From the Guidelines
Rapid Eye Movement Sleep Behavior Disorder (RBD) is a parasomnia characterized by abnormal or disruptive behaviors emerging during rapid eye movement (R) sleep, having the potential to cause injury or sleep disruption, and is typically diagnosed using polysomnography (PSG) showing loss of normal electromyographic (EMG) atonia. RBD is usually presented after the age of 50, though any age group can be affected, with a predilection for male gender, and prevalence estimates are 0.38% to 0.5% in the general population 1. The disorder can be idiopathic or secondary, related to neurodegenerative disorders, other neurologic disorders, sleep disorders, or medications, including withdrawal states, and appears to be associated with the α-synucleinopathies, such as Parkinson disease (PD), dementia of Lewy body (DLB) type, and multiple system atrophy (MSA) 1. Some key features of RBD include:
- Abnormal behaviors during R sleep, such as talking, laughing, shouting, gesturing, grabbing, flailing arms, punching, kicking, and sitting up or leaping from bed
- Loss of normal EMG atonia, manifest as either or both sustained muscle activity during R sleep in the chin EMG and excessive transient muscle activity (phasic muscle twitches) in either the chin or limb EMG
- Risk of sleep-related injury (SRI), with between 33% and 65% of RBD patients reported to have had sleep-related injury to self or bed partner 1. The diagnosis and management of RBD should prioritize the prevention of sleep-related injuries and the treatment of underlying associated conditions, such as α-synucleinopathies, and should be guided by the most recent and highest quality evidence, such as the 2010 best practice guide for the treatment of RBD 1.
From the Research
Definition and Explanation of RER
- The Respiratory Exchange Ratio (RER) is a measure of the ratio of total carbon dioxide produced over total oxygen consumed by an organism 2.
- It serves as a qualitative measure to determine the substrate usage of a particular organism on the whole body level 2.
- RER can be used to estimate the percentage of glucose and lipid oxidation at a given timepoint 2.
Factors Influencing RER
- Muscle glycogen content, training volume, proportion of type 1 fibers, free fatty acid and lactate levels, and dietary fat intake are major determinants of resting RER 3.
- During exercise, the key determinants of RER vary with intensity, including blood-borne substrate, muscle substrate, glycolytic enzyme activities, and lactate levels 3.
- Resting RER is also a significant determinant of RER at low to moderate exercise intensities 3.
Measurement and Interpretation of RER
- RER can be measured using indirect calorimetry, which provides a non-invasive estimate of substrate utilization 2.
- Nonprotein respiratory quotient tables can be used to convert RER values into estimates of glucose and lipid oxidation, but these tables have limitations 2.
- A new mathematical model has been developed to provide a more accurate and straightforward approach to converting continuous RER values into estimates of glucose and lipid oxidation 2.