Discussion
A TPT is a potential cause of traumatic cardiac arrest, requiring immediate recognition and treatment by prehospital medical personnel with needle decompression. To be effective, the provider must successfully place the angiocatheter into the pleural cavity without injuring any surrounding neurovascular structures. The main factors that contribute to failure include improper anatomic location for insertion, improper angiocatheter length for the desired location, and CWT that exceeds the available catheter length.12 15
There has been debate about the specific site and length of the angiocatheter for NT. The three locations recommended are the second ICS-MCL, the fourth/fifth ICS-AAL, and the fourth/fifth ICS-MAL. In a systematic review and meta-analysis, Laan et al16 examined the CWT of these three recommended sites. They noted that the chest wall was thinnest at the fourth/fifth ICS-AAL (34.33 mm) compared with the second ICS-MCL (42.79 mm) and the fourth/fifth ICS-MAL (39.85 mm). Correspondingly, they noted the failure rate was also lowest at the fourth/fifth ICS-AAL (13%) compared with the other two sites (38% and 31%, respectively). As a result, they concluded that the fourth/fifth ICS-AAL may be a better option in patients with a suspected thicker chest wall or in patients in which a prior NT attempt had failed.16 Furthermore, Leatherman and colleagues17 noted that the fifth ICS-AAL was most stable for combat casualty transport. However, this was a cadaveric study involving a select BMI of 24 kg/m2, which does not represent our patient population.17
In addition to identifying the proper location, an appropriate needle length is also crucial for a successful catheter placement. Givens and colleagues18 challenged the previous recommendations of a 5 cm angiocatheter. Using CT measurements, they noted that a 5 cm catheter at the second ICS-MCL would fail in 25% of cases due to insufficient length. They therefore recommended that longer catheters should be considered, especially in women.18 Their findings were consistent with other researchers who reported failure rates of using a 5 cm angiocatheter to be as high as 94% and recommended using an 8 cm angiocatheter for NT.11 19 ATLS recently updated their recommendations to include placement of a 5 cm to 8 cm angiocatheter in the fourth/fifth ICS-MAL.5 The Tactical Combat Casualty Care guidelines also recommended placement of a 3.25 inch (8.25 cm) angiocatheter in either the fifth ICS-MAL or the second ICS-MCL.20 All EMS agencies within the ARMC serving region involved in this study use the 14 gauge or 16 gauge, 3.25 inch (8.25 cm) needle.
Based on the presented evidence, our study supports the recommendation of using the longer angiocatheter for NT for suspected TPT in all patient care settings. The second ICS-MCL was the preferred site for NT by prehospital personnel in 81 of 84 (96%) patients. At this site, 63% of patients had CWT >50 mm (see figure 2), which would render the shorter 5 cm angiocatheter ineffective. About 20% of patients had CWT ≥70 mm, which leaves little room for error even with the longer 8.25 cm catheter. Only 23 (27.4%) patients had the NT properly inserted into the pleural cavity based on CT findings. Although there was no statistically significant difference in mortality (91.3% vs. 82.0%, p=0.4994) between proper and improper insertion, the proper insertion group was associated with higher likelihood of survival to discharge, reinforcing the importance of appropriate application of NT in managing suspected traumatic TPT.
Figure 2Examples of chest wall thickness measurements in the second intercostal space of the midclavicular line (A), fourth intercostal space of the anterior axillary line (B), and fourth intercostal space of the midaxillary line (B).
Similar to prior studies, factors contributing to failed NT placement are multiple and some of these cases are demonstrated in figure 3. These findings suggest that enhanced training of prehospital personnel using techniques such as simulation or cadaver laboratories should be considered to improve outcome. Grabo et al21 noted that paramedics had a higher success rate of performing NT when trained with a cadaver (75%) as compared with traditional slides and lectures (35%). Additionally, the recent advancement in simulation models and techniques has drastically improved training in medically invasive techniques.22 Continuous and constructive performance feedback is needed from the agencies’ medical directors, regional trauma services, and when indicated from coroners.
Figure 3Examples of improper needle thoracostomy placements with the needle angled downward (A), upward (B), and too lateral (C).
The appropriateness of NT placement is more difficult to assess especially in a dynamically changing situation such as trauma in the prehospital setting. For the current study, 16 (22.5%) patients did not receive a TT during the trauma resuscitation, indicating that no pneumothorax or hemothorax was discovered on CT. The CT findings suggest that these 16 patients did not need NT in the prehospital setting. The actual rate may be potentially higher as it is impossible to determine if the pneumothorax discovered on CT was iatrogenically caused once NT has been performed. Even when appropriately indicated, there are potential serious complications with NT, including life-threatening hemorrhages.23 Additionally, the subsequent TT for any iatrogenic pneumothorax places the patient in unnecessary risk of complications, including hepatic, splenic, diaphragmatic, lung, and cardiac injuries.23 This study also observed few cases of iatrogenic injuries from inappropriate placement of NT in the abdominal cavity, spleen, and liver. These are demonstrated in figure 4. Therefore, strategies to minimize medically unnecessary NTs should be explored by EMS regulatory agencies throughout the USA.
Figure 4Examples of complications from improper needle thoracostomy placements: hepatic penetration (A), subdiaphragmatic placement with potential splenic penetration (B), and advancement of both needle and catheter into the thoracic cavity (C).
The Eastern Association for the Surgery of Trauma (EAST) trial led by Taghavi et al24 recently asserted that prehospital procedures (PHPs) in penetrating trauma patients impart no survival advantage and may be detrimental in urban settings. However, they did not address similar concerns for blunt trauma. Additionally, they admitted that there was an inherent bias as patients receiving PHPs were more severely injured. Furthermore, the EAST article did not specifically examine the time for transport, undoubtedly assuming the time would be minimal in an urban setting. These findings should encourage more thorough research to provide evidence-based recommendations with regard to penetrating trauma in urban settings with short transport time. The geographical location of ARMC is unique as it serves as a major trauma center in SBC, which is the largest geographical county in the USA. Transport time to ARMC may be significantly longer than the average US urban trauma center, and at times requiring air transport. In our study population, 42.9% of these patients arrived by air transport, indicating a longer transport time. Although the EAST trial has a different study composition from our study of nearly 70% blunt trauma, we agree with their suggestion that most prehospital NTs may not be indicated in the urban setting with a short transport time.
There is a new school of thought recommending treatment of suspected TPT in prehospital traumatic cardiac arrests with simple thoracostomy (ST) instead of NT.25 ST is a technique similar to TT but involves the release of the TPT using forceps and a gloved finger without placing the chest tube. This protocol was first implemented in the European prehospital arena with promising results. However, small studies in Italy and the UK both involved ST performed only by highly trained air medical personnel.26 27 Dickson and colleagues28 suggested that ST can be performed by specially trained paramedics in ground-based EMS agencies in the USA with good results. Our study suggests that serious considerations should be given to using ST to treat suspected TPT. Based on CWT, about one-fifth of patients would fail NT at all three recommended sites of insertion, even when using the longer 8.25 cm catheter. Additionally, using ST would also decrease the complications associated with improper needle placements. This will represent a major shift in policies regarding the scope of practice for paramedics in the USA and will require a robust educational program with strong oversight.
The diagnosis of a TPT is made solely on clinical suspicion and findings, which may include decreased breath sounds and hypotension. Unfortunately, other traumatic pathologies also present with similar clinical findings, such as hemorrhagic shock with concomitant rib fractures. Point-of-care ultrasound has been shown to have high sensitivity and specificity in diagnosing a pneumothorax when performed by emergency physicians.29 The emergence of smaller portable ultrasound machines may be an opportunity to improve quality of care in the prehospital setting.30 31 Future large-scale research should investigate if prehospital personnel can be appropriately trained to use this modality to improve their recognition of a TPT and decrease the rate of inappropriate NT placement.
The generalizability of findings in the current study may be limited by several factors. First, our sample of 84 patients were from one single level II trauma center, which represents only one geographical location. This might limit the generalization to other geographical locations. A multicenter study with a more inclusive patient population is warranted to confirm our findings. Furthermore, the total number of prehospital NTs cannot be determined as patients who do not achieve return of spontaneous circulation would not be transported to trauma centers. An open channel of communication among the trauma centers, regional EMS agencies, and the local corners would be ideal to assess the true incidence of inappropriate NT placement.
Additionally, this study does not address the difference between transport to trauma centers from police versus ground EMS agencies. Recent studies have noted that patients who sustained penetrating trauma and were transported to trauma centers by law enforcement (LE) had no difference in adjusted in-hospital mortality when compared with penetrating trauma transported by EMS agencies.32 33 For our study population, among the 26 patients who sustained penetrating trauma, 16 were transported by ground with a mortality rate of 25% (n=4), and 10 arrived by air with a mortality rate of 10% (n=1). The recently adopted policy of “scoop and run” by LE in Philadelphia may not translate well to a larger geographical area such as SBC. Tansley and colleagues34 have noted that longer travel time was associated with worse outcomes for victims of penetrating and blunt traumas. Based on the evidence presented in the prior studies, we recommend that the policy of “scoop and run” by either LE or EMS should be selective and encouraged for patients who have sustained penetrating trauma within a reasonable transport time to trauma centers.32–35