Objective: Lung injury induced by one-lung ventilation is rare, but it is acondition that may result in high mortality. This study evaluates the effects ofone-lung ventilation and occlusion time on collapsed and contralateral lungs.Methods: Sprague-Dawley rats were allocated randomly into 7 groups consisting of6 animals each: sham; O1, 1 hour of occlusion/2 hours of re-expansion; C1, 3 hoursof mechanical ventilation control; O2, 2 hours of occlusion/2 hours of re-expansion;C2, 4 hours of mechanical ventilation control; O3, 3 hours of occlusion/2 hours ofre-expansion; and C3, 5 hours of mechanical ventilation control groups. In theocclusion groups, the left lung was collapsed by bronchial occlusion. Malondialdehydeactivity was determined in the blood, and myeloperoxidase and malondialdehydeactivity was determined in the collapsed and contralateral lungs. Lung tissueswere also examined histopathologically.Results: Malondialdehyde and myeloperoxidase levels rose as occlusion durationincreased. This increase was greater in the occlusion groups than that in their owncontrol groups. Increases were significant in the O2 compared with the O1 groups(P .005). Histologically, tissue damage increased as occlusion time rose injury incollapsed and contralateral lungs. Injury was greater in the occlusion groups thaninjury in their own control groups (P .005).Conclusions: Our findings show that biochemical and histopathologic injury occurin collapsed and contralateral lungs in one-lung ventilation, and this injury increasesas occlusion time rises. We believe that occlusion and occlusion time-related injuryshould be borne in mind in the clinic under conditions requiring the application of one-lung ventilation.

Kuzkov, Vsevolod V. MD, PhD; Suborov, Evgeny V. MD; Kirov, Mikhail Y. MD, PhD; Kuklin, Vladimir N. MD, PhD; Sobhkhez, Mehrdad MSci; Johnsen, Solveig MD; Waerhaug, Kristine MD; Bjertnaes, Lars J. MD, PhD

Institution From the Department of Anesthesiology, Institute of Clinical Medicine, University of Tromso, Tromso, Norway (VVK, EVS, MYK, VNK, MS, SJ, KW, LJB); and the Department of Anesthesiology and Intensive Care Medicine, Northern State Medical University, Arkhangelsk, Russian Federation (VVK, EVS, MYK).

Abstract Objective: To compare the single thermodilution and the thermal-dye dilution techniques with postmortem gravimetry for assessment of changes in extravascular lung water after pneumonectomy and to explore the evolution of edema after injurious ventilation of the left lung.

Design: Experimental study.

Setting: University laboratory.

Subjects: A total of 30 sheep weighing 35.6 +/- 4.6 kg. The study included two parts: a pneumonectomy study (n = 18) and an injurious ventilation study (n = 12).

Methods: Sheep were anesthetized and mechanically ventilated with an Fio2 of 0.5, tidal volume of 6 mL/kg, and positive end-expiratory pressure of 2 cm H2O. In the pneumonectomy study, sheep were assigned to right-sided pneumonectomy (n = 7), left-sided pneumonectomy (n = 7), or lateral thoracotomy only (sham operation, n = 4). In the injurious ventilation study, right-sided pneumonectomy was followed by ventilation with a tidal volume of 12 mL/kg and positive end-expiratory pressure of 0 cm H2O (n = 6) or by ventilation with a tidal volume of 6 mL/kg and positive end-expiratory pressure of 2 cm H2O for 4 hrs (n = 6). Volumetric variables, including extravascular lung water index (EVLWI), were measured with single thermodilution (STD; EVLWISTD) and thermal-dye dilution (TDD; EVLWITDD) techniques. We monitored pulmonary hemodynamics and respiratory variables. After the sheep were killed, EVLWI was determined for each lung by gravimetry (EVLWIG).

Results: In total, the study yielded strong correlations of EVLWISTD and EVLWITDD with EVLWIG (n = 30; r = .83 and .94, respectively; p < .0001). After pneumonectomy, both the left- and the right-sided pneumonectomy groups displayed significant decreases in EVLWISTD and EVLWITDD. The injuriously ventilated sheep demonstrated significant increases in EVLWI that were detected by both techniques. The mean biases (+/-2 sd) compared with EVLWIG were 3.0 +/- 2.6 mL/kg for EVLWISTD and 0.4 +/- 1.6 mL/kg for EVLWITDD.

Conclusions: After pneumonectomy and injurious ventilation of the left lung, TDD and STD displayed changes in extravascular lung water with acceptable accuracy when compared with postmortem gravimetry. Ventilator-induced lung injury seems to be a crucial mechanism of pulmonary edema after pneumonectomy.

Ozcan PE. Senturk M. Sungur Ulke Z. Toker A. Dilege S. Ozden E. Camci E.
Institution
Department of Anaesthesiology, Istanbul Medical Faculty, Istanbul University, Capa 34093, Istanbul, Turkey.
Title
Effects of thoracic epidural anaesthesia on pulmonary venous admixture and oxygenation during one-lung ventilation.
Source
Acta Anaesthesiologica Scandinavica. 51(8):1117-22, 2007 Sep.

Abstract
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.

Unzueta, M Carmen MD, PhD; Casas, J Ignacio MD; Moral, M Victoria MD.
Anesth Analg. 2007 May;104(5):1029-33

From the Department of Anesthesiology, Hospital de Sant Pau, Barcelona, Spain.
Accepted for publication January 15, 2007.
Supported by Departmental resources.
Address correspondence to M. Carmen Unzueta, Sant Antonio Ma Claret 167, Barcelona 08025, Spain. Address e-mail to mcunzueta@telefonica.net.
Abstract
BACKGROUND: Pressure-controlled ventilation (PCV) has been suggested as a tool to improve oxygenation during one-lung ventilation (OLV) for patients undergoing thoracic surgery. In this study we investigated whether PCV results in improved arterial oxygenation compared with volume-controlled ventilation (VCV) during OLV.

METHODS: Fifty-eight patients with good preoperative pulmonary function scheduled for thoracic surgery were prospectively randomized into two groups. Those in group A underwent OLV initially with VCV for 30 min followed by PCV for a similar period of time. Those in group B underwent OLV initially with PCV for 30 min followed by VCV for a similar duration. Airway pressures and arterial blood gases were obtained during OLV at the end of each ventilatory mode.

RESULTS: There were no differences during OLV in arterial oxygenation between VCV (Pao2, 206.1 ± 62.4 mm Hg) and PCV (Pao2, 202.1 ± 56.4 mm Hg; P = 0.534). Peak airway pressure was lower with PCV than with VCV (24.43 ± 3.42 cm H2O vs. 34.16 ± 5.21 cm H2O; P < 0.001).

CONCLUSIONS: The use of PCV during OLV does not lead to improved oxygenation during OLV compared with VCV for patients with good preoperative pulmonary function, but PCV did lead to lower peak airway pressures. Further study is needed for patients with severe obstructive or restrictive pulmonary disease.

The majority of studies of Nitric Oxide (NO) during one-lung ventilation over the past five years have shown that NO does not cause a significant increase in the mean PaO2. One recent study(1) shows that among patients with hypoxemia (defined here as PaO2/FiO2 <100) there was an increase in mean arterial oxygenation with NO 40ppm. Examining the data shows that a small minority of hypoxemic patients (approximately 25%)will have a clinically useful increase in PaO2 with NO. Examining the data of previous studies(2) it can be seen in other studies that a few patients with borderline hypoxemia will have an increase in PaO2 with NO. Although this does not make NO a useful therapy for hypoxemia during one-lung ventilation it does raise the possibility that it may be possible to identify the minority of patients who respond to NO. Continue Reading »

Peter Slinger MD, FRCPC
Assoc. Professor, Dept. Anesthesia, University of Toronto

The incidence of hypoxemia during one-lung ventilation (OLV) with an inspired oxygen concentration (FiO2) of 1.0 has declined from levels of 20-25% in the 1970’s to less than 10% today. Two advances in thoracic anaesthesia affect oxygenation. First, the routine use of fiberoptic bronchoscopy to position DLTs. Second, improved anesthetic techniques with lower doses of volatile agents. Continue Reading »