Search

Transpulmonary thermodilution devices have been widely shown to be accurate in septic shock patients in assessing fluid responsiveness. We conducted a systematic review to assess the relationship between fluid therapy protocols guided by transpulmonary thermodilution devices on fluid balance and the amount of intravenous fluid used in septic shock. We searched MEDLINE, Embase and The Cochrane Library. Studies were eligible for inclusion if they were prospective, parallel trials that were conducted in an intensive care setting in patients with septic shock. The comparator group was either central venous pressure, early goal-directed therapy or pulmonary artery occlusion pressure. Studies assessing only the accuracy of fluid responsiveness prediction by transpulmonary thermodilution devices were excluded. Two reviewers independently performed the search, extracted data and assessed the bias of each study. In total 27 full-text articles were identified for eligibility; of these, nine studies were identified for inclusion in the systematic review. Three of these trials used dynamic parameters derived from transpulmonary thermodilution devices and six used primarily static parameters to guide fluid therapy. There was evidence for a significant reduction in positive fluid balance in four out of the nine studies. From the available studies, the results suggest the benefit of transpulmonary thermodilution monitoring in the septic shock population with regard to reducing positive fluid balance is seen when the devices are utilised for at least 72 hours. Both dynamic and static parameters derived from transpulmonary thermodilution devices appear to lead to a reduction in positive fluid balance in septic shock patients compared to measurements of central venous pressure and early goal-directed therapy.

ObjectiveTo assess the impact of irrigating fluid on hemodynamic profiles using real-time non-invasive cardiac output monitoring (NICOM) in elderly patients undergoing monopolar transurethral resection of the prostate (TURP).MethodsTwenty patients between 65 and 80 years of age who were scheduled for monopolar TURP and received spinal anesthesia up to T10 were enrolled. Irrigating fluid (2.7% sorbitol with 0.5% mannitol solution) was used. Hemodynamic profiles including cardiac index, and stroke volume variation (SVV) using NICOM were obtained. Estimated irrigating fluid absorption was indirectly calculated.ResultsThe median amount of irrigating fluid used was 6000 mL. The median SVV was 11%, which increased to 12% at 10 minutes after initiating surgery. No significant changes in the cardiac index were observed. The estimated absorption of irrigating fluid was almost zero.ConclusionsAlthough the estimated amount of irrigating fluid that was absorbed was negligible, the increase in SVV may indicate intravascular volume depletion with diuresis resulting from mannitol in the irrigating fluid early during irrigation. Therefore, even during short irrigating times, intensive hemodynamic monitoring should be performed to monitor the possibility of intravascular volume depletion as well as volume overload, especially immediately after large amounts of irrigating fluid are used.

Advanced haemodynamic monitoring employing minimally invasive cardiac output measurement may lead to significant improvements in patient outcomes in major surgery. However, the precision (scatter) of measurement of available generic technologies has been shown to be unsatisfactory with percentage error of agreement with bolus thermodilution (% error) of 40% to 50%. Simultaneous measurement and averaging by two or more technologies may reduce random measurement scatter and improve precision. This concept, called the hybrid method, was tested by comparing accuracy and precision of measurement relative to bolus thermodilution using combinations of three component methods. Thirty patients scheduled for either elective cardiac surgery or liver transplantation were studied. Agreement with simultaneous bolus thermodilution of hybrid combinations of continuous thermodilution (QtCCO) or Vigeleo™/FloTrac™ pulse contour measurement (QtFT) with pulmonary Capnotracking (QtCO2) was assessed pre- and post-cardiopulmonary bypass or pre- and post-reperfusion of the donor liver and compared with that of the component methods alone. Hybridisation of QtCO2 (% error 42.2) and QtCCO (% error 51.3) achieved significantly better precision (% error 31.3) than the component methods (P=0.0004) and (P=0.0195). Due to poor inherent precision of QtFT (% error 82.8), hybrid combination of QtFT with QtCO2 did not result in better precision than QtCO2 alone. Hybrid measurement can approach a 30% error, which is recommended as the upper limit for acceptability. This is a practical option where at least one component method, such as Capnotracking, is automated and does not increase the cost or complexity of the measurement process.

The aim of the Cardiac Output Monitoring EvaluaTion-UK (COMET-UK) study was to update reports of cardiac output (CO) monitoring use and to examine whether there is any association between the frequency of CO monitoring use in adult, general intensive care units and patient outcomes. Questionnaires were sent to all intensive care units in England, Wales and Northern Ireland (n=221) asking whether the unit had used CO monitoring in the last two years and, if so, to give details of average frequency of use and which CO monitors were available. The majority of units (n=100, 45.2%) used CO monitoring most days or a few times a week and 33 (14.9%) monitored CO every day (response rate 100%). The most commonly available methods were oesophageal Doppler (n=127, 57.5%), LiDCO (n=96, 43.4%) and PiCCO (n=92, 41.6%). There was no significant difference in risk-adjusted acute hospital mortality (p=0.25) or length of stay (p=0.48) across categories of frequency of use. However for ventilated vs non-ventilated patients and different quartiles of illness severity, there was an association between higher frequency of use and worse outcome among non-ventilated and lowest risk admissions quartiles. The COMET-UK study found that CO monitoring is in common use; however, there was no evidence that more frequent use of CO monitoring was associated with improved outcomes.

Objectives To investigate the level of discomfort/pain in children receiving Ultrasonic Cardiac Output Monitoring (USCOM), as compared to blood pressure measurement. Methods Healthy children, aged 3-12 years old, were recruited from kindergartens and schools as a part of the “Healthy children's vital signs and USCOM values” project. Oscillometric blood pressure was measured, followed by USCOM measurement. The discomfort experienced by the child during each intervention was assessed using the Wong-Baker FACES pain rating scale. The pain scores (scale from 0-5) were compared using Wilcoxon signed rank test. A difference in score of one point was considered to be clinically relevant. Gender differences in pain score were analysed using Mann-Whitney-U test. Results A total of 254 subjects (131 boys, 123 girls) were included. Mean age was 7.9 years with standard deviation (SD) of 2.4 years. The median pain score for USCOM measurement was 1.0 (95% CI=1.0 to 2.0) with interquartile range 1.0 to 2.0. The median pain score for BP measurement was 1.0 (95% CI,=1.0 to 1.0) with interquartile range 0.0 to 2.0. Overall, the pain score associated with USCOM was significantly higher than that associated with BP measurement. However, the difference fails to reach the minimum clinically significant difference of one-point. No significant difference was shown between boys and girls. Conclusion USCOM appears to be tolerated well by healthy children. The discomfort reported during USCOM measurement is comparable to that associated with blood pressure measurements.

As a principal determinant of oxygen delivery and of blood pressure, cardiac output (CO) represents an important hemodynamic variable. Its accurate measurement, therefore, is important to the clinician caring for critically ill patients in a variety of care environments. Though the first clinical measurement of CO occurred 70 years ago, it was the introduction of the pulmonary artery catheter (PAC) with thermodilution-based determination of CO in the 1970s that set the stage for practical and widespread clinical measurement of CO. Although the usefulness and accuracy of this technique have justified its consideration as a “practical” gold standard in CO measurement, its drawbacks have driven the search for newer, less invasive measurement techniques. The last decade has seen the introduction of several such devices into the clinical arena. This article will serve to give a brief review of the history of CO measurement, to provide a discussion of the measurement of accuracy as it relates to CO measurement, and to discuss some of the newer methods and devices for CO measurement and how they have fared against a “practical” gold standard.

The current practice of cardiac output monitoring in critically ill patients was surveyed in 226 adult intensive care units in England and Wales. The response rate was 76% (n=171). Among the responding units, 96% used cardiac output monitoring routinely and 60% had access to more than one monitoring technique. Pulmonary artery catheters were no longer used in one third of the units. More than half of the units (57%) had moved to less invasive techniques. Oesophageal Doppler was used by 35% of the responding units, Lithium indicator Dilution Cardiac Output (LiDCO) by 22% and Pulse-induced Contour Cardiac Output (PiCCO) in 20%. Sixty-one percent of the lead clinicians felt that cardiac output monitoring may alter patient outcome. Two-thirds of units (68%) use superior vena cava oxygen saturation (ScvO2) during initial resuscitation of patients with severe sepsis or septic shock.

The measurement of cardiac output in critical care appears to be increasingly common. However, both the monitoring technologies and the therapeutic approaches they inform have often proved highly controversial. As the range of alternative technologies available continues to increase, it seems worthwhile to question whether this monitoring modality should be used at all. The aim of this pro-con debate is to review the key evidence and to explain the often quite widely differing interpretations placed upon it. The term cardiac output monitoring refers to technology, whose primary purpose is to monitor global blood flow. The principles of the various technologies have been reviewed elsewhere.1

Introduction Cardiac output (CO) is an important indicator of overall cardiac function and intravascular volume status. Present methods of assessing CO at the bedside in older children and adults are invasive and technically unfeasible in the neonate. In recent years, a novel method of measuring cardiac output using a lithium dilution technique and existing vascular access has been developed. The LiDCO/PulseCO system (LiDCO Ltd, Cambridge, UK) of cardiac output monitoring uses an arterial pressure waveform to measure CO on a continuous basis after lithium dilution calibration (LDC). Objective To assess (1) the feasibility of performing LDC using the LiDCO system and (2) the clinical utility of this system and its associated PulseCO software in measuring continuous CO compared to pulsed Doppler echocardiography (PDE) in an extremely preterm animal model. Methods This study used a model of premature infant chronic lung disease as simulated at the SFBR in a 125-day gestation (approximate 25-week human equivalent) baboon model. A total of 10 animals were studied. Each animal had an existing umbilical artery catheter that was connected to the LiDCO system. Initial CO measured using PDE was recorded on all study animals within the first 24 hours of life. Each animal subsequently had an attempt made at LDC according to an established protocol. For those animals in which LDC was unsuccessful, calibration was performed using echocardiography, and CO measurements were serially collected over time and compared to those values obtained using standard PDE. Results LDC/PDE value pairs were successfully obtained in 5 animals. From those animals, 40 PDE/PulseCOvalue pairs were also obtained. There was poor agreement between LDC/PDE pairs and PDE/PulseCOpairs. Lack of agreement between measurements seemed secondary to factors including recirculation of lithium indicator solution from patent ductus arteriosus, variations in flow properties of individual arterial catheters, and variations in the degree of illness of animals. Conclusions Use of LDC and the LiDCO system including continuous cardiac output monitoring is feasible in a premature neonate model. The system was not clinically useful because of a lack of agreement between LDC and PDE measurements, but this may be due to technical factors that can be overcome with more experience. This system may still be a useful tool in neonates if a lack of significant drift over time can be demonstrated after calibration with PDE.