The effects of increasing concentrations of desflurane on systemic oxygenation during one-lung ventilation in pigs.

During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction reduces venous admixture and attenuates the decrease in arterial O2 tension by diverting blood from the nonventilated to the ventilated lung. In vitro, increasing concentrations of desflurane depresses hypoxic pulmonary vasoconstriction in a dose-dependent manner. Accordingly, we investigated the effects of increasing concentrations of desflurane on oxygenation during OLV in vivo. Thirteen pigs (25-30 kg) were anesthetized (induction: propofol 2-3 mg/kg IV; maintenance: N2O/O2 50%/50%, desflurane 3%, propofol 50 microg x kg(-1) min(-1), and vecuronium 0.2 mg x kg(-1) x h(-1) IV), orotracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a leftsided, 28F, double-lumen tube was placed via tracheotomy. After double-lumen tube placement, N2O and desflurane were discontinued, propofol was increased to 200 microg x kg(-1) x min(-1), and the fraction of inspired oxygen was adjusted at 0.8. Anesthesia was then continued in random order with desflurane 5%, 10%, or 15% end-tidal concentrations while propofol was discontinued. Whereas mixed venous PO2, mean arterial pressure, cardiac output, and shunt fraction decreased in a dose-dependent manner, PaO2 remained unchanged with increasing concentrations of desflurane during OLV. These findings indicate that, in vivo, increasing concentrations of desflurane do not necessarily worsen oxygenation during OLV. IMPLICATIONS: Oxygenation during one-lung ventilation depends on reflex vasoconstriction in the nonventilated lung. In vitro, desflurane inhibits this reflex dose-dependently. Our results indicate that, in vivo, this does not necessarily translate to dose-dependent decreases in oxygenation during one-lung ventilation.     

The effects of xenon or nitrous oxide supplementation on systemic oxygenation and pulmonary perfusion during one-lung ventilation in pigs

During experimental one-lung ventilation (OLV), the type of anesthesia may alter systemic hemodynamics, lung perfusion, and oxygenation. We studied whether xenon (Xe) or nitrous oxide (N(2)O) added to propofol anesthesia would affect oxygenation, lung perfusion, and systemic and pulmonary hemodynamics during OLV in a pig model. Nine pigs were anesthetized, tracheally intubated, and mechanically ventilated. After placement of arterial and pulmonary artery catheters, a left-sided double-lumen tube was placed via tracheotomy. IV anesthesia with propofol was supplemented in random order with N(2)O/O(2) 60:40 or Xe/O(2) 60:40 or N(2)/O(2) 60:40. All measurements were made after stabilization at each concentration. Differential lung perfusion was measured with colored microspheres. Oxygenation (Pao(2): 90 +/- 17, 95 +/- 20, and 94 +/- 20 mm Hg for N(2)/O(2), N(2)O/O(2), and Xe/O(2)) and left lung perfusion (16% +/- 5%, 14% +/- 6%, and 18.8% for N(2)/O(2), N(2)O/O(2), and Xe/O(2)) during OLV did not differ among the 3 groups. However, mean arterial blood pressure (78 +/- 25, 62 +/- 23, and 66 +/- 23 mm Hg for N(2)/O(2), N(2)O/O(2), and Xe/O(2)) and mixed venous saturation (55% +/- 12%, 48% +/- 12%, and 50% +/- 12% for N(2)/O(2), N(2)O/O(2), and Xe/O(2)) were reduced during N(2)O/O(2) as compared with the control group (N(2)/O(2)). Supplementation of IV anesthesia with Xe or N(2)O does not impair oxygenation nor alter lung perfusion during experimental OLV.     

A comparison of the effects of desflurane and isoflurane on arterial oxygenation during one-lung ventilation

In a randomised prospective cross-over study, we compared the effects of desflurane and isoflurane on arterial oxygenation, heart rate and mean arterial pressure during one-lung anaesthesia. Thirty patients scheduled for oesophagogastrectomy were randomly assigned to one of two groups. One group of 15 patients received desflurane to an end-tidal concentration of 6% in oxygen from induction until the end of 30 min of open chest one-lung ventilation in the lateral position. This was followed by isoflurane to an end-tidal concentration of 1.1% in oxygen for the next 30 min of one-lung ventilation. The other group of 15 patients received the two anaesthetic agents in the reverse order. We found no significant difference in arterial oxygenation, heart rate or mean arterial pressure between the two inhalational agents. In the subgroup of 10 patients with pulmonary artery catheters, we found no significant differences in mixed venous saturation, derived shunt or cardiac output. We conclude that during one-lung ventilation, the choice between desflurane and isoflurane does not significantly influence arterial oxygenation.     

Lung perfusion,shunt fraction,and oxygenation during one-lung ventilation in pigs: the effects of desflurane,isoflurane, and propofol

OBJECTIVE: To study how desflurane, isoflurane, and propofol affect pulmonary perfusion, shunt fraction, and systemic oxygenation during one-lung ventilation (OLV) in vivo. DESIGN: Prospective animal study with a crossover design. SETTING: Animal laboratory of a university hospital. PARTICIPANTS: Twelve female pigs. INTERVENTIONS: The pigs were anesthetized, tracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a left-sided, double-lumen tube (DLT) was placed via tracheotomy. After DLT placement, F(I)O(2) was adjusted at 0.8, and anesthesia was continued in random order with 1 minimal alveolar concentration of desflurane, 1 minimal alveolar concentration of isoflurane, or propofol. MEASUREMENTS AND MAIN RESULTS: Measurements of respiratory and hemodynamic parameters were made after stabilization at each anesthetic. During OLV, perfusion of the nonventilated lung and shunt fraction were comparable during all 3 anesthetics. PaO(2) was lower during desflurane and isoflurane anesthesia as compared with propofol anesthesia. Mixed venous PO(2) and cardiac output were lower with desflurane and isoflurane as compared with propofol. CONCLUSIONS: In a clinically relevant model of OLV cardiac output, PaO(2) and mixed venous PO(2) decreased during desflurane and isoflurane as compared with propofol, whereas perfusion of the nonventilated lung and shunt fraction remained comparable.     

Effects of isoflurane on oxygenation during one-lung ventilation in pulmonary emphysema patients

Background: Hypoxic pulmonary vasoconstriction has an important role in human one-lung ventilation (OLV) in the lateral decubitus position under general anesthesia. During OLV, inhalational anesthesia may inhibit hypoxic pulmonary vasoconstriction and the decrease in arterial oxygenation. We studied the effect of isoflurane administration on arterial oxygen tension in chronic obstructive pulmonary disease patients.
Methods: Ten patients who had thoracoscopic laser ablation of bullous emphysema were studied. Patients received 2% isoflurane in oxygen from induction until the first 20 min of OLV in the lateral decubitus position, then were switched to 1% isoflurane lasting 20 min and next were switched to 0.5% isoflurane lasting 20 min. After each 20-min inhalation, pulmonary and hemodynamic parameters were measured. The given concentrations for isoflurane were merely vapor meter concentrations.
Results: PaO₂/FIO₂, Qs/Qt respiratory rate peak inspiratory pressure and PaCO₂ showed no significant changes at each point of isoflurane. Expiratory tidal volume significantly decreased (P<0.05) with 0.5% isoflurane compared to that with 2% isoflurane. Cardiac output, mean arterial pressure, mean pulmonary arterial pressure, systemic vascular resistance and pulmonary vascular resistance showed no significant changes at each point of isoflurane.
Conclusions: In patients with pulmonary emphysema, arterial oxygenation is not affected by low isoflurane concentration during OLV in the lateral decubitus position.     

比较地氟醚与异丙酚在电视胸腔镜手术中对病人氧合的影响

目的比较地氟醚和异丙酚在电视胸腔镜手术单肺通气中对病人的氧合影响.方法择期行电视胸腔镜手术病人20例,ASAⅡ～Ⅲ级,随机分为地氟醚组(D组)和异丙酚组(P组),每组10例.麻醉诱导P组或D组分别用芬太尼4μg@kg-1、维库溴铵0.1mg@kg-1、琥珀胆碱100mg,异丙酚2mg@kg-1(P组)或2.5%硫喷妥钠5mg@kg-1(D组),以2～8mg@kg-1@h-1异丙酚(P组)或2%～4%地氟醚(D组)、芬太尼、维库溴铵维持麻醉.静脉诱导后经口腔插入Carlen双腔支气管导管.监测术中MAP及HR的变化,并分别于术前、TLV30min、OLV30min、OLV60min取桡动脉血做血气分析.结果两组病人均于单肺通气后PaO2虽明显下降(P＜0.05),但PaO2＞60mmHg,组间无显著性差异.D组术中MAP明显低于术前,而P组无显著性变化.结论地氟醚与异丙酚均可安全地应用于单肺通气手术的麻醉.     

Effects of desflurane and propofol on arterial oxygenation during one-lung ventilation in the pig

Background: Desflurane depresses hypoxic pulmonary vasoconstriction (HPV) in vitro. During one-lung ventilation (OLV), HPV may reduce venous admixture and ameliorate the decrease in arterial O₂ tension by diverting blood from the non-ventilated to the ventilated lung. Accordingly, this study compares the effects of desflurane with those of propofol on oxygenation during two-lung (TLV) and OLV in vivo. Methods: Ten pigs (25–30 kg) were premedicated (flunitrazepam 0.4 mg/kg im), anaesthetized (induction: propofol 2 mg/kg iv; maintenance: N₂O/O₂ 50%/50%, desflurane 3%, propofol 50 μg kg^?1 min^?1, and vecuronium 0.2 mg kg^?1 h^?1 iv), orally intubated and mechanically ventilated. Femoral arterial and thermodilution pulmonary artery catheters were placed, and the orotracheal tube was replaced by a left-sided 28-Ch double-lumen tube (DLT) via tracheotomy. After DLT placement, N₂O and propofol were discontinued, FiO₂ was increased to 0.85, and anaesthesia continued randomly with either desflurane (1 MAC) or propofol 200 μg kg^?1 min^?1. Using a cross-over design, in each animal the effects of a), changing from TLV to OLV (left lung) during both desflurane and propofol and b), the effects of changing between the two anaesthetics during OLV were studied. Results: When changing from TLV to OLV, PaO₂ decreased more (P<0.05) during desflurane (mean 75%) than during propofol (mean 60%). Changing between desflurane and propofol during OLV resulted in small but consistent (P<0.05) increases in PaO₂ (mean 15%) during propofol. Conclusion: Consistent with in vitro results on HPV, 1 MAC desflurane impaired in vivo oxygenation during OLV more than did propofol.     

比较地氟醚、丙泊酚在单肺通气时对肺内分流的影响

目的　探讨地氟醚与丙泊酚在单肺通气期间对肺内分流、动脉氧分压的影响。方法　30例胸科手术病人 ,随机分为地氟醚组 (D组 ,1MAC)和丙泊酚组 (P组 ,6mg·kg 1·h 1)行循环紧闭麻醉。在手术前分别于平卧位双肺通气 30min、平卧位单肺通气 30min、侧卧位单肺通气 30min ,采集动脉血和混合静脉血行血气分析 ,计算肺内分流率。结果　在单肺通气后 ,D组和P组肺内分流增加明显 (P <0 0 1)。但平卧位分别增加 14 1%和 13 3% (P >0 0 5 ) ,侧卧位分别增加 13 2 %和12 7% (P >0 0 5 ) ,两组间无显著性差异。D组和P组动脉氧分压明显下降 (P <0 0 1) ,且平卧位比侧卧位下降更为明显。结论　 1MAC地氟醚在循环紧闭麻醉单肺通气期间对肺内分流和动脉氧合无明显的抑制。     

The effects of remifentanil and thoracic epidural on oxygenation and pulmonary shunt fraction during one-lung ventilation

OBJECTIVE: To compare the effects of remifentanil and thoracic epidural analgesia on the hemodynamic changes and pulmonary shunt fraction during one-lung ventilation (OLV) for thoracotomy. DESIGN: Prospective, single crossover design. SETTING: Tertiary care hospital. PARTICIPANTS: Thirty-four patients undergoing OLV for thoracic surgery. INTERVENTIONS: During general anesthesia with 2-lung ventilation, one-lung ventilation with remifentanil infusion, and one-lung ventilation with thoracic epidural anesthesia (TEA), hemodynamic parameters and arterial and mixed venous blood gases were taken from the radial and pulmonary artery catheters. During these 3 study periods, cardiac index (CI) was measured using thermodilution technique while shunt fraction (Qs/Qt), alveolar arterial oxygen gradient (A-a O(2)), and systemic (SVRI) and pulmonary vascular resistances indices (PVRI) were calculated. A p value <0.05 was taken to be statistically significant. MEASUREMENTS AND MAIN RESULTS: When OLV was instituted, there was a significant decrease in mean arterial blood pressure. Arterial oxygenation decreased, whereas CI and Qs/Qt increased during OLV, but there was no significant difference between remifentanil infusion and thoracic epidural analgesia. CONCLUSIONS: Both remifentanil infusion and TEA are suitable for analgesia during thoracic surgery when OLV is used. There was no significant difference in PaO(2) and Qs/Qt during each administration.     

Effects of isoflurane on regional pulmonary blood flow during one-lung ventilation

Isoflurane has been reported to inhibit hypoxic pulmonary vasoconstriction.However, the effects of one-lung ventilation and isofluraneon regional pulmonary blood flow (Qr) have not been investigatedin detail. Therefore, using radionuclide labelled microsphereswe measured Qr in rabbits (n = 8) in the left lateral decubitusposition during two- and one-lung ventilation under i.v. baselineanaesthesia and during additional administration of 1.5% isoflurane.Macrohaemodynamic variables were recorded continuously. Isofluraneincreased non-dependent lung blood flow during two-lung ventilation.One-lung ventilation caused a homogeneous decrease in Qr throughoutthe hypoxic lung, irrespective of isoflurane administration(P < 0.001). However, isoflurane significantly augmentedQr of the hypoxic lung during one-lung ventilation (P < 0.05).During all phases, Qr of the upper lobe was higher comparedwith that in the lower lobe in isogravitational slices of bothlungs; a ventrodorsal perfusion gradient was found in the leftupper lobe. We conclude that 1 .5% isoflurane increased perfusionof the non-dependent lung, inhibited hypoxic pulmonary vasoconstriction-inducedredistribution of pulmonary blood flow and did not influenceisogravitational perfusion gradients.     

The effects of acute isovolemic hemodilution on oxygenation during one-lung ventilation

Data on the effects of isovolemic hemodilution (IH) on oxygenation during one-lung ventilation (OLV) are lacking. We studied 47 patients with hemoglobin >14 g/dL who were scheduled for lung surgery (17 with normal lung function [group NL], 17 with chronic obstructive pulmonary disease [COPD] [group COPD], and 13 with COPD as control for time/anesthesia effects [group CTRL]). Anesthesia was standardized. The tracheas were intubated with a double-lumen tube. Ventilatory settings and fraction of inspired oxygen remained constant. The study was performed with patients in the supine position before surgery. OLV was initiated for 15 min. Two-lung ventilation was reinstituted, and IH was performed (500 mL); an identical volume of hydroxyethyl starch was administered. Subsequently, OLV was again performed for 15 min. In group CTRL, the same sequences of OLV were performed without IH. At the end of each period of OLV, pulmonary mechanics and blood gases were recorded. Data were analyzed by analysis of variance (mean +/- sd). In group NL and group CTRL, the arterial oxygen partial pressure remained constant, whereas it decreased in group COPD from 119 +/- 21 mm Hg before IH to 86 +/- 16 mm Hg after IH (P <0.01). Mild IH impairs gas exchange during OLV in COPD patients, but not in patients with normal lung function.     

The effects of intravenous almitrine on oxygenation and hemodynamics during one-lung ventilation

One-lung ventilation (OLV) induces an increase in pulmonary shunt sometimes associated with a decrease in PaO2 despite ventilation with 100% oxygen. PaO2 improvement has been reported in one-lung ventilated animals receiving IV almitrine, a pulmonary vasoconstrictor. We evaluated the ability of almitrine to prevent a decrease in PaO2 during OLV. Patients without pulmonary hypertension undergoing OLV for lung surgery were randomly assigned to receive either placebo (Group P, n = 8) or almitrine infusion at a rate of 8 microg x kg(-1) x min(-1) (Group A, n = 8) from the start of OLV. Gasometric and hemodynamic values were recorded with the patient in the lateral decubitus position during two-lung ventilation and at 10-min intervals during OLV over a 30-min period (OLV-10, OLV-20, OLV-30). Compared with the values found during two-lung ventilation (434 +/- 22 mm Hg in Group P and 426 +/- 23 mm Hg in Group A), PaO2 decreased at OLV-10 (305 +/- 46 mm Hg), OLV-20 (203 +/- 20 mm Hg), and OLV-30 (178 +/- 18 mm Hg) in Group P (P < 0.05) and at OLV-20 (354 +/- 25 mm Hg) and OLV-30 (325 +/- 17 mm Hg) in Group A (P < 0.05). PaO2 values differed between the groups at OLV-20 and OLV-30 (P < 0.05). Pulmonary artery pressure and cardiac output did not change. In conclusion, 8 microg x kg(-1) x min(-1) IV almitrine prevents and limits the OLV-induced decrease in PaO2 without causing any hemodynamic modification. IMPLICATIONS: Eight microg x kg(-1) x min(-1) IV almitrine limits one-lung ventilation-induced decrease in PaO2 without causing any hemodynamic modification in patients without pulmonary hypertension.     

单肺通气期间雷米芬太尼和硬膜外镇痛对血液氧合及肺内分流的影响

目的比较单肺通气（OLV）期间雷米芬太尼和胸段硬膜外镇痛对血液氧合及肺内分流的影响.方法14例择期开胸食管癌根治术患者,ASA Ⅰ～Ⅱ级.于全麻双肺通气（TLV）、雷米芬太尼输注OLV 30 min和停雷米芬太尼胸段硬膜外镇痛OLV 30 min,分别进行动、静脉血气分析,并计算肺内分流率（Qs/Qt）.结果与TLV时比较,OLV时动脉血氧分压（PaO2）明显下降,Qs/Qt明显升高（P＜0.01）,混合静脉血氧分压（PvO2）、动脉血氧饱和度（SaO2）、动脉血氧含量（CaO2）均明显下降（P＜0.05）.但OLV时输注雷米芬太尼与硬膜外镇痛相比,PaO2、Qs/Qt、PvO2、SaO2、CaO2均无显著性差异.结论OLV期间输注雷米芬太尼和硬膜外镇痛对血液氧合和肺内分流无明显影响.     

Halothane and isoflurane only slightly impair arterial oxygenation during one-lung ventilation in patients undergoing thoracotomy

Controversy exists as to whether the halogenated inhalation (IH) anesthetics impair arterial oxygenation during one-lung ventilation (1-LV). Accordingly, the authors have answered this question in 12 consenting patients who required 1-LV to facilitate the performance of thoracic surgery, by comparing arterial oxygenation during a prolonged period of IH anesthesia with arterial oxygenation during a prolonged period of intravenous (IV) anesthesia during stable 1-LV conditions. The patients were equally divided into halothane and isoflurane groups. Each patient in each IH anesthetic group underwent the following experimental sequence: step 1, two-lung ventilation (2-LV), 1 MAC IH anesthesia; step 2, 1-LV, 1 MAC IH anesthesia; step 3, 1-LV, iv anesthesia; step 4, 2-LV, iv anesthesia. Stable 1-LV conditions were proven by serial arterial blood gas measurement. Conversion from 2-LV to 1-LV during IH anesthesia (step 1 to step 2) caused a very large and significant decrease in PaO2 (from 484 +/- 49 to 116 +/- 61, and from 442 +/- 58 to 232 +/- 97 mmHg in the halothane and isoflurane groups, respectively) and increase in shunt (from 14 +/- 4 to 44 +/- 9, and from 19 +/- 5 to 31 +/- 8% in the halothane and isoflurane groups, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of sevoflurane compared with those of isoflurane on arterial oxygenation and hemodynamics during one-lung ventilation

Purpose. This study was designed to compare the effects of sevoflurane and isoflurane on Pao₂ and hemodynamic variables during one-lung ventilation (OLV) in surgical patients. Methods. Twelve patients undergoing an esophageal procedure with thoracotomy for which a long period of OLV was required were studied using a randomized crossover design. Group 1 received 1.2% isoflurane from the induction of anesthesia until 30 min after starting OLV, and then received 1.7% sevoflurane during the remaining period. In group 2, the order of the anesthetics was reversed. All experimental procedures were performed in the left lateral decubitus position with the chest opened. Arterial and mixed venous blood gases and cardiac outputs were analyzed immediately before OLV, during OLV, and after resumption of two-lung ventilation (TLV). Results. OLV produced lower Pao₂ and higher venous admixture (Q _s/Q _t) values than TLV. However, there was no significant difference between sevoflurane and isoflurane in Pao₂ or Q _s/Q _t during OLV. Other hemodynamic variables except for Pvˉo₂ showed no significant differences between the anesthetics. Conclusion. The effects of sevoflurane on Pao₂ and the hemodynamic variables were similar to those of isoflurane during TLV and OLV in the lateral decubitus position. Received for publication on January 29, 1999; accepted on August 6, 1999     

Effects of thoracic epidural anaesthesia on pulmonary venous admixture and oxygenation during one-lung ventilation

BACKGROUND: In this clinical randomized study, the effects of four anaesthesia techniques during one-lung ventilation [total intravenous anesthesia (TIVA) with or without thoracic epidural anaesthesia (TEA) (G-TIVA-TEA and G-TIVA), isoflurane anaesthesia with or without TEA (G-ISO-TEA and G-ISO)] on pulmonary venous admixture (Qs/Qt) and oxygenation (OLV) were investigated. METHODS: In 100 patients (four groups, 25 patients in each) undergoing thoracotomy, a thoracic epidural catheter was inserted pre-operatively. In G-TIVA-TEA and G-ISO-TEA, bupivacaine 0.1% + 0.1 mg/ml morphine was administered intra-operatively (10 ml of first bolus + 7 ml/h infusion). Propofol infusion or isoflurane concentration was adjusted to keep a bispectral index (BIS) of between 40 and 50 in all groups. FiO(2) was 0.8 during OLV and 0.5 before and after OLV. Partial arterial and central venous oxygen pressures (PaO(2) and PvO(2)), arterial and venous oxygen saturations and Qs/Qt values were recorded before, during and after OLV. RESULTS: During OLV, PaO(2) was significantly higher and Qs/QT significantly lower in G-TIVA-TEA and G-TIVA compared with G-ISO-TEA and G-ISO (PaO2: 188 +/- 36; 201 +/- 39; 159 +/- 33; 173 +/- 42 mmHg, respectively; Qs/Qt: 31.2 +/- 7.4; 28.2 +/- 7; 36.7 +/- 7.1; 33.7 +/- 7.7%, respectively). No statistical changes were observed in patients with TEA compared with without TEA in any measurement. CONCLUSION: During OLV, TEA does not significantly affect the oxygenation and Qs/Qt and can be used safely regardless of whether TIVA or inhalation techniques are used.     

雾化吸入前列腺素E1对家猪单肺通气期间分流及氧合的影响

随着心胸外科的发展、各种微创手术的推广,单肺通气(OLV)得到了广泛的应用。但是OLV时流经无通气肺的血液没有得到氧合回到左心,会造成静脉血掺杂、动脉血氧分压(PaO2)降低。虽然低氧性肺血管收缩效应(HPV)可使非通气肺血流减少并转向通气肺,减少了肺内分流,但仍有约9%~27%的病人可发生显著低氧血症[1]。而且HPV使肺血管阻力(PVR)显著增高,右心后负荷增大,可引发心脏病、低血容量以及肺动脉高压患者心脏功能急剧恶化。因此,寻找既能降低分流改善氧合又能降低PVR、减小心脏负荷的方法对于OLV今后更广泛的应用具有重要意义。由于通…