Basic Sonography
Ultrasound can enhance the diagnosis of organ injury, viable tumor, and vascular pathologies at bedside.
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Video 1. In-plane approach
The needle enters the skin at the short side of the transducer and the probe is slid toward the needle until seen
The transducer is readjusted frequently
Advantages
Disadvantages
Providers should choose the appropriate needle gauge, length and type
Larger gauge needles are easier to locate with ultrasound and should be considered for beginners
Several needles are available to perform nerve blocks:
Cutting point needles
Spinal needle (quincke tip)
Short-beveled or blunt-point needles
Figure 1. Needle Orientations
2 needle orientations for ultrasound guided procedures, the in-plane and out-of-plane approach
In-plane (long-axis) approach
Video 1. In-plane approach
The needle enters the skin at the short side of the transducer and the probe is slid toward the needle until seen
The transducer is readjusted frequently
Advantages
Disadvantages
Out-of-plane (short-axis) approach
Video 2. Out-of-plane approach
The needle enters the skin at the long side of the transducer and the probe is slid towards the needle until seen
The needle tip and shaft can look the same on ultrasound
The procedure involves allowing the needle to catch up to the ultrasound beam but never pass it:
This process is repeated down to the target
This catch-up motion prevents the needle tip from being lost or passing beyond the beam to damage deeper structures
Video 1. Out-of-plane approach
The needle enters the skin at the long side of the transducer and the probe is slid towards the needle until seen
The needle tip and shaft can look the same on ultrasound
The procedure involves allowing the needle to catch up to the ultrasound beam but never pass it:
Advantages
Disadvantages
During the block, keeping the tip in view is of critical importance. Doing so will result in the highest quality block and avoid the most devastating complications.
A few factors play into how well the tip displays:
Never advance the needle if you are unsure of the tip position.
Ensure to inject all air from needles as air in the tissue will prevent visualization of deeper structures.
Video 1. Anisotropy
Nerves can exhibit strong anisotropy