Comparison of pulmonary vascular permeability index PVPI and global ejection fraction GEF derived from jugular and femoral indicator injection using the PiCCO-2 device: A prospective observational study

The influence of sex, age, and body height on the pulmonary vascular permeability index - a prospective observational study

The pulmonary vascular permeability index (PVPI) is a quotient of the extravascular lung water (EVLW) and the pulmonary blood volume (PBV). In acute respiratory distress syndrome (ARDS), the alveolar-capillary membrane integrity is disrupted. The result is a disproportionate increase of EVLW compared to the PBV and, hence, an increase in PVPI. Thus, PVPI has repetitively been discussed to extend the definition of ARDS. Besides sex, the influence of other anthropometric variables on PVPI has not been studied so far. However, since it is known that EVLW depends on body height and sex, we hypothesize that PVPI depends on anthropometric variables as well. This prospective single-center observational study included 1533 TPTD measurements of 251 non-critically ill patients (50.6% men) undergoing elective neuro-, thoracic, or abdominal surgery at the Munich Clinic Bogenhausen of the Technical University of Munich. Multivariate regressions were used to measure the influence of sex, age, and body height on PVPI. In all patients, PVPI was significantly higher in women (P < 0.001), with 34.4% having a PVPI > 2 compared to 15.9% of men. Mean PVPI significantly decreased with height (P < 0.001) and age (P < 0.001). Multivariate regressions allowed the calculation of mean reference surfaces. The 95th percentile surface for PVPI was > 3 for small and young women and well above 2 for all but tall and elderly men. In patients who underwent (lung reduction) thoracic surgery, the PVPI before and after surgery did not differ significantly (P = 0.531), and post-surgical PVPI did not correlate with the amount of lung resected (P = 0.536). Hence, we conclude that PVPI may be independent of the extent of lung volume reduction. However, PVPI is heavily dependent on sex, age, and body height. Anthropometric variables thus have a significant impact on the likelihood of misclassified abnormal PVPI. This warrants further studies since an increased PVPI, e.g. in the context of an ARDS, may be overlooked if anthropometric variables are not considered. We suggest reference surfaces based on the 95th-percentile corrected for sex, age, and height as a novel approach to normalize PVPI.

Contemporary Review of Hemodynamic Monitoring in the Critical Care Setting

Hemodynamic assessment remains the most valuable adjunct to physical examination and laboratory assessment in the diagnosis and management of shock. Through the years, multiple modalities to measure and trend hemodynamic indices have evolved with varying degrees of invasiveness. Pulmonary artery catheter (PAC) has long been considered the gold standard of hemodynamic assessment in critically ill patients and in recent years has been shown to improve clinical outcomes among patients in cardiogenic shock. The invasive nature of PAC is often cited as its major limitation and has encouraged development of less invasive technologies. In this review, the authors summarize the literature on the mechanism and validation of several minimally invasive and noninvasive modalities available in the contemporary intensive care unit. They also provide an update on the use of focused bedside echocardiography.

Accuracy, Precision, and Trending Ability of Perioperative Central Venous Oxygen Saturation Compared to Mixed Venous Oxygen Saturation in Unselected Cardiac Surgical Patients

OBJECTIVE

To determine whether central venous oxygen saturation (ScvO₂) measurements could be used interchangeably with mixed venous oxygen saturation (SvO₂) measurements in adult cardiac surgery patients.

DESIGN

A single-center prospective observational study.

SETTING

A university hospital.

PARTICIPANTS

Eighty-five adult patients undergoing cardiac surgery.

INTERVENTIONS

The study authors compared the oxygen saturations in 590 pairs of venous blood samples drawn from the pulmonary artery catheter (PAC) at three different time points during surgery and four different time points in the intensive care unit. They compared samples obtained from the distal pulmonary artery line (SvO₂) to those drawn from the proximal central venous line of the PAC (ScvO₂) with the Bland-Altman test and the four-quadrant method.

MEASUREMENTS AND MAIN RESULTS

The mean bias between SvO₂ and ScvO₂ was -1.9 (95% confidence interval [CI], -2.3 to -1.5) and the limits of agreement (LOA) were -11.5 to 7.6 (95% CI, -12.5 to -10.7 and 6.8-8.5, respectively). The percentage error (PE) was 13.2%. Based on the four-quadrant plot, only 50% of the measurement pairs were in agreement, indicating deficient trending ability.

CONCLUSION

ScvO₂ values showed acceptable accuracy as the mean bias was low. The precision was inadequate; although the PE was acceptable, the LOA were wide. Trending ability was inadequate. The authors cannot recommend the use of ScvO₂ values interchangeably with SvO₂ measurements in the management of adult cardiac surgery patients.

Increased extravascular lung water index (EVLWI) reflects rapid non-cardiogenic oedema and mortality in COVID-19 associated ARDS

Nearly 5% of patients suffering from COVID-19 develop acute respiratory distress syndrome (ARDS). Extravascular lung water index (EVLWI) is a marker of pulmonary oedema which is associated with mortality in ARDS. In this study, we evaluate whether EVLWI is higher in patients with COVID-19 associated ARDS as compared to COVID-19 negative, ventilated patients with ARDS and whether EVLWI has the potential to monitor disease progression. EVLWI and cardiac function were monitored by transpulmonary thermodilution in 25 patients with COVID-19 ARDS subsequent to intubation and compared to a control group of 49 non-COVID-19 ARDS patients. At intubation, EVLWI was noticeably elevated and significantly higher in COVID-19 patients than in the control group (17 (11–38) vs. 11 (6–26) mL/kg; p < 0.001). High pulmonary vascular permeability index values (2.9 (1.0–5.2) versus 1.9 (1.0–5.2); p = 0.003) suggested a non-cardiogenic pulmonary oedema. By contrast, the cardiac parameters SVI, GEF and GEDVI were comparable in both cohorts. High EVLWI values were associated with viral persistence, prolonged intensive care treatment and in-hospital mortality (23.2 ± 6.7% vs. 30.3 ± 6.0%, p = 0.025). Also, EVLWI showed a significant between-subjects (r = − 0.60; p = 0.001) and within-subjects correlation (r = − 0.27; p = 0.028) to Horowitz index. Compared to non COVID-19 ARDS, COVID-19 results in markedly elevated EVLWI-values in patients with ARDS. High EVLWI reflects a non-cardiogenic pulmonary oedema in COVID-19 ARDS and could serve as parameter to monitor ARDS progression on ICU.

Comparison of global end-diastolic volume index derived from jugular and femoral indicator injection: a prospective observational study in patients equipped with both a PiCCO-2 and an EV-1000-device

Transpulmonary thermodilution (TPTD)-derived global end-diastolic volume index (GEDVI) is a static marker of preload which better predicted volume responsiveness compared to filling pressures in several studies. GEDVI can be generated with at least two devices: PiCCO and EV-1000. Several studies showed that uncorrected indicator injection into a femoral central venous catheter (CVC) results in a significant overestimation of GEDVI by the PiCCO-device. Therefore, the most recent PiCCO-algorithm corrects for femoral indicator injection. However, there are no systematic data on the impact of femoral indicator injection for the EV-1000 device. Furthermore, the correction algorithm of the PiCCO is poorly validated. Therefore, we prospectively analyzed 14 datasets from 10 patients with TPTD-monitoring undergoing central venous catheter (CVC)- and arterial line exchange. PiCCO was replaced by EV-1000, femoral CVCs were replaced by jugular/subclavian CVCs and vice-versa. For PiCCO, jugular and femoral indicator injection derived GEDVI was comparable when the correct information about femoral catheter site was given (p = 0.251). By contrast, GEDVI derived from femoral indicator injection using the EV-1000 was obviously not corrected and was substantially higher than jugular GEDVI measured by the EV-1000 (846 ± 250 vs. 712 ± 227 ml/m²; p = 0.001). Furthermore, measurements of GEDVI were not comparable between PiCCO and EV-1000 even in case of jugular indicator injection (p = 0.003). This is most probably due to different indexations of the raw value GEDV. EV-1000 could not be recommended to measure GEDVI in case of a femoral CVC. Furthermore, different indexations used by EV-1000 and PiCCO should be considered even in case of a jugular CVC when comparing GEDVI derived from PiCCO and EV-1000.

Transpulmonary thermodilution techniques in the haemodynamically unstable patient

PURPOSE OF REVIEW

Transpulmonary thermodilution (TPTD) devices invasively measure not only cardiac output but also several other haemodynamic variables estimating cardiac preload, cardiac preload, systolic function, the lung oedema and systolic function, the lung oedema and the pulmonary permeability. In light of the recent literature, we describe how different indices are measured, emphasize their clinical interest and list potential limits and side-effects of the technique.

RECENT FINDINGS

Estimation of cardiac output measurement with TPTD is now well established, at least when compared with the pulmonary artery catheter. The advantage of calibrating the pulse contour analysis, as it is allowed by TPTD indices, is clearly established over uncalibrated devices. The greatest advantage of TPTD is to measure extravascular lung water and pulmonary permeability, which may be useful to diagnose acute respiratory distress syndrome and manage fluid therapy in various critical diseases. It also allows a rapid detection of left ventricular systolic failure. The information it provides must be considered complementary to that provided by echocardiography.

SUMMARY

TPTD provides several indices that may help in making decisions during the therapeutic management of haemodynamically unstable patients. It should be used for the most critically ill patients, whose management requires a reliable, precise and holistic view of the cardiopulmonary condition.

Comparison of cardiac function index derived from femoral and jugular indicator injection for transpulmonary thermodilution with the PiCCO-device: A prospective observational study

Introduction

Cardiac function index (CFI) is a trans-pulmonary thermodilution (TPTD)-derived estimate of systolic function. CFI is defined as the ratio of cardiac output divided by global end-diastolic volume GEDV (CFI = CO/GEDV). Several studies demonstrated that the use of femoral venous access results in a marked overestimation of GEDV, while CFI is underestimated. One study suggested a correction formula for femoral venous access that markedly reduced the bias for GEDVI. Therefore, the last PiCCO-algorithm requires information about the CVC-position which suggests a correction of GEDV for femoral access. However, a recent study demonstrated inconsistencies of the last PiCCO algorithm using incorrected GEDV to calculate CFI despite obvious correction of GEDV. Nevertheless, this study was based on mathematical analyses of data displayed in a total of 15 patients equipped with only a femoral, but not with a jugular CVC. Therefore, this study compared CFI derived from the femoral indicator injection TPTD to data derived from jugular indicator injection in 28 patients with both a jugular and a femoral CVC.

Methods

28 ICU-patients with PiCCO-monitoring were included. Each dataset consisted of three triplicate TPTDs using the jugular venous gold standard access and the femoral access with and without information about the femoral indicator injection to evaluate, if correction for femoral GEDV also pertains to CFI. (CFI_jug: jugular indicator injection; CFI_fem: femoral indicator injection; CFI_fem_cor: femoral indicator injection with correct information about CVC-position; CFI_fem_uncor: femoral indicator injection with uncorrect information about CVC-position; CFI_fem_uncor_form = CFI_fem_uncor * (GEDVI_fem_uncor/GEDVI_fem_cor)).

Results

CFI_fem_uncor was significantly lower than CFI_jug (4.28±1.70 vs. 5.21±1.91 min^-1; p<0.001). Similarly, CFI_fem_cor was significantly lower than CFI_jug (4.24±1.62 vs. 5.21±1.91 min^-1; p<0.001). This is explained by the finding that CFI_fem_uncor was not different to CFI_fem_cor (4.28±1.70 vs. 4.24±1.62 min^-1; p = 0.611). This suggests that correction for femoral CVC does not pertain to CFI. Calculative correction of CFI_fem_uncor by multiplying CFI_fem_uncor by the ratio GEDVI_fem_uncor/GEDVI_jug resulted in CFI_fem_uncor_form which was slightly, but significantly different from the gold standard CFI_jug (5.51±2.00 vs. 5.21±1.91 min^-1; p = 0.024). The agreement of measurements classified in the same category of CFI (decreased (<4.5), normal (4.5–6.5) and increased (>6.5 min^-1)) was high for CFI_jug and CFI_fem_uncor_form (identical categories in 26 of 28 comparisons; p = 0.49). By contrast, the agreement with CFI_jug was significantly lower for CFI_fem_cor (14 out of 28; p<0.001) and CFI_fem_uncor (15 out of 28; p<0.001).

Conclusions

While the last PiCCO algorithm obviously corrects GEDVI for femoral indicator injection, this correction is not applied to CFI. Therefore, femoral TPTD indicator injection results in substantially lower values for CFI compared to TPTD using a jugular CVC. Necessarily, uncorrected CFI-values derived from femoral TPTD are misleading and have to be corrected.