What is pen blocking in polysomnography?

Pen blocking in polysomnography refers to an issue that occurs when the tracing stylus of the polysomnography (PSG) machine reaches the uppermost or lowermost limits of the recording channels, resulting in a blockage where the stylus cannot move past these boundaries. This behavior is significant because it can lead to the loss of important data during sleep studies, preventing accurate interpretation of physiological signals such as brain waves, muscle activity, and heart rhythm. When the threshold is reached, the graph might flatline at the maximum or minimum point, which can obscure the clinical picture and lead to misinterpretation of the patient’s sleep patterns or disturbances. Understanding pen blocking is important for ensuring the quality of sleep studies and providing effective patient care.