Sir,The number of diagnostic and therapeutic procedures performed outside the operation theatre has increased over the last decade and providing anaesthesia and sedation will be a real challenge to the anaesthetisiologists. Sedation for magnetic resonance imaging (MRI) procedures in children adds a substantial risk in younger children. This is more so in paediatric patients with difficult airway.[1]A 4 years male child weighing 16 kg presented to paediatric department with a huge swelling of tongue since birth. He had undergone resection of the same at 6 months of age which had recurred (size approximately around 6 cm × 4 cm). He had difficulty in speech and feeding, and, of course, cosmetic issue to his family and society. Paediatricians suspected venolymphatic malformation and to confirm the diagnosis child was advised MRI neck. During preanaesthetic evaluation, we noted the profusely enlarged tongue which was protruding out of oral cavity [Figure 1]. The child was unable to protrude his tongue as it was covering the entire oral cavity. Availability of all emergency drugs and difficult airway cart including fibreoptic bronchoscope were confirmed in the MRI suite.
Figure 1
(a and b) Profusely enlarged and protruding tongue
(a and b) Profusely enlarged and protruding tongueParental consent was obtained, and the child was fasted for 6 h for solids and 2 h for clear liquids. Monitoring with pulseoximeter and electrocardiogram (ECG) were initiated, and baseline heart rate (HR), and blood pressure were recorded. Intranasal dexmedetomidine 1 μg/kg and eutectic mixture of lignocaine and prilocaine cream was applied 30 min before securing a 22 gauge intravenous cannula over dorsum of the left hand. Injection glycopyrrolate 10 μg/kg was administered. Oxygen through nasal prongs was delivered at 2 L/min. Injection dexmedetomidine 0.5 ΅g/kg (IV)was administered over 10 min. The sedated child was taken to MRI console (Ramsay sedation score of 5).[2] An MRI compatible monitor was used to monitor HR, ECG and oxygen saturation and respiration through a sidestream capnography continuously and patient remained stable throughout the procedure lasting for 20 min. In the recovery room, the child was made to lie in the left lateral position. Monitoring and oxygen supplementation were continued. The child made an uneventful recovery from sedation.Venolymphatic malformations are slow-flow lesions that are a combination of dilated lymphatic channels filled with proteinaceous fluid and large veins. These can be difficult to separate from other low flow lesions such as lymphatic malformations and haemangiomas on certain imaging, especially ultrasound. The presence at birth favours venolymphatic malformation, although the other two do occur at birth.[3] Computed tomography and MRI are used for volumetric analysis of haemangiomas and vascular malformations. Imaging resources are useful in both diagnostic differentiation and analysis of lesion features with regard to its size, extension and location, as well as for follow-up of lesions treated under a systemic therapy.[4]MRI suite is unlikely to be a favourable place to give sedation or anaesthesia for many reasons. Patient's distance from anaesthesiologist creates problems such as airway management, intravenous access, patient visualisation and monitor attachment.[5] MRI compatible machines and airway instruments are required and patients may suffer due to claustrophobia, noisy unfamiliar environment, hypothermia, and strong magnetic field.Children require moderate to deep sedation during MRI procedures to avoid movement and image distortion. The potential complications of deep sedation include hypoventilation, apnoea, airway obstruction, bradycardia and hypotension. An appropriate drug which causes minimal cardiorespiratory depression has to be used. Dexmedetomidine (a highly selective α2 -adrenoreceptor agonist) as a sedative agent will provide a controllable sedation and analgesia without cardiorespiratory depression.[6] An interesting feature regarding oral use of dexmedetomidine is that after oral administration for paediatric sedation, the absorption is to the extent of 82%.[7] Although dexmedetomidine and propofol provide adequate sedation in children, propofol provides more rapid rates of anaesthetic induction and recovery but dexmedetomidine better preserves mean arterial pressure and respiratory rate.[8]Thus, we conclude that drugs which provide a controlled sedation without cardiorespiratory depression like dexmedetomidine can be very useful for sedation in paediatric patients with difficult airway outside operation theatre.
Figure 1