Should we use diastolic function parameters to determine preload responsiveness in cardiac surgery? A pilot study

Background Left ventricular (LV) diastolic function (DF) may play an important role in predicting fluid responsiveness. However, few studies assessed the role of diastolic function in predicting fluid responsiveness. The aim of this pilot study was to assess whether parameters of right and left diastolic function assessed with transesophageal echocardiography, including the mitral E/e′ ratio, is associated with fluid responsiveness among patients undergoing elective bypass graft surgery. We also sought to compare other methods of fluid responsiveness assessment, including echocardiographic and hemodynamic parameters, pulse pressure variation, and stroke volume variation (SVV) (arterial pulse contour analysis, Flotrac/Vigileo system). Results We prospectively studied seventy patients undergoing coronary artery bypass grafting (CABG) monitored with a radial arterial catheter, transesophageal echocardiography (TEE), and a pulmonary artery catheter (for cardiac output measurements), before and after the administration of 500 mL of crystalloid over 10 min after the anesthetic induction. Thirteen patients were excluded (total of 57 patients). Fluid responsiveness was defined as an increase in cardiac index of ≥ 15%. There were 21 responders (36.8%) and 36 non-responders (63.2%). No difference in baseline pulsed wave Doppler echocardiographic measurements of any components of the mitral, tricuspid, and pulmonary and hepatic venous flows were found between responders and non-responders. There was no difference in MV tissue Doppler measurements between responders and non-responders, including E/e′ ratio (8.7 ± 4.1 vs. 8.5 ± 2.8 in responders vs. non-responders, P = 0.85). SVV was the only independent variable to predict an increase in cardiac index by multivariate analysis (P = 0.0208, OR = 1.196, 95% CI (1.028-1.393)). Conclusions In this pilot study, we found that no parameters of right and left ventricular diastolic function were associated with fluid responsiveness in patients undergoing CABG. SVV was the most useful parameter to predict fluid responsiveness. Trial registration ClinicalTrials.gov, NCT 02714244. Registered 21 March 2016—retrospectively registered.

Bioreactance reliably detects preload responsiveness by the end-expiratory occlusion test when averaging and refresh times are shortened

Background The end-expiratory occlusion (EEXPO) test detects preload responsiveness, but it is 15 s long and induces small changes in cardiac index (CI). It is doubtful whether the Starling bioreactance device, which averages CI over 24 s and refreshes the displayed value every 4 s (Starling-24.4), can detect the EEXPO-induced changes in CI (ΔCI). Our primary goal was to test whether this Starling device version detects preload responsiveness through EEXPO. We also tested whether shortening the averaging and refresh times to 8 s and one second, respectively, (Starling-8.1) improves the accuracy of the device in detecting preload responsiveness using EEXPO. Methods In 42 mechanically ventilated patients, during a 15-s EEXPO, we measured ∆CI through calibrated pulse contour analysis (CIpulse, PiCCO2 device) and using the Starling device. For the latter, we considered both CIStarling-24.4 from the commercial version and CIStarling-8.1 derived from the raw data. For relative ∆CIStarling-24.4 and ∆CIStarling-8.1 during EEXPO, we calculated the area under the receiver operating characteristic curve (AUROC) to detect preload responsiveness, defined as an increase in CIpulse ≥ 10% during passive leg raising (PLR). For both methods, the correlation coefficient vs. ∆CIpulse was calculated. Results Twenty-six patients were preload responders and sixteen non preload-responders. The AUROC for ∆CIStarling-24.4 was significantly lower compared to ∆CIStarling-8.1 (0.680 ± 0.086 vs. 0.899 ± 0.049, respectively; p = 0.027). A significant correlation was observed between ∆CIStarling-8.1 and ∆CIpulse (r = 0.42; p = 0.009), but not between ∆CIStarling-24.4 and ∆CIpulse. During PLR, both ∆CIStarling-24.4 and ∆CIStarling-8.1 reliably detected preload responsiveness. Conclusions Shortening the averaging and refresh times of the bioreactance signal to 8 s and one second, respectively, increases the reliability of the Starling device in detection of EEXPO-induced ∆CI. Trial registration: No. IDRCB:2018-A02825-50. Registered 13 December 2018.

Norepinephrine potentiates the efficacy of volume expansion on mean systemic pressure in septic shock

Background Through venous contraction, norepinephrine (NE) increases stressed blood volume and mean systemic pressure (Pms) and exerts a “fluid-like” effect. When both fluid and NE are administered, Pms may not only result from the sum of the effects of both drugs. Indeed, norepinephrine may enhance the effects of volume expansion: because fluid dilutes into a more constricted, smaller, venous network, fluid may increase Pms to a larger extent at a higher than at a lower dose of NE. We tested this hypothesis, by mimicking the effects of fluid by passive leg raising (PLR). Methods In 30 septic shock patients, norepinephrine was decreased to reach a predefined target of mean arterial pressure (65–70 mmHg by default, 80–85 mmHg in previously hypertensive patients). We measured the PLR-induced increase in Pms (heart–lung interactions method) under high and low doses of norepinephrine. Preload responsiveness was defined by a PLR-induced increase in cardiac index ≥ 10%. Results Norepinephrine was decreased from 0.32 [0.18–0.62] to 0.26 [0.13–0.50] µg/kg/min (p < 0.0001). This significantly decreased the mean arterial pressure by 10 [7–20]% and Pms by 9 [4–19]%. The increase in Pms (∆Pms) induced by PLR was 13 [9–19]% at the higher dose of norepinephrine and 11 [6–16]% at the lower dose (p < 0.0001). Pms reached during PLR at the high dose of NE was higher than expected by the sum of Pms at baseline at low dose, ∆Pms induced by changing the norepinephrine dose and ∆Pms induced by PLR at low dose of NE (35.6 [11.2] mmHg vs. 33.6 [10.9] mmHg, respectively, p < 0.01). The number of preload responders was 8 (27%) at the high dose of NE and 15 (50%) at the low dose. Conclusions Norepinephrine enhances the Pms increase induced by PLR. These results suggest that a bolus of fluid of the same volume has a greater haemodynamic effect at a high dose than at a low dose of norepinephrine during septic shock.

Pleth variability index may predict preload responsiveness in patients treated with nasal high flow: a physiological study

The purpose of this study was to determine whether the plethysmographic variability index (PVi) can predict preload responsiveness in nasal high flow (NHF) patients (≥30 L/min) with any sign of hypoperfusion. Preload responsiveness was defined as a ≥10% increase in stroke volume (SV), measured by transthoracic echocardiography, after passive leg raising. SV and PVi were reassessed in preload responders after receiving a 250-mL fluid challenge. Twenty patients were included, and 12 patients (60%) were preload responders. Responders showed higher baseline mean PVi (24% vs. 13%; p=0.001) and higher mean PVi variation (∆PVi) after passive leg raising (6.8% vs. -1.7%; p<0.001). No differences between mean ∆PVi after passive leg raising and mean ∆PVi after fluid challenge were observed (6.8 % vs. 7.4%; p=0.24), and both values were strongly correlated (r=0.84; p<0.001). Baseline PVi and ∆PVi after passive leg raising showed excellent diagnostic accuracy identifying preload responders (AUROC 0.92 and 1.00, respectively). Baseline PVi ≥16% had a sensitivity of 91.7% and a specificity of 87.5% for detecting preload responders. Similarly, ∆PVi after passive leg raising ≥2%, had a 100% of both sensitivity and specificity. Thus, PVi might predict preload responsiveness in patients treated with NHF, suggesting that it may guide fluid administration in these patients.

Do changes in pulse pressure variation and inferior vena cava distensibility during passive leg raising and tidal volume challenge detect preload responsiveness in case of low tidal volume ventilation?

Background In patients ventilated with tidal volume (Vt) < 8 mL/kg, pulse pressure variation (PPV) and, likely, the variation of distensibility of the inferior vena cava diameter (IVCDV) are unable to detect preload responsiveness. In this condition, passive leg raising (PLR) could be used, but it requires a measurement of cardiac output. The tidal volume (Vt) challenge (PPV changes induced by a 1-min increase in Vt from 6 to 8 mL/kg) is another alternative, but it requires an arterial line. We tested whether, in case of Vt = 6 mL/kg, the effects of PLR could be assessed through changes in PPV (ΔPPVPLR) or in IVCDV (ΔIVCDVPLR) rather than changes in cardiac output, and whether the effects of the Vt challenge could be assessed by changes in IVCDV (ΔIVCDVVt) rather than changes in PPV (ΔPPVVt). Methods In 30 critically ill patients without spontaneous breathing and cardiac arrhythmias, ventilated with Vt = 6 mL/kg, we measured cardiac index (CI) (PiCCO2), IVCDV and PPV before/during a PLR test and before/during a Vt challenge. A PLR-induced increase in CI ≥ 10% defined preload responsiveness. Results At baseline, IVCDV was not different between preload responders (n = 15) and non-responders. Compared to non-responders, PPV and IVCDV decreased more during PLR (by − 38 ± 16% and − 26 ± 28%, respectively) and increased more during the Vt challenge (by 64 ± 42% and 91 ± 72%, respectively) in responders. ∆PPVPLR, expressed either as absolute or as percent relative changes, detected preload responsiveness (area under the receiver operating curve, AUROC: 0.98 ± 0.02 for both). ∆IVCDVPLR detected preload responsiveness only when expressed in absolute changes (AUROC: 0.76 ± 0.10), not in relative changes. ∆PPVVt, expressed as absolute or percent relative changes, detected preload responsiveness (AUROC: 0.98 ± 0.02 and 0.94 ± 0.04, respectively). This was also the case for ∆IVCDVVt, but the diagnostic threshold (1 point or 4%) was below the least significant change of IVCDV (9[3–18]%). Conclusions During mechanical ventilation with Vt = 6 mL/kg, the effects of PLR can be assessed by changes in PPV. If IVCDV is used, it should be expressed in percent and not absolute changes. The effects of the Vt challenge can be assessed on PPV, but not on IVCDV, since the diagnostic threshold is too small compared to the reproducibility of this variable. Trial registration: Agence Nationale de Sécurité du Médicament et des Produits de santé: ID-RCB: 2016-A00893-48.

Do Changes in Pulse Pressure Variation and Inferior Vena Cava Distensibility During Passive Leg Raising and Tidal Volume Challenge Detect Preload Responsiveness in Case of Low Tidal Volume Ventilation?

BackgroundIn patients ventilated with tidal volume (Vt) <8 mL/kg, pulse pressure variation (PPV) and, likely, the distensibility of the inferior vena cava diameter (IVCV) are unable to detect preload responsiveness. In this condition, passive leg raising (PLR) could be used but it requires a measurement of cardiac output. The tidal volume (Vt) challenge (PPV changes induced by a 1-min increase in Vt from 6 to 8 mL/kg) is another alternative, but it requires an arterial line. We tested whether, in case of Vt=6mL/kg, the effects of PLR could be assessed through changes in PPV or in IVCV rather than changes in cardiac output, and whether the effects of the Vt challenge could be assessed by changes in IVCV rather than changes in PPV.MethodsIn 30 critically ill patients without spontaneous breathing and cardiac arrhythmias, ventilated with Vt=6 mL/kg, we measured cardiac index (CI) (PiCCO2), IVCV and PPV before/during a PLR test and before/during a Vt challenge. A PLR-induced increase in CI ≥10% defined preload responsiveness.ResultsAt baseline, IVCV was not different between preload responders (n=15) and non-responders. Compared to non-responders, PPV and IVCV decreased more during PLR (by -38±16% and -26±28%, respectively) and increased more during the Vt challenge (by 64±42% and 91±72%, respectively) in responders. ∆PPVPLR, expressed either as absolute or percent relative changes, detected preload responsiveness (area under the receiver operating curve, AUROC: 0.98±0.02 for both). ∆IVCVPLR detected preload responsiveness only when expressed in absolute changes (AUROC: 0.76±0.10), not in relative changes. ∆PPVVt, expressed as absolute or percent relative changes, detected preload responsiveness (AUROC: 0.98±0.02 and 0.94±0.04, respectively). This was also the case for ∆IVCVVt but, the diagnostic threshold (1 point or 4%) was below the least significant change of IVCV (9[3-18]%).ConclusionsDuring mechanical ventilation with Vt=6 mL/kg, the effects of PLR can be assessed by changes in PPV. If IVCV is used, it should be expressed in percent and not in absolute changes. The effects of the Vt challenge can be assessed on PPV, but not on IVCV, since the diagnostic threshold is too small with regards to the reproducibility of this variable.Trial registrationIDRCB: 2016-A00893-48