The relation of age, gender and body mass index to the distance between the skin and the pleura on the second intercostal space

Tension pneumothorax is a life-threatening emergency. Needle decompression is the most common treatment method of choice. It has been done traditionally through the second intercostal space at mid-clavicular line. Success of this method depends on the length of the catheter and access to the pleura. Goal of this study is to determine the proper catheter length in patients with different body mass index by comparing the distance between the skin and the pleura on the second intercostal space at midclavicular line measured with computed tomography. We also aimed to find the accuracy of ultrasonographic measurement compared with computed tomography. We enrolled 150 adult patients who had thorax CT in Akdeniz University. Patients who are <18 years old and pregnant were excluded from the study. CT was accepted as the gold standard for the measurement of the distance between the skin and the pleura and we measured the distance between skin and pleura bilaterally at midclavicular lines and 8 cm from midsternal line and its intersection at the second intercostal space. Among all the patients enrolled, 58% was male (n=87), 42% was female (n=63). Mean age was 56,23±16. Sixty-four percent of the patients were young adults, 35.3% were consisted of older patients. Mean distance between skin and pleura on left side in all patients were found 36.2±1.34 mm; and 37.7 mm and 33.3 mm in females and in males respectively. Mean distance between skin and pleura on right side was found 36.19±1.31 mm; 43.1 mm in females and 31.2 mm in males. Taking into consideration that a standard catheter length is 5 cm and according to our measurements, in 22 patients (14.6%) in right-sided attempts and in 23 patients (15%) in left-sided attempts will not be able to reach pleural space, meaning that the procedure will fail. Even there is no statistical difference; we found that in obese patients, according to BMI, the skinpleura distance was longer. We concluded that approximately in 15% of the patients the needle decompression treatment at the second intercostal space in 45 midclavicular line will fail as the catheter length will not suffice. According to these findings we could estimate that the failure rate in obese patients would be higher. The correlation between US and CT was poor. The pressure on the skin during probing and breast tissue, muscle tissue or patient agitation may all effect this measurement. Therefore bedside US may not be a reliable tool to determine the distance between skin and pleura.