Khurana A, Thach B T
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Appl Physiol (1985). 1996 Feb;80(2):472-7. doi: 10.1152/jappl.1996.80.2.472.
Severe hypoxia produces a state of neural depression known as hypoxic coma in which reflex activity is believed to be absent but from which spontaneous recovery ("autoresuscitation") still can occur. We evaluated the swallowing reflex during hypoxic coma by employing mechanical and chemosensory stimuli. BALB/c mice were given 97% N2-3% CO2 to breathe. At onset of coma, a 0.05-ml bolus of saline or water was infused into the pharynx. Unlike mechanical stimulation (sham infusion), fluid infusion usually was followed by rapid swallowing, more so with water than with saline. This model allowed examination of interactions among swallowing, hypoxic gasping, airway fluid removal, and autoresuscitation. Compared with sham infusion, saline and water reduced gasping rate equally. Saline, however, prolonged the process of autoresuscitation more than did water, an effect possibly related to an observed increased retention of saline in the airway. Occasionally, mice failed to swallow after infusions, in which case airway obstruction during gasping and autoresuscitation failure was repeatedly observed. These studies suggest that the swallowing component of the laryngeal chemoreflex is present during hypoxic coma and that swallowing facilitates autoresuscitation when upper airway fluid is present.
严重缺氧会产生一种称为缺氧昏迷的神经抑制状态，在这种状态下，反射活动被认为不存在，但仍可能发生自发恢复（“自动复苏”）。我们通过采用机械和化学感觉刺激来评估缺氧昏迷期间的吞咽反射。给BALB/c小鼠吸入97% N₂ - 3% CO₂。在昏迷开始时，将0.05毫升的生理盐水或水注入咽部。与机械刺激（假注入）不同，液体注入后通常会迅速吞咽，水引起的吞咽比生理盐水更明显。该模型允许研究吞咽、缺氧喘息、气道液体清除和自动复苏之间的相互作用。与假注入相比，生理盐水和水同样降低了喘息率。然而，生理盐水比水更能延长自动复苏过程，这种效应可能与观察到的气道中生理盐水潴留增加有关。偶尔，小鼠在注入后未能吞咽，在这种情况下，反复观察到喘息期间的气道阻塞和自动复苏失败。这些研究表明，喉化学反射的吞咽成分在缺氧昏迷期间存在，并且当存在上呼吸道液体时，吞咽有助于自动复苏。
