Role of ultrasound in ICU

Ashraf Nasief, MD.

Ultrasound in the field of critical care

• The use of ultrasound has expanded enormously over the last two decades in critical care research and practice. Despite the fact that the method is operator dependent . It has many advantages, it enables clinicians for rapid, by-the-bed, relatively inexpensive, can be repeated, and save diagnostic evaluation of unstable patients.

Types of probes

B-mode VS m-mode• B-mode or 2D mode (brightness mode): a linear array

of transducers simultaneously scans a plane through the body that can be viewed as a two-dimensional image on screen.

• M-mode (motion mode): pulses are emitted in quick succession – each time B-mode image is taken. Over time, this is analogous to recording a video in ultrasound. As the organ boundaries that produce reflections move relative to the probe, this can be used to determine the velocity of specific organ structures.

Examples 0f use of US in ICU

• 1- Assessment of volume status

• 2- US of the lung

• 2- Diagnosis of pneonumothorax, hemothorax and pleural effusion.

• 3- Vascular access

• 4- proper endotracheal intubation

• 5 – prediction of post-extubation stridor

• 6- Assessment of the diaphragm.

• 7 differential diagnosis of shock

Assessment of volume status

• The 2008 ACEP Policy Statement on Emergency Ultrasound Guidelines includes the evaluation of intravascular volume status and estimation of central venous pressure (CVP) based on sonographic examination of the inferior vena cava (IVC).

• ACEP Policy Statement on Emergency Ultrasound Guidelines. Ann.

Emerg. Med. 2009;53:550-70.

Can US give us a rapid answer to this question

Does this patient need fluid??

How to examine?

Cross section appearance

Normal IVC

Total collapse of IVC

Using the M-mode

Normal M-mode

Caval index

• IVC expiratory diameter - IVC inspiratory diameter

/IVC expiratory diameter × 100 = caval index (%).

• 0%________________________________ 100%

Volume Volume

overload depletion

The aorta in a 8 yrs child

Caval /aorta index

Different valuesMeasuring the IVC/Ao irrespective to the

respiratory cycle has made the study simpler and patient specific, and does not necessitate looking at reference values for each age group. The mean

IVC/Ao in patients euvolemic is 1.2 ± 0.12 SD, hypovolemic is 0.7 ± 0.09 SD, and volume overloaded is 1.6 ± 0.05 SD, respectively.

Pneumo and hemothrax

Ouellet J-F et al., The sonographic diagnosis of pneumothorax. JEmerg Trauma Shock. 2011

Stone MB et al., The heart point sign: description of a new ultrasound finding suggesting pneumothorax.Acad Emerg Med. 2010

seahore- sign

stratosphere- sign

M- mode, sliding lung sign

comet- trail- artifacts

reverberations

B- mode

How to examine

Ultrasound areas.

Normal lung

Normal lung

pneumothorax

Seashore apperance

M-mode in normal and pneumothoraxSeashore Stratosphere

How to examine

Hemothorax

Rt pleural effusion

RT pleural effusion

Lt pleural effusion

The problem of pediatrics

• There are no established age-wise norms for diaphragmatic excursions. Diaphragmatic excursion less than 4 mm, paradoxical movement, and difference of more than 50% between excursions of the hemidiaphragms at M-mode US are diagnostic of unilateral paralysis.

Diaphragmatic paralysis in a 7-month-old child

An advice of 2 steps1- When I was a child

I talked like a child

I thought like a child

I reasoned like a child

When I became a man

I put childish ways behind me

2- Now I see but a poor reflection . Then I shall see face to face

Now I know in part

Then I shall know fully.

Summary• Ultrasound is a very useful tool in the field of

ICU and critical care medicine.

• Ultrasound machine should be available in every ICU and emergency department.

• We should encourage ICU and critical care physicians for the use of US by adequate training.

Thank you