Systemic hemodynamic responsiveness to passive leg raise test

Abstract

Introduction The passive leg raise (PLR) test has been developed as a strategy to predict fluid responsiveness and has the potential to reduce fluid administration (1). However, it is not profoundly explored how healthy individuals physiologically respond to PLR test and how it changes during the day, compared morning to the evening when individuals have consumed fluids. Aim To compare systemic hemodynamic changes of healthy individuals during the PLR test in the morning and in the evening. Methods The trial was conducted at LUHS Hospital Kaunas Clinics Department of Intensive care, where healthy volunteers were examined. Criteria for inclusion in the trial group: age of the volunteers from 18 and above, no history of chronic illness, healthy at the present time. Data was collected in the morning and in the evening. Volunteers were instructed to not consume any food, beverages or tobacco products before the test in the morning. A passive leg raising test was performed and systemic hemodynamic changes were registered by non-invasive impedance cardiography monitor before and after the PLR test. An increase in stroke volume (SV) ≥ 15% was considered a positive test result and a person considered being a fluid responder accordingly Data is presented as median (interquartile range). Results were considered statistically significant when p<0.05. Results The study involved 50 volunteers, 16 of them were males (32%) and 34 were females (68%). The age median of the participants was 23 years. Body mass index was 21.8 (20.0 – 23.8) kg/m2. The median heart rate in the morning and in the evening before the PLR test was not statistically significant. We found a significant rise of the baseline mean arterial pressure in the morning 92 (88 – 100) mmHg and in comparison, in the evening 96 (92 – 103) mmHg (p=0.004). The analysis also showed a significant increase in cardiac output in the morning and in the evening before the PLR test: 5.9 (5.3 – 6.6) l/min vs. 6.3 (5.4 – 7.1) l/min, p=0.033. There was no significant change in SV as well in the responders proportions compared PLR test performed in the morning to evening. Conclusions We observed no change in systemic hemodynamic responsiveness to PLR test during day in young healthy individuals. However, some physiological changes, unaffected by PLR test, in systemic hemodynamics have been observed, which may be related to participants daily routine.