Monitoring tissue blood flow and oxygenation: a brief review of emerging techniques.

This article describes promising emerging technologies developed for measuring tissue-level oxygenation or perfusion, each with its own inherent limitations. The end user must understand what the instrument measures and how to interpret the readings. Optical monitoring using near-infrared spectrometry, Doppler shift, and videomicroscopy are discussed in terms of their application at the tissue level.

Basic concepts of hemorheology in microvascular hemodynamics.

Blood rheology, or hemorheology, involves the flow and deformation behavior of blood and its formed elements (ie, erythrocytes, leukocytes, platelets). The adequacy of blood flow to meet metabolic demands through large circulatory vessels depends highly on vascular control mechanisms. However, the extent to which rheologic properties of blood contribute to vascular flow resistance, particularly in the microcirculation, is becoming more appreciated.

The physiologic role of erythrocytes in oxygen delivery and implications for blood storage.

Erythrocytes are not just oxygen delivery devices but play an active metabolic role in modulating microvascular blood flow. Hemoglobin and red blood cell morphology change as local oxygen levels fall, eliciting the release of adenosine triphosphate and nitric oxide to initiate local vasodilation. Aged erythrocytes undergo physical and functional changes such that some of the red cell's most physiologically helpful attributes are diminished.

Effects of body position on resting lung volume in overweight and mildly to moderately obese subjects.

Introduction: A partial sitting position has been reported to increase functional residual capacity (FRC) in lean subjects, whereas FRC does not change with position in the morbidly obese. The effects of positioning in the subgroup of overweight and mildly to moderately obese subjects have not been examined. We hypothesized that a change in FRC may be related to adipose tissue distribution.