Applicability of stroke volume variation in patients of a general intensive care unit: a longitudinal observational study

Abstract

Sinus rhythm (SR) and controlled mechanical ventilation (CV) are mandatory for the applicability of respiratory changes of the arterial curve such as stroke volume variation (SVV) to predict fluid-responsiveness. Furthermore, several secondary limitations including tidal volumes <8 mL/kg and SVV-values within the "gray zone" of 9-13% impair prediction of fluid-responsiveness by SVV. Therefore, we investigated the prevalence of these four conditions in general ICU-patients. This longitudinal observational study analyzed a prospectively maintained haemodynamic database including 4801 transpulmonary thermodilution and pulse contour analysis measurements of 278 patients (APACHE-II 21.0 ± 7.4). The main underlying diseases were cirrhosis (32%), sepsis (28%), and ARDS (17%). The prevalence of SR and CV was only 19.4% (54/278) in the first measurements (primary endpoint), 18.8% (902/4801) in all measurements and 26.5% (9/34) in measurements with MAP < 65 mmHg and CI < 2.5 L/min/m and vasopressor therapy. In 69.1% (192/278) of the first measurements and in 65.9% (3165/4801) of all measurements the patients had SR but did not have CV. In 1.8% (5/278) of the first measurements and in 2.5% (119/4801) of all measurements the patients had CV but lacked SR. In 9.7% (27/278) of the first measurements and in 12.8% (615/4801) of all measurements the patients did neither have SR nor CV. Only 20 of 278 (7.2%) of the first measurements and 8.2% of all measurements fulfilled both major criteria (CV, SR) and both minor criteria for the applicability of SVV. The applicability of SVV in ICU-patients is limited due to the absence of mandatory criteria during the majority of measurements.

Impact of deep breathing on predictability of stroke volume variation in spontaneous breathing patients

“…The concept of assessing fluid responsiveness was initially adopted in patients receiving mechanical ventilation, without spontaneous breathing, with a tidal volume exceeding 7 mL/kg, and a regular heart rate rhythm. These criteria are not applicable to about 90% of patients in the intensive care unit, which therefore limits the use of dynamic indices in the peri‐operative period . Previous studies have reported that various interventions improved the reliability of dynamic indices even in patients with low tidal volume ventilation.…”

“…These criteria are not applicable to about 90% of patients in the intensive care unit, which therefore limits the use of dynamic indices in the peri-operative period. 8 19 However, these studies were conducted in mechanically ventilated patients. In particular, the presence of spontaneous breathing is considered to be a major limitation to the application of dynamic indices, which have clinically unacceptable reliability in patients with spontaneous breathing.…”

“…However, these dynamic indices have performed poorly when used with lower tidal volume (<8 ml/kg) or lower driving airway pressure (<20 cm H 2 O) . As lung protective ventilation with a lower tidal volume (6‐7 mL/kg) and positive end‐expiratory pressure (PEEP) (5‐10 cm H 2 O) is commonly used in the peri‐operative period, the usefulness of dynamic indices to discriminate the fluid responders is limited, and thus their applicability in daily clinical practice is reduced …”

“…6,7 As lung protective ventilation with a lower tidal volume (6-7 mL/kg) and positive end-expiratory pressure (PEEP) (5-10 cm H 2 O) is commonly used in the peri-operative period, the usefulness of dynamic indices to discriminate the fluid responders is limited, and thus their applicability in daily clinical practice is reduced. 8 Positive-pressure ventilation induces cyclical changes in intrathoracic pressure, which can have an impact on the right and left ventricular preload. If the alternation of intrathoracic pressure at a low tidal volume is too small, the magnitude of respiratory variations in ventricular preload would be reduced.…”

Update on the assessment of fluid responsiveness

“…However, certain conditions, including arrhythmias and spontaneous breathing, impose some limitations for the clinical use of dynamic indices [14]. In particular, these indices have poor predictability for fluid responsiveness in patients with low tidal volumes (< 8 ml/kg) or low driving airway pressures (< 20 cm H 2 O) [15,16].…”