This study evaluated diaphragm thickness (DT) measured by ultrasound as a predictor of successful weaning from mechanical ventilation, compared to the rapid shallow breathing index (RSBI). 78 COPD patients undergoing ventilation were assessed with ultrasound during a spontaneous breathing trial to measure DT changes. A DT over 40% was highly accurate in predicting successful weaning, with sensitivity of 88% and specificity of 92%. RSBI under 105 was also found to be highly accurate in predicting success. The study concluded that DT assessed by ultrasound is an excellent predictor of weaning outcome in COPD patients.

1. 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

3. • 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

4. • 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), and a combined index named
CROP (compliance, rate, O2, pressure index) have
been used in common clinical practice

5. • Among the numerous parameters used
in clinical practice, the rapid shallow
breathing index is one of the most
accurate.

7. Objective
• The diaphragm thickening (DT)
measured by ultrasound was
evaluated as a weaning predictor
compared with the rapid shallow
breathing index.

9. • A prospective study included 78
patients with COPD exacerbation.
• All patients were ventilated in pressure
support through endotracheal tube.
• Both diaphragms were assessed by
chest ultrasound and those with
unilateral dusfunction were excluded
from study

10. • During spontaneous breathing trial
(SBT), the right diaphragm was
visualized in the zone of apposition
using a 7.5 MHz linear ultrasound
probe.

11. • The equipment used were ultrasound
apparatus (ALOKA – Prosound – SSD –
3500SV)

12. 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 peritonealmembranes at all
times while imaging the diaphragm
for thickness measurements.
• Zone of apposition

14. • DT was calculated as percentage
from the following formula:
T end-inspiration − T end-expiration
T end-expiration
• It was recorded at total lung
capacity (TLC) and residual volume
(RV).

15. • 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.

17. • A significant difference between
diaphragm thickness at TLC and RV
was observed both in patients who
succeeded SBT and patients who
failed.

18. • DT was significantly different between
patients who failed and patients who
succeeded SBT.
• A cutoff value of a DT >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%.

19. • 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.

20. Accuracy of US and RSBI in
prediction of successful
weaning:

22. • DT assessed by ultrasound is an
excellent predictor of weaning
outcome in COPD patients
undergoing mechanical ventilation.