Recombinant activated protein C treatment improves tissue perfusion and oxygenation in septic patients measured by near-infrared spectroscopy

Abstract

IntroductionThe purpose was to test the hypothesis that muscle perfusion, oxygenation, and microvascular reactivity would improve in patients with severe sepsis or septic shock during treatment with recombinant activated protein C (rh-aPC) (n = 11) and to explore whether these parameters are related to macrohemodynamic indices, metabolic status or Sequential Organ Failure Assessment (SOFA) score. Patients with contraindications to rh-aPC were used as a control group (n = 5).Materials and methodsPatients were sedated, intubated, mechanically ventilated, and hemodynamically monitored with the PiCCO system. Tissue oxygen saturation (StO2) was measured using near-infrared spectroscopy (NIRS) during the vascular occlusion test (VOT). Baseline StO2 (StO2 baseline), rate of decrease in StO2 during VOT (StO2 downslope), and rate of increase in StO2 during the reperfusion phase were (StO2 upslope) determined. Data were collected before (T0), during (24 hours (T1a), 48 hours (T1b), 72 hours (T1c) and 96 hours (T1d)) and 6 hours after stopping rh-aPC treatment (T2) and at the same times in the controls. At every assessment, hemodynamic and metabolic parameters were registered and the SOFA score calculated.ResultsThe mean ± standard deviation Acute Physiology and Chronic Health Evaluation II score was 26.3 ± 6.6 and 28.6 ± 5.3 in rh-aPC and control groups, respectively. There were no significant differences in macrohemodynamic parameters between the groups at all the time points. In the rh-aPC group, base excess was corrected (P < 0.01) from T1a until T2, and blood lactate was significantly decreased at T1d and T2 (2.8 ± 1.3 vs. 1.9 ± 0.7 mmol/l; P < 0.05). In the control group, base excess was significantly corrected at T1a, T1b, T1c, and T2 (P < 0.05). The SOFA score was significantly lower in the rh-aPC group compared with the controls at T2 (7.9 ± 2.2 vs. 12.2 ± 3.2; P < 0.05). There were no differences between groups in StO2 baseline. StO2 downslope in the rh-aPC group decreased significantly at all the time points, and at T1b and T2 (-16.5 ± 11.8 vs. -8.1 ± 2.4%/minute) was significantly steeper than in the control group. StO2 upslope increased and was higher than in the control group at T1c, T1d and T2 (101.1 ± 62.1 vs. 54.5 ± 23.8%/minute) (P < 0.05).ConclusionsTreatment with rh-aPC may improve muscle oxygenation (StO2 baseline) and reperfusion (StO2 upslope) and, furthermore, rh-aPC treatment may increase tissue metabolism (StO2 downslope). NIRS is a simple, real-time, non-invasive technique that could be used to monitor the effects of rh-aPC therapy at microcirculatory level in septic patients.

Tissue saturation measurement - exciting prospects, but standardisation and reference data still needed

“…Furthermore, it seems that VOT reflects severity of illness and is sensitive to intervention with activated protein C [8,11]. According to the current study it may also have a role in guiding resuscitation and optimisation of haemodynamics.…”

From Macrohemodynamic to the Microcirculation

“…In a prospective observational open study, Donati et al measured the tissue oxygen saturation (StO2) using the near infrared spectroscopy during a vascular occlusion test and demonstrated an improvement in both the StO2 downslope and upslope in patients treated with aPC, unlike the controls, reflecting an improved microvascular reactivity [46]. …”

C reactive protein: impact on peripheral tissue oxygenation and perfusion in neonates

“…In adults, NIRS has shown to be a useful tool in assessing compromised peripheral tissue perfusion and circulation in patients with sepsis 6 15…”