Postgraduate Medical Journal (March 1977) 53, 122-125. Postgrad Med J: first published as 10.1136/pgmj.53.617.122 on 1 March 1977. Downloaded from A study of the effect of povidone-iodine on wound healing 0. J. A. GILMORE CLARE REID M.S., F.R.C.S., F.R.C.S.Ed. B.Sc., A.I.M.L.S. A. STROKON F.R.C.S.Ed. Surgical Professorial Unit, St Bartholomew's Hospital, London E.C.I and North Middlesex Hospital, London N.18 Summary of a substance other than pus' (Pollock, 1973). The effect of dry powder povidoneiodine (Disadine For this reason the clinical evaluation was under- D.P.) on wound healing was assessed experimentally taken in patients undergoing elective, 'clean', and clinically. It did not interfere with wound healing non-abdominal operations. macroscopically, histologically or mechanically in Wistar rats. One hundred and one patients undergoing Materials and methods 'clean' elective surgery were included in the controlled Experimental study clinical study and povidone-iodine did not affect Seventy-two female, specific pathogen-free, Wistar wound healing in any way. In the control group 4% rats weighing 220-250 g were used in this study.Protected by copyright. of patients developed infection compared with none Under ether anaesthesia following shaving and skin of those sprayed with povidone-iodine. No adverse disinfection with chlorhexidine gluconate 0-5% in reaction to povidone-iodine was seen in either study. 70% methylated spirit, a 4-cm, vertical, mid-line This antiseptic offers a safe alternative to antibiotics incision was made through all layers of the anterior for use at operation whenever there is risk of wound abdominal wall. A card was then drawn allocating infection from operative bacterial contamination. the rat to one of two groups. The wounds of the thirty-six rats in group A remained as untreated Introduction controls. The open wounds of the thirty-six rats in Interparietal, dry powder povidone-iodine (Disa- group B were sprayed with dry powder povidone- dine D.P.) sprayed into the wound just before iodine (Disadine D.P.) for 5 sec, from a distance of closure significantly reduces infection after potenti- approximately 25 cm. All wounds were closed in ally contaminated abdominal operations (Gilmore one layer with seven interrupted 2/0 black silk and Sanderson, 1975). It reduces wound infection sutures, each separated by a gap of 0-5 cm. http://pmj.bmj.com/ after gridiron appendicectomy and is at least as effective as a polyantibiotic spray containing Assessment of wound healing neomycin, bacitracin and polymixin (Gilmore, Wound healing was assessed macroscopically, Martin and Fletcher, 1973; Gilmore and Martin, histologically and mechanically in ignorance of the 1974). Numerous antiseptics, however, damage treatment group. the tissues and inhibit healing (Branemark and Macroscopic assessment was made in six rats per Ekholm, 1967). Pollock and Evans (1975) suggested group at 3, 5, 7, 14 and 28 days after operation. that povidone-iodine acted as a wound irritant and Wounds were inspected for inflammation, excoria- on September 29, 2021 by guest. caused secondary sepsis. tion and wound and stitch abscess formation. An experimental study using rats was therefore Histological assessment was made in three rats per carried out to determine the effect of povidone- group at 7 and 28 days after operation. Following iodine on wound healing, and a clinical trial deter- killing with ether a rectangle of anterior abdominal mined whether it causes secondary sepsis. Late wall measuring 2 x 1 cm was excised from each rat in wound infections often occur after potentially such a way that there was 1 cm of tissue either side of contaminated abdominal procedures (Gilmore and the healing incision. Sections were stained with Martin, 1974; Gilmore and Sanderson, 1975) and haematoxylin and eosin and examined under high cannot always be differentiated from secondary and low power magnification. sepsis 'that which follows discharge from the wound Mechanical assessment was carried out in six rats Correspondence: Mr 0. J. A. Gilmore, St Bartholomew's per group at 3, 5, 7, 14 and 28 days after operation. Hospital, West Smithfield, London EC1A 7BE. The bursting strength of the abdominal wound was Povidone-iodine and wound healing 123 Postgrad Med J: first published as 10.1136/pgmj.53.617.122 on 1 March 1977. Downloaded from measured in the manner described by Prudden, the patient returned home was included in the in- Nishihara and Baker (1957) and de Haan, Ellis and fected group. Wilks (1974). The rats were killed with ether; any remaining sutures were then carefully divided but not Statistical methods removed. A pair of Spencer Wells forceps was The mean bursting pressure of the rat abdomen inserted into the peritoneal cavity through a defect was calculated for each treatment group on each day made in the apex of the vagina. A fingercot (Regent of killing. These means were compared using an Medical Fingercot. L.R.I. Ltd) was then inserted via unpaired Student's t-test with standard deviation. the same route and connected by a 'Y' junction to a The same test was used in the clinical study for mercury manometer and a cylinder of carbon di- comparison of continuous variables, i.e. age, oxide. The pressure was raised at a constant rate of duration of operation and length of incision. The 5 mmHg/sec until the abdomen burst. X2 test was used for two analyses: distribution of patients between the two treatment groups according Clinical study to build and the number of patients in each group One hundred and one consecutive patients at the operated on by individual surgeons. Fisher's exact North Middlesex Hospital, London, undergoing test (Fisher, 1935) was used to analyse data related elective, 'clean', non-abdominal operations were to the patient's sex and the type of operation. included in this study. Random allocation of patients to one of two groups was achieved by using a table Results of random numbers; the code in the form of an Experimental study 'Advent Calendar' was kept outside the theatre. The Macroscopic assessment. The wounds were found surgeon was informed of the spraying procedure to to be soundly healed in all rats sprayed with povi- be used before he started the wound. The done-iodine. In the control two rats had areas just closing group Protected by copyright. open wounds of patients in group S were sprayed of excoriation in the vicinity of the wound, three with dry powder povidone-iodine and the wounds of had wound abscesses and one a stitch abscess. Two the patients in group T with the propellant alone rats in the povidone-iodine group had evidence of (dichlorodifluoromethane and trichlorofluorometh- superficial infection and one had a bead of pus at a ane). Spraying was carried out by the runner nurse or stitch site. There was no evidence of reaction to the theatre technician who, having shaken the aerosol, povidone-iodine in any rat. sprayed the open wound for 10 sec from approxi- Histology. At 1 week there was hyperplasia of the mately 25 cm. The deeper layers of all wounds were epidermis in all specimens. Granulation tissue was closed with chromic catgut and the skin with inter- visible between the divided dermis, subcutaneous rupted 2/0 black silk. All closed wounds were tissue and panniculus carnosus. Macrophages, sprayed with nobecutane, no other dressing being foreign body giant cells and some polymorphonuc- applied. lear cells were visible in both groups around hairs A standard form was completed at the end of each and suture material in the interparietal granulation operation recording the patient's age, sex, diagnosis tissue. These changes were no more marked in one http://pmj.bmj.com/ and build. Patients with less than 1 cm of sub- group than the other. cutaneous tissue were classified as thin, those with It was equally difficult to see the incision his- 1-2-5 cm as average and those with more than 2-5 cm tologically in all rats at 1 month. The sites of the as obese. The operative procedure, the type of divided rectus muscles were visible and were joined incision, its length, the duration of the operation, by new muscle and fibrous tissue in similar propor- the surgeon, and whether the patient was given tions in both groups. A layer of fibrous tissue was antibiotics were also recorded. visible in all animals between the muscle and healing on September 29, 2021 by guest. All wounds were inspected in ignorance of the the healed peritoneum. Although examination of spraying procedure used by the registrar from the the sections taken from the incisions at 1 week and 1 firm which had not performed the operation. A month showed some individual variations in careful watch was kept for evidence of inflammation, appearance, there was no consistent change in one excoriation, discharge and local or general reactions. group. The criteria of Ljungquist (1964) were adopted with Burstingpressures. The mean bursting pressures of regard to infection. The wound was either clean or the abdominal wounds of the rats in both groups on infected. It was infected if at any time a purulent the different days are shown as a histogram in Fig. 1. discharge occurred. If a serous discharge appeared When these are compared there is no statistical it was swabbed, cultured, and the wound classified significance between the two groups on any day. The according to the resultant culture. mean bursting pressure rose sharply between the All wounds were inspected at follow-up 6 weeks third and seventh post-operative days and then after operation. Any wound discharging pus after levelled out. 124 0. J. A.