BJA Advance Access originally published online on September 15, 2008
British Journal of Anaesthesia 2008 101(5):690-693; doi:10.1093/bja/aen264
Placing the tip of the endotracheal tube at the carina and passing the endobronchial blocker through the Murphy eye may reduce the risk of blocker retrograde dislodgement during one-lung anaesthesia in small children
1 Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong SAR, People's Republic of China
2 Department of Anaesthesiology, Queen Mary Hospital, Hong Kong SAR, People's Republic of China
* Corresponding author. E-mail: hoamh{at}yahoo.com
Accepted for publication July 17, 2008.
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Abstract |
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We present nine cases of one-lung anaesthesia in small children and infants in which a novel technique was used to reduce the risk of endobronchial blocker retrograde dislodgement. The technique involved threading the stem of the blocker through the Murphy eye of the endotracheal tube (ETT) and deliberately passing the tip of the ETT all the way to the carina. The tip of the ETT blocked any retrograde movement of the blocker.
Keywords: anaesthesia, paediatric; equipment, tubes endobronchial blocker; surgery, thoracic; ventilation, one-lung
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Introduction |
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In minimally invasive thoracic surgery, which has in recent years been increasingly used in children, including newborns, the anaesthetist may be requested to provide effective one-lung anaesthesia (OLA). Unfortunately, lung isolation in very small children is particularly difficult as double-lumen tubes (DLTs) and endotracheal tubes (ETT) with built-in endobronchial blockers (EB) (e.g. Univent tube®) are not available for children <6–10 yr of age. These devices cannot be made small enough for smaller children and newborns as the lumens would become too narrow for effective ventilation, toiletry, manipulation, and the passage of paediatric fibreoptic bronchoscopes. As such, the principal technique for OLA in small children and newborns is the use of a standard ETT with a separate EB.1–3 This technique is challenging to apply in adults but particularly so in very small children. When a separate balloon-tipped catheter is used to block a mainstem bronchus, there is a tendency for the EB to dislodge back into the trachea1–6 causing tracheal obstruction, loss of lung isolation, interruption of surgery, and increased surgical manipulation of the lung. Even with the Arndt 5F high-volume low-pressure paediatric EB, retrograde dislodgement into the tracheal lumen occurred in three of 23 (13%) cases in one series.2 We believe that in less experienced hands, this problem may occur even more frequently. Failure of lung isolation may necessitate the surgeon to convert from a minimally invasive to an open approach to cope with the now ventilated lung. In small children, open thoracotomy not only leads to more postoperative pain and a big scar, but also to late complications such as ‘winged’ scapula (incidence: 24%), marked asymmetry of the thoracic wall (20%), fusion of the ribs (10%), severe scoliosis (8%), and breast maldevelopment (3.3%).7 Because of their short mainstem bronchi, small children may be particularly susceptible to this EB retrograde dislodgement problem. We present a novel technique of stabilizing the EB in the endobronchial position in small children.
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Case series |
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We hypothesized that retrograde-migration of the EB can be prevented by placing the tip of the ETT at the carina. In order to prevent the EB from blocking the ETT tube, the EB can be deflected and anchored by passing its stem through the Murphy eye. Ethics approval for the investigation was obtained from the Chinese University of Hong Kong-New Territories Eastern Cluster Ethics Review Board. Children whose OLA required an EB technique because they were too small for the smallest available DLT or Univent® tube were eligible. Cases requiring a 2.5 mm ID ETT were excluded as passage of our paediatric fibrescope (external diameter 1.8 mm) would not be possible. Informed written consent was obtained from a parent or guardian.
The arrangement of the EB with respect to the ETT (extra- or intra-luminal) was determined by the diameter of the ETT. ETTs with ID 
4.5 mm could accommodate an EB [Fogarty or Arndt 5F (Cook Incorporated, Bloomington, IN, USA)] and a 1.8 mm fibrescope (Olympus LF, Tokyo, Japan) within its lumen simultaneously. ETTs with ID <4.5 mm required that the EB be extra-luminal.
When the EB catheter was within the ETT lumen, preparation for intubation was as follows: the EB was placed through the Murphy eye (Fig. 1A) such that when inflated, the EB balloon was just distal to the ETT tip (Fig. 1B). Next, the ETT–EB unit was assembled with an Arndt Multiport Adapter and with the balloon catheter stem tightly locked in place with the Tuohy-Borst type valve8 at the catheter port before intubation. When the EB catheter was outside the ETT lumen, preparation for intubation was as follows: the ETT bevel was trimmed to reduce airflow resistance (Fig. 1C and D). The lightly lubricated EB was threaded through the Murphy eye and its tip slightly bent to facilitate endobronchial intubation (Fig. 1C). When inflated, the EB balloon should be just distal to the ETT tip (Fig. 1D).
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Non-invasive arterial pressure, ECG, pulse oximeter (SpO2) were applied in all cases. Anaesthesia was induced with sevoflurane or thiopental. Except for tracheo-oesophageal fistula (TOF) repair, intubation was facilitated with atracurium. TOF patients received lidocaine spray of the airway. Maintenance was with isoflurane, atracurium, and fentanyl.
Orientation of the ETT–EB unit was important during intubation. When the EB was mainly intraluminal in the ETT (Fig. 1A and B), the ETT–EB unit, having passed the larynx, was advanced with the deflated balloon pointing towards the target bronchus. If the EB catheter was mainly outside the ETT (Fig. 1C and D), the ETT bevel was oriented to face the ventilated lung, whereas the EB was slightly bent to face the target mainstem bronchus. With either technique, the ETT was advanced until its tip almost abutted the carina, meaning that further advancement would result in loss of equal bilateral air entry on auscultation during bilateral ventilation, and high ventilatory pressures during OLA (Fig. 2A and B and see Supplementary material online, Fig. 2 and 3).
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To effect leak-free ventilation during fibrescope-assisted EB placement using the Arndt Multiport Adapter, a reducer for minimal invasive surgery with a 2/3-mm pinhole (Mini Step, InnerDyne, Salt Lake City, UT, USA) was used at the fibrescope port.9
ETT and EB positions and EB inflation were checked with a stethoscope and a fibrescope immediately after intubation and after positioning of the patient. The ETT and EB were secured at the mouth. Collapse of the blocked lung was achieved by first opening the ETT to atmospheric pressure for several seconds, followed by EB inflation. Further adjustment of EB inflation volume was made as necessary during the cases. Resumption of bilateral ventilation towards the end of surgery was effected with deflation of the EB balloon. For patients requiring tracheal intubation after operation, the EB was completely removed and the ETT tip withdrawn to mid-tracheal level.
We used this technique on nine occasions for eight patients (Table 1). In seven cases (1–4, 7–9), the EB was inside the lumen of the ETT. In Cases 5 and 6, the children were too small so the EB was extra-luminal.
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None of the patients had difficult laryngoscopic view. The ETT–EB unit passed through the larynx easily in all cases. When the Arndt 5F EB was used, there was no need for the wire loop to be attached to the fiberscope before intubation.8 In all cases, the EB slid easily into the chosen bronchus. The impression was that ETT and EB placement with this technique took less time than the standard technique of intubating with the ETT and EB as two separate entities.
Lung isolation was achieved in all nine cases. Retrograde migration or excessive EB herniation into the tracheal lumen did not occur in any of the cases and reposition was not required. The surgeons reported good to excellent working condition in all cases. When bilateral ventilation was resumed, the deflated EB was easily and completely removed from the patient and the ETT tip was withdrawn back to approximately mid-tracheal level in all cases.
No fibreoptic assessment of the tracheobronchial tree was done at the end of each case. During EB placement in Case 1b, the tracheobronchial tree appeared normal without any evidence of injury sustained during surgery 2 months earlier (Case 1a).
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Discussion |
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We have described our preliminary experience with a novel technique for preventing dislodgement of an EB during OLA into the trachea in small children.1 2 Retrograde dislodgement of the EB into the trachea leads to loss of lung isolation and airway obstruction. Intraoperative EB repositioning can be extremely cumbersome and frustrating. If the problem recurs, surgical time and lung trauma may increase. If failure to collapse a lung leads to conversion to an open thoracotomy, increased postoperative pain and long-term thoracic deformity may result.7 By deliberately placing the ETT tip at the carina and with the EB anchored and deflected by the Murphy eye, we were apparently able to prevent retrograde migration of the EB in nine cases, including a difficult case with a presumed ectopic right upper lobe bronchus at the carina (Case 4, Fig. 2C and see Supplementary material online, Fig. 4).
An ETT of 4 mm ID was found (Case 1a) to accommodate a 4F Fogarty catheter and a 1.8 mm fibrescope simultaneously, but ventilation during bronchoscopy was difficult. Larger ETTs allowed more effective ventilation. Thus, clinicians should pre-test their EB and fibrescope to see if they can slide simultaneously within the ETT. For smaller ETT sizes, the EB stem needs to be outside the ETT (Cases 5 and 6). Advantages of this extra-luminal arrangement are that it does not affect flow through the ETT and does not need an Arndt multiport adapter. A swivel bronchoscope adapter with a Mini Step reducer9 would suffice. The pressure on the tracheal mucosa from the extra-luminal catheter is a concern, although anecdotal evidence would suggest that it may be well tolerated.10–12 The EB catheter reduces the calibre of the opening of the ETT tip. Thus, the ETT tip should be enlarged to reduce flow resistance (Fig. 1C and D, and see Supplementary material online, Fig. 3).
Theoretically, as the ETT tip is at the carina, inadvertent prolonged pressure on the carina may cause injury. However, we believe that ease of bilateral ventilation (before inflation of the EB) and of OLA (after inflation of the EB) are both incompatible with an ETT tip pressed tightly against the carina. In fact, by greatly reducing the risk of EB dislodgement and the need for multiple attempts at EB repositioning, our technique may actually reduce the risk of tracheobronchial injuries.
Our case series is small. We cannot claim that the technique would totally eliminate the problem of EB retrograde migration, especially if there is excessive manipulation and distortion of the lungs by the surgeon. Further studies are required.
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Supplementary material |
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Supplementary material is available at British Journal of Anaesthesia online.
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Funding |
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This work has been funded by departmental and institutional resources.
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Footnotes |
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This work is attributable entirely to the Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong SAR, People's Republic of China. 
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References |
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11 Filston HC, Chitwood WR Jr, Schkolne B, Blackmon LR. The Fogarty balloon catheter as an aid to management of the infant with esophageal atresia and tracheoesophageal fistula complicated by severe RDS or pneumonia. J Pediatr Surg (1982) 17:149–51.[CrossRef][Web of Science][Medline]
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