Paediatric Anaesthesia 1995 5: 197-198

Case report T h e laryngeal mask airway forfibreoptic bronchoscopy in children

ANIS BARAKA FRCA (Hon), PATRICK CHOUEIRY ID AND ANTOINE MEDAWWAR MD

Departineiif of Anesthesiology, American University of Beirut, Beirut-Lebanon

Summary A size 2 laryngeal mask airway (ID 7 mm) was used for general anaesthesia during fibreoptic bronchoscopy in a six-year-old child. The mask permitted the use of an adult bronchoscope with an external diameter of 5 mm. Throughout bronchoscopy, adequate controlled ventilation could be achieved easily without excessive air leak or airway resistance; the Spo, was always >97%, and the end- tidal Pco, ranged between 3.94.5 kPa (30-35 mmHg).

Keywords: bronchoscopy; fibreoptic; airway; laryngeal mask

Introduction Flexible fibreoptic bronchoscopy in children is usually performed under general anaesthesia and tracheal intubation. The major limitation of this technique is the inability of a large adult fibreoptic bronchoscope (FOB) to pass through small paediatric tracheal tubes. This problem is partially alleviated by the new smaller paediatric FOB. However, the paediatric FOB are not available in many centres, and if available, they may not pro- vide the best view of the lower airways.

The laryngeal mask airway (LMA) has been pre- viously suggested as a useful device for fibreoptic bronchoscopy in infants (Maekawa et al. 1991), as well as in the adult patients (McNamec, Meyns & Pagliero 1991; Nagel & Dich-Nielsen 1993). The pre- sent report shows that the LMA may also be useful for fibreoptic bronchoscopy in children since it per- mits the use of a large or even an adult FOB.

Correspoiideiice to: Anis Baraka MD, FRCA, Professor & Chair- man, Department of Anesthesiology, American University of Beirut, Beirut-Lebanon.

Case history A six-year-old, 25 kg boy was scheduled for flexible fibreoptic bronchoscopy under general anaesthesia. Chest x-ray showed opacity of the left lower lobe of lung (Figure 1).

The child was premedicated with intramuscular atropine 0.4 mg. Following preoxygenation, anaesthesia was induced with propofol 2 mgkg-’ and suxamethonium 2 mgkg-’. A size 2 LMA (ID 7 mm) was easily inserted and its rim was inflated with 10 ml of air. A swivel connector with a self- sealing rubber diaphragm was attached to the shaft of the mask. Manual controlled ventilation using the T-piece circuit was easy without evidence of resistance or excessive air leak. Anaesthesia was maintained with 50% nitrous oxide in oxygen, supplemented by suxamethonium drip and inter- mittent doses of propofol. The child was continu- ously monitored by ECG, pulse oximetry and end-tidal capnograph. The end-tidal Pco, was monitored by Ohmeda 5200 CO, monitor, with the aspiration tube located between the laryngeal mask adaptor and the T-piece circuit.

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198 A. BARAKA, P. CHOUEIRY & A. MEDAWWAR

Figure 1 Chest x-ray showing opacity of the left lower lobe of lung.

The flexible FOB (Olympus P 20 D) with an exter- nal diameter of 5 mm was inserted through the PVC cap of the swivel connector which formed an air- tight seal around the bronchoscope. Automatic jet ventilation (Baraka et al. 1994) was maintained using a low inspiratory to expiratory time ratio of 1:3 to facilitate passive exhalation around the broncho- scope and to minimize the potential hazard of inad- vertent pneumothorax. The relatively good seal of LMA around the laryngeal aditus, together with the good fitting of the rubber diaphragm of the swivel connector around the FOB allowed adequate con- trolled ventilation with minimal air leak. Through- out bronchoscopy, the oxygen saturation (SpoJ was always above 97%' and the end-tidal Pco, ranged between 3.9-4.5 kPa (30-35 mmHg).

Fibreoptic bronchoscopy showed a whitish glistening membrane obstructing the left lower lobe bronchus, suggestive of ruptured hydatid cyst. The membrane was suctioned and taken for biopsy. At the end of the procedure, suxamethonium drip was discontinued and the child was ventilated with 100% oxygen until complete recovery was observed.

Discussion Flexible fibreoptic bronchoscopy during general anaesthesia involves the introduction of the FOB through a tracheal tube or LMA, and hence the relationship of their internal diameter to the external diameter of the bronchoscope is critical.

The paediatric LMA will have a larger ID than the equivalent tracheal tube that would have to be used

Table 1 The internal diameter (ID) of the shaft of LMA, as compared to the ID of the tracheal tubes that have to be used in the same child

Laryngeal mask airway Body weight Tracheal tube

ID (mm) (kg) Size ID (mm)

<6.5 1 5.25 3.5 6.5-20 2 7.0 4.5

20-30 2.5 8.4 5.0 >30 3 10.0 6.0

in the same age group (Table l), and hence it can accommodate the FOB without a significant decrease of the airway around the bronchoscope (Pennant & White 1993). This will provide adequate controlled ventilation, facilitate passive exhalation and minimize air trapping. Also, the LMA allows the use of a larger FOB which provides a better view of the lower airways. Smaller FOBS are necessary whenever we need to visualize air- ways smaller than the entrance to lobar bronchi. In addition, the LMA can allow an unimpaired dynamic view of the vocal cords during lightening of anaesthesia.

Conclusion The present report shows that the LMA is a useful device in children undergoing fibreoptic bron- choscopy under general anaesthesia. The internal diameter of the shaft of the mask permits the use of a relatively large FOB, without a significant increase of airway resistance. Thus, adequate oxygenation and carbon dioxide elimination can be maintained throughout bronchoscopy.

References Baraka A., Muallem M., Chidiac G. & Ayyoub C. (1994) Auto-

matic jet ventilation in children anaesthetized by the T-piece circuit. Paediafric Anaesthesia 4, 169-172.

McNamec C.J., Meyns B. & Pagliero K.M. (1991) Flexible bron- choscopy via the laryngeal mask a new technique. Thorax 46,

Maekawa N., Mikawa K., Tanaka O., Coto R. & Obara H. (1991) The laryngeal mask may be a useful device for fibreoptic air- way endoscopy in paediatric anaesthesia. Anaesthesioiogy 75,

Nagel P. & Dich-Nielsen J.G. (1993) Flexible fiberoptic bron- choscopy via the laryngeal mask. Acta Anaesthesiologica Scandi- nauica 37, 17-19.

Pennant J.H. & White P.F. (1993) The laryngeal mask airway. Its uses in anesthesiology. Anesthesiology 79, 144-163.

141-142.

169-170.

Accepted 28 October 1994

0 1995 Arnette Blackwell Ltd, Paediatric Anaesthesia, 5,197-198