The Swan-Ganz Catheter: A decade of hemodynamic monitoring

Diagnostic and prognostic utility of brain natriuretic Peptide in subjects admitted to the ICU with hypoxic respiratory failure due to noncardiogenic and cardiogenic pulmonary edema

BACKGROUND

Brain natriuretic peptide (BNP) is useful in diagnosing congestive heart failure (CHF) in patients presenting in the emergency department with acute dyspnea. We prospectively tested the utility of BNP for discriminating ARDS vs cardiogenic pulmonary edema (CPE).

METHODS

We enrolled ICU patients with acute hypoxemic respiratory failure and bilateral pulmonary infiltrates who were undergoing right-heart catheterization (RHC) to aid in diagnosis. Patients with acute coronary syndrome, end-stage renal disease, recent coronary artery bypass graft surgery, or preexisting left ventricular ejection fraction </= 30% were excluded. BNP was measured at RHC. Two intensivists independently reviewed the records to determine the final diagnosis.

RESULTS

Eighty patients were enrolled. Median BNP was 325 pg/mL (interquartile range [IQR], 82 to 767 pg/mL) in acute lung injury/ARDS patients, vs 1,260 pg/mL (IQR, 541 to 2,020 pg/mL) in CPE patients (p = 0.0001). The correlation between BNP and pulmonary capillary wedge pressure was modest (r = 0.27, p = 0.02). BNP offered good discriminatory performance for the final diagnosis (C-statistic, 0.80). At a cut point </= 200 pg/mL, BNP provided specificity of 91% for ARDS. At a cut point >/= 1,200 pg/mL, BNP had a specificity of 92% for CPE. Higher levels of BNP were associated with a decreased odds for ARDS (odds ratio, 0.4 per log increase; p = 0.007) after adjustment for age, history of CHF, and right atrial pressure. BNP was associated with in-hospital mortality (p = 0.03) irrespective of the final diagnosis and independent of APACHE (acute physiology and chronic health evaluation) II score.

CONCLUSION

In ICU patients with hypoxemic respiratory failure, BNP appears useful in excluding CPE and identifying patients with a high probability of ARDS, and was associated with mortality in patients with both ARDS and CPE. Larger studies are necessary to validate these findings.

Hemodynamic changes after self-expandable metallic stent therapy for vena cava syndrome

OBJECTIVE

We examined changes in hemodynamics after self-expandable metallic stent placement in the vena cava.

CONCLUSION

The rapid increase in venous return immediately after expandable metallic stent placement influenced the hemodynamics of the circulatory system.

The pulmonary artery catheter: uses and controversies

The pulmonary artery catheter is an invasive hemodynamic monitor that can provide diagnostic information in situations where history and physical examination are inconclusive. Assisting the physician in therapeutic decisions has added to its clinical value. Understanding the information it provides and making thoughtful therapeutic decisions lie at the core of its use. Despite its use, the PA catheter has been the center of great controversy. Clearly the paucity of prospective randomized trials proving its efficacy is alarming. The inability of physicians to interpret the provided data properly is also unacceptable. Although instituting a moratorium on its use may be extreme, limiting its use to approved indications seems more appropriate. In the future, ready availability of other less invasive methods such as echocardiography may allow clinicians to become less reliant on the PA catheter. Until then, clinicians would be served best by comprehending the intricacies and the limitations of this sophisticated instrument.

Prediction of postoperative cardiac surgical morbidity and organ failure within 4 hours of intensive care unit admission using esophageal Doppler ultrasonography

OBJECTIVE

To compare esophageal Doppler ultrasonography with standard hemodynamic variables used in postoperative care for the prediction of postoperative complications after cardiac surgery.

DESIGN

Prospective, observational pilot study.

SETTING

University hospital, multidisciplinary intensive care unit

PATIENTS

Postoperative cardiac surgical patients.

INTERVENTIONS

Standard postoperative management as guided by routinely measured hemodynamic variables.

MEASUREMENTS

An esophageal Doppler ultrasound probe was inserted for measurement of stroke volume (SV), cardiac output (CO), and other flow-related variables. Both these and routine hemodynamic variables (mean arterial pressure, central venous pressure, heart rate, arterial base deficit, urine output, core-toe temperature difference) were recorded at half-hourly intervals for the first 4 postoperative hrs. The incidence of systemic inflammatory response syndrome at 24 hrs, Acute Physiology and Chronic Health Evaluation II, and multiple organ failure scores, postoperative complications, and length of ICU and hospital stays were recorded.

MAIN RESULTS

Twenty consecutively admitted patients were studied: eight after emergency bypass grafting and 12 after elective bypass grafts and/or valve replacement. Of the nine patients who developed postoperative complications, two died. At admission, significant differences were seen between patients with a complicated and those with an uncomplicated surgical procedure for SV, heart rate, and standard base excess, but not for cardiac output. By using receiver operator characteristic curves, SV was the best marker for predicting postoperative complications during the initial postoperative period.

CONCLUSIONS

A low SV and a high heart rate, both at ICU admission and during the subsequent 4 hrs, were the best prognostic factors for development of complications after cardiac surgery. Cardiac output values were not useful. This pilot study suggests that the minimally invasive technique of esophageal Doppler ultrasonography may be a useful tool to assist early prognostication.

Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients

PURPOSE

Recent observations have highlighted errors in the thermodilution technique of measuring cardiac output. Thus, cardiac output measurements using transesophageal echocardiography and the Fick method were compared with simultaneous thermodilution measurements.

METHODS

In 13 mechanically ventilated critically ill patients, cardiac output was determined simultaneously using (1) transesophageal echocardiography (COTEE, (2) the Fick method (COFICK, and (3) thermodilution (COTD immediately before and after a rapid infusion of 500 mL of saline. Left ventricular end-diastolic and end-systolic areas were measured using the transesophageal echocardiographic transgastric short axis view, and COTEE was calculated from the corresponding volumes. Absolute cardiac output values and the changes from before to after saline infusion (delta CO) were compared using analysis of variance, linear regression, and the Bland and Altman method.

RESULTS

There were no significant differences between COTEE (8.0 +/- 3.4), COFICK (8.4 +/- 3.3), and COTD (8.3 +/- 3.0) or between delta COTEE, delta COFICK, and delta COTD using analysis of variance. However, correlations between COTEE and COTD (r2 = 0.46; P < .00001), COFICK and COTD (r2 = 0.46; P < .0001), and COTEE and COFICK (r2 = 0.42; P < .0001) were only moderately good. Using the method of Bland and Altman, the mean difference (+/-2 standard deviations) between COTEE and COTD was 0.3 +/- 4.3 L/min, between COFICK and COTD was -1.0 +/- 3.8 L/min, and between COTEE and COFICK was 0.6 +/- 5.6 L/min, whereas the difference between delta COTEE and delta COTD was 0% +/- 26%, between delta COFICK and delta COTD was 9% +/- 46%, and between delta COTEE and delta COFICK was 8% +/- 39%.

CONCLUSIONS

There are substantial differences in cardiac output as measured by these three methods, best demonstrated using the method of Bland and Altman. The variability of cardiac output and its derivatives (eg, oxygen delivery) should be borne in mind when making clinical decisions on individual patients.

Triage of critically ill patients: an overview of interventions

The recognition of tissue hypoxia or cumulative oxygen debt is of fundamental importance for triage and resuscitation of critically ill patients during the ¿golden hour¿ in the emergency department (ED). The measurement of central venous blood oxygen saturation, plasma lactate concentration, cardiac output, systemic oxygen transport and use, and non-vital organ oxygenation and function can enhance the detection of systemic and regional hypoperfusion and tissue hypoxia. Systemic and organ-specific oxygenation indices may guide the choice of therapy to optimize resuscitation of the macrocirculation and microcirculation in critically ill ED patients.

An argument for colloid resuscitation for shock

A focused review of the physiologic mechanisms of colloid and crystalloid fluid resuscitations for acute critical illness is presented. This review suggests that postresuscitation plasma volume, cardiac output, left ventricular mechanical performance, and global and microcirculatory O2 supplies are more favorable with colloid therapy. Conversely, crystalloid may adversely affect microcirculatory blood flow and resultant O2 supply and use by ischemic tissues in shock. Poor relief of global and regional hypoxia may persist in critically ill patients after resuscitation with crystalloid.

Central venous catheter related sepsis: a clinical review

Central venous catheterization is one of the most common invasive vascular procedures performed in hospitals today. Though catheter related sepsis occurs only in a small percentage of catheterized patients, this complication has a tremendous impact due to the ubiquitous use of central venous catheters and consequent morbidity and even mortality. Recent studies have considerably advanced our knowledge regarding the pathogenesis, diagnosis, and prevention of catheter sepsis. In this paper, current concepts regarding catheter-related sepsis are reviewed, regarding the incidence, pathophysiology, diagnosis, prevention, and therapy of this complication. Particular emphasis is placed upon recent research and clinical advances in this field, which have clarified important question and suggested promising approaches to the prevention and treatment of catheter bacteremia. The excessive morbidity and mortality due to catheter-related sepsis can be markedly decreased, by attention to simple infection control methods, and by future implementation of new experimental techniques.