单肺通气期间不同吸入氧浓度对术中呼吸功能的影响

目的 探讨单肺通气（OLV）期间不同吸入氧浓度（FiO₂）对胸外科手术患者呼吸功能的影响。
方法 选择2020年11月至2021年8月择期行肺叶切除术的患者57例,男40例,女17例,年龄18～64岁,BMI 18～28 kg/m²,ASA Ⅰ或Ⅱ级。将患者随机分为三组：FiO₂ 45%组（L组）、FiO₂ 65%组（M组）和FiO₂85%组（H组）,每组19例。三组分别在OLV期间予以对应的FiO₂。记录术前肺通气功能检查指标,包括用力肺活量（FVC）、第1秒用力呼气量（FEV1）、1秒率（FEV1/FVC）、分钟最大通气量占预计值百分比（MVV%）。于OLV前5 min、OLV后10、20、30、60 min分别经桡动脉与右颈内静脉抽取动静脉血行血气分析,记录SaO₂、PaO₂、PaCO₂、Hb、Lac,并计算氧合指数（PaO₂/FiO₂）、肺内分流率（Qs/Qt）、死腔率（VD/VT）,记录以上各时点肺动态顺应性（Cdyn）、气道峰压（Ppeak）、HR和MAP。
结果 三组术前FVC、FEV1、FEV1/FVC、MVV%差异无统计学意义。OLV后10、20、30 min M组和H组PaO₂明显高于L组（P＜0.05）。OLV后10、20、30、60 min M组和H组PaO₂/FiO₂、Cdyn明显低于L组（P＜0.05）;H组PaO₂/FiO₂、Cdyn明显低于M组（P＜0.05）,Qs/Qt、Ppeak明显高于L组和M组（P＜0.05）。OLV后60 min M组Qs/Qt明显高于L组（P＜0.05）,H组PaO₂明显高于L组（P＜0.05）。OLV前5 min、OLV后10、20、30、60 min三组SaO₂、PaCO₂、Hb、Lac、HR、MAP差异无统计学意义。
结论 OLV期间使用FiO₂ 45%和FiO₂ 65%均可以减少肺内分流,提高肺顺应性,改善氧合。     

Placebo-controlled study of inhaled nitric oxide to treat hypoxaemia during one-lung ventilation

The aim of this prospective, placebo-controlled study was to assess if unilaterally inhaled nitric oxide 20 ppm could treat hypoxaemia during one-lung ventilation. Sixty patients undergoing pulmonary resection using a lateral thoracotomy were allocated randomly to a control or nitric oxide group (NO group). During one-lung ventilation in the lateral decubitus position, the lungs were ventilated mechanically with 90% oxygen--10% nitrogen. After randomization, if PaO2 decreased to less than 9.3 kPa during one-lung ventilation, nitric oxide 20 ppm or nitrogen was added to the inspired gas. The criterion for treatment efficacy was an increase in PaO2 to greater than 9.3 kPa after gas administration. Eight patients in the control group and eight in group NO experienced hypoxaemia during one-lung ventilation. PaO2 was not significantly different in the two groups at the time of gas administration (control group mean 8.0 (SD 0.6) kPa; NO group 8.5 (0.5) kPa). The efficacy criterion was reached in two of eight patients in the control and NO groups. The results of this study showed that inhaled nitric oxide 20 ppm, administered in the dependent lung, was not superior to nitrogen in the treatment of hypoxaemia during one-lung ventilation. Nitric oxide should not be recommended as an alternative to conventional management of hypoxaemia in this condition.      

Small-dose nitric oxide improves oxygenation during one-lung ventilation: an experimental study

Inhaled nitric oxide (NO) at 20 or 40 ppm does not improve arterial oxygenation during one-lung ventilation (OLV). The authors hypothesized that NO at smaller concentrations might improve oxygenation. Twelve piglets weighing 26 to 32 kg were studied. When PaO(2) had reached a plateau during OLV, NO at doses of 4, 8, 16, and 32 ppm were randomly administered for 30 min. Hemodynamic data were determined by invasive monitoring. Blood gas analysis and, in six animals, ventilation-perfusion analysis by the multiple inert gas elimination technique were used to characterize pulmonary gas exchange. NO at 4, 8, 16, and 32 ppm improved PaO(2) during OLV. NO at 4 ppm had a more intense effect on arterial oxygenation than doses of 8, 16, and 32 ppm (DeltaPaO(2), 42 +/- 35 mm Hg versus 22 +/- 20 mm Hg, 13 +/- 18 mm Hg, and 15 +/- 16 mm Hg; P < 0.05). NO at 4 ppm reduced intrapulmonary shunt flow, whereas a larger concentration exhibited no statistically significant effect. The authors conclude that NO improves arterial oxygenation more effectively at smaller doses than at larger doses. This dose-dependent effect remains to be confirmed in acute hypoxemia during OLV. IMPLICATIONS: Inhaled nitric oxide at 4 ppm improves arterial oxygenation during one-lung ventilation to a greater extent than larger doses, and this effect is caused by a reduction in intrapulmonary shunt.     

Modulation of lung reperfusion injury by nitric oxide: impact of inspired oxygen fraction

BACKGROUND: Attempts to attenuate lung reperfusion injury by administration of inhaled nitric oxide have yielded conflicting results. We hypothesized that the inspired oxygen fraction may play an important role in determining the outcome of nitric oxide therapy. METHODS: Rat lungs were reperfused in a circuit incorporating a support animal either immediately after flushing (group A) or after 24-hr hypothermic storage (groups B-D). During the first 10 min of reperfusion, grafts were ventilated with 95% oxygen in groups A and B, 95% oxygen and 20 ppm nitric oxide in group C, and 20% oxygen and 20 ppm nitric oxide in group D. Ventilation during the subsequent 50 min of reperfusion was with 100% oxygen only, in all groups. RESULTS: Graft function in group B was poor compared to group A in terms of blood flow and pulmonary artery and peak airway pressures. In group C, although 5 out of 10 grafts functioned at control levels, the remainder performed poorly. Function in group D, on the other hand, was uniformly good. CONCLUSIONS: Inhaled nitric oxide can prevent lung reperfusion injury, but this effect may be compromised by concurrent ventilation with high oxygen concentrations.     

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.     

异丙酚和安氟醚对单肺通气肺内分流及血浆一氧化氮和内皮素的影响

目的观察异丙酚和安氟醚对单肺通气(OLV)肺内分流的影响,及其肺动、静脉血浆一氧化氮(NO)和内皮素(ET)的变化。方法择期开胸OLV病人30例,随机均分为两组,安氟醚组吸入浓度1．8％,而异丙酚组微泵输入剂量6mg·kg-1·h-1。监测双肺通气(TLV)30min、OLV30、60min时的桡、肺动脉血气及肺动、静脉血浆NO和ET浓度。结果OLV后,两组病人不同时点肺内分流值(Qs／Qt)均比TLV时显著增加(P<0．01),其中安氟醚组较异丙酚组增加更为明显(P<0．05)。两组肺动、静脉血NO浓度在TLV、OLV期间变化不显著(P>0．05)。异丙酚组OLV后肺静脉血ET浓度比TLV时上升(P<0．01),而安氟醚组其变化不明显(P>0．05)。结论临床剂量异丙酚对缺氧性肺血管收缩无明显抑制作用。OLV肺泡缺氧可引起肺内皮细胞分泌ET或肺组织对ET清除作用减弱,安氟醚对其有抑制作用。     

The effects on increasing cardiac output with adrenaline or isoprenaline on arterial haemoglobin oxygen saturation and shunt during one-lung ventilation

Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO2) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO2.     

The effects on arterial haemoglobin oxygen saturation and on shunt of increasing cardiac output with dopamine or dobutamine during one-lung ventilation

Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial saturation should improve as the venous oxygen extraction per ml of blood decreases if the total oxygen consumption remains constant. Previous work demonstrated that this was not achieved with adrenaline or isoprenaline as increased shunting negated any benefit from improved cardiac output and mixed venous oxygen content. However pharmacological stimulation of cardiac output and venous oxygen without any increase in shunt should achieve the goal of improved arterial oxygenation. To test this hypothesis, seven pigs were subjected to one-lung ventilation and infused on separate occasions, with dopamine and with dobutamine in random order to increase the cardiac output. The mixed venous oxygen content, shunt fraction, oxygen consumption and arterial oxygen saturation were measured. With both dopamine and dobutamine there was a consistent rise in venous oxygen content. However, with dopamine, the mean shunt rose from 28% to 42% and with dobutamine, the mean shunt rose from 45% to 59% (both changes P<0.01). With dopamine, the mean arterial oxygen saturation fell by 4.7%, and with dobutamine by 2.9%, but neither fall was statistically significant. It is concluded that any benefit to arterial saturation which might occur from a dopamine- or dobutamine-induced increase in mixed venous oxygen content during one-lung ventilation is offset by increased shunting. During one-lung anaesthesia, there would appear to be no benefit to arterial saturation in increasing cardiac output with an infusion of either dopamine or dobutamine.     

Combined effects of inhaled nitric oxide and positive end-expiratory pressure during mechanical ventilation in acute respiratory distress syndrome

We studied the combined effects of inhaled nitric oxide (INO) and positive end expiratory pressure (PEEP) during mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Eleven patients received 0 and 4 parts per million of INO in random order for 30 min at PEEP levels of 0, 5, and 10 cm H2O. Respiratory and cardiovascular parameters were measured. The addition of INO and PEEP significantly improved arterial oxygenation (p < 0.005 and p < 0.0001, respectively). The combined effect of INO and PEEP on arterial oxygenation was remarkable during 10 cm H2O PEEP. There was synergistic effect on arterial oxygenation by combining INO and 10 cm H2O PEEP. The present study showed that the combination of INO and 10 cm H2O PEEP enhanced arterial oxygenation in patients with ARDS.     

单肺通气时吸入不同浓度氧对围术期氧合的影响

目的探讨食管癌患者术中单肺通气(OLV)时吸入不同浓度氧(FiO2)对围术期氧合的影响。方法选择拟行左侧剖胸食管癌根治术患者90例,随机均分为三组,每组30例,分别在OLV时将FiO2设定为60%(L组)、75%(M组)和90%(C组)。分别在麻醉前(T0)、OLV前(T1)、OLV 30min(T2)、60min(T3)、120min(T4)及恢复双肺通气(TLV)后30min(T5)、术后24h(T6)抽取动脉血测PaO2、SaO2、pH、PaCO2,计算氧合指数(PaO2/FiO2),同时持续监测SpO2、PETCO2、气道峰压(Ppeak)、气道平台压(Pplat)和气道顺应性(Cldyn)。结果 L组、M组、C组分别有6例、1例、1例患者在OLV 1h内SpO2下降到95%以下,被剔除出组。T2~T4时L组PaO2明显低于M、C组,M组明显低于C组(P0.05);T2~T4时L组SaO2、SpO2明显低于M、C组(P0.05)。三组各时点PaO2/FiO2、pH、PaCO2、PETCO2差异无统计学意义。结论左侧剖胸行食管癌根治术患者术中OLV时FiO2降低到75%时循环稳定,氧合充分。     

Low- vs high-dose almitrine combined with nitric oxide to prevent hypoxia during open-chest one-lung ventilation

Background. Almitrine combined with inhaled nitric oxide (NO)can prevent hypoxia during one-lung ventilation (OLV). The optimaldose of almitrine that would provide therapeutic advantage withfew side-effects during open-chest OLV has not been established. Methods. Forty-two patients undergoing thoracotomy were randomlyallocated to three groups: placebo, almitrine 4 µg kg^–1min^–1 and inhaled NO 10 p.p.m. (ALM4+NO), and almitrine16 µg kg^–1 min^–1 and inhaled NO 10 p.p.m.(ALM16+NO). Gas exchange, haemodynamic and respiratory variablesand plasma concentrations of almitrine and lactate were monitored.Measurements were obtained with the patient awake (baseline),after induction of anaesthesia with two-lung ventilation (control2LV), 20 min after treatment (2LV+T), and then at 10, 20 and30 min of OLV (OLV10', OLV20' and OLV30') with 1. Results. In the placebo group, OLV impaired and increased pulmonary shunt [16 (SD 7) kPa and 42 (10)% respectively].These improved with ALM4+NO [26 (10) kPa and 31 (7)%; P<0.001].ALM16+NO further improved to 36 (13) kPa (P<0.0001) but gave no improvement in the shunt. Mean pulmonaryartery pressure was similar in the placebo and ALM4+NO groups[20 (4) vs 23 (5) mm Hg], whereas it was increased in the ALM16+NOgroup to 28 (8) mm Hg (P<0.01). Plasma concentrations ofalmitrine and lactate were unaltered by the treatments. Conclusions. Low-dose almitrine (4 µg kg^–1 min^–1)together with inhaled NO significantly improves oxygenationduring open-chest OLV, without modifying pulmonary haemodynamics.An increased dose of almitrine (16 µg kg^–1 min^–1)with inhaled NO further improves arterial oxygenation, but alsoincreases mean pulmonary artery pressure.     

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.     

Cerebral oxygen desaturation during one-lung ventilation: correlation with hemodynamic variables

Purpose

Cerebral desaturation occurs frequently in patients undergoing one-lung ventilation for thoracic surgery. The mechanism of this desaturation is unclear regarding its etiology. The objective of this study was to investigate whether or not decreases in cerebral oxygen saturation associated with one-lung ventilation were a consequence of decreased cardiac output.

Methods

A blinded observational study was conducted in 23 patients undergoing one-lung ventilation with thoracic surgery. Eighteen patients completed the study. Cerebral oxygen saturation was monitored using near-infrared spectroscopy (FORE-SIGHT^® monitor). Invasive blood pressure was monitored and hemodynamic variables were interrogated using the FloTrac^® system. Anesthesia was maintained with sevoflurane with a F _i O₂ of 1.0. Post-hoc analysis involved a comparison between baseline and integrated changes in cerebral saturation, heart rate, stroke index, cardiac index, and stroke volume variability.

Results

All patients showed cerebral desaturation from a baseline of two-lung ventilation in the lateral decubitus position following institution of one-lung ventilation. The cardiac index was stable at these times, but with one-lung ventilation, the heart rate decreased and the stroke index increased to maintain a stable product. The integral of heart rate × time was inversely correlated with the integral of cerebral desaturation × time (linear regression analysis; P = 0.02; (df) = 16)).

Conclusions

Cerebral oxygen desaturation was universal during one-lung ventilation in this study. There was no correlation between cerebral desaturation and cardiac output or other hemodynamic variables.     

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。     

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.     

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.