November 29, 2025
Background: Capillary tortuosity is a morphological variant of the microcirculation. However, the mechanisms by which tortuous vessels meet metabolic requirements in health and disease remain unknown. Previous studies have shown that capillary tortuosity score (CTS) is significantly higher in patients with septic shock than in individuals with normal physiology and is associated with the alveolar-to-arterial oxygen (A-a O₂) gradient and oxygen debt.
Objective: To investigate the characteristics of the magnetic fields in the sublingual microcirculation of individuals with normal physiology and patients with septic shock.
Methods: Systemic hemodynamics were recorded, and sublingual microcirculation was monitored using sidestream dark field (SDF+) imaging. The number of capillary red blood cells (NRBC), the intensity of the magnetic field of a red blood cell (HRBC), the intensity of the magnetic field of each capillary (HCAP), and the intensity with which the magnetic field of a capillary acts on a red blood cell (FCAP) were calculated.
Results: Significant differences in macro- and microhemodynamic variables were observed between the two groups. Although NRBC was significantly higher in individuals with normal physiology [87.4 (87.12) vs. 12.23 (6.9)], HRBC was significantly stronger in patients with septic shock [5.9 × 10⁻¹⁶ (6.9 × 10⁻¹⁶) A m⁻¹ vs. 1.6 × 10⁻¹⁵ (1.4 × 10⁻¹⁵) A m⁻¹]. No significant differences were observed in HCAP [2.16 × 10⁻¹⁴ (2.17 × 10⁻¹⁴) A m⁻¹ vs. 1.34 × 10⁻¹⁴ (1.23 × 10⁻¹⁴) A m⁻¹] or FCAP [1.66 × 10⁻²⁴ (3.36 × 10⁻²⁴) A m⁻¹ vs. 6.44 × 10⁻²⁵ (1.1 × 10⁻²⁴) A m⁻¹] between the two groups. In patients with septic shock, HRBC was associated with the De Backer score (rho = -0.608) and venous-arterial carbon dioxide difference (rho = 0.569). HCAP was associated with convective oxygen flow (rho = 0.790) and oxygen extraction ratio (rho = -0.596). FCAP was significantly associated with base deficit (rho = 0.701), A-a O₂ gradient (rho = 0.658), and oxygen debt (rho = -0.769).
Conclusions: Despite microcirculatory impairment in patients with septic shock, HRBC was significantly stronger than in individuals with normal physiology. HCAP and FCAP were comparable between the two groups. Tortuous vessels may function as biomagnetic coils that amplify red blood cell-induced magnetic fields, thereby enhancing perfusion and oxygenation of adjacent tissues.
Keywords: septic shock; microcirculation; magnetic field; cardiovascular dynamics; circulatory dynamics; hemodynamics; translational physiology; applied physiology; critical care medicine; anesthesiology.
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