Novel Insights into Heart–Lung Interaction and Hemodynamics

Background: The passive leg-raising (PLR) test was developed to predict fluid responsiveness and reduce fluid overload. However, the hemodynamic response of healthy individuals to the PLR test and how it changes during the day, between the morning and evening, after individuals have consumed food and fluids, has not been profoundly explored. This study aimed to compare the systemic hemodynamic changes in healthy individuals between morning and evening PLR tests. Methods: In this study, the PLR test was performed twice a day. The first PLR test was performed between 08h00 and 09h00 in the morning, while the second PLR test was performed between 20h00 and 21h00 in the evening. Hemodynamic parameters were measured using an impedance cardiography monitor, and a cutoff value of a 10% increase in stroke volume (SV) during the PLR test was used to differentiate between preload responders and non-responders. Results: We included 50 healthy volunteers in this study. When comparing the morning and evening PLR test results, we found no PLR-induced differences in heart rate (−3 [−8–2] vs. −2 [−8–4] beats/min, p = 0.870), SV (11 [5–22] vs. 12 [4–20] mL, p = 0.853) or cardiac output (0.7 [0.2–1.3] vs. 0.8 [0.1–1.4] L/min, p = 0.639). We also observed no differences in the proportion of preload responders during the PLR test between the morning and evening (64% vs. 66%, p = 0.99). However, there was a moderate agreement between the two PLR tests (morning and evening) (kappa = 0.429, p = 0.012). There was a moderate correlation between the changes in SV between the two PLR tests (r_s = 0.50, p < 0.001). Conclusion: In young, healthy individuals, we observed no change in the systemic hemodynamic responsiveness to the PLR test between the morning and evening, without restriction of fluid and food intake. Full article

Background: Prevention and treatment of haemodynamic instability and increased intracranial pressure (ICP) in patients with subarachnoid haemorrhage (SAH) is vital. This study aimed to evaluate the effects of protocolised cerebral perfusion pressure (CPP)-guided treatment on morbidity and functional outcome in patients admitted to the intensive care unit (ICU) with SAH. Methods: We performed a retrospective study comparing 37 patients who received standard haemodynamic treatment (control group) with 17 individuals (CPP-guided group) who were on the CPP-guided treatment aimed at maintaining CPP > 70 mmHg using both optimisations of ICP and mean arterial pressure (MAP). Results: MAP, cumulative crystalloid doses and fluid balance were similar in both groups. However, the incidence of delayed cerebral ischaemia was significantly lower in the CPP-guided group (14% vs. 64%, p < 0.01), and functional outcome as assessed by the Glasgow Outcome Scale at 30 days after SAH was improved (29.0% vs. 5.5%, p = 0.03). Conclusions: This preliminary analysis showed that implementing a CPP-guided treatment approach aimed at maintaining a CPP > 70 mmHg may reduce the occurrence of delayed cerebral ischaemia and improve functional outcomes in patients with SAH. This observation merits further prospective investigation of the use of CPP-guided treatment in patients with SAH. Full article