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Orthogonal polarization spectral imaging revealed no major changes of microvascular perfusion during uncomplicated hypothermic CPB. The slightly reduced functional capillary density during CPB may be caused by several factors all present during CPB, including hypothermia, the artificial extracorporeal perfusion, surgical trauma, hemodilution, and inflammatory reaction. The current data do not allow differentiation between the effects of those possible causes.

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The decreased CFC in response to sevoflurane may result in less extravasation of fluids into the interstitial space, thereby reducing intraoperative fluid requirements. These data suggest that sevoflurane may be the preferred anesthetic agent in subjects susceptible to large intraoperative fluid shifts.

ABSTRACT:In adults with severe sepsis, the disturbances of the sublingual microcirculation can be quantified with orthogonal polarization spectral imaging. We investigated the cutaneous microcirculation of preterm infants with proven infection (PosInf) and with suspected but unproven infection (NegInf). In 25 infants, orthogonal polarization spectral images were obtained daily, videos of the images were blinded, and analyzed off-line. Functional small vessel density (FSVD) was prospectively calculated from day 3 to day 30 of life. There were 17 episodes of proven and nine episodes of suspected but unproven nosocomial late onset infection. Four infants remained healthy. The data were analyzed for the 5 d before the start of antibiotics (day Ϫ5 until day Ϫ1). FSVD varied widely, but in the PosInf-group, we found a 10% decline from day Ϫ5 to day Ϫ1 (p ϭ 0.013). There was no significant change over time in the NegInfgroup (p ϭ 0.58). Thus, in infants with proven infection, FSVD decreases already 1 d before changes in laboratory parameters. However, these changes in FSVD during infection are not represented by absolute values, but must be identified by daily intraindividual observation. (Pediatr Res 66: 461-465, 2009) V ery low-birth weight infants are at increased risk for episodes of nosocomial infection, which contributes significantly to mortality and morbidity (1). Early diagnosis and prompt administration of appropriate antibiotics are crucial to improve outcome but clinical signs of infection are very unspecific. White blood cell count has not been shown to improve early diagnosis; C-reactive protein (CRP) is quite specific but not very sensitive for neonatal infection. Cytokines such as interleukine (IL)-6 increase early in neonatal infection before the rise of CRP, and the combination of both increases sensitivity and specificity (2). The need for early treatment in combination with nonspecific clinical signs leads to significant iatrogenic blood loss (3) and an increased exposure to antibiotics.Most clinical signs of infection such as change of skin color, a prolonged capillary filling time, and temperature instability are caused by altered microcirculation. Changes in microcirculation play an important role in the development of septic organ dysfunction (4,5) and the severity of change may even predict outcome (6). Improved technology has made observation and quantification of microcirculatory parameters possible. One of the most promising instrumentation in the regard is the orthogonal polarization spectral (OPS) imaging technique, which allows new insights in the human microcirculation and semiquantified assessment. This method provides high-resolution images of the microvascular architecture to a depth of 1 mm. OPS has been validated by multiple studies in animals and humans (7,8). Using OPS Sakr et al. (6) recently found an association between microcirculatory alterations, organ dysfunction, and death in patients with septic shock. We have previously shown that OPS imaging and measurement of small vess...

We present a newly developed electromechanical sensor with automated calibration for strain-gauge plethysmography (filtrass) and compare it to a conventional mercury-in-Silastic strain-gauge plethysmograph (MSG). Fluid filtration capacity (K(f)) and isovolumetric venous pressure (Piv) of the limb were assessed noninvasively with both devices in 29 healthy volunteers. We found significantly higher K(f) and Piv values with MSG [4.6 +/- 2.0 x 10(-3) ml. min(-1). mmHg(-1). 100 ml tissue(-1) (K(f) units; K(f)U) and 21.2 +/- 8.1 mmHg for Pvi], than with filtrass, giving values of 3.1 +/- 0.8 K(f)U and 15.1 +/- 7.1 mmHg. Because K(f) and Piv are profoundly influenced by the calibration, we investigated the quality of the calibration signal and its impact on the obtained values. We could show that the reproducibility of repeated calibrations was higher with filtrass (58% lower mean +/- SD). The data were grouped according to the quality of calibration, and we found no significant difference in K(f) and Piv between filtrass (3.0 +/- 0.7 K(f)U and 15.9 +/- 6.9 mmHg, respectively) and MSG with good calibration signal (3.3 +/- 0. 8 K(f)U and 18.6 +/- 7.1 mmHg, respectively; no significant difference). However, we obtained significantly higher MSG values (5. 6 +/- 2.0 K(f)U and 23.1 +/- 8.4 mmHg, respectively; P < 0.001) in the group with a bad calibration signal. We suggest that the filtrass sensor, which performs an automatic, standardized calibration procedure and shows a linear signal response to stretch, gives highly reproducible and reliable results and thus is more suitable for routine application.