Monitoring of skeletal muscle oxygenation using near-infrared spectroscopy during abdominal aortic surgery

This article provides a snapshot of muscle near-infrared spectroscopy (NIRS) at the end of 2010 summarizing the recent literature, offering the present status and perspectives of the NIRS instrumentation and methods, describing the main NIRS studies on skeletal muscle physiology, posing open questions and outlining future directions. So far, different NIRS techniques (e.g. continuous-wave (CW) and spatially, time- and frequency-resolved spectroscopy) have been used for measuring muscle oxygenation during exercise. In the last four years, approximately 160 muscle NIRS articles have been published on different physiological aspects (primarily muscle oxygenation and haemodynamics) of several upper- and lower-limb muscle groups investigated by using mainly two-channel CW and spatially resolved spectroscopy commercial instruments. Unfortunately, in only 15 of these studies were the advantages of using multi-channel instruments exploited. There are still several open questions in the application of NIRS in muscle studies: (i) whether NIRS can be used in subjects with a large fat layer; (ii) the contribution of myoglobin desaturation to the NIRS signal during exercise; (iii) the effect of scattering changes during exercise; and (iv) the effect of changes in skin perfusion, particularly during prolonged exercise. Recommendations for instrumentation advancements and future muscle NIRS studies are provided.

Download Full-text

Modeling oxygenation in venous blood and skeletal muscle in response to exercise using near-infrared spectroscopy

Journal of Applied Physiology ◽

10.1152/japplphysiol.91102.2008 ◽

2009 ◽

Vol 106 (6) ◽

pp. 1858-1874 ◽

Cited By ~ 34

Author(s):

Nicola Lai ◽

Haiying Zhou ◽

Gerald M. Saidel ◽

Martin Wolf ◽

Kevin McCully ◽

...

Keyword(s):

Skeletal Muscle ◽

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Oxygen Transport ◽

Near Infrared ◽

Muscle Oxygenation ◽

Dynamic Responses ◽

External Respiration ◽

Model Simulations ◽

Nirs Signal

Noninvasive, continuous measurements in vivo are commonly used to make inferences about mechanisms controlling internal and external respiration during exercise. In particular, the dynamic response of muscle oxygenation ([Formula: see text]) measured by near-infrared spectroscopy (NIRS) is assumed to be correlated to that of venous oxygen saturation (SvO2) measured invasively. However, there are situations where the dynamics of [Formula: see text] and SvO2 do not follow the same pattern. A quantitative analysis of venous and muscle oxygenation dynamics during exercise is necessary to explain the links between different patterns observed experimentally. For this purpose, a mathematical model of oxygen transport and utilization that accounts for the relative contribution of hemoglobin (Hb) and myoglobin (Mb) to the NIRS signal was developed. This model includes changes in microvascular composition within skeletal muscle during exercise and integrates experimental data in a consistent and mechanistic manner. Three subjects (age 25.6 ± 0.6 yr) performed square-wave moderate exercise on a cycle ergometer under normoxic and hypoxic conditions while muscle oxygenation (Coxy) and deoxygenation (Cdeoxy) were measured by NIRS. Under normoxia, the oxygenated Hb/Mb concentration (Coxy) drops rapidly at the onset of exercise and then increases monotonically. Under hypoxia, Coxy decreases exponentially to a steady state within ∼2 min. In contrast, model simulations of venous oxygen concentration show an exponential decrease under both conditions due to the imbalance between oxygen delivery and consumption at the onset of exercise. Also, model simulations that distinguish the dynamic responses of oxy-and deoxygenated Hb (HbO2, HHb) and Mb (MbO2, HMb) concentrations (Coxy = HbO2 + MbO2; Cdeoxy = HHb + HMb) show that Hb and Mb contributions to the NIRS signal are comparable. Analysis of NIRS signal components during exercise with a mechanistic model of oxygen transport and metabolism indicates that changes in oxygenated Hb and Mb are responsible for different patterns of [Formula: see text] and SvO2 dynamics observed under normoxia and hypoxia.

Download Full-text