Rethinking Tension Pneumothorax
An interesting article in the Emergency Medicine Journal, “Tension Pneumothorax–Time for a Re-think?,” questions the traditional signs and symptoms of tension pneumothorax (TPT). The authors independently compiled and analyzed previous research dating from 1966 to 2003 determine if “classic” signs of TPT exist, and, if so, the rate of diagnosis. Essentially, the survey found that the majority of TPT cases do not present with classical signs, which necessitates a rethinking of how TPT recognition is taught (see Box 1). The authors also address the poor outcomes associated with needle decompression.
The article established that one must divide patients into two groups: 1) spontaneous breathing; 2) ventilated. This is important due to the ability of spontaneously breathing patients to compensate, thereby presenting differently. Group one displayed the ability to compensate during respiration with tension building (for a more detailed list of compensatory mechanisms, see Box 2). Up until time of death, cardiac output was reserved due to progressive tachycardia, incomplete transmission of positive IPP to the mediastinum (see Box 3 for group 1 signs and symptoms). Group two, however, presented differently due to not being able to compensate (see Box 4 and Table 1). Familiarity with the unique presentation of group 2 is obviously important because your patient may need to be ventilated en-route to a higher echelon of care.
The most intriguing findings were the poor correlation of TPT to mediastinal shift and tracheal deviation, two classic signs. The former is an inconsistent finding, except in children, due to mobility of their mediastinum. Moreover, tracheal displacement is also a poor indicator of mediastinal shift. In fact, in the this study, “it was absent in all 108 cases of suspected TPTs treated by paramedics with needle decompression and present in only 1 percent of those receiving needle decompression by flight nurses…. Even when present, the odds of experienced physicians diagnosing it are 50:50—that is, the same as tossing a coin.” Essentially, tracheal deviation is not diagnostic of TPT.
The authors also question the use of needle decompression as a diagnostic tool, due to associated morbidity (Box 8). For instance, “of 106 patients treated with tube thoracostomy by pre-hospital flight nurses, 38% had been attributable to failure of clinical improvement with needle decompression.” Furthermore, the authors are concerned with the use of needle decompression as a “rule-out” procedure, for no studies exist showing it as a sensitive test. Despite this, it is a therapeutic treatment and reduces time on scene when compared to chest tubes, which is important in the tactical environment. However, their research shows it is often used when no TPT is present, but that is an easier assessment after the fact. It should be highlighted that flutter valves, which are popular in the pre-hospital environment may cause re-tension according to their findings, so be vigilant in construction and re-assessment.
Overall, this is a detailed article that deserves consideration. It is worth your time to download the full version and prudently reassess your training and adjust accordingly.
References and tables from:
S Leigh-Smith and T Harris, “Tension Pneumothorax–Time for a Re-think?.” Emerg Med J 2005 22: 8-16.