Comparison of pulmonary artery and central venous pressure waveform measurements via digital and graphic measurement methods

Twelve-month follow-up results from the SIRONA 2 clinical trial

AIMS

In the SIRONA 2 trial, the safety and efficacy of pulmonary artery (PA) pressure (PAP)-guided heart failure (HF) management using a novel PAP sensor were assessed at 30 and 90 days, respectively, and both endpoints were met. The current study examines the prespecified secondary endpoints of safety and accuracy of the PA sensor along with HF hospitalizations and mortality, HF symptoms, functional capacity, quality of life, and patient compliance through 12 months.

METHODS AND RESULTS

SIRONA 2 is a prospective, multi-centre, open-label, single-arm trial evaluating the Cordella™ PA Sensor System in 70 patients with New York Heart Association (NYHA) functional class III HF with a prior HF hospitalization and/or increase of N-terminal pro-brain natriuretic peptide within 12 months of enrolment. Sensor accuracy was assessed and compared with measurements obtained by standard right heart catheterization (RHC). Safety was defined as freedom from prespecified adverse events associated with use of the Cordella PA Sensor System and was assessed in all patients who entered the cath lab for PA sensor implant. HF hospitalizations and mortality, HF symptoms, functional capacity, quality of life, and patient compliance were also assessed. At 12 months, there was good agreement between the Cordella PA Sensor System and RHC, with the average difference for mean PAP being 2.9 ± 7.3 mmHg. The device safety profile was excellent with 98.4% freedom from device/system-related complications. There were no pressure sensor failures. HF hospitalizations and mortality were low with a rate of 0.33 event per patient year. Symptoms as assessed by NYHA (P < 0.0001) and functional capacity as measured by 6 min walk test (P = 0.02) were significantly improved. Patients' adherence to daily transmissions of PAP and vital signs measurements was 95%.

CONCLUSIONS

Long-term follow-up of the SIRONA 2 trial supports the safety and accuracy of the Cordella PA Sensor System in enabling comprehensive HF management in NYHA class III HF patients.

Narrative History of the Swan-Ganz Catheter: Development, Education, Controversies, and Clinician Acumen

The year 2020 marks the 50th anniversary of the landmark publication on the bedside clinical use of a flow-directed catheter. The catheter, now known as the Swan-Ganz catheter, truly revolutionized practice and care of the critically ill. Use of the catheter proliferated nearly without rigorous validation or evidence base until a moratorium was called in regard to its use. This article describes the history of the development of the Swan-Ganz catheter, its uses, and its near downfall. The authors, both involved in educating clinicians in the use of the pulmonary artery catheter, hope that telling this story shares tribal knowledge and lessons learned with newer generations of nurses who did not experience the explosion of development and knowledge in the area of hemodynamic monitoring. Partly because of advances in technology, and the catheter's application for heart failure in particular, use of the pulmonary catheter is being resurrected.

Comparison of different techniques of central venous pressure measurement in mechanically ventilated critically ill patients

BACKGROUND

Several techniques exist for measuring central venous pressure (CVP) but little information is available about the accuracy of each method. The aim of this study was to compare different methods of CVP measurements in mechanically ventilated patients.

METHODS

CVP was measured in mechanically ventilated patients without spontaneous breathing using four different techniques: 1) end expiratory CVP measurement at the base of the" c" wave (CVP_MEASURED), chosen as the reference method; 2) CVP measurement from the monitor averaging CVP over the cardiac and respiratory cycles (CVP_MONITOR); 3) CVP measurement after a transient withdrawing of mechanical ventilation (CVP_NADIR); 4) CVP measurement corrected for the transmitted respiratory pressure induced by intrinsic PEEP (calculated CVP: CVP_CALCULATED). Bias, precision, limits of agreement, and proportions of outliers (difference > 2 mm Hg) were determined.

RESULTS

Among 61 included patients, 103 CVP assessments were performed. CVP_MONITOR bias [-0.87  (1.06) mm Hg] was significantly different from those of CVP_CALCULATED [1.42  (1.07), P < 0.001 and CVP_NADIR (1.04  (1.29), P < 0.001]. The limits of agreement of CVP_MONITOR [-2.96 to 1.21 mm Hg] were not significantly different to those of CVP_NADIR (-1.49 to 3.57 mm Hg, P = 0.39) and CVP_CALCULATED (-0.68 to 3.53 mm Hg, P = 0.31). The proportion of outliers was not significantly different between CVP_MONITOR (n = 5, 5%) and CVP_NADIR (n = 9, 9%, P = 0.27) but was greater with CVP_CALCULATED (n = 16, 15%, P = 0.01).

CONCLUSIONS

In mechanically ventilated patients, CVP_MONITOR is a reliable method for assessing CVP_MEASURED Taking into account transmitted respiratory pressures, CVP_CALCULATED had a higher proportion of outliers and precision than CVP_NADIR.

Reliance on end-expiratory wedge pressure leads to misclassification of pulmonary hypertension

Current guidelines recommend measurement of pulmonary artery wedge pressure (PAWP) at end-expiration. However, this recommendation is not universally followed and may not be physiologically appropriate. We investigated the performance of end-expiratory PAWP in the evaluation of precapillary pulmonary hypertension patients. 329 spontaneously breathing patients undergoing right heart catheterisation were retrospectively classified as having a precapillary, post-capillary or mixed phenotype based on standardised clinical criteria. Tracings were reviewed to compare end-expiratory PAWP with PAWP averaged throughout the respiratory cycle; these values were correlated with the clinical classifications. Predictors of large respirophasic variation in PAWP were determined. Elevated end-expiratory PAWP (>15 mmHg) occurred in 29% of subjects with precapillary phenotype. There were no differences in demographics or clinical history between those with elevated and normal end-expiratory PAWP. Those with elevated end-expiratory PAWP had greater right atrial pressure and respirophasic PAWP variation. Among all subjects, the magnitude of respirophasic variation in PAWP was positively correlated with body mass index and respirophasic variation in left ventricular end-diastolic pressure. A significant proportion of precapillary pulmonary hypertension patients have end-expiratory PAWP >15 mmHg. Spontaneous positive end-expiratory intrathoracic pressure may contribute; in those cases, PAWP averaged throughout respiration may be a more accurate measurement.

Evaluation of the monitor cursor-line method for measuring pulmonary artery and central venous pressures

OBJECTIVE

To determine if the monitor cursor-line feature on bedside monitors is accurate for measuring central venous and pulmonary artery pressures in cardiac surgery patients.

METHODS

Central venous and pulmonary artery pressures were measured via 3 methods (end-expiratory graphic recording, monitor cursor-line display, and monitor digital display) in a convenience sample of postoperative cardiac surgery patients. Pressures were measured twice during both mechanical ventilation and spontaneous breathing. Analysis of variance was used to determine differences between measurement methods and the percentage of monitor pressures that differed by 4 mm Hg or more from the measurement obtained from the graphic recording. Significance level was set at P less than .05.

RESULTS

Twenty-five patients were studied during mechanical ventilation (50 measurements) and 21 patients during spontaneous breathing (42 measurements). Measurements obtained via the 3 methods did not differ significantly for either type of pressure (P > .05). Graphically recorded pressures and measurements obtained via the monitor cursor-line or digital display methods differed by 4 mm Hg or more in 4% and 6% of measurements, respectively, during mechanical ventilation and 4% and 11%, respectively, during spontaneous breathing.

CONCLUSION

The monitor cursor-line method for measuring central venous and pulmonary artery pressures may be a reasonable alternative to the end-expiratory graphic recording method in hemodynamically stable, postoperative cardiac surgery patients. Use of the digital display on the bedside monitor may result in larger discrepancies from the graphically recorded pressures than when the cursor-line method is used, particularly in spontaneously breathing patients.

Pulmonary artery catheters: state of the controversy

Since 1970, pulmonary artery catheters (PACs) have been used in clinical practice to monitor the hemodynamic status of critically ill and injured patients. This technology was introduced and commercialized without considerable testing to determine safety and efficacy. After years of common clinical use, investigators identified potential increases in mortality associated with PAC use. For the past decade, investigators have studied various patient populations to elucidate the safety and efficacy of the PAC. This article reviews the historical context of PAC use, findings from recent clinical trials intended to determine safety and efficacy, issues with reliability and validity of PAC use, and complications associated with PAC use. Data from recent clinical trials do not support routine use of PACs, and the authors suggest that PAC-guided therapy should be the focus of study in future trials.

Central venous pulse pressure analysis using an R-synchronized pressure measurement system

OBJECTIVE

The information derived from central venous catheters is underused. We developed an EKG-R synchronization and averaging system to obtained distinct CVP waveforms and analyzed components of these.

METHODS

Twenty-five paralyzed surgical patients undergoing CVP monitoring under mechanical ventilation were studied. CVP and EKG signals were analyzed employing our system, the mean CVP and CVP at end-diastole during expiration were compared, and CVP waveform components were measured using this system.

RESULTS

CVP waveforms were clearly visualized in all patients. They showed the a peak to be 1.8+/- 0.7 mmHg, which was the highest of three peaks, and the x trough to be lower than the y trough (-1.6+/- 0.7 mmHg and -0.9+/- 0.5 mmHg, respectively), with a mean pulse pressure of 3.4 mmHg. The difference between the mean CVP and CVP at end-diastole during expiration was 0.58+/- 0.81 mmHg.

CONCLUSIONS

The mean CVP can be used as an index of right ventricular preload in patients under mechanical ventilation with regular sinus rhythm. Our newly developed system is useful for clinical monitoring and for education in circulatory physiology.

Hemodynamic Assessment

Hemodynamic monitoring has become an integral component of the assessment of the critically ill. Any technology used for monitoring is a diagnostic tool and only as good as the provider interpreting the data. The article focuses on providing the practitioner the physiologic basis of the hemodynamic profile to cross the chasm of turning data into clinically useful information. Decision-making models are described to facilitate data synthesis and clinical intervention.