Madam,
We often face difficulty in insertion of nasogastric tube (NGT) especially in the head and neck cancer patients due to restricted mouth opening, intraoral growth, and distorted anatomy. Its correct placement can be confirmed by auscultation, aspiration of bilious fluid, radiologically, and intraoperatively by palpating the NGT in the stomach. But still the malposition of NGT is frequently reported (2%) and may lead to hypoxia, injury, aspiration, and even mortality if not detected well in time.[1,2]
Two adult male carcinoma buccal mucosa patients with restricted mouth openings were posted for commando surgery. They were intubated nasally with awake fiberoptic intubation after airway topicalization. The correct placement of endotracheal tube (ETT) was confirmed with square wave capnography and controlled mechanical ventilation was initiated with fresh gas flows (FGFs) of 6 L/min using closed circuit. A number 12 French gauge NGT was inserted post intubation in both the cases with minimal resistance. But, auscultation of the epigastrium for air to confirm its placement was inconclusive. Direct laryngoscopy was not feasible due to restricted mouth opening and portable X-ray machine was not available on the operation theatre floor. We attached suction to the NGT but no gastric contents could be aspirated and instead to our surprise the ventilator bellows collapsed immediately. After the NGT suction was disconnected the ventilator started functioning normally. Thereafter, the open end of NGT was inserted into a water seal, showed the gas bubbles escaping cyclically with expiration.
We inserted a 4 mm fiberoptic bronchoscope (FOB) alongside the NGT and were surprised to find the NGT in the trachea. The soft NGT might have followed the curve of the 7 mm ID nasal ETT and entered the trachea. Smaller NGT (12F) and high FGFs (6 L), masked “the circuit leak” due to misplaced NGT. When the suction was applied, the leak became significant enough to cause the bellows to collapse. Air leak following NGT insertion has been previously reported, but suctioning the NGT leading to ventilator bellows collapse to rule out intratracheal malposition has not been described.[3]
Insertion of NGT is a simple procedure and mostly uneventful. Complications due to misplacement of the NGT into the trachea and lungs may occur in 2% of cases.[4] An undetected misplaced NGT may lead to tracheobronchial injury, pleural effusion, and pneumonitis.[5] The National Patient Safety Agency has a record of 41 Never Events (reported between 2009 and 2010) of undetected misplaced NGT prior to use leading to harm or mortality.[5]
In our case, the use of a smaller bore NGT (for better postoperative tolerance), a smaller lumen ETT (size 7 mm ID) for nasotracheal intubation and possibly inadequately inflated ETT cuff, facilitated the tracheal passage of the NGT.
Routine confirmation by auscultation may be inaccurate in upto 20% of cases.[6] Other confirmatory tests like auscultation, dyspnea, altered speech, cough, air bubbles on exhalation, NGT aspirate pH, capnography, and ultrasonography have been described, but are not fool proof and have their limitations.[7] Laryngoscopy is a feasible option for anesthetists but it was not possible in our patients due to the restricted mouth opening. X-ray is considered confirmatory but may not be readily available at all the locations.
We have tried this simple test of confirming malposition by applying suction to the open end of the NGT on many occasions later and found it to be useful consistently. Notably, the test may turn out to be false negative if the patient is being ventilated with very high gas flows which may preclude the collapse of bellows even after application of suction. It is a simple and quick test that can be utilized to confirm tracheal malposition of NGT in intubated patients. However, further studies are required to validate its routine clinical application.
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References
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