Acta Anaesthesiol &and 1984: 28: 199-200

Infection Risks from Cannulae Used to Maintain Intravenous Access S. SALOHEIMO, C. HENNINC and U. HILLBORCH Intensive Care Unit, Department of Clinical Bacteriology and Department of Hospital Infection, Sundsvall Hospital, Sundsvall, Sweden

In an experimental in vitro study, it was shown that the rate of infection through the injection route was higher with VenflonB cannulae than with Intrafluxa cannulae (P<O.OI). A restricted use ofcannulae with injection side ports is recommended.

Received 27 May, accepted for publication 30 September 1983

Key words: Cannulae, venflon; infection; intravenous.

Intravenous infusion of fluid replacements and drugs is a crucial part of intensive care medicine. Contamination of the intravenous system is common and may result in septicemia. In a review (1) rates of septicemia varied from 0 to 8% and from 0 to 27% in cases with complete parenteral nutrition.

In patients in whom indwelling central venous cannulae and catheters have to be left unchanged for several days or weeks, the fibrin sleeve around the catheter tip is easily contaminated (2). Cannulae with a sideport have been criticized as increasing the risk of infection (3-5), in comparison of cannulae where the injection port is self-sealing and easily disinfected. In other studies it has been claimed that the infection rate with open sideport cannulae is not higher than for cannulae without sideports (6-8).

The aim of this study was to compare the infection rate by injections given through a cannula with a sideport to those given through a cannula with a self- sealing injection port, using a laboratory model.

MATERIAL AND METHODS Venflona cannulae (Viggo A B, Helsingborg, Sweden) with an integral, internal silicone-valved sideport or IntrafluxB (Vygon S. A,, Ecouen, France) with a self-sealing rubber membrane injection site which can be disinfected (Fig. 1) were both aseptically attached to a series of 32 locally produced biphasic blood-culture bottles.

Sterility was checked after attachment by incubating all sets for 4 days at 37OC. The 64 sets were numbered at random (9) and placed in order in eight rows on a tray. During the whole experiment the tray was left exposed to airborne bacteria during working hours in the crowded unpacking room in the bacteriology laboratory, and in- cubated at 37°C overnight.

Two sets in each series served as controls. To the other 60 bottles, 0.1 ml sterile physiological saline was injected (syringe 0.6X25 mm) five times daily for 40 working days. Injections were started each day with a

bottle chosen at random and the other sets were completed consecu- tively. The Intraflux sets were disinfected with 70% ethyl alcohol before injection. The Venflon sets were injected directly into the sideport without disinfection after the protecting lid had been lifted. The lid was replaced immediately after each injection. All injections were given by one of us (U.H.) or one single technician. The controls were not injected but were otherwise lifted and handled as above. Sets with visible growth were withdrawn, and the contaminating bacteria were subcultured on suitable media and grouped.

Satistics The proportions of infected bottles in each group were compared using Fischer's exact probability test (10). The level ofsignificance used was P< 0.05.

RESULTS In the Intraflux series, no growth was detected (0/30). In the Venflon series, eight sets were infected (8/30)

The bacterial growths in the Venflon sets were randomly distributed over the whole time of the experi- ment and were found after injection day 10, 13, 19, 20, 21, 21, 22, and 40. The corresponding numbers of injections were 45, 60, 90, 95, 100, 100, 105, and 195. The bacterial growth rate per injection was 0.15% (8/5230). The contaminations were distributed at ran- dom and did not increase in frequency with increasing number of injections. The contaminants were found in pure culture in seven cases and as three different strains once. The bacteria comprised Staphylococcus epidermidis 4, alphahemolytic streptococci 2, diphtheroids 1, other gram-positive rods 1, and other gram-positive cocci 2, suggesting contamination with normal skin flora.

After the injections were stopped, the sets were incubated at 37°C for another 1 month without further growth.

(P<O.Ol).

200 S. SALOHE LIMO ET A1

B)

Fig. 1. Cross section of: A) valved injection sideport and B) rubber membrane injection site.

DISCUSSION Many different details contribute to the optimal goal of avoiding infections during treatment with indwelling catheters (1). It is often impossible to design controlled clinical trials where all factors but that under study are comparable and unchanged over the whole intervention period, especially when the studied phenomenon seldom occurs. When the aim is to compare only one detail performed with different techniques, pure laboratory experiments could be justified. The results ofthe present study prove that the infection rate with the Intraflux is statistically significantly lower than with the Venflon. The rate of infection found, however, could not be directly transferred to the clinical situation.

The situation is different from the clinical situation, where catheters and their surroundings are more heavily contaminated by both patient and staff, the injections are given by many different persons and the number of injections varies between patients. All these circum- stances increase the possibility of infection. Our pre- liminary results from 20 sets in an ongoing study run in a manner more similar to the clinical situation point to similar differences between the two types of cannulae and a tendency to an increased rate of infection.

From our results, we conclude that injection sideports should be avoided: - When high numbers of injections must be given; - When a central venous cathether is used for injections;

- When treating immunocompromised patients; and - In cases with an increased disposition to sepsis.

ACKNOWLEDGEMENT The statistical advice of BjGrn Jonsson, Statistical Department, Stockholm University, Stockholm, Sweden, is much appreciated.

REFERENCES 1. Maki D G, Goldman D A, RhamC F S. Infection control in

intravenous therapy. Ann intern Med 1973: 7 9 867-887. 2. Bailey M J. Reduction of catheter-associated sepsis in parenteral

nutrition using low-dose intravenous heparin. Br Med 3 1979: 1: 1671-1673.

3. Oberhammer E P. Contamination of injection ports o n in- travenous cannulae. Lancet 1980: i i 1027-1028.

4. Peters J L, Fisher C, Ridgway G L, Armstrong R F, Mehtar, S. Risks from cannulae used to maintain intravenous access. Br Med 3 1981: 282: 1549-1550.

5. Pilsworth R. Risks from cannulae used to maintain intravenous access. BY MedJ 1981: 282: 222-223.

6. Macfarlane J T, Ward M J, Banks D C, Pilkington R, Finch R G. Risks from cannulae used to maintain intravenous access. Br Med 3 1980: 281: 1395-1396.

7. Noble C J, Morgan-Capner P, Hammer M, Sivyer C, Wagstaff P, Pattison J R. A trial of povidone iodine dry powder spray for the prevention of infusion thrombophlebitis. 3 Hasp infect 1980 1: 47-51.

8. Cowan M E. Bacterial contamination of sideports of Venflon intravenous cannulae. .7 Hosp Infect 1982: 3: 73-79.

9. Armitage P. Statistical methods in medical research. Oxford: Blackwell Scientific Publications, 1971.

10. Diem K. Wissenschaftliche Tabellen, 6th edn. Basel: Geigy Pharmazeutische Abteilung, 1960.

Address: 5. Saloheimo, M.D. Intensive Care Unit Sundsvall Hospital S-851 86 Sundsvall Sweden