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L S Sun

Publications and source records attributed to L S Sun.

38 records · Page 3Linked to original sources
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Heart rate variability in neonatal rats after perinatal cocaine exposure.

Pregnant rats received saline once daily (Control QD) or twice daily (Control BID), cocaine 2 mg/kg IV daily (COC QD) or twice daily (COC BID) throughout gestation beginning on gestational day 4. The treatment was continued in nursing mothers until postnatal day 7. All studies were performed in their offsprings on postnatal days 1 and 7. An age-dependent increase in heart rate was observed from D1 to D7 in all four groups of animals. Cocaine exposure significantly increased heart rate in the once daily treatment group on D1 and D7. In contrast, twice daily cocaine exposure did not alter heart rate. Maturational changes in heart rate variability (HRV) were also documented. Low-frequency (LF: 0.25-0.8 Hz) power of HRV is a marker of both sympathetic and parasympathetic influences. and high-frequency (HF: 0.8-2.4 Hz) power is a marker of efferent vagal activity. Total power (TP) is the sum of LF and HF. TP, normalized units of LF (LF as percent of TP), and normalized HF power decreased from D1 to D7 in all groups. Cocaine treatment affected both LF and HF powers and there was an interaction between cocaine treatment and age for both LF and HF. Although LF/HF ratio decreased from D1 to D7 in both groups of control animals. LF/HF did not change from D1 to D7 in either cocaine-treated group. Thus, cocaine exposure significantly attenuated the age-dependent change in LF/HF. Our results indicated that there were normal developmental changes in HRV consistent with continued postnatal development of autonomic nervous system. Perinatal cocaine exposure appeared to modify these changes. The specific autonomic mechanism for the cocaine effect may be a decline in parasympathetic activity and a concomitant change in sympathetic activity.

Animals↗
PubMedDate not supplied

Preemptive analgesia in children. Does it exist?

BACKGROUND AND OBJECTIVES: Preemptive analgesia has been evident in animals, but few adult human studies exist demonstrating this concept exist, and there are fewer still in children. Caudal epidural blocks with local anesthetics are often placed for postoperative analgesia in children. This study evaluated whether these blocks are more effective when placed prior to surgical incision. METHODS: Children aged 1-6 years and ASA I and II (n = 51), undergoing elective herniorrhaphy, orchidopexy, or circumcision were randomly assigned to receive a caudal epidural block with 0.6 mL/kg of 0.25% bupivacaine with 1:200,000 epinephrine, either before incision (n = 28) or after surgery (n = 23). In all patients, anesthesia was induced and maintained with oxygen, nitrous oxide, and halothane, and caudal epidural blocks were placed. Postoperative pain was scored by a blinded observer using a Faces Pain Scale in the recovery room and was also assessed at home by the parents. Analgesic requirement during the 24-hour period was recorded. RESULTS: The Faces Pain Scale scores and analgesic requirements did not differ between the groups, either in the recovery room or at home (P > .05). CONCLUSIONS: Although preemptive analgesia has been successfully demonstrated in some earlier clinical studies, our results indicate that pre- and postincisional caudal epidural blocks with 0.25% bupivacaine were equally effective in children.

Abdomen↗