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Objective To evaluate the effects of dexmedetomidine (DEX) on cell apoptosis induced by endoplasmic reticulum stress and c-Jun N-terminal kinase (JNK) pathway during one-lung ventilation (OLV) in rats.Methods Sixty male Sprague-Dawley rats were randomly allocated into 6 groups (n =10 each):sham operation group (Sham group),OLV group,OLV + atipamezole (α2 receptor antagonist) group (AD group),OLV + atipamezole + DEX group (DEX+AD group),OLV + low-dose DEX group (DEX-L group) and OLV + high-dose DEX group (DEX-H group).The animals were anesthetized with 10％ chloral hydrate 4.5 ml/kg,tracheostomized and mechanically ventilated.Bilateral lungs were ventilated for 2.5 h in Sham group.The right lung was ventilated for 2.0 h followed by 0.5 h two-lung ventilation in OLV group.In DEX-L and DEX-H groups,DEX was infused intravenously for 1 h at a rate of 2.5 μg · kg-1 · h-1 and 5.0 μg · kg-1 · h-1,respectively,starting from 1 h prior to OLV.Atipamezole 250 μg/kg was injected intravenously at 1 h prior to OLV in AD group.Atipamezole 250 μg/kg was injected intravenously at the onset of DEX infusion (5.0 μg · kg-1 · h-1) in DEX+AD group.The rats were sacrificed and left lungs were removed for determination of weight to dry lung weight ratio (W/D),cell apoptosis in lung tissues (by TUNEL),and expression of glucose-regulated protein 78 (GRP78) mRNA and protein,JNK mRNA and phosphorylated JNK (p-JNK) protein (by RT-PCR and Western blot).Pathological changes of lungs were examined and the injured alveolus rate (IAR) was counted under light microscope.The changes in ultrastructure of lung tissues were observed under transmission electron microscope.Apoptosis index (AI) was calculated.Results W/D,AI and IAR were significantly higher in OLV,AD and DEX+AD group than in Sham group,while lower in DEX-L and DEX-H groups than in OLV,AD and DEX+AD groups.The pathological changes of the structure of lung tissues were observed in OLV,AD and DEX+AD groups,while the pathological changes were significantly alleviated in DEX-L and DEX-H groups.In OLV,AD and DEX + AD groups,there was apoptosis in lots of pulmonary vascular endothelial cells and alveolar epithelial cells,while cell apoptosis was significantly reduced after administration of DEX.The expression of GRP78 mRNA and protein,JNK mRNA and p-JNK protein was significantly higher in OLV,AD and DEX+AD groups than in Sham group,and lower in DEX-L and DEX-H groups than in OLV,AD and DEX +AD groups.Conclusion DEX pretreatment can protect lungs during OLV,and inhibited JNK signaling pathway and reduced cell apoptosis induced by endoplasmic reticulum stress may be involved in the mechanism.
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Objective To investigate the effect of dexmedetomidine on the damage to the nonventilated lung in the patients undergoing one-lung ventilation (OLV).Methods Forty patients of both sexes, aged 18-64 yr, with body mass index of 18-25 kg/m2, of American Society of Anesthesiologists physical status Ⅱ or Ⅲ, scheduled for elective radical surgery for lung cancer under general anesthesia, were randomly divided into either control group (group C) or dexmedetomidine group (group D) with 20 in each group.After induction of anesthesia, the patients were tracheally intubated and mechanically ventilated.After correct positioning was confirmed by fiberoptic bronchoscopy, dexmedetomidine was infused for 20 min as a dose of 0.5 μg/kg, followed by an infusion of 0.5 μg · kg-1 · h-1 until the moment of tumor resection.The equal volume of normal saline was given in group C.Immediately after the beginning of OLV, at 60 min of OLV, and immediately after the end of OLV, the specimens of normal lung tissues around the tumor were obtained for microscopic examination of pathologic changes which were scored, and for determination of the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and heme oxygenase-1 (HO-1) by Western blot.Results Compared with group C, the pathological score was significantly decreased on the non-ventilated side immediately after the end of OLV, and the expression of HIF-1α and HO-1 in the lung tissues on the non-ventilated side was up-regulated in group D (P＜0.05).Conclusion Dexmedetomidine can mitigate the damage to the non-ventilated lung in the patients undergoing OLV, and the mechanism is associated with up-regulated expression of HIF-1α and HO-1.
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Objective To evaluate the correlation between stroke volume variation (SVV) and blood volume during one-lung ventilation (OLV).Methods Forty ASA Ⅱ male patients,aged 50-60 yr,with body mass index 20-25 kg/m2,scheduled for elective resection of esophageal cancer,were studied.Anesthesia was induced with fentanyl 4 μg/kg,propofol 2 mg/kg,and rocuronium 0.6 mg/kg.Double-lumen tube was inserted.Correct position was verified by fiberoptic bronchoscopy.The patients were mechanically ventilated (VT 8 ml/kg,RR 15 bpm,Ⅰ ∶ E 1 ∶ 2).6％ hydroxyethyl statch (HES) 130/0.4 was infused intravenously at a rate of 0.67 ml· kg-1 · min-1 starting from 30 min of OLV.SVV,cardiac output (CO),SV and cardiac index (CI) were monitored and recorded using the FloTrac/Vigileo (Edwards Lifesciences,USA) system before HES was infused and when the dose of HES reached 2,4,6,8,10 and 12 ml/kg.Spearman rank sum correlation coefficient was used to analyze the data.Results SVV was negatively correlated with the blood volume during OLV and the correlation coefficient was rSVV =-0.249.CI,CO and SV were positively correlated with the blood volume during OLV and the correlation coefficients were rCO =0.570,rSV =0.552 and rCI =0.550,respectively.Conclusion SVV is poorly correlated with the blood volume during OLV and can not reflect the blood volume accurately.
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Objective To evaluate the accuracy of stroke volume variation (SVV) in monitoring blood volume during one-lung ventilation in patients undergoing thoracoscopy operation. Methods Twenty-two ASA Ⅰ or Ⅱ patients ( 12 male, 10 female) aged 18-60 yr undergoing thoracoscopy operation under general anesthesia were studied. Anesthesia was induced with midazolam, sufentanil, propofol and rocuronium and maintained with TCI of propofol and remifentanil and intermittent iv boluses of vecoronium. Robertshow double-lumen endobronchial tube was inserted. Correct position of the tube was verified by fiberoptic bronchoscopy. The patients were mechani40 mm Hg. Radial artery was cannulated and connected to FloTrac pressure transducer and Vigileo monitor. A loading dose of 6% HES 5 ml/kg was infused over 10 min. MAP, HR, CO and SVV were recorded before and at 3 min after loading dose. The change rate of SVV (SVV) and CI (△CI) were calculated. Increase in CI by 11% was considered effective volume expansion. The ROC curve for SVV in determining the volume expansion efficacy was plotted. The area under the curve for SVV and 95% confidence interval were calculated. Results (1) CO were significantly increased while SVV decreased after a loading dose of HES. (2) During two-lung ventilation 12 patients responded to the 6% HES loading dose.SVV correlated with△CI ( - 0.710, P ＜ 0.05). The volume expansion efficacy was determined by SVV 11.5 % (sensitivity = 82 %, specificity = 92 % ). The area under the curve for SVV and 95% confidance interval were 0.880 (0.580-0.987). (3) During one-lung ventilation 11 patients responded to the 6 % HES loading dose. SVV correlated with CI ( - 0.668 , P ＜ 0.05). The volume expansion efficacy was determined by SVV 9.5 % ( sensitivity = 77 %, specificity = 63 % ). The area under the curve for SVV and 95% confidance interval were 0.971 (0.917-1.024). Conclusion One-lung ventilation does not alter the ability of SVV in monitoring blood volume in patients undergoing thoracoscopy operation.
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Objective To study the changes of heart rate variability (HRV) and the effects of treatment with nasal continuous positive airway pressure (nCPAP) in elderly patients with sleep apnea/ hypopnea syndrome (SAHS). Methods SAHS patients and controls were examined by polysomnography(PSG) and dynamic cardiograph(DCG). Mean RR interval(Mean RRi), standard deviation of RR interval (SDRRi), low frequency(LF), high frequency(HF) and their ratio(LF/HF) were calculated. Results When compared with controls(847.9?113.8)ms vs (45.7?16.2) ms, there was significantly decrease in the Mean RRi and SDRRi in moderate, severe elderly patients and non-elderly SAHS patients(764.3?131.0)ms, (709.4?101.8)ms, (759.5?80.0)ms and (37.5?12.2)ms, (31.5?9.6)ms, (41.4?10.6)ms. There was statistical differences in LF, HF, and LF/HF between elderly and non-elderly severe SAHS (P
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Objective To determine the effect of of thoracic epidural block on arterial oxygenation and intrapulmonary shunt during one-lung ventilation(OLV).Methods Twenty-four ASA class I - Ⅱ patients undergoing prolonged periods of OLV during elective general thoracic surgery were divided into two groups: general anesthesia group(GA)(n=12) and general anesthesia + epidural block group(GE, n = 12). The patients were premedicated with only scopolamine 0.3mg. Radial artery was cannulated and Swan-Ganz catheter placed via right internal jugular vein under local anesthesia. Epidural block was performed at T7-8or T8-9 and a catheter was inserted and advanced in the epidural space cranially for 3.5-4 cm. General anesthesia was induced with propofol l.5mg?kg-1, fentanyl 3?g?kg-1 and vecuronium 0.1 mg?kg-1. Right or left-sided double-lumen endobronchial tube was placed blindly and the correct position was determined by a combination of unilateral clamping and unclamping and auscultation of the lungs. In GA group anesthesia was maintained with continuous infusion of propofol (150-200 ?g?kg-1?min-1 ) and intermittent IV boluses of fentanyl and vecuronium. BIS was maintained at 45-50. In GE group anesthesia was maintained with infusion of propofol(80 - 120 ?g?kg-1?min-1 ) and epidural block (a loading dose of 0.5% ropivacaine 7-9ml followed by epidural infusion of 0.5% ropivacaine 3-5 ml?h-1) .The patients were mechanically ventilated. VT = 8-10 ml?kg-1, FiO2 = 1, I: R = 1:1.5 and respiratory rate was adjusted to maintain PET CO2 at 35-45 mm Hg. During OLV the above parameters were maintained. ECG, HR, MAP, MPAP, CVP, continuous cardiac output, BIS and TOP were continuously monitored during operation. Blood samples were taken from radial artery and S-G catheter for blood gas analysis at following intervals: (1) during spontaneous breathing when the patients was a wake (baseline); (2) when the patient was placed in lateral position and the two lungs were being ventilated for 30 min(TLV 30 I) ; (3) 5,15, 30 and 60 minduring the course of OLV; (4) the two lungs were ventilated again for 30 min (TLV 30II) andQs/Qt was calculated. Results Venous admixture increased significantly after induction of anesthesia and during mechanical ventilation and increased further during OLV as compared with the baseline(P