Incoherence between Systemic Hemodynamic and Microcirculatory Response to Fluid Challenge in Critically Ill Patients

Abstract

Background: The aim of the study was to assess the coherence between systemic hemodynamic and microcirculatory response to a fluid challenge (FC) in critically ill patients. Methods: We prospectively collected data in patients requiring a FC whilst cardiac index (CI) and microcirculation were monitored. The sublingual microcirculation was assessed using the incident dark field (IDF) CytoCam device (Braedius Medical, Huizen, The Netherlands). The proportion of small perfused vessels (PPV) was calculated. Fluid responders were defined by at least a 10% increase in CI during FC. Responders according to changes in microcirculation were defined by at least 10% increase in PPV at the end of FC. Cohen’s kappa coefficient was measured to assess the agreement to categorize patients as “responders” to FC according to CI and PPV. Results: A total of 41 FC were performed in 38 patients, after a median time of 1 (0–1) days after ICU admission. Most of the fluid challenges (39/41, 95%) were performed using crystalloids and the median total amount of fluid was 500 (500–500) mL. The main reasons for fluid challenge were oliguria (n = 22) and hypotension (n = 10). After FC, CI significantly increased in 24 (58%) cases; a total of 19 (46%) FCs resulted in an increase in PPV. Both CI and PPV increased in 13 responders and neither in 11; the coefficient of agreement was only 0.21. We found no correlation between absolute changes in CI and PPV after fluid challenge. Conclusions: The results of this heterogenous population of critically ill patients suggest incoherence in fluid responsiveness between systemic and microvascular hemodynamics; larger cohort prospective studies with adequate a priori sample size calculations are needed to confirm these findings.

Hemodynamic Monitoring in Sepsis—A Conceptual Framework of Macro- and Microcirculatory Alterations

“…Nonetheless, progressive stages exhibit both endothelial dysfunction and cytopathic hypoxia [ 14 ]. The former marks a new circulatory status where macrocirculation and microcirculation become uncoupled (i.e., hemodynamic incoherence), meaning that tissue perfusion may not improve or may even worsen after a systemic flow increase [ 15 ]. The latter potentially signals a second level of uncoupling between the microcirculation and the mitochondrial respiratory chain complexes.…”

“…Thirdly, prediction of fluid responsiveness allows no assumptions regarding the safety, longevity of intravascular response, and optimum rate (e.g., bolus versus continuous) of fluid administration. Lastly, macrocirculatory responsiveness does not guarantee microcirculatory responsiveness, hence the importance of incorporating microcirculatory variables into clinical practice [ 15 ].…”

“…Early but not late sepsis showed marked microcirculatory improvement following fluid administration, a result that remained independent of the type of fluid (i.e., crystalloid versus 4% albumin) and global circulatory effects [ 104 ]. Two other studies looked at the macro-microcirculatory coherence following a volume challenge in the early sepsis and showed conflicting results, probably reflecting patients with different severity of illness [ 15 , 105 ].…”

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

“…Therefore, physiologic approaches are needed that allow the monitoring of the hemodynamic parameters and allow optimal oxygen delivery in shock resuscitation [43]. The importance of this principle is illustrated in the use of fluid challenge in critically ill patients [44]. Where there can be limited correlation between absolute changes in cardiac macrocirculation and small diameter vessels (microcirculation) in response to administration of a fluid challenge.…”

A novel non-invasive method of measuring microcirculatory perfusion and blood velocity in infants: a pilot study

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