ABSTRACT
Objective To investigate the effects of different doses of dexmedetomidine on cerebral oxygen saturation and pulmonary shunt fraction in patients undergoing one-lung ventilation (OLV). Methods Sixty ASAⅠ-Ⅱpatients, aged 46-71 years, with body mass index (BMI)18-24 kg/m2 and scheduled for thoracotomy were randomly divided into three groups (n=20 each):high dose dexmedetomidine group (group D1), low dose dexmedetomidine group (group D2) and control group (group C). Dexmedetomidine 1μg/kg was infused in group D1 after anesthesia induction, and then a rate of 0.5μg·kg-1·h-1 was continuously infused. Dexmedetomidine 0.5μg/kg was infused in group D2 after anesthesia induction, and then a rate of 0.3μg · kg-1 · h-1 was continuously infused. Group C was received the equal volume of normal saline. Anesthesia was main?tained with propofol-remifentanil and intermittent iv boluses of rocuronium. Arterial and jugular venous blood samples were collected before anesthesia induction (T0), at 15 min after two-lung ventilation (T1), at 5 min (T2) and 30 min (T3) of OLV for blood gas analysis. Value of Qs/Qt was calculated and SctO2 was recorded at the same time. Results Compared with group C and group D2, Qs/Qt was decreased at T2 in group D1 (P<0.05). Qs/Qt was lower at T3 in group D1 and D2 than that of group C, and which was lower in group D1 than that of group D2 (P<0.05). In group C and group D1 a significant de?crease in SctO2 was observed at T2 and T3 compared to that at T0 and T1 (P<0.05). SctO2 was significantly higher at T2 and T3 in group D2 than that in group C and group D1 (P<0.05). Conclusion Dexmedetomidine given during OLV undergoing thoracotomy can improve oxygenation, decrease pulmonary shunt fraction and reduce the occurrence of low SctO2.
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Objective To evaluate the relationship between pharmacodynamics of sufentanil-induced respiratory depression and age factors. Methods Forty ASA Ⅰ or Ⅱ patients scheduled for elective abdominal surgery were randomly divided into 2 groups according to the age: young and middle-aged group (25-64 yr, group M) and elderly group (65-80 yr, group E). EC50 was determined by up-and-down sequential trail. The initial target effect-site concentration (Ce) of sufentanil was set at 0.40 and 0.35 μg/ml in group M and E respectively.Each time Ce decreased/increased by 10% in the next patient depending on whether or not the respiratory depression occurred. Respiratory depression was defined as VT ≤ 5 ml/kg, RR ≤ 8 bpm/min, SpO2 ≤ 94%,PET CO2 ≥ 55 mm Hg, and/or apnea ≥ 15 s. Results The EC50 and 95 % confidence interval of sufentanil causing respiratory depression were 0.61 (0.54-0.70) μg/ml and 0.41 (0.38-0.45) μg/ml in group M and E respectively with the significant difference. Conclusion The efficacy of sufentanil-induced respiratory depression is related to age factors and the elderly patients are more sensitive to sufentanil-induced respiratory depression.
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Objective To investigate the changes in the expression of nerve growth factor (NGF) and brain-derived neurotrophic (BDNF) in the dorsal root ganglion (DRG) and spinal dorsal horn following peripheral inflammatory hyperalgesia induced by formalin injected into the plantar region of the right hindpaw in rats. Methods Twenty-four adult SD rats weighing 250-400 g were studied. Peripheral inflammatory hyperalgesia was induced by an intraplantar injection of 5% formalin into right hindpaw. The animals were randomly divided into 4 groups (n=6 in each group), group A:control; group B:2 h after formalin injection; group C:24 h after formalin injection and group D: 48 h after formalin injection. Pain response was recorded. The expression of NGF and BDNF in the inflamed skin, DRG and spinal dorsal horn was detected using immuno-histochemistry technique and image analysis method. Results There were significant bi-phasic nociceptive responses induced by intraplantar injection of formalin in rats. The expression of NGF started to increase 2 h after injection, in the inflamed skin, ipsilateral DRG and dorsal horn neurons and reached the peak level at 24 h after injection. The expression of BDNF in ipsilateral DRG and dorsal horn neurons was unchanged 2 h after injection and started to increase at 24 h after injection. There was a positive correlateion between the expression of NGF and BDNF in ipsilateral DRG neurons.Conclusion NGF is not only an important transmitter in the peripheral mechanicsm of inflammatory pain but also involved in central sensitization through facilitating expression of BDNF in dorsal horn neurons.
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Objective To assess the efficacy of ropivacaine in combination with different doses of sufentanil for epidural anesthesia in patients undergoing hysterectomy. Methods Eighty ASA Ⅰ or Ⅱ patients aged 30-55 yrs weighing 40-70 kg undergoing elective hysterectomy were randomly divided into 4 groups ( n = 20 each) : ropivacaine group (R) and 3 ropivacaine-sufentanil groups (R-S1-3). The patients were unpremedicated. ECG, BP, HR and SpO2 were monitored during ansthesia. Each patient received an epidural catheter placed at L2,3 interspace. After correct placement of epidural catheter was confirmed 0.75% ropivacaine 13 ml and normal saline (NS) 2 ml were given through epidural catheter in group R whereas in the 3 R-S groups 0.75% ropivacaine 13 ml and sufentanil 10 (R-S1), 20 (R-S2) or 30 (R-S3) ?g in NS 2 ml were injected into epidural space. BP, HR and SpO2 were recorded every 3 min. The onset time, upper spread and duration of sensory block; onset and duration of motor block (Bromage scale); degree of abdominal muscle relaxation; level of sedation (OAA/S scale); anesthetic efficacy and side-effects were recorded. The dose-response curve constructed by probit regression analysis was established to calculate ED50 and ED95. Results The onset time, the time needed to reach the highest sensory level were significantly shorter and the duration of sensory block was significantly longer in the 3 R-S groups than in R group ( P