2017-18 HSC Section 3 Green Book

j o u r n a l o f s u r g i c a l r e s e a r c h o c t o b e r 2 0 1 6 ( 2 0 5 ) 4 9 0 e 4 9 8

Table 8 e Comparative data on ADTI as demonstrated by CTA. Author Year Number of patients CT scanned Confirmed airway injury

Confirmed DTI

False positive for ADTI

False negative for ADTI

Munera

2000

60

0

0

0

0

Mazolewski

2001

14

2

0

0

0

Gracias

2001

23

0

0

0

0

Munera

2002

175

4

0

0

0

Gonzalez

2003

42

0

4

0

2 (? surgically relevant, as only minor injuries)

Inaba

2006

91

6

1

4 (tracheal)

0

Inaba

2012

225

3

3

3 (esophageal)

0

Current study assessing relevance of surgical emphysema

2016

383

11

38

70 (when using deep surgical emphysema and excluding all patients with pneumothoraces)

2 (all surgically irrelevant)

ADTI ¼ aerodigestive tract injury; CTA ¼ computed tomography angiography; DTI ¼ digestive tract injury.

ADTIs are rare after PNI and patients with isolated ADTIs might present with minimal clinical signs and symptoms. 27 Palpable subcutaneous emphysema or crepitus on physical neck examination is suggestive of ADTI that might require operative intervention. 28 In a previous study from our parent institution investigating the conservative manage- ment of 106 patients with PNI, 44 patients were identified with clinical or radiologic evidence of ADTI. The most common presentation of ADTI was found to be odynophagia and subcutaneous emphysema. Only 29 of these patients with odynophagia on swallowing a mouthful of water were investigated further by contrast swallow which revealed an esophageal injury in only four patients. The remaining pa- tients had no clinically significant missed ADTI after a period of observation suggesting that odynophagia is a sensitive but also not a very specific finding of DTI. 29 In a follow-up study of 220 patients with odynophagia secondary to PNI investigated with a contrast study only 28 patients were demonstrated to have an injury of which seven pa- tients also had subcutaneous emphysema. No injuries were missed. 30 In agreement with these earlier studies from our parent institution, we found that the most common clinical findings of ADTI were odynophagia and subcutaneous emphysema. Table 8 summarizes the literature on the use of CTA for the identification of ADTI after a PNI. 10 e 12,14,15,17,18 It is apparent that this current series contains a very high number of false positives for ADTI compared with other large series and there are a number of potential explanations for this. Previous pa- pers have been vague with defining what determines a CTA suspicious for an ADTI, and the number of ADTIs in the re- ported literature makes it difficult to make definitive comment on the suitability of CTA for the assessment of ADTI. In addition, there is lack of consensus as to what CTA findings identify an ADTI. There is agreement that further imaging can be avoided if the trajectory can be shown to be away from vital structures and a number of these studies have used trajectory as an indicator of injury. This is certainly relevant for missile

trajectories secondary to GSW, but it is challenging to deter- mine the trajectory from an SW, which constitute the vast majority of our patients. 12,31 Our current data suggest that deep surgical emphysema is a good indicator of potential ADTI. Using this method, we found a sensitivity, specificity, PPV, and NPV of CTA of 94.1%, 71.9%, 30%, and 98.9%, respectively, for the detection of ADTI. This is, however, not applicable to patients with pneumo- thoraces which are associated with the same radiologic finding. Including only surgically relevant injuries increases the sensitivity and NPV of this radiological finding to 100%. This is in keeping with data from previous studies, which highlighted the excellent sensitivity of CTA in detecting ADTI, but it is low specificity. 20,21 The presence of deep surgical emphysema as an indicator of ADTI is less specific than trajectory and leads to more false positive studies, but its absence excludes the possibility of an ADTI. We had been able to delineate all missile tra- jectories, as this is the case with most GSW, many CT studies suspicious of ADTI based purely on the finding of deep surgical emphysema could have been dismissed if the trajectory was found to be distant to vital structures. As imaging technology continues to improve CT-contrast esophagography may well become standard practice to exclude ADTIs. This can be done in conjunction with CTA as reported in a recent study from another South African trauma unit. These authors prospectively administered oral contrast within 5 min of commencement of the CTA exam- ination. They reported a sensitivity of 95.0% and specificity of 85.4%-91.5% for CT esophagography. 32 Our data suggest that all stable patients with signs sug- gestive of a vascular injury after an SW of the neck injury require imaging with CTA. All asymptomatic patients with PNI secondary to a GSW should be imaged. Patients with symp- toms suggestive of an ADTI or with deep surgical emphysema on CTA require further investigation to exclude an ADTI. Our data suggest that if no deep surgical emphysema is identified on CTA further imaging is unnecessary.

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