Effects of lipo-prostaglandin E1 on random pattern flaps in rabbits

Effects of Prostaglandin E1 on Mastectomy Flap Necrosis in Immediate Implant-Based Breast Reconstruction

BACKGROUND

Necrosis of a cutaneous flap including the nipple-areola complex is a common complication in immediate implant-based breast reconstruction following nipple-sparing mastectomy (NSM)/skin-sparing mastectomy (SSM). This study aimed to evaluate the efficacy of prostaglandin E1 (PGE1) in reducing such complications.

METHODS

A retrospective analysis of prospectively collected data was conducted at two centers, and the cohort consisted of patients undergoing NSM/SSM followed by immediate reconstruction with a prosthesis. Patients who were randomly allocated to the treatment group were administered daily intravenous PGE1 (10 μg/2 mL) beginning intraoperatively through postoperative day 6. Skin flap complications including nipple/skin necrosis, delayed wound healing, and postoperative wound revision were recorded. Complication rates were compared between the PGE1 and control groups.

RESULTS

A total of 276 breasts in 259 patients were included for analysis (139 breasts in the treatment group and 137 breasts in the control group). There was no difference in patient demographics between the control and treatment groups. Reconstructed breasts receiving PGE1 had significantly lower rates of overall skin complications (21.6% versus 34.3%; P = 0.022) and wound revision (2.9% versus 9.5%; P = 0.025). Among NSM cases, the PGE1 group showed a significantly lower rate of nipple necrosis (15.5% versus 29.4%; P = 0.027). In the multivariate analysis, the use of PGE1 significantly reduced the risk of overall skin flap complications (OR, 0.491; P = 0.018) and wound revision (OR, 0.213; P = 0.018) in NSM/SSM cases, and nipple necrosis (OR, 0.357; P = 0.008) in NSM cases.

CONCLUSION

PGE1 can be effective in reducing risk of mastectomy flap complications in immediate implant-based breast reconstructions.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Prostaglandin E1 Increases Microcirculation in Random Pattern Flaps on Rats Measured with Laser Doppler Perfusion Imaging

Background:

Reconstructive procedures with pedicled and free flaps are associated with a risk of ischemia. Prostaglandin E1 (PGE1) is a hormone-like substance with known antiischemic and tissue-protective effects. The aim of this study was to evaluate the effect of PGE1 on the microcirculation in random pattern skin flaps on rats.

Methods:

Twenty-four rats were divided into 2 groups: an intervention group given PGE1 for 6 hours and a control group given saline. The flap (2 × 10 cm) was created on the back of the rats, and the microcirculation was monitored with laser Doppler perfusion imaging in 5 different zones (1, proximal; 5, distal) before surgery and after 60, 180, and 360 minutes postoperatively.

Results:

Before surgery, there was no difference in the perfusion in any zones between the intervention group and the control group. The mean perfusion values in zone 1 in the intervention group were significantly higher than those in the control group at 60, 180, and 360 minutes postoperatively (P = 0.02, P = 0.05, and P = 0.04, respectively). At 360 minutes, we also found significantly higher levels of perfusion in the intervention group in zones 4 and 5 (P = 0.05 and P = 0.03, respectively) compared with the controls. Comparing the perfusion at 360 to 60 minutes in the intervention group, we found a significant increase in microcirculation in all zones, which were not seen in the control group.

Conclusion:

PGE1 increased perfusion in the dermal random pattern flaps on rats.

The Comparison Study of Lipo PGE1 Preparations

The comparison study was performed with 3 kinds of Lipo PGE(1) (5 microg/ml) preparations (Formulation A, B, and C), which are now used in clinical. Under alkali condition, Lipo PGE(1) (5 microg/ml) preparations in combination with physiological solution containing calcium ion were susceptible to stop dropping because of the formation of aggregates. There was a difference of feasibility to form aggregates among these preparations. The percentage of PGE(1) in the LM (lipid microspheres) was 68.8% (Formulation A) when determined by filtration with the pore size of 0.1 microm, and the respective value (%) of Formulation B and Formulation C was 43.0% and 13.9%. This indicates that the latter formulations were significantly susceptible to leak from the LM. PGE(1) can induce an extensive irritation. The potency of irritation was the most in Formulation C. This seems similar with the result of LM retention of PGE(1). PGE(1) increased the blood flow. Formulation A reached the peak by 2.27 fold, which was significantly higher than Formulation C and PGE(1) alone (PGE(1)-cyclodextrin, PGE(1)-CD). The peak was also significantly higher in Formulation B than that of PGE(1)-CD. The AUC value of blood flow rate showed a significant increase in Formulation A and Formulation B as compared to that of PGE(1)-CD. Drug retention in the LM can be a determinant factor for drug distribution and pharmacological effect. This study indicates that there can be some differences among Lipo PGE(1) preparations, which have the same drug dose.

Liposomal prostaglandin E1 enhances optic nerve head blood flow in cats

We investigated the effects of intravenous administration of prostaglandin E1 (PGE1) and lipo-prostaglandin E1 (lipo-PGE1), on optic nerve head blood flow (ONHBF) using ten anesthetized cats. Changes in relative ONHBF were noninvasively and continuously measured with fundus camera-based laser Doppler flowmetry. The blood pressure (BP) decreased significantly by 6 +/- 5 (mean +/- SD)% and 8 +/- 4%, respectively, after PGE1 (30, 100 ng/kg/min) administration, but at either of these concentrations there were no significant changes in ONHBF. On the other hand, with lipo-PGE1 (10 ng/kg/min), the BP remained unchanged, but ONHBF increased significantly by 61 +/- 49%. A larger dose of lipo-PGE1 (30 ng/kg/min) had opposite effects because the BP decreased significantly by 14 +/- 4% after administration, and the ONHBF remained unchanged (i.e., 67 +/- 102%). In all cases, there were no changes in IOP. With 10 ng lipo-PGE1, the large increase in ONHBF can be accounted for by vasodilation since perfusion pressure was unchanged. The inability of 30 ng lipo-PGE1 to affect ONHBF could be ascribed to the decrease in BP resulting in decreased ocular circulation. These results suggest that, in humans, lipo-PGE1 may also increase ONHBF provided that it is used at doses that do not produce large decreases in BP.

Specific augmentation of plantar skin blood flow by lipo-PGE1 assessed in tetrodotoxin- and N(G)-nitro-L-arginine-treated rats

1Vasodilating effects of prostaglandin E1 incorporated in lipid microspheres (lipo-PGE1) were compared with those of prostaglandin E1 (PGE1) or its cyclodextrin clathrated preparation (PGE1-CD) on plantar skin blood flow in rats treated with tetrodotoxin and N(G)-nitro-L-arginine (L-NNA). Tetrodotoxin (50 microg/kg, i.v.) could totally inhibit the pressor response to electrical stimulation of the spinal cord, and the reflex tachycardia due to the depressor response to acetylcholine. Furthermore, L-NNA (30 mg/kg, i.v.) was used to counteract the lowering of the systemic blood pressure and peripheral vascular tone by elimination of sympathetic nerve activity, and to maintain the arterial blood pressure at the control level. Lipo-PGE1 increased plantar skin blood flow 4 to 6 times more potently than PGE1-CD or PGE1 in the treated rats. Furthermore, lipo-PGE1 increased plantar skin blood flow about 3 times more selectively than PGE1-CD. We also assessed several vasodilators, including terbutaline, nitroprusside, nicardipine, and papaverine in tetrodotoxin- and L-NNA-treated rats. However, none of them could selectively increase plantar blood flow despite the prominent depressor responses achieved. These results suggest that PGE1 preparations, especially lipo-PGE1 could potently and selectively increase plantar skin blood flow in rats treated with tetrodotoxin and L-NNA.