Journal: Anesth Analg 105(5):1385-1388, 2007. 13 References
Reprint: Dept of Anesthesiology, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, Box 1010, New York City, NY 10029 (D Wax, MD)
Faculty Disclosure: Abstracted by L. Easley, who has nothing to disclose.
The recommended treatment of suspected tension pneumothorax is immediate needle decompression followed by chest tube thoracostomy. As an alternative to the long-standing practice of using the second intercostal space at the midclavicular line, needle decompression in the fourth or fifth intercostal spaces at the mid- or anterior axillary lines (MAL, AAL) has been proposed. The authors performed this radiological investigation to determine the optimal needle length and relative safety of each potential decompression site.
Thoracic computed tomography (CT) scans of 100 adult patients in the authors’ hospital’s radiology archive were reviewed. The scans were selected randomly from a list of patients who had undergone anesthesia for video-assisted thoracoscopy in the prior 12 months, and were therefore likely to have an archived chest CT scan. Using soft-tissue windowing and the electronic calipers of the PACS workstation, distances between various anatomic sites were measured. The median distances from the midline of the sternum at the level of the sternal angle to the midhemithoracic line (MHL) and internal mammary vessels were 6.1 and 3.0 cm, respectively, with a 3.1 cm median gap between the two. Median depth-to-pleura below the skin surface at the MHL, MAL, and AAL sites was 3.1, 3.5, and 2.6 cm, respectively.
There was a larger proportion of subjects with major soft-tissue structures within both 5 and 10 cm of the needle entry site and directly adjacent to the chest wall for bilateral MAL and AAL sites compared with the ipsilateral MHL site. Overall, there was less safe distance on the left side compared with the right side, and the safe distance was greatest for the MHL site and least for the AAL site on either side.
These data suggest that a needle length of 7 cm would be adequate for nearly all patients at the MHL site, but may be too short for the axillary sites in some patients. Increasing weight and BMI both correlated with increasing depth-to-pleura at all sites. Regarding needle siting, literature from anesthesiology and other specialties suggests a variety of sites and needle sizes for decompression of tension pneumothorax. Locating the appropriate level for needle insertion using easily palpated bony surface landmarks may increase consistency and save time in a crisis, compared with counting intercostal spaces. The proper MHL site may be quickly determined by inserting the needle 3 fingerbreadths laterally to the midline of the sternal angle. For the axillary sites, the authors used the level of the xiphoid process at the sternal notch, which is also easily palpated on patients and typically corresponds to the fifth interspace. Of the three sites studied, the MHL appears to be the safest, since it has the least likelihood of having a vital structure in the path of a needle up to 10 cm in length, especially in patients who have had a prior sternotomy.
In conclusion, needle decompression of a suspected tension pneumothorax should be attempted in the midhemithoracic line at the level of the sternal angle using a needle at least 7 cm long inserted perpendicular to the horizontal plane. Half of all patients should have entry into their pleural space accomplished in under 3.1 cm and the remainder within 7 cm. |
