Plasmatic vasopressin in patients undergoing conventional infra-renal abdominal aorta aneurysm repair

To evaluate plasmatic arginine vasopressin (AVP) levels in patients undergoing scheduled conventional abdominal aortic aneurysm (AAA) repair.

Plasmatic AVP concentrations were measured by radioimmunoassay in 22 non-consecutive adult patients undergoing infra-renal AAA repair. They were under combined general and epidural anesthesia at the following time frames: 1--pre-operative (T0); 2--2h (T1) and 6h (T2) after the surgical procedure; 3--in the morning at the first (T3), second (T4) and third (T5) post-operative days. Some clinical and laboratory variables were also recorded.

The mean age of patients was 68 ± 10 years; 17 were males. Plasmatic AVP (mean ± SD; pg/mL) was within the normal range at T0 (1.4 ± 0.7; baseline), increasing significantly at T1 (62.6 ± 62.9; P<0.001) and at T2 (31.5 ± 49.7; P<0.001), with a progressive fall, returning to basal levels at T5 (2.1 ± 3.8; P = NS). Positive and statistically significant correlations were found between AVP and glycemia, serum lactate and white blood cells counts, but not with systemic arterial pressure or plasma osmolarity during the postoperative period.

Considering that no correlations were found between AVP levels and hemodynamic or plasmatic osmolarity variations in AAA repair, it seems that stress response is mainly secondary to noxious stimulation mediated by the autonomic nervous system that is not completely blocked by anesthetics.