Comparison of auditory evoked potential index and clinical signs as indicator for laryngeal mask airway insertion.

OBJECTIVE: Auditory evoked potential (AEP) index is one of the several physiological parameters for assessing the depth of anesthesia. The purpose of this study was to investigate whether the AEP monitoring could provide a better information for assessment of anesthesia level in classic laryngeal mask airway (C-LMA) insertion than the use of clinical signs in general anesthesia with single standard dose of intravenous propofol and fentanyl. METHODS: One hundred and seventy adult patients requiring general anesthesia for minor surgery were recruited and randomized to receive AEP monitoring (group A) or judgment of clinical signs (group B) for assessment of anesthesia depth and optimal condition to insert the C-LMA. The insertion conditions, including jaw relaxation, movements, presence of airway trauma and airway reflex, successful insertion rate and induction time were recorded and compared. RESULTS: The two groups were demographically similar. In group A, baseline heart rate was slower than group B (74 ± 14 vs. 78 ± 14 beats/min, p = 0.0267) and persisted throughout the whole study period. There was no significant difference in the change of heart rate during induction of general anesthesia between both groups. The incidence of movement was reduced in group A patients with AEP monitoring in comparison with group B patients (2.4% vs. 28.2%, p < 0.0001); of the unwanted events, swallowing was 0% versus 7.1%, p = 0.0126; laryngospasm was 0% versus 4.7%, p  = 0.0430 and emergence of airway reflex was 1.2% versus 11.8%, p = 0.0050; the successful insertion rate was 100% versus 94.1%, p = 0.0232; and jaw relaxation was 83.5% versus 70.6%, p = 0.0448. There were no differences between both groups in trauma and induction time. CONCLUSION: This study demonstrated that AEP index provided better information for C-LMA insertion with higher successful rate, less emergence of airway reflex and lower incidence of movement during induction of general anesthesia with single dose of intravenous propofol and fentanyl.

A survey for prevention and treatment of malignant hyperthermia in Taiwan.

BACKGROUND: Malignant hyperthermia (MH) is a hypermetabolic disorder with high mortality. Intravenous administration of dantrolene is the specific treatment. However, the only means to lower mortality rate are early detection and suitable treatment. Therefore, properly monitoring and handy availability of dantrolene are essential to lower the mortality of MH. This study was designed to evaluate the capabilities in prevention and treatment of MH of the hospitals in Taiwan. METHODS: There were 102 certified training hospitals (including medical centers and regional hospitals) in Taiwan selected for this study. A questionnaire was designed to evaluate the capabilities of these hospitals in dealing with prevention and treatment of MH. RESULTS: A total of 66 copies of the questionnaire were returned, which gave a response rate of 64.7%. The results of the survey are as follows: Succinylcholine was frequently used for induction in 92% of the hospitals investigated. For monitoring during general anesthesia, pulse oximeter was routinely used in 66(100%) hospitals, and ETCO2 monitor in 51 (77.3%) hospitals but continuous body temperature was routinely monitored only in 13 (19.7%) hospitals. Six or more vials of dantrolene were stored and available for immediate use in 23 (34.9%) hospitals and the rest of 43 (65.1%) hospitals did not have any stock of dantrolene at all. Of these 43 hospitals, 25 (58.1%) relied on other hospitals to supply dantrolene and the time required to obtain dantrolene from other hospitals was 70.7 +/- 34.7 min. There were 21 cases who sustained MH in 17 (25.8%) hospitals in the past ten years, of whom 15 were resuscitated successfully and 6 died, thus giving a mortality rate of 28.6%. CONCLUSIONS: This study has revealed that in some hospitals in Taiwan intraoperatively (anesthetic) monitoring is inadequate and there is no stockpile of dantrolene for immediate treatment of MH. We recommend that appropriate anesthetic monitoring equipment should be strictly applied and a stock of initial dose of dantrolene (6 vials) should be kept, which are necessary for early diagnosis and treatment of MH.