Interval between injection of contrast material and positive contrast cheliography affects accurate diagnosis of diaphragmatic hernia

The aim of this study was to evaluate the clinical, surgical and diagnostic imaging findings in 11 cats and 3 dogs with suspected acute and chronic traumatic diaphragmatic hernia, and to compare the results of positive contrast cheliography (peritoneography) taken immediately and 5 min after the injection of contrast material. Thoracic and abdominal radiography, ultrasonography, and positive contrast cheliography of all animals were performed. Eight cases were considered as acute and six cases were considered chronic. The contrast images taken immediately after the injection of contrast material revealed the contrast material in the thoracic cavity in 8/8 acute trauma patients, but in none of the chronic cases. In 5/6 of these cases contrast material was seen in the thoracal cavity only in additional images taken after 5 min. One patient was diagnosed with FIP and excluded from the study. Twelve cases had complete resolution and one animal died during the early postoperative period. Our results suggest that positive contrast cheliography performed immediately after the injection of contrast material may not reveal chronic cases of diaphragmatic hernia and a second imaging (or imaging after 5 min) is indicated in order not to overlook chronic cases. Cat, chronic, contrast medium, diaphragm, dog, peritoneography Traumatic diaphragmatic hernia most often develops as a result of blunt abdominal trauma (particularly motor vehicle accidents), resulting in sudden increase in abdominal pressure and subsequent disruption of the diaphragm which allows abdominal organs to migrate into the chest cavity (Schmiedt et al. 2003; Fossum 2007). Several reports in veterinary literature have described the pathophysiology, surgical approaches, and outcomes of traumatic diaphragmatic hernia (Wilson and Hayes 1986; Boudrieau and Muir 1987; Downs and Bjorling 1987; Minihan et al. 2004; Worth and Machon 2005). Herniation of abdominal organs into the thoracic cavity may result in the inability of the lung to inflate and, thus, respiratory dysfunction (dyspnea, tachypnea, cyanosis) is the most common presenting sign of reduced functional residual capacity (Garson et al. 1980; Wilson 1992). Other clinical signs such as a “tucked” (empty) abdomen or the presence of muffled heart sounds and/or absent lung sounds are helpful, but variably present (Worth and Machon 2005). Diaphragmatic hernia can be diagnosed by means of radiography, ultrasonography and surgery (Hay et al. 1989; Reichle and Wisner 2000; Hyun 2004; Kibar et al. 2006). Radiography is the initial imaging technique of choice in diagnosing traumatic diaphragmatic herniation and the most frequently reported radiographic findings are loss of the diaphragmatic line, masking of the cardiac shadow, dorsal or lateral displacement of lung fields, presence of gas stomach or intestines in the thoracic cavity, and pleural effusion (Garson et al. 1980; Sullivan and Lee 1989; Williams et al. 1998). Positive contrast cheliography (peritoneography) (Stickle 1984; Bumin et al. 1998; Kibar et al. 2006; Besalti et al. 2011) or noncardiac thoracic ultrasonography (Hay et al. 1989; Tidwell ACTA VET. BRNO 2015, 84: 173–179; doi:10.2754/avb201584020173 Address for correspondence: Nihal Y. Gul Satar Department of Surgery Faculty of Veterinary Medicine Uludag University,16059 Nilufer/Bursa, Turkey Phone: +90 224 2940839 Fax: + 90 224 2941202 E-mail: [email protected] http://actavet.vfu.cz/ 1998; Spattini et al. 2003; Minihan et al. 2004; Kibar et al. 2006) can be consulted to assist diagnosis in cases in which direct radiography proves to be inadequate. The liver is the most commonly herniated organ, with the stomach, small intestine, and spleen often involved in left-sided hernias, and the small intestine and pancreas in right-sided tears (Boudrieau and Muir 1987). It is known that the passage of contrast material from the abdomen into the thoracic cavity may not occur if adhesions are present, particularly in chronic cases (Kibar et al. 2006). Therefore, we decided to evaluate the clinical, surgical, and diagnostic imaging findings in 11 cats and 3 dogs with suspected acute and chronic traumatic diaphragmatic hernia and to compare the diagnostic accuracy of positive contrast cheliography taken immediately or 5 min after the injection of contrast material. Materials and Methods A total of 14 patients that were referred to our Teaching Hospital between 2012 and 2014 with suspected traumatic diaphragmatic hernia were included in this study. Information about the animals are presented in Table 1. For the radiographic diagnosis, dorsoventral and lateral thoracic and abdominal radiographs were taken. In nonconclusive cases, ultrasonography and positive contrast cheliography were also performed. A 7 MHz sector transducer was utilised during ultrasonographic examination (Sonoline Prima, Siemens, USA). Animals without dyspnea were laid on their right side, whereas animals displaying signs of dyspnea were maintained in dorsal position. The possible presence of abdominal organs in the thorax was bilaterally examined through the 5th–13th intercostal spaces on both the right and left sides. Furthermore, the abnormal position of the heart and the presence of pleural fluid were also evaluated during this examination. For positive contrast cheliography, animals were laid down on their left side. After routine presurgical preparation, sterile contrast material (Iohexol, Omnipaque®, 300 mgI/ml, GE Healthcare, Ireland) was slowly injected into the abdominal cavity at a dose of 1.1 mg/kg. Upon entry of the abdominal cavity with the needle, the piston of the injector was withdrawn and aspiration performed so that possible puncture of the abdominal organs could be revealed. The presence of air bubbles in the injector was indicative of the needle being located in the peritoneal cavity. The rear part of the animals was slightly elevated to ease the flow of the contrast material into the thoracic cavity if herniation was present (Kibar et al. 2006). Radiographs were taken in right and left latero-lateral and dorso-ventral positions immediately after injection. If the diagnosis of herniation was confirmed by positive contrast cheliography, the animal was referred for operation; in other cases a second positive contrast cheliography was performed after 5 min. In cases to undergo surgery, dexamethasone (0.5 mg/kg, i.v.) was administered immediately preoperatively to prevent reexpansion injury of lungs. General anaesthesia was induced with propofol (Diprivan®, 6 mg/kg, i.v., AstraZeneca, Turkey), or with diazepam (Diazem®, 0.2 mg/kg, i.v., Deva, Turkey) and ketamine (Alfamine®, 5 mg/kg, i.v., Egevet, Turkey) combination, and maintained with isoflurane (Forane®, Abbott, United Kingdom) delivered in oxygen via a circle system using a small animal anaesthetic machine (AMS 200, AMS, Turkey). The patients were positioned in dorsal recumbency with the head positioned toward the top of the table and the table tilted at 40 degrees to facilitate gravitation of abdominal viscera from the thorax. All dogs breathed × 12–14/min and cats × 16–18/min and an inspiratory:expiratory (I:E) ratio of 1:2 to achieve a target end-tidal CO2 between 35 to 45 mm Hg positive pressure ventilation with an automatic ventilator. Lactated Ringer’s solution was administered at 10 ml/kg/hr during anaesthesia. Cephazoline sodium (Iespor®, 20 mg/kg, i.v., I. E. Ulagay) was administered to prevent infection. Analgesia was provided with tolfenamic acid (Tolfedine®, 4 mg/kg, p.o., Novakim) administered postoperatively for 3 days. Surgical herniorrhapy was carried out via a ventral midline celiotomy approach to the diaphragm in all cases. Then abdominal organs in the thoracic cavity were drawn into the abdominal cavity and cleaned with Ringer’s lactate solution and rifamycin (RIF®, Kocak Farma Inc., Turkey). Hernia was repaired with monofilament polyglactin 910 (Vicryl®, Ethicon, United Kingdom) absorbable suture material in pattern of simple interrupted X form. After repairing the hernia, thoracocentesis was carried out with a three ways cannula placed through the diaphragm and the air within the thorax was aspirated with an injector to achieve negative pressure. The linea alba and skin were closed routinely. Postoperative radiographs were taken and range of pneumothorax and diaphragmatic line were controlled.