Cardiovascular monitoring tools: use and misuse

A History of Fluid Management-From "One Size Fits All" to an Individualized Fluid Therapy in Burn Resuscitation

Fluid management is a cornerstone in the treatment of burns and, thus, many different formulas were tested for their ability to match the fluid requirements for an adequate resuscitation. Thereof, the Parkland-Baxter formula, first introduced in 1968, is still widely used since then. Though using nearly the same formula to start off, the definition of normovolemia and how to determine the volume status of burn patients has changed dramatically over years. In first instance, the invention of the transpulmonary thermodilution (TTD) enabled an early goal directed fluid therapy with acceptable invasiveness. Furthermore, the introduction of point of care ultrasound (POCUS) has triggered more individualized schemes of fluid therapy. This article explores the historical developments in the field of burn resuscitation, presenting different options to determine the fluid requirements without missing the red flags for hyper- or hypovolemia. Furthermore, the increasing rate of co-morbidities in burn patients calls for a more sophisticated fluid management adjusting the fluid therapy to the actual necessities very closely. Therefore, formulas might be used as a starting point, but further fluid therapy should be adjusted to the actual need of every single patient. Taking the developments in the field of individualized therapies in intensive care in general into account, fluid management in burn resuscitation will also be individualized in the near future.

Transthoracic echocardiography in the perioperative setting

PURPOSE OF REVIEW

A need for further assessment of patients in the perioperative setting and an increasing availability of ultrasonography equipment have facilitated the diffusion of ultrasonography and lately focused transthoracic echocardiography (TTE) in anesthesiology practice. This review will discuss the possible use of focused TTE in the perioperative setting and provides an update on present and future perspectives.

RECENT FINDINGS

Several studies focusing on patient management and diagnostic accuracy of perioperative, focused TTE, have been published recently. Several multidisciplinary guidelines addressing use and educational aspects of focused ultrasonography are available, yet guidelines focusing solely on the use in the perioperative setting are lacking.

SUMMARY

Hemodynamically significant cardiac disease or pathophysiology can be disclosed using TTE. Focused TTE is feasible for perioperative patient management and monitoring and will be an inevitable and indispensable tool for the anesthetist. Future research should focus on the outcome of perioperative TTE performed by anesthetists, using rigorous study designs and patient-centered outcomes such as mortality and morbidity.

Critical care in pregnancy--is it different?

In the first part of this review, the epidemiology of obstetric critical care is discussed. This includes the incidence of severe morbidity in pregnancy, identification of critically ill and potentially critically ill patients, the incidence of obstetric ICU admissions, the type of critical illness by stage of pregnancy, ICU admission diagnoses, the severity of illness in obstetric ICU patients compared to non-obstetric patients, ICU mortality of obstetric patients, the ICU proportion of total maternal mortality, and the causes of death for obstetric patients in ICU. In the second part, the management of obstetric patients who happen to be admitted to a general ICU is discussed. Rather than focusing on the management of particular obstetric conditions, general principles of ICU management will be discussed as applied to obstetric ICU patients. These include drug safety, monitoring the fetus, management of the airway, sedation, muscle relaxation, ventilation, cardiovascular support, thromboprophylaxis, and radiology and ethical issues.

Pulmonary artery catheter monitoring in 2011

PURPOSE OF REVIEW

Hemodynamic monitoring has gained widespread acceptance in intensive care units. Despite ongoing debate regarding its safety and efficacy, monitoring with the pulmonary artery catheter (PAC) remains used for the management of severe heart failure and shock.

RECENT FINDINGS

To reanalyze using the most recently published literature in the field, the role of the PAC to manage critically ill patients with right ventricular failure, pulmonary hypertension and weaning failure from cardiac origin. The role of PAC as a gold standard to validate new cardiac output monitoring devices was also reported.

SUMMARY

Despite competition with less invasive hemodynamic monitoring devices or ultrasonic methods, the PAC remains a useful monitoring device in situations in which the knowledge of pulmonary artery pressure, pulmonary artery occlusion pressure and oxygenation parameters are needed. The proper use of PAC requires, however, a perfect knowledge of the numerous pitfalls and difficulties in interpretation of its measurements.

Monitoring in pediatric cardiac critical care: a worldwide perspective

Our ability to directly monitor the mechanisms that govern cellular function, oxygen use, and survival is minimal. Therefore, in critically ill children, surrogate markers are used to try to detect evolving or established hypoxia. These surrogate markers are best used in combination and are complementary to clinical examination. Regardless of resource limitations, we propose that the availability of certain monitoring tools form a standard of care without which pediatric cardiac critical care cannot be safely or optimally provided. These tools include standard invasive hemodynamic monitoring with electrocardiography, lactate measurement, central venous oxygen saturation, and echocardiography. Ultimately, monitoring is only useful when the clinician observes a specific value or trend and has the expertise to act appropriately.

Cardiac output monitoring in newborns

There is an increased interest in methods of objective cardiac output measurement in critically ill patients. Several techniques are available for measurement of cardiac output in children, although this remains very complex in newborns. Cardiac output monitoring could provide essential information to guide hemodynamic management. An overview is given of various methods of cardiac output monitoring with advantages and major limitations of each technology together with a short explanation of the basic principles.

Current use of the pulmonary artery catheter

PURPOSE OF REVIEW

The pulmonary artery catheter is one of the most scrutinized monitors used in intensive care today. Pulmonary artery catheter use is declining due to limited demonstrated beneficial outcomes and the advancement of less invasive monitoring. This study discusses the current use of the pulmonary artery catheter and problems associated with its use including inaccuracy of measurements and data interpretation, inappropriately applied therapeutic interventions, inappropriate delays in applying interventions, and inappropriate patient selection.

RECENT FINDINGS

This overview presents current controversies surrounding the pulmonary artery catheter. It also discusses commonly used monitors and their lack of demonstrated benefits. In addition, data show that intensivists do not have sufficient knowledge to effectively use the pulmonary artery catheter. When utilized in a timely appropriate manner, pulmonary artery catheter monitoring may benefit a selected patient population.

SUMMARY

In summary, the pulmonary artery catheter monitor continues to be used for intensive care patients. To date, no single monitor is associated with an abundance of clear outcome benefits. There are some clinical data showing that the pulmonary artery catheter may still be useful when applied to the right patient population using appropriately timed therapies.

[Volume status and central venous pressure]

Values of intramural or even transmural central venous pressure (CVP) as well as values of pulmonary artery occluded pressure do not correlate with the values of measured circulating blood volume or with responsiveness to fluid challenge. The veins contain approximately 70% of the total blood volume and are 30 times more compliant than arteries, therefore, changes in blood volume within the veins are associated with relatively small changes in venous pressure. The main reason for a lack of correlation between CVP values and blood volume is that the body does everything possible to maintain homeostasis and adequate transmural CVP is a must for cardiovascular function. The most accurate measurement of volume status would be the mean circulatory filling pressure (MCFP), which cannot be measured in a clinical setting. Stressed volume determines MCFP and directly affects venous return and cardiac output whereas unstressed volume is a reserve of blood that can be mobilized into circulation when needed. Both stressed and unstressed volume cannot be adequately measured. Therefore, considering the complexity of the physiologic feedback and clinical picture, robust reflexes and homeostatic mechanisms, CVP is insufficient as a surrogate parameter for assessing the volume status.

Nurse-determined assessment of cardiac output. Comparing a non-invasive cardiac output device and pulmonary artery catheter: a prospective observational study

BACKGROUND

The accurate measurement of Cardiac output (CO) is vital in guiding the treatment of critically ill patients. Invasive or minimally invasive measurement of CO is not without inherent risks to the patient. Skilled Intensive Care Unit (ICU) nursing staff are in an ideal position to assess changes in CO following therapeutic measures. The USCOM (Ultrasonic Cardiac Output Monitor) device is a non-invasive CO monitor whose clinical utility and ease of use requires testing.

OBJECTIVES

To compare cardiac output measurement using a non-invasive ultrasonic device (USCOM) operated by a non-echocardiograhically trained ICU Registered Nurse (RN), with the conventional pulmonary artery catheter (PAC) using both thermodilution and Fick methods.

DESIGN

Prospective observational study.

SETTING AND PARTICIPANTS

Between April 2006 and March 2007, we evaluated 30 spontaneously breathing patients requiring PAC for assessment of heart failure and/or pulmonary hypertension at a tertiary level cardiothoracic hospital.

METHODS

SCOM CO was compared with thermodilution measurements via PAC and CO estimated using a modified Fick equation. This catheter was inserted by a medical officer, and all USCOM measurements by a senior ICU nurse. Mean values, bias and precision, and mean percentage difference between measures were determined to compare methods. The Intra-Class Correlation statistic was also used to assess agreement. The USCOM time to measure was recorded to assess the learning curve for USCOM use performed by an ICU RN and a line of best fit demonstrated to describe the operator learning curve.

RESULTS

In 24 of 30 (80%) patients studied, CO measures were obtained. In 6 of 30 (20%) patients, an adequate USCOM signal was not achieved. The mean difference (+/-standard deviation) between USCOM and PAC, USCOM and Fick, and Fick and PAC CO were small, -0.34+/-0.52 L/min, -0.33+/-0.90 L/min and -0.25+/-0.63 L/min respectively across a range of outputs from 2.6L/min to 7.2L/min. The percent limits of agreement (LOA) for all measures were -34.6% to 17.8% for USCOM and PAC, -49.8% to 34.1% for USCOM and Fick and -36.4% to 23.7% for PAC and Fick. Signal acquisition time reduced on average by 0.6 min per measure to less than 10 min at the end of the study.

CONCLUSIONS

In 80% of our cohort, USCOM, PAC and Fick measures of CO all showed clinically acceptable agreement and the learning curve for operation of the non-invasive USCOM device by an ICU RN was found to be satisfactorily short. Further work is required in patients receiving positive pressure ventilation.

Cardiac output measurement in pediatric anesthesia

Maintenance of cardiovascular stability is crucial to safe anesthetic practice, but measurement of cardiac output has been technically challenging, particularly in pediatric patients. Cardiovascular monitoring has therefore generally relied upon pressure-based measurements, as opposed to flow-based measurements. The measurement of cardiac output under anesthesia and in critical care has recently become easier as a result of new techniques of measurement. This article reviews the basic concepts of and rationale for cardiac output monitoring, and then describes the techniques available for monitoring in clinical practice.

Monitoring the critically ill emergency department patient

Many critically ill patients are remaining in the emergency department for extended periods of time, and delays in diagnosis and/or therapy may increase patient morbidity and mortality. All emergency physicians use monitoring modalities in critically ill patients to detect early cardiovascular compromise and impaired oxygen delivery before disastrous collapse occurs. The authors hope the discussion in this article regarding the monitoring of oxygenation, ventilation, arterial perfusion pressure, intravascular volume, markers of tissue hypoxia, and cardiac output will help the EP provide optimal care for this complicated patient population.

Physiological changes of pregnancy and monitoring

Advances in medical care have led to increasing numbers of complex, high-risk obstetric patients. Specialist training and a sound knowledge of normal maternal physiology are essential to optimize outcomes. One of the earliest observed changes is peripheral vasodilatation; this causes a fall in systemic vascular resistance and triggers physiological changes in the cardiovascular and renal systems, with 40-50% increases in cardiac output and glomerular filtration rates. Safety concerns over Swan Ganz catheters have driven the increasing interest in alternative techniques, such as echocardiography, thoracic bioimpedance and pulse contour analysis, although their exact roles in future obstetric high-dependency care have yet to be established. Analysis of arterial blood gases is fundamental to the management of sick patients, and correct interpretation can be aided by a systematic approach. Observation charts are almost ubiquitous in all aspects of medicine, but little evidence exists to support their use in the high-dependency setting.

Assessment of moderate to severe abdominal blood loss using peripheral to central blood oxygen saturation

PURPOSE

There are various definitions and monitoring modalities for hemodynamic status. Each of them has its own advantages and shortcomings. A new hemodynamic index is proposed in this study. This index can be calculated by placing the measured hemoglobin saturation in a formula. Blood samples for this measurement are taken from arterial, antecubital and central venous blood.

MATERIAL AND METHODS

We calculated this index in three different groups undergoing laparatomy. The control group consisted of patients who underwent elective surgery. The case group with acute internal abdominal bleeding was divided into two groups. Those with more than 20 ml/kg of blood in their abdominal cavity were designated as the severe case group, while those bleeding less were categorized as moderate. Blood samples were taken from ten patients in each group in stable and unstable conditions.

RESULTS

This index differed significantly between dissimilar hemodynamic conditions. The pre-anesthesia value of this index in the control group showed a mean +/- SD of 8.5 +/- 3.2 vs. 1.6 +/- 0.4 in the moderate case group vs. 0.7 +/- 0.08 in the case group with severe hemodynamic changes (p < .001). The index approximated to the control values as the circumstances improved. After compensation for volume loss, pre-extubation values were not significantly different. These were 9.6 +/- 2 in the control group vs. 8 +/- 2 in the case group with moderate hemodynamic change vs. 8 +/- 1.8 in the severe case group. The likelihood ratio of bleeding increased as this index decreased.

CONCLUSION

As the hemodynamic condition deteriorates, this index decreases significantly. This index is an accurate indicator for predicting hemodynamic changes compared to some other modalities. Further investigations are needed into the prognostic and therapeutic advantages of this index.

Inferior vena cava diameter correlates with invasive hemodynamic measures in mechanically ventilated intensive care unit patients with sepsis

Early optimization of fluid status is of central importance in the treatment of critically ill patients. This study aims to investigate whether inferior vena cava (IVC) diameters correlate with invasively assessed hemodynamic parameters and whether this approach may thus contribute to an early, non-invasive evaluation of fluid status. Thirty mechanically ventilated patients with severe sepsis or septic shock (age 60 +/- 15 years; APACHE-II score 31 +/- 8; 18 male) were included. IVC diameters were measured throughout the respiratory cycle using transabdominal ultrasonography. Consecutively, volume-based hemodynamic parameters were determined using the single-pass thermal transpulmonary dilution technique. This was a prospective study in a tertiary care academic center with a 24-bed medical intensive care unit (ICU) and a 14-bed anesthesiological ICU. We found a statistically significant correlation of both inspiratory and expiratory IVC diameter with central venous pressure (p = 0.004 and p = 0.001, respectively), extravascular lung water index (p = 0.001, p < 0.001, respectively), intrathoracic blood volume index (p = 0.026, p = 0.05, respectively), the intrathoracic thermal volume (both p < 0.001), and the PaO(2)/FiO(2) oxygenation index (p = 0.007 and p = 0.008, respectively). In this study, IVC diameters were found to correlate with central venous pressure, extravascular lung water index, intrathoracic blood volume index, the intrathoracic thermal volume, and the PaO(2)/FiO(2) oxygenation index. Therefore, sonographic determination of IVC diameter seems useful in the early assessment of fluid status in mechanically ventilated septic patients. At this point in time, however, IVC sonography should be used only in addition to other measures for the assessment of volume status in mechanically ventilated septic patients.

Oxygen uptake-to-delivery relationship: a way to assess adequate flow

Invasive and noninvasive monitoring facilitates clinical evaluation when resuscitating patients with complex haemodynamic disorders. If the macrocirculation is to be stable, then it must adapt to blood flow or blood flow must be optimized. The objective of flow monitoring is to assist with matching observed oxygen consumption (VO2) to pathophysiological needs. If an adequate balance cannot be maintained then dysoxia occurs. In this review we propose a simple schema for global reasoning; we discuss the limitations of VO2 and arterial oxygen delivery (DaO2) assessment; and we address concerns about increasing DaO2 to supranormal values or targeting pre-established levels of DaO2, cardiac output, or mixed venous oxygen saturation. All of these haemodynamic variables are interrelated and limited by physiological and/or pathological processes. A unique global challenge, and one that is of great prognostic interest, is to achieve rapid matching between observed and needed VO2--no more and no less. However, measuring or calculating these two variables at the bedside remains difficult. In practice, we propose a distinction between three situations. Clinical and blood lactate clearance improvements can limit investigations in simple cases. Intermediate cases may be managed by continuous monitoring of VO2-related variables such as DaO2, cardiac output, or mixed venous oxygen saturation. In more complex cases, three methods can help to estimate the needed VO2 level: comparison with expected values from past physiological studies; analysis of the relationship between VO2 and oxygen delivery; and use of computer software to integrate the preceding two methods.

The critically ill injured patient

Patients admitted to the ICU after severe trauma require frequent procedures in the operating room, particularly in cases where a damage control strategy is used. The ventilatory management of these patients in the operating room can be particularly challenging. These patients often have severely impaired respiratory mechanics because of acute lung injury and abdominal compartment syndrome. Consequently, the pressure and flow generation capabilities of standard anesthesia ventilators may be inadequate to support ventilation and gas exchange. This article presents the problems that may be encountered in patients who have severe abdominal and lung injuries, and the current management concepts used in caring for these patients in the critical care setting, to provide guidelines for the anesthetist faced with these patients in the operating room.

Pulmonary artery catheter versus pulse contour analysis: a prospective epidemiological study

Introduction

The choice of invasive systemic haemodynamic monitoring in critically ill patients remains controversial as no multicentre comparative clinical data exist. Accordingly, we sought to study and compare the features and outcomes of patients who receive haemodynamic monitoring with either the pulmonary artery catheter (PAC) or pulse contour cardiac output (PiCCO) technology.

Methods

We conducted a prospective multicentre, multinational epidemiological study in a cohort of 331 critically ill patients who received haemodynamic monitoring by PAC or PiCCO according to physician preference in intensive care units (ICUs) of eight hospitals in four countries. We collected data on haemodynamics, demographic features, daily fluid balance, mechanical ventilation days, ICU days, hospital days, and hospital mortality. We statistically compared the two techniques.

Results

Three hundred and forty-two catheters (PiCCO 192 and PAC 150) were inserted in 331 patients. On direct comparison, patients with PAC were older (68 versus 64 years of age; p = 0.0037), were given inotropic drugs more frequently (37.3% versus 13%; p < 0.0001), and had a lower cardiac index (2.6 versus 3.2 litres/minute per square meter; p < 0.0001). Mean daily fluid balance was significantly greater during PiCCO monitoring (+659 versus +350 ml/day; p = 0.017) and mechanical ventilation-free days were fewer (12 for PiCCO versus 21 for PAC; p = 0.045). However, after multiple regression analysis, we found no significant effect of monitoring technique on mean daily fluid balance, mechanical ventilation-free days, ICU-free days, or hospital mortality. A secondary multiple logistic regression analysis for hospital mortality which included mean daily fluid balance showed that positive fluid balance was a significant predictor of hospital mortality (odds ratio = 1.0002 for each ml/day; p = 0.0073).

Conclusion

On direct comparison, the use of PiCCO was associated with a greater positive fluid balance and fewer ventilator-free days. After correction for confounding factors, the choice of monitoring did not influence major outcomes, whereas a positive fluid balance was a significant independent predictor of outcome. Future studies may best be targeted at understanding the effect of pursuing different fluid balance regimens rather than monitoring techniques per se.

Ischemic heart disease

Because of changing demographics, increasing numbers of patients with IHD are presenting for noncardiac surgery, and the risks of perioperative morbidity and mortality are significant. The Lee Cardiac Risk Index is applicable in defining perioperative cardiac risk: however, ACC/AHA guidelines may not be applicable comprehensively. The role of biomarkers in risk stratification still needs to be defined. Structured management protocols that help assess, diagnose, and treat patients with IHD preoperatively are likely to help decrease postoperative morbidity and mortality, but clearly are not applicable to all patients. Augmented hemodynamic control with beta-blockers or alpha-2 agonists and modulating inflammation by statins can play an important role in improving outcomes in many patients with IHD; preoperative coronary revascularization may be of limited value. Intraoperative anesthetic management that minimizes hemodynamic perturbations is important; however, the choice of a particular technique typically is not critical. Of critical importance is the postoperative management of the patient. Postoperative myocardial injury should be identified, evaluated, and managed aggressively. Secondary stresses such as sepsis, extubation, and anemia, which can increase demand on the heart, should be treated or minimized. Clearly, optimal care of the patient with IHD entails closely coordinated assessment and management throughout the preoperative, intraoperative, and postoperative phases, if one is to optimize short- and long-term outcomes.

Critical care in the emergency department: monitoring the critically ill patient

The aim of monitoring patients is to detect organ dysfunction and guide the restoration and maintenance of tissue oxygen delivery. Monitoring is a crucial part of the care of the critically ill patient in the emergency department as the physiological response to critical illness is linked strongly to outcome. As it is important to appreciate the limitations of monitoring systems and monitored data, and to understand that invasive monitoring may be hazardous, this review concentrates on the techniques used to monitor critically ill patients in the emergency department. End tidal carbon dioxide monitoring, pulse oximetry, arterial blood pressure monitoring, central venous pressure monitoring, continuous central venous oxygenation saturation monitoring, temperature monitoring, and urine output are discussed. Practitioners should be familiar with the physiology and technology underlying these monitoring techniques and be aware of the pitfalls in interpretation of monitored data.

The clinical application of pulse contour cardiac output and intrathoracic volume measurements in critically ill patients

Cardiac output (CO) determination by pulmonary artery (PA) catheter has increasingly been criticised within the literature due to its invasive nature and poor correlation between the pressure measurements and intravascular volume status in mechanically ventilated patients. Consequently, alternative less invasive technologies to PA catheterisation are emerging within intensive care. One such novel technology are pulse contour CO (PCCO) systems. They establish comprehensive and continuous haemodynamic monitoring utilising a central venous catheter (CVC) and an arterial line. Furthermore, a key feature of this technology is its ability to produce intrathoracic volume measurements which may provide a better estimation of cardiac preload as well as indicate the presence and severity of pulmonary oedema. This article aims to discuss the theoretical basis and clinical application of PCCO systems, how PCCO systems differ from PA catheters and how the intrathoracic volume measurements are derived. Understanding these advanced concepts will ensure that clinicians are able to employ this innovative monitoring technology more effectively.

B-type natriuretic peptide concentrations and myocardial dysfunction in critical illness

B-type natriuretic peptide (BNP) is the first biomarker of proven value in screening for left ventricular dysfunction. The availability of point-of-care testing has escalated clinical interest and the resultant research is defining a role for BNP in the investigation and treatment of critically ill patients. This review was undertaken with the aim of collecting and assimilating current evidence regarding the use of BNP assay in the evaluation of myocardial dysfunction in critically ill humans. The information is presented in a format based upon organ system and disease category. BNP assay has been studied in a spectrum of clinical conditions ranging from acute dyspnoea to subarachnoid haemorrhage. Its role in diagnosis, assessment of disease severity, risk stratification and prognostic evaluation of cardiac dysfunction appears promising, but requires further elaboration. The heterogeneity of the critically ill population appears to warrant a range of cut-off values. Research addressing progressive changes in BNP concentration is hindered by infrequent assay and appears unlikely to reflect the critically ill patient's rapidly changing haemodynamics. Multi-marker strategies may prove valuable in prognostication and evaluation of therapy in a greater variety of illnesses. Scant data exist regarding the use of BNP assay to alter therapy or outcome. It appears that BNP assay offers complementary information to conventional approaches for the evaluation of cardiac dysfunction. Continued research should augment the validity of BNP assay in the evaluation of myocardial function in patients with life-threatening illness.

Recent developments in the perioperative management of the paediatric cardiac patient

PURPOSE OF REVIEW

Survival of infants born with complex cardiac anomalies has dramatically improved, and the growing population of patients with congenital heart disease reaching adulthood has resulted in an increased incidence of long-term complications related to the perioperative period. This review focuses on recent advances in strategies to prevent, detect, treat, or predict early and late complications arising from open heart surgery for congenital heart disease.

RECENT FINDINGS

Aprotinine and recombinant factor VIIa may effectively reduce the risk of excessive perioperative bleeding, and the use of steroids, complement component C4A, heparin-coated circuits, and modified ultrafiltration may play a role in the control of the postoperative inflammatory response. Milrinone is becoming increasingly popular in the prevention and treatment of the reduced postoperative cardiac output, and extracorporeal life support has become a well established and successful form of support for postoperative myocardial dysfunction, even in the functionally univentricular heart. In recent years interest increased in optimizing myocardial protection using contents-differentiated and temperature-differentiated blood cardioplegia and in optimizing cerebral protection using a higher haematocrit during bypass and by using selective regional perfusion in favour of circulatory arrest.

SUMMARY

Hearts can be mended, but salvation of hearts and brains needs further rigorous attention.

Extravascular lung water index: A new method to determine dry weight in chronic hemodialysis patients

To assess the dry weight of chronic hemodialysis (HD) patients, the extravascular lung water index (ELWI) as a volume parameter was investigated to identify fluid overload. Forty-two patients (30 males, 12 females) with a mean age of 55.7+/-13.0 years who were clinically not overhydrated were connected to the PiCCO system before starting HD treatment. We determined ELWI (normal range 3-7 mL/kg) and the following parameters: global end-diastolic volume index (GEDI, normal range 680-800 mL/m(2)) and intrathoracic blood volume index (ITBI, normal range 850-1000 mL/m(2)) before and after HD to assess the volume status. Brain natriuretic peptide (BNP), aldosterone, and renin as vasoactive hormones were measured at the beginning and at the end of HD treatment as well. In 28 of the 42 patients (67%), elevated values of ELWI were found, indicating interstitial volume overload. There were significant correlations between ELWI and cardiac function index (p=0.003; Pearson's coefficient -0.451), global ejection fraction (p=0.012; Pearson's coefficient -0.389), ITBI (p=0.004; Pearson's coefficient 0.437), and GEDI (p=0.004; Pearson's coefficient 0.437). No significant relations among ELWI and mean arterial pressure (MAP), BNP, aldosterone, and renin were found. In conclusion, the use of ELWI is safe in chronic HD patients and identifies fluid-overloaded patients, who show no obvious signs of hypervolemia. The determination of ELWI is an excellent method to quantify the exact volume in chronic HD patients.

Cardiac output monitoring using a brachial arterial catheter during off-pump coronary artery bypass grafting

OBJECTIVE

To investigate the accuracy of cardiac output measurements by transpulmonary thermodilution and pulse contour analysis using a brachial arterial catheter.

STUDY DESIGN

Criterion standard study.

SETTING

University hospital, single institution.

POPULATION

Twenty-three adult patients undergoing off-pump coronary artery bypass grafting.

MEASUREMENTS AND MAIN RESULTS

Cardiac output was measured with a thermistor-tipped brachial arterial catheter using pulse contour analysis (COpc) and transpulmonary thermodilution (COba), which serves to calibrate COpc in the system tested. Both methods were compared separately with standard pulmonary artery thermodilution (COpa). COba was closely correlated with COpa (r = 0.93, p < 0.001). Bland-Altman analysis showed a bias of 0.91 L/min with limits of agreement of +/-0.98 L/min. COpc was also closely correlated (r = 0.80, p < 0.001) with COpa and was found to have a bias of 1.08 L/min with limits of agreement of +/-1.50 L/min. During the surgical procedure, changes in COpa from baseline were closely correlated with changes in COba (r = 0.90, p < 0.01) and COpc (r = 0.81, p < 0.01).

CONCLUSIONS

The brachial arterial access allows a reliable assessment of cardiac output by transpulmonary thermodilution and pulse contour analysis in patients undergoing off-pump coronary artery bypass grafting.

Assessment and management of patients with ischemic heart disease

OBJECTIVE

Review the perioperative management of patients who are scheduled for noncardiac surgery.

DATA SOURCE

Review of literature (PubMed, MEDLINE).

CONCLUSIONS

Patients with ischemic heart disease who undergo noncardiac surgery are at significant risk of perioperative cardiac morbidity and mortality. Recent joint guidelines from the American College of Cardiology and American Heart Association have significantly streamlined the preoperative evaluation processes. Augmented hemodynamic control with intensive perioperative pharmacologic therapy with beta-blockers and possibly alpha-2 agonist has been shown to improve perioperative cardiovascular outcomes. However, translating this information to clinical practice continues to be a challenge and requires a multi- disciplinary approach. A particular intraoperative anesthetic technique is unlikely to influence perioperative cardiac morbidity and mortality. Postoperative management with goals of decreasing hemodynamic stress is important in patients with ischemic heart disease. Diagnosis and management of perioperative myocardial infarction continues to be a challenge. However, use of cardiac specific biomarkers should improve the diagnostic process.