血流动力学监测Hemodynamic monitoring 主要内容血流动力学的基本概念监测技术各种压力波形的识别及分析临床应用血流动力学监测的基本概念定义血流动力学血液流动的物理学血流动力学监测对影响循环系统的物理学因素的监测及解释物理概念流量（Q）压力（P）阻力（R）物理概念压力（P）=流量（Q）×阻力（R）P ：CVP 、LAP/PAWP 、MPAP 、MAP Q ：CO R ：SVR 、PVR 容量与压力的关系阻力与压力的关系阻力与管径的关系生理概念血压=血液流速（心输出量）×循环阻力循环系统是一个连续、相对封闭的管道系统产生血液流动的压力梯度来自于心脏运动产生的压力梯度血管管径能够主动地发生变化神经内分泌活动肾素-血管紧张素-醛固酮系统心脏内的压力梯度心脏活动时的压力变化常用压力监测项目CVP/RAP LAP/PAWP ABP PAP 心脏功能的影响及其调节因素频率/节律前负荷后负荷收缩力前负荷定义：心肌纤维在收缩前的张力决定因素：LVEDV/LVEDP Starling 定律：心肌收缩产生的能量是心肌纤维初长度的函数心肌收缩力与心肌纤维收缩的初长度呈正相关心输出量CO = HR×SV 4-8 L/min SV 60-80 ml 心输出量不等于心肌收缩力SV 的影响因素：前负荷后负荷收缩力后负荷定义：抵抗心脏排血的压力或阻力影响因素：血管内径及血液粘滞性阻力（R = △P/Q ）：SVR = [(MAP-RAP)/CO] × 80 PVR = [(MPAP-LAP)/CO] × 80 心肌收缩力迄今为止，有关心肌收缩力的监测大多是间接实现的射血分数（Ejection Fraction ）一定程度上反映心肌收缩功能不反映心肌的舒张功能SvO2 监测监测部位：肺动脉影响因素：CO 、SaO2 、Hgb 、VO2 意义：反映机体组织水平的氧输送及摄合平衡≥60% 用于计算氧输送（DO2 ）及摄取（VO2 ）氧代谢公式氧含量：CaO2= Hb×1.36 ×SaO2 + 0.003 ×PaO2 CvO2 = Hb × 1.36 ×SvO2 + 0.003 × PvO2 氧输送：DO2 = CO × CaO2 氧摄取：VO2 = CO × (CaO2-CvO2) 影响SvO2 的因素动脉血氧饱和度（SaO2 ）心输出量血红蛋白组织氧摄取能力常用公式及参考范围常用氧代谢参数及参考范围不同休克的变化模式血流动力学监测技术血流动力学监测组成换能器将物理信号（如压力、温度、光）转换为电信号放大器汇集电信号，通过电缆传递给显示设备显示器管道及冲洗系统保持通畅压力袋肝素动脉压监测适应症持续血压监测需要多次抽血动脉测压部位桡动脉、肱动脉、股动脉Allen’s test ：同时压迫桡、尺动脉不断抓握动作直至手指发白放开尺动脉肢端色泽在5-7 秒恢复Allen’s test 护理注意事项波形变化与无创血压对照管道连接检查肢端循环、活动及感觉正确设定报警系统（± 10 to 20mmHg ）穿刺部位固定，防止渗血、血肿正确的动脉压波形快速上升收缩期开始重搏切迹主动脉瓣关闭收缩结束&舒张期开始舒张末期波形最低点并发症出血及血肿血栓形成气栓中心静脉穿刺锁骨下静脉穿刺呼吸影响自主呼吸时，吸气时胸腔及心包压力下降CVP 随之下降（但实际的跨壁压力可能上升）机械通气时的变化与之相反。呼吸末胸腔及心包压力接近于大气压中心静脉导管定位静脉导管位置异常静脉导管位置异常静脉导管位置异常Swan-Ganz 导管Swan-Ganz 导管结构Swan-Ganz 导管放置1区、2区、3区Swan-Ganz 导管放置漂浮导管放置心输出量-热稀释法经右房端口于4秒内注入5-10cc 冰盐水导管顶部感应温度变化计算机自动计算出CO 至少3次测量的平均值（差异<10% ）Swan-Ganz 导管定位Swan-Ganz 的异常位置Swan-Ganz 导管位置异常极其常见，发生率可达25% 。Swan-Ganz 的异常位置Swan-Ganz 导管并发症导管打结气囊破裂瓣膜损伤血小板减少症心动过缓血栓形成导管移位压力波形的识别及分析动脉压力波形1- 收缩压2- 重搏切迹3- 舒张压心房纤颤主动脉瓣关闭不全主动脉瓣狭窄奇脉奇脉哮喘二尖瓣狭窄伴充血性心衰心包填塞大肺动脉栓塞肥厚性心肌病严重左心功能不全中心静脉压（RAP/CVP ）正常范围：2-8 mmHg 波形成份：a- 右房收缩c- 三尖瓣关闭v- 心房充盈y- 三尖瓣开放z- 最接近右心室舒张末压（RVEDP ）中心静脉波形a：出现于P波后，相当于右心室舒张末；c ：出现于QRS 波后；v ：T波之后a-atrial c-contraction v-venous 心动过缓各个波形更加明显x 降支分隔更明显出现h波—舒张中晚期出现的平台h 波本身没有什么临床意义Cannon “a”wave a波异常升高-> 炮波可见于房室脱节、心室起搏等心房纤颤a波消失v 波变化明显由于舒张期不均一导致v波变化不均房扑三尖瓣返流右心室收缩期返流导致c波及v波明显增高严重的返流可能导致c波及v波融合，并表现出类似右心室波形变化的特征三尖瓣狭窄病理生理变化特征—右心房排空延迟平均CVP 升高右心房通常收缩加强导致a波升高由于舒张期心房血向心室内流速减慢使y降支平坦心包缩窄静脉回流受阻平均CVP 升高心腔舒张压趋向于相等明显的a波、v波，x降支及y降支更陡典型的”M”或“W”波形，以及平方根样改变（square root ）心包填塞CVP 趋向于单相变化—明显的x降支及平坦的y降支大量心包积液+限制性心脏疾患Kussmaul’s 征右心室压力低压系统正常收缩压= 20-30 mmHg 正常舒张压= 2-8 mmHg （近似于右房压）右心室波形1- 等容收缩期2- 快速射血期3- 减慢射血期4- 等容舒张期5- 舒张早期6- 心房收缩（a波）7- 舒张末期肺动脉压波形低压系统正常收缩压= 20-30 mmHg (=Sys RV) 正常舒张压= 8-15 mmHg (PAD) 降支出现重搏切迹—肺动脉瓣关闭肺动脉压力波形1- 收缩压2- 重搏切迹3- 舒张压肺动脉压波形右心功能衰竭PAWP 充气时间< 5-10秒波形近似于右心房压力波形正常值= 8-12 mmHg PAWP 波形PAWP PAWP 反应左心室舒张末期压（LVEDP ）PAD/PAWP 的关系1. PAD >>>PAWP —1-4 mmHg 2. PAD/PAWP 差异增大PVR 增加血流增加心率增加PAWP 波形1-a 波2- x 降支3- v 波4- y 降支PAWP->PAP 1-a 波2-c 波3-v 波4- 收缩压5- 舒张压二尖瓣狭窄重度二尖瓣返流概述压力分析不仅仅局限于数字正确地理解压力数值的来源及其意义有助于更好地指导临床对波形的分析能够更深入地理解心脏的生理活动To Swan or not to Swan? Controversies in pulmonary artery catheterization Introduced into clinical practice in 1970. Over two million catheters are sold annually worldwide Helpful in guiding therapy and improving outcome in selected critically ill patients Robin ED: The cult of the Swan–Ganz catheter. Overuse and abuse of pulmonary artery flow catheters. -1985 Lowenstein E: (PA) catheterize or not to (PA) catheterize that is the question. -1980 The Effectiveness of Right Heart Catheterization in the Initial Care ofCritically Ill Patients Connors AF Jr, Speroff T, Dawson NV, et al. JAMA 1996;18:889-97. Outline Objective: To examine the association between the use of PAC during the first 24 hours of care in the intensive care unit (ICU) and subsequent survival, length of stay, intensity of care, and cost of care. Design: Observational study Setting: Five US teaching hospitals between 1989 and 1994. Subjects: 5735 adult patients in ICUs Unadjusted Outcome Matched Pairs Conclusion RHC was associated with increased mortality and increased utilization of resources. The cause of this apparent lack of benefit is unclear. These findings justify reconsideration of a randomized controlled trial of RHC and may guide patient selection for such a study. Debates Patients were not randomized Case matching by initial parameters might not capture physicians’judgments about the initial clinical impression or the patient’s treatment response Without a clear understanding of the skill level in the settings of this study No protocols were described or apparently existed for the use of data generated by the PAC Ethical Dilemma Attempt to perform a RCT was terminated prematurely with nearly half of enrolled controls crossing over to PAC because clinicians deemed it unethical to withhold PAC in the face of clinical deterioration Guyatt G, Ontario Intensive Care Group. A randomized control trial of right-heart catheterization in critically ill patients. J Intensive Care Med 1991;6:91-95 Effectiveness of the Pulmonary Artery Catheter? The Pulmonary Artery Consensus Conference American Association of Critical Care Nurses American College of Chest Physicians American Thoracic Society European Society of Intensive Care Medicine Society of Critical Care Medicine Pulmonary Artery Catheter Consensus Conference. Consensus statement. Crit Care Med. 1997;25:910-925. RECOMMENDATIONS(1) No basis for an FDA moratorium of PAC use Carefully weigh the risks and benefits of the PAC and patients or surrogates should be fully informed before use. Criteria in specific clinical situations should be developed. Clinician knowledge about use of the PAC and its complications should be improved. RECOMMENDATIONS(2) Current training, credentialing, and continuing quality improvement issues related to the PAC should be reevaluated. The indications and contraindications for PAC use where clinical equipoise is lacking should be determined. Clinical trials for indications where clinical equipoise exists should be performed. Financial support for the above projects should be obtained from funding agencies and industry. NHLBI & FDA The highest priority recommendation Implementation of an educational program for clinicians using the PAC The second set of recommendations Identification of diseases, clinical syndromes, and perioperative settings in which prospective randomized trials should be conducted to assess PAC