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Changes in stroke volume (deltaSV) induced by a lung recruitment manoeuvre (LRM) have been shown to accurately predict fluid responsiveness during protective mechanical ventilation. Cardiac output monitors are used in a limited number of surgical patients. In contrast, all patients are monitored with a pulse oximeter, that may enable the continuous monitoring of a peripheral perfusion index (PI). We postulated that changes in PI (deltaPI) may reflect deltaSV during brief modifications of cardiac preload. We studied 47 patients undergoing neurosurgery and ventilated with a tidal volume of 6-8 ml/kg. All patients were monitored with a pulse contour system enabling the continuous monitoring of SV and with a pulse oximeter enabling the continuous monitoring of PI. LRMs were performed by increasing airway pressure up to 30 cmH20 for 30 s. Fluid loads (250 ml of saline 0.9% in 10 min) were performed only in patients who experienced a deltaSV > 30% during LRMs (potential fluid responders). LRMs induced a 26% decrease in SV (p < 0.05) and a 27% decrease in PI (p < 0.05). We observed a fair relationship between deltaPI and deltaSV (r2 = 0.34). A deltaPI ≥ 26% predicted a deltaSV > 30% with a sensitivity of 83% and a specificity of 78%  (AUC  =  0.84, 95%CI 0.71-0.93). 24 patients experienced a deltaSV > 30% and subsequently received fluid. Fluid loads induced a 16% increase in SV and a 17% increase in PI, but fluid-induced deltaPI and deltaSV were weakly correlated (r2 = 0.19). In neurosurgical patients, we conclude that deltaPI may be used as a surrogate for deltaSV during LRMs but not during fluid loading. [ABSTRACT FROM AUTHOR]

Fluid administration leads to a significant increase in cardiac output in only half of ICU patients. This has led to the concept of assessing fluid responsiveness before infusing fluid. Pulse pressure variation (PPV), which quantifies the changes in arterial pulse pressure during mechanical ventilation, is one of the dynamic variables that can predict fluid responsiveness. The underlying hypothesis is that large respiratory changes in left ventricular stroke volume, and thus pulse pressure, occur in cases of biventricular preload responsiveness. Several studies showed that PPV accurately predicts fluid responsiveness when patients are under controlled mechanical ventilation. Nevertheless, in many conditions encountered in the ICU, the interpretation of PPV is unreliable (spontaneous breathing, cardiac arrhythmias) or doubtful (low Vt). To overcome some of these limitations, researchers have proposed using simple tests such as the Vt challenge to evaluate the dynamic response of PPV. The applicability of PPV is higher in the operating room setting, where fluid strategies made on the basis of PPV improve postoperative outcomes. In medical critically ill patients, although no randomized controlled trial has compared PPV-based fluid management with standard care, the Surviving Sepsis Campaign guidelines recommend using fluid responsiveness indices, including PPV, whenever applicable. In conclusion, PPV is useful for managing fluid therapy under specific conditions where it is reliable. The kinetics of PPV during diagnostic or therapeutic tests is also helpful for fluid management. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether the respiratory variation in inferior vena cava diameter (DeltaD(IVC)) could be related to fluid responsiveness in mechanically ventilated patients.Design: Prospective clinical study.Setting: Medical ICU of a non-university hospital.Patients: Mechanically ventilated patients with septic shock (n=39).Interventions: Volume loading with 8 mL/kg of 6% hydroxyethylstarch over 20 min.Measurements and Results: Cardiac output and DeltaD(IVC) were assessed by echography before and immediately after the standardized volume load. Volume loading induced an increase in cardiac output from 5.7+/-2.0 to 6.4+/-1.9 L/min (P<0.001) and a decrease in DeltaD(IVC) from 13.8+/-13.6 vs 5.2+/-5.8% (P<0.001). Sixteen patients responded to volume loading by an increase in cardiac output > or =15% (responders). Before volume loading, the DeltaD(IVC) was greater in responders than in non-responders (25+/-15 vs 6+/-4%, P<0.001), closely correlated with the increase in cardiac output (r=0.82, P<0.001), and a 12% DeltaD(IVC) cut-off value allowed identification of responders with positive and negative predictive values of 93% and 92%, respectively.Conclusion: Analysis of DeltaD(IVC) is a simple and non-invasive method to detect fluid responsiveness in mechanically ventilated patients with septic shock. [ABSTRACT FROM AUTHOR]

Purpose: Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Methods: Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3-5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (CO) and third-generation (CO) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). Results: A total of 401 simultaneous measurements of iCO, CO, CO, and CCO were recorded. The mean (95%CI) biases between CO and iCO, CO and iCO, and CCO and iCO were −10 (−15 to −5)% [−0.8 (−1.1 to −0.4) L/min], 0 (−4 to 4)% [0 (−0.3 to 0.3) L/min], and 9 (6-13)% [0.7 (0.5-1.0) L/min], respectively. The percentage errors were 29 (20-37)% for CO, 30 (24-37)% for CO, and 28 (22-34)% for CCO. The difference between iCO and CO was significantly correlated with TSVR ( r = 0.37, p < 0.0001). A very weak ( r = 0.05) relationship was also observed for the difference between iCO and CO. Conclusions: In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software. [ABSTRACT FROM AUTHOR]

Study objective: To assess the value of the global end-diastolic volume (GEDV) evaluated by transpulmonary thermodilution as an indicator of cardiac preload. Design: Prospective clinical study. Setting: Medical ICU of a university hospital (20 beds). Patients: Thirty-six patients with septic shock. Interventions: Volume loading and dobutamine infusion. Measurements and results: Hemodynamic parameters were evaluated in triplicate by the transpulmonary thermodilution technique: (1) before and after 66 fluid challenges in 27 patients, and (2) before and after 28 increases in dobutamine infusion rate in 9 patients. Volume loading induced a significant (p < 0.001) increase in central venous pressure (CVP) from 10 ± 4 to 13 ± 4 mm Hg, in GEDV index from 711 ± 164 to 769 ± 144 mL/m², in stroke volume index (SVI) from 36 ± 12 to 42 ± 12 mL/m², and in cardiac index (CI) from 3.4 ± 1.1 to 3.9 ± 1.2 L/min/m² (mean ± SD). Changes in GEDV index were correlated (r = 0.72, p < 0.001) with changes in SVI, while changes in CVP were not. The increase in SVI was > 15% in 32 of 66 instances (positive response). The preinfusion GEDV index was lower (637 ± 134 mL/m² vs 781 ± 161 mL/m², p < 0.001) in the eases of positive response, and was negatively correlated with the percentage increase in GEDV index (r = -0.65, p < 0.001) and in SVI (r = -0.5, p < 0.001). Dobutamine infusion induced an increase in SVI (32 ± 11 mL/m² vs 35 ± 12 mL/m², p < 0.05) and in CI (2.8 ± 0.6 L/min/m² vs 3.2 ± 0.6 L/min/m², p < 0.001) but no significant change in CVP (13 ± 3 mm Hg vs 13 ± 3 mm Hg) and in GEDV index (823 ± 221 mL/m² vs 817 ± 202 mL/m²). Conclusion: In patients with septic shock, our findings demonstrate that, in contrast to CVP, the transpulmonary thermodilution GEDV index behaves as an indicator of cardiac preload. [ABSTRACT FROM AUTHOR]

Study Objective: To identify and critically review the published peer-reviewed, English-language studies investigating predictive factors of fluid responsiveness in ICU patients.Design: Studies were collected by doing a search in MEDLINE (from 1966) and scanning the reference lists of the articles. Studies were selected according to the following criteria: volume expansion performed in critically ill patients, patients classified in two groups (responders and nonresponders) according to the effects of volume expansion on stroke volume or on cardiac output, and comparison of responder and nonresponder patients' characteristics before volume expansion.Results: Twelve studies were analyzed in which the parameters tested were as follows: (1) static indicators of cardiac preload (right atrial pressure [RAP], pulmonary artery occlusion pressure [PAOP], right ventricular end-diastolic volume [RVEDV], and left ventricular end-diastolic area [LVEDA]); and (2) dynamic parameters (inspiratory decrease in RAP [Delta RAP], expiratory decrease in arterial systolic pressure [Delta down], respiratory changes in pulse pressure [Delta PP], and respiratory changes in aortic blood velocity [Delta Vpeak]). Before fluid infusion, RAP, PAOP, RVEDV, and LVEDA were not significantly lower in responders than in nonresponders in three of five studies, in seven of nine studies, in four of six studies, and in one of three studies, respectively. When a significant difference was found, no threshold value could discriminate responders and nonresponders. Before fluid infusion, Delta RAP, Delta down, Delta PP, and Delta Vpeak were significantly higher in responders, and a threshold value predicted fluid responsiveness with high positive (77 to 95%) and negative (81 to 100%) predictive values.Conclusion: Dynamic parameters should be used preferentially to static parameters to predict fluid responsiveness in ICU patients. [ABSTRACT FROM AUTHOR]

Study objective: To identify and critically review the published peer-reviewed, English-language studies investigating predictive factors of fluid responsiveness in ICU patients. Design: Studies were collected by doing a search in MEDLINE (from 1966) and scanning the reference lists of the articles. Studies were selected according to the following criteria: volume expansion performed in critically ill patients, patients classified in two groups (responders and nonresponders) according to the effects of volume expansion on stroke volume or on cardiac output, and comparison of responder and nonresponder patients' characteristics before volume expansion. Results: Twelve studies were analyzed in which the parameters tested were as follows: (1) static indicators of cardiac preload (fight atrial pressure [RAP], pulmonary artery occlusion pressure [PAOP], fight ventricular end-diastolic volume [RVEDV], and left ventricular end-diastolic area [LVEDA]); and (2) dynamic parameters (inspiratory decrease in RAP [ΔRAP], expiratory decrease in arterial systolic pressure [Δdown], respiratory changes in pulse pressure [ΔPP], and respiratory changes in aortic blood velocity [ΔVpeak]). Before fluid infusion, RAP, PAOP, RVEDV, and LVEDA were not significantly lower in responders than in nonresponders in three of five studies, in seven of nine studies, in four of six studies, and in one of three studies, respectively. When a significant difference was found, no threshold value could discriminate responders and nonresponders. Before fluid infusion, ΔRAP, Adown, ΔPP, and ΔVpeak were significantly higher in responders, and a threshold value predicted fluid responsiveness with high positive (77 to 95%) and negative (81 to 100%) predictive values. Conclusion: Dynamic parameters should be used preferentially to static parameters to predict fluid responsiveness in ICU patients. [ABSTRACT FROM AUTHOR]

Study objective: To investigate whether the respiratory changes in peak velocity (Vpeak) of aortic blood flow could be related to the effects of volume expansion on cardiac index. Design: Prospective clinical study. Setting: Medical ICUs of a university hospital (20 beds) and of a nonuniversity hospital (15 beds). Patients: Nineteen sedated septic shock patients who were receiving mechanical ventilation and who had preserved left ventricular (LV) systolic function. Intervention: Volume expansion. Measurements and results: Analysis of aortic blood flow by transesophageal echocardiography allowed beat-to-beat measurement of Vpeak before and after volume expansion. Maximum values of Vpeak (Vpeakmax) and minimum values of Vpeak (Vpeakmin) were determined over one respiratory cycle. The respiratory changes in Vpeak (ΔVpeak) were calculated as the difference between Vpeakmax and Vpeakmin divided by the mean of the two values and were expressed as a percentage. The indexed LV end-diastolic area (EDAI) and cardiac index were obtained at the end of the expiratory period. The volume expansion-induced increase in cardiac index was ≥ 15% in 10 patients (responders) and < 15% in 9 patients (nonresponders). Before volume expansion, ΔVpeak was higher in responders than in nonresponders (20 ± 6% vs 10 ± 3%; p < 0.01), while EDAI was not significantly different between the two groups (9.7 ± 3.7 vs 9.7 ± 2.4 cm²/m²). Before volume expansion, a ΔVpeak threshold value of 12% allowed discrimination between responders and nonresponders with a sensitivity of 100% and a specificity of 89%. Volume expansion-induced changes in cardiac index closely correlated with the ΔVpeak before volume expansion (r² = 0.83; p < 0.001). Conclusion: Analysis of respiratory changes in aortic blood velocity is an accurate method for predicting the hemodynamic effects of volume expansion in septic shock patients receiving mechanical... [ABSTRACT FROM AUTHOR]

Presents information on a study conducted by researcher C.K. Hofer and others, which demonstrates the superiority of dynamic parameters over static indicators of cardiac preload in predicting fluid responsiveness. Report that in the study left ventricular end-diastolic area (LVEDA) was assessed by echocardiography, global end-diastolic volume (GEDV) was assessed by transpulmonary thermodilution, stroke volume variation was assessed by pulse contour analysis; Observation that preinfusion LVEDA and GEDV values were not related to the hemodynamic effects of fluid administration; Fact that an increase in stroke volume as a result of an increase in preload depends more on the slope of the Frank-Starling curve than on baseline cardiac preload.

Presents a letter to the editor on the issue of influence of tidal volume on stroke volume variation.

Presents a letter to the editor on arterial pressure monitoring in septic shock.

Presents a letter to the editor about transpulmonary thermodilution curves.

Comments on a study published in the December 2002 issue of 'Chest' describing correlations between the findings of portable chest radiographs and fluid balance in critically ill patients. Suggestion that the vascular pedicle width (VPW) is an underutilized tool for the assessment of intravascular volume status; VPW and the wedge pressure of the fluid balance are weak.

Presents a letter to the editor responding Dr. Randolph P. Cole's claims that the time interval between the two peaks of the so-called camel transpulmonary thermodilution curve (with two humps) that was presented in an article in a 2004 issue of "CHEST" is "much too short" to mimic a right-to-left intracardiac shunt.

Presents a letter to the editor about fluid responsiveness in critically ill patients.