Please see Bibliography of References for a list of abstracts, manuscripts and posters.

Microvascular Dysfunction

Effects of fluid resuscitation on microcirculation assessed by near infrared spectroscopy in septic patients

Georger JF, Chaari A, Richard C, Teboul JL. Int Care Med. 2008;34(Supp 1):S66. Abstract 0247.

Introduction: The near infrared spectroscopy (NIRS) assesses the haemoglobin saturation in the tissue (StO₂). Induction of transient ischemia followed by hyperaemia (forearm occlusion and release) provides additional information on the ability of microvessels to be recruited through the analysis of the StO₂ re-ascension slope.

Objective: To examine whether saline infusion aimed to improve systemic haemodynamics in septic shock patients was able to affect regional microcirculation assessed by NIRS indices.

Methods: We included 35 patients with septic shock equipped with a PiCCO’’ monitoring system. The thenar muscle StO₂ was continuously measured with Inspectra’’ model 650 (Hutchinson Technology) before and during pneumatic arm cuff inflation (until StO₂ by 40% is reached) and after deflation, which allowed calculating the StO₂ re-ascension slope (slope).

Mean arterial pressure (MAP), cardiac index (CI), central venous oxygen saturation (ScvO₂) and StO₂ measurements were performed before and after infusion of 500 ml of saline. Two groups of patients were identified. In 20 patients (responders) the CI increased > 15% after saline infusion, while in 15 patients (non-responders) CI did not increase > 15%. We also collected MAP, StO₂ and the slope in 15 healthy volunteers.

Results: In healthy volunteers the MAP was 89 mmHg (68–101), StO₂ was 82% (75–90) and the slope was 2.29%/s (1.46–3.36). In responders saline infusion increased (p < 0.05) MAP from 74 (40–118) to 85 mmHg (60–112), CI from 2.37 (1.43–4.35) to 3.02 L/min/m² (2.19–5.66), ScvO₂ from 68 (26–82) to 71% (39–88) and the slope from 0.86 (0.24–2.14) to 1.07%/s (0.40–2.83). In this sub-group StO₂ did not change from 76% (50–91) to 76% (51–91). In non-responders, no change the studied parameters was observed after fluid infusion: MAP: from 69 (60–101) to 77 mmHg (48–113), CI: from 3.46 (1.33–5.66) to 3.36 L/min/m² (1.44–6.18), ScvO₂: from 73 (55–77) to 72% (57–79), the slope: from 1.34%/s (0.52–4.3) to 1.46%/s (0.36–4.4), StO₂: from 81 (70–92) to 79% (70–90).

Conclusion: In responders, the increase in CI in response to saline was associated with an increase in ScvO₂ and MAP but not in StO₂. However the slope was improved suggesting recruitment of microvessels with fluid infusion. In non responder saline infusion did not change the studied values (macrocirculatory as well as NIRS parameters).