Georgia Kostopanagiotou

Hemodynamic interaction between portal vein and hepatic artery flow in small-for-size split liver transplantation.

Abstract.In split-liver transplantation, the entire portal flow is redirected through relatively small-for-size grafts. It has been postulated that excessive portal blood flow leads to graft injury. In order to elucidate the mechanisms of this injury, we studied the hemodynamic interactions between portal vein- and hepatic artery flow in an experimental model in pigs. Six whole pig liver grafts were implanted in Group 1 (n=6) and six whole liver grafts were split into right and left grafts and transplanted to Groups 2 (n=6) and 3 (n=6), respectively. The graft-to-recipient liver volume ratio was 1:1, 2:3 and 1:3 in Groups 1, 2 and 3, respectively. Portal vein- and hepatic artery flows were measured with an ultrasonic flow meter at 60,120 and 180min after graft reperfusion. Portal vein pressure was also recorded at the same time intervals. Graft function was assessed at 3,6h and 12h, and morphological changes at 12h after reperfusion. Following reperfusion, portal vein flow showed an inverse relationship to graft size, while hepatic artery flow was reduced proportionately to graft size. The difference was significant among the three groups (P<0.05). Portal vein pressure was significantly higher in group 3, compared to groups 1 and 2 (P<0.05). Hepatic artery buffer response was significantly higher in Group 3, compared to Groups 1 and 2 in relation to pre-occlusion values (P<0.05). Split-liver transplantation, when resulting in small-for-size grafts, is associated with portal hypertension, diminished arterial flow, and graft dysfunction. Arterial flow impairment appears to be related to increased portal vein flow.

A Prospective Comparison of Continuous Wound Infiltration with Ropivacaine Versus Single-Injection Paravertebral Block After Modified Radical Mastectomy

BACKGROUND: The efficacy of continuous wound infiltration with local anesthetic has not been compared with that of thoracic paravertebral block (PVB) after breast surgery. In this study, we evaluated the analgesic efficacy and morphine consumption of the two techniques after mastectomy. METHODS: Forty-eight patients undergoing modified radical mastectomy with axillary dissection were randomly assigned to either a preoperative PVB with 20 mL of ropivacaine 0.5% (group PVB) or a continuous ropivacaine 0.5% infusion (CRI) at a 2 mL/h rate for each of two multilumen catheters placed subcutaneously at the end of the procedure (group CRI). The catheters were left in place for 24 h postoperatively. A standardized general anesthetic was administered to all patients. Postoperative morphine consumption, pain scores and painful restricted movement of the shoulder for 24 h postoperatively as well as incidence of adverse events, including postoperative nausea and vomiting, were recorded. RESULTS: Morphine consumption was similar between groups (PVB: 42.6 ± 11 vs CRI: 38.7 ± 11 mg in 24 h, P = 0.225). Absolute pain scores were low in both groups. Four hours after surgery, group PVB showed a significant reduction in postoperative pain (PVB: 0 [0–10] vs CRI: 0 [0–30], P = 0.002) and reduced painful restricted movement (P = 0.004), whereas the CRI group had lower pain scores (PVB: 10 [0–30] vs CRI: 0 [0–20], P = 0.034) and painful restricted movement (P = 0.043) 16 and 24 h (PVB: 10 [0–30] vs CRI: 0 [0–30], P = 0.012) after surgery. Postoperative nausea and vomiting was significantly more frequent in the CRI group (P = 0.017). CONCLUSIONS: Continuous wound infiltration of local anesthetics is an effective alternative to paravertebral analgesia after mastectomy with axillary dissection.

Total versus selective hepatic vascular exclusion in major liver resections

BACKGROUND Total hepatic vascular exclusion (THVE) and selective hepatic vascular exclusion (SHVE) are two effective techniques for bleeding control in major hepatic resections. Outcomes of the two procedures were compared. METHODS Patients undergoing major liver resection were randomly allocated to the THVE and SHVE groups. Intraoperative hemodynamic changes and the postoperative course of the two groups were compared. RESULTS During vascular clamping, the THVE group showed a significant elevation in pulmonary vascular resistance, systemic vascular resistance, intrapulmonary shunts, and a significant reduction in cardiac index, compared with the SHVE group (P <0.05). Patients undergoing THVE received more crystalloids and blood, showed more severe liver, renal and pancreatic dysfunction, and had a longer hospital stay than the SHVE group (P <0.05). CONCLUSIONS Both techniques are equally effective in bleeding control in major liver resections. THVE is associated with cardiorespiratory and hemodynamic alterations and may be not tolerated by some patients. SHVE is well tolerated with fewer postoperative complications and shorter hospitalization time.

Anesthetic and perioperative management of adult transplant recipients in nontransplant surgery.

E ach year, .16,000 patients receive whole organ transplants in the United States alone, and this number is expected to increase yearly (1). Because the 1-yr survival rate for most transplant recipients is approaching 80%–90% and continues to improve annually, an increasing number of patients who received a transplant present for either elective or emergency nontransplant surgery (2–4). Therefore, anesthesiologists and surgeons are often required to manage transplant recipients in hospitals that are not otherwise involved in transplantation procedures. The general considerations related to any transplant recipient are the physiological and pharmacological problems of allograft denervation, the side effects of immunosuppression, the risk of infection, and the potential for rejection.

Long chain versus medium chain lipids in patients with ARDS : effects on pulmonary haemodynamics and gas exchange

Objective: To compare pulmonary haemodynamic and gas exchange alterations in septic patients with ARDS receiving long-chain triglycerides (LCT) versus medium-chain triglycerides (MCT). Design: Prospective, randomised, clinical study. Setting: Surgical ICU patients in a University Hospital. Patients: Twenty-one septic patients with ARDS were randomly assigned to receive 50 % of their non-protein caloric requirements as either 20 % LCT (group 1, n = 10) or 20 % 1 : 1 mixture of LCT/MCT (group 2, n = 11). Intervention: Intravenous infusion of LCT and LCT/MCT combinations at a rate of 12 g · h− 1. Measurements and results: The LCT infusion was associated with an increase of pulmonary venous admixture (Qva/Qt) from 24 % ± 5 % to 37 % ± 6 %, an increase of mean pulmonary artery pressure (MPAP) from 25 ± 5 to 33 ± 4 mmHg and decrease of PaO2/FIO2 from 240 ± 30 to 180 ± 35. LCT/MCT administration was only associated with an elevation of oxygen consumption (VO2) from 329 ± 14 to 396 ± 12 ml/min. During lipid infusion group 1 patients presented higher Qva/Qt (37 % ± 6 % vs 25 % ± 4 %), MPAP (33 ± 4 vs 27 ± 3 mmHg) and VO2 (359 ± 11 vs 396 ± 12 ml/min) and lower PaO2/FIO2 (180 ± 35 vs 235 ± 30) values compared to group 2. Conclusion: In conclusion, we have shown that, in septic patients with respiratory failure, LCT administration was associated with more significant changes of Qva/Qt, MPAP and PaO2/FIO2 compared to infusion of an LCT/MCT 1 : 1 emulsion. Clinically, these transient alterations might cause serious problems in patients with marginal arterial oxygenation and cardio-respiratory impairment.

Anatomy and clinical implications of the ultrasound-guided subsartorial saphenous nerve block.

Background: We evaluated the anatomic basis and the clinical results of an ultrasound-guided saphenous nerve block close to the level of the nerves exit from the inferior foramina of the adductor canal. Methods: The anatomic study was conducted in 11 knees of formalin-preserved cadavers in which the saphenous nerve was dissected from near its exit from the inferior foramina of the adductor canal. The clinical study was conducted in 23 volunteers. Using a linear probe, the femoral vessels and the sartorius muscle were depicted in short-axis view at the level where the saphenous nerve exits the inferior foramina of the adductor canal. Ten milliliters of 1.5% lidocaine was injected into the compartment structured by the sartorius muscle and the femoral artery. Results: The saphenous nerve was found to exit the adductor canal from its inferior foramina in 9 (81.8%) of 11 and at a more proximal level in 2 (18.2%) of 11 of the anatomic specimens. In a single specimen (9%), the saphenous nerve was formed by the anastomosis of 2 branches. In all the dissections, the saphenous nerve, after exiting the adductor canal, passed between the sartorius muscle and the femoral artery. Of the 23 volunteers, 22 responded with a complete sensory block, whereas a single volunteer demonstrated no sensory blockade. None of the volunteers experienced a motor block of the hip flexors and knee extensors. Conclusions: Ultrasound-guided injection directly caudally from the inferior foramina of the adductor canal, between the sartorius muscle and the femoral artery, seems to be an effective approach for saphenous nerve block.

Therapeutic value of melatonin in an experimental model of liver injury and regeneration

Abstract:  Melatonin has marked antioxidant properties. The aim of the present study was to evaluate the therapeutic effect of melatonin on acute liver injury induced in rats by carbon tetrachloride (CCl4), allyl alcohol (AA) and their combination. A total of 108 male Wistar rats were divided into 12 experimental groups according to their treatment regimen (n = 5–10 rats in each group). Melatonin (100 mg/kg body weight, BW) was administered 6 hr (a) after a single dose of CCl4 (intragastrically 0. 66 mL/kg BW diluted 1:1 v/v with corn oil); (b) a single dose of AA (intraperitonealy, 0.62 mmol/kg BW 1:50 v/v in 0.9% saline solution); and (c) a combination of the above substances. Rats were sacrificed at 24 and 48 hr post‐toxin administration and the therapeutic effect of melatonin was investigated by assessment of histopathological changes and lipid peroxidation alterations determined by measuring tissue malondialdehyde plus 4‐hydroxy‐nonenal (MDA + 4‐HNE), plasma MDA and plasma levels of liver enzymes. The levels of a key antioxidant, glutathione (GSH), were measured in liver tissue homogenates. Hepatic necrosis was significantly reduced in the melatonin‐treated rats 48 hr after administration of CCl4, AA and CCl4 + AA. The levels of hepatic enzymes in plasma were found to be significantly reduced at 24 and 48 hr in the CCl4 + AA treated rats after melatonin administration. Additionally, MDA and MDA + 4‐HNE concentrations were significantly reduced at 24 and 48 hr time‐points in all groups that received melatonin. GSH levels were decreased in liver after the toxic substances administration, whereas melatonin reversed this effect. In conclusion, a single dose of melatonin decreased hepatic injury induced by CCl4, AA and CCl4 + AA. The inhibition of the oxidative stress and therefore lipid peroxidation by melatonin in CCl4 and AA administered animals, may constitute the protective mechanism of melatonin against acute liver injury.

Time-dependent changes in the expression of thyroid hormone receptor α1 in the myocardium after acute myocardial infarction: possible implications in cardiac remodelling

The present study investigated whether changes in thyroid hormone (TH) signalling can occur after acute myocardial infarction (AMI) with possible physiological consequences on myocardial performance. TH may regulate several genes encoding important structural and regulatory proteins particularly through the TR alpha 1 receptor which is predominant in the myocardium. AMI was induced in rats by ligating the left coronary artery while sham-operated animals served as controls. This resulted in impaired cardiac function in AMI animals after 2 and 13 weeks accompanied by a shift in myosin isoforms expression towards a fetal phenotype in the non-infarcted area. Cardiac hypertrophy was evident in AMI hearts after 13 weeks but not at 2 weeks. This response was associated with a differential pattern of TH changes at 2 and 13 weeks; T(3) and T(4) levels in plasma were not changed at 2 weeks but T(3) was significantly lower and T(4) remained unchanged at 13 weeks. A twofold increase in TR alpha 1 expression was observed after 13 weeks in the non-infarcted area, P<0.05 versus sham operated, while TR alpha 1 expression remained unchanged at 2 weeks. A 2.2-fold decrease in TR beta 1 expression was found in the non-infarcted area at 13 weeks, P<0.05, while no change in TR beta 1 expression was seen at 2 weeks. Parallel studies with neonatal cardiomyocytes showed that phenylephrine (PE) administration resulted in 4.5-fold increase in the expression of TR alpha 1 and 1.6-fold decrease in TR beta 1 expression versus untreated, P<0.05. In conclusion, cardiac dysfunction which occurs at late stages after AMI is associated with increased expression of TR alpha 1 receptor and lower circulating tri-iodothyronine levels. Thus, apo-TR alpha 1 receptor state may prevail contributing to cardiac fetal phenotype. Furthermore, down-regulation of TR beta 1 also contributes to fetal phenotypic changes. alpha1-adrenergic signalling is, at least in part, involved in this response.

Propofol prevents lung injury following intestinal ischemia-reperfusion.

BACKGROUND The antioxidant properties of propofol have been shown to improve ischemia/reperfusion injury. We investigated whether anesthesia with propofol can ameliorate remote lung injury induced by intestinal ischemia-reperfusion (IIR). MATERIALS AND METHODS Thirty male Wistar rats were randomly allocated in three groups (n = 10 each): animals in group Sham were anesthetized with ketamine and xylazine and then laparotomy and sham IIR followed. Animals in group IIR received ketamine and xylazine and were then subjected to clamping of the superior mesenteric artery for 45 min and reperfusion for 4 h. Group IIR+P received anesthesia with propofol and then IIR was induced, as in group IIR. Blood samples for blood gases and malondialdehyde measurements were drawn at the end of reperfusion. Bronchoalveolar lavage fluid (BALF) was obtained to measure cell counts, total protein, and phospholipids levels. RESULTS Induction of IIR resulted in deteriorated oxygenation, acidemia, and inflammatory cells sequestration, along with increased BALF protein content and increased proportions of small surfactant aggregates. Anesthesia with propofol alleviated intestinal injury and efficiently prevented lipid oxidation. In group IIR+P inflammatory cell infiltration and pulmonary histologic changes were significantly limited. The increase in BALF total protein and the changes in surfactant aggregates were prevented, leading to normal systemic oxygenation. CONCLUSION Using propofol to induce and maintain anesthesia efficiently prevented IIR-induced lung injury. Systemic antioxidant protection, improvement of intestinal injury, inhibition of the inflammatory response, and preservation of the alveolar-capillary permeability seem to be crucial mediating mechanisms for this simple and clinically relevant intervention.

Acupressure on the Extra 1 Acupoint: The Effect on Bispectral Index, Serum Melatonin, Plasma β-endorphin, and Stress

BACKGROUND: Acupressure on the “extra 1” point decreases bispectral index (BIS) values and stress. METHODS: We investigated the BIS, melatonin, β-endorphin, and verbal stress score values before, after 10 min of acupressure application on the extra 1 point, on a sham point, after no acupressure, and 1 h after completion of each intervention in 12 volunteers. RESULTS: The BIS and verbal stress score values were decreased after acupressure on the extra 1 point (P = 0.0001 and P = 0.008, respectively), but melatonin and β-endorphin did not change. CONCLUSION: Acupressure on the extra 1 point has no effect on melatonin and β-endorphin levels.