Effect of heparin on arterial blood gases

To evaluate changes in arterial blood gas samples caused by the addition of liquid heparin, 50 patients had three simultaneous blood samples drawn, each with one of three amounts of heparin. The liquid heparin decreased statistically the PCO2, PO2, HCO3, and base excess, while the pH remained unchanged. By using a 2-cc blood sample with a 5-cc glass syringe and a 11/2-inch, 18-gauge needle to draw the heparin solution up to the 2-cc mark, and then completely evacuating it, we found that 0.025 cc of solution remained to coat the syringe. Although this remaining solution would cause a 1.25% error in the blood gas results, the error would be acceptable because it is generally less than the standard deviation of the laboratory results. Excess liquid heparin statistically exaggerated or produced false results consistent with a metabolic acidosis with respiratory compensation. We recommend that the complete evacuation of liquid heparin from the sampling syringe be included when performing an arterial blood gas analysis.     

动脉血气及脉搏氧饱和度监测在内科胸腔镜术中的应用

目的　研究动脉血气及脉搏氧饱和度监测在开放式胸腔镜术中的应用价值。方法　前瞻性监测 15例接受开放式胸腔镜术患者术前、术中、术后的呼吸、血压、心率、ECG、动脉血气、肺功能指标 ,并分析术中脉搏氧饱度变化及其与动脉血气指标的相关性及与手术并发症的关系。结果　 15例患者术前、术中、术后呼吸、脉搏、心率、血压、血气指标 (p H值、Pa O2 、Sa O2 、Pa CO2 )皆无明显变化 ,无显著统计学差异 (P>0 .0 5 ) ;15例患者中有 10例术中出现一过性 ECG变化。出现 ECG变化者术中 30 min BE高于未发生者 ,差异均有显著统计学意义(P<0 .0 5 ) ;心脏并发症的发生与术中 VC<1.0 L、FEV1 <0 .5 L 高度相关 (P<0 .0 5 )。结论　内科胸腔镜术中心脏并发症的发生与患者术中肺功能减低有关 ,单独监测动脉血气分析及脉搏氧饱和度对于预防内科胸腔镜术中心脏并发症的价值有限 ,必需结合肺功能指标进行评估。     

显著高碳酸血症58例次分析

目的　探讨慢性肺部疾病患者对显著高碳酸血症的耐受情况及临床意义。方法　选择 Pa CO2 显著增高 (>75 mm Hg) 5 8例次 ,以有脑部症状的 2 8例次作为观察组 ,无脑部症状的 30例次作为对照组。将两组对比分析。结果　有脑部症状的出现与 p H降低程度、Pa O2 下降程度、以及 Pa CO2 上升速度有关 ,而与 Pa CO2 数值的高低无直接关系。结论　患者可以较好地耐受缓慢上升的显著高碳酸血症     

呼气末正压通气治疗难治性急性肺水肿的临床研究

对31例经常规治疗无效的急性肺水肿（心源性和非心源性）患者,经口或鼻气管插管后给予PEEP通气治疗,PEEP压力一般为5－10mmH2O。观察通气前后动脉血气分析中pH、PaO2、PaCO2、SaO2 的变化,并观察HR、RR、MAP及临床症状的变化。结果：经PEEP通气治疗后,31例患者临床症状均有明显改善,动脉血气分析中pH、PaO2、PaCO2、SaO2治疗前后有显著性差异（P＜0．05）,对MAP无明显影响（P＞0．05）;2例神经源性肺水肿（NPE）患者最终死于多脏器功能衰竭（MOF）。认为应用适当PEEP通气治疗难治性肺水肿,能迅速改善患者症状和低氧血症,是抢救难治性急性肺水肿的有效方法。     

乙醇对大鼠血压和去甲肾上腺素加压反应的影响

目的 探讨乙醇对大鼠动脉血压及去甲肾上腺素加压反应的影响及其可能机制.方法40只雄性Wistar大鼠随机分成四组:对照组(10只),其它三组(各10只)分别给予外源性乙醇0.7g·kg~(-1)·d~(-1),1.4g·kg~(-1)·d~(-1),和2.1g·kg~(-1)·d~(-1)共3个月.分别于1月、2月和3月末测尾动脉电压,3月未取出肠系膜血管网行离体灌注,分别给予去甲肾上腺素1.2×10~(-8)mol/L,1.2×10~(-6)mol/L 100ul,记录反应开始时间,反应持续时间及最高灌注压.结果(1)与对照组比较,经乙醇处理大鼠的动脉血压升高,乙醇日摄入量愈多血压升高愈明显[分别是:收缩压90.07±2.05mmHg,101.98±2.97mmHg,105.51±6.38mmHg,113.97±8.81mmHg,(与对照组比较P均<0.01;乙醇日摄入量最高组比较最低组P<0.01),舒张压80.11±2.42mmHg,90.34±3.77mmHg,91 03±5.01mmHg,91.67±5.37mmHg(与对照组比较P均<0.01)],3个月末时差异仍存在;(2)各实验组大鼠离体肠系膜动脉对去甲肾上腺素反应开始时间无明显差异(P>0.05);(3)与对照组比较,经乙醇处理大鼠离体肠系膜动脉对去甲肾上腺素反应持续时间延长(P均<0.01),乙醇日摄入量愈多延长愈明显(P<0.01);(4)与对照组比较,经乙醇处理大鼠离体肠系膜动脉对去甲肾上腺素反应的最高灌流压升高(P均<0.01),乙醇日摄入量愈     

非心脏手术中直接和间接测量动脉血压在不同血压水平的比较研究

目的：探讨非心脏外科病人麻醉状态下直接法和间接法测得不同水平动脉血压的关系。方法：２７例病人，年龄１７～６３岁。选择左侧或右侧桡动脉穿刺行直接动脉血压连续监测，同时于对侧肱动脉行无创血压测定，两种血压监测均在ＨＰ７８３５４监测仪上同时进行。结果：回归分析所记录的５１２对数据发现：在正常血压水平，两种方法记录的血压相关性好（ｒ＞０．８２，Ｐ＜０．００１），而在高水平的收缩压和平均压，相关性较差（ｒ≤０．７２），上述两种水平血压的直接测量值均比间接测量值高，且随血压的升高，两种方法测量差值进行性增大；对于低水平的收缩压，相关性最差（ｒ＝０．４２），在收缩压直接读数值低于８ｋＰａ（６０ｍｍＨｇ）时，直接测量值可能低于间接测量值。结论：直接法和间接法读数之间存在差异，最大差异出现在收缩压高于或低于正常血压水平时。     

Masked nocturnal hypertension—a novel marker of risk in type 2 diabetes

Aims/hypothesis  This study was designed to evaluate the prevalence of masked nocturnal hypertension (MNHT) and its impact on arterial stiffness and central blood pressure in patients with type 2 diabetes. Methods  Middle-aged patients (n = 414) with type 2 diabetes underwent clinic and ambulatory BP measurements and applanation tonometry. Results  MNHT (clinic BP < 130/80 mmHg and night-time BP ≥ 120/70 mmHg) was found in 7.2% of patients (n = 30). Compared with patients with both clinical and nocturnal normotension (n = 70), patients with MNHT had higher aortic pulse wave velocity (PWV) (10.2 ± 1.8 m/s vs 9.4 ± 1.7 m/s; p = 0.03) and higher central BP (117.6 ± 13.9/74.0 ± 9.1 mmHg vs 110.4 ± 16.4/69.7 ± 9.6 mmHg, p = 0.04). In patients with clinical normotension, night-time systolic BP correlated significantly with PWV. Conclusions/interpretation  Thirty per cent of patients with clinical normotension had nocturnal hypertension. This was accompanied by increased arterial stiffness and higher central BP. We conclude that in clinically normotensive patients with type 2 diabetes, ambulatory BP measurement may help clinicians to identify patients with increased cardiovascular risk.     

动脉血气指标异常对肺栓塞诊断价值的探讨

目的:探讨动脉血气指标对肺血栓栓塞症(PTE)的诊断价值。方法:连续收集2006年1月至2011年3月北京安贞医院急诊监护病房的PTE患者110例,男性56例,平均年龄(64.09±14.02)岁。PTE经肺血管造影计算机断层成像和/或核素肺通气-灌注扫描确诊。同期纳入临床排除PTE的对照56例,男性30例,平均年龄(62.25±10.16)岁。评价反映肺泡过度通气及低氧血症的指标对PTE的诊断价值。结果:所有PTE患者中,与单纯应用PaCO2≤35 mmHg(1 mmHg=0.133 kPa)相比,应用组合指标pH≥7.45(呼吸性)或PaCO2≤35 mmHg可以提高诊断的敏感性(88.2%vs.74.5%,χ2=6.745,P=0.009)。应用SB-AB(标准碳酸氢盐与实际碳酸氢盐之差)≥0.5 mmol/L诊断所有PTE的敏感性与P(A-a)O2(肺泡-动脉氧分压差)异常相似(均为83.6%)。应用组合指标SB-AB≥0.5 mmol/L或P(A-a)O2异常诊断所有PTE的敏感性为96.4%,诊断无心肺疾病PTE的敏感性与阴性预测值均达到100%。结论:评估PTE临床可能性时,不仅要关注ABG指标的绝对值水平,更应寻找反映动态变化的征象。     

Cerebral Autoregulation: From Models to Clinical Applications

Short-term regulation of cerebral blood flow (CBF) is controlled by myogenic, metabolic and neurogenic mechanisms, which maintain flow within narrow limits, despite large changes in arterial blood pressure (ABP). Static cerebral autoregulation (CA) represents the steady-state relationship between CBF and ABP, characterized by a plateau of nearly constant CBF for ABP changes in the interval 60–150 mmHg. The transient response of the CBF–ABP relationship is usually referred to as dynamic CA and can be observed during spontaneous fluctuations in ABP or from sudden changes in ABP induced by thigh cuff deflation, changes in posture and other manoeuvres. Modelling the dynamic ABP–CBFV relationship is an essential step to gain better insight into the physiology of CA and to obtain clinically relevant information from model parameters. This paper reviews the literature on the application of CA models to different clinical conditions. Although mathematical models have been proposed and should be pursued, most studies have adopted linear input–output (‘black-box’) models, despite the inherently non-linear nature of CA. The most common of these have been transfer function analysis (TFA) and a second-order differential equation model, which have been the main focus of the review. An index of CA (ARI), and frequency-domain parameters derived from TFA, have been shown to be sensitive to pathophysiological changes in patients with carotid artery disease, stroke, severe head injury, subarachnoid haemorrhage and other conditions. Non-linear dynamic models have also been proposed, but more work is required to establish their superiority and applicability in the clinical environment. Of particular importance is the development of multivariate models that can cope with time-varying parameters, and protocols to validate the reproducibility and ranges of normality of dynamic CA parameters extracted from these models.     

单一剂量右美托咪定在慢性阻塞性肺病患者撤机中的应用

目的:研究应用单一剂量右美托咪定对慢性阻塞性肺病(COPD)患者拔除气管插管期间的影响。方法:选择COPD合并呼吸衰竭经呼吸机治疗后欲拔除气管插管的40例患者,分为观察组和对照组,各20例。观察组患者拔管前予以0.5μg/kg负荷剂量的右美托咪定,10min注射完毕后开始拔管。监测并记录2组患者用药前(T0)、拔管前(T1)、吸痰后(T2)、拔管后(T3)、拔管后5min(T4)、拔管后10min(T5)、拔管后30min(T6)的呼吸、心率、收缩压、动脉血二氧化碳分压(PaCO2)、氧分压(PaO2)和24h内重插管上机例数。结果:2组患者用药前一般资料和生命体征及血气之间无显著差异;用药导致观察组患者SBP、HR下降,但不影响RR、PaCO2、PaO2;此剂量用药不能完全抑制拔管时吸痰所造成的交感兴奋,但可以减轻幅度,减少再插管率。结论:0.5μg/kg负荷剂量的右美托咪定用于COPD患者脱机时拔管,心血管稳定性较好,在不影响患者呼吸的前提下,有效减轻患者拔管时的血流动力学剧烈变化和继发的二氧化碳潴留及低氧血症,并可能减少由此引发的脱机失败。     

无创正压通气在急性左心衰治疗中的应用

目的探讨无创正压通气（NIPPV）在治疗急性左心衰竭的应用价值。方法将62例急性左心衰竭患者随机分为两组：对照组30例用常规治疗;NIPPV组32例在给予常规治疗基础上加用NIPPV治疗,比较两组治疗前后动脉血气分析、呼吸频率、心率、血压等指标。结果 NIPPV组患者呼吸频率、心率下降,动脉血氧分压（PaO2）上升,动脉二氧化碳分压（PaCO2）下降,治疗总有效率为93.75%（30/32）,对血压无明显影响;对照组治疗总有效率为70.00%（21/30）,两组临床疗效比较差异有统计学意义（P〈0.05）。结论急性左心衰竭时,在常规治疗的基础上联合NIPPV治疗效果显著。     

社区获得性肺炎患者血清合肽素测定的临床意义

目的 探讨测定社区获得性肺炎(CAP)患者血清合肽素的临床意义.方法 收集南京东南大学附属中大医院呼吸科病房2009年3-6月入院的62例CAP患者,男32例,女30例,平均年龄(45±25)岁;对照组为16名健康志愿者,男8名,女8名,平均年龄(41±23)岁.62例CAP患者诊断依据及入院治疗标准符合中华医学会呼吸病学分会制定的"社区获得性肺炎诊断和治疗指南".按肺炎严重指数(PSI)将患者分为:(1)Ⅰ～Ⅲ级组24例;(2)Ⅳ级组20例;(3)Ⅴ级组18例.测定肺炎患者治疗前后及对照组的血清合肽素、血常规、血清超敏C反应蛋白、PaO_2及氧合指数(PaO_2/FiO_2),比较4组相关数值的差异.组间比较采用q检验,治疗前后的比较采用组内配对t检验.结果 治疗前Ⅴ级肺炎患者血清合肽素为(0.91±0.16)μg/L,明显高于Ⅳ级肺炎患者的(0.56±0.11)μg/L、Ⅰ～Ⅲ级肺炎患者的(0.34±0.06)μg/L及对照组的(0.08±0.02)μg/L;治疗后Ⅴ级、Ⅳ级、Ⅰ～Ⅲ级肺炎患者血清合肽素分别为(0.11±0.04)、(0.13±0.05)和(0.07±0.03)μg/L,均较治疗前显著降低.治疗前肺炎患者血清超敏C反应蛋白、白细胞总数均明显高于对照组,治疗后明显下降.治疗前Ⅴ级肺炎患者PaO_2、PaO_2/FiO_2:均明显低于Ⅳ级、Ⅰ～Ⅲ级肺炎患者及对照组,治疗后明显升高.结论 血清合肽素可作为判断社区获得性肺炎患者治疗疗效的一项指标.     

糖尿病患者动脉血压变异和压力反射敏感性的变化

采用指动脉血压监测系统和心血管频谱分析系统测定糖尿病患者动脉收缩压和心搏间距的变异性以及压力反射敏感性。糖尿病性心自主神经病变患者存在明显的动脉收缩压和心搏间距变异性的改变和压力反射敏感性下降，而后者是较早出现改变的指标。     

Prognostic implications of arterial blood gases in acute decompensated heart failure

Background

The prognostic value of arterial blood gases (ABG) in patients with acute decompensated heart failure (ADHF) is not well-established. We therefore conducted the present study to determine the relationship between ABG on admission and long-term mortality in patients with ADHF.

Methods

We studied 588 patients consecutively admitted to our department with ADHF. ABG and classical prognostic variables were determined at patients' arrival to the emergency department. The independent association among the main variables of ABG (pO2, pCO2 and pH) and mortality was assessed with Cox regression analysis.

Results

At a median follow-up of 23 months, 221 deaths (37.6%) were registered. 308 (52.4%), 54 (9.2%) and 50 (8.5%) patients showed hypoxemia (pO2 < 60 mm Hg), hypercapnia (pCO2 > 50 mm Hg) and acidosis (pH < 7.35), respectively. Patients with hypoxemia, hypercapnia and acidosis did not show higher mortality rates (38% vs. 37.1%, 42.6% vs. 37.1%, and 48% vs. 36.6%, respectively; p-value = ns for all comparisons). In multivariate analysis, after adjusting for well-known prognostic covariates, pO2, pCO2 and pH did not show a significant association with mortality. Hazard ratios (HR) for these variables were: pO2, per increase in 10 mm Hg: 0.99 (95% CI: 0.90–1.09), p = 0.861; pCO2, per increase in 10 mm Hg: 1.12 (95% CI: 0.91–1.39), p = 0.262; pH per increase in 0.1: 1.01 (95% CI: 0.99–1.04), p = 0.309. When dichotomizing these variables according to established cut-points, the HR were: hypoxemia (pO2 < 60 mm Hg):1.07 (95% CI: 0.81–1.40), p = 0.637; hypercapnia (pCO2 > 50 mm Hg): 0.98 (95% CI: 0.62–1.57), p = 0.952; acidosis (pH < 7.35): 1.38 (95% CI: 0.87–2.19), p = 0.173.

Conclusion

In patients admitted with ADHF, admission arterial pO2, pCO2 and pH were not associated with all-cause long-term mortality.     

Renin--angiotensin--aldosterone system, RR-interval and blood pressure variability during postural changes after myocardial infarction

Low frequency (LF, 0•04–0•15 Hz) and high frequency(HF, 0•15–0•40 Hz) components of heart ratevariability hate been used to evaluate the autonomic nervoussystem. The sympathico-vagal balance as well as the renin-angiotensin-aldosterone(RAA) axis are disturbed in the post-acute phase of acute myocardialinfarction (AMI). This study examined the relationship betweenthe RAA-axis and spectral indices of the RR-interval and bloodpressure (BP) variabilities during postural manoeuvres in thepost-AMI period. Power spectral analysis of the RR-intervaland BP variability was computed from non-invasive beat-to-beatBP measurements 10–12 days post-AMI, using Fast-Fouriertransforms. Concomitantly, hormonal changes of the RAA-axiswere determined and data were further correlated with the leftventricular ejection fraction. When the patient moved from the lying to the supine positionall RAA-axis parameters significantly increased. Both LF andHF components of total RR-interval variability decreased uponstanding, while the LF component of systolic and diastolic BPvariability increased and HF components remained constant Inthe upright position, plasma renin activity (P<0•01)and angiotensin II (borderline) were inversely related withthe LF component of systolic BP. The aldosterone level was dissociatedfrom plasma renin activity and angiotensin II. The left ventricularejection fraction was inversely correlated (P<0•05)with systolic and diastolic BP variabilities and their LF andHF powers. These results suggest that the renin-angiotensinII system in the post-acute phase of AMI patients treated withaspirin and ß-blocking agents is correlated with cardiovascularautoregulation during postural manoeuvres.     

Inflammatory status, arterial stiffness and central hemodynamics in hypertensive patients with metabolic syndrome

Introduction

Inflammatory state is activated in metabolic syndrome and may explain part of the adverse prognosis of this entity. Arterial stiffness, central blood pressures and wave reflections are independent predictors of cardiovascular risk. This study investigates the relation between low-grade inflammation and arterial stiffness and central hemodynamics in patients with metabolic syndrome.

Methods

We studied 106 consecutive hypertensive patients with metabolic syndrome. Arterial stiffness was assessed by carotid-femoral (c-f) and carotid-radial (c-r) pulse wave velocity (PWV). Central blood pressures were evaluated by pulse wave analysis and heart rate corrected augmentation index (AIx₇₅) was used as a measure of wave reflections. White blood cell count (WBC), high sensitivity C-reactive protein (hsCRP) and fibrinogen were measured as inflammatory markers.

Results

In univariable analysis, PWVc-f correlated with both hsCRP (p < 0.01) and fibrinogen (p < 0.01), while PWVc-r correlated with hsCRP (p = 0.05). Regarding central blood pressures, aortic SBP correlated positively with hsCRP (p < 0.05) and marginally with fibrinogen (p = 0.06) and WBC (p = 0.08). Interestingly, no correlation was found between AIx₇₅ and any of these biomarkers. After adjustment for age, gender, smoking, mean arterial pressure, heart rate, waist circumference, glucose, total and HDL cholesterol, PWVc-f was independently related to hsCRP (p < 0.001) and fibrinogen (p < 0.01), while a marginal independent correlation was also found between PWVc-r and hsCRP (p = 0.06). Furthermore, aortic PP independently associated with fibrinogen (p < 0.05) whereas marginal associations demonstrated between aortic SBP and hsCRP and fibrinogen (p = 0.06 for both).

Conclusion

Inflammatory status is related to arterial stiffness and central blood pressures (but not to augmentation index) in hypertensives with metabolic syndrome. These findings may have implications for increased cardiovascular risk in these patients.     

Evaluation of a short home blood pressure measurement in an outpatient population of hypertensives

Current guidelines suggest the use of home blood pressure monitoring (HBPM) as a method complementary to ambulatory blood pressure monitoring (ABPM) for the identification of arterial hypertension. A cross-sectional study was conducted to evaluate the accuracy of a short HBPM schedule compared with ABPM, and to evaluate to what extent HBPM can replace ABPM. A total of 310 patients who performed ABPM in our hypertension clinic were enrolled between November 2011 and June 2015. They performed a 4-day HBPM schedule, with two readings in the morning and two readings at night. Results showed a moderate correlation between HBPM and ABPM (r = 0.59 for systolic blood pressure (SBP) and r = 0.72 for diastolic blood pressure (DBP)) and moderate diagnostic agreement (area under curve: 0.791 for SBP and 0.857 for DBP). No significant difference was found between first-day average and those of days 2–4. Diagnostic agreement between the two techniques was moderate, supporting the notion that HBPM cannot replace ABPM in the general population. However, we identified two HBPM thresholds, 123/75 and 144/87 mm Hg, through which subjects who may not require further ABPM can be identified.     

低分子肝素对老年重症肺炎患者的临床疗效研究

目的 研究低分子肝素对重症肺炎老年患者的动脉血气分析参数、急性生理学与慢性健康状况评分(APACHEⅡ)评分和预后的影响.方法 选择2012年1月至2015年12月我院老年重症肺炎患者120例,随机分为两组,每组60例.对照组给予常规治疗,观察组在对照组的基础上加用低分子肝素4 000 U皮下注射,每天1次,疗程为7d.比较治疗后1d、3d、7d出血发生率、氧分压、二氧化碳分压、动脉血pH、乳酸、凝血酶时间、凝血酶原时间、纤维蛋白原和APACHEⅡ评分,并观察两组的呼吸机支持时间和死亡情况.结果 观察组的有效率为78.33％,明显高于对照组的51.67％ (P＜0.05);两组患者的出血发生率相比差异无统计学意义(P＞0.05);两组间凝血酶时间、凝血酶原时间、纤维蛋白原在治疗后1d、3d、7d差异均无统计学意义(P＞0.05);两组间二氧化碳分压、pH和乳酸在治疗后1d、3d、7d差异均无统计学意义(P＞0.05);在治疗7d,观察组的氧分压明显高于对照组(P＜0.05);在治疗7d,观察组的APACHEⅡ评分明显低于对照组(P＜0.05);观察组的呼吸机支持时间和病死率均明显低于对照组(P＜0.05).结论 低分子肝素治疗能降低老年重症肺炎患者的APACHEⅡ评分,改善患者的氧合,提高治疗效果,并改善预后.