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Signa Vitae

Journal of Intensive Care and Emergency Medicine

Hypoxia during one lung ventilation in thoracic surgery

Abstract

Background. The technique of one lung ventilation (OLV) is used with the purpose of achieving isolation of the diseased lung being operated upon, using a double-lumen endobronchial tube. Thoracic surgical procedures which are performed in the lateral decubitus position, nowadays could not be imagined without OLV. In spite of advantages regarding surgical exposure, OLV is associated with serious respiratory impairment. Hypoxemia is considered to be the most important challenge during OLV. The goal of this study was to establish the magnitude of intrapulmonary shunt, as well as the immensity of hypoxia during general anesthesia with OLV.

Materials and Methods. In this prospective interventional clinical study thirty patients were enrolled who underwent elective thoracic surgery with a prolonged period of OLV. The patients received balanced general anesthesia with fentanyl/propofol/rocuronium. A double-lumen endobronchial tube was inserted in all patients, and mechanical ventilation with 50% oxygen in air was used during the entire study. Arterial blood gases were recorded in a lateral decubitus position with two-lung ventilation, at the beginning of OLV (OLV 0) and at 10 and 30 min. (OLV 10, OLV 30, respectively) after initiating OLV in all patients. Standard monitoring procedures were used. Arterial oxygenation (PaO2), arterial oxygen saturation (SaO2) and venous admixture percentage – intrapulmonary shunt (Qs/Qt %) were measured, as well as mean arterial pressure and heart rate during the same time intervals. For the purpose of this study, the quantitative value of Qs/Qt% was mathematically calculated using the blood gas analyser AVL Compact 3. A p value <0.05 was taken to be statistically significant.

Results. When OLV was instituted, arterial oxygenation decreased, whereas Qs/Qt% increased, about 10 min. after commencement, with improvement of oxygenation approximately half an hour afterwards. A statistically relevant difference (p<0.05) occurred in PaO2, SaO2 and Qs/Qt at the different time points.

Conclusion. Hypoxia during OLV, with an increase in Qs/Qt, usually occurs after 10 min. of its initiation. After 30 min, the values of the Qs/Qt ratio regularly return to normal levels.

Key words: one-lung ventilation, thoracic surgery, venous admixture, intrapulmonary shunt

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Anti-inflammatory action of sevoflurane in lung surgery with one lung ventilation

Background

In patients undergoing lung surgery mechanical ventilation and surgical trauma may induce alveolar and systemic inflammatory response. One-lung ventilation (OLV) has become as a standard procedure in thoracic surgery. It is also the main cause of acute inflammatory response and is associated with ALI and ARDS.

Demonstrating the influence of volatile anaesthetics on the inflammatory response and the treatment outcome in patients undergoing lung surgery with one lung ventilation (OLV) is still a great challenge.

The effects of sevoflurane on local release of inflammatory cytokines has been shown before. The added value of our study is that the systemic immunomodulatory effect of sevoflurane, postoperative clinical outcome and complications were tested.

The aim of the study was to prospectively investigate the systemic anti-inflammatory effect of the volatile anaesthetic sevoflurane in patients undergoing lung surgery with OLV.

Key words: one-lung ventilation, sevoflurane, inflammation

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The influence of thoracic epidural anesthesia on intrapulmonary shunt during one lung ventilation in thoracic surgery

Background: The most favorable anesthetic technique for patients undergoing thoracotomy with one lung ventilation (OLV) has not been yet certainly established. The effect of intraoperative thoracic epidural anesthesia (TEA) with local anesthetics on hypoxic pulmonary vasoconstriction (HPV) and oxygenation during thoracic surgery and OLV still remains unclear. The aim of this study was to assess the venous admixture (shunt) during general anesthesia (GA) and OLV, in combination of TEA and GA with OLV, as well as to compare the values of the shunt obtained for the duration of both anesthetic techniques.

Keywords: one-lung ventilation, epidural anesthesia, venous admixture

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Haemodynamic changes after induction of anaesthesia with sevoflurane vs. propofol

Abstract

Inhalation induction with sevoflurane would appear to offer several objective advantages compared to  induction with propofol. In our study, the hemodynamic results of sevoflurane vs. propofol induction in patients undergoing thoracotomy were studied. In a prospective, randomized, blinded study 24  patients were randomly allocated to one of 2 groups: sevoflurane (S) and propofol (P) (n=12 each). For  hemodynamic monitoring the LIDCO plus system was used. Patients in  group S were induced into anaesthesia with sevofluran, remifentanil and vecuronium, whereas patients in group P with propofol, remifentanil and vecuronium. The anaesthesia was maintained with the same agents. Hemodynamic stability was guided using a special algorithm. The goal was oxygen delivery index (DO2I) > 500 mL min-1 m-2. According to the algorithm, patients received colloids or vasoactive drugs. Hemodynamic parameters were recorded before induction, 3 minutes after induction and 3 minutes after intubation and commencement of  one lung ventilation. The consumption of vasoactive drugs and colloids and the time from the beginning of  induction to intubation were documented. No statistically significant differences in measured hemodynamic parameters, remifentanil and colloid consumption between the S and P group were found. In group P, statistically more ephedrine was used (S: 4.2, P:20.8, p<0.05). Patients undergoing thoracotomy induced with sevoflurane are circulatory more stable than those induced with propofol.

Key words: thoracotomy, one lung ventilation, cardiac index,  Systemic Vascular Resistance Index (SVRI)

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