Interaction Between Body Temperature Changes and Hypoxemia to the Generation of Sighs in Adult Mice Anesthetized with Sevoflurane
Authors List
Mayumi Hashida, Takashi Nishino, Hisayo Jin, Saki Taiji, and Shiroh Isono
Department of Anesthesiology, Graduate School of Medicine, Chiba University, Japan
Background
Sighs are augmented breaths and occur spontaneously. A sigh is not only an
augmented breath but also prevents the collapse of alveoli and controls lung compliance. Hypoxia is known to increase the frequency of sighs, and sighs reset respiratory variability, controlling respiratory variability. Much evidence shows that the respiratory control system is sensitive to changes in body temperature. Assuming that the respiratory network responsible for the generation of sighs is sensitive to changes in body temperature, we hypothesized that changes in body temperature would greatly influence the generation of sighs.
Methods
Eleven adult spontaneously breathing mice anesthetized with 0.8 MAC sevoflurane were cooled from 36-37℃(normothermia) to 25-30℃ (mild hypothermia), then were warmed to 39-42℃(hyperthermia) while measuring changes in breathing patterns. During each temperature condition, they were exposed to two different O2 conditions, including room air (21% O2) and hypoxia (10% O2).
Results
During normothermia and hyperthermia, hypoxia increased the frequency of sighs. In contrast, sighs were scarcely observed during hypothermia with hypoxia, although a hypoxic response remained. In addition, under hyperthermia with hypoxia, tidal volume and respiratory frequency during eupnea gradually increased and changed into gasping. During gasping, sighs were never observed. However, with exposure to room air, sighs appeared again.
Conclusions
In spontaneously breathing mice anesthetized with sevoflurane, there appeared to be interactions between body temperature and hypoxemia to the generation of sighs. Gasping appeared to be a dominant breathing pattern over the sighs.
Mayumi Hashida, Takashi Nishino, Hisayo Jin, Saki Taiji, and Shiroh Isono
Department of Anesthesiology, Graduate School of Medicine, Chiba University, Japan
Background
Sighs are augmented breaths and occur spontaneously. A sigh is not only an
augmented breath but also prevents the collapse of alveoli and controls lung compliance. Hypoxia is known to increase the frequency of sighs, and sighs reset respiratory variability, controlling respiratory variability. Much evidence shows that the respiratory control system is sensitive to changes in body temperature. Assuming that the respiratory network responsible for the generation of sighs is sensitive to changes in body temperature, we hypothesized that changes in body temperature would greatly influence the generation of sighs.
Methods
Eleven adult spontaneously breathing mice anesthetized with 0.8 MAC sevoflurane were cooled from 36-37℃(normothermia) to 25-30℃ (mild hypothermia), then were warmed to 39-42℃(hyperthermia) while measuring changes in breathing patterns. During each temperature condition, they were exposed to two different O2 conditions, including room air (21% O2) and hypoxia (10% O2).
Results
During normothermia and hyperthermia, hypoxia increased the frequency of sighs. In contrast, sighs were scarcely observed during hypothermia with hypoxia, although a hypoxic response remained. In addition, under hyperthermia with hypoxia, tidal volume and respiratory frequency during eupnea gradually increased and changed into gasping. During gasping, sighs were never observed. However, with exposure to room air, sighs appeared again.
Conclusions
In spontaneously breathing mice anesthetized with sevoflurane, there appeared to be interactions between body temperature and hypoxemia to the generation of sighs. Gasping appeared to be a dominant breathing pattern over the sighs.
