Table 3.
Human studies
| Ref. | Year | Title | Type of study | Scenario | No. subjects | Sensory blockade | Surrogate measure of splanchnic flow | Findings |
| Lundberg et al[19] | 1990 | Intestinal hemodynamics during laparotomy: effects of thoracic epidural anesthesia and dopamine in humans | Prospective observational | Patients undergoing abdominal aorto-bifemoral reconstruction | 9 | Catheter inserted T7-T8 or T8-T9 and advanced 2-3 cm | Superior mesenteric artery blood flow (SMABF) via electromagnetic flow probe, mesenteric arteriovenous oxygen difference mesenteric venous lactate | ↓ SMABF and ↓ MAP only restored by dopamine infusion |
| Tanaka et al[23] | 1997 | The effect of dopamine on hepatic blood flow in patients undergoing epidural anesthesia | Prospective controlled | Patients ASA 1-2 undergoing elective gynecological surgery. Normotension maintained either with HES infusion or HES + dopamine | 28 (7 no TEA vs 14 TEA + HES vs 7 TEA + HES + dopamine) | Upper T5 | Hepatic blood flow using Plasma Disappearance Rate of indocyanine green (PDR-icg) | ↓ PDR-icg in TEA + HES group, = PDR-icg in TEA + HES + dopamine group |
| Väisänen et al[25] | 1998 | Epidural analgesia with bupivacaine does not improve splanchnic tissue perfusion after aortic reconstruction surgery | Prospective randomized controlled | Patients undergoing elective aortic reconstruction surgery | 20 (10 TEA vs 10 controls) | Catheter inserted T12-L1 and advanced 5 cm | Gastric and sigmoid mucosal PCO2, pHi. Splanchnic blood flow direct invasive measure by cannulation of hepatic vein and dye diluition method (indocyanine green) | No differences |
| Spackman et al[26] | 2000 | Effect of epidural blockade on indicators of splanchnic perfusion and gut function in critically ill patients with peritonitis: a randomised comparison of epidural bupivacaine with systemic morphine | Double-blinded, prospective, randomised, controlled | Critically ill patients admitted in ICU with peritonitis (and systemic sepsis) and adynamic small bowel following abdominal surgery | 21 (10 intravenous morphine vs 11 epidural bupivacaine) | Low thoracic or high lumbar epidural catheter insertion | Gastric tonometry: gastric intramucosal pH (pHig) and the intramucosal-arterial PCO2 gradient (Pg-PaCO2) | Significant improvements in gastric mucosal perfusion (a rise in Pg-PaCO2 and a fall in pHig in the morphine group and a significant difference between groups in the Pg-PaCO2 trends) and in the ultrasound appearance of the small bowel in the epidural group |
| Gould et al[20] | 2002 | Effect of thoracic epidural anaesthesia on colonic blood flow | Prospective observational | Patients undergoing elective anterior resection for rectal cancer | 15 | Cahteter inserted T9-T10 | Doppler flowmetry for inferior mesenteric artery flow and Laser Doppler flowmetry for serosal red cell flux | ↓ inferior mesenteric artery flow and ↓ serosal red cell flux significantly correlated to ↓ MAP reverted only by vasoconstrictors usage |
| Michelet et al[22] | 2007 | Effect of thoracic epidural analgesia on gastric blood flow after oesophagectomy | Prospective controlled | Patients undergoing elective radical oesophagectomy, postoperative evaluation | 27 (18 TEA vs 9 controls) | C8-T11 | Gastric mucosal blood flow (GMBF) measured using laser Doppler flowmetry at 1 and 18 h post surgery | ↑GMBF in TEA group without correlation with MAP or CI |
| Kortgen et al[27] | 2009 | Thoracic but not lumbar epidural anaesthesia increases liver blood flow after major abdominal surgery | Prospective | Patients undergoing major abdominal surgery | 34 (17 TEA vs 17 LEA) | Thoracic catheters between T5-T6 and T9-T10, lumbar catheters between L1-L2 and L4-L5 | Blood lactate levels, central venous oxygen saturation (ScvO2), PDR-icg | TEA but not LEA ↑ PDR-icg |
| Meierhenrich et al[21] | 2009 | The effects of thoracic epidural anesthesia on hepatic blood flow in patients under general anesthesia | Prospective controlled | Patients undergoing major pancreatic surgery | 30 (15 TEA vs 5 TEA + Norepinephrine vs 10 no TEA) | T4-T11 | Hepatic blood flow index and hepatic stroke volume index in the right and middle hepatic vein by use of multiplane TEE | ↓ Hepatic venous blood flow. The combination of thoracic TEA with continuous infusion of NE seems to induce a further decrease in hepatic blood flow. CO was not affected by TEA |
| Trepenaitis et al[24] | 2010 | The influence of thoracic epidural anesthesia on liver hemodynamics in patients under general anesthesia | Prospective randomized | Patients undergoing upper abdominal surgery for carcinoma of the stomach, papilla of Vater, and pancreas | 50 (40 TEA vs 10 controls) | T5-T12 | Hepatic blood flow using Plasma Disappearance Rate of indocyanine green (PDR-icg) | ↓ PDR-icg in TEA group, even if ephedrine was administered to correct hypotension. ↑ PDR-icg in patients receiving general anetshesia. CO was unaffected |
↑: Increase; ↓: Decrease. HES: Hydroxyethyl starch; NE: Norepinephrine; TEA: Thoracic epidural anesthesia; TEE: Transesophageal echocardiography.