Archive for 5:38 PM

Effect of thoracic epidural analgesia on gastric blood flow after oesophagectomy.Acta Anaesthesiologica Scandinavica. Volume 51 Issue 5 Page 587-594, May 2007

Background: The oesophagectomy procedure includes the formation of a gastric tube to re-establish the continuity of the gastrointestinal tract. The effect of thoracic epidural analgesia (TEA) on gastric mucosal blood flow (GMBF) remains unknown in clinical practice. The aim of this prospective observational study was to assess the microcirculatory changes induced by TEA in the early post-operative course.

Methods: Eighteen consecutive patients who underwent radical oesophagectomy with en-bloc resection and two-field lymphadenectomy for oesophageal cancer, and benefited from TEA during the post-operative course, were studied prospectively, and compared with nine patients who declined the use of TEA in the same period (control group). GMBF was measured using a laser Doppler flowmeter in three consecutive time periods (before and after 1 and 18 h of TEA infusion). Post-operative monitoring also included the measurement of arterial pressure, cardiac output, gas exchange and intrathoracic blood volume index.

Results: After the first and 18th hour of infusion, TEA induced an increase in GMBF compared with baseline and the control group. The mean arterial pressure and intrathoracic blood volume index decreased after the first hour of TEA infusion with no influence on the cardiac index.

Conclusions: This clinical study demonstrates that TEA improves the microcirculation of the gastric tube in the early post-oesophagectomy period. The clinical relevance of TEA in this setting should be validated in larger studies focusing on the clinical outcome following oesophagectomy.

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One-lung ventilation: For how long? Celal Tekinbas, MD, Hulya Ulusoy,Esin Yulug, et al. J Thorac Cardiovasc Surg 134: 405-10, 2007

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.

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Extravascular lung water after pneumonectomy and one-lung ventilation in sheep. Critical Care Medicine. 35(6):1550-1559, June 2007.

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.

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