Acute saline infusion induces extracellular acidification and activation of the Na+/H+ exchanger in man

The effect of acute expansion of the extracellular fluid volume (ECV) with isotonic (0.9%) saline on the activity of the lymphocyte Na⁺/H⁺ antiport (NHE) was studied in a total of 18 healthy volunteers. Saline was infused at a constant rate so that 4 mmol kg^?1 b.w. was administered over 2 h. NHE activity was measured by quantifying cytosolic pH (pH_i) recovery following acidification of the cells with propionic acid and by pH clamping at various pH_i values between 7.2 and 5.8 using nigericin. Both methods demonstrate NHE activation associated with intravenous saline infusion, the kinetic difference being a marked decrease in the Hill coefficient n from 3.28 ± 0.21 (SEM) to 2.22 ± 0.11 in the absence of changes in baseline pH_i (7.14 ± 0.02 vs. 7.08 ± 0.02; P = 0.15), V_max (42.8 ± 2.7 vs. 48.1 ± 2.8 mmol L^?1 min^?1; P = 0.08) and pK (6.32 ± 0.04 vs. 6.35 ± 0.02). NHE activation was associated with significant decreases in serum chloride (P = 0.016), calcium (P = 0.008), total cholesterol (P = 0.008), low-density lipoproteins (P = 0.016) and high-density lipoproteins (P = 0.008). Moreover, saline infusion induced extracellular acidification with a decrease in pH from 7.39 ± 0.01 to 7.37 ± 0.01 (P = 0.016), HCO₃^? from 23.3 ± 0.43 mmol L^?1 to 21.3 ± 0.25 mmol L^?1 (P = 0.008) and base excess from ?1.03 ± 0.38 mmol L^?1 to ?3.00 ± 0.31 mmol L^?1 (P = 0.008). Our results show for the first time that acute ECV expansion with isotonic saline is followed by an activation of the lymphocyte NHE. The underlying mechanism(s) remain to be investigated. However, the demonstration in our study of marked changes in acid–base balance induced by acute saline points to a possible inter-relationship of antiporter activation and extracellular acidification.     

Model for the physics and physiology of fluid administration

This article describes a model designed to provide an understanding of fluid flow in intravenous systems and human subjects. Experiments were developed which demonstrate that the model can represent common clinical situations. The model depicts physical devices as ideal resistors, pressure sources, and flow sources. The patient's venous system is depicted as a combination of ordinary and Starling resistors. For flows between 0 and 300 ml/hr, both physical devices and patients are adequately represented by a straight line representing the pressure-flow relationship (PFR): pressure = opening pressure + flow × resistance, where the slope is the resistance to fluid flow and the intercept is the opening pressure. The PFR for a normal vein is characterized by a flat slope (vein resistance =22±20 mm Hg/L/hr, mean ± SD) and a low intercept (opening pressure =15±8 mm Hg). The PFR for a partially obstructed vein has a resistance equal to that of an unobstructed vein and an opening pressure elevated approximately equal to the pressure obstructing the vein. For perivascular tissue, the PFR has a steep slope (tissue resistance =1,125±1,376 mm Hg/L/hr), while tissue opening pressure depends on the amount of fluid infused. At the onset of fluid extravasation (infiltration), tissue pressure usually is lower than venous pressure (8±8 versus 15±8 mm Hg), until fluid fills the distensible tissue compartment. In clinical practice, when infiltration or obstruction occurs, flow decreases and the clinician adjusts the roller clamp until correct flow resumes; no problem is obvious. The combined model for the intravenous tubing and venous systems explains the behavior of current clinical infusion devices.Presented in part at the Sixth Medical Monitoring Technology Conference, Vail, CO, March 1986; at the Annual Meeting of the American Society of Anesthesiologists, Las Vegas, NV, October 1986; at the Seventh Medical Monitoring Technology Conference, Vail, CO, March 1987; at a meeting on Computers in Critical Care and Pulmonary Medicine, San Diego, CA, June 1987; at the Annual Meeting of the American Society of Anesthesiologists, Atlanta, GA, October 1987; at the Regional Meeting of the Association for the Advancement of Medical Instrumentation, Cincinnati, OH, October 1987; at the Institute of Electrical and Electronics Engineers Ninth Annual Conference of the Engineering in Medicine and Biology Society, Boston, MA, November 1987; and at a meeting of the American Society of Hospital Pharmacists, Atlanta, GA, December 1987.Supported in part by grants from IVAC Corp.The author thanks the following individuals for important intellectual and/or technical assistance: Peter Basser, PhD, Avital Cnaan, PhD, Adriane Concus, MD, John Fox, MD, David Gissen, MD, David Joseph, MD, Anne Kamara, David Leith, MD, Leonard Lind, MD, Richard Morris, MB, BS, Barbara Orlowitz, MEE, Mary Anne Palleiko, RN, Beverly Philip, MD, Daniel Raemer, PhD, David Scott, MB, BS, John Stelling, MPH, and Marie vanRensberg, MB. At IVAC Corp: Walter Bochenko, BSEE, MBA, Robert Butterfield, BSEE, Douglas Christian, RPh, MBA, Alan Davison, BS, David Doan, PhD, Alan Somerville, BSEE, MS, Robin Wernick, BSEE, MS.     

In Vivo Evaluation of a Closed Loop Monitoring Strategy for Induced Paralysis

Objective. Reliable closed loop infusion systems for regulating paralysis level can be a great convenience to the anesthesiologists in automating their task. This paper describes the in vivo performance evaluation of a self-tuning controller that is designed to accommodate large varations in patient drug sensitivity, drug action delays and environmental interfering noise. Methods. The infusion system was evaluated in six adult mongrel dogs. Following the manual induction of paralysis by an anesthesiologist, the controller regulated the infusion of vecuronium to maintain a desired level of paralysis. The integrated EMG response of the hypothenar muscle to a train-of-four stimulation of the ulnar nerve quantified the depth of paralysis. The controller's robustness was tested by contaminating the sensed twitch signal with electrocautery noise and electrode disconnection. Results. The controller reached the initial level of paralysis of 100% in about 4.0 minutes and arrived at the desired level of 90% with an overshoot of 6.38% (±6.82). It maintained the desired level of paralysis with a 2.04% (±1.20) mean offset at 90% and 0.4% (±0.5) mean offset at 80% steady state level, respectively. The mean infusion rate to sustain 90% and 80% paralysis were 2.70 (±2.05) and 2.15 (±2.57) ((mg/kg)/min), respectively. Conclusions. The system adapted to a large variation in the sample subject drug sensitivity. It remained stable despite large amplitude disturbances and maintained the paralysis at the desired level following the removal of the disturbances.     

低钾血症病人的诊断、治疗及护理进展

介绍了低钾血症的诊断、治疗及护理进展。重点阐述了饮食补钾、口服补钾、雾化吸入补钾、肛注补钾、静脉补钾在临床的应用及高浓度快速静脉补钾的安全护理。     

门诊患儿输液应用抗感染药物分析及护理对策

目的 分析儿科门诊输液中抗感染药物应用及护理情况，并探讨护理对策。方法 回顾性总结2002年8月10～20日儿科门诊输液的所有患儿在输液观察室的记录资料。结果 2～7岁是输液患儿的高峰年龄组，患输液的时间比较集中于12：00～18：00和18：00～24：00，抗生素应用占同期输液患总量的97．9％，第3代头孢类抗生素明显多于其他抗生素，联合应用抗病毒药物占60．4％，其中两种抗生素加抗病毒药占11％。结论 为保证儿科门诊输液的工作质量，应(1)重视儿科门诊的输液护理；(2)积极进行健康教育；(3)合理调整班次；(4)促进抗生素合理应用；(5)加强病情观察。     

不同溶媒预冲管路改善血液透析患者皮肤瘙痒的临床观察

目的 观察两种常用的溶媒预冲体外血液循环管路(包括一次性透析器)对改善血液透析患者皮肤瘙痒的临床治疗效果.方法 对22例患者,分为治疗组(11例),采用5%葡萄糖预冲血液透析管路,后进行维持性血液透析;对照组(11例),常规采用0.9%生理盐水预冲血液透析管路,后进行维持性血液透析;每位患者连续观察15次,治疗过程使用的药物包括促红素、透析参数如血流量、透析器及透析机的型号均相同,对两组患者进行瘙痒程度、糖化血红蛋白、血脂、空腹血糖、血补体C3及嗜酸粒细胞计数的比较.结果 5%葡萄糖预冲(治疗组),其透析器显示出较好的相容性,表现在瘙痒程度方面有明显减轻.与0.9%生理盐水预冲(对照组)有显著性差异(P<0.05);但在反应过敏的指标血C3及嗜酸粒细胞计数、糖化血红蛋白、血脂、空腹血糖等方面无显著差异(P>0.05).结论 5%葡萄糖预冲血液透析管路和透析器,能明显减轻血液透析过程中因为使用一次性透析器,导致皮肤瘙痒增高的机率,在短期内对人体血糖和脂代谢影响不明显,相对安全、有效.     

胰岛素瘤切除术围手术期血糖监测的临床意义

【摘要】 目的 探讨胰岛素瘤切除术的围术期管理。方法 回顾性分析本院5年来通过手术治疗胰岛素瘤患者的临床资料。结果 18例患者中男6例,女12例,均有典型的Whipple三联征。15例行开放性肿瘤切除术,3例行腹腔镜下肿瘤切除术。开腹手术采用硬膜外麻醉复合气管内全麻,腹腔镜手术采用单纯气管内全麻。根据术中不同的血糖管理方式将患者分为两组:持续泵注组(C组,n=10)术中静脉泵注50%葡萄糖溶液,根据血糖调节输注速度,维持血糖在3.0~6.0 mmol·L-1;非持续泵注组(NC组,n=8)未予持续泵注葡萄糖,仅在血糖低于2.8 mmol·L-1时才静脉推注50%葡萄糖50 mL。术中每隔15分钟监测一次血糖,肿瘤切除前30 min停止给糖。所有患者术中患者生命体征平稳。持续泵注葡萄糖组肿瘤切除前后血糖控制较非持续泵注稳定(P<0.05)。结论 胰岛素瘤手术时采用持续泵注葡萄糖能够稳定手术过程中血糖水平,肿瘤切除前静脉泵注50%葡萄糖可以避免肿瘤切除前后血糖急剧波动。     

注射贴在静脉输液中的应用观察

[目的 ]观察注射贴在同一病人静脉输液中扩张局部血管和减轻局部疼痛的效果。 [方法 ]观察比较 40例静脉输液病人使用注射贴前后局部血管外径值、局部疼痛的变化。 [结果 ]使用注射贴后局部血管外径大于使用注射贴前 ,两组比较有统计学意义(P <0 .0 0 1) ;使用注射贴后局部疼痛程度也明显轻于使用前 ,两组比较有统计学意义 (P <0 .0 0 1)。 [结论 ]静脉输液前使用注射贴可有效扩张局部血管和局部镇痛。     

Effects of cold pressor test on circulating atrial natriuretic peptide 99–126 (ANP) in patients with Raynaud's phenomenon and influence of treatment with magnesium sulphate and nifedipine

Summary. The effect of a standardized cold pressure test (CPT) on the venous concentration of immunoreactive atrial natriuretic peptide (ir ANP) was studied in 12 females with primary Raynaud's phenomenon (PRP) and 12 female age-matched controls. The test was performed at the end of three stages. During the first stage no medication was given. During the second stage a magnesium infusion was given. After fourteen days of medication with a calcium antagonist (Nifedipine) the third stage of the study was performed. The venous irANP increased significantly (P < 0.05) 10 min after the start of the CPT both in the PRP group and in the control group (136±39 to 159±54 and 153±45 to 179±40 pg ml^-1, given as mean and SD). Baseline irANP did not change in the PRP group after treatment with magnesium or nifedipine. In the control group nifedipine treatment significantly (P < 0 01) lowered venous irANP compared to the no treatment or magnesium sulphate infusion stages (128±31 vs. 153±45 and 160±41 pg ml^-1). After the CPT in both PRP group and control group the venous irANP did not increase either during magnesium sulphate infusion or nifedipine treatment. In conclusion the study has demonstrated that a standardized CPT results in a delayed increase in irANP in venous plasma and that magnesium sulphate infusion and nifedipine treatment prevent this increase. Furthermore, our data do not suggest a role for irANP in the symptomatology of primary Raynaud's phenomenon.     

老年病人术前靶控输注异丙酚镇静不同监测指标的比较

目的:观察在无手术刺激状态下,老年患者靶控输注异丙酚不同镇静程度与效应部位血药浓度(CE)、脑电双频指数(BIS)、平均动脉压(MAP)及心率(HR)的相关性。方法:择期老年手术患者18例,年龄65~78岁,ASAⅠ~Ⅱ级,所行手术不限。全麻诱导前行异丙酚靶控输注(TCI)镇静,靶浓度由0.5 mg/L开始,递增梯度为0.5 mg/L,间隔时间为5 min,直至镇静评分(OAA/S)为0后5 min停止。试验中,监测并记录患者的BIS、MAP、HR值,间隔20 s行OAA/S镇静评分。记录靶控输注系统预测的效应部位浓度值(CE),每变化0.5 mg/L时的数值及时间。结果:①镇静深度的变化与CE、BIS、MAP呈线性回归关系:与CE呈负相关(r=-0.925,P<0.01),与BIS、MAP呈正相关(r=0.858,r=0.564;P均<0.01)。相关性的程度依次为CE>BIS>MAP。HR与OAA/S的变化无显著相关性(P>0.05)。②BIS能很好反映患者镇静深度的变化,可作为其监测的敏感指标。结论:效应部位的异丙酚浓度决定镇静程度的深浅及OAA/S评分的大小,作为新的麻醉镇静深度监测指标,BIS可很好地反映靶控输注异丙酚对老年患者的镇静程度,而作为传统的监测指标,MAP、HR受各种因素的影响较大,灵敏度较差。