Beginning Of One-lung Ventilation Research Articles

Positive effects of low-dose S-ketamine on preventing myocardial injury after thoracoscopic lobectomy in patients aged 70 to 85

ObjectiveTo investigate the effects of low-dose S-ketamine on marker of myocardial injury (BNP, hs-cTnT and HFABP) after thoracoscopic lobectomy in patients aged 70 to 85.MethodsOne hundred patients (four cases excluded) aged 70–85 years, with body mass index 18–24 kg·m−2 and American Society of Anesthesiologists physical status II–III, scheduled for elective lobectomy from April 2022 to April 2023, were selected. The patients were divided into two groups by a random number table method, namely, the low-dose S-ketamine combined with GDFT group (group S) and the control group (group C), with 48 cases in each group. In group S, a low dose of S-ketamine (0.2 mg/kg) was given 1 min before intubation, and the maintenance dose was 0.12 mg·kg−1·h−1. Fluid therapy, guided by cardiac index (CI), changes in stroke volume (△SV), and other dynamic indicators, was used for rehydration during the operation. Group C was given the same amount of normal saline (0.2 mg/kg) 1 min before intubation, and the same rehydration therapy was adopted during the operation. The mean arterial pressure (MAP) and heart rate (HR) of the two groups were observed and recorded immediately after entering the operating room (T0), immediately after intubation (T1), immediately after the beginning of one-lung ventilation (OLV) (T2), immediately after the beginning of surgery (T3), immediately after the end of OLV (T4), and at the end of surgery (T5). The intraoperative fluid intake and output and the use of vasoactive drugs were recorded. The plasma levels of heart-type fatty acid–binding protein (HFABP), high-sensitivity troponin T (hs-cTnT), brain natriuretic peptide (BNP), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were recorded 24 h before operation and 24 and 48 h after operation. Visual analogue scale (VAS) pain scores at rest were recorded at 2 (V1), 6 (V2), 12 (V3), 24 (V4), and 48 h (V5) after operation, and the occurrence of myocardial ischemia during hospitalization was noted.ResultsCompared with group C, MAP was significantly higher at T1–T5 in group S (P < 0.05), and the plasma concentrations of IL-6, IL-8, TNF-α, BNP, hs-cTnT, and HFABP were significantly lower at 24 and 48 h after operation (P < 0.05). The VAS pain scores at 2, 6, 12, 24, and 48 h after operation, the number of effective patient-controlled intravenous analgesia (PCIA) compressions, and the total number of PCIA compressions within 48 h after operation were significantly decreased (P < 0.05). Compared with group C, The hospitalization days, and the incidence of postoperative myocardial ischemia in group S were lower (P < 0.05). There were no significant intergroup differences in urine volume, extubation time, the incidence of postoperative atrial fibrillation, bleeding volume, colloid infusion volume, total fluid infusion volume, and the incidence of rescue analgesia.ConclusionsLow-dose S-ketamine can reduce the levels of hs-cTnT, HFABP, and BNP in older patients after pulmonary lobectomy, which has a positive effect on preventing myocardial injury.Trial registrationThis study was registered on CHICTR (registration No. ChiCTR2300074475). Date of registration: 08/08/2023.

Effects of different positive end-expiratory pressure titrating strategies on oxygenation and respiratory mechanics during one- lung ventilation: a randomized controlled trial.

Positive end-expiratory pressure (PEEP) is widely used to reduce the risk of hypoxemia and atelectasis during one-lung ventilation (OLV); however, the optimal strategy for PEEP titrating remains unclear.The purpose of the study was to investigate the effects of different PEEP titrating strategies on oxygenation and respiratory mechanics during OLV. Patients undergoing thoracic surgery with general anesthesia were randomly allocated into five groups. In P0 group, PEEP was set to zero; in PLIP2 group, PEEP was set to 2 cmH2O plus the pressure of lower inflection point (LIP) of pressure-volume (P-V) curve; in PLIPS group, PEEP was titrated to achieve maximum static compliance from the averaged LIP pressure value; in groups PSTAT and PDYN, the incremental PEEP values were titrated to achieve maximum static compliance or maximum dynamic compliance from 4 cmH2O. Hemodynamic measurements, respiratory mechanics, and blood gas analyses were recorded at the beginning of OLV, OLV 15 min, OLV 30 min, OLV 45 min, and OLV 60 min. Also, the intrapulmonary shunt (Qs/Qt), physiological dead space to tidal volume ratio (VD/VT), and oxygenation index (OI) were calculated and compared. Seventy-five patients consented to participate in this study. Dynamic compliance, peak inspiratory pressure (PIP), and plateau inspiratory pressure (Pplat) increased after PEEP titration during OLV. PIP, Qs/ Qt, and OI showed no differences among groups. Group PDYN showed lower Pplat, lower driving pressure, and higher dynamic compliance when compared with zero PEEP group. The PEEP titrating strategy according to dynamic compliance can improve respiratory mechanics, whereas it has no significant effects on oxygenation, dead space ratio, and intrapulmonary shunt, suggesting that it is better during OLV for thoracic surgery.

Effects of apneic oxygen insufflation on oxygenation and intra-alveolar pressure during one lung ventilation

Objective To observe the effects of apneic oxygen insufflation (AOI) on the oxygenation and intra-alveolar pressure of patients with one lung ventilation (OLV). Methods Ninety patients undergoing open thoracotomy were enrolled, where 45 patients were divided into three groups according to a random number table: a control group (group A), a test 1 group (group B) and a test 2 group (group C), with 15 patients in each group; and another 45 patients were divided into three groups according to the pattern of double-lumen tubes: a 35 Fr group (group D), a 37 Fr group (group E), and a 39 Fr group (group F), with 15 patients in each group. During OLV, the non-ventilated lungs in groups A, B, and C were delivered with oxygen at a rate of 0, 3 and 5 L/min, respectively, and arterial blood samples were taken 1 min before OLV (T1), 30 min after the beginning of OLV (T2), and 60 min after the beginning of OLV (T3) for blood gas analysis, so as to calculate oxygenation index (OI), intrapulmonary shunt rate (Qs/Qt) and the satisfaction of surgeons towards collapsed lung. The intra-alveolar pressure at different oxygen flow rates (2-9 L/min) was measured in groups D, E and F after the beginning of OLV. Results OI decreased and Qs/Qt increased in groups A, B and C at T2 and T3 compared with those at T1 (P< 0.05). OI was remarkably higher in group B at T2 and higher in group C at T2 and T3 than those in group A, and Qs/Qt was significantly lower in group B at T2 and lower in group C at T2 and T3than those in group A (P<0.05). Compared with group B, group C presented remarkable increases in OI and significant decreases in Qs/Qt at T2 and T3 (P<0.05). The intra-alveolar pressure was lower in groups E and group F at different oxygen flow rates than that in group D (P<0.05); the intra-alveolar pressure was lower in group F at different oxygen flow rates than that in group E (P<0.05). Conclusions AOI at 5 L/min during OLV can maintain gas exchange to some extent in the alveoli, improve oxygenation and reduce Qs/Qt, which may be related to the intra-alveolar pressure produced by AOI in the operated lung. Key words: One lung ventilation; Apneic oxygen insufflation; Oxygenation index; Intra-alveolar pressure

Effect of lung protective ventilation on coronary heart disease patients undergoing lung cancer resection

Mechanical ventilation, especially large tidal volume (Vt) one-lung ventilation (OLV), can cause ventilator-induced lung injury (VILI) that can stimulate cytokines. Meanwhile, cytokines are considered very important factor influencing coronary heart disease (CHD) patient prognosis. So minimization of pulmonary inflammatory responses by reduction of cytokine levels for CHD undergoing lung resection during OLV should be a priority. Because previous studies have demonstrated that lung-protective ventilation (LPV) reduced lung inflammation, this ventilation approach was studied for CHD patients undergoing lung resection here to evaluate the effects of LPV on pulmonary inflammatory responses. This is a single center, randomized controlled trial. Primary endpoint of the study are plasma concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-10 and C-reactive protein (CRP). Secondary endpoints include respiratory variables and hemodynamic variables. 60 CHD patients undergoing video-assisted thoracoscopic lung resection were randomly divided into conventional ventilation group [10 mL/kg Vt and 0 cmH2O positive end-expiratory pressure (PEEP), C group] and protective ventilation group (6 mL/kg Vt and 6 cmH2O PEEP, P group; 30 patients/group). Hemodynamic variables, peak inspiratory pressure (Ppeak), dynamic compliance (Cdyn), arterial oxygen tension (PaO2) and arterial carbon dioxide tension (PaCO2) were recorded as test data at three time points: T1-endotracheal intubation for two-lung ventilation (TLV) when breathing and hemodynamics were stable; T2-after TLV was substituted with OLV when breathing and hemodynamics were stable; T3-OLV was substituted with TLV at the end of surgery when breathing and hemodynamics were stable. The concentrations of TNF-α, IL-6, IL-10 and CRP in patients' blood in both groups at the very beginning of OLV (beginning of OLV) and the end moment of the surgery (end of surgery) were measured. The P group exhibited greater PaO2, higher Cdyn and lower Ppeak than the C group at T2, T3 (P<0.05). At the end moment of the surgery, although the P group tended to exhibit higher TNF-α and IL-10 values than the C group, the differences did not reach statistical significance(P=0.0817, P=0.0635). Compared with C group at the end moment of the surgery, IL-6 and CRP were lower in P group, the differences were statistically significant (P=0.0093, P=0.0005). There were no significant differences in hemodynamic variables between the two groups (P>0.05). LPV can effectively reduce the airway pressure, improve Cdyn and PaO2, reduce concentrations of IL-6 and CRP during lung resection of CHD patients.Trial registration: The trial was registered in the Chinese Clinical Trial Registry.

Effect of continuous low- to medium-flow oxygen administration in non-ventilated lung on oxidative stress response of lung tissues during one-lung ventilation

Objective To evaluate the effect of continuous low- to medium-flow oxygen administration in non-ventilated lung on the oxidative stress response of lung tissues during one-lung ventilation (OLV). Methods Fifty-seven American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients, aged 50-64 yr, weighing 40-74 kg, scheduled for elective pulmonary tumorectomy, were divided into 2 groups using a random number table: control group (group C, n=29) and continuous oxygen administration group (group O, n=28). The patients were intubated with the double-lumen tube after induction of anesthesia.Correct position of the tube was verified with the fiberoptic bronchoscope.In group O, the F14 tube was placed at 2-3 cm beyond the carina of trachea in the non-ventilated lung at the beginning of OLV, and low- to medium-flow oxygen was continuously administered at 1-4 L/min with the fractional concentration of inspired oxygen set at 25%-37%.Blood samples were taken from the radial artery and internal jugular bulb at the beginning of anesthesia induction (T1) and 30 min, 1 h and 2 h of OLV (T2-4) for blood gas analysis.Lung tissues at the site 5 cm lateral to the tumor were taken immediately after resection of diseased tissues for determination of superoxide dismutase and malondialdehyde levels (by chemical colorimetry) and heme oxygenase-1 expression (by Western blot). Results Compared with group C, the partial pressure of arterial oxygen was significantly increased at T2-4, the partial pressure of arterial carbon dioxide was decreased at T2, 3, the partial pressure of venous oxygen was increased at T2, 3, the partial pressure of venous carbon dioxide was decreased at T2-4, the malondialdehyde level was decreased, and the expression of heme oxygenase-1 was up-regulated (P 0.05). Conclusion The mechanism by which continuous low- to medium-flow oxygen administration in non-ventilated lung exerts pulmonary protection is related to inhibiting oxidative stress responses of lung tissues during OLV. Key words: Respiration, artificial; Respiratory distress syndrome, adult; Oxidative stress

Effects of flurbiprofen axetil administered at different time points on oxygenation in patients undergoing one-lung ventilation

Objective To evaluate the effects of flurbiprofen axetil administered at different time points on oxygenation in the patients undergoing one-lung ventilation(OLV). Methods Ninety patients of both sexes, aged 45-64 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective thoracoscope-assisted pulmonary lobectomy, were assigned into 3 groups(n=30 each)using a random number table: control group(group C), preoperative administration group(group F1)and intraoperative administration group(group F2). Flurbiprofen axetil (10 mg/ml) and fat emulsion 10 ml were injected intravenously at 15 min before operation in F1 and C groups, respectively.Flurbiprofen axetil 10 ml was intravenously injected immediately after the beginning of OLV in group F2.At 15 min before operation(T1), 15 and 30 min of OLV(T2, 3), and 15 min after restoration of two-lung ventilation(T4), airway peak pressure(Ppeak)and dynamic lung compliance(Cdyn)were recorded, arterial blood samples were collected for blood gas analysis.The arterial oxygen partial pressure(PaO2)was recorded, and the oxygenation index(OI)and intrapulmonary shunt(Qs/Qt)were calculated.The concentrations of thromboxane B2(TXB2)and 6-keto-prostaglandin F1α(6-K-PGF1α)in serum were measured by enzyme-linked immunosorbent assay, and TXB2/6-K-PGF1α ratio was calculated.The development of interrupting OLV due to SpO2<90% and postoperative dyspnea, pulmonary infection, atelectasis and length of hospital stay were recorded. Results Compared with group C, PaO2 and OI were significantly increased, and Qs/Qt was decreased at T2, 3, the serum concentrations of TXB2 and 6-K-PGF1α were decreased, and TXB2/6-K-PGF1α ratio was increased at T2-4, the incidence of interrupting OLV was decreased(P 0.05). Compared with group F1, PaO2 and OI were significantly decreased at T2, 3, Qs/Qt was increased at T2, and the serum concentrations of TXB2 and 6-K-PGF1α were increased, and TXB2/6-K-PGF1α ratio was decreased at T2-4 in group F2(P 0.05). Conclusion Flurbiprofen axetil injected at 15 min before operation can significantly improve oxygenation and prevent the development of hyoxemia in the patients undergoing OLV, however, flurbiprofen axetil administered immediately after the beginning of OLV has no such effect. Key words: Flurbiprofen; Pulmonary gas exchange; Respiration, artificial

Hypoxia during one lung ventilation in thoracic surgery

Background. The technique of one lung ventilation (OLV) is used with the pur-pose of achieving isolation of the diseased lung being operated upon, using a double-lumen endobronchial tube. Thoracic surgi-cal procedures which are performed in the lateral decubitus position, nowadays could not be imagined without OLV. In spite of advantages regarding surgical exposure, OLV is associated with serious respiratory impairment. Hypoxemia is considered to be the most important challenge during OLV. The goal of this study was to establish the magnitude of intrapulmonary shunt, as well as the immensity of hypoxia during general anesthesia with OLV.Materials and Methods. In this prospective interventional clinical study thirty patients were enrolled who underwent elective thoracic surgery with a prolonged period of OLV. The patients received balanced general anesthesia with fentanyl/propofol/rocuronium. A double-lumen endobron-chial tube was inserted in all patients, and mechanical ventilation with 50% oxygen in air was used during the entire study. Arte-rial blood gases were recorded in a lateral decubitus position with two-lung ventila-tion, at the beginning of OLV (OLV 0) and at 10 and 30 min. (OLV 10, OLV 30, respectively) after initiating OLV in all patients. Standard monitoring procedures were used. Arterial oxygenation (PaO2), arterial oxygen saturation (SaO2) and ve-nous admixture percentage - intrapulmo-nary shunt (Qs/Qt %) were measured, as well as mean arterial pressure and heart rate during the same time intervals. For the purpose of this study, the quantitative value of Qs/Qt% was mathematically cal-culated using the blood gas analyser AVL Compact 3. A p value <0.05 was taken to be statistically significant.Results. When OLV was instituted, arterial oxygenation decreased, whereas Qs/Qt% increased, about 10 min. after commence-ment, with improvement of oxygenation approximately half an hour afterwards. A statistically relevant difference (p<0.05) occurred in PaO2, SaO2 and Qs/Qt at the different time points.Conclusion. Hypoxia during OLV, with an increase in Qs/Qt, usually occurs after 10 min. of its initiation. After 30 min, the val-ues of the Qs/Qt ratio regularly return to normal levels.

Investigation of one-lung ventilation postoperative cognitive dysfunction and regional cerebral oxygen saturation relations.

To explore the relationship of postoperative cognitive dysfunction (POCD) in one-lung ventilation (OLV) patients and regional cerebral oxygen saturation (rSO2). Twenty-nine male and twenty-one female cases of OLV received thoracic surgery, with American Standards Association (ASA) physical status being at Grades I-III. Neuropsychological tests were performed on the day before operation and 7 d after operation, and there was an intraoperative continuous monitoring of rSO2. The values of rSO2 before anesthesia induction (t1), at the beginning of OLV (t2), and at the time of OLV 30 min (t3), OLV 60 min (t4), the end of OLV (t5), and the end of surgery (t6) were recorded. The intraoperative average of rSO2 , the intraoperative minimum value of rSO2 (rSO(2, min)), and the reduced maximum percentage of rSO2 (rSO(2, %max)) when compared with the baseline value were calculated. The volume of blood loss, urine output, and the amount of fluid infusion was recorded. A total of 14 patients (28%) in the 50 cases suffered from POCD. The values of mini-mental state examination (MMSE), the digit span and the digit symbol on the 7th day after the operation for POCD in OLV patients were found to be significantly lower than those before the operation (P<0.05). The values of MMSE and vocabulary fluency scores were significantly lower than those in the non-POCD group (P<0.05). The values of rSO2 in the POCD group of OLV patients at t2 and t3 and the values of rSO2 in the non-POCD group at t2 were found to be significantly higher than those at t1 (P<0.05). The values of rSO(2, %max) in the POCD group were significantly higher than those in the non-POCD group (P<0.05). When the value of rSO(2, %max) is more than 10.1%, it may act as an early warning index for cognitive function changes. POCD after OLV may be associated with a decline in rSO2.

Effects of propofol versus sevoflurane combined with remifentanil anesthesia on activity of nuclear factor kappa B in neutrophil granulocyte during one-lung ventilation in patients undergoing radical resection of esophagus cancer

Objective To compare the effects of propofol versus sevoflurane combined with remifentanil anesthesia on the activity of nuclear factor-kappa B (NF-κB) in neutrophil granulocyte during one-lung ventilation (OLV) in patients undergoing radical resection of esophagus cancer.Methods Forty ASA physical status Ⅰ or Ⅱpatients of both sexes,aged 40-64 yr,with body mass index 18-25 kg/m2,undergoing radical resection of esophagus cancer,were randomized into 2 groups (n =20 each):propofol-remifentanil group (group P) and sevofluraneremifentanil group (group S).Anesthesia was induced with midazolam,sufentanil,etomidate and cisatracurium besylate in both groups.The patients were tracheal intubated and mechanically ventilated.Anesthesia was maintained with iv infusion of propofol 4-8 mg· kg-1 · min-1 in group P,or with inhalation of 1%-3% sevoflurane in group S,and with iv infusion of remifentanil 0.2μg· kg-1 · min-1 and intermittent iv boluses of cisatracurium besylate 7 mg in both groups.The Narcotrend index value was maintained between 40 and 50.Blood samples were taken from the radial artery at 5 min after intubation,the beginning of OLV,30,60 and 90 min of OLV,0 and 10 min after re-expansion of the collapsed lung,and the end of surgery for blood gas analysis and for determination of plasma concentrations of IL-1.The oxygenation index and respiratory index were calculated.The nuclear protein of neutrophil granulocytes was extracted for detection of NF-κB-DNA binding activity.Results Compared with group P,the respiratory index,plasma concentrations of IL-1 and NF-κB-DNA binding activity were significantly increased (P ＜ 0.05),and no significant change was found in the oxygenation index in group S (P ＞ 0.05).Conclusion Compared with sevoflurane-remifentanil anesthesia,propofol-remifentanil anesthesia can inhibit activation of NF-κB in neutrophil granulocyte and is helpful in attenuating the inflammatory response in lung tissues during OLV in patients undergoing radical resection of esophagus cancer. Key words: Propofol ; Anesthetics, inhalation ; Piperidines ; Respiration, artificial; NF-kappa B ; Neutrophils

Efficiency of the newly introduced ventilatory mode “pressure controlled ventilation-volume guaranteed” in thoracic surgery with one lung ventilation

BackgroundAnesthesia for thoracic surgery routinely involves one lung ventilation (OLV). Volume controlled ventilation (VCV) was and still the most common method of performing OLV. We assumed that pressure controlled ventilation-volume guaranteed (PCV-VG) is a better ventilation strategy for OLV than VCV as regard the inspiratory pressures, oxygenation parameters and post-operative ventilatory outcome.MethodsForty patients undergoing elective thoracic surgery in the lateral position requiring at least 1 h of OLV were randomly assigned into two groups. Group VCV: VCV was performed throughout the operation. Group PCV-VG: PCV-VG was performed throughout the operation. Blood gas analysis, peak inspiratory pressure (Ppeak), mean inspiratory pressure (Pmean), plateau inspiratory pressure (Pplateau) were measured: (1) During two lung ventilation (TLV1) 30 min after turning the patient to the lateral decubitus prior the beginning of OLV; (2) 30 min after initiation of OLV(OLV); (3) End of surgery: 30 min after reestablishing TLV (TLV2).ResultsThe Ppeak and the Pplateau were significantly lower in PCV-VG compared with VCV in all stages of the study (P value < 0.05). There was significant increase in all pressure values in OLV compared with TLV1 in the two groups (P value < 0.05). There were significant decrease in the mean Pao2 values during OLV and TLV2 compared with TLV1 in the two groups (P value < 0.05). Yet the Pao2 was significantly higher in the PCV-VG group at OLV and TLV2 compared to the OLV and TLV2 in VCV group. Also Pao2 was significantly lower in TLV2 compared with TLV1 in both groups (P value < 0.05).ConclusionIn patients undergoing thoracic surgery with OLV, pressure controlled volume guaranteed mode of ventilation decreases inspiratory pressure parameters and improve arterial oxygenation better than volume controlled ventilation.

Effect of cytokines and oxygenation during selective lobar blockade in thoracic surgery

Objective To determine the effect on concentrations of interleukin (IL-6) and tumor necrosis factor-α (TNF-α) in bronchoalveolar lavage fluid (BALF) and serum and oxygenation during selective lobar blockade. Methods Thirty patients undergoing esophagectomy or lobectomy were randomly assigned to the total lung collapse (TLC) group (n=15) and the selective lobar blockade (SLB) group( n=15). Anesthesia was induced and maintained with target-controlled infusion of propofol and remifentanil. After intubating with a 8.0 mm internal diameter single -lumen endotraeheal tube, by the guidance of fiberoptic bronchoscope, a 9F coopdech endobronchial blocker was placed into the target lobe in the SLB group, whereas the blocker was placed into the mainstem bronchus in the TLC group. Intermittent arterial blood gas analysis was performed at the following times: 15 min after two lung ventilation in the lateral decubitus position(T1)); 30 min (T2)and 60 min (T3) after TLC or SLB respectively; 15 min after recovering to two lung ventilation (T4), peak inspiratory airway pressure (Ppeak) was also recorded. BALF and blood samples were collected at T, and T4, the concentrations of IL-6 and TNF -α were measured using enzyme -linked immunosorbent assay. Results airway pressure increased significantly after the beginning of one-lung ventilation (F=215.746,P<0.05)in both groups, with more increasing extent in group T (F=53.798, P<0.01).Significant trends were found toward a better improvement in oxygention index with the group S compared with the group T after the beginning of one lung ventilation (F=1 3.747, P<0.05). IL-6 and TNF-αconcentrations of the serum and BALF collected at T4 increased significantly in both groups, but the concentrations of IL-6 and TNF-α in serum and BALF in the group S was lower than those in the TLC group (IL-6:F=1503.734,P<0.01;TNF-α:F=1423.486,P<0.05). The incidence of postoperative complications was comparable between both groups. Conclusion The SLB strategy improves oxygenation and decreases the proinflammatory cytokines during thoracic surgery. Key words: Thoracic surgery; Selective lobar blockade; Cytokines; Oxygenation

Re-expansion of the collapsed lung with room air mitigates oxidative stress injury following one-lung ventilation during esophageal cancer resection

Objective To determine whether re-expansion of the collapsed lung with room air can attenuate oxidative stress injury following one-lung ventilation during esophageal cancer resection. Methods Twenty-four ASA Ⅰ or Ⅱ patients aged 40-60 yr weighing 44-65 kg undergoing esophageal cancer resection were randomly divided into 2 groups (n=12 each) : room air group and pure oxygen group. Anesthesia was induced with midazolam, fentanyl, etomidate and atracurium and maintained with propofol and atracurium infusion and intermittent iv boluses of fentanyl. Right or left side double-lumen catheter (Fr 35, 37, 39) was inserted in each patient. Correct placement was verified by fiber-optic bronchoscopy. The patients were mechanically ventilated ( V_T 7-10 ml/kg, RR 12-16 bpm, FiO_2 1.0 during one-lung ventilation). P_(ET)CO_2 was maintained at 35-45 mm Hg. SpO_2 was maintained at 95%-100% during one-lung ventilation. Blood samples were collected at the beginning of one-lung ventilation (T_1 ), immediately before re-expansion of the collapsed lung (T_2) and 30 rain after re-expansion of the collapsed lung (T_3) for determination of serum levels of MDA, SOD and plasma level of protein carbonyl. Arterial blood samples were obtained at 2 h after operation for blood gas analysis. Results The plasma protein carbonyl level and serum MDA level were significantly increased while the serum SOD level was significantly decreased at T_3 as compared with thost at T_1 and T_2 in pure oxygen group. No significant change in serum levels of MDA, SOD and plasma level of protein carbonyl occurred during operation in room air group. The oxygenation index was significantly higher at 2 h after operation in room air group than in pure oxygen group. Conclusion Re-expansion of the collapsed lung with room air can attenuate the oxidative stress injury following one-lung ventilation during esophageal cancer resection. Key words: Air; Oxidative stress; Lung; Respiration, artificial; Esophageal neoplasms

The Effects of Intravenous Hyperoxygenated Solution Infusion on Systemic Oxygenation and Intrapulmonary Shunt During One-Lung Ventilation in Pigs

Many anesthetic methods have been applied to maintain acceptable oxygenation during one-lung ventilation (OLV). However, the optimal management has not been definitely determined. The aim of this study was to investigate whether intravenous hyperoxygenated solution (HOS) infusion would improve systemic oxygenation and reduce intrapulmonary shunt during OLV. Sixteen pigs (25-35 kg) were anesthetized, tracheally intubated, and mechanically ventilated. After placement of femoral artery and pulmonary artery catheters, a left-sided double-lumen tube (DLT) was placed via tracheotomy. The animals were allocated randomly to one of the two study groups (n = 8 each); control group (C group) and hyperoxygenated solution group (H group). Animals in H group received intravenous HOS infusion immediately after the beginning of OLV via internal right jugular vein with an infusion pump, and the rate of infusion was 15 mL.kg(-l).h(-l); and in C group, the same amount of lactate Ringer's solution (LRS) was used in place of HOS. Arterial and venous blood gases analysis were recorded in three phases: during two-lung ventilation just before beginning OLV (TLV), 30 min after beginning OLV (OLV + 30), and 60 min after beginning OLV (OLV + 60). We measured arterial oxygen saturation (SaO(2)), mixing venous oxygen saturation (S(V)O(2)), partial pressure of arterial oxygen (PaO(2)), partial pressure of mixing venous oxygen (PvO(2),) oxygen contents in systemic arterial and mixed venous blood (CaO(2), CvO(2)), and venous admixture percentage (Qs/Qt%). Heart rate (HR), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), and cardiac output (CO) were also recorded. After 30 and 60 min OLV, there was a significant decrease in PaO(2), SaO(2), PvO(2), SvO(2), CaO(2), and CvO(2), and a significant increase of Qs/Qt% in both groups (P < 0.01). The values of PaO(2), SaO(2), PvO(2), SvO(2), and CvO(2) in H group at both OLV + 30 and OLV + 60 were significantly higher than those in C group (P < 0.05, P < 0.01). Although the values of CaO(2) in H group were higher than those in C group at OLV + 30 and OLV + 60, there were no significant differences. Comparing the values of Qs/Qt% between the two groups at OLV + 30 and OLV + 60, there were also no significant differences. Intravenous HOS infusion led to minimal changes in intrapulmonary shunt, nevertheless, it could ameliorate arterial oxygenation obviously during OLV. This might be a new strategy to improve systemic oxygenation during OLV.