The Monitoring of PETCO2 via Nasal Cannula in Spontaneously Breathing Patients during Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Monitoring of PETCO2 in the patients during regional anesthesia may be no less important than under general anesthesia, but will aid in early detection of potentially catastrophic events. However, the utility and accuracy of capnography in non-intubated patients has received little attention. We examined correlation between PETCO2 measured via nasal cannula and PaCO2 values in the sedated spontaneously breathing patients during spinal anesthesia. METHODS: Thirty adult patients who underwent elective surgery were administered optimal doses of tetracaine and epinephrine mixture in their site of operation, length, weight and age. Thereafter, we sampled expired gas by 175ml/min and administered oxygen by 3L/min using oxygen delivery CO2 sampling nasal cannula. End tidal carbon dioxide tension, heart rate, blood pressure and respiratory rate were measured before and 20 min after 0.02 mg/kg midazolam i.v.. And arterial blood gases were once measured 20 min after 0.02 mg/kg midazolam i.v.. RESULTS: The patients, sedation state was asleep or calm in awake. End tidal carbon dioxide tension was significantly increased after midazolam injection (p<0.01), but another values were not different after midazolam injection. Linear regression analysis of arterial carbon dioxide tension and end tidal carbon dioxide tension after midazolam injection yielded y = 0.77x + 4.82 and r2 = 0.76 (p<0.01). CONCLUSIONS: End tidal carbon dioxide tension using oxygen delivery CO2 sampling nasal cannula in the sedated spontaneously breathing patients with midazolam during spinal anesthesia were significantly related with arterial carbon dioxide tension. Therefore, we conclude that monitoring of PETCO2 via nasal cannula is a reliable means during spinal anesthesia.

The Change in P300 Component of the Long Latency Auditory Evoked Potential with Diazepam Sedation / 대한마취과학회지

BACKGROUND: P300 component of the long latency auditory evoked potentials (LLAEPs) provides information on conscious and cortical funtion. The P300 wave occures only for stimuli that somehow capture the patients attention. Therefore LLAEPs implys a degree of cognitive processing. We studied sedation scale and P300 wave to determine if LLAEPs could be utilized as electrophysiologic predictors of sedation. METHODS: The P300 component of LLAEPs from vertex was recorded from 10 ASA physical status I and II patients undergoing elective surgery while they listened via headphones to a series of clicks which were interrupted unpredictably by a tone burst (2 KHz) before and after diazepam 0.04 mg/kg and 0.08 mg/kg IV. The patients were asked to concentrate on the clicks and to press a button whenever they detected a 2 KHz tone. And sedation scale also was measured. RESULTS: Amplitude of P300 was decreased and latency of P300 was increased in a dose-dependent manner with IV diazepam. Amplitude was greatest and latency was shortest in awake. And sedation scale also was increased according to increased IV diazepam adminstration. CONCLUSIONS: Both amplitude and latency may be highly related to the sedation scale with progressively increasing dose of diazepam. Therefore we conclude that P300 component of LLAEPs can be utilized as an electrophysiologic predictor of awareness and sedation.