Masui. The Japanese journal of anesthesiology
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Monosynaptic reflex responses (MSRs) in the isolated spinal cord of newborn rats were elicited in the ventral root by stimulation of the ipsilateral dorsal root. MSRs were considered to be mediated by non-NMDA class glutamate receptors. We studied the depressant effects of halothane, isoflurane, enflurane, and sevoflurane on MSR amplitudes as a function of anesthetic concentration comparing with MAC value of each anesthetics. ⋯ Concentration-response curves for MSR amplitudes were constructed and the concentrations which produced a half-maximum inhibition (IC50) were 0.56, 0.65, 0.97 and 1.18 mM for halothane, isoflurane, enflurane, and sevoflurane, respectively. These IC50 values correlated well with those of MAC values (r = 0.999, P < 0.001) obtained from adult rats in an in vivo condition. The MSR response in the isolated spinal cord of newborn rats is considered as a useful model for analysis of potency of volatile anesthetics.
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We investigated the usefulness of nasal/oral discriminate sampling system (NODSS) that had been developed recently in order to obtain the accurate end-tidal carbon dioxide (PET(CO2)) from a spontaneously breathing patient through a nomal airway. Fifty patients were monitored using a capnograph with NODSS following extubation in the postanesthesia unit. PET(CO2) data were collected by means of nasal, oral or nasal/oral sampling. ⋯ Furthermore, the mean (PaCO2 - PET(CO2)) gradient was 4.98 mmHg in patients aged over 60, while it was 2.02 mmHg in patients aged under 60, suggesting that PET(CO2) could not be a good index in elderly people. There was no significant difference in the mean (PaCO2 - PET(CO2)) gradient among different methods of anesthesia. In conclusion, NODSS was useful in determining PET(CO2) more accurately and estimating PaCO2 precisely when used in relatively young people by selective nasal or oral sampling.
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We reported 3 cases of sudden syncope during saddle block under sitting position. Patients were healthy and had no history of fainting. Syncope occurred following hypotension and bradycardia during difficult lumbar dural punctures under sitting position. ⋯ The first sign of syncope was hypotension and bradycardia due to cardiac C-fiber reflex. How to prevent this NCS under saddle block are as follows; 1. vigorous search for history of syncope, 2. pay attention to the patients during spinal tap, 3. skillful technique in spinal tap, and 4. proper premedication including anticholinergic agents. Treatments include 1. changing position to supine, 2. elevation of both legs to increase ventricular end-diastolic pressure, and 3. use of vasopressors including phenylephrine.