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Fiberoptic-Guided Endotracheal Intubation via the Laryngeal Mask Airway in Pediatric Patients

1996; Lippincott Williams & Wilkins; Volume: 82; Issue: 6 Linguagem: Inglês

10.1097/00000539-199606000-00032

1526-7598

Christopher M.B. Heard, L. D. Caldicott, James E. Fletcher, Daniel S. Selsby,

Anesthesia and Sedative Agents

The laryngeal mask airway is increasingly being used in pediatric anesthesia [1-3]. The placement of the laryngeal mask airway in children results in an acceptable airway in more than 90% of patients [1] on the first attempt and in almost 100% on subsequent attempts. Experience in its use has increased to a degree where it is now being used for patients in whom airway management is difficult, with no untoward effects reported in previously published case reports [4-10]. In some of these cases, the laryngeal mask airway has been used instead of endotracheal intubation [5,10], but this may not always be possible and an endotracheal tube may be required. There have been case reports of the laryngeal mask airway being used to facilitate endotracheal tube placement using guides such as catheters [4] or light stylets [6]. These were placed blindly and hence had a risk of not being correctly positioned. The problem-free use of a fiberoptic bronchoscope through a laryngeal mask has been described for diagnostic bronchoscopy in children [7]; it has also been used with a guide wire to assist endotracheal intubation [8]. In our cases, we assessed a technique using a laryngeal mask airway to facilitate the use of a fiberoptic bronchoscope to position a guide wire under direct visualization for directing the placement of an endotracheal tube Figure 1. This technique allows for the maintenance of both oxygenation and inhalational anesthesia during the positioning of the bronchoscope via the laryngeal mask airway, up to the moment of passing the endotracheal tube over the guide wire.Figure 1: After the fiberoptic bronchoscope is placed through the size 2 laryngeal mask airway, the guidewire is then passed through the suction port of the bronchoscope.Case Reports The use of this technique was approved by the hospital ethics committee. Informed, written consent was obtained from all parents. Fifteen ASA grade I or II children undergoing elective dental procedures requiring oral endotracheal intubation underwent intubation with this technique. Patients were excluded if they had gastrointestinal disease, were not appropriately fasted, or were known to be difficult to intubate. They also had to be suitable for the placement of a size 2 laryngeal mask (patient weight approximately 6-25 kg). Anesthesia was induced with intravenous sodium thiopental 5 mg/kg and maintained with oxygen, nitrous oxide, and halothane using a face mask and T-piece circuit. Monitoring included electrocardiograph, pulse oximetry, and noninvasive blood pressure measurements recorded at 1-min intervals. The endotracheal tube diameter size was chosen according to the following formula: age/4 + 4.5 mm. After 3 min of spontaneous ventilation, a laryngeal mask was placed and then the fiberoptic bronchoscope (Olympus LF-1, outer diameter 3.5 mm; Olympus, Melville, NY) was passed via a sealed port in the angle piece until the vocal cords were clearly seen. The patients were then given atracurium 0.5 mg/kg and their lungs gently hand ventilated via the laryngeal mask airway while a guide wire (0.0035-in., Teflon-coated, "floppy end" straight cardiac catheter wire, 150 cm; Mallinckrodt, St. Louis, MO) was passed down the suction port of the bronchoscope. After 150 s of hand-assisted ventilation, the guide wire was passed through the vocal cords (approximately 3-5 cm). The laryngeal mask airway and bronchoscope were then carefully withdrawn. The endotracheal tube was then passed over the guide wire into the trachea. The guide wire was then withdrawn, and endotracheal tube placement was confirmed by capnography and auscultation of the chest. The time required, success rate, and any complications that occurred during the procedure were documented. The mean time taken to perform intubation was 427 s from induction of anesthesia Table 1. There were no changes in heart rate and blood pressure that we felt were of clinical significance Table 2. There was a minimal decrease from baseline in the oxygen saturation. One patient developed stridor, but this did not require any specific treatment and there was no decrease in oxygen saturation.Table 1: Patient Data, Time to Successful Intubation, and ComplicationsTable 2: Systolic Blood Pressure, Heart Rate, and Change in Oxygen Saturation (SpO (2))Discussion Our series of case reports has demonstrated that the fiberoptic technique can be used safely and without undesirable cardiovascular or respiratory side effects in healthy children. Although it took longer to perform than direct laryngoscopy, the airway was easily maintained by the laryngeal mask, and only one patient's saturation decreased to 92% during the technique. In another case, there was some stridor on placing the guide wire through the vocal cords, but this settled spontaneously by the time the endotracheal tube was positioned and there was no decrease in oxygen saturation. The Teflon-coated cardiac catheter wire was selected to allow easy passage of the endotracheal tube over it. However, we found that rotation of the endotracheal tube was sometimes necessary in order to bring the tip anterior to the arytenoid cartilages [11]. When using this technique for an anticipated or known difficult intubation, the anesthesiologist may elect to induce anesthesia by inhalation of halothane in oxygen. Use of a laryngeal mask airway may then allow control of the airway before and during the placement and manipulation of the bronchoscope. If it is not possible to place the laryngeal mask, then other methods for intubating the child's trachea will have to be chosen. In such cases, the airway will not have been compromised by our technique. The correct position of the laryngeal mask airway may first be confirmed by the fiberoptic bronchoscope and any necessary adjustments in position made. Once the cords have been correctly identified, intubation can be facilitated either by deepening the plane of anesthesia or by using a neuromuscular blocking drug after ensuring that the patients' lungs can be ventilated via the laryngeal mask airway. In conclusion, we have described a safe and successful method for endotracheal intubation of the pediatric patient that can be easily learned. Experience in our technique may prove invaluable for treating patients in whom endotracheal intubation is difficult using direct laryngoscopy.