2017-18 HSC Section 3 Green Book

m a d s e n e t a l c t a f o r a e r o d i g e t s i v e t r a c t i n j u r y f o l l o w i n g p e n e t r a t i n g n e c k i n j u r y

Introduction

Deep surgical emphysema was defined as surgical emphy- sema deep to the middle layer of the deep cervical fascia and/ or fascia colli and/or mediastinal emphysema, as seen on CTA and was correlated with an aggregate standard of reference for ADTI as demonstrated on water-soluble contrast swallow (WS-swallow), endoscopy, neck exploration, or direct visuali- zation on clinical examination. This allowed us to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of this particular finding in identifying ADTI.

Penetrating neck injury (PNI) is ominous due to the density of vital structures found in this confined anatomic region. Although the timeous and accurate delineation of all injuries is essential, the appropriate imaging strategy in PNI remains controversial. 1 e 9 There exist a battery of low yielding diag- nostic investigations, some of which are invasive and asso- ciated with a not negligible complication rate. These investigations are intended to assess the vascular tree as well as the adjacent aerodigestive tract and traditionally included formal invasive catheter-directed angiography (CDA), upper digestive tract contrast studies as well as flexible and rigid endoscopy and bronchoscopy. Computed tomography angi- ography (CTA) emerged over the last decade as one of the most commonly used modalities to assess the vascular tree after PNI. 10 e 19 This was mostly due to its convenience, as it does not require arterial puncture and catheter manipulation, can be performed rapidly and does not require a sterile field, local anesthesia, complex analgesia, specialized staff or an awake and cooperative patient. The current evidence suggests that CTA is a highly sensitive and specific investigation for the assessment of the vasculature in the neck. 10,11,14,17,18 In addition CTA can provide information about adjacent aero- digestive tract injuries (ADTIs) and therefore has the potential to be an all-in-one type of investigation for PNI possibly reducing the need for contrast studies and/or endo- scopy. 12,16 e 19 In our high-volume trauma service over the last decade, CTA has been widely used in the assessment of PNI and we generally have come to accept that ADTI is associated with surgical emphysema in the deeper fascial planes of the neck or mediastinum, and if this cannot be demonstrated on CTA then further investigation for ADTI is superfluous. This has made CTA a de facto all purpose investigation for PNI in our service. The aim of this retrospective study was to audit our experience with CTA for PNI and assess whether CTA does indeed reliably identify patients with potential ADTI after PNI. This study was undertaken at the Pietermaritzburg Metro- politan Trauma Service, South Africa. Pietermaritzburg Metropolitan Trauma Service maintains a prospective digital trauma registry that captures data on admitted trauma pa- tients. Ethics approval to maintain the registry has been ob- tained from the Biomedical Research Ethics Committee (BCA221/13 BREC) of the University of KwaZulu-Natal and from the Research Unit of the Department of Health. 20,21 Searching the trauma registry retrospectively identified all eligible patients for the study e patients investigated with CTA for PNI between January 2011 and November 2014. Exclusion criteria were death on arrival and patients with PNI not investigated with a CTA. Additional data were retrieved from hospital records as required. Radiologic reports of CTA studies were assessed for vascular injuries and/or radiologic images were reviewed for findings of deep surgical emphysema. Other injuries to bony structures and nonarterial soft tissue were also documented. Patients and methods

Classification

Neck wounds were classified into the traditional three zones of the neck as described by Roon and Christensen. 22

Selective investigation

We manage patients with PNI according to Advanced Trauma Life Support (ATLS) protocols. 23 Nonresponders and transient responders are expedited to the operating room. Responders or stable patients are managed selectively. All patients with PNI secondary to a gunshot wound (GSW) undergo mandatory investigation with CTA, whereas patients with injury due to stabwounds (SW) are investigated selectively depending on the presence of symptoms and clinical findings of injury. Table 1 summarizes symptoms and findings suggestive of injury to the vascular tree or aerodigestive tract, which will prompt us to investigate these patients. Invasive CDA is reserved for cases with equivocal CTA findings or for cases amenable to endo- vascular therapy. CTA images are obtained by the use of two 64 slice multi detector comptuerized tomographic scan units (Toshiba and Siemens), acquiring transverse sections of 0.6- mm thickness, from the base of the skull to the top of the aortic arch, reconstructed to section thicknesses of 2-3mm. We use water-soluble contrast studies selectively to confirm pharyngeal or esophageal injuries when clinically suspected or when injury is suggested by the finding of surgical emphysema on CTA. Flexible endoscopy is reserved for selected cases such as the unconscious patient or patients with equivocal findings on WS-swallow. We do not use rigid endoscopy to assess the digestive tract post-PNI in our service. As most minor tracheal and bronchial injuries have a benigncourse, wedonot routinely confirm these injuries by bronchoscopy as long as a digestive tract injury (DTI) has been excluded as the cause of surgical emphysema. Only if the patient remains symptomatic will further investigation of the airway be performed.

Results

Demographics, clinical data, and outcome

Over the 4-y period 383 patients underwent a CTA for PNI. The mean age was 29.5 y, and 90.1% (345/383) were male. The most commonly involved zone of the neck was zone I with 42.3% (162/383) of the patients having PNI localized to this zone only. A total of 80% (331/383) of patients had PNI secondary to SW as opposed to 13.6% (52/383) who sustained a GSW. Nineteen

48