The article in this issue by Iglesias-García et al. (2021) describes a case series of three horses that presented with subcutaneous emphysema due to dorsal tracheal perforations. All horses underwent surgical repair under general anaesthesia and trans-tracheal endoscopic guidance. Repair was performed via a window created by removal of the ventral third of the opposing tracheal ring. All three horses progressed well post-operatively. This case series adds another treatment option to the management strategies for tracheal perforation. The merits and potential drawbacks of these treatment options will be discussed.

Tracheal perforations in horses are most frequently due to trauma (Trostle et al. 1995; Saulez et al. 2005, 2009). Perforations can result in air efflux into the subcutaneous tissues, resulting in subcutaneous emphysema (Trostle et al. 1995; Prange 2018). This can then progress to pneumomediastimum and pneumothorax (Caron and Townsend 1984; Hance and Robertson 1992; Trostle et al. 1995). Another potential complication is the development of retropharyngeal emphysema (Marble et al. 1996). Although tracheal perforations frequently occur in the absence of tracheal ring disruption, it is also important to assess the tracheal rings, where possible, for evidence of fracture (Gillen et al. 2015). Furthermore, the presence of more than one tracheal perforation is not uncommon (Gillen et al. 2015) and time should be spent thoroughly evaluating the trachea endoscopically to ensure that all perforations have been visualised. In addition, the structures surrounding the trachea are also vulnerable to injury and the occurrence of concurrent oesophageal and tracheal perforations has been documented (Findley and Rubio-Martinez 2013).

Given the range and potential severity of complications discussed above, early intervention is crucial to ascertain the number and location of tracheal perforations, as well as stopping additional air dissecting through muscle and fascial planes. In more severe cases, for example, where a pneumothorax has already occurred, treatment must also focus on stabilisation as well as re-establishing negative pleural pressure (Sprayberry and Barrett 2015). In addition, the majority of cases require anti-inflammatory as well as antimicrobial therapy. Many treatment options for tracheal perforations exist and the clinician’s choice of treatment method will depend on the extent and location of the perforation.

Small tracheal perforations can be treated conservatively via a pressure bandage over the affected area (Prange 2018). Unfortunately, it is hard to determine what size of tracheal perforation can be considered ‘small’ and, therefore, likely to respond favourably to conservative therapy. Caron and Townsend (1984) and Gronvold et al. (2005) treated perforations of 1 cm² and 1 × 2 cm, respectively, with conservative management, with good results. However, it does not follow that every defect of this size should be managed conservatively. Other factors, including the horse’s presenting signs and the location of the perforation, also play a role. The literature suggests particular caution with dorsally located defects (Coco et al. 2020). Although conservative therapy has the benefit of low costs and negates the possibility of surgery-related morbidity, it cannot be considered suitable for larger defects. In addition, it is also less likely to be successful when multiple defects are present, particularly if one is located dorsally. Having said this Gronvold et al. (2005) reported a case with two tracheal perforations which resolved successfully following conservative management. One of the most crucial aspects of treatment when managing tracheal perforations conservatively is that the horse requires close monitoring to ensure subcutaneous emphysema is not worsening and to ensure that the horse is showing no evidence of respiratory difficulties. If this occurs, the conservative approach should be abandoned and another method used to reduce airflow from the tracheal defect.

Placing a tracheostomy tube either distal to the defect (Saulez et al. 2005), or through the perforation, when opposing dorsal and ventral perforations are present distally (Gillen et al. 2015), can result in positive outcomes. The approach appears to be particularly beneficial when either the primary defect (Saulez et al. 2005), or a secondary defect (Gillen et al. 2015), is located dorsally. Documented lesion sizes that have been managed in this way are less than 2 cm², as secondary intention healing of the perforation site is still required. The logic of the temporary tracheostomy tube is that it will divert airflow from the site of injury, reducing intraluminal pressure at the location of the lesion, and reducing airflow through the defect. The correct tube to place and its management schedule has not been proven; however, the author has had success with 16–18 mm short cuffed J-shaped endotracheal tubes in horses of approximately 450 kg. These tubes were filled with 15 mL of air to further divert airflow from the perforations. However, there are clear risks to inflating the cuff which should not be ignored. The pressure of the cuff should not be greater than the capillary perfusion pressure (20–30 mmHg) to avoid potential ischaemic necrosis of the trachea (Nordin 1997). This is difficult to assess and the author recommends close monitoring and regular endoscopy to ensure any subcutaneous emphysema is not increasing and also to monitor the integrity of the primary injury and the tracheostomy tube site.

Coco et al. (2020) describes the use of a fibrin sealant (Tisseel^{®1 1} Baxter, Round Lake, Illinois, USA.
) to resolve a 1 × 1.5 cm dorsally located tracheal laceration, in which conservative management had been unsuccessful. Coco et al. (2020) found the fibrin sealant easier to apply than using a medicinal gelatin sponge. The strategy used by the authors involved placing an endoscope through a tracheostomy incision and placing a needle, followed by a catheter at a slightly more proximal location, opposite the laceration. Four millilitres of fibrin sealant was applied to the defect, and Coco et al. (2020) reported that the glue hardened quickly. Twenty-four hours following the procedure, endoscopy revealed the sealant to no longer be visible; however, strands of fibrin were visible in the defect. Seven days following the procedure, the defect had filled with granulation tissue and had completely resolved after 24 days. Use of this product in horses is still in its infancy, and the author assumes that the application technique takes some practice; however, this method is an exciting alternative to more traditional techniques.

Perforations of the cervical trachea, where there is minimal loss of tissue and where there is little or no damage to the tracheal rings, can be debrided and sutured with 0 USP (3.5 M) absorbable suture in a simple interrupted pattern (Fubini et al. 1985). The location of the defect can present some difficulties, and Prange (2018) describes the necessity of having to rotate the trachea in some cases so achieve sufficient exposure of the lateral or dorsal aspect. In addition, drains may be required for 48–72 h (Prange 2018). Fubini et al. (1985) describe using 0USP (3.5 M) polyglactin 910 to close a 15 cm defect in the dorsal aspect of the trachea. In certain cases, when concurrent dorsal and ventral tracheal perforations exist, the ventral perforation can be used as a window through which to suture the dorsal perforation (Gillen et al. 2015). In this case, 2-0USP (3 metric) polydioxanone suture was placed in a simple interrupted pattern. In order to gain access to the dorsal aspect of the trachea when a ventral perforation is not present, Iglesias-García et al. (2021) removed the ventral aspect of the overlying tracheal ring in order to gain access to, and close, the dorsal perforation. Iglesias-García et al. (2021) used 3-0 USP (2M) copolymer of glycolide, ε-caprolactone and trimethylene carbonate in a simple interrupted pattern to close the defects. The ventral surgical site was closed at the end of the procedure. All the patients recovered well. The author suggests this would be a suitable approach when a fracture or marked injury to the ventral aspect of the tracheal ring is present, together with a dorsal perforation. Iglesias-García et al. (2021) performed this procedure under general anaesthesia as the patients exhibited respiratory difficulties. The author hypothesises that this procedure may be performed standing in more stable patients.

Larger perforations, particularly those that involve complete rupture between tracheal rings, may require resection and anastomosis (Scott 1978; Kirker-Head and Jakob 1990). This technique, while having positive results in the above reports, should not be undertaken lightly due to the potential morbidities, including difficulty in recovery due to application of a martingale apparatus (Kirker-Head and Jakob 1990), infection, peritracheal abscessation and the formation of intraluminal granulation tissue or mucosal webs (Prange 2018). Kirker-Head and Jakob (1990) describe anastomosis of a lacerated trachea, the free ends of which were separated by 15 cm. A potential complication of tracheal perforations themselves is tracheal stenosis. Barnett et al. (2014) describe removal of one tracheal ring to perform a resection and anastomosis to resolve this complication. The duration of convalescence and the degree of management required depend largely on the number of tracheal rings removed but wearing a harness for 3-4 weeks and box rest for a period of at least 4 weeks should be anticipated (Kirker-Head and Jakob 1990; Barnett et al. 2014; Prange 2018). Endoscopy, and potentially radiography, should be performed, and the external surgical sites should be completely healed prior to a return to activity.

Differences in healing times when different methods are utilised are hard to ascertain, due to the sparsity of cases and the differences in lesion size; however, I have attempted to briefly review this. The cases treated purely by conservative management had perforations between 1 cm² and 1 × 2 cm. Complete healing times were approximately 28 days; however, one defect had formed a fibrin seal after 8 days. One horse was declared normal after 2 months (Caron and Townsend 1984), and the other had returned to exercise after 3 months (Gronvold et al. 2005). The range of healing times achieved when a tracheostomy tube was placed is hugely variable, ranging from 7 (Saulez et al. 2005) to 20 days (Gillen et al. 2015). The cases with longer durations had concurrent dorsal and ventral perforations. Whether application of a fibrin sealant (Tisseel®¹) results in a more rapid resolution of a defect is unknown; however, Coco et al. (2020) reported the defect to have sealed in 7 days and to have resolved after 24 days. The technique used by Iglesias et al. (2021) resulted in a fibrin seal in evidence 2 days following surgical intervention, and by 10–13 days, the dorsal perforations had sealed. The 15 cm perforation discussed by Fubini et al. (1985) was discharged from hospital after 9 days, and 12 months later was reported to be exercising as normal. As expected, the perforations which cause sufficient injury to warrant a resection and anastomosis required a longer convalescence period. The case described by Kirker-Head remained in hospital for 35 days and exhibited a 70% reduction in tracheal lumen diameter at this time. Repeat endoscopy 5 months post-operatively revealed minimal cicatrisation at the anastomosis site. The patient described by Barnett et al. (2014) received repeat endoscopy at 6 weeks post-operatively, where the anastomosis site exhibited a mucosa web. This was subsequently transected and endoscopy at 24 weeks post-operatively confirmed a well-healed tracheal anastomosis. Unfortunately, the number of cases managed with different surgical techniques are too small to draw firm conclusions as to the optimum treatment method; however, the more recent technique described by Iglesias-García et al. (2021) shows promise.

As shown by Iglesias-García et al. (2021), cases of tracheal perforation typically have a good prognosis when treated promptly and appropriately. It is also important to be aware of potential injury to surrounding structures, and the possibility of subcutaneous emphysema resulting in pneumomediastinum and pneumothorax. Close monitoring, anti-inflammatory and anti-microbial therapy, as well as closing, or diverting the airflow from, the perforation are the mainstays of therapy. Iglesias-García et al. (2021) introduce an excellent technique to manage dorsal tracheal perforations, or concurrent, opposing dorsal and ventral tracheal perforations.

本期文章由 Iglesias-García等人撰写。( 2021 ) 描述了一个由三匹马组成的病例系列，这些马因背侧气管穿孔而出现皮下气肿。所有马匹均在全身麻醉和经气管内镜引导下进行手术修复。通过去除相对气管环的腹侧三分之一产生的窗口进行修复。三匹马在手术后都进展顺利。本病例系列为气管穿孔的管理策略增加了另一种治疗选择。将讨论这些治疗方案的优点和潜在缺点。

马的气管穿孔最常见的原因是外伤（Trostle et al .  1995 ; Saulez et al .  2005 , 2009）。穿孔会导致空气外流进入皮下组织，导致皮下气肿（Trostle et al .  1995 ; Prange 2018）。然后，该可进展为pneumomediastimum和气胸（卡隆和汤森1984 ;昂斯和Robertson 1992 ; Trostle等人。  1995年）。另一个潜在的并发症是咽后肺气肿的发展（Marble et al .  1996）。尽管在没有气管环破裂的情况下经常发生气管穿孔，但在可能的情况下评估气管环以获取骨折证据也很重要（Gillen等人，  2015 年）。此外，存在多个气管穿孔的情况并不少见（Gillen等人，  2015 年），应花时间通过内窥镜彻底评估气管，以确保所有穿孔都已可视化。此外，气管周围的结构也容易受到伤害，并且已经记录了并发食管和气管穿孔的发生（Findley 和 Rubio-Martinez 2013）。

鉴于上述并发症的范围和潜在严重程度，早期干预对于确定气管穿孔的数量和位置以及阻止额外的空气通过肌肉和筋膜平面解剖至关重要。在更严重的情况下，例如，已经发生气胸的情况下，治疗还必须侧重于稳定以及重建胸膜负压（Sprayberry 和 Barrett 2015）。此外，大多数病例需要抗炎和抗菌治疗。存在许多气管穿孔的治疗选择，临床医生选择的治疗方法将取决于穿孔的范围和位置。

小气管穿孔可以通过在受影响区域上的压力绷带进行保守治疗（Prange 2018）。不幸的是，很难确定多大的气管穿孔可以被认为是“小”的，因此可能对保守治疗有积极的反应。Caron 和 Townsend（1984 年）和 Gronvold等人。( 2005 ) 处理 1 cm ²穿孔和 1 × 2 cm，保守治疗，效果良好。然而，并不意味着应该对这种规模的每个缺陷进行保守管理。其他因素，包括马的表现体征和穿孔的位置，也起作用。文献建议特别注意背侧缺陷（Coco等人，  2020 年）。虽然保守治疗具有成本低的优点，并消除了手术相关并发症的可能性，但不能认为它适用于较大的缺损。此外，当存在多个缺陷时，它也不太可能成功，特别是如果一个位于背部。话虽如此，Gronvold等人。( 2005) 报告了一个有两个气管穿孔的病例，在保守治疗后成功解决。保守治疗气管穿孔时最重要的治疗方面之一是，马需要密切监测以确保皮下气肿没有恶化，并确保马没有出现呼吸困难的迹象。如果发生这种情况，应该放弃保守的方法，并使用另一种方法来减少来自气管缺损的气流。

当远端存在相对的背侧和腹侧穿孔时，将气管造口管放置在缺损远端 (Saulez et al .  2005 ) 或穿过穿孔 (Gillen et al .  2015 )，可以产生积极的结果。当原发性缺损 (Saulez et al .  2005 ) 或继发性缺损 (Gillen et al .  2015 ) 位于背侧时，该方法似乎特别有益。已记录的以这种方式处理的病灶大小小于 2 cm ²，因为仍然需要对穿孔部位进行二次修复。临时气管切开插管的逻辑是，它将气流从受伤部位转移，降低病变部位的管腔内压力，并减少通过缺损部位的气流。正确的管子放置及其管理时间表尚未得到证实；然而，作者在大约 450 公斤的马身上成功地使用了 16-18 毫米短袖带 J 形气管插管。这些管中充满了 15 mL 的空气，以进一步从穿孔转移气流。然而，给袖带充气存在明显的风险，不容忽视。袖带的压力不应大于毛细血管灌注压 (20-30 mmHg)，以避免气管潜在的缺血性坏死 (Nordin 1997）。这很难评估，作者建议密切监测和定期内窥镜检查，以确保任何皮下气肿不增加，并监测原发损伤和气管造口管部位的完整性。

可可等人。( 2020 ) 描述了使用纤维蛋白密封剂 (Tisseel ^{® 1 1} 巴克斯特，美国伊利诺伊州圆湖。
) 解决 1 × 1.5 cm 背侧气管撕裂伤，其中保守治疗失败。可可等人。( 2020 ) 发现纤维蛋白密封剂比使用药用明胶海绵更容易涂抹。作者使用的策略包括通过气管切开术切口放置内窥镜并放置针头，然后在稍近端的位置放置导管，与裂伤相对。纤维蛋白封闭剂的4毫升涂布到缺陷，和可可等。( 2020) 报告说胶水很快变硬。手术后 24 小时，内窥镜检查显示密封剂不再可见；然而，在缺损处可以看到纤维蛋白链。手术后 7 天，缺损处已充满肉芽组织，并在 24 天后完全消退。该产品在马匹中的使用尚处于起步阶段，笔者假设应用技术需要一定的实践；然而，这种方法是更传统技术的一种令人兴奋的替代方法。

宫颈气管，那里是组织，并且其中的损失最小的穿孔有很少或到气管环无损伤，可以清创，并用0 USP（3.5 M）以简单的断续图案吸收的缝线（富比尼缝合等。  1985 年）。缺损的位置可能会带来一些困难，Prange ( 2018 ) 描述了在某些情况下必须旋转气管才能充分暴露侧面或背面的必要性。此外，可能需要排水 48-72 小时（Prange 2018）。富比尼等人。( 1985 年) 描述了使用 0USP (3.5 M) polyglactin 910 来封闭气管背面 15 cm 的缺损。在某些情况下，当同时存在背侧和腹侧气管穿孔时，腹侧穿孔可用作缝合背侧穿孔的窗口（Gillen et al .  2015）。在这种情况下，2-0USP（3 公制）聚二恶烷酮缝合线以简单的间断模式放置。为了在不存在腹侧穿孔时进入气管的背面，Iglesias-García等人。( 2021 ) 移除了上覆气管环的腹侧，以便接近并关闭背侧穿孔。伊格莱西亚斯-加西亚等人。 ( 2021) 使用乙交酯、ε-己内酯和三亚甲基碳酸酯的 3-0 USP (2M) 共聚物以简单的间断模式封闭缺陷。在手术结束时关闭腹侧手术部位。所有患者均恢复良好。作者建议，当存在骨折或气管环腹侧明显损伤以及背侧穿孔时，这将是一种合适的方法。伊格莱西亚斯-加西亚等人。( 2021 ) 由于患者出现呼吸困难，因此在全身麻醉下进行了此手术。作者假设这个程序可以在更稳定的患者中进行。

较大的穿孔，尤其是那些涉及气管环之间完全破裂的穿孔，可能需要切除和吻合（Scott 1978；Kirker-Head 和 Jakob 1990）。这种技术虽然在上述报告中取得了积极的结果，但由于潜在的发病率，包括由于使用鞅（Kirker-Head 和 Jakob 1990）、感染、气管周围脓肿和形成管腔内肉芽组织或粘膜网（Prange 2018）。Kirker-Head 和 Jakob（1990 年）) 描述了气管撕裂的吻合术，其游离端相距 15 厘米。气管穿孔本身的潜在并发症是气管狭窄。巴内特等人。( 2014 ) 描述了移除一个气管环进行切除和吻合以解决这一并发症。恢复期的持续时间和所需的管理程度在很大程度上取决于移除的气管环的数量，但应预期佩戴安全带 3-4 周和至少 4 周的休息时间（Kirker-Head 和 Jakob 1990；巴内特等人。  2014 ;普兰奇2018）。应进行内窥镜检查，并可能进行放射线检查，并且在恢复活动之前，外部手术部位应完全愈合。

由于病例稀少和病灶大小不同，很难确定使用不同方法时愈合时间的差异；然而，我试图简要回顾一下。单纯保守治疗的病例穿孔在 1 cm ²和 1 × 2 cm 之间。完全愈合时间约为 28 天；然而，一个缺陷在 8 天后形成了纤维蛋白密封。一匹马被宣布为2个月（卡隆和汤森正常后1984年），和3个月后，其他已经回到训练（Gronvold等人。  2005）。放置气管切开插管时所达到的愈合时间范围变化很​​大，从 7 不等（Saulez et al .  2005) 到 20 天（Gillen等人，  2015 年）。持续时间较长的病例同时出现背侧和腹侧穿孔。使用纤维蛋白密封剂 (Tisseel® ¹ )是否能更快解决缺陷尚不清楚；然而，可可等人。( 2020 ) 报告缺陷已在 7 天内密封并在 24 天后解决。Iglesias等人使用的技术。（2021 年）在手术干预后 2 天导致纤维蛋白密封，到 10-13 天，背侧穿孔已密封。Fubini等人讨论的 15 cm 穿孔。 ( 1985 年) 9 天后出院，12 个月后据报道可以正常锻炼。正如预期的那样，造成足够损伤以保证切除和吻合的穿孔需要更长的恢复期。Kirker-Head 描述的病例在医院住院 35 天，此时气管管腔直径减少了 70%。术后 5 个月重复内窥镜检查显示吻合部位有极少的瘢痕形成。Barnett等人描述的患者。( 2014) 在术后 6 周接受重复内窥镜检查，其中吻合部位显示粘膜网。随后在术后 24 周进行横切和内窥镜检查，证实气管吻合术愈合良好。不幸的是，使用不同手术技术治疗的病例数量太少，无法得出最佳治疗方法的确切结论；然而，最近的技术由 Iglesias-García等人描述。（2021）显示出希望。

如 Iglesias-García等人所示。（2021 年），气管穿孔病例如果得到及时和适当的治疗，通常预后良好。了解对周围结构的潜在损伤以及皮下气肿导致纵隔气肿和气胸的可能性也很重要。密切监测、抗炎和抗微生物治疗以及关闭穿孔或从穿孔转移气流是治疗的主要手段。伊格莱西亚斯-加西亚等人。( 2021 ) 介绍了一种管理背侧气管穿孔或同时发生的对侧背侧和腹侧气管穿孔的出色技术。