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By Dr. Kenechukwu Madu , Dr. Obinna V Ajuzieogu , Dr. Ezike Humphrey A. , Dr. Amucheazi Adaobi O
Corresponding Author Dr. Obinna V Ajuzieogu
Anaesthesia Department, University of Nigeria, Enugu Campus, - Nigeria
Submitting Author Dr. Obinna V Ajuzieogu
Other Authors Dr. Kenechukwu Madu
Trauma Department, National Orthopaedic Hospital, - Nigeria

Dr. Ezike Humphrey A.
Anaesthesia Department, University of Nigeria Teaching Hospital, - Nigeria

Dr. Amucheazi Adaobi O
Anaesthesia Department, University of Nigeria Teaching Hospital, - Nigeria

ANAESTHESIA

Infection, Theatre population, Implant surgery

Madu K, Ajuzieogu OV, Humphrey A. E, Adaobi O A. Relationship between Theatre Population and Post Operative wound Infection Following Implant Surgeries. WebmedCentral ANAESTHESIA 2011;2(10):WMC002359
doi: 10.9754/journal.wmc.2011.002359
No
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Submitted on: 25 Oct 2011 07:53:07 AM GMT
Published on: 25 Oct 2011 03:44:15 PM GMT

Abstract


Infection occurring after internal fixation of a fracture is a devastating complication and may be difficult to treat. This was a prospective study to assess the relationship between theatre population and postoperative wound infection (POWI). The theatre population was determined by counting the number of people in the theatre for the duration of the surgery. Wound surveillance was carried out for the patients over a 6-month period postoperatively. The data obtained was analysed using SPSS and PRISM 5 software. Only 9 (9.3%) cases in theatres with more than six persons had POWI.  This was not statistically significant. (P=1.0, OR 1.23) We conclude that theatre population up to 6 does not contribute significantly to POWI.

Introduction


Post operative wound infection (POWI) following implant surgery, though relatively uncommon, constitutes a serious problem in surgical practice.
Reported infection rates vary amongst centres. The reported incidence of infection after orthopaedic operations on a broad cross section of patients varies from 0.2 to over 10%.
The main objective of this study was to determine the incidence of post operative wound infection in implant surgery, to assess the relationship between theatre population and the development of POWI.

Methods


Approval for this one year prospective study was obtained from the ethical committee of the National Orthopaedic Hospital, Enugu and informed consent was obtained from the patients. The Hospital is a regional center for management of orthopaedic, trauma, plastic and reconstructive surgery cases. The study included all patients who had implant surgery between the 1st of February and the 31st of July 2007. The patients were followed up for 6 months.
PATIENT SELECTION
Sample size: The sample size was determined using the formula n=z?2pq/d2

Where z? =standard deviation at 95%,
p=6.4%
q=1-p
d=standard error (5%).
The minimum sample size was 90. Ninety seven (97) patients were then recruited for the study within the first 6 months and followed on an out-patient basis for the next 6 months
Inclusion criteria were all patients presenting in the hospital from the 1st of February 2007 to 31st of July 2007 with closed fractures of bones treated by open reduction and internal fixation using implants and had no pre-existing or co-existing immunocompromising disease. Patients were excluded if they had previous surgery at the fracture site, because of the possibility of a latent infection or were not willing to participate in the study. The selected patients had proforma opened for them. The authors inspected all the surgical wounds. All patients received antibiotic prophylaxis with intravenous ciprofloxacin. The antibiotic sensitivity disc pattern determined which antibiotic was used for treatment where wound infection occurred. Strict asepsis was maintained.
The theatre population was determined by counting the number of people in the theatre for the duration of the surgery. This included the surgeons, anesthetists, scrub nurses and their various assistants.
Patients had their wounds inspected 72 hours post operatively and alternate daily if signs of infection were seen. Healed wounds were followed up in clinic for the duration of the study. Wound swabs or aspirates were taken from all discharges for microscopy, culture and sensitivity to antibiotics. 
The diagnosis of wound infection was made based on the presence of pus in a wound which had either spontaneously discharged or had to be removed by the removal of sutures or reopening of the incision as recommended by the National Research Council.

Results


Within the study period, 97 patients met the inclusion criteria for the study. Sixty one (63%) of the patients were males, while 36 (37%) were females (Fig 1). The male to female ratio was 1.7: 1. Wound infection occurred in 6 (6.2%) males while 3 (3.1%) females developed wound infection. The difference in infection between sexes was not statistically significant (P=0.805). The age range was 7 to 83years. The mean age was 38.7yrs (fig 2). Two (2.1%) of the infected cases were seen in the twenty four patients aged 1-25 years (table 1). Four (4.1%) of the infected cases were seen in the fifty one patients aged 26-50 years, while 3 (3.1%) infected cases were seen in the seventeen patients aged 51-75 years. No infection was seen in the five patients aged 76-100 years. The difference was not statistically significant (p>0.05). All the infected cases {9 (9.3%)} had a theatre population of more than six persons (table 2). None of the cases done had less than 4 persons in the theatre. Three (3.1%) cases were done with 4 – 6 people in theatre and no infection was seen in these groups. The Fisher exact test was used to analyse the relationship between POWI and theatre population. There was no significant contribution from theatre population (P=1, OR 1.23, 95% CI).

Discussion & Conclusion


Postoperative wound infection following implant surgery, though relatively uncommon constitutes a serious problem when it occurs. Postoperative wound infection after internal fixation of a fracture is a devastating complication and may be extraordinarily difficult to treat 1,4,5,6

Various hospitals in Nigeria have reported varying rates of postoperative wound infection following implant surgery. In this study, the infection rate was found to be 9.3%. This figure compares favorably with  an earlier result of 15% obtained by Nwankwo et al 7 studying postoperative wound infection after Austin-Moore hemiarthroplasty in this same institution. An earlier study by Onche 3 at the National Orthopaedic Hospital, Igbobi, Lagos State recorded a postoperative wound infection rate of 6.4% following implant surgery. This was lower than the infection rate of 9.3% found in this study. In this study, the theatre population during the procedure was found to be significantly associated with occurrence of postoperative wound infection following implant surgery. Other risk factors which were found to be contributory to development of postoperative infection in other studies including age and sex, were found not to be contributory in this study.

Onche in Lagos found that age was not a significant risk factor. 3 Cruse and Foord 8, on the contrary, reported that patients aged over 66 years were six times more likely to develop wound infection than those aged one to fourteen years while Cronquist et al 9 reported that younger people were at a higher risk of developing surgical site infection.

The sex of the patient was not found to be significantly associated with the risk of developing postoperative wound infection in this study. This is contrary to reports by Moylan and Kennedy 10, who found that sex, influenced the incidence of wound infection with the female sex having a higher wound infection rate.

Ninety seven percent (96.9%) of cases in this study were done with a population of more than 6 persons in the theatre but only nine (9.3%) developed POWI. This is similar to the report by Onche 3 in Lagos who found that theatre population did not significantly affect the risk of developing post operative wound infection, although most cases in his series had less than 6 people in theatre.

In conclusion, we found that increased theatre population does not significantly lead to more postoperative infection. Patient age and sex also have no influence on the occurrence of postoperative infection.

References


1. Schmidt AH, Swiontkowski MF. Pathophysiology of infections after internal fixation of fractures Am Acad Orthop Surg 2000; 8:285 -291.
2. Solomon L, Warwick D, Selvadurai N. Infection. In Solomon L et al. Ed. Apley’s System of Orthopaedics and Fractures.8th edition. New York, Arnold 2001.Chapter2, page35. 3. Onche II. Postoperative wound infection in implant surgery. Dissertation submitted to the National Postgraduate Medical College of Nigeria, may 2000.
4. Garvin KL, Mormino MA, Mckillip TM. Management of infected implants. In: William Chapman.Ed.Chapman’s orthopaedic surgery. 3rd edition.Philidelphia, Lippincott Williams & Wilkins 2001. Section seven, chapter 135
5. H.Willenegger et al. Infections. In: Allgower M.Ed. Manual of internal fixation.3rd edition.Berlin, Springer-Verlag 1992. Chapter 20:3 page 744.
6. Wood GW II. General principles of fracture treatment. In Canale TS. Ed. Campbell’s operative orthopaedics.10th edition. Mosby Inc 1999.Vol 3 chapter 50, page 2714.
7. Nwankwo OE, Eze CB, Onabowale BO, Osisioma ECO. Infection rate using Austin Moore prosthesis for partial replacement arthroplasty of the hip in an ordinary operating theatre: 11 year experience at National Orthopaedic Hospital, Enugu. Orient journal of medicine 1990; vol. 2, no 2:66-69.
8. Cruse PJE, Foord R. The epidemiology of wound infection; A ten year prospective study of 62,939 wounds. Surg. Clin. North Amer. (Symposium on surgical infection) 1980, 60(1): 20-40.
9. Cronquist AB, Jakob K, Lai L, Della Latta P, Larson EL. Relationship between skin microbial counts and surgical site infection after neurosurgery. Clin Infect Dis 2001; 33: 303-308.
10. Moylan AS, Kennedy VB. The importance of gown and drape barriers in the prevention of wound infection. Surg. Gyn Obst, 1980; 151: 465-470.

Source(s) of Funding


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Competing Interests


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ERRATUM Posted by Dr. Obinna V Ajuzieogu on 09 Mar 2013 01:27:59 PM GMT

 

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