Apostolos Papalois

Real-time ultrasound-guided subclavian vein cannulation versus the landmark method in critical care patients: A prospective randomized study*

Objective:Subclavian vein catheterization may cause various complications. We compared the real-time ultrasound-guided subclavian vein cannulation vs. the landmark method in critical care patients. Design:Prospective randomized study. Setting:Medical intensive care unit of a tertiary medical center. Patients:Four hundred sixty-three mechanically ventilated patients enrolled in a randomized controlled ISRCTN-registered trial (ISRCTN-61258470). Interventions:We compared the ultrasound-guided subclavian vein cannulation (200 patients) vs. the landmark method (201 patients) using an infraclavicular needle insertion point in all cases. Catheterization was performed under nonemergency conditions in the intensive care unit. Randomization was performed by means of a computer-generated random-numbers table and patients were stratified with regard to age, gender, and body mass index. Measurements and Main Results:No significant differences in the presence of risk factors for difficult cannulation between the two groups of patients were recorded. Subclavian vein cannulation was achieved in 100% of patients in the ultrasound group as compared with 87.5% in the landmark one (p < .05). Average access time and number of attempts were significantly reduced in the ultrasound group of patients compared with the landmark group (p < .05). In the landmark group, artery puncture and hematoma occurred in 5.4% of patients, respectively, hemothorax in 4.4%, pneumothorax in 4.9%, brachial plexus injury in 2.9%, phrenic nerve injury in 1.5%, and cardiac tamponade in 0.5%, which were all increased compared with the ultrasound group (p < .05). Catheter misplacements did not differ between groups. In this study, the real-time ultrasound method was rated on a semiquantitative scale as technically difficult by the participating physicians. Conclusions:The present data suggested that ultrasound-guided cannulation of the subclavian vein in critical care patients is superior to the landmark method and should be the method of choice in these patients.

Comparison of Monopolar Electrocoagulation, Bipolar Electrocoagulation, Ultracision, and Ligasure

PurposeHemostasis is a fundamental principle of surgery. We compared the safety and efficacy of monopolar electrocoagulation (ME), bipolar electrocoagulation (BE), Ligasure (LS), a modern bipolar vessel sealing system, and Ultracision (UC), a system of ultrasound energy based shears. We also studied the healing process after their use.MethodsWe used each of the above methods to coagulate and divide the short gastric vessels of 16 white male New Zealand rabbits. The animals were killed after 3, 7, 14, or 21 days, and the coagulation sites and the adjacent gastric wall were examined histologically.ResultsLS and UC achieved complete hemostasis without any complications. Conversely, ME and BE often resulted in failed coagulation and perforation of the neighboring gastric wall from a side thermal injury. Histologically, LS demonstrated the mildest side thermal injury and the fastest healing process. We noted greater thermal injury and inflammatory response after UC than after LS on days 7 and 14; however, ME and BE caused the most severe lesions.ConclusionsLS and UC are clearly the safest and most efficient methods of coagulation, whereas ME and BE could cause serious clinical and histological complications. We found histological evidence that UC causes a slightly greater inflammatory response than LS, and the clinical implications of this warrant further investigation.

Sedation in gastrointestinal endoscopy: Current issues

Diagnostic and therapeutic endoscopy can successfully be performed by applying moderate (conscious) sedation. Moderate sedation, using midazolam and an opioid, is the standard method of sedation, although propofol is increasingly being used in many countries because the satisfaction of endoscopists with propofol sedation is greater compared with their satisfaction with conventional sedation. Moreover, the use of propofol is currently preferred for the endoscopic sedation of patients with advanced liver disease due to its short biologic half-life and, consequently, its low risk of inducing hepatic encephalopathy. In the future, propofol could become the preferred sedation agent, especially for routine colonoscopy. Midazolam is the benzodiazepine of choice because of its shorter duration of action and better pharmacokinetic profile compared with diazepam. Among opioids, pethidine and fentanyl are the most popular. A number of other substances have been tested in several clinical trials with promising results. Among them, newer opioids, such as remifentanil, enable a faster recovery. The controversy regarding the administration of sedation by an endoscopist or an experienced nurse, as well as the optimal staffing of endoscopy units, continues to be a matter of discussion. Safe sedation in special clinical circumstances, such as in the cases of obese, pregnant, and elderly individuals, as well as patients with chronic lung, renal or liver disease, requires modification of the dose of the drugs used for sedation. In the great majority of patients, sedation under the supervision of a properly trained endoscopist remains the standard practice worldwide. In this review, an overview of the current knowledge concerning sedation during digestive endoscopy will be provided based on the data in the current literature.

IGF-1 Expression in Infarcted Myocardium and MGF E Peptide Actions in Rat Cardiomyocytes in Vitro

Insulinlike growth factor-1 (IGF-1) expression is implicated in myocardial pathophysiology, and two IGF-1 mRNA splice variants have been detected in rodents, IGF-1Ea and mechano-growth factor (MGF). We investigated the expression pattern of IGF-1 gene transcripts in rat myocardium from 1 h up to 8 wks after myocardial infarction induced by left anterior descending coronary artery ligation. In addition, we characterized IGF-1 and MGF E peptide action and their respective signaling in H9C2 myocardial-like cells in vitro. IGF-1Ea and MGF expression were significantly increased, both at transcriptional and translational levels, during the late postinfarction period (4 and 8 wks) in infarcted rat myocardium. Measurements of serum IGF-1 levels in infarcted rats were initially decreased (24 h up to 1 wk) but remained unaltered throughout the late experimental phase (4 to 8 wks) compared with sham-operated rats. Furthermore, specific anti-IGF-1R neutralizing antibody failed to block the synthetic MGF E peptide action, whereas it completely blocked IGF-1 action on the proliferation of H9C2 cells. Moreover, this synthetic MGF E peptide did not activate Akt phosphorylation, whereas it activated ERK1/2 in H9C2 rat myocardial cells. These data support the role of IGF-1 expression in the myocardial repair process and suggest that synthetic MGF E peptide actions may be mediated via an IGF-1R independent pathway in rat myocardial cells, as suggested by our in vitro experiments.

Short-term statin administration in hypercholesterolaemic rabbits resistant to postconditioning: effects on infarct size, endothelial nitric oxide synthase, and nitro-oxidative stress

AIMS The effectiveness of postconditioning (POC) in hypercholesterolaemia is in dispute. We investigated the effects of 3-day lipophilc (simvastatin) or hydrophilic (pravastatin) statin treatment, without or with POC in normocholesterolaemic (Norm) and hypercholesterolaemic (Chol) rabbits. METHODS AND RESULTS Norm or Chol rabbits were subjected to 30 min ischaemia and randomized in two series of 12 groups each: control, simvastatin (Sim), pravastatin (Prav), POC, Sim-POC, Prav-POC, Chol, Sim-Chol, Prav-Chol, POC-Chol, Sim-POC-Chol, Prav-POC-Chol. After ischaemia, rabbits of the first series underwent 3 h reperfusion, followed by infarct size, total cholesterol, and low density lipoprotein plasma level evaluation; animals of the second series underwent 10 min reperfusion followed by tissue sampling for nitrotyrosine (NT), malondialdehyde, endothelial nitric oxide synthase (eNOS), and Akt analyses. N-nitro-l-arginine methylester (L-NAME) was given in two additional groups (POC-L-NAME and Prav-Chol-L-NAME) for infarct size assessment. All interventions reduced infarction in Norm (24.3 ± 1.3, 25.9 ± 2.8, 27.9 ± 3.1, 23.3 ± 2.3, and 33.4 ± 2.5%, in POC, Sim, Prav, Sim-POC, and Prav-POC groups, respectively, vs. 49.3 ± 1.9% in control, P < 0.05), but only Prav did so in Chol animals (25.7 ± 3.3 and 25.3 ± 3.9% in Prav-Chol and Prav-POC-Chol vs. 50.9 ± 1.7, 44.8 ± 4.3, 41.5 ± 3.5, and 49.3 ± 5.5% in Chol, Sim-Chol, POC-Chol, and Sim-POC-Chol, respectively, P < 0.05). L-NAME abolished the infarct size-limiting effect of POC and Prav-Chol. Prav induced the greatest reduction in NT, while it was the only intervention that increased myocardial eNOS and Akt in Chol rabbits (P < 0.05 vs. all others). CONCLUSION Prav, in contrast to same-dose Sim or POC, reduces infarction in Chol rabbits independently of lipid lowering, potentially through eNOS activation and nitro-oxidative stress attenuation.

Preconditioning limits myocardial infarct size in hypercholesterolemic rabbits.

BACKGROUND Hypercholesterolemia predisposes to coronary artery disease and causes endothelial dysfunction; some reports suggest that endothelial derived substances are involved in ischemic preconditioning. OBJECTIVE Our aim was to examine the possibility that preconditioning maybe attenuated in a clinically relevant animal model of hypercholesterolemia with atherosclerosis. METHODS Male rabbits were fed with cholesterol enriched diet and then divided into two groups (A and B) without and with preconditioning, respectively. A second series of rabbits fed a normal diet were similarly divided into two groups (C and D) without and with preconditioning, respectively. All the animals were subjected to 30 min ischemia and 180 min reperfusion. Blood samples were collected for cholesterol assessment; arterial and heart samples were harvested at the end for histopathological examination. Infarct (I) and risk areas (R) were delineated with Zn-Cd particles and TTC staining. RESULTS Cholesterol in groups A and B was 58.3+/-8.7 mg% at baseline and 1402+/-125 mg% at 8 weeks (P<0.0001) and in groups C and D 57.5+/-5.8 mg% before the surgical procedure. I/R% was 39. 3+/-6.3% in group A, 16.7+/-3.9% in B (P<0.01), 41.4+/-7.5% in C and 10.8+/-3.3% in D (P<0.01). CONCLUSION We conclude that preconditioning is unlikely to be attenuated by hypercholesterolemia.

Catheter-based renal sympathetic denervation exerts acute and chronic effects on renal hemodynamics in swine

OBJECTIVES We investigated the acute and chronic effects of catheter-based renal sympathetic denervation (RSD) on renal hemodynamics assessed by average peak velocity (APV), renal blood flow (RBF), renal flow reserve (RFR) and resistive index (RI). BACKGROUND Sympathetic overdrive is accompanied by impaired RBF, whereas there is no data on the effects of transcatheter RSD on renal hemodynamic balance. METHODS Before and post-RSD (acutely and after 1 month), in 9 farm swines we measured APV by a 0.014-inch Doppler flow wire placed in the stem of the renal artery under baseline and hyperemic conditions, induced by intrarenal dopamine (50 μg/kg). RFR was calculated as the ratio of hyperemic to basal peak velocity, and RI was estimated as (peak systolic velocity-end-diastolic velocity)/peak systolic velocity. RSD was achieved via the lumen of the main renal artery with a specifically designed catheter connected to a radiofrequency generator according to prespecified algorithm. RESULTS APV and RBF increased acutely post ablation in all animals, compared to APV and RBF before ablation (61.44 ± 32.6 vs 20.44 ± 6.38 cm/s, p<0.001 and 407.4 ± 335.1 vs 161.1 ± 76.6 ml/min, p=0.003; respectively), whereas RFR and RI were reduced (1.51 ± 0.59 vs 2.85 ± 1.33, p<0.001 and 0.67 ± 0.07 vs 0.74 ± 0.07, p=0.005; respectively). One month post ablation APV and RBF compared to APV and RBF before ablation remained significantly higher whereas RFR and RI remained lower as compared to baseline. CONCLUSIONS Catheter-based RSD exerts acute and chronic effects on renal hemodynamics in a large animal model. If confirmed in humans RBF parameters may be used as direct markers of successful RSD.

Reduction of myocardial infarct size in rabbits by a novel indole derivative with antioxidant and free radical scavenging properties.

We investigated the cardioprotective efficacy of a new compound, 3-[(1H-1-indolyl)methyl] -4-amino 4,5-dihydro-1H,1,2,4 triazole-5-thione (C6458). The effect of C6458 on the reduction of the infarct size and its protective ability against oxidative damage of the myocardium after ischemia-reperfusion was examined in rabbits that were subjected to 30 min regional ischemia and 2 h reperfusion. C6458 was administered by continuous infusion for 30 min starting at the 10th minute of sustained ischemia and ending at the 10th minute of reperfusion (two doses, 100 and 200 micromol/kg BW). Infarct and risk areas were delineated with Zn2+-Cd2+ particles and triphenyl tetrazolium chloride staining. Antioxidant activity was detected spectrophotometrically by the measurement of malondialdehyde formation. C6458 reduced significantly the level of malondialdehyde in rabbits under ischemia-reperfusion at both doses. Interestingly, at the dose of 200 micromol/kg, the compound decreased the malondialdehyde levels from the 1st minute of reperfusion and significantly reduced infarct size. The free radical scavenging properties of the compound were examined in vitro by determination of the interaction with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical. The ability of the C6458 to scavenge HO* was established by its competition with dimethyl sulfoxide (DMSO) for HO radicals. The compound tested showed a significant effect in the above assays. We conclude that C6458 possesses a protective effect against both damaged myocardium and infarct size in anesthetized rabbits. This beneficial effect may be attributed, at least in part, to its antioxidant and free radical scavenging activity.

Protective effect of a novel antioxidant non-steroidal anti-inflammatory agent (compound IA) on intestinal viability after acute mesenteric ischemia and reperfusion

Reactive oxygen species play an important role in the basic pathophysiology of ischemia-reperfusion injury. We investigated whether the administration of a novel non-steroidal anti-inflammatory compound with antioxidant properties, the compound [5-(2-amino-ethylamino)-1-phenyl-2-pentanone] (compound IA), has a beneficial effect on the repair process of the intestinal mucosa after transient mesenteric ischemia in a randomized blind trial. Six groups of rats were subjected to a model of 60 min of intestinal ischemia that was produced by occluding the superior mesenteric artery. At the end of ischemia, compound IA was administered intravenously and the clamp was removed allowing reperfusion. At 60 min after reperfusion, animals were sacrificed and a 10 cm section of terminal ileum was resected. The outcome was evaluated by histopathologic assessment, measurement of polymorphonuclear leukocytes and the extent of lipid peroxidation measuring the small intestine tissue malondialdehyde. After 1 h of reperfusion, the mucosal damage was less in IA-treated rats compared with the control group. Moreover, the number of polymorphonuclear leukocytes in intestinal mucosa was significantly lower in IA group. Compound IA resulted in a statistically significant reduction of the concentration of small intestine tissue malondialdehyde, compared to those of controls. Administration of compound IA decreased the mucosal damage in rats that were subjected to 60 min of ischemia followed by 60 min of reperfusion. The mechanism of compound IA action is considered to be mediated via its potent antioxidant, free radical scavenging activities and inhibition of polymorphonuclear leukocytes infiltration.

The Effects of Vasopressors on Perfusion of Gastric Graft after Esophagectomy. An Experimental Study

AimsTo evaluate the impact of the perioperative administration of norepinephrine on the perfusion of the esophageal graft.MethodsThis is an experimental study. Six swine underwent transhiatal esophagectomy; the stomach was used to replace the resected esophagus. We provoked hemorrhagic shock to the animals and then we administered noradrenaline to restore the blood pressure. We monitored the graft perfusion perioperatively using the technique of microdialysis.ResultsIn all animals, the graft experienced severe hypoperfusion after the administration of noradrenaline that was statistically significant.ConclusionsOur data support the hypothesis that norepinephrine should be used with extreme caution in the perioperative setting after esophagectomy. Further studies, however, will be required to evaluate the clinical significance of this finding.