Interrater reliability of cardiac output measurements by transcutaneous Doppler ultrasound: implications for noninvasive hemodynamic monitoring in the ED

INTRODUCTION: Hemodynamic monitoring is an important aspect of caring for the critically ill patients boarding in the emergency department (ED). The purpose of this study is to investigate the interrater agreement of noninvasive cardiac output measurements using transcutaneous Doppler ultrasound technique. METHODS: This is a prospective observational cohort study performed in a 32-bed adult ED of an academic tertiary center with approximately 65000 annual patient visits. Patients were enrolled after verbal consent over a 7-month period. The raters were ED personnel involved in patient care. Paired measurements of cardiac index (CI) and stroke volume index (SVI) were obtained from a transcutaneous Doppler ultrasound cardiac output monitor. RESULTS: A convenience sample of 107 (50 women and 57 men) patients with a median age of 49 (32, 62) years was enrolled. One hundred two paired measurements were performed in 91 patients in whom adequate Doppler ultrasound signals were obtainable. The raters included 35 emergency medicine attending physicians, 31 emergency medicine residents, 80 medical students, 47 nurses, and 11 emergency medical technicians. Cardiac index range was 0.6 to 5.3 L/min per square meter, and SVI range was 7.7 to 63.0 mL/m(2). The correlation of CI measurements between 2 raters was good (r(2) = 0.87; 95% confidence interval, 0.86-1.00; P < .001). Likewise, SVI measurements between 2 raters also showed acceptable correlation (r(2) = 0.84; 95% confidence interval, 0.81-0.96; P < .001). Interrater reliability was strong for CI (kappa = 0.83 with 92.2% agreement) and SVI measurements (kappa = 0.72 with 88.2% agreement). Most patients had an interrater difference below 10% in CI and SVI measurements. CONCLUSIONS: Emergency department personnel, regardless of their role in patient care, are able to obtain reliable cardiac output measurements in ED patients over a wide range of CI and SVI. Transcutaneous Doppler ultrasound technique may be an alternative to traditional invasive hemodynamic monitoring of critically ill patients presenting to the ED.     

Cost-effectiveness of noninvasive hemodynamic monitoring

Costs for hemodynamic monitoring can comprise a large segment of an institution's budget. Noninvasive monitoring with thoracic electrical bioimpedance is a cost-effective alternative to invasive monitoring. It can decrease not only materials costs but also costs related to patient complications.     

Direct ultrasound application had no effect on cardiac hemodynamic performance in a baseline isolated rat heart model

Therapeutic ultrasound (US) has been used for more than 3 decades to promote tissue healing in cases of tissue injury and muscle soreness. It was previously suggested that US may have vasorelaxatory and inotropic properties. However, the direct effect of therapeutic US in a whole heart model has not yet been investigated. Our hypothesis was that application of US might enhance cardiac function. The Langendorf model was modified in a special manner to allow application of US to the heart. Using this model, 20 male rats were equally divided into two groups. Group 1: the hearts were perfused for 15 min, to obtain baseline measurements, and then they were perfused for another 15 min in a special bath full of perfusate. Group 2: after 15 min of baseline measurements, continuous US of 1 MHz 2 W/cm(2) was applied for another 15 min. The parameters that were measured at 5-min intervals were: left ventricular pressure P(max), first derivative of the rise and fall in left ventricular pressure (dP/dt(max), dP/dt(min)), and pressure-time integral. There was no significant difference between the two groups in all parameters at baseline and during US application. P(max) and dP/dt(max) remained constant. After 15 min of US propagation, P(max) was 98% +/- 3 from baseline level vs. 98% +/- 7 in the control group, and dP/dt(max) was 98% +/- 3 vs. 99% +/- 9 in the control. In dP/dt(min), a gradual decline after 15 min of perfusion was measured. In the US- treated group, it declined to 80% +/- 10 vs. 83% +/- 5 in the controls. In conclusion, US radiation at the dose specified does not improve healthy isolated heart hemodynamic performance. We established a model that may be used for further investigation.     

Timing of hemodynamic pressure measurements on derived hemodynamic parameters

The purpose of this study was to examine the difference between hemodynamic pressures and parameters obtained pre- compared to post-thermodilution CO measurements. A repeated measures within subject design was conducted with a cardiac surgical cohort. Three measures of hemodynamic pressures and parameters were determined pre- and post-CO measurements (Set 1) and repeated in 30 minutes (Set 2). The sequence was duplicated in four hours (Sets 3 and 4). Hemodynamic pressures lower pre-CO were PAS at Sets 1 and 3, and SBP, DBP, and MAP at Set 3. Hemodynamic parameters lower pre-CO were PVRI at Set 1 and SVRI at Set 3. These pre-post CO differences did not vary by greater than 10%. As the CO injectate volume had minimal effect, hemodynamic pressures may be obtained pre- or post-CO to derive hemodynamic parameters.     

Echocardiography in the use of noninvasive hemodynamic monitoring

Invasive pulmonary artery catheter measurements are the standard method for assessment of hemodynamic evaluation at the present time. However, this invasive approach is associated with an increase in patient morbidity and without evidence of a reduction in mortality. Doppler echocardiography is a noninvasive method that provides robust data regarding patients' hemodynamic indices. Several parameters are available for noninvasive hemodynamic evaluation using Doppler echocardiography. Most of these measurements are easily obtained and provide a safe alternative to invasive hemodynamic assessment. As Doppler echocardiography is able to provide additional valuable information, such as cardiac systolic and diastolic function, and the presence of pericardial and pleural effusions, which can play a significant role in the patients’ hemodynamic status, using this noninvasive modality in the daily practice for hemodynamic assessment can prove an alternative to invasive measures in selected patients as well as a complementary tool for those still in need of invasive monitoring.     

Evaluation of myocardial ischemia and viability by noninvasive cardiac imaging

Noninvasive cardiac imaging plays a central role in the diagnosis of coronary artery disease and cardiomyopathy, as well as in the decision making for therapeutic interventions. Proper assessment of the degree of myocardial ischemia and viability is essential to aid in therapies that may improve patient outcomes. In addition, a wealth of evidence exists on the prognostic value of the information obtained from noninvasive imaging. One must utilize an imaging study or studies in an organized fashion, incorporating the latest scientific evidence, guidelines and appropriateness criteria. This review summarizes the advantages, disadvantages and relevant literature on various imaging modalities currently available for the evaluation of myocardial ischemia and viability.     

Improved hemodynamic performance with a novel chest compression device during treatment of in-hospital cardiac arrest

INTRODUCTION: The purpose of this pilot clinical study was to determine if a novel chest compression device would improve hemodynamics when compared to manual chest compression during cardiopulmonary resuscitation (CPR) in humans. The device is an automated self-adjusting electromechanical chest compressor based on AutoPulse technology (Revivant Corporation) that uses a load distributing compression band (A-CPR) to compress the anterior chest. METHODS: A total of 31 sequential subjects with in-hospital sudden cardiac arrest were screened with institutional review board approval. All subjects had received prior treatment for cardiac disease and most had co-morbidities. Subjects were included following 10 min of failed standard advanced life support (ALS) protocol. Fluid-filled catheters were advanced into the thoracic aorta and the right atrium and placement was confirmed by pressure waveforms and chest radiograph. The coronary perfusion pressure (CPP) was measured as the difference between the aortic and right atrial pressure during the chest compression's decompressed state. Following 10 min of failed ALS and catheter placement, subjects received alternating manual and A-CPR chest compressions for 90 s each. Chest compressions were administered without ventilation pauses at 100 compressions/min for manual CPR and 60 compressions/min for A-CPR. All subjects were intubated and ventilated by bag-valve at 12 breaths/min between compressions. Epinephrine (adrenaline) (1mg i.v. bolus) was given at the request of the attending physician at 3-5 min intervals. Usable pressure signals were present in 16 patients (68 +/- 6 years, 5 female), and data are reported from those patients only. A-CPR chest compressions increased peak aortic pressure when compared to manual chest compression (153 +/- 28 mmHg versus 115 +/- 42 mmHg, P < 0.0001, mean +/- S.D.). Similarly, A-CPR increased peak right atrial pressure when compared to manual chest compression (129 +/- 32 mmHg versus 83 +/- 40 mmHg, P < 0.0001). Furthermore, A-CPR increased CPP over manual chest compression (20 +/- 12 mmHg versus 15 +/- 11 mmHg, P < 0.015). Manual chest compressions were of consistent high quality (51 +/- 20 kg) and in all cases met or exceeded American Heart Association guidelines for depth of compression. CONCLUSION: Previous research has shown that increased CPP is correlated to increased coronary blood flow and increased rates of restored native circulation from sudden cardiac arrest. The A-CPR system using AutoPulse technology demonstrated increased coronary perfusion pressure over manual chest compression during CPR in this terminally ill patient population.     

无创血流动力学监测方法在利喜定治疗充血性心力衰竭中的应用

对 30例充血性心力衰竭 (心衰 )患者应用无创血流动力学监测方法评价利喜定扩血管治疗的效果 ,现报告如下。1　病例和方法1.1　病例 :30例患者中男 11例 ,女 19例 ;年龄 5 9～ 82岁 ,平均 6 9.7岁 ;冠心病 2 1例 ,风心病 2例 ,先心病 1例 ,高心病 2例 ,肺心病 4例 ;心功能为 NYHA 级 ;心衰反复发作且本次发作后经常规治疗效果不佳 ;血压≥ 90 / 6 0 m m Hg(1mm Hg=0 .133k Pa)。1.2　治疗方法 :吸氧 ,应用洋地黄、利尿剂。利喜定 2 0 0 mg用生理盐水 10 m l混合后用注射泵持续泵入 ,速度为 1.5～6 .0 m l/ h(10 0～ 4 0 0μg/ min) ,根据…     

无创血流动力学监测系统在急诊科的综合应用分析

目的：探讨无创血流动力学监测系统在急诊科的综合应用价值。方法以房颤患者、心力衰竭患者、冠心病及其合并症患者、机械通气患者和正常对照患者共230例为研究对象,总结分析ANALOGIC无创血流动力学监测系统应用情况,研究选择相关血流动力学参数作统计学分析。结果（1）房颤组与正常对照组比较显示,房颤组心排量（CO）、心脏指数（CI）、搏排量（SV）、心搏指数（SI）、速度指数（VI）、加速指数（ACI）、射血分数（EF）均低于正常对照组,射血前期（PEP）明显延长,左室射血时间（LVET）明显缩短,收缩时间比（STR）增大（P<0.05）;（2）49例心力衰竭患者在监测治疗前后各参数差异有统计学意义（P<0.05）;（3）冠心病组与正常对照组血流动力学参数比较显示,冠心病组系统血管阻力（SVR）、系统血管阻力指数（SVRI）明显增高（P<0.05）,其余指标如CI、CO、SV、VI等有下降趋势,但差异无统计学意义（P>0.05）;冠心病合并症患者亦伴随有CO明显降低,SVR、SVRI明显升高（P<0.05）;（4）机械通气组不同压力支持通气（PSV）对各参数的影响不明显（P>0.05）,不同呼气末正压（PEEP）值对各参数的影响有统计学意义（P<0.05）。结论 ANALOGIC无创血流动力学检测仪操作简单、方便,能进行持续的血流动力学监测,在心衰、冠心病、房颤及机械通气患者中得到了较好应用,值得急诊科进一步推广。     

超声无创心肌做功技术在心脏再同步化治疗的应用

近年来,无创心肌做功逐渐发展为评价心肌收缩功能的新技术。它主要依靠二维斑点追踪超声心动图与左心室压力变化构建左室压力应变环(Pressure-Strain Loop, PVL)评估左心室心肌做功。该技术克服了斑点追踪超声心动图的局限性,对后负荷进行了量化测定,有效克服了负荷依赖性,更好地客观评价心肌的功能。对临床上诊断心血管疾病和评估心血管疾病的预后有着广泛应用和发展前景。     

Effects of intermittent positive-pressure ventilation on cardiac output measurements by thermodilution

Sequential thermodilution measurements of cardiac output in mechanically ventilated patients undergoing cardiac surgery demonstrated a cyclic modulation which correlated with changes in airway pressure, and was not affected by opening the pericardium. There was no satisfactory point for single measurements, which suggests that random thermodilution measurements of cardiac output during intermittent positive-pressure ventilation should be avoided, even when triplicate measurements are performed. To estimate the mean cardiac output, at least two measurements should be made at predetermined points of the ventilatory cycle. We recommend paired measurements at midinspiration and end-expiration.     

应用胸腔阻抗法评估手术和麻醉对患者血流动力学的影响

目的　通过无创心排血量监测仪 ,评价手术和麻醉对腹部择期手术患者血流动力学的影响。方法　应用 He Mo 6 0 1生物阻抗系统 ,分别于术前 1d、术后 4～ 6 h和 2 4 h对 32例腹部择期手术患者进行血流动力学监测 ,并比较心排血量 (CO)、心排指数 (CI)、每搏心排血量 (SV)、每搏心脏做功 (SW)、心脏每分做功(CW、)左室舒张末压 (L VEDP)和心率 (HR)的变化。结果　 CO、CI、CW和 L VEDP在术后 2 4 h内的改变与术前比较均无显著性差异 (P均 >0 .0 5 )。术后 4～ 6 h的 SV和 SW比术前有明显降低 (P均 <0 .0 5 ) ,而术后 2 4 h的 SV和 SW与术前相比则无显著性差异 (P均 >0 .0 5 )。术后 4～ 6 h HR明显快于术前 (P<0 .0 5 ) ,但术后 2 4h HR与术前相比无显著性差异 (P>0 .0 5 )。结论　术后 4～ 6 h SV和 SW值的降低可能与麻醉使心肌收缩力减弱有关 ,HR明显增快则是 SV和 SW降低后机体产生代偿机制的结果。最大程度地保证术中及术后充足的输液量 ,对维持 CO、CI以及维护组织血液灌注具有重要意义。     

Evaluation of noninvasive measurements of oxygenation in stable infants

The accuracy with which transcutaneous measurements of oxygen tension reflect PaO2 in older infants has recently been questioned. We therefore examined the effect of maturation, i.e., age or skinfold thickness, on the accuracy of transcutaneous oxygen tension (PtcO2) and oxygen saturation (StcO2) measurements in 19 infants (age 1 to 61 wk) undergoing elective cardiac catheterization. Twenty-seven simultaneous arterial and transcutaneous measurements revealed a good correlation between PtcO2 and PaO2 (r = .91, slope .77, intercept 3.23 torr). The mean arterial-transcutaneous PO2 difference of 10 torr (range - 15 to 35) was independent of age but was significantly correlated with skinfold thickness (r = .45, p less than .05). There was also a good correlation between StcO2 and SaO2 (r = .95, slope .65, intercept 27.8%). The mean arterial-transcutaneous oxygen saturation of 1.4% (range - 17.3 to 14) was unaffected by age or skinfold thickness. However, neither PtcO2 or StcO2 measurements were accurate in patients with severe hypoxemia; StcO2 consistently overestimated the SaO2 when the SaO2 was below 70%. Thus, in this study the discrepant PtcO2 measurements in older infants were due to increasing skinfold thickness rather than age. PtcO2 monitoring still has an important role in oxygen monitoring and together with StcO2 provides valuable information on oxygenation.     

Localization of cardiac arrhythmias: conventional noninvasive methods

Noninvasive localization of the accessory pathway (AP) in patients with the Wolff-Parkinson-White syndrome and of the site of origin of ventricular tachycardia (VT) is reviewed. 12-lead electrocardiography (ECG) is the most readily available method for localization of both the AP and the site of VT origin. Many published ECG criteria are introduced. The application of body surface potential mapping, vectocardiography, nuclear phase imaging, echocardiography, computed tomography, nuclear magnetic resonance, and signal-averaged ECG in the localization of these arrhythmogenic substrates is also described. We believe that ECG is the most sensitive noninvasive method for AP localization as well as being convenient and simple; it may be used as the only noninvasive method for the initial evaluation. The left lateral AP, which occurs with an incidence of more than 40%, could be localized preoperatively by noninvasive methods only. For localization of the site of VT origin, none of the noninvasive methods is accurate enough for guiding the surgical and catheter-mediated ablative therapies so far.