Respiratory Variation Of Stroke Volume Research Articles

The predictability of dynamic preload indices depends on the volume of fluid challenge

This study was designed to assess the association between volume of fluid challenge (FC) and predictability of respiratory variation of stroke volume (ΔrespSV) in the operating theater.Patients undergoing intermediate/high-risk surgery and monitored by esophageal Doppler monitoring (EDM) were prospectively included. All patients were under general anesthesia and mechanically ventilated. Exclusion criteria were frequent ectopic beats or preoperative arrhythmia, right ventricular failure, and spontaneous breathing. Hemodynamic parameters and esophageal Doppler indices (SV, cardiac output, ΔrespSV) were collected before, after infusion of 250 mL, and after infusion of 500 mL of crystalloid solution. Responders were defined by a >15% increase of stroke volume after FC at each step.After infusion of a 250 mL FC, 41 patients (32%) were classified as fluid responders (R250). After infusion of a 500 mL FC, 80 patients (63%) were classified as fluid responders (R500). The predictability of ΔrespSV was fair with an area under the curve (AUC) of 0.79 (95% CI 0.71–0.86, P < .001) to predict fluid responsiveness with a 250 mL FC. With an AUC of 0.94 (95% CI 0.88–0.97, P < .0001), ΔrespSV presented an excellent ability to predict fluid responsiveness with a 500-mL FC.Predictability of ΔrespSV changed with the volume of fluid infused to assess fluid responsiveness. The accuracy of ΔrespSV was higher with 500 mL than with 250 mL. Bedside studies evaluating the predictability of dynamic preload indices should define fluid responsiveness as a >15% increase of SV in response to a 500-mL FC.

Ultrasound assessment of volume responsiveness in critically ill surgical patients: Two measurements are better than one.

The intended physiologic response to a fluid bolus is an increase in stroke volume (SV). Several ultrasound (US) measures have been shown to be predictive. The best measure(s) in critically ill surgical patients remains unclear. This is a prospective observational study in critically ill surgical patients receiving a bolus of crystalloid, colloid or blood. A transthoracic echocardiogram was performed before (pre-transthoracic echocardiogram) and after. A positive volume response (+VR) was defined as a ≥15% increase in SV. Predictive measures were: left ventricular velocity time integral (VTI), respiratory SV variation (rSVV), passive leg raise SVV (plr SVV), positional internal jugular (IJ) vein change (0-90 degrees) and respiratory variation in the IJ sitting upright (90 degrees IJ). For each measure the area under the receiver operating curve (AUROC) was assessed and the best measure(s) determined. Between November 2013 and November 2015, 199 patients completed the study. After the pilot analyses, plr SVV was abandoned because it could not be reliably assessed. VTI, rv 90 degrees IJ, 0 degree to 90 degrees IJ, were all significantly associated with VR (p < 0.05), rSVV and rv inferior vena cava were not. For VTI AUROC was 0.71 (95% confidence interval [CI], 0.64-0.77). For rv 90 degrees, it was 0.65 (95% CI, 0.57-0.71), and 0.61 (95% CI, 0.54-0.69) for 0 degrees to 90 degrees IJ. When VTI and rv 90 degrees were considered together, the AUROC rose to 0.76 (95% CI, 0.69-0.82) for the population as a whole and 0.78 (95% CI, 0.69-0.85) in mechanically ventilated patients. The positive predictive value for combined assessment was 80% and the negative 70%. In a clinically relevant heterogeneous population, US is moderately predictive of VR. Inferior vena cava diameter change is not predictive. IJ change and VTI are the best measures, especially when used together. Future work should focus on combination metrics and the IJ. Diagnostic test, level II.

Early goal-directed therapy based on endotracheal bioimpedance cardiography: a prospective, randomized controlled study in coronary surgery.

The objective was to compare the impact of an early goal-directed hemodynamic therapy based on cardiac output monitoring (Endotracheal Cardiac Output Monitor, ECOM) with a standard of care on postoperative outcome following coronary surgery. This prospective, controlled, parallel-arm trial randomized 100 elective primary coronary artery bypass grafting patients to a study group (ECOM; n = 50) or a control group (control; n = 50). In the ECOM group, hemodynamic therapy was guided by respiratory stroke volume variation and cardiac index given by the ECOM system. A standard of care was used in the control. Goal-directed therapy was started immediately after induction of anesthesia and continued until arrival in the intensive care unit (ICU). The primary endpoint was the time when patients fulfilled discharge criteria from hospital (possible hospital discharge). Secondary endpoints were the hospital discharge, the time to reach extubation, the length of stay in ICU, the number of major adverse cardiac events, and in-hospital mortality. Patients in the ECOM group received more often fluid loading and dobutamine. The time to reach extubation was reduced in the ECOM group: 510 min [360-1,110] versus 570 min [320-1,520], P = 0.005. No significant differences were found between both groups for possible hospital discharge [Hazard Ratio = 0.96 (95 % CI 0.64-1.45)] and hospital discharge [Hazard Ratio = 1.20 (95 % CI 0.79-1.81)]. A mini-invasive early goal-directed hemodynamic therapy based on ECOM can reduce the time to reach extubation but fails to significantly reduce the length of stay in hospital and the rate of major cardiac morbidity.

The comparison between stroke volume variation and filling pressure as an estimate of right ventricular preload in patients undergoing renal transplantation.

The purpose of this prospective, observational study was to respiratory variation of stroke volume (stroke volume variation, SVV) against central venous pressure (CVP) and pulmonary artery diastolic pressure (PADP) as an estimate of right and left ventricular preload. With IRB approval and informed consent, 31 patients undergoing living related renal transplantation were analyzed. Under general anesthesia with positive pressure ventilation, stroke volume index and SVV were continuously monitored with FloTrac/Vigileo monitor. Right ventricular end-diastolic volume index (RVEDVI) as well as CVP and PADP were continuously monitored with volumetric pulmonary artery catheter. Data of every 30 min interval were used for analysis. The relationship between RVEDVI and CVP, PADP, SVV was analyzed with non-linear regression and the goodness-of-fit was assessed with coefficient of determination (R(2)) of each regression curve. The ability of CVP, PADP and SVV to correctly differentiate RVEDVI <100, <120 or >138 ml/m(2), which were used to guide fluid administration, was also assessed with ROC analysis. Three hundred forty-eight data sets were obtained and analyzed. The goodness of fit between RVEDVI and SVV (R(2)) = 0.48) was better than that between RVEDVI and CVP or PADP (R(2)) = 0.19 and 0.33, respectively). The area under the ROC curve of SVV was significantly high compared to CVP or PADP. This study confirmed the theoretical framework of right ventricular preload and ventricular filling pressure and respiratory variation of stroke volume. The result also suggests that SVV can correctly predict preload status compared to pressure-based indices.

End-expiratory occlusion manoeuvre does not accurately predict fluid responsiveness in the operating theatre

The objective of this study was to determine whether assessment of stroke volume (SV) and measurement of exhaled end-tidal carbon dioxide [Formula: see text] during an end-expiratory occlusion (EEO) test can predict fluid responsiveness in the operating theatre. Forty-two subjects monitored by oesophageal Doppler who required i.v. fluids during surgery were studied. Haemodynamic variables [heart rate, non-invasive arterial pressure, SV, cardiac output (CO), respiratory variation of SV (ΔrespSV), variation of SV during EEO, and E'(CO₂) were measured at baseline, during EEO (Δ(EEO)), and after fluid expansion. Responders were defined by an increase in SV over 15% after infusion of 500 ml of crystalloid solution. Of the 42 subjects, 28 (67%) responded to fluid infusion. A cut-off of >2.3% ΔSV(EEO) predicted fluid responsiveness with an area under the receiver-operating characteristic (AUC) curve of 0.78 [95% confidence interval (95% CI): 0.63-0.89, P=0.003]. The AUC of ΔrespSV was 0.89 (95% CI: 0.76-0.97, P<0.001). With an AUC of 0.68 (95% CI: 0.51-0.81, P=0.07), E'(CO₂)(EEO) was poorly predictive of fluid responsiveness. ΔSV(EEO) and ΔE'(CO₂) were unable to accurately predict fluid responsiveness during surgery.

The predictability of the respiratory variation of stroke volume varies according to the definition of fluid responsiveness

The predictability of the respiratory variation of stroke volume varies according to the definition of fluid responsiveness

Comparison of stroke volume (SV) and stroke volume respiratory variation (SVV) measured by the axillary artery pulse-contour method and by aortic Doppler echocardiography in patients undergoing aortic surgery

The goal of the study was to compare stroke volume (SV) and respiratory stroke volume variation (SVV) measured by pulse-contour analysis and aortic Doppler. These were measured by pulse-contour analysis and thermodilution (PiCCO) and by aortic pulsed wave Doppler with transoesophageal echocardiography in patients undergoing abdominal aortic surgery. Simultaneous measurements were done at different times of surgery. All data were recorded on PiCCOwin software and videotape and analysed off-line by a blinded investigator. A total of 114 measurements were achieved in 20 patients. There was a good correlation and small bias between the PiCCO and the echo-Doppler values of the mean SV [r=0.885; bias=0.2 (8) ml], and between the minimum [r=0.842; bias=1 (9) ml] and maximum SV [r=0.840; bias=2 (10) ml] values. There is a fair correlation between pulse-contour analysis and aortic Doppler for beat-by-beat measurement of SV but not for calculation of SV respiratory ventilation.

Passive leg raising predicts fluid responsiveness in the critically ill*

Passive leg raising (PLR) represents a "self-volume challenge" that could predict fluid response and might be useful when the respiratory variation of stroke volume cannot be used for that purpose. We hypothesized that the hemodynamic response to PLR predicts fluid responsiveness in mechanically ventilated patients. Prospective study. Medical intensive care unit of a university hospital. We investigated 71 mechanically ventilated patients considered for volume expansion. Thirty-one patients had spontaneous breathing activity and/or arrhythmias. We assessed hemodynamic status at baseline, after PLR, and after volume expansion (500 mL NaCl 0.9% infusion over 10 mins). We recorded aortic blood flow using esophageal Doppler and arterial pulse pressure. We calculated the respiratory variation of pulse pressure in patients without arrhythmias. In 37 patients (responders), aortic blood flow increased by > or =15% after fluid infusion. A PLR increase of aortic blood flow > or =10% predicted fluid responsiveness with a sensitivity of 97% and a specificity of 94%. A PLR increase of pulse pressure > or =12% predicted volume responsiveness with significantly lower sensitivity (60%) and specificity (85%). In 30 patients without arrhythmias or spontaneous breathing, a respiratory variation in pulse pressure > or =12% was of similar predictive value as was PLR increases in aortic blood flow (sensitivity of 88% and specificity of 93%). In patients with spontaneous breathing activity, the specificity of respiratory variations in pulse pressure was poor (46%). The changes in aortic blood flow induced by PLR predict preload responsiveness in ventilated patients, whereas with arrhythmias and spontaneous breathing activity, respiratory variations of arterial pulse pressure poorly predict preload responsiveness.