LABORATORY ANIMALS The use of bougie-guided insertion of a laryngeal mask airway device in neonatal piglets after unexpected complications Ute Morath, 1 Hege Kippenes Skogmo, 2 Birgit Ranheim, 3 Olivier Louis Levionnois 1 1 Department of Veterinary Anaesthesiology and Pain Therapy, Vetsuisse Faculty, University of Bern, Laenggassstrasse 124, Bern 3012, Switzerland 2 Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway 3 Department of Food Safety & Infection Biology Section of Veterinary Pharmacology and Toxicology, Norwegian Veterinary School, PO Box 8146 Dep, Oslo 0033, Norway Correspondence to Dr Ute Morath, ute.morath@gmx.de Received 19 December 2013 Revised 5 February 2014 Accepted 24 February 2014 To cite: Morath U, Skogmo HK, Ranheim B, et al. Vet Rec Case Rep Published online: [ please include Day Month Year] doi:10.1136/vetreccr-2013- 000040 SUMMARY After marked airway obstruction with laryngeal mask (LM) placement in neonate piglets, anatomical observations in cadavers revealed a large epiglottis advancing markedly over the soft palate. CT imaging in vivo confirmed that the LM pushes the epiglottis caudally thereby obstructing the larynx. As a new approach, in 20 piglets a flexible PVC bougie placed under laryngoscopy was used to guide the LM to the correct position at the larynx. Placement of the bougie was easy and the LM was positioned successfully in all piglets at first attempt. In 14 piglets, the epiglottis was positioned dorsal to the soft palate before LM insertion and had to be pushed downwards to advance the bougie. In case of failure of LM placement with potential airway obstruction, the use of a bougie to guide the LM over the epiglottis was simple, rapid, and improved the success rate without complication. BACKGROUND Pigs are commonly used as experimental animals and some procedures require general anaesthesia. Inhalational agents are commonly used to maintain general anaesthesia when the duration is undefined and a rapid recovery is desired. Particularly in young piglets, induction of unconsciousness with an inha- lational agent delivered via face mask is effective and easily performed. However, prolonged main- tenance of inhalation anaesthesia via face mask com- pared with the use of an endotracheal tube may carry risks like unprotected airways, difficulties to adequately ventilate the patient, respiratory resist- ance as well as pollution of the environment and exposure of the operators to anaesthetic gases (Bateman and others 2005). On the other side, endotracheal intubation can be challenging, particu- larly in small individuals, and requires experience and training. The use of a laryngeal mask (LM) is an appropriate alternative to endotracheal intubation, providing an airtight seal around the laryngeal inlet with the option to ventilate the animal if necessary (Wemyss-Holden and others 1999, Fulkerson and Gustafson 2007). Its use in neonate swine has been described once by Roberts and others (2010) as safe, uncomplicated and rapid. Moreover, the LM has been used to achieve ventilation in human patients in whom tracheal intubation or ventilation through facemask has failed (Asai 1996); it thus has a poten- tial role in patients with difficult airways. In a series of neonate piglets the LM was chosen to deliver inhalation anaesthesia. During placement of the supraglottic airway device, complications occurred in a majority of animals. Further investiga- tions and development of a modified insertion tech- nique to improve the success rate were completed. CASE PRESENTATION During an experimental study in 16 neonate piglets (one to two weeks old) for central venous catheter placement, general anaesthesia was induced by administration of isoflurane in 100 per cent oxygen via face mask. To maintain inhalational anaesthesia throughout the procedure, the placement of a LM (Laryngeal Airway, Standard Reusable Silicone, size 1, Pro-Breathe range, Proact Medical Ltd, UK) was attempted. The animals were placed in lateral recumbency with the neck in a natural non- extended position. The cuff of the LM was not fully deflated so the leading edge was smooth and firm. Before insertion of the LM a very thin layer of sterile lubricating gel was applied. After removal of the facemask, the cuff was placed in the mouth cavity with 90° rotation to the tongue. The LM was then rotated in its functional position, and advanced pressed against the palate while the tongue was immobilised until a definite point of resistance was met and the whole tube was inserted. Absence of rotation of the LM tube was verified and the cuff inflated with 3–4 ml of air. During inflation, place- ment in the larynx was confirmed by a slight outward movement of the tube (less than 1 cm) and resistance while pulling it softly. The airway device was immediately connected to a Bain breathing system. Airway patency was verified by capnography and observation of thorax excursion and movements of the reservoir bag. Unfortunately, 11 out of 16 individuals (62.5 per cent) immediately showed signs of marked respiratory obstruction with a lack of a normal shaped capnogram and therefore several replacements of the airway device were necessary. In seven piglets, facemask was applied after the third attempt. In the last piglets, standard direct laryngoscopy revealed that the rostral portion of the epiglottis was advanced in a dorsal direction over the soft palate. Neither extension or bending of the neck, nor pulling of the tongue brought any improvement to free and visualise the tracheal inlet without direct manipulation of the epiglottis. INVESTIGATIONS Observations from the placement of LM in cada- vers of three other piglets at the age of two weeks (same breed, different litter) and anatomical Morath U, et al. Vet Rec Case Rep 2014;2:e000040. doi:10.1136/vetreccr-2013-000040 1 Veterinary Record Case Reports group.bmj.com on June 19, 2014 - Published by vetrecordcasereports.bmj.com Downloaded from