Pulse pressure variation and stroke volume variation during different loading conditions in a paediatric animal model

Background: Previous studies in adult patients and animal models have demonstrated that pulse pressure variation (PPV) and stroke volume variation (SVV) can be used to predict the response to fluid administration. Currently, little information is available on the performance of these variables in infants and neonates. The aim of our study was to assess whether PPV and SVV can predict fluid responsiveness in an animal model and to investigate the influence of different tidal volumes applied.
Methods: PPV and SVV were monitored by pulse contour analysis in 19 anaesthetized and paralysed piglets during ventilation with tidal volumes ( V _T) of 5, 10 and 15 ml/kg both before and after fluid loading with 25 ml/kg of hydroxy-ethyl starch 6% (HES). Cardiac output was measured by pulmonary artery thermodilution and a positive response to HES infusion was defined as ≥20% increase in the stroke volume index (SVI).
Results: Before HES infusion, PPV and SVV were significantly greater during ventilation with a V _T of 10 and 15 ml/kg than during ventilation with a V _T of 5 ml/kg ( P <0.05). After HES infusion, only ventilation with V _T 15 ml/kg resulted in a significant increase in PPV and SVV. As assessed by receiver operating characteristic curve analysis, SVV during ventilation with V _T 10 ml/kg was the best predictor of a positive response to fluid loading (AUC=0.87).
Conclusions: In this paediatric animal model, we found that SVV during ventilation with 10 ml/kg was a sensitive and specific predictor of the response to fluid loading.     

Effects of norepinephrine on dynamic variables of fluid responsiveness during hemorrhage and after resuscitation in a pediatric porcine model

Background:  The effect of vasopressors on pulse pressure variation (PPV), stroke volume variation (SVV) and on the volumetric variable global end-diastolic volume (GEDV) during changing loading conditions is currently under debate. The aim of our study was to investigate the effect of norepinephrine (NE) on PPV, SVV and GEDV in a pediatric animal model of hemorrhage and resuscitation.
Methods:  Eight anesthetized piglets were studied at normovolemia, after stepwise blood withdrawal (25 ml·kg⁻¹), after infusion of NE to restore mean arterial pressure (MAP), after NE titration was stopped and shed blood was retransfused and finally again after NE titration. Stroke volume (SV) was measured using a thermodilution pulmonary artery catheter. GEDV was measured by transpulmonary thermodilution. PPV and SVV were monitored continuously by pulse contour analysis. In response to NE administration during hemorrhage, MAP significantly increased ( P  < 0.01), PPV significantly decreased ( P  = 0.02), whereas SVV, SV and GEDV remained unchanged. After retransfusion, SVV and GEDV significantly correlated with volume induced percentage change in SV. This significant correlation was reversed after NE administration for SVV and persisted for GEDV. In conclusion, NE administration significantly affected PPV and SVV, whereas the volumetric variable GEDV remained unchanged.     

Effect of elevated PEEP on dynamic variables of fluid responsiveness in a pediatric animal model

Background: Previous studies have demonstrated that stroke volume variation (SVV), pulse pressure variation (PPV) and global end‐diastolic volume (GEDV) can be used to predict the response to fluid administration. Currently, little information is available whether application of different levels of positive end‐expiratory pressure (PEEP), especially in infants and neonates, affects their ability to predict fluid responsiveness. The aim of our study was to assess the effect of increasing PEEP levels on the predictive value of SVV, PPV and GEDV with respect to fluid responsiveness. Methods: Stroke volume variation and PPV were monitored continously in 22 anesthetized piglets during changing PEEP levels (5 and 10 cmH₂O) both before and after fluid loading (FL). GEDV was measured by transpulmonary thermodilution; cardiac output and stroke volume (SV) were measured by pulmonary artery thermodilution. A positive response to FL was defined as ≥15% increase in SV. Results: Fluid loading induced significant changes in all hemodynamic variables except of heart rate and systemic vascular resistance. At PEEP 5 cmH₂O, SVV, PPV and GEDV significantly correlated with volume induced percentage change in SV, whereas at PEEP 10 cmH₂O, this correlation was abolished for PPV. As assessed by receiver operating characteristic curve analysis, SVV and GEDV, independent of PEEP level applied, were the best predictors of a positive response to FL [area under the curve: SVV = 0.88; GEDV = 0.80]. Conclusions: In this pediatric animal model, SVV and GEDV were sensitive and specific predictors of fluid responsiveness during increasing PEEP levels.     

每搏变异度指导肝移植术中液体管理对术后腹内压的影响

目的分析每搏变异度(SVV)指导肝移植术中容量管理后液体平衡的情况,评价该措施对术后腹内压的影响。方法回顾性分析本院2012年8月至2013年l2月ICU 52例肝移植患者的临床资料,手术方式均为非转流经典原位肝移植术,前8个月26例患者以传统指标:心率、血压、中心静脉压(CVP)等指导术中容量管理(对照组,n=26),后8个月26例患者采用脉搏轮廓温度稀释连续心排血量监测(picco)行精确的血流动力学监测,获取能较好反映病人容量状况的动态性指标SVV以指导液体管理(实验组,n=26)。结果 1肝移植术中采用不同血流动力学监测方法均能达到患者的早期目标导向性治疗(EDGT)标准;2术中两组液体治疗均为正平衡,对照组所输注总液体量[(8100±1080)ml]、晶体液量[(6000±985)ml]、人工胶体液量(2500±175)ml]均明显高于实验组[分别为(4700±650)m I、(3800±467)ml、(1000±88)m I,P0.05],而红细胞、血浆、血小板、白蛋白等血制品在两组间比较差异无统计学意义;3对照组手术前后腹内压(mm Hg)分别为:5.05±2.70、15.23±4.32(P0.01),实验组手术后IAP分别为:5.42±2.75、11.08±3.56(P0.01),研究表明两组术前腹内压差异无统计学意义,但对照组术后腹内压明显大于实验组,差异有统计学意义。4Pearson相关分析显示:各组液体治疗正平衡量与术后IAP均呈显著正相关(实验组r=0.62,P0.01;对照组r=0.65,P0.01)。结论采用SVV指导肝移植术中容量管理能减少液体正平衡,减轻术后腹内压的升高幅度。     

不同潮气量通气患者液体治疗时每搏量变异度判断扩容效应的阈值

目的 确定不同潮气量通气患者液体治疗时每搏量变异度(SVV)判断扩容效应的阈值.方法 拟在全麻下行胃肠手术的患者50例,ASA分级Ⅰ或Ⅱ级,年龄20～75岁,随机分为2组(n=25):潮气量8 ml/kg组(V1组)和潮气量10 ml/kg组(V2组).麻醉诱导后以0.4 ml·kg-1·min-1的速率静脉输注6%羟乙基淀粉130/0.4氯化钠注射液,输注量7 ml/kg.于液体治疗前即刻(T1)和液体治疗结束后3 min(T2)时记录MAP、HR、CVP、CI、SVV、每搏指数(SVI)、体循环血管阻力指数(SVRI),计算SVV和CI的变化率(△SVV和△CI).以△CI≥15%为扩容有效标准,绘制SVV判断扩容效应的ROC曲线,确定诊断阈值.结果 ROC曲线分析结果:V1组SVV的诊断阈值为10.5%,判断扩容有效的灵敏度为93.3%,特异度为75.0%;V2组SVV的诊断阈值为13.5%,判断扩容有效的灵敏度为87.5%,特异度为85.7%;V1组SVV判断扩容有效的ROC曲线下面积及其95%可信区间为0.946(0.860～1.031),V2组为0.951(0.868～1.034).V1组和V2组△SVV与△CI呈负性相关,相关系数分别为-0.553和-0.602(P＜0.01).结论 潮气量为8 ml/kg和10 ml/kg机械通气下,SVV判断患者液体治疗时扩容有效的阈值分别为10.5%和13.5%.     

每搏输出量变异评估腹腔高压家猪液体反应性的有效性

目的探讨每搏输出量变异(SVV)评价不同腹腔高压家猪液体反应性的有效性。方法选择实验家猪40只,经颈动脉释放家猪30%血容量,维持家猪低血容量状态,并按随机数字表法随机分为四组,采用氮气气腹法分别维持腹腔压力(IAP)为0 mm Hg(L0组)、15 mm Hg(L15组)、25mm Hg(L25组)和35mm Hg(L35组),稳定30min后给予HES 500 ml液体复苏,采用脉搏轮廓持续心输出量监测(PiCCO)法分别于基线水平、低血容量模型建立后、液体复苏后测家猪SVV以及液体复苏前后每搏输出量(SV)。结果 L0组和L15组家猪SVV与SV呈明显正相关(r分别为0.888和0.942,P0.05),而L25组和L35组SVV与SV均无明显相关性(r分别为0.068和-0.114)。结论 IAP轻度升高(IAP≤15mm Hg)时,SVV可作为评估液体反应性的有效指标,重度腹腔高压(IAP≥25mm Hg)时,SVV不能有效评估液体反应性。     

潮气量负荷试验评估单肺通气患者容量反应性

目的 探讨潮气量负荷试验(V_TC)时的血流动力学变化在评估单肺通气(OLV)容量反应性中的价值。方法 选择择期全身麻醉下行胸腔镜手术患者58例,男25例,女33例,年龄18～64岁,BMI 18～25 kg/m²,ASAⅠ—Ⅲ级。记录OLV 15 min时(V_TC前)、V_TC后2 min(V_TC后)、V_T调回5 ml/kg后2 min[容量负荷试验(VLT)前]和VLT后HR、MAP,应用经食管超声心动图(TEE)测量并记录上述4个时点的食管中段切面左心室流出道(LVOT)直径、胃底长轴切面主动脉瓣速度时间积分(VTI)和每搏量(SV),并计算V_TC前后SV相对变化率(ΔSV-V_TC)、V_TC前后VTI相对变化率(ΔVTI-V_TC)、V_TC前后MAP相对变化率(ΔMAP-V_TC)和VLT前后SV相对变化率(ΔSV-VLT)。根...     

每搏输出量变异度对预测术中液体反应性的指导价值

背景 鉴于越来越多的研究表明中心静脉压(central venous pressure,CVP)等静态血流动力学指标在预测液体反应性方面的不准确性及不实时性,每搏输出量变异度(stroke volume variation,SVV)作为一个功能性血流动力学指标日趋受到重视. 目的 探讨SVV预测术中液体反应性的可靠性及指导价值,为目标靶向治疗提供依据. 内容 综述其基本原理、测量方法、影响因素、不同手术中的应用价值和局限等. 趋向 SVV预测液体反应性的价值日趋受到重视,很可能会替代CVP而成为新的容量预测指标.     

Validation of pulse contour derived stroke volume variation during modifications of cardiac afterload

Background: Left ventricular stroke volume variation (SVV) or its surrogatesare useful tools to assess fluid responsiveness in mechanicallyventilated patients. So far it is unknown, how changes in cardiacafterload affect SVV. Therefore, this study compared left ventricularSVV derived by pulse contour analysis with SVV measured usingan ultrasonic flow probe and investigated the influence of cardiacafterload on left ventricular SVV. Methods: In 13 anaesthetized, mechanically ventilated pigs [31(SD 6)kg], we compared cardiac output (CO), stroke volume (SV), andSVV determined by pulse contour analysis and by an ultrasonicaortic flow signal (Bland–Altman analysis). After obtainingbaseline measurements, cardiac afterload was increased usingphenylephrine and decreased using adenosine (both continuouslyadministered). Measurements were performed with a constant tidalvolume (12 ml kg^–1) without PEEP. Results: Neither increasing mean arterial pressure (MAP) [from 59 (7)to 116 (19)] nor decreasing MAP [from 63 (7) to 39 (4)] affectedCO, SV, and SVV (both methods). Method comparison revealed abias for SVV of 0.1% [standard error of the mean (SE) 0.8] atbaseline, –1.2% (SE 0.8) during decreased and 4.0% (SE0.7) during increased afterload, the latter being significantlydifferent from the others (P < 0.05). Thereby, pulse contouranalysis tended to underestimate SVV during decreased afterloadand to overestimate SVV during increased afterload. Limits ofagreement were approximately 6% for all points of measurement. Conclusions: Left ventricular SVV is not affected by changes in cardiac afterload.There is a good agreement of pulse contour with flow derivedSVV. The agreement decreases, if afterload is extensively augmented.     

每搏输出量变异度监测不同潮气量通气时全麻患者血容量变化的准确性

目的 评价每搏输出量变异度(SVV)监测不同潮气量通气时全麻患者血容量变化的准确性.方法 择期行胃肠手术的全麻患者50例,年龄31～59岁,ASAⅠ或Ⅱ级,随机分为2组:常规潮气量组(C组,n=20)和小潮气量组(L组,n=30).C组潮气量(VT)8 ml/kg,呼吸频率(RR)12次/min,呼气末正压力0,吸入氧浓度80%,氧流量2 L/min,行间歇正压通气;L组VT 6 ml/kg,RR16次/min,余同c组.气管插管后10 min,两组均以0.3 ml·kg-1·min-1的速率静脉输注6%羟乙基淀粉130/0.4氯化钠注射液7 ml/kg,输注后开始手术.于输注前(T1)和输注后10 min(T2)时记录MAP、HR、CVP、体循环血管阻力(SVR)、SVV和每搏指数(SI),并计算其变化率.绘制各项血液动力学指标监测血容量变化的ROC曲线.结果 ROC曲线结果 分析显示:以SI变化率≥25%为监测血容量变化的标准时,SVV的诊断周值为9.5%,C组SVV>9.5%监测血容量变化的灵敏度为100%,特异度为57.1%;L组SVV>9.5%监测血容量变化的灵敏度为91.3%,特异度为71.4%.ROC曲线下面积显示:两组SVV监测血容量变化的准确性高于MAP、HR、CVP、SVR.结论 在常规潮气量(8 ml/kg)和小潮气量(6 ml/kg)/机械通气时,SVV均可准确地监测全麻患者血容量变化.     

极小潮气量机械通气在输尿管软镜手术中的应用

目的评价极小潮气量机械通气策略对输尿管软镜手术患者术中心肺脑功能的影响。方法选择择期气管内插管全麻下行输尿管软镜钬激光碎石术患者74例,男59例,女15例,年龄25～60岁,BMI 18～28 kg/m~2,ASAⅠ或Ⅱ级,根据不同通气方法随机分为三组:常规小潮气量机械通气组(C组,n=20)、间歇通气呼吸暂停组(A组,n=28)和极小潮气量机械通气组(M组,n=26)。术中呼吸参数设置:C组V_T 6 ml/kg,RR 12次/分;A组V_T 6 ml/kg,RR 12次/分,于碎石开始时暂停通气,碎石结束后恢复通气,最大暂停时间5 min,暂停次数依据碎石情况决定;M组V_T 6 ml/kg,RR 12次/分,碎石开始时采用极小潮气量通气模式,V_T 3 ml/kg,RR 24次/分,SpO_2下降至95%时恢复正常通气。分别于麻醉前(T_1)、手术开始前(T_2)、碎石开始前(T_3)、碎石结束后即刻(T_4)、拔管后30 min(T_5)行血气分析,记录pH、PaCO_2,计算氧合指数(OI)、动-静脉氧分压差(Pa-jvO_2)、动静脉血氧饱和度差(Sa-jvO_2)、脑氧摄取率(C_(ER)O_2)。T_1、T_5、术后24 h(T_6)采用ELISA法测定静脉血S100β蛋白、肌红蛋白(MB)、肌酸激酶同工酶(CK-MB)、肌钙蛋白(cTnI、cTnT)浓度。记录激光碎石时间、术者满意程度评分。记录术中不良反应的发生情况。结果与A组比较,T_4时C组和M组PaCO_2明显降低,pH和OI明显升高(P0.05)。与C组比较,A组和M组激光碎石时间明显缩短,术者满意程度评分明显提高(P0.05)。三组不同时点rSO_2、C_(ER)O_2、Pa-jvO_2、Sa-jvO_2、S100β、MB、CK-MB、cTnI、cTnT浓度差异无统计学意义。三组不良反应发生率差异无统计学意义。结论极小潮气量机械通气策略可安全、有效地应用于输尿管软镜手术。     

开颅手术患儿液体治疗时每搏量变异度与脉压变异度的相关性

目的探讨开颅手术实施传统液体治疗和目标导向液体治疗(GDFT)时,患儿每搏量变异度(SVV)与脉压变异度(PPV)的相关性。方法择期行开颅手术患儿60例,男33例,女27例,年龄1～5岁,体重≤20 kg, ASAⅠ或Ⅱ级。术中PPV15%且超过1 min时启动GDFT,给予6%羟乙基淀粉(130/0.4) 3 ml/kg, 10 min内静脉快速输注,如有必要可重复输注。未达启动目标的患儿仍然采用传统的"4-2-1"输液法补充术中液体丢失量。根据患儿是否启GDFT分为:GDFT组和对照组。记录手术开始时(T_1)、钻颅孔前(T_2)、切开硬脑膜前(T_3)、切除肿瘤后(T_4)、缝合硬脑膜前(T_5)、固定骨瓣前(T_6)、手术结束时(T_7)的SVV和PPV,采用Pearson检验分析SVV与PPV的相关性。结果 T_1—T_7时所有患儿SVV与PPV相关系数分别为0.747、0.657、0.376、0.330、0.377、0.333和0.533(P0.05)。共有31例(52%)患儿术中启动GDFT。T_1—T_7时,GDFT组SVV与PPV的相关系数分别为0.815、0.593、0.443、0.362、0.403、0.466和0.463,对照组SVV与PPV的相关系数分别为0.665、0.705、0.282、0.316、0.319、0.241和0.655。结论在开颅手术液体治疗时,患儿SVV与PPV相关性较差,不建议用SVV取代PPV作为启动GDFT的指标。     

Stroke volume variation does not predict fluid responsiveness in patients with septic shock on pressure support ventilation

BACKGROUND: Stroke volume variation (SVV)--as measured by the pulse contour cardiac output (PiCCO) system--predicts the cardiac output response to a fluid challenge in patients on controlled ventilation. Whether this applies to patients on pressure support ventilation is unknown. METHODS: Thirty consecutive patients with septic shock were included. All were on pressure support ventilation, monitored using the PiCCO system and receiving 500 ml of colloid on clinical indications. Arterial pulse contour SVV and the transpulmonary thermodilution cardiac index were measured before and after fluid challenge. RESULTS: Forty-seven per cent of the patients were defined as fluid responders by an observed increase of > 10% in the cardiac index after fluid. Prior to fluid challenge, the cardiac index was lower in responders compared with non-responders (mean +/- SD, 3.0 +/- 0.6 vs. 4.0 +/- 1.2 l/min/m2, P < 0.01). In contrast, pre-infusion values of SVV were similar between subsequent responders and non-responders (13 +/- 5 vs. 16 +/- 6%, P =0.26). The mean areas under the ROC curves were 0.77 (95% confidence interval, 0.60-0.94) and 0.52 (0.30-0.73) for pre-fluid cardiac index and SVV, respectively, indicating a predictive power of only the cardiac index. CONCLUSIONS: SVV did not predict the response in cardiac output to fluid challenge in patients with septic shock on pressure support ventilation.