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.     

Arterial oxygenation during one-lung ventilation: combined versus general anesthesia

The optimal anesthetic management of patients undergoing thoracotomy for pulmonary resection has not been definitely determined. We evaluated whether general i.v. anesthesia (propofol-fentanyl) provides superior PaO2 during one-lung ventilation (OLV) compared with thoracic epidural anesthesia (TEA) with supplemental local and general anesthetics. We studied 60 patients who had prolonged periods of OLV for elective thoracic surgery for lung cancer and who were prospectively randomized into two groups. In 30 patients (GA group), fentanyl/propofol/rocuronium anesthesia was used. Another 30 patients (TEA group) were anesthetized with propofol/rocuronium/epidural thoracic bupivacaine 0.5%. A double-lumen endotracheal tube was inserted, and mechanical ventilation with 100% oxygen was used during the entire study. Arterial and venous blood gases were recorded before surgery in a lateral position with two-lung ventilation, 15 and 30 min after OLV (OLV + 15 and OLV + 30, respectively) in all patients. We measured PaO2, venous central oxygen tension, arterial and central venous oxygen saturation, venous admixture percentage (Qs/Qt%), and arterial and central venous oxygen content. The mean values for PaO2 during OLV in the GA group after 15 min (175 mm Hg) and 30 min (182 mm Hg) were significantly (P < 0.05) higher compared with the TEA group (120 and 118 mm Hg, respectively). Furthermore, Qs/Qt% was significantly (P < 0.05) increased in the TEA group during OLV. There were no other significant differences. We conclude that using the TEA regimen is associated with a lower PaO2 and a larger intrapulmonary shunt during OLV than with total i.v. anesthesia alone. IMPLICATIONS: Sixty patients undergoing elective lung surgery during a prolonged period of intraoperative one-lung ventilation were studied and randomized to receive general i.v. anesthesia or general i.v. anesthesia combined with thoracic epidural anesthesia. The arterial oxygenation in the first group was better than that in the second group during one-lung ventilation.     

The effect of positive end-expiratory pressure and continuous positive airway pressure on the oxygenation and shunt fraction during one-lung ventilation with propofol anesthesia.

STUDY OBJECTIVE: To evaluate the effect of positive end-expiratory pressure (PEEP) and continuous positive airway pressure (CPAP) on the oxygenation and shunt fraction during one-lung ventilation (OLV). DESIGN: Prospective clinical study. SETTING: Inpatient thoracic surgery and anesthesia clinic at an University hospital. PATIENTS: 15 patients with esophageal cancer who were scheduled for radical surgery. INTERVENTIONS: Arterial oxygenation, shunt fraction, and hemodynamics were evaluated at 20 min after the start of operation, at 20 minutes after the initiation of OLV under zero end-expiratory pressure (ZEEP), 20 minutes after the application of 4 cm PEEP to the dependent lung, at 20 minutes after OLV under ZEEP, 20 minutes after the application of 4 cm CPAP to the nondependent lung, and again under ZEEP, and after the combined application of PEEP and CPAP to the dependent and nondependent lungs. MEASUREMENTS AND MAIN RESULTS: There were no significant changes in mean pulmonary artery pressure, mean arterial blood pressure, heart rate, mixed venous partial pressure of oxygen, or arterial and mixed venous saturation of oxygen (SVO(2)) during this study. Arterial partial pressure of oxygen (pO(2)) increased and shunt fraction values decreased significantly after the application of PEEP (pO(2); 197.8 +/- 32.9 mmHg, Qs/Qt; 22.9 +/- 5.6%), CPAP (pO(2); 212.6 +/- 15.9 mmHg, Qs/Qt; 22.8 +/- 5.9%), and combination of PEEP and CPAP (pO(2); 222.0 +/- 42.8 mmHg, Qs/Qt; 24.1 +/- 6.4%) compared with ZEEP (pO(2); 128.1 +/- 37.5 mmHg, Qs/Qt; 33.2 +/- 6.8% ). But there were no significant differences regarding oxygenation and shunt fraction during PEEP, CPAP, or the combination of PEEP and CPAP. CONCLUSIONS: The application of PEEP to the dependent lung, CPAP to the nondependent lung, and the combination of PEEP and CPAP, are useful for improving oxygenation and decreasing Qs/Qt.     

单肺通气前通气侧肺前列腺素E_1超声雾化对气体交换的影响

目的观察单肺通气(OLV)前右侧肺前列腺素E1(PGE1)超声雾化对OLV期间肺内分流率(Qs/Qt)及动脉氧合的影响。方法择期行左胸食管癌根治术患者60例,随机均分为两组:在OLV前对右侧肺雾化吸入PGE10.2μg/kg(P组)和等量生理盐水(C组)。记录雾化吸入前(T1)、OLV 10min(T2)、OLV 15 min(T3)、OLV 30 min(T4)、OLV 60 min(T5)和OLV 120 min(T6)时的氧合指数及血流动力学指标。结果两组患者PaO2在OLV开始后均呈直线下降,其中C组在T4时降至最低点;T2~T4时P组PaO2明显高于C组(P0.05),且PaO2的最低值延迟至T5时出现。T2~T4时P组Qs/Qt明显低于C组(P0.05)。两组不同时点血流动力学差异无统计学意义。结论 OLV前右侧肺雾化吸入0.2μg/kg PGE1能减少肺内分流,改善氧合。     

Effects of thoracic epidural meperidine on arterial oxygenation during one-lung ventilation in thoracic surgery

OBJECTIVE: To compare the effects that the use of general intravenous anesthesia (propofol-fentanyl) (GA) or general anesthesia combined with thoracic epidural anesthesia with meperidine (TEA-M) may have on arterial oxygenation during one-lung ventilation (OLV). DESIGN: Prospective. SETTING: Tertiary care hospital. PARTICIPANTS: Seventy-two patients undergoing OLV for thoracic surgery. INTERVENTIONS: Patients were prospectively randomized into two groups: GA (n = 37) fentanyl, propofol, rocuronium anesthesia was used; and group TEA-M (n = 35) were anesthetized with propofol, rocuronium and thoracic epidural meperidine (2 mg/kg in 10-12 mL) administered before anesthetic induction. A double-lumen endotracheal tube was inserted, and mechanical ventilation with 100% oxygen was used during study. Mean arterial pressure, heart rate and arterial and venous blood gases were recorded with the patients in the lateral decubitus position in three phases: during two-lung ventilation (TLV), 15 and 30 minutes after beginning OLV (OLV + 15 and OLV + 30 respectively). The authors measured arterial and venous central oxygen tension, arterial and venous central oxygen saturation, arterial and venous central oxygen content and venous admixture percentage (Qs/Qt%). MEASUREMENTS AND MAIN RESULTS: There were no statistical differences between the two groups for PaO(2) during OLV + 15 (GA = 165 mmHg, TEA-M = 153 mmHg) and OLV + 30 (GA = 176 mmHg, TEA-M = 158 mmHg); and with values for Qs/Qt%. CONCLUSIONS: It is concluded that GA combined with TEA-M (2 mg/kg) do not affect arterial oxygenation during OLV in thoracic surgery.     

硬膜外阻滞复合全麻对单肺通气期间气体交换的影响

目的 观察胸段硬膜外阻滞复合全麻对单肺通气期间气体交换的影响.方法 随机选择ASA Ⅰ～Ⅱ级择期开胸手术病人80例,将病人随机分为两组,全麻复合硬膜外麻醉组(A组)和全麻组(B组),每组40例.两组病人在开胸前双肺通气20 min(T1)时及开胸后单肺通气(OLV)30 min(T2)、60 min(T3)、120 min(T4)时,分别采动脉血及混合静脉血,观察病人动静脉血气情况并计算肺内分流率(Qs/Qt)值、肺泡-动脉血氧分压差(A-aDO2)和无效腔量/潮气量(Vd/Vt)值.结果 与T1相比,两组T2-4时Paw均升高(P<0.01),T2-4时Qs/Qt均增加(P<0.01),A-aDO2增加(P<0.01),PaO2降低(P<0.01),而Vd/Vt,血压、心率变化无统计学差异(P>0.05);与B组相比,A组T2-4时的Qs/Qt增加(P<0.01),A-aDO2增加(P<0.01),PaO2,降低(P<0.01),而Vd/Vt,血压、心率变化无统计学差异(P>0.05).结论 单肺通气期间硬膜外阻滞复合全麻对肺换气功能有影响,使Qs/Qt增加,PaO2下降,A-aDO2增大;对肺泡通气功能指标Vd/Vt影响甚微.     

Inhalation administration of nitric oxide during selective pulmonary ventilation decreases the intrapulmonary shunt]

OBJECTIVE: To assess the effects of inhaled nitric oxide (NO) on oxygenation and hemodynamics in patients undergoing lung resection surgery during one-lung ventilation (OPV). PATIENTS AND METHODS: Prospective study of 16 patients aged 62 +/- 10 years scheduled for chest surgery under combined general and epidural anesthesia. During ventilation of only one lung, NO was administered for 15 minutes. Arterial blood and mixed venous blood samples were taken for analysis of blood gases and the calculation of intrapulmonary shunt. Pulmonary and systemic hemodynamic variables were also recorded using a Swan-Ganz catheter at three times: baseline (ventilation of both lungs), OLV, and with OLV plus NO (OLV NO). RESULTS: The most relevant data consisted of a significant decrease in shunt after start of NO inhalation in comparison with the level during OLV (31.1 +/- 0.5% versus 36 +/- 0.6%; p < 0.05). Arterial oxygen pressure decreased significantly during OLV and increased after start of NO (118.9 +/- 53.6 versus 155.4 +/- 78.5 mmHg; p < 0.05). Mean pulmonary artery pressure, pulmonary and systemic vascular resistances, and cardiac index did not change with inhalation of NO. CONCLUSIONS: Inhalational administration of NO during OLV significantly improves arterial oxygenation and decreases intrapulmonary shunt during OLV, without causing hemodynamic or systemic effects.     

单肺通气期间麻醉期用药对肺内分流的影响

背景 低氧血症是单肺通气(one lung ventilation,OLV)期间最常见的并发症.缺氧性肺血管收缩(hypoxic pulmonary vasoconstriction,HPV)是肺血管对局部低氧分压的反射性收缩,可以减少肺内分流(pulmonary shunt fraction,Qs/Qt)、维持动脉血氧分压(partial pressure of arterial oxygen,PaO2)、防止低氧血症的发生.目的 探讨OLV期间麻醉期用药对Qs/Qt的影响,指导临床应用.内容 综述OLV期间麻醉期用药对机体HPV、Qs/Qt和PaO2的影响.趋向 OLV期间麻醉期用药可以对HPV产生抑制或增强作用,从而影响Qs/Qt和PaO2.临床上要避免使用抑制HPV作用、增加Qs/Qt的药物,防止患者出现低氧血症.     

急性等容血液稀释对犬单肺通气期间肺分流与氧合的影响

目的 观察犬单肺通气期间，不同程度急性等容血液稀释对肺分流和氧供、氧耗等的影响。方法 12只健康杂种犬，基础麻醉后插入双腔气管导管，股动、静脉置管。稳定30分钟（HD0）后，以血定安等速置换全血，分别达到轻度（HD1）、中度（HD2）、重度（HD3）和极重度（HD4）血液稀释四个阶段。每阶段均分为双肺通气（TLV）和单肺通气（ OLV），分别于各阶段TLV、OLV15分钟后测量分流（Qs/Qt)及氧供（DO2）、氧耗（VO2）等各指标变化。结果 随着HD程度的加深，平均动脉压、心输出量、肺血管阻力（PVR）、平均肺动脉压（MPAP）、氧分压、DO2等趋于降低，氧摄取率（EPO2）、血乳酸、Qs/Qt趋于增加，到HD3、HD4时已出现DO2－VO2依赖性降低及无氧酵解征象。与TLV时相比，OLV期间HD0、HD1及HD2组PVR、MPAP增高明显（P＜0．01）。而HD3、H4D4组变化不大（P＞0．05） ；OLV时QS／Qt增加更为明显，HD2、HD3及HD4组分别较基值增加74％、164％及177％（P＜0．01） 。结论 缺氧、ANHD均为影响Qs/Qt与氧合的重要因素，OLV时ANHD应以不低于中度为准。     

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.     

Pulmonary gas exchange effects by nitroglycerin,dopamine and dobutamine during one-lung ventilation in man

The effects of nitroglycerin, dopamine and dobutamine on pulmonary gas exchange were determined in 21 adult patients during two-lung and one-lung ventilation. Nitroglycerin, in I μg·kg^?1·min^?1, decreased cardiac index (CI) andPaO₂ during both two-and one-lung ventilation, and increased in Qs/Qt during one-lung ventilation. There were no significant changes in the measured variables during infusion of dopamine, 5 μg·kg^?1·min^?1. Dobutamine, 5μg·kg^?1·min^?1, increased Cl and PaO₂ did not change during two-lung ventilation. During one-lung ventilation, PaO₂ increased from (mean value ±SD) 168 ± 46 to 201 ± 52 mmHg (P < 0.01) with dobutamine infusion. Qs/Qt decreased from 29.2 ± 7.0 to 26.0 ± 6.2 per cent (P < 0.05) without any change in pulmonary vascular resistance index during one-lung ventilation. We conclude that dobutamine has advantages over dopamine and nitroglycerin during one-lung ventilation.     

Pressure-controlled versus volume-controlled ventilation during one-lung ventilation in the prone position for robot-assisted esophagectomy

Background

The prone position during robotic esophageal mobilization for minimally invasive esophagectomy (MIE) provides several advantages with regards to operative times, surgeon ergonomics, and surgical view; however, this technique requires one-lung ventilation (OLV). There are no guidelines about ventilatory modes during OLV in the prone position. We investigated the effects of volume-controlled (VCV) and pressure-controlled ventilation (PCV) on oxygenation and intrapulmonary shunt during OLV in the prone position in patients who underwent robot-assisted esophagectomy.

Methods

Eighteen patients, no major obstructive or restrictive pulmonary disease, were allocated randomly to one of two groups. In the first group (n = 9), OLV was started by VCV and the ventilator was switched to PCV after 30 minutes. In the second group (n = 9), the modes of ventilation were performed in the opposite order in the prone position. Hemodynamic and respiratory variables were obtained during OLV at the end of each ventilatory mode.

Results

There were no significant differences in arterial oxygen tension (PaO₂), airway pressures, dynamic lung compliance, or physiologic dead space (Vd/Vt) during OLV between PCV and VCV in the prone position. Intrapulmonary shunt (Qs/Qt) was significantly lower with VCV than with PCV during OLV in the prone position (p = 0.044).

Conclusion

PCV provides no advantages compared with VCV with regard to respiratory and hemodynamic variables during OLV in the prone position. Either ventilatory mode can be safely used for patients who undergo robot-assisted esophagectomy and who have normal body mass index and preserved pulmonary function.     

Thoracic epidural anesthesia combined with general anesthesia: the preferred anesthetic technique for thoracic surgery

Thoracic epidural anesthesia (TEA) combined with general anesthesia (GA) as well as total-IV anesthesia (TIVA) are both established anesthetic managements for thoracic surgery. We compared them with respect to hypoxic pulmonary vasoconstriction, shunt fraction and oxygenation during one-lung ventilation. Fifty patients, ASA physical status II-III undergoing pulmonary resection were randomly allocated to two groups. In the TIVA group, anesthesia was maintained with propofol and fentanyl. In the TEA group, anesthesia was maintained with TEA (bupivacaine 0.5%) combined with low-dose concentration 0.3-0.5 vol% of isoflurane (end-tidal). Changing from two-lung ventilation to one-lung ventilation caused a significant increase in cardiac output (CO) in the TIVA group, whereas no change was observed in the TEA group. One-lung ventilation caused significant increases in shunt fraction in both groups which was associated per definition with a significant decrease in PaO(2) in both groups but PaO(2) remained significantly increased in the TEA group (P < 0.05). We conclude that both anesthetic regimens are safe intraoperatively. However, TEA in combination with GA did not impair arterial oxygenation to the same extent as TIVA, which might be a result of the changes in CO. Therefore, patients with preexisting cardiopulmonary disease and impaired oxygenation before one-lung ventilation might benefit from TEA combined with GA. IMPLICATIONS: Fifty patients underwent lung surgery through the opened chest wall requiring ventilation of only one lung. Patients were randomly assigned to receive either general anesthesia alone or in combination with regional anesthesia via a catheter in the back. Oxygen content in the blood and blood pressure was better maintained in the group receiving the combination of general with regional anesthesia.     

Inhaled nitric oxide administration during one-lung ventilation in patients undergoing thoracic surgery

OBJECTIVE: To evaluate the effects of inhaled nitric oxide (iNO) on hemodynamics and oxygenation during one-lung ventilation (OLV) in the lateral decubitus position in patients undergoing elective thoracic surgery. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Thirty consecutive patients scheduled for thoracotomy. INTERVENTIONS: Anesthesia consisted of thoracic epidural analgesia combined with general anesthesia (isoflurane, fentanyl, and vecuronium bromide). Systemic and pulmonary circulations were monitored with a radial artery catheter and a pulmonary artery catheter. Inhaled NO, 40 ppm, was administered during OLV, and the inhaled gas mixture was monitored for NO and nitrogen dioxide (NO2). Hemodynamic and oxygenation data were collected before and during inhaled NO administration. MEASUREMENTS AND MAIN RESULTS: Inhaled NO caused a reduction of pulmonary vascular resistance index from 249 +/- 97.6 dyne. sec. cm(-5) to 199.3 +/- 68.9 dyne. sec. cm(-5) (p < 0.05), without effects on systemic hemodynamics or impairment of oxygenation. A stratification of the patients according to values of QS/QT (< 30%, 30% to 44%, > or = 45%), PaO(2)/fraction of inspired oxygen (> or = 200, 100 to 199, < 100), and pulmonary hypertension (mean pulmonary arterial pressure < 24 or > or = 24 mmHg) showed that inhaled NO causes a significant reduction of mean pulmonary artery pressure in patients with pulmonary hypertension, mainly as a result of a reduction of pulmonary vascular resistance index, and improves oxygenation by reducing intrapulmonary shunt in patients with severe hypoxemia during OLV. CONCLUSIONS: Inhaled NO administration neither significantly decreased mean pulmonary arterial pressure in patients with normal pulmonary artery pressure nor improved oxygenation in nonhypoxic patients. Nevertheless, inhaled NO is effective in patients with pulmonary hypertension and hypoxemia during OLV.     

Lung recruitment improves the efficiency of ventilation and gas exchange during one-lung ventilation anesthesia

Atelectasis in the dependent lung during one-lung ventilation (OLV) impairs arterial oxygenation and increases dead space. We studied the effect of an alveolar recruitment strategy (ARS) on gas exchange and lung efficiency during OLV by using the single-breath test of CO(2) (SBT-CO(2)). Twelve patients undergoing thoracic surgery were studied at three points in time: (a) during two-lung ventilation and (b) during OLV before and (c) after an ARS. The ARS was applied selectively to the dependent lung and consisted of an increase in peak inspiratory pressure up to 40 cm H(2)O combined with a peak end-expiratory pressure level of 20 cm H(2)O for 10 consecutive breaths. The ARS took approximately 3 min. Arterial blood gases, SBT-CO(2), and metabolic and hemodynamic variables were recorded at the end of each study period. Arterial oxygenation and dead space were better during two-lung ventilation compared with OLV. PaO(2) increased during OLV after lung recruitment (244 +/- 89 mm Hg) when compared with OLV without recruitment (144 +/- 73 mm Hg; P < 0.001). The SBT-CO(2) analysis showed a significant decrease in dead-space variables and an increase in the variables related to the efficiency of ventilation during OLV after an ARS when compared with OLV alone. In conclusion, ARS improves gas exchange and ventilation efficiency during OLV. IMPLICATIONS: In this article, we showed how a pulmonary ventilatory maneuver performed in the dependent lung during one-lung ventilation anesthesia improved arterial oxygenation and dead space.     

A noninvasive partial carbon dioxide rebreathing technique for measurement of pulmonary capillary blood flow is also a useful oxygenation monitor during one-lung ventilation

STUDY OBJECTIVES: To test the hypothesis that effective pulmonary capillary blood flow can be a useful indicator for estimating appropriate oxygenation and ventilation during one-lung ventilation in lung surgery. DESIGN: Prospective data analysis. SETTING: A 770-bed general teaching hospital. PATIENTS: 15 ASA physical status II and III patients undergoing elective lung surgery. INTERVENTIONS: Patients received general and thoracic epidural anesthesia and underwent lung operation with one-lung ventilation. MEASUREMENTS: We measured effective pulmonary capillary blood flow by a partial CO2 rebreathing method and oxygenation parameters during two-lung ventilation before surgery, during one-lung ventilation, and during two-lung ventilation after lung surgery. MAIN RESULTS: The effective pulmonary capillary blood flow index significantly decreased by 31.6%, which was associated with a significant decrease in arterial oxygen tension (PaO2). The pulmonary shunt fraction increased to 46.3% during one-lung ventilation. During two-lung ventilation, after chest closure, effective pulmonary capillary blood flow index divided by heart rate (i.e., effective pulmonary blood stroke flow index) was still significantly lower than that seen during two-lung ventilation before thoracotomy. There were significant correlations between effective pulmonary capillary blood flow, pulmonary blood stroke flow index, and PaO2. CONCLUSIONS: Effective pulmonary capillary blood flow index and effective pulmonary blood stroke flow index are useful indicators for determining appropriate oxygenation therapy during one-lung ventilation.     

One-lung anesthesia--a comparison of pulmonary gas exchange during anesthesia with ketamine or enflurane

Twenty-four men undergoing elective pulmonary resection with a period of one-lung ventilation were studied to compare the effects of ketamine-O2 and enflurane-O2 anesthesia on arterial oxygen tension (PaO2) and intrapulmonary shunting (Qs/Qt). No statistically significant differences were demonstrated between ketamine and enflurane in mean peak Qs/Qt, 43% and 42%, respectively, or minimum PaO2 values, 169 torr and 127 torr, respectively. Stroke volume index, left ventricular stroke work index, and cardiac index were, however, significantly greater with ketamine. No emergence hallucinations were observed in either group. These findings suggest that ketamine affords no advantage over enflurane anesthesia in terms of Qs/Qt, and arterial oxygen desaturation during endobronchial anesthesia.     

肺叶切除术患者不同通气模式下每搏量变异度的变化

目的 探讨肺叶切除术患者不同通气模式下每搏量变异度(SW)的变化.方法 择期行肺叶切除术患者44例,年龄44～64岁,体重47～86 kg,ASA分级Ⅰ或Ⅱ级.采用FloTrac压力换能器及Vigileo心输出量监测仪持续监测CI、每搏量指数(SVI)和SVV.术中补液速率6～8 ml·kg-1·h-1(晶胶比1∶1)维持血容量.于仰卧位双肺通气5 min(T1)、侧卧位双肺通气2 min(T2)、单肺通气开胸前(T3)、单肺通气开胸后5 min(T4)、30 min(T5)、单肺通气+PEEP5 cm H2O 1 min(T6)、15 min(T7)、肺复张前(T8)、肺复张即刻(T9)和肺复张后1 min(T10)时记录SVV、CI和SVI.SVV＜ 13％为正常值.结果 患者术中血液动力学平稳,CI和SⅥ均在正常范围内波动.T9时SVV＞13％,其余各时间点均＜13％.SVV T2,3之间差异无统计学意义,T5～7之间差异均无统计学意义(P＞0.05);T9时SVV较T8.10时升高(P＜0.01).结论 肺叶切除术中,单肺通气以及单肺通气联合PEEP 5 cm H2O时SVV可用于指导液体治疗的判断,而在肺复张时SVV不能指导液体治疗.     

帕瑞昔布钠对食管癌根治术患者单肺通气时肺内分流的影响

目的 探讨帕瑞昔布钠对食管癌根治术患者单肺通气(OLV)时肺内分流的影响.方法 择期行食道癌根治术患者45例,年龄47～57岁,体重42～59kg,ASA分级Ⅰ或Ⅱ级,随机分为2组:生理盐水组(C组,n=23)和帕瑞昔布钠组(P组,n=22).P组静脉注射帕瑞昔布钠40 mg(生理盐水稀释至10 ml),C组静脉注射等容量生理盐水.随后两组均靶控输注异丙酚(效应室靶浓度4μg/m1)和舒芬太尼(效应室靶浓度0.3 ng/ml)行麻醉诱导,静脉注射罗库溴铵0.9 mg/kg,光纤支气管镜引导下插入双腔气管导管,行机械通气.于麻醉诱导开始后30 min(T0)、单肺通气15 min(T1)、30 min(T2)、1 h(T3)、恢复双肺通气30 min(T4)和1 h(T5)时测定CVP、HR、MAP和气道平均压(Pmean),同时采集颈内静脉和桡动脉血样,进行血气分析,计算肺内分流率(Qs/Qt).结果 与T0时比较,两组T1-3时Pmean 和Qs/Qt升高(P＜0.05);与T1时比较,两组T2.3.时Qs/Qt降低(P＜0.05);两组各时点Pmean、Qs/Qt、CVP、HR和MAP比较差异无统计学意义(P＞0.05).结论 帕瑞昔布钠40 mg对食管癌根治术患者单肺通气时缺氧性肺血管收缩反应无影响.     

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

During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction (HPV) reduces venous admixture and attenuates the decrease in arterial oxygen tension by diverting blood from the nonventilated lung to the ventilated lung. In vitro, desflurane and isoflurane depress HPV in a dose-dependent manner. Accordingly, we studied the effects of increasing concentrations of desflurane and isoflurane on pulmonary perfusion, shunt fraction, and PaO(2) during OLV in vivo. Fourteen pigs (30-42 kg) 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, FIO(2) was adjusted at 0.8 and anesthesia was continued in random order with 3 concentrations (0.5, 1.0, and 1.5 minimal alveolar concentrations) of either desflurane or isoflurane. Differential lung perfusion was measured with colored microspheres. All measurements were made after stabilization at each concentration. Whereas mixed venous PO(2), mean arterial pressure, cardiac output, nonventilated lung perfusion, and shunt fraction decreased in a dose-dependent manner, PaO(2) remained unchanged with increasing concentrations of desflurane and isoflurane during OLV. In conclusion, increasing concentration of desflurane and isoflurane did not impair oxygenation during OLV in pigs. IMPLICATIONS: In an animal model of one-lung ventilation, increasing concentrations of desflurane and isoflurane dose-dependently decreased shunt fraction and perfusion of the nonventilated lung and did not impair oxygenation. The decreases in shunt fraction are likely the result of anesthetic-induced marked decreases in cardiac output and mixed venous saturation.