Interference with processed electroencephalographic recording by facial nerve stimulation.
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Electric Stimulation↗
Biomedical subjects
H S Chadwick
Publications and source records attributed to H S Chadwick.
The neurologic effects of thiopental therapy following experimental cardiac arrest in cats.
To define the utility of high-dose barbiturate therapy following an episode of complete global cerebral ischemia, we investigate the effects of 60 mg/kg of thiopental given to cats five minutes after resuscitation from 12, 14, or 16 min of electrically induced ventricular fibrillation (VF). All aspects of the arrest, resuscitation, with post-arrest care were carefully controlled, with the EEG becoming isoelectric 20-25 s after the onset mean resuscitation time of 2.5 +/- 0.2 (SEM) min. For any given duration of VF, there were no differences (control vs thiopental) in any pre- or post-arrest parameters (blood pressure, blood gases, electrolytes, etc.) A total of 68 resuscitated cats were entered into various treatment and control groups, and all but one group received 20-24 h of post-resuscitation paralysis, mechanical ventilation, and ICU support before being extubated. Cats received an additional six days of aggressive nursing care, and daily examinations were performed with the assignment of a neurologic deficit score (NDS) between 0 (normal) and (brain dead). Autopsies were performed to determine the cause of death in animals which died before the end of the seven-day observation period. The early post-arrest period was marked by the occurrence of repetitive, rhythmic bursts of high-frequency electroencephalographic (EEG) activity (? seizures) in 38 per cent of control animals (16/42, all arrest times combined). Ten of these animals died as a result of severe neurologic injuries. By contrast, only 12 per cent of treated cats (3/26) developed similar EEG patterns (P less than 0.05) and there were no neurologic deaths in the thiopental groups. The differences in the incidence of neurologic deaths (control vs. thiopental) was significant (P less than 0.02). The change in overall mortality did not quite reach significance (36 per cent vs. 21 per cent), and treatment had no effect on the incidence of deaths due to cardiovascular causes (e.g., myocardial infarctions). In spite of the effects on mortality, treatment had no effect on the neurologic function of survivors (assessed by NDS). These findings suggest that thiopental improved survival rates by suppressing an unusual post-arrest EEG pattern (? anticonvulsant effect), but had no additional cerebral protective effects.
Animals↗
Sprotte needle for obstetric anesthesia: decreased incidence of post dural puncture headache.
BACKGROUND AND OBJECTIVES: Reports have emphasized the importance of spinal needle tip configuration in the development of post dural puncture headache (PDPH). METHODS: Charts from 366 consecutive obstetric patients receiving spinal anesthesia for labor, cesarean delivery, postpartum surgical procedures, or postpartum tubal ligations were reviewed retrospectively for evidence of PDPH in the five days after dural puncture. Spinal anesthesia was administered to these patients using 25-gauge Quincke (n = 74), 26-gauge Quincke (n = 160), or 24-gauge Sprotte (n = 132) spinal needles. RESULTS: The groups were well matched demographically. The incidence of PDPH in the three groups was 9%, 8%, and 1.5%, respectively. Half of the patients developing PDPH in each group were treated with an epidural blood patch. CONCLUSIONS: Our data indicate that the Sprotte spinal needle, with its non-cutting tip, results in a significantly lower (p less than 0.05) incidence of PDPH than Quincke cutting-tip needles of smaller gauge.
Anesthesia, Obstetrical↗
A comparison of postcesarean epidural morphine analgesia by single injection and by continuous infusion.
To assess the relative efficacy and incidence of side effects of a single injection versus a continuous infusion of epidural morphine sulfate (MS) in the postcesarean population, the authors report a prospective, randomized, double-blind study. Thirty-one patients received either a 5-mg MS bolus and subsequent saline infusion (n = 13) or a 2.6-mg MS bolus and subsequent MS infusion at 0.1 mg/hour (n = 18), such that after 24 hours both groups had received a total MS dose of 5 mg. No statistically significant differences were found between the two groups in overall satisfaction with analgesia, verbal pain scores, level of activity, need for supplemental opioids, or incidence of sedation during the 24-hour study period. The authors conclude that in this population, continuous epidural morphine infusion offers no obvious advantage over single morphine bolus therapy. However, the theoretical merits of continuous opioid infusion therapy are discussed.
Analgesia, Epidural↗