Hemodynamic Effect of Different Doses of Fluids for a Fluid Challenge: A Quasi-Randomized Controlled Study

Abstract

Objective: The objectives of this study are to determine what is the minimal volume required to perform an effective fluid challenge (FC) and to investigate how different doses of intravenous fluids in a FC affect the changes in cardiac output and the proportion of responders and non-responders.Design: quasi-randomised controlled trial. Setting: Cardiothoracic intensive care unit, tertiary university hospitalPatients: 80 Post-cardiac surgery patients.Intervention: intravenous infusion of 1, 2, 3 or 4 mL/Kg (body weight) of crystalloid over 5 minutes.Measurements: Mean systemic filling pressure measured using the transient stop-flow arm arterial-venous equilibrium pressure (Pmsf-arm), arterial and central venous pressure (CVP), cardiac output (CO; LiDCOplus, LiDCO, Cambridge, UK) and heart rate. Results:The groups were well matched with respect to demographic and baseline physiological variables.The proportion of responders increased from 20% in the group of 1mL/kg to 65% in the group of 4 mL/kg (p = 0.04). The predicted minimal volume required for a FC was between 321 to 509 mL. Only 4 mL/Kg increase Pmsf-arm beyond the limits of precision and was significantly associated with a positive response (OR 7.73, 95% CI 1.78 to 31.04). Conclusion:The doses of fluids used for a FC modify the proportions of responders in postoperative patients. A dose of 4 ml/Kg increases Pmsf-arm and reliably detects responders and non-responders.

The SEP-1 quality mandate may be harmful: How to drown a patient with 30 mL per kg fluid!

“…the increase in mean circulating filling pressure (MSFP) must be greater than the increase in CVP [15]. In a dose titration study performed in post cardiac surgery patients, the authors demonstrated that a fluid bolus of about 300 mL is required to reliably increase MCFP [20]. In septic patients with an increased unstressed volume it is likely that a 500 mL fluid bolus would achieve the same effect.…”

The stop‐flow arm equilibrium pressure in preoperative patients: Stressed volume and correlations with echocardiography

“…The higher heart rate and the numerically increased MAP in patients demonstrating a decrease in P arm compared to patients in whom P arm increased is consistent with increased baseline sympathetic activity that could have been attenuated by the fluid bolus. The variable response of P arm to fluid loading has been reported in post‐cardiac surgery patients, although fluid volumes similar to the 500 mL of this study generally increased P arm . The dynamic responses in vascular compliance illustrate the complexity of predicting volume responsiveness in patients and highlights the importance of P arm and its interpretation to evaluate and quantify the intravascular volume state.…”

Stroke Volume Variation and Stroke Volume Index Can Predict Fluid Responsiveness after Mini-Volume Challenge Test in Patients Undergoing Laparoscopic Cholecystectomy

“…Although the operational conditions of laparoscopic cholecystectomy includes pneumoperitoneum and the reverse Trendelenburg position and both can cause an excessive preload-dependent state, considering laparoscopic cholecystectomy is a less-invasive surgery with minimal bleeding risks, the volume for conventional fluid responsiveness test can be relatively large and may cause a volume overload postoperatively. Although the mini-volume test uses relatively small volumes, it has been used in many previous studies and showed good results [17][18][19].…”