无创通气不同呼吸界面对COPD患者的生理学影响

目的 探讨无创正压通气(NPPV)时不同呼吸界面对慢性阻塞性肺疾病(COPD)急性加重期并呼吸衰竭患者的生理学影响.方法 选择30例COPD急性加重期并呼吸衰竭患者.无创正压通气时患者随机先后接受不同呼吸界面(面罩、鼻罩和鼻塞).动态观察不同呼吸界面时患者呼吸方式、血气分析和对呼吸界面耐受性等的差异.结果 (1)与自主呼吸相比,无创正压通气时三种不同呼吸界面均可改善患者的潮气量、分钟通气量和呼吸频率(P＜0.01),三种不同呼吸界面时的呼吸频率相似(P＞0.05),但面罩时的潮气量和分钟通气量比鼻罩时更高(P＜0.05);(2)与自主呼吸相比,无创正压通气时三种不同呼吸界面均可改善患者的动脉血气(P＜0.05),面罩和鼻塞时的PCO2比鼻罩时更低(P＜0.05);(3)患者均可耐受三种不同的呼吸界面,但患者对鼻罩的耐受性比面罩和鼻塞更好(P＜0.01).结论 本生理学研究证实了无创正压通气可改善COPD急性加重期并呼吸衰竭患者的呼吸方式和动脉血气,面罩和鼻塞时的疗效更佳,而鼻罩时的耐受性更好.     

Pressure distribution and perceived comfort in casual footwear

The aim of this investigation was to establish the relationship between short-term perceived comfort and pressure distribution on the dorsal and plantar surfaces of the foot, while walking in a range of commercially available casual footwear. The study was carried out in the biomechanics laboratory of Manchester Metropolitan University using 15 male subjects without foot pathology. Perceived upper and plantar comfort were measured using a specially designed questionnaire, while dorsal and plantar pressure distributions were measured using a rectangular sensor pad recording at 30 Hz and a Mikro-EMED insole recording at 100 Hz respectively. Analysis of variance tests were used to determine differences in perceived comfort and pressure distribution between three pairs of shoes. The findings of this study suggest that an increase in total plantar force and force-time integral may relate to a decrease in perceived plantar comfort. For the three shoes examined in this study, overall peak plantar pressure, the pressure-time integral, and total plantar area did not appear to be linked to perceived plantar comfort. Findings for the shoe upper indicate that decreased dorsal forces and pressures may be related to decreased upper comfort. These findings suggest that the measurement of pressure distribution at the foot-shoe interface could be a useful tool in identifying the causes of discomfort in footwear.     

Fluctuating PEEP (F–PEEP) versus conventional PEEP in dogs with asymmetrical lung injury

Fluctuating PEEP (F-PEEP) is a newly developed PEEP in which end-expiratory pressure (EEP) is periodically changed within a certain range. In a dog model with unilateral lung injury induced by the introduction of hydrochloric acid, F-PEEP in which the EEP was periodically changed from 0.5 to 1.5 kPa at periods of 6 min, and conventional PEEP (C-PEEP) with an optimized EEP of 1.0 kPa, were each applied for 30 min. F-PEEP produced a significantly greater improvement of PaO2 and intrapulmonary shunt (QS/QT) than C-PEEP, and at the low EEP phase, the greatest improvement accompanied by an increased dynamic compliance and a large cardiac output was obtained. These results suggest that F-PEEP provides a useful mode of artificial ventilation for the treatment of unilateral lung injury.     

Stimulation of locus coeruleus increases arterial pressure in rabbits

目的：研究电刺激和化学刺激兔蓝斑（ＬＣ）对动脉血压（ＡＰ）和肾交感神经传出活动（ＲＳＡ）的影响．方法：电刺激ＬＣ，ＬＣ微量注射ＬＧｌｕ、盐酸吗啡、ＧＡＢＡ、电解毁损ＬＣ，记录ＡＰ和ＲＳＡ．结果：电刺激ＬＣ和ＬＣ注射ＬＧｌｕ均引起ＡＰ升高（分别为１３５±０３ｖｓ１９５±０８ｋＰａ和１３８±０４ｖｓ１７５±０８ｋＰａ）和ＲＳＡ增加．ＬＣ注射吗啡、ＧＡＢＡ对ＡＰ和ＲＳＡ无明显影响．电解毁损ＬＣ后电刺激ＬＣ区、ＬＣ区注射ＬＧｌｕ对ＡＰ和ＲＳＡ无明显影响．结论：兔ＬＣ兴奋引起ＡＰ升高和ＲＳＡ增加，但ＬＣ不是ＡＰ和ＲＳＡ的紧张性中枢．     

红霉素对犬幽门括约肌压力影响及其与胃动素,生长抑素的关系

为探讨红霉素对犬幽门括约肌的作用及其机理，及其与血浆胃动素，生长抑素的关系。方法采用胃压力测量仪及放射免疫法，同步监测观察了１０条犬静脉滴ＥＭ前后和使用拮抗剂后的幽门压力、血浆ＭＴＬ，ＳＳ的变化，结论：ＥＭ具有增高犬胃幽门压力的作用，其作用机理除与血浆ＭＴＬ有着密切的关系外，血浆ＳＳ也可能共同参与了其调节机制。     

血压在前阻力血管中下降最快的原因分析

目的：解释血压在毛细血管前阻力血管中下降最快的原因。方法：利用物理模型简化复杂的心血管系统。结果：全身所有的微、小动脉段“并联”，全身所有的毛细血管段“并联”。结论：微、小动脉段的总流阻最大、使俐血压在微、小动脉中下降最快。     

带血管蒂舟骨瓣移位术的应用解剖

目的:为治疗距骨骨折提供新术式的解剖学基础.方法:在30侧灌注红色乳胶的成人下肢标本上,对舟骨背侧面形态、血供来源进行观测.结果:舟骨背侧面动脉主要来自内踝前动脉、跗内侧动脉以及足底内侧动脉浅支,分别发3～5支、1～3支和1～2支外径在0.2～1.0mm之间的骨膜支,形成骨膜动脉网.结论:以内踝前血管为蒂,可切取舟骨背侧2.0cm×1.0cm×0.5cm大小的骨瓣,用于距骨颈骨折修复.术式经临床应用证实,手术简便,效果可靠.     

EFFECT OF CROSS-FOSTERING ON NEONATAL SODIUM BALANCE AND ADULT BLOOD PRESSURE IN THE SPONTANEOUSLY HYPERTENSIVE RAT

1. The aim of the present study was to compare electrolyte handling in naturally reared neonatal spontaneously hypertensive rats (SHR) with those reared by a Wistar-Kyoto (WKY) rat foster mother (denoted SHRX), as cross-fostering SHR pups to a WKY rat dam lowers adult blood pressure in the SHR. 2. The electrolyte content of WKY rat and SHR dams’ milk was determined and electrolyte intake and urinary excretion rates were calculated in both naturally reared and cross-fostered WKY rat and SHR pups. 3. The milk sodium concentration fell in both strains (WKY rat: 31.8 ± 2.0 to 15.2 ± 1.2 mmol/L; SHR 31.9 ± 2.5 to 18.2 ± 1.6 mmol/L; P < 0.001), as did potassium (P < 0.001), over lactation, but there were no differences between strains. Calcium and magnesium concentrations increased (P< 0.001), although SHR dam's milk contained less calcium (P < 0.001) than that of WKY rat dams during the third week of lactation. 4. Spontaneously hypertensive rat pups ingested less milk (P<0.05) than WKY rat pups; therefore, their cumulative sodium intake over postnatal days 4–15 was significantly lower than that of WKY rat pups (WKY rat vs SHR: 84.4 ± 3.6 vs 59.7 ± 2.6 μmol/g bodyweight, respectively; P < 0.05) and fostered SHRX pups (77.7 ± 7.0 μmol/g bodyweight; P < 0.05). Potassium and magnesium intakes were comparable between SHR, WKY rat and SHRX pups, but SHR pups ingested significantly less calcium than either WKY rat pups (136.1 ± 6.4 vs 200.1 ± 9.5p, mol/g bodyweight, respectively; P<0.05) or SHRX pups (200.0 ± 18.0 μmol/g bodyweight; P<0.05). 5. These data show that the neonatal SHR experiences a period of sodium deficiency during the developmental stage when cross-fostering is effective in lowering blood pressure. This is consistent with the reported up-regulation of the renin-angiotensin system observed in SHR at this time and may have a long-term influence on blood pressure.     

THE EFFECT OF HYPERTENSIVE EPISODES AND CARDIAC HYPERTROPHY ON THE CANINE CARDIAC BAROREFLEX

1. Left ventricular (LV) hypertrophy has been implicated in the reduction of baroreflex sensitivity present in hypertension. The aim of the current study was to investigate the mean arterial pressure-heart rate reflex (MAP-HR) in a model which induced left ventricular hypertrophy but no sustained blood pressure elevation. 2. Five mongrel dogs were exposed to transient blood pressure elevation of between 20 and 30 mmHg, through hindlimb compression using a pneumatic pressure suit, for 7 h per day, 6 days per week for 6 weeks. Resting blood pressure was not altered by the 6 week hindlimb compression intervention. 3. Echocardiographically determined LV mass (mean ± s.e.m.) was 116.0 ± 7.4 g prior to hindlimb compression (baseline) and elevated to 125.4 ± 8.1 g (P= 0.003) after 6 weeks of compression. A reduction in the early (E) to late (A) transmitral diastolic flow ratio (E/A) from 1.80 ± 0.06 at baseline to 1.54 ± 0.09 (P = 0.037) after the 6 week intervention suggested that cardiac compliance was reduced. 4. The maximum gain of the MAP-HR reflex, studied using the ‘steady-state’ drug technique, when blood pressure was normal, showed a trend for reduction from 3.85 ± 0.43 beats/min per mmHg at baseline to 3.10 ± 0.45 beats/min per mmHg (P= 0.067) after 6 weeks of compression. This gain reduction became significant after β-adrenoceptor blockade with propranolol (3.13 ± 0.55 vs 2.32 ± 0.25 beats/min per mmHg; P= 0.039). Covariant analysis showed a significant inverse correlation between LV mass and maximum gain (r= 0.96; P<0.001) during the 6 week compression period. 5. The MAP-HR reflex changes in this model mimic those present in hypertension and implicate cardiac hypertrophy as one possible mediator.