Role of Sonography in

RICU

Gamal Rabie Agmy, MD, FCCP Professor of chest Diseases, Assiut University

High Frequency

• High frequency (5-10 MHz)

greater resolution

less penetration

• Shallow structures

Low Frequency

• Low frequency (2-3.5 MHz)

greater penetration

less resolution

• Deep structures

Probes

A common language: Color Coding

Black Grey White

http://radiographics.rsnajnls.org/content/vol22/issue1/images/large/g02jae1g2a.jpeg

Diaphragm Ultrasound as a

Novel Guide of Weaning from

Invasive Ventilation

Gamal Agmy , MD , FCCP Professor of Chest Diseases and respiratory ICU,

Assiut University, Assiut , Egypt

I have no Conflict of Interest

• Difficulties in weaning from

mechanical ventilation are

encountered in approximately 20%

of patients, and more than 40% of

the time passed in the intensive

care unit is spent to try to wean off

from mechanical ventilation

• Several indexes have been employed to assess the patient's ability to recover spontaneous breathing.

• Variables such as minute ventilation (Ve), maximum

inspiratory pressure (PImax), breathing frequency, rapid shallow breathing index (RSBI, i.e., respiratory

frequency/tidal volume), tracheal airway occlusion

pressure 0.1 s (P 0.1), P0.1/ PImax >0.3, P0.1Xf/VT<300 , a combined index named CROP

(compliance, rate, O2, pressure index) >13, IWI>25 and CORE >8 have been used in common clinical

practice

• Among the numerous parameters used

in clinical practice, the rapid shallow

breathing index is one of the most

accurate.

Objective

• The diaphragm thickeness

Fraction (DTF) measured by

ultrasound was evaluated as a

weaning predictor compared

with the rapid shallow breathing

index.

• A prospective study included 78 patients

with COPD exacerbation.

• All patients were ventilated in pressure

support through endotracheal tube.

• During spontaneous breathing trial (SBT),

the right diaphragm was visualized in the

zone of apposition using a 7.5 MHz linear

ultrasound probe.

• The equipment used were ultrasound

apparatus (ALOKA – Prosound – SSD –

3500SV)

Diaphragm Thickness (DT)

• High frequency transducer 7.5

MHz

• Anterior axillary line

• Sagittal image at the intercostal

space between the 7th/8th , 8th /9th

ribs

• Visualization of both the pleural

and peritoneal membranes at all

times while imaging the diaphragm

for thickness measurements.

• Zone of apposition

DTF was calculated as percentage

from the following formula:

T end-inspiration − T end-expiration

T end-expiration

DTF was measured during deep

inspiration and forced expiration

• The rapid shallow breathing index

(RSBI) was calculated.

• Weaning failure was defined as the

inability to maintain spontaneous

breathing for at least 48 h, without

any form of ventilatory support.

• A significant difference between

DTF at deep inspiration and forced

expiration was observed both in

patients who succeeded SBT and

patients who failed.

• DTF was significantly different between

patients who failed and patients who

succeeded SBT.

• A cutoff value of a DTF >40% was

associated with a successful SBT with a

sensitivity of 88%, a specificity of 92%, a

positive predictive value (PPV) of 95%, and

a negative predictive value (NPV) of 82%.

• On the other hand , RSBI <105 had

a sensitivity of 95%, a specificity of

90%, a PPV of 96%, and a NPV of

92% for determining SBT success.

Accuracy of US and RSBI in

prediction of successful

weaning:

• DTF assessed by ultrasound is an

excellent predictor of weaning

outcome in COPD patients

undergoing mechanical ventilation.