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

UNLABELLED: 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.

[The accuracy of 4 different oximeters for continuous monitoring of mixed venous oxygen saturation during abdominal aortic surgery]. / Genauigkeit von vier verschiedenen Oxymetern zum kontinuierlichen Monitoring der gemischtvenösen Sauerstoffsättigung bei abdominellen Aorteneingriffen.

Several systems for mixed-venous oximetry are now available. There are one three-wave-length system (Abbott) and three two-wave-length systems with (Spectramed) and without automatic correction for hemoglobin or hematocrit (Edwards). The purpose of this prospective randomized study was to compare the different systems and to examine the accuracy of continuous mixed-venous oximetry during abdominal aortic surgery. Eighty patients had a radial artery cannula and one of the following fiberoptic pulmonary artery catheters inserted before induction of anesthesia: Swan-Ganz oximetry TD catheter (Edwards), Swan-Ganz flow-directed oximetry thermodilution paceport catheter (Baxter, Edwards Division), SpectraCath STP (Spectramed), and Opticath (Abbott). Mixed-venous O2 saturation was monitored by oximetry computers: SAT-1 (Edwards), SAT-2 (Baxter, Edwards Division), Hemopro2 (Spectramed), and Oximetrix 3 (Abbott). As a method of reference, mixed-venous blood samples were drawn and immediately analyzed by an OSM3-Hemoximeter. Data sets were obtained at eight predetermined times. Hemoglobin was kept constant at +/- 1 g.dl-1. Continuous oximetry in comparison to in-vitro measurements yielded a correlation coefficient of r = 0.873 (P less than 0.0001) and a value of bias and precision (b +/- p) of -0.9 +/- 2.6% for the SAT-1, r = 0.815 (P less than or equal to 0.0001) and b +/- p = -2.2 +/- 2.5% for the SAT-2, r = 0.901 (P less than or equal to 0.0001) and b +/- p = 0.35 +/- 2.5% for the Hemopro2, and r = 0.920 (P less than or equal to 0.0001) and b +/- p = 0.1 +/- 1.8% for the Oximetrix 3, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[A comparison of enflurane and propofol in thoracic surgery]. / Vergleich von Enfluran und Propofol bei thoraxchirurgischen Eingriffen.

Comparisons between propofol and inhalational anesthetics for maintenance of anesthesia are limited. The purpose of our prospective study was to examine differences between enflurane and propofol during pulmonary resections with one-lung ventilation (1LV). METHOD. 28 patients, ASA risk group II-III, gave written informed consent for inclusion in this institutionally approved study. The patients were randomly allocated to one of the following groups: A: propofol 10 mg kg-1 h-1, B: 1 MAC enflurane, for maintenance of anesthesia. In both groups analgesia was achieved by fentanyl and muscle relaxation, by pancuronium. Ventilation via a double-lumen tube was controlled (FiO2 = 1.0, PaCO2 35-40 mmHg). Measurements, including hemodynamics and arterial and mixed venous blood gases, were obtained before induction (I), during two-lung ventilation (2LV) 15 min after induction in the supine position (II) and 20 min after surgical opening of the chest in the lateral decubitus position (III), 20 min after starting 1LV (IV), and after extubation (V). RESULTS. No significant differences between the two groups were found before induction (I), during 2LV (II, III), or after extubation (V). The only significant differences between the two groups were observed during 1LV (IV): the shunt fraction was 33.9 +/- 2.5% in A and 38.5 +/- 2.6% in B (P less than or equal to 0.05). Hypoxic pulmonary vasoconstriction was not inhibited in A, but was inhibited by 21.5% in group B during 1LV. Since no case of hypoxemia occurred in group A during 1LV (range of PaO2: 75.2-417.0 mmHg), but four patients developed hypoxemia in group B (Range of PaO2: 46.6-431.0 mmHg), regimen A might be of value in high-risk patients during thoracic surgery when 1LV is planned.

Value and accuracy of dual oximetry during pulmonary resections.

During thoracic surgery, one-lung ventilation (1LV) is often required. The purpose of this prospective study was to examine the usefulness and accuracy of dual-oximetry during 1LV. Prior to the induction of anesthesia, 30 patients had a radial artery and a fiberoptic pulmonary artery catheter (15 Edwards, 15 Spectramed by randomization) inserted. Arterial O2 saturation (SpO2) was monitored by pulse oximetry, and mixed venous O2 saturation (SvO2) by oximetry (Edwards or Spectramed). Arterial and mixed venous blood gases were obtained and immediately analyzed by an OSM3-Hemoximeter. Measurements, including hemodynamics and blood gases, were obtained before induction, during two-lung ventilation (2LV) in the supine and lateral decubitus positions, during 1LV, and following extubation. The change from 2LV to 1LV was associated with significant increases in cardiac index (CI) and oxygen delivery index (DO2I), whereas PaO2 and arterial and mixed venous oxygen saturation decreased. The ratio of oxygen consumption to delivery remained stable. Continuous oximetry when compared with in vitro measurements yielded a correlation coefficient for arterial oxygen saturation of r = 0.794 (P less than or equal to 0.001) and a value of bias and precision of -0.5% +/- 1.7%; for mixed venous oxygen saturation of r = 0.874 (P less than or equal to 0.001) and -1.3% +/- 2.8% for the two-wavelength Edwards catheter; and, r = 0.862 (P less than or equal to 0.001) and -0.1% +/- 3.2% for the two-wavelength Spectramed catheter. These findings demonstrate that dual-oximetry is an on-line, reliable method to measure SpO2 and SvO2. SpO2 less than 95% reflects hypoxygenation and hypoxia (PaO2 less than or equal to 70 mm Hg). SvO2 is determined primarily by oxygenation (r = 0.005; P less than or equal to 0.05) rather than by CI (r = 0.001, ns). Since DO2I increased during 1LV to maintain the oxygen supply and demand balance, SvO2 monitoring might be useful as an early indicator in identifying high-risk patients with compromised DO2I resulting from decreased CI.