Tidal breathing is also known as Chen-Schiff’s breathing. It is a periodic breathing abnormality. Characteristics: The respiration starts shallow and slow, then gradually accelerates and deepens, and after reaching the climax, it gradually becomes shallower and slower, and after a few seconds of respiratory pause (about 5-30 seconds), the above state of respiration appears again, and so on and so forth, and its respiratory movement is tide-like, so it is called tidal breathing. Mechanism of occurrence: When the excitability of the respiratory center is reduced, respiration is weakened to stop, resulting in hypoxia and carbon dioxide retention in the blood, which reflexively stimulates the respiratory center through the chemoreceptors of the carotid body and the aortic arch, causing respiration from weak to strong, and as respiration proceeds, carbon dioxide is expelled and the partial pressure of carbon dioxide is reduced, and respiration is again weakened to stop, thus forming periodic respiration. It is seen in patients with cerebral hemorrhage and increased intracranial pressure. Intermittent respiration is also known as Biot’s respiration. It is manifested by alternating respiration and apnea. Characteristics: After several regular breaths, breathing is suddenly suspended, with different cycle lengths, and then breathing starts again. This alternates repeatedly. Mechanism of occurrence: Same as tidal breathing, as a manifestation of significantly reduced excitability of the respiratory center, but more severe than tidal breathing, mostly appearing before respiratory arrest. It is seen in patients with intracranial lesions and respiratory center failure.