(1040) Optimizing Anatomic Site Selection for Needle Decompression and Chest Tube Placement for Pneumothorax in Pregnancy

Objective:
Tension pneumothorax can cause life-threatening respiratory and cardiac complications. Prompt decompression is essential, with current guidelines favoring the 4th or 5th intercostal space (ICS) at the anterior axillary line (AAL) over the traditional 2nd ICS at the midclavicular line (MCL).  In pregnancy, physiologic changes such as diaphragm elevation and altered thoracic anatomy may influence the safety and effectiveness of these sites.  The primary objective of this study is to determine the optimal location for needle decompression and chest tube placement in pregnancy utilizing chest x-ray (CXR) and computed tomography (CT) imaging.

Study Design:
Imaging from pregnant patients with singleton pregnancies between 6-41 weeks were retrospectively analyzed. CXRs were used to measure diaphragm position relative to the anterior ribs and ICS at the MCL. CT scans were used to assess diaphragm position at the AAL, chest wall thickness (CWT), and distance to vital structures (DVS) at the 2nd ICS (MCL) and the 4th and 5th ICS (AAL).  ANOVA was used to assess differences across sites and trimesters.

Results:
A total of 91 CXRs and 56 CT scans were analyzed.  The diaphragm was located between the 4th-8th ribs at the MCL and the 5th-8th ribs at the AAL, with no statistical difference when stratifying by trimester (Table 1).  Mean CWT was greatest at the 2nd ICS (MCL) and thinnest at the 5th ICS (AAL) with a statistically significant difference across sites (p< 0.001).  The shortest mean DVS was at the left 5th ICS (AAL) (Table 2).  On the right, the liver was in the needle path in 31% of cases at the 5th ICS, while at the 4th ICS both abdominal structures and the diaphragm were not encountered.

Conclusion:
Needle decompression site in pregnancy requires balancing safety and procedural success. The 2nd ICS (MCL) offers the greatest DVS but may fail due to increased CWT. The 4th and 5th ICS (AAL) offer thinner chest walls but pose greater risk of organ injury, particularly on the left.  Due to the thinner chest wall and lack of abdominal structures, the 4th ICS (AAL) may be the optimal decompression site in pregnancy.