Why do orthopedic patients have a higher incidence of serious complications after central neuraxial blockade?
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Humans↗
Biomedical subjects
Axel R Heller
Publications and source records attributed to Axel R Heller.
Perfluorohexane vapor has only minor effects on spatial pulmonary blood flow distribution in isolated rabbit lungs.
We tested the hypothesis that administration of perfluorohexane (PFH) vapor does not significantly affect the relative pulmonary blood flow (Qrel) distribution in isolated rabbit lungs. Fourteen isolated rabbit lungs were perfused with a Krebs-Henseleit buffer solution (flow 150 mL/min). Pulmonary afterload was set to 3 mm Hg. The lungs were ventilated with 4% CO(2) in room air using a small animal ventilator (respiratory rate, 30 breaths/min; tidal volume, 12 mL/kg body weight; positive end-expiratory pressure, 2 cm H(2)O). After a steady-state period, 18 vol. % of PFH vapor was administered to 9 lungs for 30 min. In a second set of experiments five lungs served as controls. Change in (Qrel) distribution was assessed using fluorescent-labeled microspheres. The unpaired Student's t-test was used to compare variables between groups. The paired Student's t-test, the one-sample Student's t-test, the Anderson-Hauck test of equivalence, and Pearson correlation were used to analyze changes within groups. The mean correlation coefficients of (Qrel) were 0.564 +/- 0.182 for the PFH group and 0.502 +/- 0.295 for the control group, respectively. No significant changes in (rel) distribution over time and between groups were found. However, in the PFH group a tendency towards redistribution of (Qrel) to more ventral lung areas was noted. Our results suggest that PFH vapor has no significant effects on redistribution of (Qrel) in isolated rabbit lungs.
Algorithms↗
Omega-3 fatty acids improve liver and pancreas function in postoperative cancer patients.
Epidemiologic studies have indicated that high intake of saturated fat and/or animal fat increases the risk of colon and breast cancer. Omega-3 PUFAs in fish oil (FO) can inhibit the growth of human cancer cells in vitro and in vivo. These effects are related to the uptake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into the cellular substrate pool and their competitive metabolism with arachidonic acid (AA) at the cyclooxygenase and 5-lipoxygenase levels. The metabolites of EPA and DHA have less inflammatory and immunosuppressant potency than the substances derived from AA. Based on previous experimental data, we hypothesized that FO supplementation after major abdominal cancer surgery would improve hepatic and pancreatic function. Ours was a prospective, randomized, double-blinded clinical trial on 44 patients undergoing elective major abdominal surgery, randomly assigned to receive total parenteral nutrition (TPN) supplemented with either soybean oil (SO 1.0 g/kg body weight daily, n = 20) for 5 days or a combination of FO and SO (FO 0.2 + SO 0.8 g/kg body weight daily, n = 24). Compared to pure SO supplementation in the postoperative period, FO significantly reduced ASAT [0.8 +/- 0.1 vs. 0.5 +/- 0.1 mmol/(l. sec)], ALAT [0.9 +/- 0.1 vs. 0.6 +/- 0.1 mmol/(l. sec)], bilirubin (16.1 +/- 5.3 vs. 6.9 +/- 0.6 mmol/l), LDH (7.7 +/- 0.4 vs. 6.7 +/- 0.4 mmol/(l. sec) and lipase (0.6 +/- 0.1 vs. 0.4 +/- 0.1 micromol/(l. sec) in the postoperative course. Moreover, patients with increased risk of sepsis (IL-6/IL-10 ratio >8) showed a tendency to shorter ICU stay (18 hr) under omega-3 PUFA treatment. Weight loss as encountered after the SO emulsion of 1.1 +/- 2.2 kg was absent in the FO group. After major abdominal tumor surgery, FO supplementation improved liver and pancreas function, which might have contributed to the faster recovery of patients.
Aged↗
N(omega)-nitro-L-arginine methyl ester effects on neutrophil function and bacterial clearance.
Nitric oxide synthase (NOS) inhibitors are considered promising as a therapeutic option in severe septic shock. The aim of this study was to investigate the effects of N-nitro-L-arginine methyl ester (L-NAME) application on neutrophil (PMN) respiratory burst, phagocytosis, and elimination of Escherichia coli from blood and tissue in rabbits. Twenty-eight female chinchilla rabbits were randomized to a treatment and control group. To quantify the bacterial clearance process, 10 colony forming units (CFU) of E. coli were injected intravenously into anesthetized rabbits. Animals in the L-NAME group had a significantly higher mortality compared with controls. NOS inhibition resulted in a significant delay of bacterial clearance (P < 0.001). These findings correlated with a significant augmentation of all organ E. coli findings (P = 0.002-0.035). PMN phagocytosis activity was notably reduced by L-NAME treatment during the experimental observation. Neutrophil burst, on the other hand, was amplified by NOS inhibition (P = 0.008). Our findings point to an interference with the PMN-dependent immune mechanisms after L-NAME treatment. The augmented PMN burst reaction could be a compensatory mechanism, potentially leading to tissue damage. Therefore, in this model, we find sufficient evidence pointing to a possible cause for the deleterious effect of early nonselective NOS inhibition in critically ill patients.
Animals↗
Modulation of host defense by hydrocortisone in stress doses during endotoxemia.
OBJECTIVE: To investigate the effects of low-dose hydrocortisone (HC) on neutrophil respiratory burst, phagocytosis, and elimination of E. coli from blood and tissue under endotoxemic and non-endotoxemic conditions. DESIGN. Randomized, controlled trial. SETTING: Experimental laboratory, university hospital. SUBJECTS: Forty-eight female chinchilla rabbits ( n=8 in six groups A-F). INTERVENTIONS: In order to quantify the bacterial clearance process, defined numbers [10(8) colony forming units (CFU)] of Escherichia coli were injected intravenously into all anesthetized rabbits. Group A did not receive further intervention. Group B received bolus administration of HC 1.4 mg/kg and group C 14 mg/kg. Endotoxin (LPS, 40 microg/kg/h) was given to groups D, E, and F. Group E received additional bolus administration of HC 1.4 mg/kg and group F 14 mg/kg. All HC groups (B, C, E, and F) were continuously infused with HC 0.18 mg/kg/h. MEASUREMENTS: Monitored parameters were neutrophil respiratory burst and phagocytosis activity, rates of bacterial elimination from the blood, arterial blood pressure, serum lactate and LPS concentrations, as well as nitrite and nitrate levels. Tissue samples of liver, kidney, spleen, and lung were collected for bacterial counts. MAIN RESULTS: In controls HC significantly delayed elimination of injected E. coli from the blood (P<0.01). LPS also prolonged bacterial elimination but additional HC did not further delay removal of E. coli from the blood. Under endotoxemia HC depressed respiratory burst, whereas phagocytosis functions remained unaltered. Moreover, bacterial colonization of organs was reduced after HC in the LPS groups. Significance, however, was reached only in the liver (P<0.05). Due to HC, clearance from LPS (P<0.01) and lactate (P<0.05) were improved. Levels of nitrite and nitrate did not differ among the groups. CONCLUSION: HC demonstrated immunomodulatory effects even in stress doses. In endotoxemic states use of low-dose HC seems to be favorable, although not in non-septic conditions.
Animals↗
Clusterin protects the lung from leukocyte-induced injury.
Clusterin (CLU) is a multifunctional 75- to 80-kDa glycoprotein that is upregulated during cellular stress and might represent a defense mechanism during local cellular damage. Mechanisms discussed are antiapoptotic, antioxidative, and anticomplement properties as well as chaperone-like features protecting stressed proteins. The aim of this study was to investigate potential protective effects of CLU on pulmonary vasculature after in situ PMN activation in isolated rabbit lungs. The experiments were performed on 24 isolated and ventilated rabbit lungs that were perfused with 200 mL of Krebs-Henseleit-10% blood buffer with a constant flow of 150 mL/min in a recirculating system. It was tested whether pretreatment with CLU (2.5 microg/ml; n = 8) or catalase (CAT, 5000 U/ml; n = 8) before N-formyl-Met-Leu-Phe (fMLP; 10(-8) M) injection influenced pulmonary artery pressure (PAP) peak airway pressures (PAW) and edema formation as compared with controls (n = 8). Baseline values of PAP were 9-11 mmHg and PAW 11-13 cm H2O. Application of fMLP resulted in an acute significant (P < 0.01) increase of PAP (48 +/- 29 mmHg) within 2 min in the control group and PAW increased to 35 +/- 7 cm H2O within 30 min. Pretreatment with CLU completely suppressed the PAP and PAW response as a result of the fMLP challenge (P < 0.001), whereas a transient PAW increase up to 27 +/- 15 mmHg was observed after CAT. Complement factor C3a release was suppressed by CAT, whereas CLU blocked the complement cascade at the level of C5b-9 formation. Moreover, generation of thromboxane A(2) was reduced after CLU and CAT. Lung edema occurred in the fMLP group but was absent (P < 0.001) after CLU and CAT treatment. Both CLU and CAT prevented fMLP-induced lung injury. Stabilizing effects of CLU, point towards complement regulating features at the level of the terminal complement sequence. Elevated levels of CLU during inflammation could reflect a compensatory organ protective mechanism. Further studies are required to elucidate the clinical impact of the observed organ-protective properties of CLU.
Acute-Phase Reaction↗
Fish or chips?
Cell membranes are not simply barriers separating intracellular from extracellular space. Rather, they represent a dynamic high-turnover system that adapts to current demands. During inflammation, prostaglandins and leukotrienes are formed from membrane-derived phospholipids. Encouraging improvements in critically ill patients were observed after nutritional replacement of long-chain omega-6 fatty acids with long-chain omega-3-fatty acids, contained in fish oil.
Animals↗
Misplacement of a psoas compartment catheter in the subarachnoid space.
BACKGROUND AND OBJECTIVES: This case report describes an unusual cause of misplacement of an indwelling catheter in the subarachnoid space after primary psoas compartment block in a patient undergoing total knee arthroplasty. CASE REPORT: A 67-year-old woman presenting for total knee joint replacement received a combination of continuous psoas compartment block and sciatic nerve block. Neurostimulation and additional ultrasound guidance were used for identification of the lumbar plexus. After elicitation of a quadriceps motor response, a negative aspiration test, and an uneventful test dose, 20 mL ropivacaine 0.375% and 20 mL mepivacaine 1% were injected. Despite difficult ultrasound conditions because of intestinal air, local anesthetic spread was observed paravertebrally at the medial border of the psoas muscle as usual. A catheter was then advanced 7 cm through the insulated directional puncture needle. An additional sciatic nerve block was performed by using Labat's approach. Ten minutes after injection unilateral sensory block was noted and surgery was started. After uneventful surgery, bilateral sensory block to the T4 level and complete motor block in both lower limbs was detected. A second aspiration test was negative, and an epidural block was suspected. For verification of the catheter tip location, a computed tomography scan with contrast dye was performed revealing catheter placement in the subarachnoid space. The catheter was removed and showed a kink about 7 cm from the tip. After regression of the neuraxial block, lumbar plexus block persisted for another 2 hours. CONCLUSION: An additional test dose via the catheter is recommended if the indwelling catheter is inserted after injection of the local anesthetics through the puncture needle. If epidural anesthesia occurs, an x-ray of the catheter is advisable because negative aspiration via catheter does not rule out subarachnoid catheter location.
Arthroplasty, Replacement, Knee↗