Pneumothorax from intrapleural placement of a nasogastric tube.
Nasogastric tube insertion is a commonly performed procedure that can be associated with significant morbidity and even mortality. There is no universally accepted technique to confirm correct placement. Most confirmatory methods are performed after placement, therefore misplacement and potential complications may have already occurred. We report a case where a commonly used bedside confirmatory test gave false reassurance that the nasogastric tube was properly positioned, but a plain chest X-ray revealed a massive pneumothorax due to inadvertent intrapleural placement of the tube. Due to the deficiencies of traditional confirmatory bedside techniques, and the limitations of modern and more sophisticated confirmatory methods, theplain chestX-ray remains the gold standard test to confirm correct nasogastdc tube placement. We appraise the methods commonly employed to confirm nasogastdc tube placement, and discuss factors that may increase the risk of misplacement.
Key Words: nasogastric tube, complications, intrapulmonary placement, pneumothorax
Nasogastric tubes (NGT) are placed in hundreds of thousands of hospitalized patients every year (1). They are an integral part of the management of many medical and surgical conditions. Indications for their use can be diagnostic (monitoring of mucosal gastric pH, confirmation of gastrointestinal bleeding), therapeutic (removal of toxins, decompression of acute bowel obstruction, administration of materials such as medication, enteral nutrition, contrast or charcoal) or prophylactic (decompression of stomach prior to abdominal surgery). The complication rate of NGT use ranges between 0.3% and 15% (2-4). Complications can be associated with significant morbidity and even mortality and can occur during insertion, whilst in situ, or during removal (Table 1). The purpose of confirming correct placement is to prevent complications from occurring and to avoid the introduction of enteral feeds and medication into the lungs. Most confirmatory placement techniques however are performed after placement, therefore misplacement and potential complications may have already occurred. We report such a case, where a commonly used bedside confirmatory test gave false reassurance that the NGT was properly positioned, but a plain chest X-ray revealed a massive pneumothorax due to inadvertent intrapleural placement of the tube. We appraise the traditional bedside techniques that are used to confirm NGT placement, and discuss the limitations of modern and more sophisticated confirmatory methods. The factors that may increase the risk of nasogastric tube misplacement are outlined.
A 42-year-old woman presented to hospital with hypoxaemic respiratory failure secondary to a severe community-acquired pneumonia. The chest X-ray demonstrated right upper lobe consolidation and extensive bilateral alveolar infiltrates. Initial management included oxygen therapy, empirical intravenous antibiotic therapy, bronchoscopy and physiotherapy for sputum retention. The patient became more restless and tachypnoeic, with increasing oxygen requirements. She required emergency endotracheal intubation for further respiratory support and her condition stabilized with controlled positive pressure ventilation. An NGT was easily inserted for gastric decompression, drug administration, and enteral nutrition. Gastric contents were not able to be aspirated, but insufflations of air and auscultation over the epigastric area revealed an obvious 'pseudo-confirmatory gurgle' that suggested correct placement. However the chest X-ray revealed the NGT within the trachea and entering the left lower bronchus with the tip of the catheter in the left basal pleural space (Figure 1). On removal of the NGT, the ventilatory peak airway pressures increased and the patient became tachycardic and hypoxic despite 100% oxygen administration. Auscultation of the chest revealed hyperresonance with decreased expansion and breath sounds over the left side with no audible wheeze. There was no haemodynamic compromise. An urgent repeat chest X-ray confirmed a large left pneumothorax, secondary to the NGT penetrating the left basal pleural space. There was no mediastinal displacement or pneumomediastinum (Figure 2). A large-bore tube thoracostomy was performed. There was subsequent improvement of gas exchange and peak airway ventilatory pressures.
Although many authorities advocate the plain chest X-ray as the gold standard test to confirm correct NGT placement, there is no universally accepted or practised technique. Due to cost and time factors (especially at night) in confirming NGT placement with portable radiographs, many institutions still rely on traditional bedside tests. These methods include air insufflations and auscultation over the epigastric area, aspiration of gastric fluid with assessment of the visual and chemical characteristics of the aspirate, and the ability of the patient to phonate (5-9). Compared to the plain chest X-ray, these bedside techniques lack specificity and sensitivity and often give false reassurance that the NGT is properly positioned. Insufflations with 20 to 50 ml of air and auscultation over the epigastric area for 'bubbling, gurgling, or a whooshing sound' may be unreliable with small tubes, especially those with a guidewire because of reduced air flow. Transmitted sounds from air bubbling in a bronchus, oesophagus or pleural space, and even normal bowel sounds can be misinterpreted as correct placements. Aspiration of gastric contents may not be possible through small-bore tubes or if the stomach is empty. Pleural fluid aspirated through a malpositioned tube may be also mistaken for gastric contents (10). A combination of pH measurement and assessment of gastric secretions is a simple, accurate, and economical bedside method to evaluate correct gastric placement (11). Normal gastric aspirate colour is clear to slightly yellow, but may be altered in patients with gastrointestinal bleeding or bowel obstruction. Normal gastric pH is 1 to 5; aspirates from the small intestine have a pH level of 7 or higher, and pH can be even higher in samples from the lung. However, pH levels as low as 6 can be found from respiratory aspirates, and conversely, gastric aspirates can have pH levels above 6. Patients taking H2 receptor blockers or proton pump inhibitors, as well as patients with illnesses such as pernicious anaemia, will also have higher gastric pH concentrations. Therefore, the pH method can lead to inconclusive results and is not always reliable in confirming gastric placement (11). Immersing the end of the NGT in water and checking for bubbling, listening over the end of the nasogastric tube for breath sounds, and checking for the misting of the inside of the tube during patient expiration, are other less reliable methods used to confirm NGT misplacement.
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Due to the deficiencies of these traditional bedside tests, modern and more sophisticated methods have been proposed. These include endoscopy, fluoroscopy, bedside videoscopic placement, electrocardiogramguided placement, end-tidal capnography and capnometry (1,4,5.12-14). These methods can be expensive and time-consuming, difficult to interpret, and may also be associated with significant complications (1,15). They also may be impractical should the patient require transporting to the radiology unit. End-tidal C[O.sub.2] measurements have been shown to be a simple, noninvasive, very sensitive, and cost-effective method of assuring accurate tube placement in mechanically ventilated patients (13). Although accurate interpretation of the capnogram requires sophisticated knowledge, the ability to recognize the presence or absence of a waveform is all that is required for accurate assessment of inadvertent intrapulmonary placement using this method. The disposable capnometer is a simple, portable device that produces a colour change in the presence of exhaled C[O.sub.2]. It negates the need for respiratory technicians, anaesthetists, or critical care physicians to set the capnogram. Although capnography and capnometry are very sensitive techniques in confirming tracheal and intrapulmonary NGT placement, they do not ensure accurate placement of the NGT in the stomach or duodenum. Coiling of the nasogastric tube in the oesophagus or oesophageal perforation are examples where these methods would be of limited use in confirming NGT malposition.
The clinician must always be cognisant of other predisposing factors that may increase the risk of NGT misplacement. These factors may be related to the patient, the technique of insertion, or the actual design of the NGT (Table 2). Critically ill patients are at particular risk due the presence of an endotracheal tube or tracheostomy, a decreased level of consciousness with obtunded airway reflexes, and the inability to report chest discomfort or dyspnoea after tube insertion (5). Due to the limitations of the traditional methods for checking NGT placement, the plain chest X-ray should therefore remain the gold standard confirmatory test in this setting. In patients with increased risk factors for NGT misplacement (Table 2), placement of the NGT may be technically difficult. In these situations, the NGT should be sited if possible under direct vision, by an experienced operator, with adequate lubricant, and patient position should be optimized to facilitate the most advantageous placement technique (fully sitting if awake, supine with mild neck flexion if unconscious). If any resistance is encountered during placement, the tube should be withdrawn immediately and repositioned. The use of flexible polymer fine bore tubes, e.g. silastic products, are more likely to coil in the oropharynx or upper oesophagus, and are more difficult to aspirate, particularly if a wire stiffener is used to facilitate placement. Whilst the presence of a stiffening wire or stiff monofilament core can facilitate passage of the tube into the duodenum, it can also increase the risk of injury to the pharynx, larynx, gastrointestinal tract and tracheobronchial tree (10). Once the wire is removed, it should never be reinserted. A radio-opaque marker along the length of the tube will enable visualization of the anatomical course on plain X-ray and identify suboptimal placement.
This case emphasises the importance of obtaining a chest X-ray to determine the position of a NGT after its insertion. Insufflating air through the tube whilst auscultating the abdomen, and aspirating the tube for gastric secretions are inadequate methods to determine correct NGT placement. In this case, the pseudo-confirmatory sound was transmitted from air insufflated into the left pleural space, which lies in close proximity to the epigastric area. In summary, a high index of suspicion for potential complications is needed when inserting and confirming correct placement of the NGT The limitations of the traditional bedside confirmatory methods must always be borne in mind. The chest X-ray should remain the gold standard method to confirming NGT placement, especially for critically ill patients who are at increased risk of intrapulmonary misplacement due to obtunded airway reflexes, decreased consciousness levels and the presence of an endotracheal tube or tracheostomy.
Accepted for publication on November 11, 2005.
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L. WEINBERG *, D. SKEWES ([dagger])
Department of Anaesthesia, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia
* B.Sc., M.B., B.Ch., M.R.C.P, Anaesthetic Registrar, Department of Anaesthesia, Peter MacCallum Cancer Institute, East Melbourne, Victoria.
([dagger]) M.B., B.S., ER.C.A., Director of Anaesthesia & Critical Care, Department of Anaesthesia, Peter MacCallum Cancer Institute, St Andrews Place, East Melbourne, Victoria.
Address for reprints: Dr Laurence Weinberg, Department of Anaesthesia, Austin Health, PO Box 5555, Heidelberg, Victoria 3034.
TABLE 1 The complications of nasogastric tubes Nasopharyngeal -- haemorrhage, ulceration, oropharyngeal coiling, eustachian tube misplacement Larynx/vocal cords -- trauma, ulceration, vocal cord dysfunction, vocal cord paralysis Oesophageal -- coiling, haemorrhage, ulceration, perforation, tracheo-oesophageal fistula Pleuropulmonary -- aspiration of gastric contents/enteral feed: pneumonitis, pneumonia, empyema, sepsis -- bronchial misplacement: atelectasis, collapse, pulmonary haemorrhage, perforation -- intrapleural misplacement: pneumothorax, haemothorax, hydrothorax, bronchopleural fistula -- airway obstruction (early or late onset): respiratory distress, ventilatory failure Gastrointestinal -- haemorrhage, ulceration, pneumoperitoneum, perforation, peritonitis, sepsis Mediastinal -- mediastinal misplacement, mediastinitis, pneumomediastinum Other -- nasogastric tube syndrome (odynophagia, vocal cord paralysis, acute or delayed airway obstruction) -- intracranial misplacement TABLE 2 Factors increasing the risk of nasogastric misplacement/complications Nasogastric Patient factors Technique factors tube factors altered mental status inexperienced operator fine bore depressed conscious incorrect patient stiff monofilament state position core critically ill blind insertion stiffening wire patients endotracheal tube incorrect NGT length absent radio opaque marker tracheostomy insufficient flexible polymer lubrication construction nasopharyngeal pathology oesophageal pathology anatomical facial abnormalities facial trauma/ inhalation injury upper airway/ oesophageal surgery anticoagulation/ thrombophilia
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|Title Annotation:||Case Report|
|Author:||Weinberg, L.; Skewes, D.|
|Publication:||Anaesthesia and Intensive Care|
|Date:||Apr 1, 2006|
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