Comparison of the Effectiveness of Mitomycin-C and Viscoat on Delayed Adjustable Strabismus Surgery in Rabbits

Purpose

To determine a way to prevent the formation of adhesions and delay the time of suture adjustment in the course of adjustable strabismus surgery, an animal study was performed to assess and compare the effects of mitomycin C (Mit-C) and viscoelastic material Viscoat (sodium hyaluronate 3% and chondroitin sulphate 4%, Alcon, Fort Worth, TX).

Methods

Right eyes of 47 rabbits were divided into three groups. After recession of the superior rectus muscle (SRM), Mit-C was administered beneath and over the SRM in Group M (16 eyes), Viscoat was administered beneath and over SRM in Group V (16 eyes), and ringer lactate was administered in Group C (15 eyes). SRM then recessed 5 mm with adjustable strabismus surgery technique. Animals in each group were subdivided into 1 and 2, where 1 = adjustment 1 week postoperatively and 2 = adjustment 3 weeks postoperatively. Delayed adjustment was performed in M1 group (6 eyes), V1 group (6 eyes), and C1 group (7 eyes) after 1 week; in M2 group (6 eyes), V2 group (6 eyes), and C2 group (6 eyes) after 3 weeks. Histopathologic examinations were performed for the remaining 10 eyes without suture adjustment at the end of first and third weeks after adjustable strabismus surgery. The possible length and the necessary force to adjust and the degree of adhesions were recorded.

Results

When length and strength of the adjustment, adhesions between muscle and sclera, and adhesions between muscle and conjunctiva were taken into consideration, there was no statistically significant difference among M, V, and C groups at postoperative weeks 1 and 3. The force needed for adjustment in M1 group was statistically lower than M2 group.

Conclusions

The intraoperative use of Mit-C (0.4 mg/mL) may decrease adhesion formation in the early postoperative period, especially in the first week. The intraoperative use of Viscoat was not effective in reducing postoperative adhesions and delaying adjustment.

Comparison of the effectiveness of mitomycin-C and Viscoat on delayed adjustable strabismus surgery in rabbits

PURPOSE

To determine a way to prevent the formation of adhesions and delay the time of suture adjustment in the course of adjustable strabismus surgery, an animal study was performed to assess and compare the effects of mitomycin C (Mit-C) and viscoelastic material Viscoat (sodium hyaluronate 3% and chondroitin sulphate 4%, Alcon, Fort Worth, TX).

METHODS

Right eyes of 47 rabbits were divided into three groups. After recession of the superior rectus muscle (SRM), Mit-C was administered beneath and over the SRM in Group M (16 eyes), Viscoat was administered beneath and over SRM in Group V (16 eyes), and ringer lactate was administered in Group C (15 eyes). SRM then recessed 5 mm with adjustable strabismus surgery technique. Animals in each group were subdivided into 1 and 2, where 1 = adjustment 1 week postoperatively and 2 = adjustment 3 weeks postoperatively. Delayed adjustment was performed in M1 group (6 eyes), V1 group (6 eyes), and C1 group (7 eyes) after 1 week; in M2 group (6 eyes), V2 group (6 eyes), and C2 group (6 eyes) after 3 weeks. Histopathologic examinations were performed for the remaining 10 eyes without suture adjustment at the end of first and third weeks after adjustable strabismus surgery. The possible length and the necessary force to adjust and the degree of adhesions were recorded.

RESULTS

When length and strength of the adjustment, adhesions between muscle and sclera, and adhesions between muscle and conjunctiva were taken into consideration, there was no statistically significant difference among M, V, and C groups at postoperative weeks 1 and 3. The force needed for adjustment in M1 group was statistically lower than M2 group. CONCLUSIONS. The intraoperative use of Mit-C (0.4 mg/mL) may decrease adhesion formation in the early postoperative period, especially in the first week. The intraoperative use of Viscoat was not effective in reducing postoperative adhesions and delaying adjustment.

Randomized trial of traditional dissection with electrocautery versus ultrasonic fundus-first dissection in patients undergoing laparoscopic cholecystectomy

BACKGROUND

In laparoscopic cholecystectomy dissection can be with monopolar electrocautery or with ultrasonic shears, and can start at the triangle of Calot or at the fundus of the gallbladder.

METHODS

Thirty-seven patients undergoing laparoscopic cholecystectomy were randomized to electrocautery dissection from the triangle of Calot and 43 to fundus-first dissection with ultrasonic shears. All procedures were strictly standardized, and patients and their postoperative carers were blinded to the operation performed.

RESULTS

Ultrasonic fundus-first dissection was associated with a shorter duration of operation (mean 46 versus 61 min), fewer overnight hospital stays (two versus eight), lower pain scores 4 and 24 h after surgery, less nausea at 2, 4 and 24 h, and a shorter period of sick leave (mean 5.5 versus 9.3 days) compared with electrocautery from the triangle of Calot.

CONCLUSION

Ultrasonic fundus-first dissection during laparoscopic cholecystectomy was quicker and associated with less nausea and pain than electrocautery dissection from the triangle of Calot.

Randomized clinical trial of the use of a prosthetic mesh to prevent parastomal hernia

BACKGROUND

Parastomal hernia is a common complication following colostomy, and repair with a prosthetic mesh is associated with the lowest recurrence rate. The aim of this study was to determine the effect on stoma complications of using a mesh at the primary operation.

METHODS

Patients undergoing permanent colostomy were randomized to have either a conventional stoma or the addition of a mesh placed in a sublay position. A large-pore lightweight mesh with a reduced polypropylene content and a high proportion of absorbable material was used.

RESULTS

Twenty-seven patients were randomized to have a conventional stoma and 27 to have the mesh. No infection, fistula formation or pain occurred (observation time 2-28 months). At the 12-month follow-up, parastomal hernia was present in eight of 18 patients without a mesh and in none of 16 patients in whom the mesh was used.

CONCLUSION

A lightweight prosthetic mesh in a sublay position at the stoma site was not associated with infection or other early complications. Preliminary results indicate that the mesh prevented the development of parastomal hernia.

Small tissue bites and wound strength: an experimental study

HYPOTHESIS

Placing stitches close to the cut wound edge does not produce low wound bursting strength in midline laparotomy incisions closed with a suture length:wound length ratio of 4.

DESIGN

Experimental study in rats.

METHODS

Midline incisions were closed with a running suture in 51 Sprague-Dawley rats. A suture length:wound length ratio of 4 was used and stitches were placed at a distance of 3, 6, or 10 mm from the wound edge. Wound bursting strength was studied immediately after and 4 days after wound closure.

RESULTS

Immediately after wound closure, bursting pressure was higher with stitches placed 10 mm from the wound edge than those at a distance of 3 mm. After 4 days, bursting pressure and bursting volume were lower with stitches placed 10 mm from the wound edge than those at a distance of 3 or 6 mm. The abdominal wall ruptured outside the suture line in 14 of 17 wounds closed with 21 stitches, in 11 of 17 wounds closed with 16 stitches, and in 6 of 17 wounds closed with 11 stitches (P=.02).

CONCLUSIONS

Four days after closure of midline laparotomy incisions using a suture length-wound length ratio of 4, wound bursting strength is higher with stitches placed 3 to 6 mm from the wound edge than those at a distance of 10 mm. Wound bursting strength increases with the number of stitches used.

Mass closure technique: an experimental study on separation of wound edge

OBJECTIVE

To study separation of wound edges in midline laparotomy incisions closed with either a mass stitch or a stitch incorporating only aponeurosis.

DESIGN

Experimental study in pig.

SETTING

University hospital, Norway.

ANIMALS

8 domestic pigs.

METHODS

Steel sutures were used and metallic clips were placed in the aponeurosis. After increasing the intra-abdominal pressure the distance between the lateral edge of stitches and between pairs of clips was measured on sequential radiographs.

RESULTS

After three hours with raised intra-abdominal pressure the lateral edge of stitches became separated by a mean (SD) of 5.6 (1.3) mm with a mass stitch and by 0.5 (0.6) mm with stitches placed only in the aponeurosis (p < 0.001). Corresponding figures for separation of clips was 3.6 (1.5) mm and 0.1 (0.3) mm (p < 0.001). The suture cut through the muscle by more than 3mm in 25 out of 36 mass stitches. Muscle and peritoneum included in the mass stitch was compressed, darkly discoloured, and there were signs of haemorrhage.

CONCLUSIONS

Wound edges become separated with a mass stitch but not with stitches placed only in the aponeurosis when the intra-abdominal pressure is raised after closure of midline laparotomy incisions. This results from sutures compressing or cutting through subcuticular fat, muscle, and peritoneum enclosed in a mass stitch.

Conventional running suture and continuous double loop closure: an experimental study of wound strength

OBJECTIVE

To study the strength of laparotomy wounds closed by a continuous double loop technique or a conventional running suture, taking into account the ratio of suture length: wound length.

DESIGN

Experimental study.

ANIMALS

60 Sprague-Dawley rats.

INTERVENTIONS

Midline laparotomy incisions were closed with either a conventional running suture or a continuous double loop. Wounds were allocated to closure with a suture length: wound length ratio of 3, 4 and 7.

MAIN OUTCOME MEASURES

Bursting pressure, bursting volume and the way the suture cut through the tissues.

RESULTS

With a suture length: wound length ratio of 3 or 4 bursting pressure and bursting volume were lower with a continuous double loop closure. A conventional running suture and a continuous double loop produced similar bursting pressure and bursting volume only if closure was with a ratio of 7.

CONCLUSIONS

Wound bursting strength is higher with a conventional running suture than with a continuous double loop closure when the effect of the suture length: wound length ratio is accounted for.