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Query: UMLS:C0085383 (hypocapnia)
 1,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a prospective study of 225 consecutive pediatric patients who required sedation for CT imaging, we monitored oral and nasal air flow, transcutaneous oxygen saturation, and cardiac rate and rhythm before and after the administration of IV Nembutal. In addition, the first 50 patients in this series had blood pressures mechanically monitored at 1-min intervals. There was no significant change in the cardiac rate, rhythm, or blood pressure in any patient. Seventeen episodes (7.5%) of transient oxygen desaturation to 80% of baseline or less occurred after sedation. The patterns of oxygen desaturation in this series can be explained by the following mechanisms: (1) hyperventilation leading to hypocapnia with resultant loss of the CO2 stimulus of respiration (12 patients); (2) upper airway obstruction from pharyngeal muscle relaxation (three patients); (3) a shift in sensitivity of CNS CO2 receptors (one patient); and (4) central apnea (one patient). Oxygen desaturation normalized spontaneously in 14 patients. In two patients, oxygen saturations returned to normal after modification of head position to optimize airway patency. In one patient, mild stimulation was required to interrupt transient apnea. All but one patient in whom desaturation occurred showed oxygen desaturation within the first 5 min after IV sedation. At The Children's Hospital of Denver, IV Nembutal has been used in over 870 pediatric patients. No patient required resuscitation, intubation, or assisted ventilation. Only one patient required prolonged observation, and one patient demonstrated an idiosyncratic hyperactive response. The sedation failure rate was less than 1%. The average dose of sedation was reduced when compared with IM Nembutal because the rapid onset of activity after IV administration allowed titration of dose to patient response.
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PMID:IV Nembutal: safe sedation for children undergoing CT. 326 31

A technique is described for the chronic measurement of cerebral blood flow in conscious, unrestrained rodents, utilizing laser doppler flowmetry (LDF) removably coupled to an optical fiber permanently implanted into brain tissue by established stereotaxic procedures. Changes in relative blood flow in response to a range of pharmacological and behavioral challenges were measured in the hippocampus (HBF) and striatum (StBF) 24-72 h and up to 28-32 days after surgical implantation of the optical fiber. Intraseptal microinfusion of L-glutamate in artificial cerebrospinal fluid 48-96 h and 28-32 days after surgery increased HBF. Pentobarbital (Nembutal) and urethane anesthesia decreased HBF. On the day of euthanasia under urethane anesthesia, HBF was demonstrated to be responsive to alteration of blood CO2 via hyper/hypocapnia, and autoregulation was demonstrated in response to hypovolemic hypotension. In behavioral experiments, blood flow was found to increase with activity and locomotion, as well as during paradoxical (PS) and slow-wave sleep (SWS). The greatest increase in CBF was measured during PS. Although basal levels of blood flow were similar between regions, the increase in blood flow during PS was greater in the hippocampus. This simple procedure enables real-time measurement of qualitative changes in regional cerebral blood flow during behaviors in conscious, unrestrained animals. The observation that constancy of measurements was obtained for 1 month enables within-subject analysis in longitudinal studies and reduces the number of animals required for investigations.
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PMID:Hippocampal and striatal blood flow during behavior in rats: chronic laser Doppler flowmetry study. 910 65