hours. Interoperative amikacin irrigation, even with immediate aspiration, results in significant absorption in both thoracotomy and laporatomy patients. There was less absorption and a shorter serum half-life in the thoracotomy patients.