Medical student

Manipulating the probe

A terminology to describe the movement of the probe during scanning is important in order to optimise the image

During the workshop it makes it easier for the supervisor to give instructions without touching the probe which is crucial for the novice in order to achieve practical skill

There are many available descriptions of the method of manipulation of the probe

We recommend using:
1. rotation
2. tilt
3. slide

These movements are applicable to all scanning locations

As a novice – always, only move the probe in one direction at a time

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Figure showing movements in three different spatial directions
The icon at the bottom indicates that movement should only take place in one plane at the time

XX 9 – Instruction in manipulation of the probe

During the workshops the supervisors are encouraged to give instructions with reference to the tail of the transducer and a secondary reference point when appropriate

Examples of secondary reference points:
1. anatomical land marks in relation to the volunteer or patient
2. physical land marks like the bed
3. spatial: left/right – upwards/downwards – medial/lateral

When complying with an instruction, never do any movements in other directions

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Transducer manipulations with reference to the tail of the probe and four different secondary reference points: X, Y, Z ,V

XX 4 – The orientation marker on the transducer

The probe is fitted with an orientation marker (OM)

On the image the OM is indicated by a green arrow

The OM facilitates the correct orientation of the probe on the patient

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The OM (green arrow) has to be oriented in correct relationship with the corresponding orientation indicator (OI) on the monitor

Display of the sector on the screen

In FATE and adult cardiac ultrasound, the ultrasound image displays the sector with the two radii diverging from the top of the screen

The orientation indicator is on the right side of the screen, and the arch of the sector is displayed towards the bottom of the screen

The ultrasound image on the screen can be turned upside/down or left/right with user controls

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The video clip shows the ultrasound sector placed correctly and incorrectly. Remember that the right orientation is with the top of the sector pointing upwards, and the orientation indicator (OI) on the right side of the screen. (Please note, the video may be slow to load depending on your internet connection)

Why use ultrasound for peripheral vascular access?

The advantages of ultrasound guidance for vascular access

Peripheral veins
– Visualisation and use of vessels we cannot see otherwise – i.e. more vessels become available
– More accurate assessment of vein localisation and patency
– Real-time visualisation of needle placement with accurate needle control
– Higher success rate in difficult cases including children

Peripheral arteries
– More accurate assessment of artery localisation and patency
– Higher first time success rate
– Vascular puncture and catheter insertion in localisations not used with traditional blind technique
– Avoiding puncture of the deep side of an artery during needle insertion contrary to traditional blind technique

Vascular access: a basic skill for all healthcare professionals

Vascular access is often easy and straightforward. But from time to time it can be very difficult with multiple failed attempts

Point-of-care ultrasonography most often facilitates rapid and successful vascular access in difficult cases

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Multiple failed attempts – a common but unacceptable threat to the patients

Time Gain Compensation (TGC)

TGC is a user controlled selective amplification of signals reflected from particular depths in the tissue

TGC compensates for the depth-dependent attenuation of the ultrasound wave

A typical user control panel is illustrated in the image

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By fine tuning TGC, optimal image quality can be achieved at all depths of the image.
In the top image TGC is increased in the upper bands resulting in increased (more white) gain in the near field. In the bottom image TGC is increased in the lower bands. The middle image has appropriate TGC.

Summary

You are now familiar with the ultrasound system and the probe and how to optimize the ultrasound image

You are ready to start the lessons about the clinical application of ultrasound

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Depth: Keep all relevant details in the image

The depth of the displayed image can be adjusted using the depth controls

When the depth of the field-of-view is increased, it becomes possible to display deeper structures

When the depth is decreased, the field-of-view is narrowed around structures closer to the probe and deeper structures are omitted

Reduction of the depth means that the time from emitted to received signal is reduced; this allows a higher frame rate

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The image on the right shows an ultrasound image of the heart with different depth settings
The top image is too shallow, the depth of the middle image is appropriate, and the depth in the bottom image is too great

Acoustic coupling – the importance of ultrasound gel

It is very important to apply plenty of ultrasound gel to ensure maximum transmission of ultrasound into the tissue and facilitate the acoustic coupling between the probe and the patient

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The video shows two different ultrasound images of the same blood vessel at the wrist in the same patient, when a sufficient and an insufficient amount of ultrasound gel is used. At the top the probe is placed on a “dry” arm, and at the bottom plenty of gel has been used