The Use of Pulmonary Artery Catheter in Sepsis Patients: A Literature Review

Estimation of Pulmonary Artery Occlusion Pressure Using Doppler Echocardiography in Mechanically Ventilated Patients

OBJECTIVES

Evaluation of left atrial pressure is frequently required for mechanically ventilated critically ill patients. The objective of the present study was to evaluate the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for assessment of the pulmonary artery occlusion pressure (a frequent surrogate of left atrial pressure) in this population.

DESIGN

A pooled analysis of three prospective cohorts of patients simultaneously assessed with a pulmonary artery catheter and echocardiography.

SETTINGS

Medical-surgical intensive care department of two university hospitals in France.

PATIENTS

Mechanically ventilated critically ill patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 98 included patients (males: 67%; mean ± SD age: 59 ± 16; and mean Simplified Acute Physiology Score 2: 54 ± 20), 53 (54%) experienced septic shock. Using the 2016 American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines, the predicted pulmonary artery occlusion pressure was indeterminate in 48 of the 98 patients (49%). Of the 24 patients with an elevated predicted left atrial pressure (grade II/III diastolic dysfunction), only 17 (71%) had a pulmonary artery occlusion pressure greater than or equal to 18 mm Hg. Similarly, 20 of the 26 patients (77%) with a normal predicted left atrial pressure (grade I diastolic dysfunction) had a measured pulmonary artery occlusion pressure less than 18 mm Hg. The sensitivity and specificity of American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines for predicting elevated pulmonary artery occlusion pressure were both 74%. The agreement between echocardiography and the pulmonary artery catheter was moderate (Cohen's Kappa, 0.48; 95% CI, 0.39-0.70). In a proposed alternative algorithm, the best echocardiographic predictors of a normal pulmonary artery occlusion pressure were a lateral e'-wave greater than 8 (for a left ventricular ejection fraction ≥ 45%) or an E/A ratio less than or equal to 1.5 (for a left ventricular ejection fraction < 45%).

CONCLUSIONS

The American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines do not accurately assess pulmonary artery occlusion pressure in ventilated critically ill patients. Simple Doppler measurements gave a similar level of diagnostic performance with less uncertainly.

Early hemodynamic assessment using NICOM in patients at risk of developing Sepsis immediately after emergency department triage

Background

One factor leading to the high mortality rate seen in sepsis is the subtle, dynamic nature of the disease, which can lead to delayed detection and under-resuscitation. This study investigated whether serial hemodynamic parameters obtained from a non-invasive cardiac output monitor (NICOM) predicts disease severity in patients at risk for sepsis.

Methods

Prospective clinical trial of the NICOM device in a convenience sample of adult ED patients at risk for sepsis who did not have obvious organ dysfunction at the time of triage. Hemodynamic data were collected immediately following triage and 2 hours after initial measurement and compared in two outcome groupings: (1) admitted vs. dehydrated, febrile, hypovolemicdischarged patients; (2) infectious vs. non-infectious sources. Receiver operator characteristic (ROC) curves were calculated to determine whether the NICOM values predict hospital admission better than a serum lactate.

Results

50 patients were enrolled, 32 (64 %) were admitted to the hospital. Mean age was 49.5 (± 16.5) years and 62 % were female. There were no significant associations between changes in hemodynamic variables and patient disposition from the ED or diagnosis of infection. Lactate was significantly higher in admitted patients and those with infection (p = 0.01, p = 0.01 respectively). The area under the ROC [95 % Confidence Intervals] for lactate was 0.83 [0.64–0.92] compared to 0.59 [0.41–0.73] for cardiac output (CO), 0.68 [0.49–0.80] for cardiac index (CI), and 0.63 [0.36–0.80] for heart rate (HR) for predicting hospital admission.

Conclusions

CO and CI, obtained at two separate time points, do not help with early disease severity differentiation of patients at risk for severe sepsis. Although mean HR was higher in those patients who were admitted, a serum lactate still served as a better predictor of patient admission from the ED.

PRO: The pulmonary artery catheter has a paramount role in current clinical practice

Ever since its clinical introduction, the utilization of the pulmonary artery catheter (PAC) has been surrounded by multiple controversies, mostly related to imprecise clinical indications and the complications derived from its placement. Currently, one of the most important criticisms of the PAC is the ambiguity in the interpretation of its hemodynamic measurements and therefore, in the translation of this data into specific therapeutic interventions. The popularity of the PAC stems from the fact that it provides hemodynamic data that cannot be obtained from clinical examination. The assumption is that this information would allow better understanding of the individual's hemodynamic profile which would trigger therapeutic interventions that improve patient outcomes. Nevertheless, even with the current diversity of hemodynamic devices available, the PAC remains a valuable tool in a wide variety of clinical settings. The authors present a review exposing the benefits of the PAC, current clinical recommendations for its use, mortality and survival profile, its role in goal-directed therapy, and other applications of the PAC beyond cardiac surgery and the intensive care unit.

Echo is a good, not perfect, measure of cardiac output in critically ill surgical patients

BACKGROUND

Compared with a pulmonary artery catheter (PAC), transthoracic echocardiography (TTE) has been shown to have good agreement in cardiac output (CO) measurement in nonsurgical populations. Our hypothesis is that the feasibility and accuracy of CO measured by TTE (CO-TTE), relative to CO measured by PAC thermodilution (CO-PAC), is different in surgical intensive care unit patients (SP) and nonsurgical patients (NSP).

METHODS

Surgical patients with PAC for hemodynamic monitoring and NSP undergoing right heart catheterization were prospectively enrolled. Cardiac output was measured by CO-PAC and CO-TTE. Pearson coefficients were used to assess correlation. Bland-Altman analysis was used to determine agreement.

RESULTS

Over 18 months, 84 patients were enrolled (51 SP, 33 NSP). Cardiac output TTE could be measured in 65% (33/51) of SP versus 79% (26/33) of NSP; p = 0.17. Inability to measure the left ventricular outflow tract diameter was the primary reason for failure in both groups; 94% (17/18) in SP versus 86% (6/7) NSP; p = 0.47. Velocity time integral could be measured in all patients. In both groups, correlation between PAC and TTE measurement was strong; SP (r = 0.76; p < 0.0001), NSP (r = 0.86; p < 0.0001). Bland-Altman analysis demonstrated bias of -0.1 L/min, limits of agreement of -2.5 and +2.3 L/min, percentage error (PE) of 40% for SP, and bias of +0.4 L/min, limits of agreement of -1.8 and +2.5 L/min, and PE of 40% for NSP.

CONCLUSION

There was strong correlation and moderate agreement between TTE and PAC in both SP and NSP. In both patient populations, inability to measure the left ventricular outflow tract diameter was a limiting factor.

LEVEL OF EVIDENCE

Diagnostic tests or criteria, level III.

Accuracy of Ultrasonographic Measurements of Inferior Vena Cava to Determine Fluid Responsiveness: A Systematic Review and Meta-Analysis

OBJECTIVE

Fluid responsiveness is the ability to increase the cardiac output in response to a fluid challenge. Only about 50% of patients receiving fluid resuscitation for acute circulatory failure increase their stroke volume, but the other 50% may worsen their outcome. Therefore, predicting fluid responsiveness is needed. In this purpose, in recent years, the assessment of the inferior vena cava (IVC) through ultrasound (US) has become very popular. The aim of our work was to systematically review all the previously published studies assessing the accuracy of the diameter of IVC or its respiratory variations measured through US in predicting fluid responsiveness.

DATA SOURCES

We searched in the MEDLINE (PubMed), Embase, Web of Science databases for all relevant articles from inception to September 2017.

STUDY SELECTION

Included articles specifically addressed the accuracy of IVC diameter or its respiratory variations assessed by US in predicting the fluid responsiveness in critically ill ventilated or not, adult or pediatric patients.

DATA EXTRACTION

We included 26 studies that investigated the role of the caval index (IVC collapsibility or distensibility) and 5 studies on IVC diameter.

DATA SYNTHESIS

We conducted a meta-analysis for caval index with 20 studies: The pooled area under the curve, logarithmic diagnostic odds ratio, sensitivity, and specificity were 0.71 (95% confidence interval [CI]: 0.46-0.83), 2.02 (95% CI: 1.29-2.89), 0.71 (95% CI: 0.62-0.80), and 0.75 (95% CI: 0.64-0.85), respectively.

CONCLUSION

An extreme heterogeneity of included studies was highlighted. Ultrasound evaluation of the diameter of the IVC and its respiratory variations does not seem to be a reliable method to predict fluid responsiveness.

Molecular Mechanisms Leading to Splanchnic Vasodilation in Liver Cirrhosis

In liver cirrhosis, portal hypertension is a consequence of enhanced intrahepatic vascular resistance and portal blood flow. Significant vasodilation in the arterial splanchnic district is crucial for an increase in portal flow. In this pathological condition, increased levels of circulating endogenous vasodilators, including nitric oxide, prostacyclin, carbon monoxide, epoxyeicosatrienoic acids, glucagon, endogenous cannabinoids, and adrenomedullin, and a decreased vascular response to vasoconstrictors are the main mechanisms underlying splanchnic vasodilation. In this review, the molecular pathways leading to splanchnic vasodilation will be discussed in detail.