Children need to be sedated safely to stop them moving and ensure homeostasis of vital functions during magnetic resonance imaging. In the search for a minimally invasive method with little environmental pollution to allow accurate constant monitoring of the level of anaesthesia and upper airway patency, we used the laryngeal mask combined with general inhalational anaesthesia in spontaneous breathing. Over a period of 18 months, 482 children without premedication in class ASA 1-III (aged 5.5 + 4.3 years; range 1 day - 18 years) with CNS disease were consecutively given anaesthesia by laryngeal mask to undergo MR brain scan. Using an 'F' Mapleson circuit modified by elongating the inspiratory and expiratory branches and connecting the latter with a 'Venturi' aspiration system, anaesthesia was induced by making the child, accompanied by a parent, breathe in rapidly increasing concentrations of halothane in a 50% oxygen and nitrous oxide gas mixture. On disappearance of the ciliary reflex, the parent left the child and cannulation was performed through a peripheral vein and a laryngeal mask of an appropriate size was inserted. Using an a-magnetic monitor compatible with the high magnetic fields present, trans-cutaneous oxygen saturation and ECG were monitored together with non-invasive measurement of arterial pressure, partial CO2 pressure at the end of expiration and the concentration of halogenate and the gas mixture. The child was then placed inside the magnet continuing the anaesthesia in spontaneous breathing with halothane at 1.5 of the minimum inhibitory alveolar concentration (MAC) in a gas mixture of oxygen and air with a minimum respiratory flow of 300 ml/kg/min. Roughly halfway through the examination the concentration of halothane was reduce to around 1.0 MAC. At the end of the MR examination the halogenated anaesthetic was suspended removing the laryngeal mask on the appearance of the first upper airway reflexes. The child was then put to bed in another room where s/he could wake next to the parent who had accompanied the child earlier. There were no cases of significant desaturation, hypotension, bradycardia, arrhythmias, convulsions or other clinically significant incidents either on anaesthesia induction, during the MR scan or on awakening. No gastrointestinal reflux occurred. This two-year study demonstrates that inhalational anaesthesia during spontaneous breathing through a laryngeal mask for magnetic resonance imaging in children is safe and effective.
|Number of pages||6|
|Journal||Rivista di Neuroradiologia|
|Publication status||Published - 2000|
ASJC Scopus subject areas
- Clinical Neurology
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology