What question did this study set out to answer?

To evaluate a minimally invasive indicator-dilution method combining near-infrared spectroscopy and indocyanine green for quantifying respiratory muscle blood flow across varying levels of ventilation in conscious humans.

January 25, 2008Journal of Applied Physiology

Human respiratory muscle blood flow measured by near-infrared spectroscopy and indocyanine green

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Why the study?

Does the NIRS-ICG technique provide a feasible index of respiratory muscle blood flow at different levels of ventilation in conscious humans?

Key Points

To evaluate a minimally invasive indicator-dilution method combining near-infrared spectroscopy and indocyanine green for quantifying respiratory muscle blood flow across varying levels of ventilation in conscious humans.
Assessed 5 conscious human subjects during resting breathing and three separate 5-minute bouts of constant isocapnic hyperpnea at 27.1 ± 3.2%, 56.0 ± 6.1%, and 75.9 ± 5.7% of maximum minute ventilation.
Quantified respiratory muscle blood flow (intercostal space/costal diaphragm) and inactive vastus lateralis flow using NIRS paired with intravenous bolus injections of indocyanine green dye, while measuring cardiac output and transdiaphragmatic pressures.
Respiratory muscle blood flow progressively increased from 9.9 ± 0.6 ml·100ml⁻¹·min⁻¹ at rest to 14.8 ± 2.7, 29.9 ± 5.8, and 50.1 ± 12.5 ml·100ml⁻¹·min⁻¹ during graded hyperpnea, while control vastus lateralis blood flow remained constant (10.4 ± 1.4 to 12.2 ± 1.8 ml·100ml⁻¹·min⁻¹).
Respiratory muscle blood flow strongly and significantly correlated with cardiac output (r = 0.994, P = 0.006), work of breathing (r = 0.995, P = 0.005), and transdiaphragmatic pressure (r = 0.998, P = 0.002).

Structured PICO

Does the NIRS-ICG technique provide a feasible index of respiratory muscle blood flow at different levels of ventilation in conscious humans?

Population

5 conscious humans

Intervention

Measurement of respiratory muscle blood flow using near-infrared spectroscopy (NIRS) and indocyanine green (ICG) dye during resting breathing and three 5-min bouts of constant isocapnic hyperpnea

Comparator

Inactive control muscle (vastus lateralis)

Outcome

Respiratory muscle blood flow (RMBF) at different levels of ventilationsurrogate

The NIRS-ICG technique provides a feasible and sensitive method to measure respiratory muscle blood flow in conscious humans during varying levels of ventilation.

Discussion

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Implication

NIRS-ICG appears feasible for respiratory muscle blood flow assessment in conscious humans; leaves open clinical validation and utility.

Cite This Study

Guenette et al. (2008) studied this question.

synapsesocial.com/papers/69d56fa375589c71d767da0a https://doi.org/10.1152/japplphysiol.01160.2007

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Human respiratory muscle blood flow measured by near-infrared spectroscopy and indocyanine green

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Human respiratory muscle blood flow measured by near-infrared spectroscopy and indocyanine green

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider