Articles: reflex-drug-effects.
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Randomized Controlled Trial
Effect of increased body mass index and anaesthetic duration on recovery of protective airway reflexes after sevoflurane vs desflurane.
Increased BMI may increase the body's capacity to store potent inhaled anaesthetics, more so with more soluble agents. Accordingly, we asked whether increased BMI and longer anaesthesia prolonged airway reflex recovery. ⋯ Prolonged sevoflurane administration and greater BMI delay airway reflex recovery. The contribution of BMI to this delay is more pronounced after sevoflurane than desflurane.
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Randomized Controlled Trial
The effect of ketamine and nitrous oxide on the human pupillary light reflex during general anesthesia.
The neurotransmitters and receptor types involved in the afferent arm of the human pupillary light reflex are unknown. We hypothesized that the pupillary light reflex is mediated in part by NMDA receptors and that it would be depressed by the NMDA antagonists, nitrous oxide and ketamine. To study this question, sixteen patients received general anesthesia with desflurane, fentanyl, and muscular relaxation with rocuronium. ⋯ Heart rate, pupil size, and blood pressure were unchanged by the drugs when compared to the control groups. We conclude that the two NMDA antagonists ketamine and nitrous oxide depress the human pupillary light reflex during general anesthesia whereas other monitored parameters were either unchanged or paradoxically elevated by the drugs. These findings present evidence that glutamate NMDA receptor activation is involved in generating the human pupillary light reflex.
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Randomized Controlled Trial
Cardiovascular reflex responses to temporal reduction in arterial pressure during dexmedetomidine infusion: a double-blind, randomized, and placebo-controlled study.
The low and moderate doses of dexmedetomidine reduce arterial pressure and heart rate (HR), suggesting attenuation of sympathetic activity and dominance of cardiac-vagal activity. These autonomic responses under dexmedetomidine sedation may attenuate cardiovascular reflex responses to temporal reduction in arterial pressure, inducing a severe hypotension. We therefore investigated the effects of dexmedetomidine on cardiovascular reflex responses to temporal reduction in arterial pressure induced by the thigh cuff method. ⋯ The present results indicated that dexmedetomidine weakens arterial pressure preservation and HR responses after thigh cuff deflation, suggesting attenuated cardiovascular reflexes. Therefore, it must be cautioned that dexmedetomidine can lead to further and sustained reduction in arterial pressure during transient hypotension induced by postural changes, haemorrhage, and/or other stresses.
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Anesthesia and analgesia · May 2009
Randomized Controlled Trial Comparative StudyDose-dependent suppression of the electrically elicited stapedius reflex by general anesthetics in children undergoing cochlear implant surgery.
Cochlear implants stimulate the auditory nerve to enable hearing. Determining appropriate upper and lower limits of stimulation is essential for successful cochlear implantation. The intraoperative evoked stapedius reflex threshold (ESRT) and evoked compound action potential (ECAP) are commonly used to determine the limits of implant stimulation. In this study, we evaluated the dose-related effects of sevoflurane, desflurane, isoflurane, and propofol on the intraoperative ESRT and ECAP. ⋯ Volatile anesthetics suppress the stapedius reflex in a dose-dependent manner, suggesting that ESRT measurements acquired during volatile anesthesia will overestimate the maximum comfort level, which may cause discomfort postoperatively and adversely affect the child's adaptation to the implant. We advise against the use of volatile anesthetics for measurement of the stapedius reflex threshold during cochlear implant surgery.
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Neurogastroenterol. Motil. · May 2009
Randomized Controlled TrialInfluence of ghrelin on the gastric accommodation reflex and on meal-induced satiety in man.
Ghrelin increases gastric tone in the fasting state and enhances gastric emptying in gastroparesis. The aims of the study were to evaluate the effect of ghrelin on postprandial gastric tone and on meal-induced satiety in health. Ten healthy volunteers underwent a barostat study on two occasions. ⋯ Pressures inducing perception or discomfort during postprandial gastric distentions were not altered. During satiety testing, ghrelin did not alter nutrient volume ingested till maximal satiety (637.5 +/- 70.9 vs 637.5 +/- 56.2 mL, ns). Ghrelin administered during the meal significantly inhibits gastric accommodation in health, but this is not associated with early satiation.