CHEST
Volume 119, Issue 3, March 2001, Pages 867-873
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Clinical Investigations in Critical Care
Respiratory Changes in Aortic Blood Velocity as an Indicator of Fluid Responsiveness in Ventilated Patients With Septic Shock

https://doi.org/10.1378/chest.119.3.867Get rights and content

Study objectives:

To investigate whether the respiratorychanges in peak velocity (Vpeak) of aortic blood flow could be relatedto the effects of volume expansion on cardiac index.

Design:

Prospective clinical study.

Settings:

Medical ICUs of a university hospital (20 beds)and of a nonuniversity hospital (15 beds).

Patients:

Nineteen sedated septic shock patients who were receiving mechanicalventilation and who had preserved left ventricular (LV) systolicfunction.

Intervention:

Volume expansion.

Measurements and results

Analysis of aortic blood flow bytransesophageal 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 overone respiratory cycle. The respiratory changes in Vpeak (ΔVpeak) werecalculated as the difference between Vpeakmax and Vpeakmin divided bythe mean of the two values and were expressed as a percentage. Theindexed LV end-diastolic area (EDAI) and cardiac index were obtained atthe end of the expiratory period. The volume expansion-induced increasein cardiac index was ≥ 15% in 10 patients (responders) and < 15%in 9 patients (nonresponders). Before volume expansion, ΔVpeak washigher in responders than in nonresponders (20 ± 6% vs 10 ± 3%;p < 0.01), while EDAI was not significantly different between thetwo groups (9.7 ± 3.7 vs 9.7 ± 2.4cm2/m2). Before volume expansion, a ΔVpeakthreshold 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 correlatedwith the ΔVpeak before volume expansion(r2 = 0.83; p < 0.001).

Conclusion:

Analysis of respiratory changes in aortic bloodvelocity is an accurate method for predicting the hemodynamic effectsof volume expansion in septic shock patients receiving mechanicalventilation who have preserved LV systolic function.

Section snippets

Materials and Methods

The protocol was approved by the institutional review board forhuman subjects of our institutions, and written informed consent wasobtained from each patient's next of kin.

Results

The 19 patients studied had clear evidence of sepsis (abdominalsepsis, 10 patients; bacterial pneumonia, 9 patients). All patientsreceived inotropic and vasopressor drugs. Thirteen patients receivedepinephrine (0.3 to 2.5μg/kg/min; mean dose, 1.4 ± 0.6μg/kg/min), 6 patients received dopamine (12 to 20μg/kg/min; meandose, 16 ± 4μg/kg/min), and 11 patients received dobutamine (5μg/kg/min). Transesophageal echocardiography was performed between 12and 72 h after the diagnosis of septic shock.

Discussion

In patients with septic shock who are receiving mechanicalventilation, our results demonstrate a strong relationship between ΔVpeak and the effects of volume expansion on cardiac output. Theystrongly suggest that ΔVpeak before volume expansion is an accurateindicator of fluid responsiveness while EDAI is of little value inpredicting the effects of volume expansion on cardiac output.

Volume expansion is proposed as a first-line therapy for septic shockin order to improve hemodynamics.16 Both the

ACKNOWLEDGMENT

The authors thank Dr. Denis Pellerin and SuzanneKelly for helpful discussion.

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