EDITOR:
Ventilatory problems during surgery in the prone position may be a serious complication [Reference Santos, Oliveira and Ferreira1]. We report an incident where there was dissection of a reinforced endotracheal tube that led to its partial obstruction. This case shows an unexpected complication from reusing products intended for single use.
A 62-yr-old female (weight 68 kg) who was scheduled for total laminectomy with posterior lumbar fusion for lumbar stenosis was intubated with a 7.0-mm reinforced endotracheal tube (Safety-flex; Mallinckrodt®, Athlon, Ireland). Her lungs were ventilated with a mixture of sevoflurane 1.5 MAC (minimum alveolar concentration) in oxygen (35%) and nitrous oxide (65%). Her peak airway pressure (Ppeak) was 25 cmH2O and end-tidal CO2 (etCO2) was 36 mmHg at the beginning of anaesthesia without wheezing. Ppeak increased to 30 cmH2O and etCO2 to 40 mmHg in the prone position. Approximately 30 min after prone positioning, Ppeak increased to 40 cmH2O and etCO2 increased to 45 mmHg. We could not pass a suction catheter beyond a distance of 24 cm from the entrance of the tracheal tube. Using a fibrescope, we could see the appearance of a meniscus and a crescent shape on the inner wall. Because of the prone position, we could not change the tube but managed to maintain ventilation, saturation and etCO2 within the normal range by a change of ventilatory mode for the remaining 5 h of the procedure. After returning to the supine position at the end of the operation, we extubated the patient and her self-respiration was good. Unfortunately, we found mild left lower lobe atelectasis postoperatively, which responded to physiotherapy. Her lung condition had returned to normal without complication by the second postoperative day.
Examination of the reinforced tube showed two internal blisters, one at the entrance and one at 24 cm from the entrance. Examination using a rigid fiberscope and computed tomography (Fig. 1) showed a dissection of the inner layer of the tube. The dissection had caused longitudinal blisters of 2.8 and 4.2 cm length and reduction of the internal diameter to 3.5 and 2.9 mm at the proximal and distal parts, respectively.
Figure 1 Computed tomographic picture and fibrescopic view of the inside of the endotracheal tube. (a–c) distal part and (d–f) proximal part. Arrows indicate the area of dissection.
We assumed that the damage of the tube was caused by faulty manufacture. However, we subsequently discovered that the cause was multiple re-use of the single-use tube. Similar complications have been reported during anaesthesia with use of N2O [Reference Populaire, Robard and Souron2,Reference Kopp and Wehmer3] or even without N2O [Reference Tose, Kubota, Hirota, Sakai, Ishihara and Matsuki4], exposure of heat, ethylene oxide [Reference Tose, Kubota, Hirota, Sakai, Ishihara and Matsuki4–Reference Rao, Ali, Ramkiran and Chandrasekhar6] and gluteraldehyde solution [Reference Rao, Ali, Ramkiran and Chandrasekhar6] and stretching of a reinforced endotracheal tube [Reference Rao, Ali, Ramkiran and Chandrasekhar6]. The tube in this case had been cleaned after each use with hypochlorous acid (Medilox solution; Hicro-S®, Soosan GIC Co Ltd, Seoul, Korea) after ultrasonic cleansing for 30 min. We should bear in mind that repeated reuse of reinforced endotracheal tubes that are designed for single use is unwise.
