Evaluation of right-heart catheterization in the critically ill patient without acute myocardial infarction

Application of Cardiovascular Physiology to the Critically Ill Patient

OBJECTIVES

To use the ventricular pressure-volume relationship and time-varying elastance model to provide a foundation for understanding cardiovascular physiology and pathophysiology, interpreting advanced hemodynamic monitoring, and for illustrating the physiologic basis and hemodynamic effects of therapeutic interventions. We will build on this foundation by using a cardiovascular simulator to illustrate the application of these principles in the care of patients with severe sepsis, cardiogenic shock, and acute mechanical circulatory support.

DATA SOURCES

Publications relevant to the discussion of the time-varying elastance model, cardiogenic shock, and sepsis were retrieved from MEDLINE. Supporting evidence was also retrieved from MEDLINE when indicated.

STUDY SELECTION, DATA EXTRACTION, AND SYNTHESIS

Data from relevant publications were reviewed and applied as indicated.

CONCLUSIONS

The ventricular pressure-volume relationship and time-varying elastance model provide a foundation for understanding cardiovascular physiology and pathophysiology. We have built on this foundation by using a cardiovascular simulator to illustrate the application of these important principles and have demonstrated how complex pathophysiologic abnormalities alter clinical parameters used by the clinician at the bedside.

Variation in Hemodynamic Assessment and Interpretation: A Call to Standardize the Right Heart Catheterization

BACKGROUND

Invasive hemodynamic measurement via right heart catheterization has shown divergent data in its role in the treatment of patients with heart failure (HF) and cardiogenic shock. We hypothesized that variation in data acquisition technique and interpretation might contribute to these observations. We sought to assess differences in hemodynamic acquisition and interpretation by operator subspecialty as well as level of experience.

METHODS AND RESULTS

Individual-level responses to how physicians both collect and interpret hemodynamic data at the time of right heart catheterization was solicited via a survey distributed to international professional societies in HF and interventional cardiology. Data were stratified both by operator subspecialty (HF specialists or interventional cardiologists [IC]) and operator experience (early career [≤10 years from training] or late career [>10 years from training]) to determine variations in clinical practice. For the sensitivity analysis, we also look at differences in each subgroup. A total of 261 responses were received. There were 141 clinicians (52%) who self-identified as HF specialists, 99 (38%) identified as IC, and 20 (8%) identified as other. There were 142 early career providers (54%) and late career providers (119 [46%]). When recording hemodynamic values, there was considerable variation in practice patterns, regardless of subspecialty or level of experience for the majority of the intracardiac variables. There was no agreement or mild agreement among HF and IC as to when to record right atrial pressures or pulmonary capillary wedge pressures. HF cardiologists were more likely to routinely measure both Fick and thermodilution cardiac output compared with IC (51% vs 29%, P < .001), something mirrored in early career vs later career cardiologists.

CONCLUSIONS

Significant variation exists between the acquisition and interpretation of right heart catheterization measurements between HF and IC, as well as those early and late in their careers. With the growth of the heart team approach to management of patients in cardiogenic shock, standardization of both assessment and management practices is needed.

Accuracy of a noninvasive estimated continuous cardiac output measurement under different respiratory conditions: a prospective observational study

PURPOSE

The estimated continuous cardiac output (esCCO) system was recently developed as a noninvasive hemodynamic monitoring alternative to the thermodilution cardiac output (TDCO). However, the accuracy of continuous cardiac output measurements by the esCCO system compared to TDCO under different respiratory conditions remains unclear. This prospective study aimed to assess the clinical accuracy of the esCCO system by continuously measuring the esCCO and TDCO.

METHODS

Forty patients who had undergone cardiac surgery with a pulmonary artery catheter were enrolled. We compared the esCCO with TDCO from mechanical ventilation to spontaneous respiration through extubation. Patients undergoing cardiac pacing during esCCO measurement, those receiving treatment with an intra-aortic balloon pump, and those with measurement errors or missing data were excluded. In total, 23 patients were included. Agreement between the esCCO and TDCO measurements was evaluated using Bland-Altman analysis with a 20 min moving average of the esCCO.

RESULTS

The paired esCCO and TDCO measurements (939 points before extubation and 1112 points after extubation) were compared. The respective bias and standard deviation (SD) values were 0.13 L/min and 0.60 L/min before extubation, and - 0.48 L/min and 0.78 L/min after extubation. There was a significant difference in bias before and after extubation (P < 0.001); the SD before and after extubation was not significant (P = 0.315). The percentage errors were 25.1% before extubation and 29.6% after extubation, which is the criterion for acceptance of a new technique.

CONCLUSION

The accuracy of the esCCO system is clinically acceptable to that of TDCO under mechanical ventilation and spontaneous respiration.

A Novel Method for Estimating Right Atrial Pressure With Point-of-Care Ultrasound

BACKGROUND

Current noninvasive estimation of right atrial pressure (RAP) by either bedside jugular venous pressure exam or inferior vena cava measurement during a comprehensive echocardiogram offers imprecise estimates of actual RAP.

METHODS

We enrolled 41 patients in a prospective, blinded study to validate a novel point-of-care ultrasound method using direct right atrial depth (RAD) measurement and jugular venous ultrasound to estimate RAP. Two subjects were excluded, and 39 were included in the final analysis. A parasternal long-axis view was obtained, and the depth of the noncoronary cusp attachment to the posterior left ventricular outflow tract was recorded as the RAD. This was added to an estimate of the jugular venous pressure obtained during a jugular vein ultrasound to calculate an estimated RAP (RAP_US). The RAP_US was compared to the RAP measurement during right heart catheterization (RAP_cath) both as measured and as corrected for where the catheter was zeroed.

RESULTS

The correlation coefficient between RAP_cath and RAP_US was +0.75; regression R², 0.56; and bias, -0.49 mm Hg (95% CI, -1.42 to +0.43 mm Hg), with the limits of agreement -5.56 to +7.24 mm Hg and accuracy of 3 mm Hg or less in 29 (74%) of the subjects. For the RAP_US corrected for the catheter zero point, the correlation coefficient between RAP_cath and RAP_US was +0.72; regression R², 0.52; and bias, -0.60 mm Hg (95% CI, -1.60 to +0.39 mm Hg), with the limits of agreement -5.56 to +7.24 mm Hg and accuracy of 3 mm Hg or less in 26 (67%) of the subjects.

CONCLUSION

This simple ultrasound evaluation of RAD and the right jugular vein correlates well with actual RAP and can accurately estimate RAP within 3 mm Hg in most patients. This has the potential to improve our bedside volume status exam, as well as improve the accuracy of RAP estimation during comprehensive echocardiogram.

The Identical External Reference Point Standardized to the Zero-Reference Level for Measuring Both Central and Jugular Venous Pressures: An Observational Study

Background

Studies report discrepancies between CVP and JVP measurements. The mid-thoracic plane (MTP) at the anterior fourth intercostal space level indicates the zero-reference level (ZRL) for venous pressure measurement, and the midaxillary line (MAL) at fourth intercostal space is a point near the ZRL in the supine position. JVP is usually measured from the sternal angle (SA) with further addition of 5 cm (JVP-SA + 5) and CVP in the supine position from MAL (CVP-MAL). However, no report has compared CVP measured from MTP (CVP-MTP) with CVP-MAL and with JVP from MTP (JVP-MTP) and JVP-SA + 5.

Methods

We measured JVP-MTP and JVP-SA + 5 in appropriate reclining positions and subsequently CVP-MTP and CVP-MAL in the supine position blindly in 150 patients. We compared the pressures by Pearson correlation and Bland-Altman plots.

Results

CVP-MTP and CVP-MAL demonstrated similar means (p = 0.129), strong positive linear relationship (r = 0.908), and good agreement (near-zero mean difference) with each other. JVP-MTP was about 1 cm higher than JVP-SA + 5 (p < 0.001). JVP-MTP displayed higher correlation coefficients and better agreements with both CVPs than JVP-SA+5. Correlation coefficients and mean differences of both CVPs with JVP-MTP were almost equal, about 0.83 and 1 cm, and with JVP-SA + 5 also almost equal, about 0.72 and 2 cm, respectively.

Conclusions

JVP tallies better with CVP examined in the supine position when both are measured from MTP as the identical external reference point (ERP), and MAL can be used as MTP to measure CVP in the supine position. Our findings indicate the way to explore the matching of CVP and JVP to the full extent possible by standardizing their measurements from other identical ERPs to that from the zero-reference level MTP. Their further study in similar higher reclining positions from identical ERPs, such as MTP, MAL, and SA with the addition of higher numbers instead of 5 cm, is warranted standardizing other measurements to that from MTP.

Testing Biased Randomization Assumptions and Quantifying Imperfect Matching and Residual Confounding in Matched Observational Studies

One central goal of design of observational studies is to embed non-experimental data into an approximate randomized controlled trial using statistical matching. Despite empirical researchers' best intention and effort to create high-quality matched samples, residual imbalance due to observed covariates not being well matched often persists. Although statistical tests have been developed to test the randomization assumption and its implications, few provide a means to quantify the level of residual confounding due to observed covariates not being well matched in matched samples. In this article, we develop two generic classes of exact statistical tests for a biased randomization assumption. One important by-product of our testing framework is a quantity called residual sensitivity value (RSV), which provides a means to quantify the level of residual confounding due to imperfect matching of observed covariates in a matched sample. We advocate taking into account RSV in the downstream primary analysis. The proposed methodology is illustrated by re-examining a famous observational study concerning the effect of right heart catheterization (RHC) in the initial care of critically ill patients. Code implementing the method can be found in the supplementary materials.

The Physical Examination to Assess for Anemia and Hypovolemia

Hypovolemia develops with the loss of extracellular fluid volume or blood. Rapidly identifying hypovolemia can be lifesaving. Indicators of hypovolemia on examination include supine or postural hypotension, increase in heart rate by 30 beats per minute or severe dizziness with standing, and a decrease in central venous pressure detected on visual inspection of the jugular venous pressure or ultrasound assessment of the inferior vena cava or internal jugular veins. Other findings with utility include a dry axilla and dry oral mucosa. With chronic anemia, hemodynamic changes detectable on examination may be minimal, as the body compensates by retaining extracellular volume.

Controversies in the Postoperative Management of the Critically Ill Heart Transplant Patient

Heart transplant recipients are susceptible to a number of complications in the immediate postoperative period. Despite advances in surgical techniques, mechanical circulatory support (MCS), and immunosuppression, evidence supporting optimal management strategies of the critically ill transplant patient is lacking on many fronts. This review identifies some of these controversies with the aim of stimulating further discussion and development into these gray areas.

The pulmonary artery catheter: is it still alive?

PURPOSE OF REVIEW

The present review discusses the current role of the pulmonary artery catheter (PAC) in the hemodynamic monitoring of critically ill patients.

RECENT FINDINGS

The PAC has an important role in the characterization and management of hemodynamic alterations in critically ill patients. Use of the PAC has decreased in the last 30 years because of recent advances in less invasive hemodynamic monitoring techniques, in particular transpulmonary thermodilution and echocardiography, combined with the publication of the results of several randomized trials that failed to show improvements in outcome with the use of the PAC in various settings. Although it is obvious that the PAC should not be used in most critically ill patients, the PAC is still indicated in some patients with circulatory and/or respiratory failure, especially when associated with pulmonary hypertension or left heart dysfunction. As for any technique, optimal PAC use requires expertise in insertion, acquisition, and interpretation of measurements. The decrease in use of the PAC may unfortunately limit exposure of junior doctors and nurses to this device, so that they become less familiar with using the PAC, making it more complicated and less optimal.

SUMMARY

The PAC still has an important role in the cardiopulmonary monitoring of critically ill patients.

Survey of Intensive Care Nurses’ Knowledge Relating to the Pulmonary Artery Catheter

In 2003 there was an increase in the use of pulmonary artery catheters in Australia from 12,000 to 16,000 units in intensive care and peri-operative care. This survey of intensive care nurses in five intensive care units in Queensland addressed knowledge of use, safety and complications of the pulmonary artery catheter, using a previously validated 31 question multiple choice survey.

One hundred and thirty-nine questionnaires were completed, a response rate of 46%. The mean score was 13.3, standard deviation ±4.2 out of a total of 31 (42.8% correct). The range was 4 to 25. Scores were significantly higher in those participants with more ICU experience, higher nursing grade, a higher self-assessed level of knowledge and greater frequency of PAC supervision. There was no significant correlation between total score and hospital- or university-based education, or total score and public or private hospital participants. Fifty-one per cent were unable to correctly identify the significant pressure change as the catheter is advanced from the right ventricle to the pulmonary artery.

Hemodynamics of Cardiogenic Shock

Cardiogenic shock (CS) represents an advanced state of morbidity along the pathophysiologic pathway of end-organ hypoperfusion caused by reduced cardiac output and blood pressure. Acute coronary syndromes remain the most common cause of CS. The spectrum of hypoperfusion states caused by low cardiac output ranges from pre-CS to refractory CS and can be characterized by an array of hemodynamic parameters. This review provides the foundation for a hemodynamic understanding of CS including the use of hemodynamic monitoring for diagnosis and treatment, the cardiac and vascular determinants of CS, and a hemodynamic approach to risk stratification and management of CS.

Pulmonary artery catheter use in adult patients undergoing cardiac surgery: a retrospective, cohort study

Background

The utility of pulmonary artery catheters (PACs) and their measurements depend on a variety of factors including data interpretation and personnel training. This US multi-center, retrospective electronic health record (EHR) database analysis was performed to identify associations between PAC use in adult cardiac surgeries and effects on subsequent clinical outcomes.

Methods

This cohort analysis utilized the Cerner Health Facts database to examine patients undergoing isolated coronary artery bypass graft (CABG), isolated valve surgery, aortic surgery, other complex non-valvular and multi-cardiac procedures, and/or heart transplant from January 1, 2011, to June 30, 2015. A total of 6844 adults in two cohorts, each with 3422 patients who underwent a qualifying cardiac procedure with or without the use of a PAC for monitoring purposes, were included. Patients were matched 1:1 using a propensity score based upon the date and type of surgery, hospital demographics, modified European System for Cardiac Operative Risk Evaluation (EuroSCORE II), and patient characteristics. Primary outcomes of 30-day in-hospital mortality, length of stay, cardiopulmonary morbidity, and infectious morbidity were analyzed after risk adjustment for acute physiology score.

Results

There was no difference in the 30-day in-hospital mortality rate between treatment groups (OR, 1.17; 95% CI, 0.65-2.10; p = 0.516). PAC use was associated with a decreased length of stay (9.39 days without a PAC vs. 8.56 days with PAC; p < 0.001), a decreased cardiopulmonary morbidity (OR, 0.87; 95% CI, 0.79-0.96; p < 0.001), and an increased infectious morbidity (OR, 1.28; 95% CI, 1.10-1.49; p < 0.001).

Conclusions

Use of a PAC during adult cardiac surgery is associated with decreased length of stay, reduced cardiopulmonary morbidity, and increased infectious morbidity but no increase in the 30-day in-hospital mortality. This suggests an overall potential benefit associated with PAC-based monitoring in this population.

Trial registration

The study was registered at clinicaltrials.gov (NCT02964026) on November 15, 2016.

Three-Dimensional Inferior Vena Cava for Assessing Central Venous Pressure in Patients with Cardiogenic Shock

BACKGROUND

The inferior vena cava (IVC) has a complex three-dimensional (3D) shape, but measurements used to estimate central venous pressure (CVP) remain based on two-dimensional (2D) echocardiographic imaging. The aim of this study was to investigate the accuracy of IVC size and collapsibility index obtained by 3D echocardiography for assessing CVP in patients with cardiogenic shock.

METHODS

Eighty consecutive echocardiographic examinations performed in 33 patients (mean age, 72 ± 15 years; mean left ventricular ejection fraction, 19 ± 10%) admitted for cardiogenic shock were prospectively included. Two-dimensional and 3D images of the IVC were acquired simultaneously with invasive measurement of CVP, both at rest and during a sniff test. IVC diameters, 3D IVC area, and IVC collapsibility index (IVCCI) were assessed. The eccentricity index was computed from 3D data as the ratio of maximum to minimum IVC diameter. A cutoff value of 10 mm Hg for CVP defined patients with euvolemic hemodynamic status.

RESULTS

At rest, IVC diameter averaged 23 ± 7 mm by 2D imaging and 25 ± 8 × 19 ± 7 mm by 3D imaging. The IVC had an eccentric shape (eccentricity index = 1.3) that increased when CVP was ≤10 mm Hg and during the sniff test (P < .001). IVC measurements by 2D and 3D imaging were correlated with CVP. The best correlation was obtained with IVCCI derived from 2D diameters (R = -0.69) and 3D areas (R = -0.82). Using a cutoff value of 50% for IVCCI, 11 examinations were misclassified by 2D imaging and only one by 3D imaging. Inter- and intraobserver reproducibility for IVC area was 7 ± 6% and 5 ± 3%, respectively.

CONCLUSIONS

In patients with cardiogenic shock, IVCCI from area by 3D echocardiography is reproducible and accurate to evaluate CVP.

Clinical examination for diagnosing circulatory shock

PURPOSE OF REVIEW

In the acute setting of circulatory shock, physicians largely depend on clinical examination and basic laboratory values. The daily use of clinical examination for diagnostic purposes contrasts sharp with the limited number of studies. We aim to provide an overview of the diagnostic accuracy of clinical examination in estimating circulatory shock reflected by an inadequate cardiac output (CO).

RECENT FINDINGS

Recent studies showed poor correlations between CO and mottling, capillary refill time or central-to-peripheral temperature gradients in univariable analyses. The accuracy of physicians to perform an educated guess of CO based on clinical examination lies around 50% and the accuracy for recognizing a low CO is similar. Studies that used predefined clinical profiles composed of several clinical examination signs show more reliable estimations of CO with accuracies ranging from 81 up to 100%.

SUMMARY

Single variables obtained by clinical examination should not be used when estimating CO. Physician's educated guesses of CO based on unstructured clinical examination are like the 'flip of a coin'. Structured clinical examination based on combined clinical signs shows the best accuracy. Future studies should focus on using a combination of signs in an unselected population, eventually to educate physicians in estimating CO by using predefined clinical profiles.

Postoperative hemodynamic instability and monitoring

PURPOSE OF REVIEW

The purpose of the review is to identify the recently validated minimally invasive or noninvasive monitoring devices used to both monitor and guide resuscitation in the critically ill patients.

RECENT FINDINGS

Recent advances in noninvasive measures of blood pressure, blood flow, and vascular tone have been validated and complement existing minimally invasive and invasive monitoring techniques. These monitoring approaches should be used within the context of a focused physical examination and static vital sign analysis. When available, measurement of urinary output is often included. All studies show that minimally invasive and noninvasive measure of arterial pressure and cardiac output are possible and often remain as accurate as invasive measures. The noninvasive techniques degrade in severe circulatory failure and the use of vasopressor therapy. Importantly, these output parameters form the treatment goals for many goal-directed therapies protocols.

SUMMARY

When coupled with a focused physical examination and functional hemodynamic monitoring analyses, these measures become even more specific at defining volume responsiveness and vasomotor tone and can be used to drive resuscitation strategies.

Usefulness of ultrasonographic measurement of the diameter of the inferior vena cava to predict responsiveness to intravascular fluid administration in patients with cancer

We conducted an observational, longitudinal prospective study in which we measured the diameters of the inferior vena cava (IVC) of 47 patients using ultrasonography. The aim of our study was to assess the state of blood volume and to determine the percentage of patients who responded to intravascular volume expansion. Only 17 patients (36%) responded to fluid management. A higher number of responding patients had cardiovascular failure compared with nonresponders (82% vs. 50%, P = 0.03). Among the patients with cardiovascular failure, the probability of finding responders was 4.6 times higher than that of not finding responders (odds ratio, 4.66; 95% confidence interval, 1.10-19.6; P = 0.04). No significant difference was observed in the mortality rate between the two groups (11% vs. 23%, P = 0.46). In conclusion, responding to intravascular volume expansion had no impact on patient survival in the intensive care unit.

Stroke Volume Monitoring: Novel Continuous Wave Doppler Parameters, Algorithms and Advanced Noninvasive Haemodynamic Concepts

PURPOSE OF REVIEW

Adequate oxygen delivery is essential for life, with hypoxia resulting in dysfunction, and ultimately death, of the cells, organs and organism. Blood flow delivers the oxygen bound in the blood, while haemodynamics is the science of blood flow. Stroke volume (SV) is the fundamental unit of blood flow, and reflects the interdependent performance of the heart, the vessels and the autonomic nervous system. However, haemodynamic management remains generally poor and predominantly guided by simple blood pressure observations alone.

RECENT FINDINGS

Doppler ultrasound measures SV with unequalled clinical precision when operated by trained personnel. Combining SV with BP measurements allows calculation of flow-pressure based measures which better reflect cardiovascular performance and allows personalised physiologic and pathophysiologic modelling consistent with Frank's and Starling's observations.

SUMMARY

Doppler SV monitoring and novel flow-pressure parameters may improve our understanding of the cardiovascular system and lead to improved diagnosis and therapy. This review examines the physics and practice of Doppler SV monitoring and its application in advanced haemodynamics.

Impact of the Royal Australasian College of Physicians' clinical examination preparation on basic physician trainee assessment of jugular venous pressure

Australian internal medicine trainees undergo intensive training in preparation for the Royal Australasian College of Physicians (RACP) clinical examination. Trainees preparing for the 2013 RACP clinical examination assessed the jugular venous pressure (JVP) of patients, with central venous pressure monitoring in the intensive care unit before and after the exam. RACP clinical examination preparation was associated with improvements of trainees' ability to identify JVP that were not elevated, although the JVP examination was performed marginally as a diagnostic test. Ongoing training might further improve this skill.

Point-of-Care Ultrasound for Jugular Venous Pressure Assessment: Live and Online Learning Compared

Introduction

Point-of-care ultrasound (POCUS) is a novel technique for the assessment of jugular venous pressure. Distance education may allow for efficient dissemination of this technique. We compared online learning to a live course for teaching ultrasonography jugular venous pressure (u-JVP) to determine if these teaching methods yielded different levels of comfort with and use of u-JVP.

Methods

This was an interventional trial of Canadian emergency physicians who had taken a basic POCUS course. The participants were in one of three Groups: online learning (Group OL), live teaching (Group LT), control (Group C). Group LT participants also took an advanced course prior to the study that included instruction in u-JVP. The participants who took the basic course were randomized to Group OL or Group C. Group OL was subject to the intervention, online learning. Group C only received an article citation regarding u-JVP. Questionnaires were completed before and after the intervention. The primary outcome was physician self-reported use and comfort with the technique of u-JVP after online learning compared to live teaching.

Results

Of the 287 advanced course participants, 42 completed the questionnaires (Group LT). Of the 3303 basic course participants, 47 who were assigned to Group OL completed the questionnaires and 47 from Group C completed the questionnaires. Use of u-JVP increased significantly in Group OL (from 15% to 55%) and Group C (from 21% to 47%) with the intervention. The comfort with use did not differ between Group LT and Group OL (p=0.14). The frequency of use remained higher in Group LT than Group OL (p=0.07).

Conclusion

Online learning increases the use and comfort with performing u-JVP for emergency physicians with prior POCUS experience. Although the comfort with use of u-JVP was similar in Groups LT and OL, online learning appears to yield levels of use that are less than those of a live course.

Usefulness of Serial Measurements of Inferior Vena Cava Diameter by VscanTM to Identify Patients With Heart Failure at High Risk of Hospitalization

Estimation of volume status is integral to heart failure (HF) management. Measurement of inferior vena cava (IVC) diameter (IVCd) by ultrasound provides a noninvasive estimate of right atrial pressures. The GE Vscan is a handheld ultrasound (HHU) device that allows for point-of-care measurements to assess volume status. We hypothesize that IVCd measurements using HHU can predict the risk of HF admission. We retrospectively analyzed a cohort of patients with HF treated in an ambulatory care setting over 17 months. Serial measurements of IVCd were obtained using HHU in the supine position from the subcostal window. Log-binomial regression models were used to compare IVCd measurements between patients with and without HF admissions and to estimate the association between IVCd and risk of HF admission. Of the 355 patients with systolic (38%) and diastolic HF (62%) who were analyzed, 45% were women with a mean age of 73 years at the time of the first IVCd measurement. Overall, 3,488 measurements were obtained, and 32.4% of patients were hospitalized during follow-up. Patients with at least 1 hospital admission had a greater mean IVCd than those who were not admitted (2.0 vs 1.8 cm, p <0.01). In our analysis, every 0.5-cm increase in the mean IVCd was associated with a 38% increase in risk of HF admission (risk ratio [RR] 1.38, 95% CI 1.16 to 1.62, p <0.01). The risk of HF admission was also significantly increased in patients with IVCd 2.0 to 2.49 cm (RR 1.79, 95% CI 1.27 to 2.52, p <0.01) and ≥2.5 cm (RR 2.39, 95% CI 1.55 to 3.67, p <0.01), compared with patients with an IVCd < 2.0 cm. Increasing IVCd as measured by HHU at the point-of-care is associated with an increased risk of HF admission and may provide clinically useful information at the point-of-care to guide HF management.

The Routine Use of the Pulmonary Artery Catheter Should Be Abandoned

The pulmonary artery catheter (PAC) is the most common method of measuring cardiac output in cardiac surgery. However, its use has always been questioned in terms of survival benefit, specifically with regard to the accuracy of its measurements and its invasive nature, with the potential for serious complications. In this review we aimed to develop a clear understanding of the pitfalls of the use of PAC, and discuss its risks and available alternatives. We conclude that there is no indication for the routine use of PAC such that clinicians should carefully consider the clinical risks and benefits on a patient by patient basis.

Management of the Low Cardiac Output Syndrome Following Surgery for Congenital Heart Disease

The purpose of this review is to discuss the management of the low cardiac output syndrome (LCOS) following surgery for congenital heart disease. The LCOS is a well-recognized, frequent post-operative complication with an accepted collection of hemodynamic and physiologic aberrations. Approximately 25% of children experience a decrease in cardiac index of less than 2 L/min/m2 within 6-18 hours after cardiac surgery. Post-operative strategies that may be used to manage patients as risk for or in a state of low cardiac output include the use of hemodynamic monitoring, enabling a timely and accurate assessment of cardiovascular function and tissue oxygenation; optimization of ventricular loading conditions; the judicious use of inotropic agents; an appreciation of and the utilization of positive pressure ventilation for circulatory support; and, in some circumstances, mechanical circulatory support. All interventions and strategies should culminate in improving the relationship between oxygen supply and demand, ensuring adequate tissue oxygenation.

Hemodynamic Monitoring in the Acute Management of Pediatric Heart Failure

One of the basic tenets of cardiac critical care is to ensure adequate tissue oxygenation. As with other critical illness such as trauma and acute myocardial infarction studies have demonstrated that making the right diagnosis at the right time improves outcomes. The same is true for the management of patients at risk for or in a state of shock. In order to optimize outcomes an accurate and timely assessment of cardiac function, cardiac output and tissue oxygenation must be made. This review discusses the limitations of the standard assessment of cardiovascular function, and adjunctive monitoring modalities that may be used to enhance the accuracy and timely implementation of therapeutic strategies to improve tissue oxygenation.

The Pulmonary Artery Catheter in Anesthesia Practice in 2007: An Historical Overview With Emphasis on the Past 6 Years

The pulmonary artery catheter has been widely used in anesthesiology and critical care medicine. Until recently, only retrospective or relatively weak prospective studies examining its effect on outcome had been performed. Over the past 6 years, however, a number of well-designed prospective trials and statistically sound retrospective studies have been completed. All of these show no benefit and some even reveal a potential for increased morbidity. Reasons for this device's inability to improve outcome are numerous, including wrong patient selection and misinterpretation, but the most impressive and convincing evidence is that filling pressures measured from the catheter, particularly the pulmonary artery “wedge” pressure, have no physiologic value. The wedge pressure has been shown to not correlate with other accepted methods of determining left ventricular filling or volume or intravascular volume and also does not help to generate cardiac function curves. Therefore, knowledge of it may actually lead to incorrect management more frequently than not.

Hemodynamic Monitoring

OBJECTIVES

In this review, we discuss hemodynamic monitoring modalities, including their application, the interpretation of data, limitations, and impact on outcomes.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSIONS

One of the tenets of critical care medicine is to ensure adequate tissue oxygenation. This assessment must be timely and accurate to optimize outcomes. The clinical assessment of cardiac function, cardiac output, and tissue oxygenation based on the physical examination and standard hemodynamic variables, although an indispensable part of this exercise, has significant limitations. The use of adjunctive hemodynamic monitoring modalities provides a much more objective, accurate, and timely assessment of the patient's hemodynamic profile and is invaluable for assessing the patient's clinical status, clinical trajectory, and response to interventions.

The Diagnostic and Therapeutic Impact of Point-of-Care Ultrasonography in the Intensive Care Unit

PURPOSE

In light of point-of-care ultrasonography's (POCUS) recent rise in popularity, assessment of its impact on diagnosis and treatment in the intensive care unit (ICU) is of key importance.

METHODS

Ultrasound examinations were collected through an ultrasound reporting software in 6 multidisciplinary ICU units from 3 university hospitals in Canada and the United States. This database included a self-reporting questionnaire to assess the impact of the ultrasound findings on diagnosis and treatment. We retrieved the results of these questionnaires and analyzed them in relation to which organs were assessed during the ultrasound examination.

RESULTS

One thousand two hundred and fifteen ultrasound studies were performed on 968 patients. Intensivists considered the image quality of cardiac ultrasound to be adequate in 94.7% compared to 99.7% for general ultrasound ( P < .001). The median duration of a cardiac examination was 10 (interquartile range [IQR] 10) minutes compared to 5 (IQR 8) minutes for a general examination ( P < .001). Overall, ultrasound findings led to a change in diagnosis in 302 studies (24.9%) and to a change in management in 534 studies (44.0%). A change in diagnosis or management was reported more frequently for cardiac ultrasound than for general ultrasound (108 [37.1%] vs 127 [16.5%], P < .001) and (170 [58.4%] vs 270 [35.1%], P < .001). Assessment of the inferior vena cava for fluid status emerged as the critical care ultrasound application associated with the greatest impact on management.

CONCLUSION

Point-of-care ultrasonography has the potential to optimize care of the critically ill patients when added to the clinical armamentarium of the intensive care physician.

Analytic Reviews : Organ Procurement and Brain Death in Trauma Patients

The success rates and effectiveness of transplantation programs continue to increase, as does the need for cadaveric organs. Increasing organ procurement is a worthwhile goal that can be fully justified on economic, humanistic, and ethical bases. Although a great deal of progress has been made in terms of public and political awareness of organ procurement problems, additional changes and further education will be necessary before the number of cadaveric organs that are needlessly wasted can be reduced.

Management of patients with unsurvivable head in juries or patients who are candidates for organ donation is a complex task involving critical care management, the declaration of brain death, and the identification of, and request for, organ donation from next of kin. This process involves the coordinated efforts of neurosur geons, critical care specialists, social workers, and the transplant team coordinators in organ procurement pro grams. Patients are best managed in tertiary centers that have staffs with the expertise and interest in performing these tasks. The time to cardiac death in brain-dead pa tients is frequently short and is hastened by the develop ment of rapidly progressive derangements in gas ex change, fluid and electrolyte homeostasis, temperature regulation, coagulation, and cardiovascular function. Premature death under these circumstances continues to be a major reason for organ-procurement failure. Ag gressive monitoring and treatment of the multiple med ical problems encountered, however, may reduce the number of patients who die prematurely and thus in crease organ procurement rates.

Pulmonary Artery Catheters: An Update

Pulmonary artery (PA) catheters are widely used in the care of the critically ill. Numerous catheter designs are available, and the list of indications for their use is con stantly expanding. Extensive physiological data are sup plied by catheters. Right atrial, right ventricular, PA, and PA wedge pressure waveforms, as well as cardiac output and several derived parameters (e.g., systemic vascular resistance, pulmonary vascular resistance) are easily measured. Clinical application of these data may aid in diagnosis and management of acutely ill patients. Physi cians using catheters need to be aware of the numerous complications associated with their use. Scrupulous at tention to insertion and maintenance techniques will minimize the incidence of many of these complications. The undefined risk/benefit ratio of PA catheterization has caused controversy among physicians. Prospective studies to define better the risks versus benefits of PA catheters are currently being planned. Physicians using PA catheters should recognize that the catheters have no direct therapeutic benefit and that PA catheterization should neither replace bedside clinical evaluation nor delay treatment of the patient.

Analytic Reviews : Radiological Assessment of Central Vascular Volume Status in an Intensive Care Unit Setting

We studied the chest radiographs of 126 patients under going pulmonary artery catheterization. An experienced radiologist, unaware of the patient's clinical condition and results of pulmonary artery catheterization and without review of prior films, evaluated each radiograph focusing exclusively on fluid status, and assigned each one to one of the following four categories: definitely or probably elevated central vascular volume status, or definitely or probably nonelevated central vascular vol ume status. This assessment was then compared with the "official" reading, performed with knowledge of the patient's clinical status and with availability of previous chest radiographs. The radiologist's prediction was more accurate than the official report (65% proportion of correct classification vs. 59% ) ( p < 0.05). Patients with actual high pulmonary artery wedge pressure read ings were more difficult to diagnose correctly than pa tients with low or normal pulmonary artery wedge pres sure. In those patients in whom the radiologist felt more confident of his prediction (25% of patients), diagnostic accuracy improved considerably for both the high and normal pulmonary artery wedge pressure groups of pa tients to a proportion of correct classification of 71% and 80%, respectively. Although the radiological assess ment was not accurate enough to replace pulmonary artery catheterization, the official reading can be im proved by focusing on specific radiological features to estimate central vascular volume status.

Continuing Care of Multiorgan Donor Patients

Preserving the optimal function of donor organs must be the primary goal of physicians caring for patients who have been certified brain dead and from whom organs will be transplanted. During the hours before organ removal, several significant medical challenges may emerge. These challenges include restoration and maintenance of intravascular volume and cardiac output to assure adequate oxygen delivery to donor tissue; re suscitation of the patient from spontaneous cardiac ar rest ; evaluation and reversal of polyuria; management of poikilothermia and the effects of hypothermia; and treat ment of hypopituitarism and other possible changes in circulating hormones. Individual organ function and the interdependency among donor organs must be carefully monitored and balanced to assure that the recipient re ceives organs that have the best opportunity for optimal primary function. Care of the multiorgan brain dead pa tient and his or her family requires a multidisciplinary team skilled not only in the medical and surgical aspects of transplantation but also in the care of families who have suffered loss.

A new focus for patient care is appropriate after the decision has been made that a patient is brain dead and will become an organ donor. Because preser vation of brain function is no longer possible, treat ment priorities should shift to maximize perfusion and function of the donor organs. Through careful management of the donor patient, the recipient will receive organs that are less likely to undergo pri mary failure. This discussion will review the physio logical support necessary to sustain brain dead pa tients and to optimize donor organ function until organ removal is completed. It is assumed that indi vidual organs will be assessed and accepted or re jected for donation using criteria established by lo cal organ procurement teams. Such criteria will not be discussed here.

The brain dead organ donor presents a variety of management challenges (Table 1) that may extend over many hours while members of transplant teams and organ recipients are assembled and tis sue testing is completed. The responsibility for care may remain with the admitting physician or critical care medicine specialists, or it may be transferred to the transplant service. Coordination, however, remains the key to a successful outcome. The avail ability and interest of a knowledgeable physician to supervise the donor patient's care continues to be crucial because a variety of problems, each capable of rendering donor organs useless, may develop in the hours between brain death and organ removal.

Analytic Reviews : Hemodynamic Management of the Adult Respiratory Distress Syndrome

Hemodynamic management is an essential aspect of the care of patients with adult respiratory distress syn drome (ARDS). On the basis of current knowledge, our proposed goals of management are to maximize pe ripheral oxygen delivery while attempting to minimize further lung damage or dysfunction. The major patho physiologic abnormalities of ARDS are an increased lung vascular permeability, right-to-left intrapulmonary shunting, and pulmonary vascular resistance. These abnormalities must be understood to select the proper therapy. Although all patients with ARDS share these abnormalities, they differ in their associated clinical conditions and underlying cardiovascular status. Be cause each ARDS patient may respond differently to therapy, hemodynamic management must be selected empirically with the goal of therapy as a guide. We have considered available therapeutic options including posi tive end-expiratory pressure, volume depletion, volume expansion, vasopressors, and vasodilators. In the future hemodynamic management of patients with ARDS will likely change as better methods of patient assessment and treatment are developed.

Pediatric Bone Marrow Transplantation: Intensive Care Management

Bone marrow transplantation (BMT) has assumed in creasing importance in the treatment of bone marrow failure, hematopoietic malignancies, congenital immuno deficiencies, and solid tumors. Children undergoing BMT are at high risk for infection and hemorrhage dur ing the period of aplasia. In addition, life-threatening complications of circulatory, pulmonary, gastrointesti nal, hepatic, and renal function are common and fre quently require intensive supportive care. This review provides an overview of pediatric BMT that focuses on management problems relevant to intensive care. Thor ough pretransplantation assessment of underlying organ dysfunction is mandatory before undertaking BMT. The complications associated with preconditioning regi mens that use total body irradiation and high doses of ablative chemotherapy are described. Finally, problems involving individual organs are discussed by systems. The challenge of improving the results of BMT in the treatment of childhood malignant and hematopoietic disorders depends, in large part, on successful preven tive measures and good management of complications that occur immediately before and within the first 100 days after transplantation. As BMT is indicated for treat ment of an increasing number of diseases, more patients will require the care of intensivists familiar with trans plantation-related complications.

Noninvasive cardiac output estimation by inert gas rebreathing in pediatric and congenital heart disease

BACKGROUND

Inert gas rebreathing (IGR) techniques provide rapid, reliable estimates of cardiac output in adults with structurally normal hearts. Data on IGR reliability in pediatric and congenital heart disease populations are lacking. Our objective was to validate pulmonary blood flow (Qp) measurement by IGR compared with clinical reference tests, cardiovascular magnetic resonance (CMR), and indirect Fick.

METHODS

Pulmonary blood flow was measured by IGR and CMR or indirect Fick in 80 patients grouped by presence and type of shunt lesion. Inert gas rebreathing precision was assessed using Bland-Altman analysis, repeatability coefficient, intraclass correlation, and coefficient of error. Agreement with the reference tests was assessed with Bland-Altman plots. For comparison, agreement between the 2 reference tests, CMR and indirect Fick, was assessed in 34 contemporary patients.

RESULTS

Subjects were aged 7-78 years and had a wide range of cardiac diagnoses. Inert gas rebreathing Qp showed good repeatability (95% limits of agreement for 2 trials = ±22%, repeatability coefficient = 1.2 L/min, intraclass correlation = 0.92, and coefficient of error = 5%). In the absence of left-to-right shunting (n = 67), IGR Qp estimates agreed with CMR and indirect Fick Qp estimates, and the reference tests agreed with each other, with mean bias ≤10% (≤0.5 L/min) and 95% limits of agreement ±33%-38%. Conversely, IGR was unreliable in patients with left-to-right shunt (n = 14), with large bias (-58%, -4.0 L/min) and wide limits of agreement (±76%).

CONCLUSIONS

Inert gas rebreathing reliably estimates Qp in children and adults with congenital heart disease in the absence of left-to-right shunting, with agreement comparable to that seen between CMR and indirect Fick estimates.

Hemodynamic monitoring in the intensive care unit: a Brazilian perspective

OBJECTIVE

In Brazil, there are no data on the preferences of intensivists regarding hemodynamic monitoring methods. The present study aimed to identify the methods used by national intensivists, the hemodynamic variables they consider important, the regional differences, the reasons for choosing a particular method, and the use of protocols and continued training.

METHODS

National intensivists were invited to answer an electronic questionnaire during three intensive care events and later, through the Associação de Medicina Intensiva Brasileira portal, between March and October 2009. Demographic data and aspects related to the respondent preferences regarding hemodynamic monitoring were researched.

RESULTS

In total, 211 professionals answered the questionnaire. Private hospitals showed higher availability of resources for hemodynamic monitoring than did public institutions. The pulmonary artery catheter was considered the most trusted by 56.9% of the respondents, followed by echocardiograms, at 22.3%. Cardiac output was considered the most important variable. Other variables also considered relevant were mixed/central venous oxygen saturation, pulmonary artery occlusion pressure, and right ventricular end-diastolic volume. Echocardiography was the most used method (64.5%), followed by pulmonary artery catheter (49.3%). Only half of respondents used treatment protocols, and 25% worked in continuing education programs in hemodynamic monitoring.

CONCLUSION

Hemodynamic monitoring has a greater availability in intensive care units of private institutions in Brazil. Echocardiography was the most used monitoring method, but the pulmonary artery catheter remains the most reliable. The implementation of treatment protocols and continuing education programs in hemodynamic monitoring in Brazil is still insufficient.

Defining normal jugular venous pressure with ultrasonography

Objective:

Determination of jugular venous pressure (JVP) by physical examination (E-JVP) is unreliable. Measurement of JVP with ultrasonography (U-JVP) is easy to perform, but the normal range is unknown. The objective of this study was to determine the normal range for U-JVP.

Methods:

We conducted a prospective anatomic study on a convenience sample of emergency department (ED) patients over 35 years of age. We excluded patients who had findings on history or physical examination suggesting an alteration of JVP. With the head of the bed at 45°, we determined the point at which the diameter of the internal jugular vein (IJV) began to decrease on ultrasonography (“the taper”). Research assistants used 2 techniques to measure U-JVP in all participants: by measuring the vertical height (in centimetres) of the taper above the sternal angle, and adding 5 cm; and by recording the quadrant in the IJV's path from the clavicle to the angle of the jaw in which the taper was located. To determine interrater reliability, separate examiners measured the U-JVP of 15 participants.

Results:

We successfully determined the U-JVP of all 77 participants (38 male and 39 female). The mean U-JVP was 6.35 (95% confidence interval 6.11–6.59) cm. In 76 participants (98.7%), the taper was located in the first quadrant. Determination of interrater reliability found κ values of 1.00 and 0.87 for techniques 1 and 2, respectively.

Conclusion:

The normal U-JVP is 6.35 cm, a value that is slightly lower than the published normal E-JVP. Interrater reliability for U-JVP is excellent. The top of the IJV column is located less than 25% of the distance from the clavicle to the angle of the jaw in the majority of healthy adults. Our findings suggest that U-JVP provides the potential to reincorporate reliable JVP measurement into clinical assessment in the ED. However, further research in this area is warranted.

Arterial lines in the ICU: a call for rigorous controlled trials

The appropriate justification for using a diagnostic or therapeutic intervention is that it provides benefit to patients, society, or both. For decades, indwelling arterial catheters have been used very commonly in patients in the ICU, despite a complete absence of data addressing whether they confer any such benefits. Both of the main uses of arterial catheters, BP monitoring and blood sampling for laboratory testing, can be done without these invasive devices. Prominent among complications of arterial catheters are bloodstream infections and arterial thrombosis. To my knowledge, only a single observational study has assessed a patient-centered outcome related to arterial catheter use, and it found no evidence that they reduce hospital mortality in any patient subgroup. Given the potential dangers, widespread use, and uncertainty about consequences of arterial catheter use in ICUs, equipoise exists and randomized trials are needed. Multiple studies in different, well-characterized, patient subgroups are needed to clarify whether arterial catheters influence outcomes. These studies should assess the range of relevant outcomes, including mortality, medical resource use, patient comfort, complications, and costs.

Point-of-care cardiac ultrasound in acute medicine--the quick scan

The optimum management of acute medical patients requires prompt and accurate diagnosis, monitoring and treatment. The clinical history and physical examination remain central to diagnosis, but often need supplementation by laboratory testing or imaging. Echocardiographic assessment of cardiac structure and function provides valuable information that can aid diagnosis and assess clinical progress. It has many advantages as an imaging modality, and recent technological advances have resulted in hand-held, battery-powered ultrasound devices that provide high-quality images. Three broad applications of cardiac ultrasound now exist: conventional echocardiography, focussed echocardiography and the quick-scan. A quick-scan using a hand-held ultrasound device is readily integrated into the bedside clinical assessment, providing information that can be used immediately in diagnostic reasoning; it can also guide pericardiocentesis. Hand-held ultrasound devices can also be used in acute situations, as well as geographically remote areas or special situations (eg disaster zones) where other imaging is not available. However, the diagnostic yield of echocardiography is user dependent, and training is required for its benefits to be realised, adding to the hardware costs. More data are needed on the incremental value of hand-held ultrasonography and a quick-scan over conventional methods of assessment, their impact on clinical outcomes, and cost effectiveness.

Clinical evaluation compared to the pulse indicator continuous cardiac output system in the hemodynamic assessment of critically ill patients

OBJECTIVE

The objective was to assess the effects of pulse indicator continuous cardiac output catheterization on the management of critically ill patients and the alteration of therapy in intensive care units.

METHODS

One hundred thirty-two patients with primary physiological abnormalities of hypotension or hypoxemia were evaluated. Prior to catheterization, physicians were asked to complete a questionnaire that collected information regarding predictions of the ranges of several hemodynamic variables and plans for therapy. After catheterization, each chart was reviewed by a panel of intensive care attending physicians to determine the possibility of altering the therapy.

RESULTS

Overall correct classification of the key variables ranged from 46.0% to 65.4%. Catheterization results prompted alterations in therapy for 45.5% of patients. The fellows were less accurate in predicting hemodynamic values for patients whose diagnoses were unknown, and the primary abnormality was hypotension. There was significant difference in the physicians' abilities to predict the hemodynamics for the subgroups with and without acute myocardial infarction. When the patients were divided into 3 subgroups by Acute Physiology and Chronic Health Evaluation II and Sepsis-related Organ Failure Assessment scores, the fellows had the most difficulty predicting the variables of the moderately ill patients in the middle subgroup, which led to the greatest percentage of therapy alterations for this subgroup; and this difference was significant.

CONCLUSIONS

The hemodynamic variables obtained from pulse indicator continuous cardiac output catheterization improved the accuracy of bedside evaluations and led to alterations in therapeutic plans, particularly among the moderately ill patients with hypotension or unknown diagnoses.

Obituary: pulmonary artery catheter 1970 to 2013

The birth of the intermittent injectate-based conventional pulmonary artery catheter (fondly nicknamed PAC) was proudly announced in the New England Journal of Medicine in 1970 by his parents HJ Swan and William Ganz. PAC grew rapidly, reaching manhood in 1986 where, in the US, he was shown to influence the management of over 40% of all ICU patients. His reputation, however, was tarnished in 1996 when Connors and colleagues suggested that he harmed patients. This was followed by randomized controlled trials demonstrating he was of little use. Furthermore, reports surfaced suggesting that he was unreliable and inaccurate. It also became clear that he was poorly understood and misinterpreted. Pretty soon after that, a posse of rivals (bedside echocardiography, pulse contour technology) moved into the neighborhood and claimed they could assess cardiac output more easily, less invasively and no less reliably. To make matter worse, dynamic assessment of fluid responsiveness (pulse pressure variation, stroke volume variation and leg raising) made a mockery of his ‘wedge’ pressure. While a handful of die-hard followers continued to promote his mission, the last few years of his existence were spent as a castaway until his death in 2013. His cousin (the continuous cardiac output PAC) continues to eke a living mostly in cardiac surgery patients who need central access anyway. This paper reviews the rise and fall of the conventional PAC.

Monitoring cardiac function: echocardiography, pulse contour analysis and beyond

Haemodynamic monitoring has developed considerably over the last decades, nowadays comprising a wide spectrum of different technologies ranging from invasive to completely non-invasive techniques. At present, the evidence to continuously measure and optimise stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion in the perioperative setting and consequently to improve patients' outcome is substantial. Surprisingly, there is a striking discrepancy between the developments in advanced haemodynamic monitoring combined with evidence-based knowledge on the one hand and daily clinical routine on the other hand. Recent trials have shown that perioperative mortality is higher than anticipated, emphasising the need for the speciality of anaesthesiology to face the problem and to translate proven concepts into clinical routine to improve patients' outcome. One basic principle of these concepts is to monitor and to optimise cardiac function by means of advanced haemodynamic monitoring, using echocardiography, pulse contour analysis and beyond.

Advances in pediatric cardiac intensive care

Pediatric cardiac critical care has made, and continues to make, significant strides in improving outcomes. It is a measure of these successes that much of the discussion in this article does not focus on the reduction of mortality, but rather on perioperative management strategies intended to improve neurologic outcomes. The care of children with critical cardiac disease will continue to rely on broad and collaborative efforts by specialists and primary care practitioners to build on this foundation of success.