Desmopressin and bleeding during invasive surgery

The effects of intermittent prebypass heparin dosing in patients undergoing coronary artery bypass grafting

In this study, 10 patients (Group B) were given three consecutive prebypass doses of heparin (100 IU/kg) with a 4 min interval prior to cardiopulmonary bypass (CPB) institution. They were compared with 10 patients (Group A) receiving the standard single prebypass heparin dose (300 IU/kg). The haemostatic response and anticoagulant monitoring during the perioperative period were investigated by point-of-care and several coagulation tests. Results of both groups were also correlated to blood loss. Three patients in Group B required additional heparin during bypass as compared with six patients in Group A. This suggests that intermittent prebypass heparin dosing is more effective in maintaining adequate levels of anticoagulation during CPB. Group B had a lower mean decrease in factor VIII (13.9% versus 43.2%), fibrinogen (38.5% versus 46.6%), antithrombin III (34.7% versus 40.1%) and platelet count (23.2% versus 28.9%) during bypass while only one unit of red cell concentrate was required postoperatively as compared with four units in Group A. In one patient, high fibrinolytic assays were associated with a haemorrhagic pericardial effusion occurring beyond 24 hours postsurgery.

Desmopressin does not decrease blood loss and transfusion requirements in patients undergoing hepatectomy

PURPOSE

To determine the effects of desmopressin on coagulation and blood loss in patients undergoing elective partial hepatectomy.

METHODS

A randomized, controlled and double-blind study on 59 patients who received either 0.3 micro g x kg(-1) of desmopressin or an equal volume of normal saline (control) infused intravenously over 20 min after induction of general anesthesia.

RESULTS

There was an increase in plasma levels of factors VIII and von Willebrand after the infusion of study drug in both groups (P < 0.001). The activated partial thromboplastin time was shortened in Group D whereas prothrombin time was prolonged in Group C; (P = 0.02). A large range of intraoperative blood loss (400-7128 mL) was observed, with no significant differences between groups. There were no changes in plasma electrolyte levels or osmolality. Transfusion requirements were similar in both groups.

CONCLUSION

Desmopressin did not reduce intraoperative blood loss or transfusion requirements during hepatectomy despite raising clotting factor levels and improving tests of hemostasis.

Desmopressin impairs microcirculation in donor pancreas and early graft function after experimental pancreas transplantation

BACKGROUND

Protective effects of desmopressin in brain dead organ donors oppose reports on a hypercoagulatory potential and an increased leukocyte-endothelial interaction (LEI) after application of the drug. The aim was to evaluate the effect of desmopressin on organ donor's pancreas and early graft function.

METHODS

Donor microcirculation was evaluated via intra-vital microscopy (IVM) in 24 BR (di/di) rats with central diabetes insipidus, randomly assigned to groups I (control without desmopressin application), II (single i.v. application, no pretreatment) or group III (single i.v. desmopressin application, s.c. pretreatment for 3 days). Microcirculation in recipients was evaluated 1 hr and 6 hr after syngenic pancreas transplantation. Groups III and I served as organ donors. After IVM specimens were taken for histology and immunohistochemistry.

RESULTS

Desmopressin in II vs. I led to temporarily (30') increased LEI (Sticker 274.3+/-87.7 vs. 76.5+/-31.1/mm2 endothelial surface; P<0.01) and impaired microcirculation (MCEV 0.43+/-0.07 vs. 0.99+/-0.06 mm/s; P<0.01). Repeated application reduced MCEV and increased LEI for up to 12 hr. Histology in I vs. III showed increased inflammation (n.s.), necrosis (P<0.05) and vacuolization (P<0.01). Immunohistochemistry revealed increased endothelial P-selectin 20' after application. 6 hr after reperfusion organs from III showed reduced MCEV and increased LEI (P<0.01).

CONCLUSION

Repeated application of desmopressin impairs graft microcirculation. Perfusion of the pancreas is significantly reduced at the beginning of organ tissue conservation as well as after reperfusion. These disturbances might partly be due to observed endothelial P-selectin expression. Application of desmopressin up to 12 hr prior to organ explantation may impact graft quality.

Non-sequential vasopressin peptides. Stereochemistry and biological activity

Two cyclic disulfides of structure Cys-Tyr-Arg-Arg-Tyr-Cys-NH2 (1) and Cys-Tyr(Me)-Arg-Arg-Tyr(Me)-Cys-NH2 (2), two nonapeptide derivatives of 1 extended at the C-terminal with Pro-Arg-Gly-NH2 (3) or Pro-D-Arg-Gly-NH2 (4) and derivatives of 3 and 4 having Mpr in position 1, i.e. analogs (5) and (6), respectively, were synthesized, and their stereochemistry and biological activity were studied. All the peptides displayed low dose-dependent uterotonic activity in vitro and antidiuretic activity in vivo. None of the peptides increased the blood pressure of the experimental animals. Compounds 2, 4 and 6 showed a low inhibitory effect on AVP pressor activity; compound 6, in addition, displays a significant and long-lasting vasodepressor effect. NMR measurements indicated the existence of hydrogen bond between the amino acid residues in positions 2,5 and 3,4 of peptides 1 and 2, and side-chain interactions between amino acid residues in positions 2,3 and 4,5 of peptide 1. No such side-chain interactions were detected in peptide 2.