Department of Anaesthesiology, Jichi Medical School, Minamikawachi-machi, Tochigi, 3290498, Japan*Corresponding author
Accepted for publication: May 24, 2002
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Abstract |
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Br J Anaesth 2002; 89: 6413
Keywords: airway, obstruction; anaesthetics i.v., propofol; complications, learning difficulties; complications, respiratory; intubation, tracheal; ventilation, high frequency jet
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Introduction |
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We describe a patient with learning difficulties who had severe airway obstruction secondary to a large tracheal tumour at the carina. In this case, spontaneous breathing during general anaesthetic, combined with high frequency jet ventilation (HFJV), was effective and facilitated the successful resection of the tumour through a tracheal tube.
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Case report |
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Prior to induction of anaesthesia, we prepared a jet ventilation catheter, and tracheostomy instruments in case of complications. The patient inhaled oxygen 100% for 10 min whilst in the left lateral decubitus position and was then turned to the supine position. Anaesthesia was induced with propofol 200 mg and manual ventilation via a facemask was started. Physical examination suggested a reduction in right chest wall movement at this time and the SpO2 fell from 100 to 95%. Succinylcholine 140 mg was administered to facilitate orotracheal intubation with a cuffed tube (internal diameter, 8.5 mm). The lungs were ventilated through the tracheal tube using a high frequency jet ventilator (driving pressure, 1.0 kgf cm2; I/E ratio, 0.33; rate, 60120 min1; FIO2, 0.31.0). Bilateral chest wall movement was restored after spontaneous breathing had resumed. We decided to allow the patient to continue to breathe spontaneously. Anaesthesia was maintained with propofol 6 mg kg1 h1 and buprenorphine 0.2 mg intravenously.
Prior to the bronchoscopic procedure, the trachea was topically anaesthetized with lidocaine 2% (total dose, 400 mg) via the tracheal tube. The operation was performed with a fibreoptic bronchoscope (external diameter, 6 mm) via the tracheal tube. HFJV was then performed through a 10-Fr suction catheter, which was passed through the same tracheal tube for 2 cm into the left main bronchus. Whenever the SpO2 fell below 95%, the bronchoscopic procedure was temporarily halted and ventilation was gently assisted. This occurred three times during HFJV. As the SpO2 also fell if the driving pressure was reduced, we set the driving pressure at 1.0 kgf cm2. As a result, the SpO2 did not then fall below 93% at any stage. Arterial blood pressure remained at 100120/4560 mm Hg whilst the heart rate was between 80 and 100 beats min1. There were no ECG changes throughout the procedure. Arterial blood gas analysis revealed a PaO2 of 10.8 kPa, a PaCO2 of 7.8 kPa and a pH of 7.31 when the SpO2 fell to its lowest value of 93% during the operation.
The stalk of the tumour was cauterized. The surgeons then removed the tumour, together with the tracheal tube, using a basket catheter because the tumour was too large to pass through the tracheal tube. Following successful removal of the tumour and the tracheal tube, the patient developed laryngospasm. Vecuronium bromide 10 mg and hydrocortisone sodium succinate 500 mg were administered intravenously and another tracheal tube (internal diameter, 7.5 mm) was inserted. The surgeons confirmed complete resection of the tumour by fibreoptic bronchoscopy. Chest wall movement was symmetrical soon after the operation had been completed and the lungs were artificially ventilated for a further 30 min. The second tracheal tube was removed following administration of neostigmine 2.5 mg and atropine 1.0 mg to antagonize any residual neuromuscular block. The operation lasted 70 min. The total durations of anaesthesia and HFJV were 150 min and 53 min, respectively. The patient developed no further airway problems following the surgery.
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Discussion |
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The second challenge of the case related to the method of ventilation used during the bronchoscopic procedure. Spontaneous breathing has frequently been recommended during anaesthesia in such circumstances, to avoid airway obstruction resulting from muscle paralysis or positive pressure ventilation.2 In our patient, we noted that movement of the right chest wall worsened during positive pressure ventilation on induction of anaesthesia. It was thought that right main bronchus obstruction had been induced by the artificial ventilation, resulting in dynamic hyperinflation. We therefore allowed spontaneous breathing during surgery and applied HFJV in order to assist ventilation effectively.2 The disadvantages of this technique can include ineffective ventilation and a potential hindrance to surgery. Bronchoscopy indicated that the spherical tumour almost completely blocked the right main bronchus and so the HFJV catheter was passed about 2 cm into the left main bronchus. In this way, we were able to prevent hyperinflation of the right lung and allow optimal access to the surgical field.
The other method of managing hypoxaemia during one-lung ventilation is continuous positive airway pressure (CPAP). However, it has been reported that CPAP does not generate sufficient alveolar oxygen tension in the non-ventilated lung to prevent hypoxaemia in patients with bronchial obstruction.3 Studies by Slinger and colleagues4 5 reported that the side of the ventilated lung was an important factor in this respect; the efficiency of oxygenation and of gas exchange was better when the right lung rather than the left lung was ventilated during one-lung ventilation. Although in this case only the left lung was ventilated, we were able to use HFJV with a 10-Fr suction catheter and a FIO2 of only 0.3 during the procedure. The effects of HFJV on oxygenation and gas exchange were not determined since neither the flux nor the pressure were measured. However, we considered that HFJV supported breathing effectively and did not hinder spontaneous breathing in this case.
Heliumoxygen mixtures are commercially available and may be useful in the emergency department to treat patients with airway obstruction.6 7 Breathing a mixture of helium and oxygen leads to a reduction in the resistance to flow within the airways, and consequently results in a decrease in the work involved in breathing. Whether awake or asleep, our patient showed a deterioration in his condition when his position was changed. Although helium would have been potentially useful, it is not available for such treatment in Japan. It might have been an excellent method of allowing spontaneous breathing in combination with HFJV.
The third aspect of this case for consideration was the anaesthetic agents used. Anaesthetic induction with inhalational agents is usually regarded as the technique of choice in view of its safety.2 Nevertheless, adverse events have been reported with this technique.8 Using the i.v. anaesthetic agent, propofol, we were able to maintain the depth of anaesthesia more readily than with inhaled anaesthetic agents. It has been reported that the respiratory depressant effects of propofol 6 mg kg1 h1 are clinically acceptable and we selected an i.v. anaesthetic technique for these reasons.9
We applied topical anaesthetic to the trachea and bronchus in order to prevent adverse reflexes during the fibreoptic bronchoscopy. The surgeons removed the tumour with the tracheal tube, contrary to our expectations. Unfortunately, the larynx had been insufficiently anaesthetized to prevent laryngospasm after extubation.
In summary, this case report describes the anaesthetic management of a patient with learning difficulties who successfully underwent bronchoscopic resection of a large tracheal tumour. During the procedure, i.v. anaesthesia with propofol and spontaneous breathing, combined with HFJV, allowed effective management of the airway.
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References |
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