Effects Of Adjuvant Small Tidal Volume IPPV For Nondependent Lung On Oxygenation When One Lung-ventilation In Old Patients Undergoing Thoracic Esophagectomy

Objective: To investigate the effect of small tidal volume fornondependent lung on oxygenation and whether it disturbs the operation whenone lung-ventilation in old patients undergoing thoracotomy.Methods: Sixty patients of both sexes,aged60～75y and whose BMIwas between18.5～24in ASA Ⅰ～Ⅱwere scheduled for thoracicsurgery,whose heart function and lung function did not have obviousabnormality.The patients did not have anemia and other diseases of bloodsystem,did not have chemotherapy and radiotherapy.The patients wereattracted by esophageal cancer who were in charge of surgeries in the samegroups and their operations were in the left thorax.They were allocatedrandomly into two groups:Intermittent posititve-pressure veitilation(IPPV)group and control group.The upper limb venous access was foundedafter entering operation room,then they were given with atropine0.3mg andmidazolam0.05mg/kg30min before operation.And the patients were insusedwith15ml/kg/h Lactated Ringer solution.The Electrocadiogram (ECG),Saturation of Pulse Oximetry (SpO2), Blood Pressure (BP), Central VenousPressure (CVP),Ppeak,Pplat and PETCO2were monitored with IntelliVueMP50multifunctional monitor.Anesthesia induction was with Fentanyl2～4μg/kg,Etomidate0.2～0.3mg/kg,Cisatracurium0.3mg/kg after theirconsciousness disappearing. The left-sided double lumen endobronchial tubewas inserted after Cisatracurium being given.And the intubation were done bythe same skillful anesthetist.Correct positioning was verified by fiberopticbronchoscopy.During operation we used intravenous-inhalational anesthesiawith Sevoflurane(1～3%) and Remifentani（l0.5～1μg/kg/min）.The BispectralIndex was monitored and it’s value maintain between40～60. Cisatracurium of0.05mg/kg was given every half an hour to maintain muscle relaxation.Thepatients of two groups were ventilated with Datex-Ohmeda7100anaesthesiamachine, and the oxygenflow was1L/min.During two lung ventilation,therespiration parameters were setted:Tidal Volume8ml/kg,RespiratoryFrequency12times/min and Inspiration and Expiration ratio1：2.During onelung ventilation,the respiration parameters were setted:Tidal Volume6ml/kg,Respiratory Frequency15～17times/min,Inspiration and Expirationratio1：2.The bronchial tube of operation side lung in control group opened inthe air directly.The bronchial tube of Operation side lung in experimentalgroup was connected with Datex-Ohmeda7100Ventilator and therespiration parameters were setted:Tidal Volume1ml/kg,RespiratoryFrequency15times/min,and Inspiration and Expiration ratio1∶2,theoxygenflow was1L/min.We used conventional fluid infusion and adjusted thedepth of anesthesia in time to maintain hemodynamic smoothly, the amplitudeof variation of mean arterial pressure and heat rate was less than20%of thebasic value.During operation, urine volume was more than1ml/kg/min.ThepH,arterial partial pressure of oxygen(PaO2),artery partial pressure ofCO2(PaCO2),Alveolar-arterial oxygen pressure difference(A-aDO2) weremeasured by Cabs b123blood-gas analyzer at five timing:when beforeanesthesia and breathing air (T0)，two-lung ventilation lying on right sidefor10min (T1), one-lung ventilation lying on right side for15min(T2),30min(T3),45min(T4),and when the operation ending with two-lungventilation (T5).In addtion to those datas, the Heart Rate (HR),Saturation ofPulse Oximetry(SpO2)， Mean Blood Pressure(MBP),Central VenousPressure(CVP) were written at every time-point above.Results:There was no significant differences in two groups with respectto age, gender,height,weight,hemoglobin,PaO2before anesthsia, FVC,FEV1/FVC(%), DLCO,the duration of surgery,the duration of OLV(one lungventilation),fluid volume and urine volume（P>0.05）.No significant differences in the two groups were found inpH,Pao2,PaCO2,A-aDO2,HR,Mean Blood Pressure(MBP),Central Venous Pressure (CVP)（P>0.05）at T0and T1in IPPVgroup compared with controlgroup.There was significant increase with respect to PaO2（P<0.01）,andsignificantly decrease with respect to A-aDO2（P<0.05）and HR（P<0.05）in IPPV group at T2-4compared with control group.No significant differencesin the two groups were found in pH,Pao2,PaCO2,Mean BloodPressure(MBP),Central Venous Pressure (CVP（)P>0.05）in IPPV group at T2-4compared with control group. PaO2was significantly increased at T1comparedwith the baselines at T0(P<0.01).PaO2was significantly decreased at T3compared with the baselines at T0(P<0.05) in control group and HR wassignificantly increased at T3compared with the baselines at T0(P<0.05) incontrol group,but not in IPPVgroup.And A-aDO2was significantly increasedat T1-5compared with the baselines at T0(P<0.05) in the two groups when theycompared with themselves.Compared with control group at T5，no significant differences were found inpH,Pao2,PaCO2,A-aDO2,HR,Mean Blood Pressure(MBP),Central VenousPressure (CVP)（P>0.05）in IPPVgroup.Conclusion:For patients undergoing thoractomy,it can increase Pao2canimprove the patients’ oxygenation;it does not disturb the operation and thepatients’ hemodynamics, when we put small tidal volume as VT=1ml/kg IPPVto nondependent lung during one lung-ventilation.