The Correlation Between P_ETCO₂and PaCO₂during One-lung Ventilation

The correlation between P_ETCO₂and PaCO₂during One-lung ventilationObjective: To investigate correlation and clinical significance betweenarterial partial pressure carbon dioxide （PaCO₂） and end expiratory partialpressure of carbon dioxide (P_ETCO₂) during One-lung ventilation in theoperation of lung cancer.Method:20patients, ASA I^II, male in15cases, female5cases, aged35⁶5years old, weighing45⁸0kg, height1.55¹.80, left open thoracic13cases, right open thoracic7cases, are scheduled for the operations of lungcancer. Preoperative tests and chemical examination are normal,exclusioncriteria were severe disease of Respiratory system or circulation system,without histories of hepatic or renal diseases, The patients were premedicatedwith intramuscular atropine0.5mg before anaesthesia, after entering operatingroom, monitoring of ECG、HR、SpO₂、NIBP and IBP are carried out on them,Patients with oxygen mask breathing （4L/min） were performed induced generalanesthesia by intravenous injection with midazolam0.02-0.04mg·kg^-1、sufentanyl0.3⁰.6ug·kg^-1、atracurium0.15mg·kg^-1 and etomidate0.3mg·kg^-1in turn. The Mallinckrodt double-lumen endobroncheal tubes （DLTs） wereinserted orally under direct vision. After the patients were intubated and placedin the lateral position, fiberoptic bronchoscope （FOB） were used to determinethe precise positions of the DLTs, tracheal intubation is followed byvolume-controlled ventilation （VCV）. Prime setting: breathing rate （f）=12times·min-1, VT=8-10mL·kg^-1, fresh gas flow=2.0L·min-1. Anesthesia wasmaintained with propofol （80-100μg/kg/min） and remifentanil （0.05-0.2μg/kg/min） intravenously, supplemental atracurium was use for maintenance during the operation, According to the change of BP、HR to adjust the drugdose. After the tracheal intubation keep the patients supine position for doublelung ventilation ten minutes then keep them lateral position for one lungventilation. Adjusting f and VT according to SpO₂and partial pressure ofcarbon dioxide in endexpiratory gas (P_ETCO₂),to maintain SpO₂98%～100%,P_ETCO₂30-40mmHg.After the intubation of the patients, BP、HR、SpO₂、Ppeak、Vt、MV andP_ETCO₂were monitored continuously by Multifunctional vital signs monitor.Measured the value of P_ETCO₂and PaCO₂10min following TLV and10min,30min,60min,90min,120min following OLV.Statistical treatment is completed with SPSS13.0package. Measurementdata is expressed by mean（X）±standard deviation（s）, Count data is usinglinear related and Regression analysis and t test, P<0.05is considered asstatistical significance.Result:The statistical analysis show that there was a significant positivecorrelation between P_ETCO₂and PaCO₂TLV（r=0.870, p<0.05） and before60min during OLV（r=0.889,0.921, p<0.05）.Conclusion:1. there was a well correlation between P_ETCO₂and PaCO₂before60minduring OLV.2. After60min during OLV, P_ETCO₂could not reflect the change ofPaCO₂accurately.3. PaCO₂is needed to monitor intermittent to correct P_ETCO₂during OLVfor a long time.