To compare the advantage and disadvantage of isobaric and hyperbaric tetracaine spinal anesthesia, ninety, either sex, adult patients scheduled for knee arthroscopy were assigned randomly into two groups; one with the isobaric (n=70), and the
other
with
the hyperbaric (n=20) tetracaine spinal anesthesia. The isobaric solution was prepared to 0.5% tetracaine in 50% cerebrospinal fluid of the patient's own and the hyperbaric solution to 0.5% tetracaine in 5% dext5rose in water.
Epinephrine was mixed to either solution in the ratio of 1 : 200,000. The dosage of tetracaine was determined by the patient's height; 0.1 mg/cm height-difference, added or reduced to the reference dose of 12 mg/160cm.
The site of lumbar puncture was L2-3 intervertebral space and 22 G Quincke spinal needle used. The speed of injection was fixed to the rate of 1 ml/10 sec.
The onset, duration and maximal anesthetic level (MAL) in both groups were not significantly different and blood pressure and heart rtte decreased with the elapsed time during anesthesia in similar pattern in both groups. And also, there was no
significant difference in postspinal anesthetic complications such as headache, hypotension, etc.
In conclusion, there was no significant difference in clinical aspects between hyperbaric and isobaric tetracaine spinal anesthesia for knee arthroscopy, with corresponding doses and strength of tetracaine, technics in room temperature.
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