Outcomes, including death, in dogs with pneumothorax following nasogastric feeding tube misplacement in the tracheobronchial tree: 13 cases (2017–2022)

Adesola Odunayo Department of Small Animal Clinical Science, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Meredith't Hoen Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA

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Jacob Wolf Department of Small Animal Clinical Science, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Kristen Marshall Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN

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Kara Osterbur Department of Emergency and Critical Care, Veterinary Specialty Center, Bannockburn, IL

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Kathleen Maxwell Department of Small Animal Clinical Science, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Abstract

OBJECTIVE

Complications of feeding tube placement are uncommon, but life-threatening pneumothorax has been reported in human and veterinary patients during feeding tube placement. This article describes the development of pneumothorax and the outcome associated with misplacement of nasogastric (NG) tubes in the tracheobronchial tree in 13 dogs.

ANIMALS

13 dogs being treated for various medical conditions that had NG tubes placed in 4 hospitals.

PROCEDURES

A review was carried out of the medical records of 13 dogs that developed pneumothorax after misplacement of NG tubes between 2017 and 2022.

RESULTS

14 dogs out of 4,777 (0.3%) developed pneumothorax as an adverse effect of NG tube misplacement in the tracheobronchial tree. One dog was excluded due to incomplete medical records. The feeding tube size ranged from 5F to 10F, and the most common tubes utilized were polyurethane tubes with flushing stylets. Nine out of 13 dogs developed evidence of respiratory compromise after the NG tube was placed. Eleven dogs required thoracocentesis, and 5 dogs had thoracostomy tubes placed. Five dogs suffered cardiopulmonary arrest after developing pneumothorax, with 3 of 5 undergoing cardiopulmonary resuscitation. Two out of 3 dogs that underwent cardiopulmonary resuscitation were discharged from the hospital. Five of 13 dogs were successfully discharged from the hospital, while 5 dogs died or were euthanized because of the pneumothorax.

CLINICAL RELEVANCE

Pneumothorax is a rare but potentially life-threatening complication of NG tube placement in dogs and may lead to death if not immediately addressed. Practitioners should be aware of this complication and be ready to perform thoracocentesis quickly if appropriate.

Abstract

OBJECTIVE

Complications of feeding tube placement are uncommon, but life-threatening pneumothorax has been reported in human and veterinary patients during feeding tube placement. This article describes the development of pneumothorax and the outcome associated with misplacement of nasogastric (NG) tubes in the tracheobronchial tree in 13 dogs.

ANIMALS

13 dogs being treated for various medical conditions that had NG tubes placed in 4 hospitals.

PROCEDURES

A review was carried out of the medical records of 13 dogs that developed pneumothorax after misplacement of NG tubes between 2017 and 2022.

RESULTS

14 dogs out of 4,777 (0.3%) developed pneumothorax as an adverse effect of NG tube misplacement in the tracheobronchial tree. One dog was excluded due to incomplete medical records. The feeding tube size ranged from 5F to 10F, and the most common tubes utilized were polyurethane tubes with flushing stylets. Nine out of 13 dogs developed evidence of respiratory compromise after the NG tube was placed. Eleven dogs required thoracocentesis, and 5 dogs had thoracostomy tubes placed. Five dogs suffered cardiopulmonary arrest after developing pneumothorax, with 3 of 5 undergoing cardiopulmonary resuscitation. Two out of 3 dogs that underwent cardiopulmonary resuscitation were discharged from the hospital. Five of 13 dogs were successfully discharged from the hospital, while 5 dogs died or were euthanized because of the pneumothorax.

CLINICAL RELEVANCE

Pneumothorax is a rare but potentially life-threatening complication of NG tube placement in dogs and may lead to death if not immediately addressed. Practitioners should be aware of this complication and be ready to perform thoracocentesis quickly if appropriate.

Introduction

Nasogastric (NG) and nasoesophageal (NE) feeding tubes are widely used to provide enteral nutrition in veterinary medicine.1 Enteral nutrition increases blood flow to the gut, maintains mucosal integrity, preserves the gut-blood defense barrier, reduces bacterial translocation, and enhances the role of the gastrointestinal tract as an immune organ.2 NG and NE feeding tubes are relatively inexpensive, readily available, easy to place, and can be used to administer nutrition, fluids, drugs, or contrast material.1,3 NG tubes are also utilized in gastric decompression and evaluating gastric residual volumes.

Complications associated with placement of NG and NE feeding tubes are usually mild and self-limiting. Those complications may include epistaxis, rhinitis, and misplacement in the tracheobronchial tree.4,5 However, rare but life-threatening complications including tracheal perforations, pneumothorax, pulmonary hemorrhage, enteric perforation, intracranial entry, and death have been reported in human patients.2,5,6 A recent case report1 described fatal complications in 2 dogs associated with NG tube misplacement in the tracheobronchial tree. Both of the dogs developed pneumothorax after NG tube placement, and both died as a result of the pneumothorax.

The objective of this case series was to describe the development of pneumothorax and the outcome associated with misplacement of NG tubes in the tracheobronchial tree in 13 dogs treated at 4 academic and multispecialty hospitals.

Materials and Methods

Dogs were retrospectively enrolled between January 2017 and July 2022 in a multicenter study including 3 academic institutions and 1 multispecialty practice. Electronic medical record databases as well as patient safety report databases were searched for “pneumothorax,” “nasogastric tube,” “nasoesophageal tube,” and “canine.” The inclusion criteria included dogs that had NG or NE tubes placed and developed pneumothorax due to misplacement of the feeding tube in the tracheobronchial tree. The following information was retrieved from the patients’ medical records: age at presentation; breed; sex; presenting complaint; reason for feeding tube placement; feeding tube size, length, and manufacturer; type of sedation administered during tube placement; technique used to place feeding tube; complications noted during feeding tube placement; thoracic radiographic findings; clinical findings that indicated pneumothorax had developed; volume of air removed with thoracocentesis; placement of thoracostomy tubes; clinical management of the case; and patient outcome. Feline records and cases with incomplete medical records were excluded.

The feeding tubes were placed in all institutions using either a standard or novel technique.7 For the standard technique, the NG tube was placed by measuring from the tip of the nose to the last rib. The feeding tube was then passed to the premeasured length. For the novel technique, the tube was premeasured from the nose to the thoracic inlet as well as from the nose to the last rib. The tube was then passed to the premeasured thoracic inlet length and aspirated to ensure negative pressure before advancing all the way to the premeasured length of the last rib.

Descriptive statistics were performed using an online statistics software.8 Continuous data were tested for normal distribution using the Shapiro-Wilk test. Data that were not normally distributed are reported as median with IQR.

Results

Signalment, presenting complaint, and reason for NG feeding tube placement

Across all 4 institutions during the study period, 4,777 dogs had NG or NE tubes placed. Fourteen (0.3%) dogs developed pneumothorax secondary to feeding tube misplacement during NG tube placement. No dog had an NE tube placed. One dog was excluded from the study because of incomplete medical records. A summary of the dogs’ ages, weight, breed, presenting complaint, and reason for NG tube placement is outlined elsewhere (Supplementary Table S1). The median patient weight was 7.4 kg (range, 1.87 to 28.2 kg; IQR, 10.6), with the most common reason for NG placement being nutritional support.

Sedation, tube size and type, placement technique, and difficulty passing nasal feeding tube

Six dogs had sedation administered before the NG tube was placed. A summary of sedatives used is outlined elsewhere (Supplementary Table S2). Three dogs did not require sedation, and it was unclear from the medical records whether sedatives were administered to 2 dogs. NG tubes were placed under general anesthesia in 2 endotracheally intubated dogs. One of those 2 dogs had just had a ventral slot performed, and the other tube was placed in a dog that was being mechanically ventilated for acute respiratory distress.

The feeding tube size ranged from 5F to 10F, with a length of 55 to 140 cm for dogs for which this information was available. Eleven dogs did not have weighted tubes, while 2 dogs had weighted tubes utilized. All tubes utilized were polyurethane tubes with flushing stylet (MILA International Inc), except for 1 dog in which a red rubber polyvinyl chloride tube (Covidien) was placed due to the small size of the dog.

The feeding tube was placed using the standard technique in 11 dogs and the novel technique in 1 dog. For 1 dog, there was no indication in the record of which technique was used to place the NG tube.

There were no difficulties noted when placing the NG tube in 12 dogs. It was not clear from the record whether there were any difficulties noted when placing the tube in 1 dog.

Eleven dogs had the NG tube aspirated after tube placement. Negative pressure was obtained in 4 of the 11 dogs on aspiration of the tube after placement based on the premeasured length. In 1 dog for which negative pressure was obtained, the individual who placed the tube felt like it was misplaced even after negative pressure was obtained, so it was removed and immediately replaced. Gastric contents were retrieved after the second placement. In 7 dogs, there were no records of whether negative pressure was attained after tube placement and aspiration. There was no record of whether the NG tubes were aspirated after placement in 2 dogs.

Pertinent findings after NG tube placement

Nine dogs developed respiratory distress and/or evidence of respiratory compromise after the NG tube was placed. In 3 of the 9 dogs, respiratory distress was estimated to happen immediately after the tube was placed. It took about 17 minutes to recognize respiratory distress in 1 dog. In 3 dogs, the exact time until respiratory distress was identified was not recorded in the medical record. For both dogs under general anesthesia, desaturation (SpO2 < 95%), poor ventilatory compliance during manual ventilation, and respiratory difficulty were noted when the NG tube was placed. This happened after approximately 6 and 20 minutes, respectively, after NG tube placement. End tidal CO2 measurement consistent with tracheal intubation was obtained from the NG tube in one of the intubated dogs, and a laryngeal examination confirmed placement in the airway.

Three dogs did not have any visible respiratory distress at the time the misplaced tube was identified. One of the 3 dogs was found apneic in the cage about 10 minutes after the NG tube was found to be misplaced and had been removed. Respiratory distress had not been noted in that dog before it was found apneic.

Eleven dogs had thoracocentesis performed. One dog did not require thoracocentesis due to the absence of clinical signs. There was no intervention performed in another dog that died shortly after the NG tube was removed from the tracheobronchial tube due to its “do not resuscitate” (DNR) status. Of the 11 dogs that had thoracocentesis performed, 3 dogs had a continuous pneumothorax, while 5 dogs had a range of 1.5 to 96 mL/kg of air removed (Supplementary Table S2). The volume of air removed via thoracocentesis was not noted in 3 dogs.

Five dogs had thoracostomy tubes placed. In 3 of the 5 dogs, negative pressure was not obtained during thoracocentesis due to continued pneumothorax, prompting placement of the thoracostomy tubes. One dog was emergently intubated due to the severity of its respiratory distress and subsequent cardiopulmonary arrest (CPA). As such, both the thoracocentesis and thoracostomy tube placement occurred while the dog was intubated. That dog had thoracostomy tubes placed after removing approximately 96 mL/kg of air via thoracocentesis, while the volume of air removed in the final dog with thoracostomy tubes placed was not recorded. A continuous suction device was utilized in all dogs with thoracostomy tubes placed. The continuous suction device indicated continued air production for a range of about 3 to 24 hours, and the thoracostomy tubes were in place for about 18 to 72 hours before they were removed. One dog had continuous production of air from the thoracostomy tube throughout the period of mechanical ventilation until it died.

In 3 dogs, 1.5 to 35 mL/kg of air was removed via 1 thoracocentesis procedure each. None of these 3 dogs had thoracostomy tubes placed. Three dogs died or were euthanized after thoracocentesis.

Thoracic imaging pre– and post–NG tube placement

Nine of the 13 dogs had thoracic radiography performed at some point before the NG tube was placed. All radiographic images were interpreted by a board-certified radiologist. None of the dogs with radiographic images obtained before NG tube placement had an underlying pneumothorax. Five of the 13 dogs had a normal thorax. One dog had evidence of mild cardiomegaly, and another dog had a diffuse structured interstitial pattern. One dog had a diffuse structured interstitial pattern that could have been attributed to the dog’s age and/or obesity with thin pleural fissure lines that may have represented age-related fibrosis or a small amount of pleural effusion. Another dog had evidence of a miliary pulmonary pattern with peribronchial coalescing infiltrates and lymphadenopathy. No dog had CT of the thorax performed before NG tube placement.

Ten out of 13 dogs had post–NG tube placement thoracic radiography. All radiographic images except one were interpreted by a board-certified radiologist. All 10 dogs had evidence of a misplaced NG feeding tube in the tracheobronchial tree (Figures 13). Three dogs that did not have radiographs taken had evidence of respiratory distress soon after the NG tube was placed, prompting thoracocentesis. One dog had a thoracic CT performed after thoracocentesis and thoracostomy tubes had been placed. The CT revealed a severe mixed pulmonary pattern (miliary pattern coalescing into areas of alveolar pattern with air bronchograms affecting all lung lobes). The radiographic changes for that dog were suggestive of metastatic neoplasia, fungal pneumonia, or, less likely, granulomatous or inflammatory underlying etiologies.

Figure 1
Figure 1

Right lateral thoracic radiographic images immediately before (A) and after (B) correction of misplaced nasogastric (NG) tube in an anesthetized 9-year-old castrated male mixed-breed dog enrolled in a retrospective case series of 13 dogs with pneumothorax after NG feeding tube misplacement in the tracheobronchial tree between January 1, 2017, and July 31, 2022. A—The NG tube (star) and endotracheal tube (arrow) are seen along the plane of the trachea. B—The NG tube (star) has been repositioned within the plane of the esophagus, and there is severe pneumothorax (circle) with collapse of the lung lobes (triangle). This dog survived to hospital discharge.

Citation: Journal of the American Veterinary Medical Association 261, 10; 10.2460/javma.22.12.0585

Figure 2
Figure 2

Right lateral thoracic radiographic images immediately before (A) and after (B) contrast administration in a 10-year-old spayed female Miniature Poodle in the study described in Figure 1. A—The NG tube (star) is seen along the plane of the trachea. B—The NG tube (star) remains within the plane of the trachea and contrast (oval) is administered through the misplaced tube into the pulmonary parenchyma. This dog did not survive to hospital discharge.

Citation: Journal of the American Veterinary Medical Association 261, 10; 10.2460/javma.22.12.0585

Figure 3
Figure 3

Right lateral thoracic radiographic image of a 10-year-old female spayed mixed-breed dog in the study described in Figure 1. The NG tube (star) is seen along the plane of the trachea, leading to mild pneumothorax (rectangles) throughout the pleural space. Radiopaque circles over the cardiac silhouette are ECG pads. This dog did not survive to hospital discharge.

Citation: Journal of the American Veterinary Medical Association 261, 10; 10.2460/javma.22.12.0585

Case management and outcome

Five (38%) dogs were successfully discharged from the hospital after resolution of the primary disease for which they were hospitalized. Four of 5 dogs that had thoracostomy tubes placed survived to discharge.

Five dogs developed CPA because of the pneumothorax. CPR was performed in 3 of 5 dogs with return of spontaneous circulation (ROSC) achieved in all 3 dogs. One of the 3 dogs was euthanized after ROSC, and the remaining 2 dogs survived to discharge from the hospital. One of the 2 dogs discharged after ROSC had been on a mechanical ventilator shortly after admission to the emergency room for hypoventilation secondary to cervical intervertebral disc disease. The NG tube misplacement occurred shortly after a ventral slot (C3-C4) was performed, about 24 hours after the dog presented. CPR was performed for about 2 minutes with 1 dose of epinephrine (0.01 mg/kg, IV) and atropine (0.04 mg/kg, IV) given. That dog was discharged after 14 days in the hospital and did not have any further complications from the NG tube misplacement. The second dog was hospitalized for treatment of leptospirosis, and an NG tube was placed to provide nutrition. The patient developed respiratory signs almost immediately after removal of the misplaced NG tube. The patient was given atropine (0.04 mg/kg, IV) for bradycardia and underwent CPA soon after. The patient was intubated, and CPR was performed for less than 1 minute before ROSC. Thoracocentesis was performed during CPR and continuous pneumothorax was present, so a thoracostomy tube was placed after ROSC. The thoracostomy tube remained in place for about 24 hours but was only productive for about 3 hours. The patient was discharged on day 8, 6 days after the NG tube misplacement.

Four (30.7%) dogs died as a direct result of respiratory distress and presumed hypoxia secondary to the NG tube misplacement–induced pneumothorax. One of those dogs had an episode of severe respiratory distress as soon as the misplaced NG tube was identified and removed from the airway. The dog developed CPA immediately after respiratory distress was noted. CPR was not attempted, as the owner had elected a DNR status. Postmortem radiography revealed severe pneumothorax. Another dog underwent witnessed CPA about 5 minutes after the misplaced NG tube was removed, and CPR was not attempted as the owners had also elected a DNR status. Thoracocentesis at the time of CPA confirmed the presence of pneumothorax, but the volume of air removed was not recorded.

One dog died about 36 hours after NG tube misplacement while being mechanically ventilated. Thoracostomy tubes inserted in this dog continued to produce air intermittently the entire time the dog was on the ventilator.

Three (23%) dogs were euthanized, with 1 of those 3 euthanasias occurring directly as a result of the development of a pneumothorax. One dog developed CPA and was successfully resuscitated with CPR and thoracocentesis. CPR was performed in this dog for about 3 minutes with 1 dose of epinephrine (0.01 mg/kg, IV) and atropine (0.04 mg/kg, IV) given. The owner elected euthanasia right after ROSC due to the critical nature of the patient prior to the NG tube replacement and uncertain long-term prognosis. Another dog was euthanized for reasons unrelated to the NG tube misplacement, as the dog continued to do poorly in the hospital. Euthanasia was performed about 9 days following development of the pneumothorax event. The last dog was discharged to be euthanized on day 6 of hospitalization due to worsening liver values and poor response to treatment. This dog required additional thoracocentesis and oxygen therapy 72 hours after the NG tube misplacement, but the recurrent pneumothorax did not appear to contribute to the decision to euthanize the dog.

One dog had a necropsy performed. On necropsy, there was evidence of pulmonary fibrosis and emphysema and fibrous adhesion of the right middle lung lobe to the cranial mediastinum, which may potentially have been due to aspiration pneumonia. That dog also had evidence of pancreatitis, hepatic lipidosis, and splenic infarcts. One dog had postmortem biopsies of the spleen and lungs, which revealed splenic hemangiosarcoma with pulmonary metastasis. There was no evidence of gross lesions secondary to the NG tube in both dogs, although a complete necropsy was not performed in the second dog.

Discussion

To the authors’ knowledge and based on the review of the available literature, this was the largest case series describing the outcome of dogs that developed iatrogenic pneumothorax after misplacement of an NG tube in the tracheobronchial tree. A recent case report of 2 dogs demonstrated fatal outcomes following the misplacement of NG tubes in both dogs.1 While the incidence of this complication was very rare (14/4,777 [0.3%]), the mortality rate in this case series was also quite high, as 41% (5/13) of dogs either died or were euthanized as a result of the complication. This highlights the fact that misplacement of NG tubes should be treated as an emergency, with detailed attention and monitoring focused on the affected patient. It also stresses the importance of monitoring all patients undergoing NG tube placement for respiratory changes following the procedure, and any change in the patient’s respiratory status should be acted upon promptly.

Clinical signs of the pneumothorax, primarily characterized by respiratory distress, appeared to occur fairly quickly in the affected dogs. In dogs with data available for review, clinical signs were seen right after tube placement in 3 of 8 (38%) dogs. While it took as long as 17 minutes for clinical signs to be noted in 1 dog, it is reasonable to state that the first 20 minutes are the most crucial time for development of respiratory distress after NG tube misplacement and all dogs with feeding tubes placed should be closely monitored during this period. One dog had recurrent pneumothorax with clinical signs developing 72 hours after the first thoracocentesis. It is difficult to say what percentage of the air was removed from the pleural space during the original thoracocentesis, since a very small volume (3 mL/kg) was initially obtained. It is anecdotally thought that it takes about 30 mL/kg of air to cause respiratory distress in dogs.9,10 This is consistent with the dogs in this case series undergoing thoracocentesis, as in most cases when respiratory distress was noted, greater than 35 mL/kg of air was obtained via thoracocentesis, with negative pressure unattainable in 3 dogs due to continuous pneumothorax. It might be reasonable to consider that the thoracocentesis on day 1 did not lead to complete removal of the air in the thorax for that dog leading to recurrent clinical signs or the dog might have had a slow continuous leak of air. However, the cause of the recurrent pneumothorax is not completely clear. In this case series, other than in 1 dog, thoracocentesis and/or placement of thoracostomy tubes appeared to lead to recovery from the pneumothorax without recurrence of clinical signs.

Five (41%) dogs developed CPA as a result of pneumothorax in this case series. This high incidence of CPA suggests that there is likely clinically important trauma to the tracheobronchial tree from the NG tube leading to a large volume of air in the thorax. It is also possible that the NG tube “seals the hole” in the tracheobronchial tree, and removal results in rapid pneumothorax. This seems to suggest that as soon as the NG tube is identified in the tracheobronchial tree, the veterinary professional should have the necessary supplies available to perform thoracocentesis prior to removal of the NG tube. While needle thoracocentesis is an effective way of evacuating the thorax, thoracostomy tubes may be more efficient due to their larger diameter (depending on the size of needle/catheter used for thoracocentesis), leading to a larger volume of air being removed faster, and they can provide opportunities for continuous suction. Small-bore wire-guided thoracostomy tubes placed using the modified Seldinger technique are atraumatic and well tolerated with few insertional and infectious complications.11 They are technically simple to place, do not require general anesthesia, have multiple fenestrations, and can be placed quickly in an emergency situation. In this case series, small-bore thoracostomy tubes were used in all cases for which thoracostomy tubes were placed. However, depending on the experience of the veterinarian, thoracostomy tubes may take longer to place, making them less efficient in a crisis, in which case a thoracocentesis should be performed to help stabilize the patient.

CPR also appears to have a high rate of success in these case series, with 3 of 3 dogs achieving ROSC after CPR, although one of them was euthanized due to the poor long-term prognosis of the underlying disease. Two out of the 3 dogs that underwent CPR were also successfully discharged. The high success rate is likely because pneumothorax is a reversible cause of CPA. It is important to highlight that CPR was carried out with concurrent thoracocentesis via a needle or thoracostomy tubes. The authors believe these dogs may not have survived if thoracocentesis had not been performed concurrently. The presence of a pneumothorax is an indication for open-chest CPR according to the Reassessment Campaign on Veterinary Resuscitation guidelines.12 None of the dogs in this study had open-chest CPR performed, as ROSC was obtained quickly after initiation of CPR. However, open-chest CPR should be considered for cases in which ROSC does not occur fast enough.

Most dogs in this case series had an NG tube placed using the standard technique. A novel technique of placement was described to minimize the incidence of NG tube misplacement by aspirating the tube to ensure negative pressure while the tube is in the thoracic inlet.7 Obtaining negative pressure should indicate the tube is in the esophagus and can be passed safely. It is important to note that 1 dog still had inadvertent placement of the NG tube despite use of the novel technique, indicating this technique is not infallible. It is possible that aspiration of the NG tubes may lead to collapse of the tube, which is a phenomenon described in human patients, giving an appearance of obtaining negative pressure while the tube is in the airway.13 It is also possible that the opening of the NG tube was lodged against the wall of the airway, giving the appearance of negative pressure. In addition, respiratory secretions may also occlude the tube, making aspirations falsely negative. In this case series, 4 dogs had negative pressure obtained after the tube was advanced to the level of the stomach, giving the appearance that the tubes were in the gastrointestinal tract, despite the fact that all 4 tubes were in the airway. In a prospective study in human patients, aspiration of the tube was unsuccessful in deciding whether the NG tube was in the airway about 53% of the time.14

Research in human patients has indicated that radiography remains the gold standard for NG tube verification, as other methods (including aspiration, auscultation, aspiration of gastric contents, submergence, capnography, and ultrasonography) all have limitations.15 The authors thus propose a modification to the novel technique as follows: the NG or NE tube should ideally be placed in the radiology suite (or the radiology suite should be available for tube check radiographs as soon as the tube is placed) and should be measured from the nose to the thoracic inlet, as well as from the nose to the last rib (or eighth or ninth rib for NE tubes). Once the tube is advanced to the thoracic inlet measurement, a lateral radiograph of the neck/larynx should be obtained to confirm the tube is in the esophagus before advancing the tube further. Fluoroscopy, where available, can also be utilized as a dynamic way of assessing tube position during placement verification.

It is also interesting to note that 2 dogs had an NG tube misplacement while endotracheally intubated and under general anesthesia. This is also similar to a previous case report in which 2 endotracheally intubated dogs suffered fatal complications of pneumothorax from NG tube placement.1 The endotracheal tube, instead of deflecting the feeding tube, may increase the risk of entry into the tracheobronchial tree by preventing glottic closure and inhibiting swallowing.2 It has been proposed that the stylet-stiffened fine bore feeding tube is able to squeeze past the low-pressure cuffs of the endotracheal tube. Hence the presence of an endotracheal tube does not prevent NG tube misplacement. In human patients, endotracheal intubation or tracheostomy is a risk factor for NG tube misplacement in the airway.16 This stresses the importance of obtaining tube placement radiographic images, even when the enteral feeding tube has been placed while the patient is endotracheally intubated. In addition, confirmation of feeding tube passage into the esophagus using a laryngoscope should be performed for intubated anesthetized patients.

The use of polyurethane tubes has evolved over time from earlier use of latex, silicone, or polyvinylchloride tubes.2 Polyurethane is soft, more flexible, and reduces the risk of penetration through the gastrointestinal tract.2 They are also better tolerated by patients.2 However, due to their greater flexibility, they also have an increased risk of misplacement.17 The NG tubes utilized by the institutions in this case series were all from 1 manufacturer (other than the polyvinyl red rubber tube). Both types of polyurethane tubes produced by this manufacturer were represented in this case series. The authors believe that there is only 1 major manufacturer represented in this case series as a result of that manufacturer dominating the veterinary enteral feeding tube market. The authors do not believe that this represents a problem with the tube itself but is rather an inherent risk of NG tube placement. The event rate of pneumothorax after misplacement of feeding tube in this study was very low (14/4,777 [0.3%]), so this was thought to be a rare complication. However, the incidence could have been higher due to the retrospective nature of the present study in which patients that developed pneumothorax secondary to a feeding tube placement may not have been identified.

The authors acknowledge that a much larger number of dogs likely had NG tubes placed in the tracheobronchial tree without developing pneumothorax. The NG tube misplacement is usually identified on thoracic radiography after the tube is placed, and the tube is then replaced without complication. The overall incidence of dogs with NG tube placement in the tracheobronchial tree could not be determined since many records did not reflect this complication (tubes are usually replaced in radiology without documentation in the medical records), but the authors believe only a small fraction of dogs that experience NG tube misplacement in the tracheobronchial tree ultimately go on to develop pneumothorax. The factors that contribute to the development of pneumothorax are currently undetermined. Considerations may include underlying lung disease (most dogs in this case series had healthy lungs), force of placing the feeding tube, patient cooperation, or skill of the individuals placing the tubes.

The median weight of dogs represented in this study was 7.4 kg (range, 1.87 to 28.2 kg; IQR, 10.6). While there were also large-breed dogs represented, it was interesting to note that smaller-sized dogs appeared to be overrepresented. The small sample size of the present study made it difficult to determine whether small-breed dogs are more likely to develop pneumothorax after NG tube placement, but an association with weight has not been identified in human patients.

It was also difficult to evaluate whether the development of pneumothorax was associated with the technical skills of the individual placing the NG tube, as specific information about who placed the NG tube was not documented in the medical records. As 3 of the 4 institutions in this case series are academic institutions, some of the tubes could have been placed by veterinary students or individuals with developing technical skills. However, some of the NG tubes in this case series were placed by veterinary professionals with many years of experience. This appears to suggest that NG tube misplacement may occur regardless of the technical proficiency of the operator, but additional investigation would be helpful.

All tubes represented in the present study were NG tubes, and no patient had an NE tube placed. The institutions represented in this study primarily place NG tubes, so NE tubes were rarely utilized in the patient population over the study period. While it is possible that NE tubes that are inadvertently introduced into the tracheobronchial tree do not make it past the trachea and are thus unlikely to cause a disruption of the smaller airways, NE tube placement should also be done with similar precautions as NG tubes.

In summary, NG tube misplacement into the tracheobronchial tree in this case series of dogs was most often associated with an almost immediate onset of respiratory distress secondary to pneumothorax. All patients undergoing feeding tube placement should be closely monitored for respiratory changes immediately following placement. Immediate intervention via thoracocentesis and/or placement of thoracostomy tubes is essential to the case management. Practitioners should consider placing NG/NE tubes in radiology or having the radiology suite ready for immediate radiograph procurement to identify misplacement of the tube while it is in the thoracic inlet. Confirmatory placement radiographs of the NG/NE tubes should include the neck/larynx or orthogonal views to help identify tracheobronchial intubation more easily. Finally, radiography or fluoroscopy should be considered the gold standard of verification of enteral tube placement before being used for administering nutrition or medications.

Although rare, life-threatening pneumothorax may develop secondary to NG tube placement in dogs. All dogs with NG feeding tubes placed should be monitored closely during and after the procedure. Radiographic images should be obtained after feeding tube placement as a standard of care. Immediate thoracocentesis with consideration for thoracostomy tube placement should be performed if pneumothorax is identified on radiography after feeding tube misplacement. ROSC occurred in 3 of 3 dogs that underwent CPR, likely due to the reversible nature of the arrest.

Supplementary Materials

Supplementary materials are posted online at the journal website: avmajournals.avma.org

Acknowledgments

No third-party funding or support was received. The authors have nothing to declare.

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    Johnson PA, Mann F, Dodam J, et al. Capnographic documentation of nasoesophageal and nasogastric feeding tube placement in dogs. J Vet Emerg Crit Care (San Antonio). 2002;12(4):227-233. doi:10.1046/j.1435-6935.2002.00042.x

    • Search Google Scholar
    • Export Citation
  • 5.

    Sparks DA, Chase DM, Coughlin LM, Perry E. Pulmonary complications of 9931 narrow-bore nasoenteric tubes during blind placement: a critical review. JPEN J Parenter Enteral Nutr. 2011;35(5):625-629. doi:10.1177/0148607111413898

    • Search Google Scholar
    • Export Citation
  • 6.

    Andresen EN, Frydland M, Usinger L. Deadly pressure pneumothorax after withdrawal of misplaced feeding tube: a case report. J Med Case Rep. 2016;10(1):30. doi:10.1186/s13256-016-0813-y

    • Search Google Scholar
    • Export Citation
  • 7.

    Herring JM. A novel placement technique for nasogastric and nasoesophageal tubes. J Vet Emerg Crit Care (San Antonio). 2016;26(4):593-597. doi:10.1111/vec.12474

    • Search Google Scholar
    • Export Citation
  • 8.

    Statistics online. Statistics Kingdom. Accessed September 1, 2022. https://statskingdom.com

  • 9.

    Ludwig LL. Surgical emergencies of the respiratory system. Vet Clin North Am Small Anim Pract. 2000;30(3):531-553, vi. doi:10.1016/S0195-5616(00)50038-2

    • Search Google Scholar
    • Export Citation
  • 10.

    King LG. Textbook of Respiratory Disease in Dogs and Cats. WB Saunders; 2004.

  • 11.

    Gilday C, Odunayo A, Hespel A-M. Spontaneous pneumothorax: management and prognosis. Top Companion Anim Med. 2021;45:100582. doi:10.1016/j.tcam.2021.100582

    • Search Google Scholar
    • Export Citation
  • 12.

    Fletcher DJ, Boller M, Brainard BM, et al.; American College of Veterinary Medicine. Veterinary Emergency and Critical Care Society. RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 7: clinical guidelines. J Vet Emerg Crit Care (San Antonio). 2012;22(suppl 1):S102-S131. doi:10.1111/j.1476-4431.2012.00757.x

    • Search Google Scholar
    • Export Citation
  • 13.

    Farrington M, Lang S, Cullen L, Stewart S. Nasogastric tube placement verification in pediatric and neonatal patients. Pediatr Nurs. 2009;35(1):17-24.

    • Search Google Scholar
    • Export Citation
  • 14.

    Kearns PJ, Donna C. A controlled comparison of traditional feeding tube verification methods to a bedside, electromagnetic technique. JPEN J Parenter Enteral Nutr. 2001;25(4):210-215. doi:10.1177/0148607101025004210

    • Search Google Scholar
    • Export Citation
  • 15.

    Irving SY, Lyman B, Northington L, Bartlett JA, Kemper C; Novel Project Work Group. Nasogastric tube placement and verification in children: review of the current literature. Crit Care Nurse. 2014;34(3):67-78. doi:10.4037/ccn2014606

    • Search Google Scholar
    • Export Citation
  • 16.

    Roubenoff R, Ravich WJ. Pneumothorax due to nasogastric feeding tubes. Report of four cases, review of the literature, and recommendations for prevention. Arch Intern Med. 1989;149(1):184-188. doi:10.1001/archinte.149.1.184

    • Search Google Scholar
    • Export Citation
  • 17.

    Hensel M, Marnitz R. Pneumothorax nach Anlage einer Magensonde: Darstellung eines Fallbeispiels und Literaturreview. Anaesthesist. 2010;59(3):229-232, 234. doi:10.1007/s00101-010-1683-0

    • Search Google Scholar
    • Export Citation
  • Figure 1

    Right lateral thoracic radiographic images immediately before (A) and after (B) correction of misplaced nasogastric (NG) tube in an anesthetized 9-year-old castrated male mixed-breed dog enrolled in a retrospective case series of 13 dogs with pneumothorax after NG feeding tube misplacement in the tracheobronchial tree between January 1, 2017, and July 31, 2022. A—The NG tube (star) and endotracheal tube (arrow) are seen along the plane of the trachea. B—The NG tube (star) has been repositioned within the plane of the esophagus, and there is severe pneumothorax (circle) with collapse of the lung lobes (triangle). This dog survived to hospital discharge.

  • Figure 2

    Right lateral thoracic radiographic images immediately before (A) and after (B) contrast administration in a 10-year-old spayed female Miniature Poodle in the study described in Figure 1. A—The NG tube (star) is seen along the plane of the trachea. B—The NG tube (star) remains within the plane of the trachea and contrast (oval) is administered through the misplaced tube into the pulmonary parenchyma. This dog did not survive to hospital discharge.

  • Figure 3

    Right lateral thoracic radiographic image of a 10-year-old female spayed mixed-breed dog in the study described in Figure 1. The NG tube (star) is seen along the plane of the trachea, leading to mild pneumothorax (rectangles) throughout the pleural space. Radiopaque circles over the cardiac silhouette are ECG pads. This dog did not survive to hospital discharge.

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    Rodriguez-Diaz J, Sumner JP, Miller M. Fatal complications of nasogastric tube misplacement in two dogs. J Am Anim Hosp Assoc. 2021;57(5):242-246. doi:10.5326/JAAHA-MS-7104

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    Pillai JB, Vegas A, Brister S. Thoracic complications of nasogastric tube: review of safe practice. Interact Cardiovasc Thorac Surg. 2005;4(5):429-433. doi:10.1510/icvts.2005.109488

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  • 3.

    Abood SK, Buffington CA. Improved nasogastric intubation technique for administration of nutritional support in dogs. J Am Vet Med Assoc. 1991;199(5):577-579.

    • Search Google Scholar
    • Export Citation
  • 4.

    Johnson PA, Mann F, Dodam J, et al. Capnographic documentation of nasoesophageal and nasogastric feeding tube placement in dogs. J Vet Emerg Crit Care (San Antonio). 2002;12(4):227-233. doi:10.1046/j.1435-6935.2002.00042.x

    • Search Google Scholar
    • Export Citation
  • 5.

    Sparks DA, Chase DM, Coughlin LM, Perry E. Pulmonary complications of 9931 narrow-bore nasoenteric tubes during blind placement: a critical review. JPEN J Parenter Enteral Nutr. 2011;35(5):625-629. doi:10.1177/0148607111413898

    • Search Google Scholar
    • Export Citation
  • 6.

    Andresen EN, Frydland M, Usinger L. Deadly pressure pneumothorax after withdrawal of misplaced feeding tube: a case report. J Med Case Rep. 2016;10(1):30. doi:10.1186/s13256-016-0813-y

    • Search Google Scholar
    • Export Citation
  • 7.

    Herring JM. A novel placement technique for nasogastric and nasoesophageal tubes. J Vet Emerg Crit Care (San Antonio). 2016;26(4):593-597. doi:10.1111/vec.12474

    • Search Google Scholar
    • Export Citation
  • 8.

    Statistics online. Statistics Kingdom. Accessed September 1, 2022. https://statskingdom.com

  • 9.

    Ludwig LL. Surgical emergencies of the respiratory system. Vet Clin North Am Small Anim Pract. 2000;30(3):531-553, vi. doi:10.1016/S0195-5616(00)50038-2

    • Search Google Scholar
    • Export Citation
  • 10.

    King LG. Textbook of Respiratory Disease in Dogs and Cats. WB Saunders; 2004.

  • 11.

    Gilday C, Odunayo A, Hespel A-M. Spontaneous pneumothorax: management and prognosis. Top Companion Anim Med. 2021;45:100582. doi:10.1016/j.tcam.2021.100582

    • Search Google Scholar
    • Export Citation
  • 12.

    Fletcher DJ, Boller M, Brainard BM, et al.; American College of Veterinary Medicine. Veterinary Emergency and Critical Care Society. RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 7: clinical guidelines. J Vet Emerg Crit Care (San Antonio). 2012;22(suppl 1):S102-S131. doi:10.1111/j.1476-4431.2012.00757.x

    • Search Google Scholar
    • Export Citation
  • 13.

    Farrington M, Lang S, Cullen L, Stewart S. Nasogastric tube placement verification in pediatric and neonatal patients. Pediatr Nurs. 2009;35(1):17-24.

    • Search Google Scholar
    • Export Citation
  • 14.

    Kearns PJ, Donna C. A controlled comparison of traditional feeding tube verification methods to a bedside, electromagnetic technique. JPEN J Parenter Enteral Nutr. 2001;25(4):210-215. doi:10.1177/0148607101025004210

    • Search Google Scholar
    • Export Citation
  • 15.

    Irving SY, Lyman B, Northington L, Bartlett JA, Kemper C; Novel Project Work Group. Nasogastric tube placement and verification in children: review of the current literature. Crit Care Nurse. 2014;34(3):67-78. doi:10.4037/ccn2014606

    • Search Google Scholar
    • Export Citation
  • 16.

    Roubenoff R, Ravich WJ. Pneumothorax due to nasogastric feeding tubes. Report of four cases, review of the literature, and recommendations for prevention. Arch Intern Med. 1989;149(1):184-188. doi:10.1001/archinte.149.1.184

    • Search Google Scholar
    • Export Citation
  • 17.

    Hensel M, Marnitz R. Pneumothorax nach Anlage einer Magensonde: Darstellung eines Fallbeispiels und Literaturreview. Anaesthesist. 2010;59(3):229-232, 234. doi:10.1007/s00101-010-1683-0

    • Search Google Scholar
    • Export Citation

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