[Ultrasound guided regional anaesthesia: an effective method for cleaning the probes]

The objective of this study was to determine if the ultrasound probe can act as a vector for cross-infection and to compare two cleaning methods for ultrasound probes in order to limit or control the transmission risk.

Prospective study.

The first part of the study (P1) was conducted to evaluate the possibility of the ultrasound probe to serve as a source of cross-contamination. Thirty blocks were placed under ultrasound guidance in elective outpatients. After each procedure (Proc), the ultrasound probe was decontaminated/cleaned using either an antiseptic solution spray (AS: n=15) or just wiped with two dry paper sheets (DP: n=15), in a randomly assigned order. Bacteriological samples were collected before and after each decontamination/cleaning methods and inoculated on a chocolate agar plates. The second part of the study (P2) was conducted to compare the effectiveness of two cleaning methods for ultrasound probes. The ultrasound probes were exposed to a large inoculum of three bacteria (Inoc). They were then cleaned/decontaminated using either DP (n=10) or AS (n=10), in a randomly assigned order. Bacteriological samples were collected before and after each cleaning/decontamination methods and inoculated on a chocolate agar plates.

During P1, after Pro, all probes were found to be sterile before and after both AS and DP. During P2, after Inoc, all probes were found infected (CFU>150) but were considered sterile (CFU<10) after both DP and AS.

The results of this study suggest that the risk of cross-infection during ultrasound guidance in locoregional anaesthesia is really low. Our data suggest that wiping ultrasound probe with two dry paper sheets is an adequate cleaning method to prevent cross-contamination risk.