PERFUSION BEYOND ARTERIAL PRESSURE IN THE PERIOPERATIVE PERIOD: FROM MACRODYNAMICS TO MICRODYNAMICS AND THE EFFECTIVE PERFUSION GRADIENT

• DOI: https://doi.org/10.22533/at.ed.15953126020110

• Palavras-chave: hemodynamic monitoring, tissue perfusion, microcirculation.

• Keywords: hemodynamic monitoring, tissue perfusion, microcirculation

• Abstract:

  Mean arterial pressure (MAP) has traditionally been used as the main target for perioperative hemodynamic management; however, its normalization does not guarantee effective tissue perfusion. Perfusion occurs at the microvascular level and depends on the interaction between pressure, flow, capillary distribution, and the effective perfusion gradient, defined by the difference between arterial inlet pressure and venous or compartmental outlet pressures.
  In the perioperative period, multiple factors such as anesthesia, surgical inflammation, vasoplegia, hemodilution, use of vasopressors, and positive pressure ventilation can cause a loss of hemodynamic coherence, in which acceptable macrodynamic parameters coexist with persistent tissue hypoperfusion. This discordance explains the onset of organ dysfunction, particularly renal dysfunction, even in the presence of a MAP considered adequate.
  The assessment of perfusion requires a multimodal approach, integrating clinical and metabolic markers of microperfusion (capillary refill time, perfusion index, lactate, and diuresis), along with imaging tools such as point-of-care ultrasound (POCUS) to assess cardiac function, venous congestion, and compartment pressures. In this context, increased central venous pressure or intra-abdominal pressure can significantly reduce the perfusion gradient and compromise effective oxygen delivery.
  An integrative perioperative approach is proposed, based on a sequential assessment of macrodynamics, microdynamics, and effective perfusion gradient, followed by interventions guided by hemodynamic phenotype and dynamic reassessment. This paradigm shift promotes personalized, physiologically oriented hemodynamic management focused on actual perfusion, with the potential to optimize outcomes and reduce perioperative organ dysfunction.