Three diagnostic conundrums solved using the laryngeal mask airway

Comparative evaluation of TIVA with propofol-fentanyl and thiopental-sevoflurane anesthesia using laryngeal mask airway for diagnostic bronchoscopy

PURPOSE

Diagnostic bronchoscopy is performed under general anesthesia in our hospital. This study was designed to determine whether total intravenous anesthesia (TIVA) with propofol-fentanyl provides more stable hemodynamics using a laryngeal mask airway (LMA) for diagnostic bronchoscopy than thiopental-sevoflurane anesthesia.

METHODS

Sixty patients scheduled for diagnostic bronchoscopy were randomly assigned to two groups. TIVA with propofol-fentanyl was induced with intravenous fentanyl 2 μg·kg^-1 and propofol 2 mg·kg^-1 and maintained with continuous infusion of propofol with fentanyl. Thiopental-sevoflurane anesthesia was induced with thiopental 5 mg·kg^-1 and maintained with N₂O/O₂/sevoflurane. Insertion of the LMA was facilitated with vecuronium 0.1 mg·kg^-1 i.v. in both groups. Ventilation was controlled, and administration of propofol and sevoflurane was continued until the end of the procedure. The LMA was removed when the patient was able to open his or her mouth.

RESULTS

During TIVA, the mean arterial pressure and rate pressure product decreased significantly from induction until 20 min after the start of the procedure, and they were maintained at around 70 mmHg and 7000, respectively, during the procedure. There were no significant differences in heart rate,[Formula: see text] and[Formula: see text]. In thiopental-sevoflurane anesthesia, the mean arterial pressure and rate pressure product decreased significantly after induction and increased significantly from insertion of the LMA until removal of the LMA. Heart rate increased significantly after insertion of the LMA, insertion of the bronchoscope, and removal of the LMA. There were no significant differences in[Formula: see text] and[Formula: see text].

CONCLUSION

TIVA with propofol-fentanyl in conjunction with an LMA performs better than thiopental-sevoflurane anesthesia for diagnostic bronchoscopy because of its superior maintenance of cardiovascular stability.

The laryngeal mask airway: potential applications in neonatal health care

The laryngeal mask airway is a completely new concept in airway management and has the potential to provide a third airway option for the neonate. The device sits in the hypopharynx at the interface between the gastrointestinal and respiratory tracts, where it forms a circumferential low-pressure seal around the glottis. This article provides an overview of the laryngeal mask airway and focuses on its potential as a neonatal airway outside the operating room.

The laryngeal mask airway: a new technique for fiberoptic guided vocal cord biopsy

STUDY OBJECTIVE

To describe a new technique for vocal cord biopsy involving placement of a laryngeal mask airway (LMA) during general anesthesia and fiberoptic guided biopsy. To report our early experience with this technique.

DESIGN

Descriptive study.

SETTING

Teaching hospital.

PATIENTS

10 patients undergoing vocal cord biopsy for minor laryngeal pathology and with no evidence of infraglottic airway obstruction.

INTERVENTIONS

Patients were premedicated 1 hour preoperatively with pethidine 1 mg/kg and atropine 0.01 mg/kg. Following preoxygenation, anesthesia was induced with propofol 2.5 mg/kg and fentanyl 1 mg/kg. Once airway control was established with a facemask, vecuronium 0.1 mg was given and anesthesia established with oxygen (O2) and nitrous oxide mixture and isoflurane 1% to 2%. Gentle direct laryngoscopy was then performed to inspect the pharyngeal structures and the LMA was then inserted in the standard manner by highly experienced LMA users. A fiberoptic scope was passed via a self-sealing mount down the shaft of the LMA to the level of the vocal cords. The vocal cords were then sprayed with local anesthetic and the biopsy taken.

MEASUREMENTS AND MAIN RESULTS

The age and weight range were 29 to 57 years and 65 to 85 kg, respectively. All patients were smokers or recent ex-smokers. LMA insertion was readily achieved in all patients, and an excellent view of the vocal cords was obtained. There were no problems with ventilation or obtaining tissue samples, and O2 saturation remained greater than 95% throughout the perioperative period. Tissue samples were adequate in all patients. Hypertension and other adverse cardiac events did not occur during the procedure, which lasted 10 to 20 minutes. There were no problems during emergence from anesthesia, and all patients were discharged home on the same day.

CONCLUSIONS

The technique has potential advantages over suspension microlaryngoscopy in that it is relatively noninvasive, it allows good airway control with adequate views of the vocal cords, and it facilitates a smooth recovery.

A new diagnostic approach to congenital stridor using a laryngeal mask airway and rigid endoscope

Neonates with symptoms of stridor from birth, present a difficult diagnostic problem. We have demonstrated that by the use of a laryngeal mask airway in an anaesthetized baby breathing spontaneously, we are able to reach a diagnosis. This is accomplished by the introduction of a rigid fibre-optic endoscope through a Portex swivel connector and visualizing the glottis and larynx.

The laryngeal mask airway: its features, effects and role

The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anaesthetic practice. Numerous articles and letters about the device have been published in the last decade, but few large controlled trials have been performed. Despite widespread use, the definitive role of the laryngeal mask has yet to be established. In some situations, such as after failed tracheal intubation or in anaesthesia for patients undergoing laparoscopic or oral surgery, its use is controversial. There are a number of unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoid pressure prevents placement of the mask. We review the techniques of insertion, details of misplacement, and complications associated with the use of the laryngeal mask. We discuss the features and physiological effects of the device, including the changes in intra-cuff pressure during anaesthesia and effects on blood pressure, heart rate and intra-ocular pressure. We then attempt to clarify the role of the laryngeal mask in airway management during anaesthesia, based on the current knowledge, by discussing the advantages and disadvantages as well as the indications and contraindications of its use. Lastly we describe the use of the laryngeal mask in circumstances other than airway maintenance during anaesthesia: fibreoptic bronchoscopy, tracheal intubation through the mask and its use in cardiopulmonary resuscitation.