Ultrasound Guidance for Regional Anesthesia Procedures

Ultrasound Guidance for Regional Anesthesia Procedures

Ultrasound (US) guidance is an important tool for needle-based procedures in anaesthetic practice such as central venous cannulation and peripheral nerve blockade.ultrasound anesthesia needle It improves safety, success and block quality 1-5. However, failures and complications during vascular access procedures can lead to serious morbidity and local anesthetics can be inadvertently administered into the airway and cause systemic toxicity. In addition, incorrect identification of the needle tip on the ultrasound screen may lead to unintentional damage to structures not visualized. Therefore, many techniques have been developed to aid the alignment of needle and probe or needle identification on the US screen.

The most common error during UGRA is failing to maintain needle visualization during advancement.ultrasound anesthesia needle This results in inappropriate needle and probe maneuvers, which are often based on surrogate indicators. For example, the insertion of quiescent fluid serves as reverse contrast to the needle, and needle tip identification is more straightforward after injection of a small volume of clear solution 6.

Other strategies to improve needle visibility include the use of a smaller gauge needle and steeper angle of insertion 7.ultrasound anesthesia needle The ultrasound machine provides a real time display of the trajectory of the needle as it passes through tissue. This can help an operator anticipate the need to veer away from arteries or veins. However, the trajectory is based on the assumption that the needle is inserted parallel to the probe. In reality, the needle is inserted at a slight obtuse angle relative to the probe. The resulting reverberation of sound waves within the needle core appears as several 'copies' of the needle on the ultrasound image.

A simple technique to facilitate needle visualization is to place a piece of sterile pork rasher on the abdomen.ultrasound anesthesia needle A layer of colored ultrasound gel about 2.5 cm thick is applied over the rasher. Regional anesthesia needles are then passed perpendicularly through the gel and tissue into a depth of about 3 cm. The needles are then wiped with a sterile piece of gauze. The needles can then be easily identified without magnification on the ultrasound screen with adequate room lighting.

A recent study of novice behavior during 1-month regional anesthesia rotations demonstrated that a major error is not maintaining needle visualization during advancement.ultrasound anesthesia needle This can be overcome by placing the transducer against the patient or the bed and bracing the hand holding the probe against one of these surfaces. In addition, the scanning arm should be rested on a stable surface to minimize fatigue. By following these simple steps, UGRA can be performed safely and with confidence. This scoping review was made possible by a grant from the British Society for Regional Anesthesia.

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