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Yao Y, Chen J, Li X, Chen ZF, Li P. A carotid body-brainstem neural circuit mediates sighing in hypoxia. Curr Biol 2023; 33:827-837.e4. [PMID: 36750092 DOI: 10.1016/j.cub.2023.01.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 11/09/2022] [Accepted: 01/10/2023] [Indexed: 02/08/2023]
Abstract
Increased ventilation is a critical process that occurs when the body responds to a hypoxic environment. Sighs are long, deep breaths that prevent alveolar collapse, and their frequency is significantly increased by hypoxia. In this study, we first show that sighing is induced by hypoxia as a function of increased hypoxic severity and that hypoxia-induced sighing is capable of increasing the oxygen saturation in a mouse model. We next found that the gastrin-releasing peptide (Grp) expressing neurons in the nucleus of the solitary tract (NTS) are important in mediating hypoxia-induced sighing. Retrograde tracing from these Grp neurons reveals their direct afferent input from the petrosal ganglion neurons that innervate the carotid body, the major peripheral chemoreceptor that senses blood oxygen. Acute hypoxia preferentially activates these Grp neurons in the NTS. Photoactivation of these neurons through their projections in the inspiratory rhythm generator in the ventral medulla induces sighing, whereas genetic ablation or chemogenetic silencing of these neurons specifically diminishes the sighs, but not other respiratory responses, induced by hypoxia. Finally, the mice with reduced sighing in hypoxia exhibit an elevated heart-rate increase, which may compensate for maintaining the blood oxygen level. Therefore, we identified a neural circuit that connects the carotid body to the breathing control center in the ventral medulla with a specific function for hypoxia-induced sighing, which restores the oxygen level.
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Affiliation(s)
- Yilong Yao
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Jingwen Chen
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xingyu Li
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhou-Feng Chen
- Department of Anesthesiology, Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Peng Li
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular and Integrative Physiology, School of Medicine, University of Michigan, Ann Arbor, MI 48109, USA.
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Kim SY, Lee HJ, Lee JK, Park TY, Heo EY, Kim DK, Chung HS, Lee HW. Association between oxygen saturation level during bronchoscopy and post-bronchoscopy adverse events: a retrospective cohort study. Respir Res 2022; 23:144. [PMID: 35655299 PMCID: PMC9161191 DOI: 10.1186/s12931-022-02063-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 05/23/2022] [Indexed: 11/11/2022] Open
Abstract
Background Flexible bronchoscopy is widely used to diagnose and treat various respiratory diseases. However, caution is warranted for post-bronchoscopy adverse events. Although desaturation frequently occurs during bronchoscopy, its clinical impact and the optimal oxygen saturation level during the procedure remain unclear. This study aimed to investigate whether the percutaneous oxygen saturation (SpO2) level during bronchoscopy is associated with the development of post-bronchoscopy respiratory adverse events. Methods In this single-center retrospective cohort study conducted from March 2020 to February 2021, 569 patients were classified into high or low oxygen saturation groups based on the SpO2 level during bronchoscopy. The primary outcome was post-bronchoscopy respiratory adverse events, and secondary outcomes were other post-bronchoscopy adverse events and clinical outcomes. Results Among 569 patients, 458 and 111 patients were classified into the high oxygen saturation (SpO2 > 96%) and low oxygen saturation (SpO2 ≤ 94%) groups, respectively. After propensity score matching, the low oxygen saturation group had more post-bronchoscopy respiratory and febrile adverse events than the high oxygen saturation group. In the multivariable regression analysis, low SpO2 level during bronchoscopy was an independent risk factor for post-bronchoscopy respiratory adverse events (odds ratio = 3.16 [95% confidence interval 1.37–7.30]). In the low oxygen saturation group, the high-risk subgroups for post-bronchoscopy respiratory adverse events were the elderly, women, current smokers, and patients with chronic obstructive pulmonary disease or acute decompensated heart failure before bronchoscopy. There was no significant difference in the length of hospital stay, intensive care unit admission, or mortality between the high and low oxygen saturation groups. Conclusions Close monitoring is recommended for patients with SpO2 ≤ 94% during bronchoscopy due to the increased risk of respiratory adverse events after the procedure. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-022-02063-0.
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Affiliation(s)
- So Yeon Kim
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Hyo Jin Lee
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Jung Kyu Lee
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Tae Yeon Park
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Eun Young Heo
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Deog Kyeom Kim
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Hee Soon Chung
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea
| | - Hyun Woo Lee
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea.
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Blevins CE, Celeste NA, Marx JO. Effects of Oxygen Supplementation on Injectable and Inhalant Anesthesia in C57BL/6 Mice. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2021; 60:289-297. [PMID: 33972009 DOI: 10.30802/aalas-jaalas-20-000143] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Oxygen supplementation is rarely considered when anesthetizing laboratory mice, despite reports that mice become profoundly hypoxic under anesthesia. Little is known about the effects of hypoxia on anesthetic performance. This article focuses on the effects of oxygen supplementation on physiologic parameters and depth of anesthesia in male and female C57BL/6 mice. Anesthesia was performed via common injectable anesthetic protocols and with isoflurane. Mice anesthetized with injectable anesthesia received one of 3 drug protocols. Low-dose ketamine/xylazine (100/8 mg/kg) was chosen to provide immobilization of mice, suitable for imaging procedures. Medium-dose ketamine/xylazine/acepromazine (100/10/1 mg/kg) was chosen as a dose that has been recommended for surgical procedures. High-dose ketamine/xylazine/acepromazine (150/12/3 mg/kg) was chosen after pilot studies to provide a long duration of a deep plane of anesthesia. We also tested the effects of oxygen supplementation on the minimum alveolar concentration (MAC) of isoflurane in mice. Mice breathed supplemental 100% oxygen, room air, or medical air with 21% oxygen. Anesthetized mice that did not receive supplemental oxygen all became hypoxic, while hypoxia was prevented in mice that received oxygen. Oxygen supplementation did not affect the MAC of isoflurane. At the high injectable dose, all mice not receiving oxygen supplementation died while all mice receiving oxygen supplementation survived. At low and medium doses, supplemental oxygen reduced the duration of the surgical plane of anesthesia (low dose with oxygen: 22 ± 14 min; low dose without supplementation: 29 ± 18 min; medium dose with oxygen: 43 ± 18 min; medium dose without supplementation: 61 ± 27 min). These results suggest that mice anesthetized with injectable and inhalant anesthesia without supplemental oxygen are routinely hypoxic. This hypoxia prolongs the duration of anesthesia with injectable drug protocols and affects survival at high doses of injectable anesthetics. Because of variable responses to injectable anesthetics in mice, oxygen supplementation is recommended for all anesthetized mice.
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Affiliation(s)
- Caroline E Blevins
- University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania; University of Pennsylvania School of Veterinary Medicine, Philadelphia, Dept. of Pathobiology, Philadelphia, Pennsylvania
| | - Natalie A Celeste
- The Ohio State University College of Veterinary Medicine, Columbus, Ohio
| | - James O Marx
- University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania; University of Pennsylvania School of Veterinary Medicine, Philadelphia, Dept. of Pathobiology, Philadelphia, Pennsylvania;,
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