Discussion:
Chest ultrasound in the diagnosis of Pneumothorax was reported first in
1986 in a veterinary journal. Several researchers have explored its
usage since then. The principal method for diagnosing employed an absent
sliding lung sign in the air presence between visceral and parietal
pleura.26 The presence of sliding lung signs acts as
an accurate negative predictor for pneumothorax detection. Dulchavsky et
al. 27 described a 100% true negative rate compared
to conventional chest radiographs in Pneumothorax diagnosis, with
sensitivity ranging from 90% to 100%.
Most of the studies used focused assessment with sonography for trauma
(FAST) technique for diagnosing pneumothorax. Literature has shown
accurate and fast results. Standard FAST protocols assess four locations
(pericardial, perihepatic, perisplenic, and pelvis). Still is more
feasible and simpler to widen the scanned regions to assess the chest
for haemothorax formally. 28,29
The present systematic review and meta-analysis showed a better
performance of chest ultrasound in detecting pneumothorax and can be
used as an alternative to CT and MRI.
Pneumothorax diagnosis can be made based on physical examination and
symptom presentation. Confirmation is generally via radiography or C.T.
scanning. Radiographs taken in the later stages pose difficulty in
diagnosing pneumothorax because of the patient’s condition, distance and
other considerations. Also, chest radiograph reliability is
questionable, and a wrong diagnosis may be expected in 30% of cases.23. The metanalytic study of Ebrahimi et
al29 showed ultrasound accuracy in detection of
pneumothorax, with sensitivity of 0.87 (95% CI: 0.81–0.92;I 2 = 88.89; P <0. 001)
and specificity of 0.99 (95% CI: 0.98–0.99;I 2 = 86.46, P <0. 001).
Our study results are also in similar lines with a sensitivity of 0.89
and specificity of 0.96.
The present study included both adult and neonate populations, and the
diagnostic accuracy was good. The results of Hamid Dahmarde et
al. 30 also support this statement. The sensitivity,
specificity, and odds ratio of the chest ultrasound in the diagnosis of
pneumothorax in neonates was 96.7% (88.3%–99.6%), 100%
(97.7%–100%), and 1343.1% (167.20–10788.9), respectively, depicting
superior results.
The study has certain limitations. Firstly, it should be borne in mind
that the test characteristics merely a part of evaluation of diagnostic
test function, and extent of each test depends on its effect on patient.
The second factor which can affect the course of meta-analysis is the
chest ultrasound operator’s accuracy. The training quality and nature of
training are not considered in several studies. The heterogeneity of
studies included was also higher; thus, the random-effects model was
employed to obtain better results.