The effects of thoracic epidural anesthesia on hepatic blood flow in patients under general anesthesia.

BACKGROUND: Hepatic hypoperfusion is regarded as an important factor in the pathophysiology of perioperative liver injury. Although epidural anesthesia (EDA) is a widely used technique, no data are available about the effects on hepatic blood flow of thoracic EDA with blockade restricted to thoracic segments in humans. METHODS: In 20 patients under general anesthesia, we assessed hepatic blood flow index in the right and middle hepatic vein by use of multiplane transesophageal echocardiography before and after induction of EDA. The epidural catheter was inserted at TH7-9, and mepivacaine 1% with a median (range) dose of 10 (8-16) mL was injected. Norepinephrine (NE) was continuously administered to patients who demonstrated a decrease in mean arterial blood pressure below 60 mm Hg after induction of EDA (EDA-NE group). The other patients did not receive any catecholamine during the study period (EDA group). A further 10 patients without EDA served as controls (control group). RESULTS: In five patients, administration of NE was necessary to avoid a decrease in mean arterial blood pressure below 60 mm Hg. Thus, the EDA-NE group consisted of five patients and the EDA group of 15. In the EDA group, EDA was associated with a median decrease in hepatic blood flow index of 24% in both hepatic veins (P < 0.01). In the EDA-NE group, all five patients showed a decrease in the blood flow index of the right (median decrease 39 [11-45] %) and middle hepatic vein (median decrease 32 [7-49] %). Patients in the control group showed a constant blood flow index in both hepatic veins. Reduction in blood flow index in the EDA group and the EDA-NE group was significant in comparison with the control group (P < 0.05). In contrast to hepatic blood flow, cardiac output was not affected by EDA. CONCLUSIONS: We conclude that, in humans, thoracic EDA is associated with a decrease in hepatic blood flow. Thoracic EDA combined with continuous infusion of NE seems to result in a further decrease in hepatic blood flow.

Analysis of diastolic function in patients undergoing aortic aneurysm repair and impact on hemodynamic response to aortic cross-clamping.

OBJECTIVES: The purpose of this study was to analyze left ventricular diastolic function in patients undergoing aortic aneurysm repair and to investigate the effects of laparotomy and aortic cross-clamping on diastolic function. DESIGN: Prospective clinical study. SETTING: University hospital. PARTICIPANTS: Forty-five consecutive patients undergoing open aortic aneurysm repair. INTERVENTIONS: Left ventricular diastolic function and hemodynamic variables were evaluated using transesophageal Doppler echocardiography and a pulmonary artery catheter at baseline, after laparotomy, and at 1 and 10 minutes after cross-clamping. Diastolic function was determined by Doppler derivatives of mitral inflow (E/A ratio, deceleration time of early inflow) and pulmonary venous flow (S/D ratio). MEASUREMENTS AND MAIN RESULTS: Twenty of 39 patients revealed signs of diastolic dysfunction at baseline. Of these 20 patients, 14 displayed delayed relaxation and 6 displayed a pseudonormal filling pattern. Patients with pseudonormal filling exhibited a lower stroke volume (p = 0.02) and cardiac index (p < 0.01) in comparison to patients with normal diastolic function. Laparotomy was associated with an improvement of diastolic function in 9 of 20 patients with preexisting diastolic dysfunction. Only 3 patients suffered impairment of diastolic function after cross-clamping. The hemodynamic response to cross-clamping did not differ between patients with normal and abnormal diastolic function. CONCLUSIONS: About 50% of patients undergoing aortic aneurysm repair exhibit signs of diastolic dysfunction. The majority of these patients showed delayed relaxation. Patients with pseudonormal filling displayed a significantly lower cardiac index. Laparotomy resulted in an improvement in diastolic function in about half of patients with preexisting diastolic dysfunction. The effects of cross-clamping on diastolic function are minimal.

The effects of intraabdominally insufflated carbon dioxide on hepatic blood flow during laparoscopic surgery assessed by transesophageal echocardiography.

Conflicting results have been published about the effects of carbon dioxide (CO(2)) pneumoperitoneum on splanchnic and liver perfusion. Several experimental studies described a pressure-related reduction in hepatic blood flow, whereas other investigators reported an increase as long as the intraabdominal pressure (IAP) remained less than 16 mm Hg. Our goal in the present study was to investigate the effects of insufflated CO(2) on hepatic blood flow during laparoscopic surgery in healthy adults. Blood flow in the right and middle hepatic veins was assessed in 24 patients undergoing laparoscopic surgery by use of transesophageal Doppler echocardiography. Hepatic venous blood flow was recorded before and after 5, 10, 20, 30, and 40 min of pneumoperitoneum, as well as 1 and 5 min after deflation. Twelve patients undergoing conventional hernia repair served as the control group. The induction of pneumoperitoneum produced a significant increase in blood flow of the right and middle hepatic veins. Five minutes after insufflation of CO(2) the median right hepatic blood flow index increased from 196 mL/min/m(2) (95% confidence interval (CI), 140-261 mL/min/m(2)) to 392 mL/min/m(2) (CI, 263-551 mL/min/m(2)) (P < 0.05) and persisted during maintenance of pneumoperitoneum. In the middle hepatic vein the blood flow index increased from 105 mL/min/m(2) (CI, 71-136 mL/min/m(2)) to 159 mL/min/m(2) (CI, 103-236 mL/min/m(2)) 20 min after insufflation of CO(2). After deflation blood flow returned to baseline values in both hepatic veins. Conversely, in the control group hepatic blood flow remained unchanged over the entire study period. We conclude that induction of CO(2) pneumoperitoneum with an IAP of 12 mm Hg is associated with an increase in hepatic perfusion in healthy adults.

Transesophageal echocardiographic guidance of thoracic aortic stent-graft implantation.

PURPOSE: To evaluate the efficacy of intraoperative transesophageal echocardiography (TEE) as an adjunctive measure in guiding the implantation of endoluminal stent-grafts in the thoracic aorta. METHODS: TEE was used in 21 of 30 patients (27 men; median age 70 years; range 19-77) undergoing implantation of Excluder or Talent stent-grafts for management of 11 type B aortic dissections, 7 thoracic aortic aneurysms, 2 traumatic thoracic aortic ruptures, and an aortic coarctation. We evaluated the ability of TEE to provide evidence of (1) correct placement of the guidewire within the true lumen, (2) reduction in blood flow in the false lumen following stent deployment, and (3) early complications. RESULTS: Definite identification of the true lumen and a reliable evaluation of the position of the stent-graft guidewire during advancement were possible in all patients. Reduction of blood flow within the false lumen following deployment of the stent-graft was visualized in >70% of patients with aortic dissection. In the patient with aortic coarctation, TEE recognized the acute onset of aortic dissection following stent dilation, which resulted in immediate management with an additional stent. CONCLUSIONS: The intraoperative use of TEE in the implantation of stent-grafts in the thoracic aorta is not significantly invasive and is easily employed. It permits excellent evaluation of the correct placement of the stent guidewire and, in patients with aortic dissection, intraoperatively visualizes effective blood flow reduction in the false lumen following stent-graft deployment. Its ability to recognize early complications may indicate the need for additional maneuvers during the surgical procedure.