Improvised glove barrier for ultrasound probe protection.

Sir,

The use of ultrasound in anesthesia and intensive care has evolved through its inception to an unavoidable entity in modern day practice. Evidence corroborating its use is accumulating day by day. Compliance to sterility and strict aseptic precautions as in any invasive procedure need to be maintained while using ultrasound as there have been reports of bacterial infections transmitted through ultrasound probe and coupling gel, even though outside the perioperative setting.[1]

Multiple methods of probe disinfection like cleaning the probe with sterile paper, use of alcohol-based solutions, and use of ultraviolet-C light have been described.[2] The use of repeated alcohol disinfection decreases the brightness of the image with linear array ultrasound probes.[3] Moreover, the cost constraint scenario like ours preclude the use of commercially available ultrasound probe covers for every procedure. In their absence; sterile gloves, transparent dressings, and boot covers have been used as an alternative, the most familiar being sterile gloves. These alternatives do not provide a sterile field from probe tip throughout the cord, however, a clean probe surface is guaranteed. These “probe only” protective barriers prevent any direct contact between the ultrasound probe and punctured skin, in effect converting the probe from a “semicritical” to a “noncritical” device, as per the level of decontamination recommended for medical devices.[4] Alakkad et al. reported nil block related infection in a retrospective analysis of 7476 patients who received ultrasound-guided single-injection peripheral nerve blockade in a center using low-level disinfection technique in combination “probe only” barrier with sterile transparent film to cover the ultrasound transducer.[5]

The use of sterile gloves as probe cover requires multiple maneuvers to fasten the fingers of the glove just above the probe, which invariably leads to accumulation of air pockets within, obscuring the image. We have been using a modified technique with sterile gloves in our center. Here, the block-provider separates finger portion of the sterile glove using sterile surgical blade [Figure 1]. After applying the coupling gel, the assistant holds the probe upright as the block-provider stretches the finger portion of the gloves and covers it over the probe. This modified probe cover fits in snugly around the probe avoiding any further fastening manures [Figure 2]. Small air pocket that may rarely ensue after this can successfully be emptied with a small nick with a sterile needle, neither affecting the image quality nor causing a tear in this modified probe cover. The method is cost friendly compared to the use commercial transparent dressings. Moreover, 10 separate modified probe covers of this sort can be generated from a single sterile pair of gloves.

Figure 1

Finger portion of sterile gloves separated

Figure 2

Finger portion of glove snugly covering the ultrasound transducer

The limitations of this technique are self-evident. This method cannot be used for ultrasound-guided vascular access where catheter-associated blood stream infection is a concern. This method does not ensure strict asepsis however; it effectively replaces the transparent dressing “probe only” barrier used in many centers, and in a way converts the ultrasound probe to a “noncritical” medical device. We recommend this novel inexpensive method of “probe only” protection, for single injection ultrasound-guided peripheral nerve blockade. Further studies with large sample population are required to prove its efficacy.