TITLE: MODIFIED SIMPLE TECHNIQUE OF ANESTHETIC INDUCTION IN ADULTS BY ADMINISTERING SEVOFLURANE VIA THE FACE MASK

AUTHORS: Michiaki Yamakage, MD, PhD, Jun-ichi Hattori, MD, Yasuhiro Kamada, MD, Naoki Tsujiguchi, MD, Akiyoshi Namiki, MD PhD
AFFILIATION: Sapporo Medical Univerisity, Sapporo, Japan.

INTRODUCTION: Anesthetic induction can be achieved rapidly using the vital capacity ("single breath") technique (8% sevoflurane), which typically produces loss of consciousness in 50-55 s and is associated with minimal complications.^1,2 The disadvantages of this technique are that it requires a breathing circuit with a large reservoir (priming with 8% sevoflurane), more cooperation is required from the patient, and preoxygenation is only possible if a separate breathing circuit is available. We reported modified simple technique of anesthetic induction in adults by administrating sevoflurane via the face mask.
PATIENTS AND METHODS: One hundred ASA physical status I or II adult patients who required general anesthesia for minor surgery were enrolled in this study. The patients were randomly divided into two groups: control (n=50) and midazolam (n=50) groups. The midazolam group received intramuscular premedication of 0.05mg/kg midazolam 45 min prior to the anesthetic induction. The patients were breathing room air before anesthetic induction. They were instructed to breathe out to residual volume and then the anesthetic mask was fitted tightly. They were then told to take repeated vital capacity breaths as deep as possible and anesthesia was induced by 5% sevoflurane in oxygen (10 l/min) via the mask. After the end of 3- times of vital capacity breaths, fresh gas was changed to 3 l/min oxygen and 6 l/min nitrous oxide. Loss of consciousness was defined as loss of eyelash reflex. Induction time, the excitatory complications (ex. cough, laryngospasm, movement of a limb, etc.), and acceptability (smell) were recorded by an independent observer.
RESULTS: Induction time of the midazolam group (58 +/- 5 s) was significantly shorter than that of the control group (66 +/- 6 s). All excitatory complications (4 cases, 8%) were observed in the control group. Acceptability was significantly higher in the midazolam group (96%, pleasant or no comment) than in the control group (68%).
CONCLUSION: Modified simple technique of volatile induc- tion with sevoflurane up to 5%, which does not need special circuit, was very smooth and safe compared to capacity breathing technique1,2. Hypnotic premedication such as midazolam is recommended to use for more smooth induction and the patient's comfort.
REFERENCES:

1. Anaesthesia 1997;52:410,

2. Anesth Analg 1993;76:598.