Is Muscle Relaxants Necessary during the Anesthesia for Cataract Surgery with LMA? / 대한마취과학회지

BACKGROUND: The recovery of spontaneous ventilation is delayed in elderly patients in whom muscle relaxants has been administered for general anesthesia. We evaluated the appropriateness of microscopic cataract surgery without using muscle relaxants in elderly patients. METHODS: Forty two ASA physical status I and II patients for cataract surgery were randomly assigned to two groups. Glycopyrrolate 0.2 mg, fentanyl 2 mcg/kg and propofol 2 mg/kg were administered intravenously followed by vecuronium 1 mg/kg iv in group I and 10% lidocaine 1.5 mg/kg spray into oropharynx in group II. Laryngeal mask (LMA) was inserted for airway management and anesthesia was maintained by only propofol infusion in both groups. Whether the patient moved during the surgery, whether ephedrine was administered and the propofol infusion rate were recorded. RESULTS: Six patients of group I and 1 patient of group II were moved during surgery. Only in group II, 7 patients received intravenously ephedrine administration. Mean infusion rate of propofol was 0.114 mg/kg/min in group I and 0.159 mg/kg/min in group II. CONCLUSION: In general anesthesia for microscopic cataract surgery, the combination of fentanyl 2 mcg/kg, propofol 2 mg/kg and infusion, 10% lidocaine spray and laryngeal mask without muscle relaxants is a good alternate method of keeping airway.

Is Muscle Relaxants Necessary during the Anesthesia for Cataract Surgery with LMA? / 대한마취과학회지

BACKGROUND: The recovery of spontaneous ventilation is delayed in elderly patients in whom muscle relaxants has been administered for general anesthesia. We evaluated the appropriateness of microscopic cataract surgery without using muscle relaxants in elderly patients. METHODS: Forty two ASA physical status I and II patients for cataract surgery were randomly assigned to two groups. Glycopyrrolate 0.2 mg, fentanyl 2 mcg/kg and propofol 2 mg/kg were administered intravenously followed by vecuronium 1 mg/kg iv in group I and 10% lidocaine 1.5 mg/kg spray into oropharynx in group II. Laryngeal mask (LMA) was inserted for airway management and anesthesia was maintained by only propofol infusion in both groups. Whether the patient moved during the surgery, whether ephedrine was administered and the propofol infusion rate were recorded. RESULTS: Six patients of group I and 1 patient of group II were moved during surgery. Only in group II, 7 patients received intravenously ephedrine administration. Mean infusion rate of propofol was 0.114 mg/kg/min in group I and 0.159 mg/kg/min in group II. CONCLUSION: In general anesthesia for microscopic cataract surgery, the combination of fentanyl 2 mcg/kg, propofol 2 mg/kg and infusion, 10% lidocaine spray and laryngeal mask without muscle relaxants is a good alternate method of keeping airway.

The Effect of Laryngeal Mask Airway on Postoperative Sore Throat in Prone Position / 대한마취과학회지

Background: Postoperative sore throat is a complaint after general anesthesia of multifactorial etiology. The laryngeal mask airway (LMA) reduces sore throat and discomfort during maintenance of the airway and make patients more comfortable. The purpose of this study was to compare effect of patient's position during operation on postoperative sore throat after the use of LMA. Methods: The fifty three patients were randomly divided into two groups. Group 1 (n=30) was underwent general anesthesia with supine position and group 2 (n=23) with prone position. After the LMA was positioned in the hypopharynx and the cuff inflated, fiberoptic laryngoscope was immediately passed down through the LMA. Number of attempts, degree of postoperative sore throat and other complications were also noted. Results: The incidence of postoperative sore throat after the use of LMA was 10% in supine position and 4% in prone position. But the difference between the groups was not statistically significant. All of the reported sore throats were rated as mild. Conclusions: Postoperative sore throat after the use of LMA is mild and the incidence is not affected by the prone position during the operation.

Endotracheal Intubation Using Laryngeal Mask Airway in a Patient with a Difficult Airway: A case report / 대한마취과학회지

Laryngeal mask airway (LMA) was designed as a new concept of airway management in anesthetic practice and has been successfully used in patients with difficult endotracheal intubation due to an abnormal upper airways. When It is in good position, one can cannulate the trachea either blindly or fiberoptic brochoscopically. In a patient with short neck and large breast, we were forced to use an emergency LMA because couldn't insert the laryngoscope. We decided to replace the LMA with an endotracheal tube to secure a definite airway. A fiberoptic bronchoscope was passed through both the endotracheal tube and the LMA to achieve endotracheal intubation. Then we attempted to remove the LMA for safe and smooth awakening. But the LMA coudln't be removed while keeping the LMA and the endotracheal tube in position. Therefore, surgery had to be proceeded with both the LMA and the endotracheal tube in place and all of which were removed after the surgical procedure. We conclude that the LMA is very useful as an aid of endotracheal intubation in patients with difficult airway.

Use of Direct Laryngoscope Improves a Hypopharyngeal Position of Laryngeal Mask Airway / 대한마취과학회지

BACKGROUND: Laryngeal mask airway (LMA) partly can be replaced for a role of endotracheal tube intraoperatively. Even with selecting one from various insertion techniques of LMA, one cannot achieve its perfect hypopharyngeal position. Furthermore, which is chosen by most anesthesiologists in this country, use of muscle relaxant for LMA insertion appears to have a harmful effect on its position. We tried to confirm whether we can improve the hypopharyngeal position of LMA with additional elevation of epiglottis using direct laryngoscope during LMA insertion. METHODS: Forty healthy patients scheduled for surgical procedure under general anesthesia were randomly divided to two groups; Laryngoscope group (n=20) and Jaw thrust group (n=20). No premedicant was administered. Anesthesia was induced with thiopental, vecuronium plus 2~3 vol% enflurane in oxygen. Full muscular relaxation was judged by no adductor response of thumb to train-of-four stimuation. In Jaw thrust group, using Brain's standard technique with additional jaw thrust, LMA was inserted, while in Laryngoscope group, LMA was introduced into oral cavity and advanced farther with additional elevation of epiglottis with direct laryngoscope. Bronchoscopic grading of hypopharyngeal position of LMA was performed. Blood pressure and heart rate were recorded at arrival (control), preintubation and until postintubation 5 minutes at 1 minute interval. Each measured values were compared between groups. RESULTS: Bronchoscopic grade of Laryngoscope group was significantly better than that of Jaw thrust group (p<0.001). Mean arterial pressure and heart rate changes were not different between groups. Conclusion: In the case of LMA insertion using muscle relaxant, we can markedly improve the hypopharyngeal placement of LMA with help of direct laryngoscope.

Comparative Effects of Laryngeal Mask Airway Insertion and Endotracheal Intubation on Intraocular Pressure during Induction with Propofol / 대한마취과학회지

BACKGROUND: It is important to control the intraocular pressure (IOP) during ophthalmic surgery. The precise control of IOP is an accepted advantage of general anesthesia. METHODS: The authors have compared IOP, blood pressure (BP) and heart rate (HR) with the insertion of laryngeal mask airway (LMA) or endotracheal tube (TI) during the induction of propofol. All data were recorded in the operating room upon arrival (Phase 1), just before the LMA or TI (Phase 2), immediately after (Phase 3), and 1 minute (Phase 4) and 3 minutes (Phase 5) after the LMA or TI. RESULTS: The IOP with the LMA was significantly lower at Phase 3 and Phase 4 than that with the TI. The changes of the IOP during Phases 2, 3, 4 and 5 was insignificant in LMA but significant in TI. The BP with LMA was significantly lower at Phases 3, 4 and 5 but the difference in HR was not significant between LMA and TI. CONCLUSION: The LMA offers advantages over TI for ophthalmic surgery in respect to the changes in IOP, BP and HR during the induction of propofol.

The Effect of Cuff Volume of Laryngeal Mask Airway on Cuff Pressure and Ventilation / 대한마취과학회지

BACKGROUND: The cuff inflation of laryngeal mask airway (LMA) with excessive volume of air may injure soft tissue and nerves around hypopharynx because of high cuff pressure. But it is not well known about adequate cuff volume of LMA. The cuff inflation of LMA in hypopharynx accomodate pharynx, so various injection volume may differ in sealing effect. This may influence ventilation. This study was proposed to investigate the effect of cuff volume on cuff pressure and ventilation when LMA inserted. METHODS: Fifteen male patients were inserted with #4 LMA, fifteen female patients were inserted #3 LMA. For male patients, 10, 20, 30 and 40 ml of air were injected into cuff of LMA and 10, 15, 20 and 25 ml for female patients. Cuff pressure, minute ventilation and airway pressure were randomly measured. RESULTS: Volume of injected into cuff and cuff pressure of LMA were closly related. But minute ventilation and airway pressure were not related with injected air volume of LMA. CONCLUSION: Excessive volume of air injected to LMA cuff was not beneficial to ventilation. So minimal sealing cuff volume under maximal recommended volume of LMA may reduce the incidence of complications associated with high cuff pressure.