Favorable effects of epidural analgesia on hemodynamics,oxygenation and metabolic variables in the immediate post-anesthetic period

Fourteen adult patients undergoing elective major abdominal surgery were divided into two groups. One group received epidural and general anesthesia (epidural group), and 20 ml of 0.125% bupivacaine and 2 mg of morphine were administered epidurally about 30 min before the end of the operation for post-anesthetic analgesia. The other group (control group) received general anesthesia alone with nitrous oxide, oxygen and enfiurane. Flow-directed pulmonary arterial and radial arterial catheters were inserted preoperatively, and hemodynamic, respiratory, neuroendocrine and metabolic variables were measured serially. The data were compared during anesthesia and the immediate post-anesthetic recovery period. In the control group, the plasma epinephrine level in the post-anesthetic recovery period increased about four times over the anesthetic period. Oxygen consumption was increased and mixed venous oxygen saturation was decreased significantly. There was a close linear correlation between oxygen consumption (Y) and plasma epinephrine (X) level: Y = 285.7X + 90.5 (P < 0.01, r = 0.72). On the other hand, plasma epinephrine, oxygen consumption and mixed venous oxygen saturation did not change significantly in the epidural group in the post-anesthetic recovery period. There was also a close linear correlation between oxygen consumption (Y) and oxygen delivery (X): Y = 0.22X -32.0 (P < 0.01, r = 0.89). We conclude that the surgical stress and anesthetic reversal may seriously influence neuroendocrine responses and subsequently increase plasma epinephrine. Tissue oxygenation and metabolic imbalance may occur due to the rapid increase of epinephrine in the postanesthetic recovery period. Epidural analgesia at this period may play a more important role and have a more favorable effect on the tissue metabolism.     

Monitoring of central venous oxygen saturation versus mixed venous oxygen saturation in critically ill patients

Continous monitoring of mixed venous (SvO₂) and central venous (ScO₂) oxygen saturation was compared in 7 critically-ill patients (Apache II score: 19±2.1) to determine whether or not information derived from ScO₂ were reliable in clinical practice. Patients were catheterized with both a pulmonary artery (PA) and a central venous (CV) catheter, each of them mounted with fiberoptic sensors (Opticath PA Catheter P7110 and Opticath CV Catheter U440, Abbott). A total of 580 comparative measurements were obtained during periods without and with therapeutic interventions (drug-titration, bronchial suction, use of PEEP, changes in FiO₂...). The systematic error between the 2 measurement techniques was 0.6% and 0.3% in periods with and without therapeutic interventions, respectively. The variability between the 2 techniques was 10% for both periods. Differences between the values were 5% in 49% of values during periods of stability and in 50% of values during periods with therapeutic interventions. There were poor correlations between the values during periods without (r=0.48) and with therapeutic interventions (r=0.62). Better, but still less than ideal, correlations were obtained with changes in SvO₂ and ScO₂ during periods without (r=0.70) and with therapeutic interventions (r=0.77). Although there is a need to develop a simple technique to monitor mixed venous oxygen saturation, the present study indicates that ScO₂ monitoring was not reliable in the study patients.     

Effect of halothane and enflurane on hepatic blood flow and oxygen consumption in dogs

We investigated the relative effects of 0.5, 1.0, 1.5, 2.0 MAC halothane and enflurane, and concurrent noxious stimulus on hepatic blood flow and oxygen consumption in 14 mongrel dogs randomly divided into groups of seven each. Hepatic arterial and portal venous blood flow (HABF and PVBF, respectively) were measured continuously using ultrasonic transit time flow meter. Mean arterial blood pressure (MAP), cardiac index (CI), hepatic oxygen supply, and hepatic oxygen consumption (H _{O 2}) were measured. Halothane significantly deceased HABF, but not PVBF in a dose dependent manner. Enflurane did not affect HABF and PVBF significantly. MAP and CI decreased in both groups, with halothane producing more marked decreases than enflurane. H _{O 2} did not change with enflurane, but did with halothane, producing significant differences, with halothane being greater at 1.5, 2.0 MAC. A noxious stimulus only caused minor change in blood flow. The results suggest that liver blood flow and oxygen consumption are affected differently by halothane and enflurane and that halothane has a stronger tendency to cause an imbalance between liver oxygen supply and consumption than dose enflurane.(Masaki E, Yasuda N, Tanifuji Y et al.: Effect of halothane and enflurane on hepatic blood flow and oxygen consumption in dogs. J Anesth 3: 118–122, 1989)     

Modulation of Macrophage Activity by Proteolytic Enzymes. Differential Regulation of IL-6 and Reactive Oxygen Intermediates (ROIs) Synthesis as a Possible Homeostatic Mechanism in the Control of Inflammation

Inflammatory foci are rich in proteases released by neutrophils (serine proteases) and macrophages (metalloproteases). These enzymes can degrade extracellular matrix proteins and cell membrane bound proteins thus contributing to the development and progression of inflammatory reaction. In this study we have investigated the influence of collagenase (metalloprotease) and trypsin (serine protease) on murine resident and oil-induced peritoneal macrophages (Mf). Short in vitro treatment of Mf, not affecting cell viability, significantly reduced the release of reactive oxygen intermediates (ROIs) and at the same time triggered the increase of IL-6 production and to lesser extent of TNF-alpha production. Both these effects were dependent on enzyme concentration used and were particularly well pronounced in resident macrophages. In addition both enzymes cleaved a number of cell-membrane molecules, including CD23, CD14, CD95L, and Mac-3. We hypothesize that the enzymatic digestion of certain Mf surface receptor proteins in inflammatory foci may be responsible for modification of cell behaviour either by preventing the generation of specific signal or alternatively by delivering a mock substitute signal to the cell interior. In effect inhibition of ROIs production limits their destructive effects and the increase in the secretion of IL-6 stimulates the synthesis of acute phase proteins and triggers other anti-inflammatory mechanisms thus directing Mf present in inflammatory foci into regulatory pathway rather than allowing them to perform solely the effector function.     

Gas-to-liquid permeation in silicon-containing, crosslinked, glassy copotymers of methyl methacrylate

Copolymers of methyl methacrylate with disiloxane derivatives have been proposed as biomaterials for contact lens applications. Although glassy, these copolymers exhibit high oxygen permeability and adequate wettability so that they can be used for manufacture of hard, extended wear lenses. CrossHnked copolymers of poly(methyl methacrylate-co-1,3-bis(methacryloxymethyl)-1,1,3,3-tetramethyl-disiloxane), P(MMA-co-BMTDS), containing from 0.085 to 0.53 mole fraction of BMTDS were prepared and tested for oxygen permeation using a novel apparatus which simulates the atmosphere/lens/cornea conditions. The gas-to-liquid dissolved oxygen permeability, P_gd, was determined and it was found to increase with BMTDS content Permeability values for P(MMA-co-BMTDS) at 34°C were significantly higher than for pure homopolymer PMMA, although these copolymers were glassy at this temperature. The increased oxygen permeation was attributed to increased oxygen solubility in the copolymers due to the presence of the -Si-0-bonds.     

Role of nitric oxide in skeletal muscle: synthesis,distribution and functional importance

Over the last two decades, nitric oxide (NO) has been established as a novel mediator of biological processes, ranging from vascular control to long-term memory, from tissue inflammation to penile erection. This paper reviews recent research which shows that NO and its derivatives also are synthesized within skeletal muscle and that NO derivatives influence various aspects of muscle function. Individual muscle fibres express one or both of the constitutive NO synthase (NOS) isoforms. Type I (neuronal) NOS is localized to the sarcolemma of fast fibres; type III (endothelial) NOS is associated with mitochondria. Isolated skeletal muscle produces NO at low rates under resting conditions and at higher rates during repetitive contraction. NO appears to mediate cell–cell interactions in muscle, including vasodilation and inhibition of leucocyte adhesion. NO also acts directly on muscle fibres to alter cell function. Muscle metabolism appears to be NO-sensitive at several sites, including glucose uptake, glycolysis, mitochondrial oxygen consumption and creatine kinase activity. NO also modulates muscle contraction, inhibiting force output by altering excitation–contraction coupling. The mechanisms of NO action are likely to include direct effects on redox-sensitive regulatory proteins, interaction with endogenous reactive oxygen species, and activation of second messengers such as cyclic guanosine monophosphate (cGMP). In conclusion, research published over the past few years makes it clear that skeletal muscle produces NO and that endogenous NO modulates muscle function. Much remains to be learned, however, about the physiological importance of NO actions and about their underlying mechanisms.     

Liminal therapy: A strategy for the complete and selective destruction of malignant tissue

The property of aerobic glycolysis commonly possessed by malignant cells points to a weakness in oxidative metabolism which has been equated in some tumours with partial uncoupling of oxidative phosphorylation. The suggestions are made, first, that this endogenous defect may account for spontaneous cell death , and, second, that its accentuation would inflict extensive tumour injury upon sensitive neoplasms. Certain drugs not in current use for the treatment of malignant disease are known to be able to interfere selectively with energy metabolism in sensitive tumours to such an extent that widespread necrotisation ensues. The drugs activate an endogenous destructive mechanism that appears to require oxygen. Liminal therapy, the maintenance of continuous destructive pressure on sensitive growths in such a manner that maximal anti-tumour activity in terms of interference with energy production is not achieved at any one time, and under conditions in which the oxygen supply is only partly depleted, is put forward as a possible means of achieving complete and selective tumour destruction .     

高压氧对人重症牙周炎牙龈血流量、血流速度和血浓度作用及机理研究

目的 :探讨高压氧 (HBO)对人重症牙周炎牙龈血流量 (GBF)、血流速度 (BCV)和血浓度 (BC)的作用及HBO治疗牙周炎的机理。方法 :选自口腔中心门诊的 3 0例重症牙周炎患者 ,随机分为二组 ,即治疗组和对照组 ,治疗组用HBO治疗 ,对照组用漱口液漱口。用激光多普勒血流仪测定二组治疗前后的GBF、BCV和BC。结果 :HBO能使牙周炎患者GBF增加 2 .1倍 ,BCV增加 6.7倍 ,BC降低为治疗前的 5 8.2 % ,与对照组比均有非常显著性差异 (P <0 .0 1)。结论 :HBO能使牙周炎患者GBF和BCV增加 ,BC减少 ,能改善牙龈微循环 ,对治疗牙周炎有积极意义     

基于MSP430F149的血氧饱和度检测仪

本文根据红光和红外光透过手指动脉血管后的相对最大光强和光强的最大变化量之比来计算血氧饱和度的一般原理推导出实用的计算方法,并结合MSP430F149微处理器低功耗优势,以及丰富的外围资源研制设计的可控增益放大器等,有效地克服了由于个人生理差异而引起的测量信号基线漂移,满足了仪器便携化设计的需求.     

Protective role of superoxide dismutase in human sperm motility: superoxide dismutase activity and lipid peroxide in human seminal plasma and spermatozoa.

The levels of superoxide dismutase (SOD), a highly specific scavenging enzyme for superoxide anion radicals (O2-), and lipid peroxide produced by oxygen free radicals were measured in human seminal plasma and spermatozoa. Seminal plasma contained 366.8 +/- 20.9 U/ml (mean +/- SE) of SOD activity. SOD activity in human spermatozoa showed a significant correlation to the number of motile spermatozoa, while the activity in seminal plasma did not relate to the sperm concentration or motility. The lipid peroxide concentration in seminal plasma was 6.22 +/- 0.46 nmol/ml and had no significant relationship to sperm concentration or motility. The malondialdehyde (MDA) concentration in spermatozoa was significantly related to the number of immotile spermatozoa. A decrease in the motility of spermatozoa incubated in medium without seminal plasma was observed after 120 min, while the MDA concentration of the spermatozoa increased. Addition of exogenous SOD (400 U/ml) to the sperm suspension significantly decreased this loss of motility and the increase of the MDA concentration. These data suggest a significant role for SOD in sperm motility. It seems that lipid peroxidation of human spermatozoa may cause loss of motility and that SOD may inhibit this lipid peroxidation. These results suggest that SOD may have a possible clinical application in the use of spermatozoa for in-vitro fertilization (IVF) or artificial insemination.