Invasive Cardiac Output Monitoring Research Articles

Hämodynamisches Monitoring - Neue Aspekte des minimalinvasiven Herzzeitvolumen-Monitorings

The variety of minimally invasive cardiac output (CO) monitoring devices is growing rendering it difficult to keep track of new developments. In this article technical principles, limitations and validation procedures considering new aspects are reviewed. An integrated approach for their use is proposed since no single device can comply with all clinical needs. CO should be interpreted in combination with clinical information and other hemodynamic parameters. It's evident that not the monitor per se, but only the protocol / therapy based on the hemodynamic data can improve patients outcome.

Use of a Minimally Invasive Uncalibrated Cardiac Output Monitor in Patients Undergoing Cesarean Section under Spinal Anesthesia: Report of Four Cases

Hemodynamic changes are observed during cesarean section under spinal anesthesia. Non-invasive blood pressure (BP) and heart rate (HR) measurements are performed to diagnose these changes, but they are delayed and inaccurate. Other monitors such as filling pressure and cardiac output (CO) catheters with external calibration are very invasive or inaccurate. The objective of the present study was to report the cardiac output measurements obtained with a minimally invasive uncalibrated monitor (LiDCO rapid) in patients undergoing cesarean section under spinal anesthesia. After approval by the Ethics Commission, four patients agreed to participate in this study. They underwent cesarean section under spinal anesthesia while at the same time being connected to the LiDCO rapid by a radial artery line. Cardiac output, HR, and BP were recorded at baseline, after spinal anesthesia, after fetal and placental extraction, and after the infusion of oxytocin and metaraminol. We observed a fall in BP with an increase of HR and CO after spinal anesthesia and oxytocin infusion; and an increase in BP with a fall in HR and CO after bolus of the vasopressor. Although this monitor had not been calibrated, it showed a tendency for consistent hemodynamic data in obstetric patients and it may be used as a therapeutic guide or experimental tool.

Clinical evaluation and advancement of perioperative minimally-invasive cardiac output monitoring methods

Background Perioperative cardiac output (CO) monitoring of critical patients is one of the objective indicators of cardiac functions. In recent years, along with the development of software, perioperative minimally-invasive cardiac output monitoring methods get more and more attractive. Objective To summarize the new progress of perioperative minimally-invasive cardiac output monitoring and objectively evaluate their role of perioperative hemodynamic monitoring. Content The basic principle of perioperative minimally-invasive cardiac output monitoring methods (FTV, PiCCO and Modelflow)were summed up.Enumerate the clinical research to compare their accuracy with invasive(Swan-Ganz) or non-invasive(TEE) cardiac output monitoring methods. Estimate the advantages and limitations of three methods. Trend Perioperative minimally -invasive cardiac output monitoring methods are simple and safe, less trauma, high accuracy and can continuously record cardiac output and related hemodynamic parameters. Perioperative minimally-invasive cardiac output monitoring reflect the state of the cardiovascular system promptly and effectively guide therapy in critical patients undergoing anesthesia. It will be more important and widely used in the future. Key words: Cardiac output; Arterial pulse wave; Thermodilution; Modelflow model

Continuous and less invasive cardiac output monitoring by long time interval analysis of a peripheral arterial blood pressure waveform with pulse transit time correction

Continuous and less invasive cardiac output monitoring by long time interval analysis of a peripheral arterial blood pressure waveform with pulse transit time correction

Clinical observation of passive leg raising combined with non invasive cardiac output monitoring system in predicting volume responsiveness

To investigate whether passive leg raising (PLR) combined with ultrasonic cardiac output monitoring system (USCOM) could be used to predict the hemodynamic response to volume expansion (VE) in patients with spontaneous respiration. The study was performed with prospective , cohort study method. Thirty three patients with spontaneous breathing activity who were admitted to the intensive care unit (ICU) from October 2009 to April 2010 were included. Measurements of stroke volume (SV) were obtained with transthoracic echocardiography (TTE) and USCOM. Patients were considered to be responders to VE if SV(TTE) increased ≥ 15%. Based on the responsiveness of VE, all the patients were divided into responders and non responders. The change in SV (ΔSV) after the experiment and its correlation were observed. A total of 36 fluid load tests in 33 patients were evaluated resulting in 24 responders and 12 non responders. There was no significant difference between two groups in the clinical data and hemodynamics parameters at incipient stage when head side of bed was raised for 45 degrees angle.After PLR, the ΔSV(TTE) and ΔSV(USCOM) in responder group were significantly higher than those in non responder group [ΔSV(TTE): (21.7 ± 13.2)% vs. (4.8 ± 9.4)%,ΔSV(USCOM):(23.5 ± 13.0)% vs. (4.6 ± 8.9)%, both P <0.01], with positive correlation between ΔSV( TTE) and ΔSV(USCOM) ( r =0.792, P <0.01). After VE, the ΔSV(TTE)and ΔSV(USCOM) in responder group were significantly higher than those in non responder group [ΔSV(TTE): (27.3 ± 14.1)%vs.(7.2 ± 8.4)%,ΔSV(USCOM): (25.4 ± 13.8)% vs. (6.7 ± 8.6)%, both P <0.01], with positive correlation between ΔSV(TTE) and ΔSV(USCOM) ( r =0.855, P <0.01). The ΔSV(TTE) ≥ 15% during PLR was predictive of response to VE with a sensitivity of 100.0% [95% confidence interval (95% CI) 85.0-100.0] and a specificity of 83.3% (95% CI 68.4-98.2). The ΔSV(USCOM)≥ 15% during PLR was predictive of response to VE with a sensitivity of 83.3% (95% CI 66.1-100.0) and a specificity of 94.4% (95% CI 83.9-100.0). There was no difference between the area under the receiver operating characteristic (ROC) curve for PLR induced ΔSV(TTE)and ΔSV(USCOM) (0.95 ± 0.04 vs. 0.93 ± 0.05, P>0.05). PLR combined with USCOM can predict the hemodynamic response to VE in spontaneously breathing patients, and the procedure can be used to guide fluid therapy in spontaneously breathing patients.

Use of transesophageal Doppler as a sole cardiac output monitor for reperfusion hemodynamic changes during living donor liver transplantation

Aims:To report the use of transesophageal Doppler (TED), a minimally invasive cardiac output (COP) monitor, before, during and after reperfusion and study its effect on anesthetic management during living donor liver transplantation (LDLT).Setting and Design:A prospective observational study.Methods:A total of 25 consecutive recipients with a MELD score between 15 and 20 were enrolled. Data were recorded at baseline (TB); anhepatic phase (TA); and post-reperfusion — 1, 5, 10 and 30 minutes. Fluid therapy was guided by corrected flow time (FTc) of the TED. Packed red blood cells (RBCs) were only given when hematocrit was less than 25%. Rotational thromboelastometry (ROTEM) and standard laboratory tests were used to guide component blood products requirements.Results:Post-reperfusion, the COP, Cardiac Index (CI) and stroke volume (SV) increased significantly at all points of measurements; this was associated with a significant decrease in systemic vascular resistance (SVR) (P ;< .05). Immediately post-reperfusion, for 5 minutes, mean arterial blood pressure (ABP) dropped significantly (P < .05), and 14 out of the 25 patients required boluses of epinephrine (10 μg) to restore the mean ABP; 3 of the 14 patients required norepinephrine infusion till the end of surgery. Central venous pressure (CVP) and urine output (UOP) at all measures were maintained adequately with FTc-guided fluid replacement. Eight out of the 25 patients required no blood transfusion, and 4 of the 8 patients required no catecholamine support.Conclusion:TED as a sole monitor for COP was able to present significant and reliable changes in the cardiovascular status of the recipients during reperfusion, which could help to guide fluid- and drug-supportive therapy in this population of patients. This preliminary study needs to be applied on a larger scale.

Hemodynamic Changes During a Combined Psoas Compartment–Sciatic Nerve Block for Elective Orthopedic Surgery

Hemodynamic variables can theoretically be influenced by a combined psoas compartment-sciatic nerve block (CPCSNB) owing to a relatively high systemic absorption of local anesthetics and extended vasodilatation in the anesthetized limb (hemisympatectomy). In this study we assessed and documented hemodynamic changes during CPCSNB for elective orthopedic surgery. Twenty consecutive patients scheduled for a total hip arthroplasty revision surgery were subjected to a CPCSNB with 150 mg bupivacaine (with epinephrine 1:200.000) 90 minutes before surgery (2 separate single-injection blocks: 30 mg bupivacaine for the sciatic nerve block and 120 mg bupivacaine for the psoas compartment block). Cardiac index, invasive arterial blood pressure, and heart rate were measured at baseline and 60 minutes after puncture using a minimally invasive cardiac output monitoring device (FloTrac/Vigileo™ system (Edwards Lifesciences, Irvine, CA)). Cardiac index did not change after a CPCSNB (preblock cardiac index 2.98 ± 0.54 l · min(-1) · m(-2) versus postblock cardiac index 2.99 ± 0.60 l · min(-1) · m(-2)). There was a significant reduction in mean arterial blood pressure (108 ± 16 mm|Hg vs. 99 ± 16 mm|Hg (P < 0.001)) and diastolic blood pressure (75 ± 9 mm|Hg vs. 68 ± 10 mm|Hg (P = 0.001)). Heart rate increased significantly (68 ± 9 beats · min(-1) vs. 73 ± 10 beats · min(-1) (P = 0.001)). CPCSNB did not affect cardiac index. Changes in arterial blood pressure and heart rate, although statistically significant, remained within an acceptable clinical range (<10% variation). CPCSNB does not appear to induce clinically significant hemodynamic changes in this group of patients.

Cardiac Index Assessment by the Pressure Recording Analytic Method in Unstable Patients With Atrial Fibrillation

Most-Care (powered by the pressure-recording analytic method [PRAM]; Vytech HealthTM, Padova, Italy) is a minimally invasive cardiac output monitoring. This system already has been studied and validated in cardiac surgery and in children. It already showed a correlation with thermodilution methods in hemodynamically unstable patients. The purpose of this study was to confirm the reliability of cardiac index determinations by Most-Care in unstable patients with atrial fibrillation. A prospective study. A teaching hospital. Forty-nine patients. Simultaneous cardiac index measurements by bolus thermodilution and by PRAM from a standard arterial access (radial and femoral) were obtained. The thermodilution cardiac index was calculated as the mean of 3 separate measurements. Because PRAM is a beat-to-beat monitoring system, the mean cardiac index of 12 consecutive beats was considered for the analysis. Correlations were calculated and differences compared by Bland-Altman analysis. Eight patients were excluded because the signal was altered by the arterial catheter resonance so that the study described the remaining 41 patients. The overall estimates of cardiac index measured by PRAM did not show agreement with the reference cardiac index by thermodilution (mean difference = 0.136 L/min/m(2) [0,43 L/min/m(2)-0.15 L/min/m(2)], with an upper limit of agreement of 1.94 L/min/m(2) and a lower limit of agreement of -1.665 L/min/m(2), respectively). The median (interquartile) value of cardiac index assessed by thermodilution was 2.42 L/min/m(2) (2.21-2.98 L/min/m(2)), and by PRAM it was 2.48 L/min/m(2) (1.80-3.00 L/min/m(2), p = 0.6). The authors concluded that PRAM did not compare well with thermodilution in unstable patients with atrial fibrillation.

Minimally Invasive Monitoring of Cardiac Output in the Cardiac Surgery Intensive Care Unit

Cardiac output monitoring in the cardiac surgery patient is standard practice that is traditionally performed using the pulmonary artery catheter. However, over the past 20 years, the value of pulmonary artery catheters has been challenged, with some authors suggesting that its use might be not only unnecessary but also harmful. New minimally invasive devices that measure cardiac output have become available. In this paper, we review their operative principles, limitations, and utility in an integrated approach that could potentially change patients' outcome. However, it is now clear that it is how the monitor is used (ie, the protocol or therapy associated with its use, or its lack thereof), and not the monitor per se, that should be questioned when a patient's outcome is being evaluated.

Bedside assessment of mean systemic filling pressure

The physiology of the venous part of the human circulation seems to be a forgotten component of the circulation in critical care medicine. One of the main reasons, probably, is that measures of right atrial pressure (Pra) do not seem to be directly linked to blood flow. This perception is primarily due to an inability to measure the pressure gradient for venous return. The upstream pressure for venous return is mean systemic filling pressure (Pmsf) and it does not lend itself easily to be measured. Recent clinical studies now demonstrate the basic principles underpinning the measure of Pmsf at the bedside. Using routinely available minimally invasive monitoring of continuous cardiac output and Pra, one can accurately construct venous return curves by performing a series of end-inspiratory hold maneuvers, in ventilator-dependent patients. From these venous return curves, the clinician can now finally obtain at the bedside not only Pmsf but also the derived parameters: resistance to venous return, systemic compliance and stressed volume. Measurement of Pmsf is essential to describe the control of vascular capacitance. It is the key to distinguish between passive and active mechanisms of blood volume redistribution and partitioning total blood volume in stressed and unstressed volume.

Compressing the non-dependent lung during one-lung ventilation improves arterial oxygenation, but impairs systemic oxygen delivery by decreasing cardiac output

We have previously found that compression of the non-dependent lung improves arterial oxygenation during one-lung ventilation (OLV) in patients undergoing esophagectomy. The purpose of this study was to investigate the effects of compression of the non-dependent lung on hemodynamic indices and oxygen delivery using a minimally invasive cardiac output (CO) monitor. Sixteen consecutive patients undergoing esophagectomy through a right thoracotomy were studied. Under general anesthesia, a left-sided double-lumen tube was placed for OLV, and the dependent lung was mechanically ventilated with a tidal volume of 8 ml kg(-1) body weight and a fraction of inspiratory oxygen of 0.8 during OLV. CO was monitored continuously using a FloTrac/Vigileo (Edwards Lifesciences) system. Surgeons compressed the non-dependent lung several times during surgery using a lung retractor to improve exposure of the surgical field. The oxygen delivery index was roughly estimated as the product of the cardiac index (CI) and arterial oxygen saturation as monitored by pulse oximetry (Spo2). Just before non-dependent lung compression, mean (+/- SD) CI and Spo2 were 2.6 +/- 0.6 L min(-1) m(-2) and 95.0 +/- 3.9%, respectively. At 1 min after non-dependent lung compression, Spo2 increased significantly to 97.8 +/- 2.2% (P < 0.05), but CI decreased significantly to 2.0 +/- 0.4 L min(-1) m(-2) (P < 0.05). The product of CI and Spo2 at 1 min was significantly lower (192.7 +/- 37.3) than baseline levels (250.5 +/- 66.3, P < 0.05). Although non-dependent lung compression may be a potentially effective measure to treat hypoxemia during OLV, it should be noted that CO and systemic oxygen delivery may be decreased by this maneuver.

Continuous Invasive Blood Pressure and Cardiac Output Monitoring during Cesarean Delivery: A Randomized, Double-Blind Comparison of Low-dose versus High-dose Spinal Anesthesia with Intravenous Phenylephrine or Placebo Infusion

Continuous Invasive Blood Pressure and Cardiac Output Monitoring during Cesarean Delivery: A Randomized, Double-Blind Comparison of Low-dose versus High-dose Spinal Anesthesia with Intravenous Phenylephrine or Placebo Infusion

Minimally invasive haemodynamic monitoring

Different minimally invasive haemodynamic monitoring techniques are commercially available today and in the recent years they have proved adequate in replacing the pulmonary artery catheter under certain clinical conditions.Moreover, several of these techniques provide additional new parameters primarily related to preload assessment.Therefore, in order to be used in daily clinical practice, the diversity of minimally invasive haemodynamic monitoring requires knowledge of the different techniques, the different parameters provided by the devices and their clinical validity. The aim of the present article is to review the most widely used minimally invasive cardiac output monitoring techniques; emphasize the new parameters available for preload assessment;and propose a modular stepwise monitoring concept.

Perioperative Hemodynamic Monitoring with Transesophageal Doppler Technology

Invasive cardiac output (CO) monitoring, traditionally performed with transpulmonary thermodilution techniques, is usually reserved for high-risk patients because of the inherent risks of these methods. In contrast, transesophageal Doppler (TED) technology offers a safe, quick, and less invasive method for routine measurements of CO. After esophageal insertion and focusing of the probe, the Doppler beam interrogates the descending aortic blood flow. On the basis of the measured frequency shift between the emitted and received ultrasound frequency, blood flow velocity is determined. From this velocity, combined with the simultaneously measured systolic ejection time, CO and other advanced hemodynamic variables can be calculated, including estimations of preload, afterload, and contractility. Numerous studies have validated TED-derived CO against reference methods. Although the agreement of CO values between TED and the reference methods is limited (95% limits of agreement: median 4.2 L/min, interquartile range 3.3-5.0 L/min), TED has been shown to accurately follow changes of CO over time, making it a useful device for trend monitoring. TED can be used to guide perioperative intravascular volume substitution and therapy, with vasoactive or inotropic drugs. Various studies have demonstrated a reduced postoperative morbidity and shorter length of hospital stay in patients managed with TED compared with conventional clinical management, suggesting that it may be a valuable supplement to standard perioperative monitoring. We review not only the technical basis of this method and its clinical application but also its limitations, risks, and contraindications.

Low-dose Spinal Anesthesia with Low-dose Phenylephrine Infusions for Cesarean Delivery: Better but Not Necessarily Best

Low-dose Spinal Anesthesia with Low-dose Phenylephrine Infusions for Cesarean Delivery: Better but Not Necessarily Best

Performance of three minimally invasive cardiac output monitoring systems

We evaluated cardiac output (CO) using three new methods - the auto-calibrated FloTrac-Vigileo (CO(ed)), the non-calibrated Modelflow (CO(mf) ) pulse contour method and the ultra-sound HemoSonic system (CO(hs)) - with thermodilution (CO(td)) as the reference. In 13 postoperative cardiac surgical patients, 104 paired CO values were assessed before, during and after four interventions: (i) an increase of tidal volume by 50%; (ii) a 10 cm H(2)O increase in positive end-expiratory pressure; (iii) passive leg raising and (iv) head up position. With the pooled data the difference (bias (2SD)) between CO(ed) and CO(td), CO(mf) and CO(td) and CO(hs) and CO(td) was 0.33 (0.90), 0.30 (0.69) and -0.41 (1.11) l.min(-1), respectively. Thus, Modelflow had the lowest mean squared error, suggesting that it had the best performance. CO(ed) significantly overestimates changes in cardiac output while CO(mf) and CO(hs) values are not significantly different from those of CO(td). Directional changes in cardiac output by thermodilution were detected with a high score by all three methods.

Critical Care Nephrology: Core Curriculum 2009

In the inpatient setting, a high proportion of nephrology consultations are requested for patients in the Intensive Care Unit (ICU). These patients may have acute kidney injury (AKI) or may be critically ill and have end-stage renal disease (ESRD). Thus, nephrologists need to understand recent evidence-based advances in the field of critical care, as well as areas of ongoing controversy and investigation. In this article, we summarize the diagnosis and management of shock, as well as the management of sepsis, acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and fulminant hepatic failure, all of which are associated with high mortality in the critical care setting. We discuss infectious complications of critical care, including ventilator associated pneumonia and catheter related infections. Supportive care, including nutrition, insulin therapy and anemia management are reviewed. Dialysis considerations in critically ill patients are discussed. Lastly, we review the management of several life-threatening intoxications, many of which require early recognition and consideration of dialysis.

Minimally Invasive Cardiac Output Monitoring in the Perioperative Setting

With advancing age and increased co-morbidities in patients, the need for monitoring devices during the perioperative period that allow clinicians to track physiologic variables, such as cardiac output (CO), fluid responsiveness and tissue perfusion, is increasing. Until recently, the only tool available to anesthesiologists to monitor CO was either a pulmonary artery catheter or transesophageal echocardiograph. These devices have their limitations and potential for morbidity. Several new devices (including esophageal Doppler monitors, pulse contour analysis, indicator dilution, thoracic bioimpedance and partial non-rebreathing systems) have recently been marketed which have the ability to monitor CO noninvasively and, in some cases, assess the patient's ability to respond to fluid challenges. In this review, we will describe these new devices including the technology, studies on their efficacy and the limitations of their use.

Minimally invasive cardiac output monitoring during spinal anaesthesia for Caesarean section

Heart rate and blood pressure are appropriately used as surrogate markers of maternal cardiac output (CO) during spinal anaesthesia (SA) for Caesarean section (CS). Maintenance of baseline maternal blood pressure, using phenylephrine, has been shown to produce the closest to zero umbilical arterial base deficit, despite the fact that phenylephrine may depress maternal cardiac output. However, the maximum change in cardiac output has been shown to correlate better with uteroplacental blood flow than upper arm blood pressure. The maintenance of blood pressure and maternal cardiac output are therefore both important for maternal safety and comfort, and fetal wellbeing. Two studies of cardiac output changes during SA for CS are presented, employing pulse wave form analysis (LiDCOplus, LiDCO Ltd, Cambridge, UK).

Continuous Invasive Blood Pressure and Cardiac Output Monitoring during Cesarean Delivery

Prevention of hemodynamic instability during cesarean delivery during spinal anesthesia has been the aim of several studies. Noninvasive monitoring has been used in all previous studies. This is the first study in healthy pregnant women with continuous invasive recording of arterial blood pressure, cardiac output, and systemic vascular resistance. The aim of this randomized trial was to compare the effects of two different intrathecal doses of bupivacaine, with or without intravenous phenylephrine infusion, on cardiac output and systolic blood pressure. In this double-blinded study, 80 healthy women scheduled to undergo elective cesarean delivery were randomly assigned to one of four different groups receiving 7 mg spinal bupivacaine with or without a concomitant low-dose infusion of phenylephrine (0.25 microg . kg(-1) . min(-1)) or 10 mg spinal bupivacaine with or without phenylephrine infusion. All patients had 4 microg sufentanil added to the spinal solution and had cohydration with 750 ml saline, 0.9%. The low-dose spinal bupivacaine group with intravenous phenylephrine infusion was the most stable group regarding all hemodynamic variables. The authors found significant differences between this group and the group that was given the high dose of bupivacaine with intravenous placebo infusion regarding cardiac output (P = 0.005), systemic vascular resistance (P < 0.0001), and systolic blood pressure (P = 0.012). This study shows that low-dose bupivacaine (with sufentanil), combined with a low-dose infusion of phenylephrine and moderate cohydration, gives the best hemodynamic stability during spinal anesthesia for cesarean delivery.