Thoracic Epidural Anesthesia Group Research Articles

Radio-frequency thermal ablation of lung cancer under epidural anaesthesia: comparison of the effectiveness of blocks between higher and mid-thoracic level

Purpose of the investigation is to evaluate the effectiveness of high thoracic epidural block in comparison to mid-thoracic epidural during Radiofrequency ablation for lung cancer. 60 patients (38 male) were selected for epidural segmental block who were proposed for radiofrequency thermal ablation for lung cancer. Patients were randomly divided in 2 groups: Group-A, higher thoracic epidural group & Group-B, mid-thoracic epidural group. Under all aseptic preparation 18 G Epidural catheter was inserted through 18 G epidural needle and 4-6 ml of 0.5% bupivacaine was used during anaesthesia. Extend of block was demarcated by pain prick. RFT probe was allowed to insert 30 minutes after anaesthesia. The heat rate, blood pressure, respiration, Sp02 and temperature were monitored continuously during the procedure. Excellent block was found in 21 cases of Group-A and 15 cases of Group-B. Anaesthesia was inadequate in two cases of Group-A, and in 5 cases of Group-B, So, Higher thoracic epidural technique is better than mid thoracic epidural.DOI: http://dx.doi.org/10.3329/jbsa.v17i1.4050 Journal of BSA, Vol. 17, No. 1 & 2, 2004 p.36-38

Epidural Anesthesia in Elderly Patients Undergoing Coronary Artery Bypass Graft Surgery

The purpose of this study was to evaluate the effects of thoracic epidural anesthesia on postoperative N-terminal pro B-natriuretic peptide (NT-proBNP) release in elderly patients undergoing elective coronary artery bypass graft (CABG) surgery. A case-matched, nonrandomized study. A university hospital, single institution. 46 consecutive and 46 control patients. Ninety-two elderly patients (>65 years old) undergoing elective CABG surgery were recruited. Forty-six patients receiving general and epidural anesthesia were case matched (preoperative medications, ejection fraction, and comorbidities) with 46 control subjects receiving general anesthesia. The primary outcome measure was postoperative NT-proBNP release. The preoperative or intraoperative variables significantly associated with an intensive care unit stay longer than 4 days were determined by logistic regression. The median (interquartile range) plasma concentrations of NT-proBNP before surgery were 402 (115-887 pg/mL) in the epidural group versus 508 (228-1,285 pg/mL) in the general anesthesia group (p = 0.9), whereas 24 hours after surgery it increased to 1846 (1,135-3,687 pg/mL) versus 5,005 (2,220-11,377 pg/mL) (p = 0.001), respectively. There were more patients (p = 0.043) in the control group (9/46 = 19.5%) than in the thoracic epidural anesthesia group (4/46 = 8.8%) with an intensive care unit stay longer than 4 days. The absence of preoperative beta-blocker therapy (odds ratio = 3.94; 95% confidence interval, 1.123-13.833; p =0.03) and of an epidural catheter (odds ratio = 3.91; 95% confidence interval, 1.068-14.619; p = 0.04) were the only preoperative and intraoperative variables independently associated with a prolonged intensive care unit stay. Epidural anesthesia added to general anesthesia for CABG surgery significantly attenuates NT-proBNP release in elderly patients and reduces the incidence of prolonged intensive care unit stay.

Thoracic epidural anesthesia reverses sepsis-induced hepatic hyperperfusion and reduces leukocyte adhesion in septic rats

IntroductionLiver dysfunction is a common feature of severe sepsis and is associated with a poor outcome. Both liver perfusion and hepatic inflammatory response in sepsis might be affected by sympathetic nerve activity. However, the effects of thoracic epidural anesthesia (TEA), which is associated with regional sympathetic block, on septic liver injury are unknown. Therefore, we investigated hepatic microcirculation and inflammatory response during TEA in septic rats.MethodsForty-five male Sprague-Dawley-rats were instrumented with thoracic epidural catheters and randomized to receive a sham procedure (Sham), cecal ligation and puncture (CLP) without epidural anesthesia (Sepsis) and CLP with epidural infusion of 15 ul/h bupivacaine 0.5% (Sepsis + TEA). All animals received 2 ml/100 g/h NaCl 0.9%. In 24 (n = 8 in each group) rats, sinusoidal diameter, loss of sinusoidal perfusion and sinusoidal blood flow as well as temporary and permanent leukocyte adhesion to sinusoidal and venolar endothelium were recorded by intravital microscopy after 24 hours. In 21 (n = 7 in each group) separate rats, cardiac output was measured by thermodilution. Blood pressure, heart rate, serum transaminase activity, serum TNF-alpha concentration and histologic signs of tissue injury were recorded.ResultsWhereas cardiac output remained constant in all groups, sinusoidal blood flow increased in the Sepsis group and was normalized in rats subjected to sepsis and TEA. Sepsis-induced sinusoidal vasoconstriction was not ameliorated by TEA. In the Sepsis + TEA group, the increase in temporary venolar leukocyte adherence was blunted. In contrast to this, sinusoidal leukocyte adherence was not ameliorated in the Sepsis + TEA group. Sepsis-related release of TNF-alpha and liver tissue injury were not affected by Sepsis + TEA.ConclusionsThis study demonstrates that TEA reverses sepsis-induced alterations in hepatic perfusion and ameliorates hepatic leukocyte recruitment in sepsis.

Thoracic Epidural Analgesia with Low Concentration of Bupivacaine Induces Thoracic and Lumbar Sympathetic Block

Clinical benefits of thoracic epidural anesthesia (TEA) are partly ascribed to thoracic sympathetic block. However, data regarding sympathetic activity during TEA are scarce and contradictory. This prospective, randomized, double-blind study evaluated the segmental propagation of sympathetic block after low-concentration, high-volume TEA using digital thermography. Twenty-four patients were included in the study. Thoracic epidural catheters were placed at a median insertion level of T8-T9. Patients were accommodated for 20 min to the room temperature of 23 degrees +/- 0.3 degrees C. Skin temperature was recorded by digital thermography. After baseline measurement of heart rate, arterial pressure, and core body and skin temperature, 10 ml saline (control group) or 10 ml bupivacaine, 0.25% (TEA group), respectively, was administered epidurally. Five minutes (t5) and 20 min (t20) after baseline measurements, hemodynamic parameters and core body temperature were again measured, and sensory block was identified by loss of cold-warm discrimination. In the thumb, the toe, and each thoracic dermatome, difference from baseline temperature was calculated at t5 and t20. Data were analyzed by Mann-Whitney U test. Baseline characteristics did not differ among groups. Median spread of sensory block at t20 was T5-L5. At both t5 and t20, skin temperature decreased more in the control group than in the TEA group in all thoracic dermatomes (P < 0.05). Toe temperature increased in the TEA group compared with the control group (P < 0.05), whereas thumb temperature remained unchanged. TEA with 10 ml bupivacaine, 0.25%, induced thoracic and lumbar sympathetic block that precedes and exceeds sensory block. Caudal limit of sympathetic block could not be demonstrated in this study.

Thoracic epidural anesthesia attenuates hemorrhagic-induced splanchnic hypo-perfusion in post-resuscitation experimental hemorrhagic shock

Angina ludwing merupakan peradangan selulitis dari bagian superior ruang suprahioid suprahioid, yang ditandai dengan pembengkakan (edema) pada bagian bawah ruang submandibula yang biasanya keras dan berwarna kemerahan atu kecoklatan. Penyebab abses ini paling sering terjadi sebagai akibat infeksi akar gigi yaknimolar dan premolar dapat juga berasal dari proses supuratif kelenjar linfe servikal di dalam ruang submandibula. Penanganan yang utama adalah menjamin jalan napas melalui trakeostomi.

Epidural Anesthesia Improves Outcome and Resource Use in Cardiac Surgery: A Single-Center Study of a 1293-Patient Cohort

Thoracic epidural anesthesia (TEA) combined with general anesthesia in cardiac surgery has the potential to initiate earlier spontaneous ventilation and extubation, improved hemodynamics, less arrhythmia or myocardial ischemia, and an attenuated neurohormonal response. The aim of the current study was to characterize the correlation between TEA and postoperative resource use or outcome in a consecutive-patient cohort. The study was performed in a tertiary care, 3-surgeon, university-affiliated hospital that performs 350 to 400 cardiac surgeries per year. All 1293 adult patients who underwent cardiac surgery between July 1, 2002, and February 1, 2006, were included. Patients were assigned to anesthesiologists practicing TEA (TEA group, n = 506) or not (control group, n = 787) for cardiac surgery. The preoperative parameter values and Parsonnet scores for the 2 groups were similar. The 2 groups had the same distribution of surgery types. The TEA group presented with fewer intensive care unit (ICU) complications, such as delirium, pneumonia, and acute renal failure, and presented with better myocardial protection. The TEA group presented with a higher proportion of immediately postoperative extubations and with shorter ventilation times and ICU stays. Total ICU costs decreased from US $18,700 to $9900 per patient. Combining TEA and general anesthesia for cardiac surgery allows a significant change in anesthesia strategy. This change improves immediate postoperative outcomes and reduces the use and costs of ICU resources.

Therapeutic administration of thoracic epidural anesthesia reduces cardiopulmonary deterioration in ovine pulmonary embolism*

It was hypothesized that sympathetic blockade restricted to the thoracic levels and achieved by thoracic epidural anesthesia might be capable of reducing hemodynamic deterioration after pulmonary artery embolism and that this might represent a potential method of treatment in patients with pulmonary embolism. Cardiopulmonary function after pulmonary embolism was therefore studied in sheep, either without a sympathetic blockade (the control group) or with sympathetic blockade. Prospective, randomized laboratory investigation. University research laboratory. Twelve adult, chronically instrumented Blackhead ewes. Pulmonary embolization was achieved by injecting autologous blood clots (0.75 mL/kg) intravenously into an external jugular vein. The treatment group (n = 6) received 6 mL of 0.175% bupivacaine and the control group (n = 6) received 6 mL of 0.9% NaCl 90 mins after the embolization procedure. The injections were made via an epidural catheter (at the level of T3). Results were considered to be statistically significant (with analysis of variance) at p < .05. After epidural administration of bupivacaine in the thoracic epidural anesthesia group, the mean pulmonary artery pressure and heart rate were significantly reduced and the stroke volume index was significantly higher in comparison with the control group, in which the animals received epidural injections of saline. Thoracic epidural anesthesia administered after the occurrence of pulmonary artery embolism thus significantly reduces hemodynamic deterioration in awake, spontaneously breathing sheep and may represent an additional option in the treatment of pulmonary embolism.

Comparison of the Modulatory Effects of Four Different Fast-Track Anesthetic Techniques on the Inflammatory Response to Cardiac Surgery With Cardiopulmonary Bypass

To test the hypothesis that the choice of anesthesia technique for coronary artery surgery influences the degree and magnitude of the subsequent inflammatory response and its consequences. Prospective, randomized, comparative study. Major university teaching hospital. Sixty patients undergoing elective surgery. Patients were randomized into an alfentanil group, a high-dose remifentanil group, a low-dose remifentanil group, or a thoracic epidural group, in combination with a propofol target-controlled infusion. The study was blinded for the opioid, except in the epidural group. Tight control of perioperative hemodynamic parameters was maintained, and the postoperative management was strictly standardized. Bactericidal permeability-increasing protein as an indicator of the polymorphonuclear neutrophil response, interleukin-6 as an inducer of the acute-phase response, and lipopolysaccharide-binding protein and C-reactive protein as parameters of the acute phase response were determined at regular intervals. Ventilator dependency and analgesia were evaluated as clinical outcome measures. Interleukin-6 levels increased in all groups. Plasma levels in the epidural group were significantly higher at all time points than in the other groups. The increase in the plasma levels of bactericidal permeability-increasing protein, lipopolysaccharide-binding protein, and C-reactive protein showed the same pattern in all groups, and no significant differences among the 4 groups were observed. Supplementation of a fast-track anesthetic technique with epidural analgesia preserves hemodynamic stability and is associated with faster extubation times (p = 0.003) and less postoperative pain (p = 0.045). Thoracic epidural analgesia was associated with significantly higher levels of IL-6 throughout the study period as compared with the total intravenous anesthesia groups. The exact clinical relevance of this finding remains unclear.

Effects of Continuous Epidural Infusion after Thoracic Epidural Anesthesia for Mastectomy on Postoperative Pain, Nausea and Vomiting

Background: Breast cancer is the most common cause of tumors in Korean women. Until recently, oncologic breast surgery was performed by using general inhalation anesthesia. However, this anesthetic method is associated with incomplete postoperative pain control and significantly more postoperative nausea and vomiting (PONV). Therefore, this study examinated the value of thoracic epidural anesthesia (TEA) for a mastectomy, and evaluated the effects of a continuous epidural infusion on postoperative pain control and the PONV, which is known to be a better method than general anesthesia with intravenous patient controlled analgesia (IV PCA). Methods: Sixty five patients scheduled for a mastectomy were randomly assigned and divided into two groups. The GA group underwent general anesthesia using O2-N2O-sevoflurane with IV PCA. The TEA group was injected with 20 ml of 0.375% ropivacaine with fentanyl 50μg at T4－5. After surgery the visual analogue scale (VAS) score of postoperative pain and nausea was checked. Results: The postoperative pain intensity was significantly (P ＜ 0.05) lower in the TEA group at the postoperative period and during 6 hours compared with the GA group. Postoperative nausea intensity was significantly (P ＜ 0.05) lower in the TEA group during 6 hours. Conclusions: These results suggest that TEA is a method suitable of regional anesthesia for a mastectomy and a continuous epidural catheter infusion is more effective on postoperative pain control than general anesthesia with IV PCA. In addition, it is a good method for decreasing the PONV to a similar level as IV PCA with antiemetics. (Korean J Anesthesiol 2007; 52: 396~402)

Prospective, randomized comparison of ketorolac vs. Thoracic epidural analgesia with non-muscle relaxant anaesthesia after thymectomy in myasthenic patients

We test the hypothesis that ketorolac or thoracic epidural anaesthesia (TEA) without neuromuscular blockers improves pain control and pulmonary functions after thymectomy in seventy five myasthenic patients. They were randomly allocated received, either a saline placebo (n=25), ketorolac 15 mg, followed by IVI for 7.5 mg.h -1 for 12 hours (n=25), or TEA with 10 mL of bupivacaine 0.5%, followed by 8 mL.h -1 of bupivacaine 0.125% for 12 hours (n=25). Anaesthesia was induced with fentanyl (1.0 μg.kg -1 ) and propofol and maintained with propofol and 67% N2O. Patients receiving ketorolac and TEA had a smaller increase in HR and MAP, lower supplementary doses of fentanyl, shorter emergence and extubation times (P<0.001), and PACU stay, lower respiratory rate, better pain control, for the first 12 postoperative hours, higher PEFR values at 1 and 6 h, and no patient had to be re-intubated postoperatively. Seven patients in TEA group needed IV ephedrine. In conclusion, the use of ketorolac is safe and might be an alternative to TEA in providing excellent intra-operative anaesthesia, early extubation, and postoperative analgesia in myasthenic patients after thymectomy. This article has won the first prize in the competition session during the cardiothoracic symposium in Cairo 12-16Feb 2007

EFFECTS OF THORACIC EPIDURAL ANESTHESIA ON HEMODYNAMICS AND GLOBAL OXYGEN TRANSPORT IN OVINE ENDOTOXEMIA

Besides providing effective analgesia, thoracic epidural anesthesia (TEA) has been shown to decrease perioperative morbidity and mortality. Because of its vasodilatory properties in association with the sympathetic blockade, however, TEA may potentially aggravate cardiovascular dysfunctions resulting from sepsis and systemic inflammatory response syndrome. The objective of the present study was to assess the effects of TEA on hemodynamics, global oxygen transport, and renal function in ovine endotoxemia. After a baseline measurement in healthy sheep (n = 18), Salmonella typhosa endotoxin was centrally infused at incremental doses to induce and maintain a hypotensive-hypodynamic circulation using an established protocol. The animals were then randomly assigned to one of two groups. In the treatment group, continuous TEA was initiated with 0.1 mL.kg of 0.125% bupivacaine at the onset of endotoxemia and maintained with 0.1 mL.kg.h. In the control group, the same amount of isotonic sodium chloride solution was injected through the epidural catheter. In the animals surviving the entire experiment (n = 7 per group), cardiac index and mean arterial pressure decreased in a dose-dependent manner during endotoxin infusion. In the TEA group, neither systemic hemodynamics nor global oxygen transport were impaired beyond the changes caused by endotoxemia itself. Urinary output was increased in the TEA group as compared with the control group (P < 0.05). In this model of endotoxic shock, TEA improved renal perfusion without affecting cardiopulmonary hemodynamics and global oxygen transport.

Peculiarities of Hemodynamic Changes During High Thoracic Epidural Anesthesia in Beating Heart Surgery

Aim: Myocardial protection during off-pump coronary artery bypass surgery is a multifactorial problem. Careful, individualized choice of graft sequence and maintenance of stable systemic hemodynamics are of central importance. Patients with coronary artery disease have a high risk of adverse cardiac outcome during and after surgery. Thoracic epidural anesthesia (TEA) aims at a more specific reversible blockade of cardiac sympathetic efferents provides effective intra- and postoperative analgesia. Methods: 82 patients (mean age 69.2±14 years) undergoing off-pump coronary surgery have been divided into 2 groups (traditional general anesthesia (50), TEA combined anesthesia (32) (Naropin). Results: In the TEA group heart rate (HR) was low (12.6%, p<0.05) compared with the group of traditional anesthesia during the construction of the anastomoses for any of the three surgical setting. Parameters of cardiac index had no difference between groups, but stroke index was higher (17.4%) in TEA group that specifies to more optimum work of heart at which the greatest duration of diastole is kept for improvement of the coronary blood flow. Myocardial oxygen consumption decreases due to decreased heart rate and low peripheral vascular resistance (11.8 %) and pulmonary vascular resistance (26.3%) in comparison with control group. Coronary perfusion pressure does not suffer in the setting of epidural blockade, no significant differences between groups were found in systemic arterial pressure. Conclusion: TEA provides better hemodynamic control and analgesia compared with traditional anesthesia. Exposure and stabilization of the three main coronary arteries during beating heart surgery does not produce any appreciable change in the systemic blood pressure and heart rate.

Comparison of three anesthetic techniques for off-pump coronary artery bypass grafting: General anesthesia, combined general and high thoracic epidural anesthesia, or high thoracic epidural anesthesia alone

This study compared general anesthesia (GA), combined GA plus thoracic epidural anesthesia (TEA), and TEA alone in patients scheduled for off-pump coronary artery bypass grafting. Prospective, nonrandomized clinical study University hospital. Ninety consenting patients undergoing beating-heart coronary artery revascularization with comparable coronary status and left ventricular function. GA (n=30) was conducted with propofol, remifentanil, and cisatracurium or combined with TEA (GA+TEA, n=30) or TEA as the sole anesthetic with ropivacaine plus sufentanil (TEA, n=30). Groups were comparable regarding the surgical approaches and the number of anastomoses. Four patients (GA, n=2; GA+TEA, n=2) who required unplanned cardiopulmonary bypass, and 4 patients in the TEA group who underwent unexpected intubation because of pneumothorax (n=2), phrenic nerve palsy, or incomplete analgesia were excluded from further analysis. Intraoperative heart rate decreased significantly with both GA+TEA and TEA. None of the patients with TEA alone was admitted to the intensive care unit, they all were monitored on average for 6 hours postoperatively in the intermediate care unit and allowed to eat and drink as desired on admission. Postoperative pain scores were lower in both groups with TEA. There were no differences among groups in patients overall satisfaction. Based on the authors data, all anesthetic techniques were equally safe from the clinicians standpoint. However, GA+TEA appeared to be most comprehensive, allowing for revascularization of any coronary artery, providing good hemodynamic stability and reliable postoperative pain relief. Nonetheless, the actual and potential risks of TEA during cardiac surgery should not be underestimated.

Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation

Background. To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG). Methods. Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively. Results. Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients ( p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine ( p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y ( p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery ( p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients ( p = 0.004 versus p = 0.86). Conclusions. TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.

Continuous Thoracic Epidural Anesthesia with 0.2% Ropivacaine Versus General Anesthesia for Perioperative Management of Modified Radical Mastectomy

We evaluated in this prospective study the effectiveness of continuous thoracic epidural anesthesia (TEA) and postoperative analgesia with ropivacaine and compared it with general anesthesia (GA) and opioids for pain relief, side effects, postanesthesia recovery, and hospital discharge after modified radical mastectomy. Sixty ASA physical status II and III patients undergoing mastectomy were randomly assigned to two study groups of 30 patients each. In the TEA group, an epidural catheter was inserted at T6-7, and 5--10 mL of 0.2% ropivacaine was injected to maintain anesthesia and to continuously administer adequate analgesia for 48 h. GA was induced with IV 1--2 mg of midazolam or 50--100 microg/mL of fentanyl followed by 50--150 mg of propofol and was maintained with sevoflurane and 50% N(2)O in oxygen. The Aldrete score system was used to evaluate postanesthesia recovery, a verbal rating scale was used for assessment of pain intensity, and a postanesthesia discharge scoring system was used for discharge home. The demographic data and side effects (except for nausea and vomiting) (GA 43%, TEA 10%, P = 0.0074) and discharge home were similar in both groups. However, the number of patients ready for discharge from the recovery room during the first postanesthesia hour (Aldrete score of 10) was significantly larger after TEA (80%) than after GA (33%) (P = 0.0006). GA patients experienced significantly more (P < 0.001) substantial pain than TEA patients on Day 0 (70%), Day 1 (53%), and Day 2 (27%) after the surgery. Patient satisfaction was greater with TEA (70%) than with GA (30%) (P < 0.001). We conclude that TEA with ropivacaine provides better postoperative pain relief and less nausea and vomiting, facilitates postanesthesia recovery, and gives greater patient satisfaction than GA.

Thoracic Epidural Anesthesia Combined with General Anesthesia: The Preferred Anesthetic Technique for Thoracic Surgery

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. 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.

Chronic Pain: Management Strategies That Work

Chronic Pain: Management Strategies That Work

Thoracic epidural anesthesia increases mucosal perfusion in ileum of rats.

Previous studies reported that thoracic epidural anesthesia (TEA) protected against a decrease in gastric intramucosal pH, suggesting that TEA increased gut mucosal perfusion. The current study examines the effects of TEA on ileal mucosa using intravital microscopy in anesthetized rats. Nineteen rats were equipped with epidural catheters, with the tip placed at T7 through T9. Rats were anesthetized and mechanically ventilated. After midline abdominal incision, the ileum was prepared for intravital microscopy. Videomicroscopy on the ileal mucosa was performed before and after epidural infusion of 20 microliter of bupivacaine 0.4% (TEA group, n = 11 rats) or normal saline (control group, n = 8 rats). Microvascular blood flow in ileum mucosa was assessed offline using computerized image analysis. Control rats exhibited unchanged mean arterial pressure and microvascular perfusion. During TEA, mean arterial pressure was decreased compared with the control group (93 +/- 10 vs. 105 +/- 9 mmHg; P < 0.05). Epidural bupivacaine increased red cell velocity in terminal arterioles from 888 +/- 202 to 1,215 +/- 268 micrometer/s (control, 793 +/- 250 to 741 +/- 195 micrometer/s; P < 0.001 between groups). Because arteriolar diameter was not affected, this increase in red cell velocity may represent an increase in arteriolar blood flow. Total intercapillary area (inversely related to perfused capillary density) was unchanged, but for the TEA group the difference between total intercapillary area and the intercapillary area calculated for continuously perfused capillaries was decreased compared with the control group (16 +/- 12 vs. 40 +/- 19%; P < 0.001), indicating a decrease in intermittent (stop-and-go) blood flow in the villus microcirculation. Thoracic epidural anesthesia increased gut mucosal blood flow and reduced intermittent flow in the villus microcirculation in the presence of a decreased perfusion pressure.

Can the Results be Explained by Poor Randomization and Nonpertinent Comparisons?

To the Editor: I am writing regarding the article, “Anti-Ischemic and Anti-Anginal Effects of Thoracic Epidural Anesthesia Versus Those of Conventional Medical Therapy in the Treatment of Severe Refractory Unstable Angina Pectoris” by Olausson et al.1 While doing comparative graphs for a lecture, I found several inconsistencies in the article that diminish its scientific value. The main inconsistency is found in Table 1. During a run-in period, the patients were treated with both nitroglycerin and heparin infusions for 82±18 versus 122±20 and 53±7 versus 104±13 hours, respectively, for controls and the group with thoracic epidural anesthesia (TEA). These differences were reported as nonsignificant by the authors. However, when recalculating the statistics, I found values of P <0.14 and P <0.0015 for the nitroglycerin and heparin infusions, respectively. Thus, at least in terms of the heparin infusion, it seems that the patients might not have been properly randomized. In addition, Tables 2 and 3 contain several inconsistencies. …

Arterial Oxygenation During One-Lung Ventilation: Combined Versus General Anesthesia

We read with interest the study by Garutti et al. (1), in which they demonstrated that thoracic epidural anesthesia (TEA) during one-lung ventilation (OLV) in the lateral decubitus position increases intrapulmonary shunt and decreases PaO2. However, we feel that the conclusion that TEA cannot be recommended in patients undergoing OLV is unjustified by their findings. The larger intrapulmonary shunt during TEA is an interesting phenomenon that we have also observed in patients undergoing coronary artery bypass grafting using high TEA at the T1-T2 level (T.H.L., unpublished data, 1998). However, in the study by Garutti et al. (1), subsequent lower PaO2 in the TEA group compared with the general anesthesia (GA) group did not lead to hypoxemia (PaO2 117 ± 57 mm Hg in the TEA group after 30 min). Indeed, three patients in the GA group presented with values of PaO2 < 70 mm Hg compared with two patients in the TEA group. Therefore, although PaO2 values show statistically significant differences, they do not appear to lead to clinically important differences. However, there is significant evidence that using TEA intra- and postoperatively for thoracotomy or sternotomy results in fewer postoperative complications, superior postoperative bloodgasses, and increased patient comfort (2,3). We feel that these factors outweigh decreased PaO2 levels during the operation, for which there are several treatment strategies available (4). In our practice, we usually combine TEA with bupivacaine/morphine and GA with isoflurane, which is known to also attenuate hypoxic pulmonary vasoconstriction, and hypoxemia during OLV is rarely a problem. Although we understand that the combination of GA, TEA, and OLV has many facets, which have to be elucidated one by one, we have to keep our eyes on the big picture. We therefore feel that the conclusion that TEA cannot be recommended in patients undergoing OLV may not be made by looking at only one aspect. W. Anton Visser MD Tiong H. Liem MD, PhD Mathieu J. M. Gielen MD, PhD