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段 雪, 韦 锦, 梁 安, 纪 雪. [Small tidal volume hyperventilation relieves intraocular and intracranial pressure elevation in prone spinal surgery: a randomized controlled trial]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2024; 44:660-665. [PMID: 38708498 PMCID: PMC11073951 DOI: 10.12122/j.issn.1673-4254.2024.04.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Indexed: 05/07/2024]
Abstract
OBJECTIVE To investigate the effects of different ventilation strategies on intraocular pressure (IOP) and intracranial pressure in patients undergoing spinal surgery in the prone position under general anesthesia. METHODS Seventy-two patients undergoing prone spinal surgery under general anesthesia between November, 2022 and June, 2023 were equally randomized into two groups to receive routine ventilation (with Vt of 8mL/kg, Fr of 12-15/min, and etCO2 maintained at 35-40 mmHg) or small tidal volume hyperventilation (Vt of 6 mL/kg, Fr of18-20/min, and etCO2 maintained at 30-35 mmHg) during the surgery. IOP of both eyes (measured with a handheld tonometer), optic nerve sheath diameter (ONSD; measured at 3 mm behind the eyeball with bedside real-time ultrasound), circulatory and respiratory parameters of the patients were recorded before anesthesia (T0), immediately after anesthesia induction (T1), immediately after prone positioning (T2), at 2 h during operation (T3), immediately after supine positioning after surgery (T4) and 30 min after the operation (T5). RESULTS Compared with those at T1, IOP and ONSD in both groups increased significantly at T3 and T4(P < 0.05). IOP was significantly lower in hyperventilation group than in routine ventilation group at T3 and T4(P < 0.05), and ONSD was significantly lower in hyperventilation group at T4(P < 0.05). IOP was positively correlated with the length of operative time (r=0.779, P < 0.001) and inversely with intraoperative etCO2 at T3(r=-0.248, P < 0.001) and T4(r=-0.251, P < 0.001).ONSD was correlated only with operation time (r=0.561, P < 0.05) and not with IOP (r=0.178, P>0.05 at T3; r=0.165, P>0.05 at T4). CONCLUSION Small tidal volume hyperventilation can relieve the increase of IOP and ONSD during prone spinal surgery under general anesthesia.
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Affiliation(s)
- 雪飞 段
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 锦锋 韦
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 安怡 梁
- 南方医科大学附属广东省人民医院眼科, 广东 广州 510080Department of Ophthalmology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
| | - 雪霞 纪
- 南方医科大学附属广东省人民医院麻醉科, 广东 广州 510080Department of Anesthesiology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou 510080, China
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Ustick JJ, Pardon LP, Chettry P, Patel NB, Cheng H. Effects of head-down tilt on optic nerve sheath diameter in healthy subjects. Ophthalmic Physiol Opt 2023; 43:1531-1539. [PMID: 37401194 PMCID: PMC10592427 DOI: 10.1111/opo.13200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/05/2023]
Abstract
PURPOSE Intracranial pressure increases in head-down tilt (HDT) body posture. This study evaluated the effect of HDT on the optic nerve sheath diameter (ONSD) in normal subjects. METHODS Twenty six healthy adults (age 28 [4.7] years) participated in seated and 6° HDT visits. For each visit, subjects presented at 11:00 h for baseline seated scans and then maintained a seated or 6° HDT posture from 12:00 to 15:00 h. Three horizontal axial and three vertical axial scans were obtained at 11:00, 12:00 and 15:00 h with a 10 MHz ultrasonography probe on the same eye, randomly chosen per subject. At each time point, horizontal and vertical ONSD (mm) were quantified by averaging three measures taken 3 mm behind the globe. RESULTS In the seated visit, ONSDs were similar across time (p > 0.05), with an overall mean (standard deviation) of 4.71 (0.48) horizontally and 5.08 (0.44) vertically. ONSD was larger vertically than horizontally at each time point (p < 0.001). In the HDT visit, ONSD was significantly enlarged from baseline at 12:00 and 15:00 h (p < 0.001 horizontal and p < 0.05 vertical). Mean (standard error) horizontal ONSD change from baseline was 0.37 (0.07) HDT versus 0.10 (0.05) seated at 12:00 h (p = 0.002) and 0.41 (0.09) HDT versus 0.12 (0.06) seated at 15:00 h (p = 0.002); mean vertical ONSD change was 0.14 (0.07) HDT versus -0.07 (0.04) seated at 12:00 h (p = 0.02) and 0.19 (0.06) HDT versus -0.03 (0.04) seated at 15:00 h (p = 0.01). ONSD change in HDT was similar between 12:00 and 15:00 h (p ≥ 0.30). Changes at 12:00 h correlated with those at 15:00 h for horizontal (r = 0.78, p < 0.001) and vertical ONSD (r = 0.73, p < 0.001). CONCLUSION The ONSD increased when body posture transitioned from seated to HDT position without any further change at the end of the 3 h in HDT.
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Affiliation(s)
| | - Laura P. Pardon
- University of Houston, College of Optometry, Houston, Texas, USA
| | - Pratik Chettry
- University of Houston, College of Optometry, Houston, Texas, USA
| | - Nimesh B. Patel
- University of Houston, College of Optometry, Houston, Texas, USA
| | - Han Cheng
- University of Houston, College of Optometry, Houston, Texas, USA
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Pardon LP, Greenwald SH, Ferguson CR, Patel NB, Young M, Laurie SS, Macias BR. Identification of Factors Associated With the Development of Optic Disc Edema During Spaceflight. JAMA Ophthalmol 2022; 140:1193-1200. [PMID: 36301519 PMCID: PMC9614681 DOI: 10.1001/jamaophthalmol.2022.4396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/01/2022] [Indexed: 01/12/2023]
Abstract
Importance Approximately 70% of crew members who complete long-duration missions to the International Space Station develop signs of optic disc edema, a hallmark finding of spaceflight-associated neuro-ocular syndrome. The onset and magnitude of edema differ across individuals, and the reason for this variability remains unknown. Identifying risk factors for spaceflight-induced disc edema is important because this condition may become more severe during extended-duration missions to the moon and Mars and could be associated with irreversible vision loss. Objective To assess whether preflight indicators of crowded optic nerve head morphology, other ocular measures (such as choroid thickness and axial length), body weight, body mass index, sex, age, and previous flight experience are associated with optic disc edema development. Design, Setting, and Participants This cohort study analyzed ocular, body weight, and demographic data collected from 31 US and international crew members before, during, and after spaceflight at the NASA Johnson Space Center and International Space Station. Ocular factors assessed included preflight and in-flight peripapillary total retinal thickness, minimum rim width, optic cup volume, mean cup depth, mean cup width, cup-disc ratio, Bruch membrane opening area, retinal nerve fiber layer thickness, choroid thickness, axial length, and refractive error. In addition, body weight, body mass index, sex, age, and previous spaceflight experience were assessed for associations with optic disc edema development. The data were analyzed from August 2021 to June 2022. Exposure Approximately 6 to 12 months of spaceflight. Main Outcomes and Measures In-flight increases in peripapillary total retinal thickness. Linear mixed models were used to assess for associations between a wide range of risk factors and in-flight increases in peripapillary total retinal thickness, which is a sensitive objective measure for detecting optic disc edema. Results This study included 31 International Space Station crew members with a mean (SD) age of 46.9 (6.0) years (25 men [80.6%]). During spaceflight, mean (SE) peripapillary total retinal thickness increased from 392.0 (5.8) μm to 430.2 (9.6) μm (P < .001), and greater individual changes were associated with smaller preflight cup volume (slope [SE], -62.8 [18.9]; P = .002), shallower preflight cup depth (slope [SE], -0.11 [0.03]; P < .001), and narrower preflight cup width (slope [SE], -0.03 [0.01]; P = .03). No associations were observed between changes in peripapillary total retinal thickness and any other variable evaluated. Conclusions and Relevance Findings of this cohort study suggest that smaller optic cup morphology may be associated with optic disc edema development during spaceflight. Crew members with this cup profile may benefit from enhanced ophthalmic monitoring during spaceflight and use of countermeasures against spaceflight-associated neuro-ocular syndrome.
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Affiliation(s)
| | | | | | | | - Millennia Young
- National Aeronautics and Space Administration Johnson Space Center, Houston, Texas
| | | | - Brandon R. Macias
- National Aeronautics and Space Administration Johnson Space Center, Houston, Texas
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Pardon LP, Macias BR, Ferguson CR, Greenwald SH, Ploutz-Snyder R, Alferova IV, Ebert D, Dulchavsky SA, Hargens AR, Stenger MB, Laurie SS. Changes in Optic Nerve Head and Retinal Morphology During Spaceflight and Acute Fluid Shift Reversal. JAMA Ophthalmol 2022; 140:763-770. [PMID: 35708665 DOI: 10.1001/jamaophthalmol.2022.1946] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Importance Countermeasures that reverse the headward fluid shift experienced in weightlessness have the potential to mitigate spaceflight-associated neuro-ocular syndrome. This study investigated whether use of the countermeasure lower-body negative pressure during spaceflight was associated with changes in ocular structure. Objective To determine whether changes to the optic nerve head and retina during spaceflight can be mitigated by brief in-flight application of 25-mm Hg lower-body negative pressure. Design, Setting, and Participants In the National Aeronautics and Space Administration's "Fluid Shifts Study," a prospective cohort study, optical coherence tomography scans of the optic nerve head and macula were obtained from US and international crew members before flight, in-flight, and up to 180 days after return to Earth. In-flight scans were obtained both under normal weightless conditions and 10 to 20 minutes into lower-body negative pressure exposure. Preflight and postflight data were collected in the seated, supine, and head-down tilt postures. Crew members completed 6- to 12-month missions that took place on the International Space Station. Data were analyzed from 2016 to 2021. Interventions or Exposures Spaceflight and lower-body negative pressure. Main Outcomes and Measures Changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thickness, and macular thickness. Results Mean (SD) flight duration for the 14 crew members (mean [SD] age, 45 [6] years; 11 male crew members [79%]) was 214 (72) days. Ocular changes on flight day 150, as compared with preflight seated, included an increase in minimum rim width (33.8 μm; 95% CI, 27.9-39.7 μm; P < .001), decrease in cup volume (0.038 mm3; 95% CI, 0.030-0.046 mm3; P < .001), posterior displacement of Bruch membrane opening (-9.0 μm; 95% CI, -15.7 to -2.2 μm; P = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; P < .001). Brief exposure to lower-body negative pressure did not affect these parameters. Conclusions and Relevance Results of this cohort study suggest that peripapillary tissue thickening, decreased cup volume, and mild central macular thinning were associated with long-duration spaceflight. Acute exposure to 25-mm Hg lower-body negative pressure did not alter optic nerve head or retinal morphology, suggesting that longer durations of a fluid shift reversal may be needed to mitigate spaceflight-induced changes and/or other factors are involved.
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Affiliation(s)
| | - Brandon R Macias
- National Aeronautics and Space Administration Johnson Space Center, Houston, Texas
| | | | | | | | - Irina V Alferova
- Russian Federation State Research Center Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | | | | | - Alan R Hargens
- Department of Orthopedic Surgery, UC San Diego Medical Center, University of California, San Diego
| | - Michael B Stenger
- National Aeronautics and Space Administration Johnson Space Center, Houston, Texas
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Vitiello L, De Bernardo M, Capasso L, Cornetta P, Rosa N. Optic Nerve Ultrasound Evaluation in Animals and Normal Subjects. Front Med (Lausanne) 2022; 8:797018. [PMID: 35071277 PMCID: PMC8766506 DOI: 10.3389/fmed.2021.797018] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/13/2021] [Indexed: 12/15/2022] Open
Abstract
In recent years, ultrasonographic measurement of the optic nerve sheath diameter (ONSD) has been widely used to identify the presence of increased intracranial pressure (ICP). Intracranial hypertension is a life-threatening condition that can be caused by various neurological and non-neurological disorders, and it is associated to poor clinical results. Ultrasonography could be used to qualitatively and efficiently detect ICP increases, but to reach this purpose, clear cut-off values are mandatory. The aim of this review is to provide a wide overview of the most important scientific publications on optic nerve ultrasound normal values assessment published in the last 30 years. A total of 42 articles selected from PubMed medical database was included in this review. Our analysis showed that ocular ultrasonography is considered to be a valuable diagnostic tool, especially when intracranial hypertension is suspected, but unfortunately this research provided conflicting results that could be due to the different ultrasound protocols. This is mainly caused by the use of B scan alone, which presents several limitations. The use of B-scan coupled with the standardized A-scan approach could give more accurate, and reliable ultrasound evaluation, assuring higher data objectivity.
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Affiliation(s)
- Livio Vitiello
- Eye Unit, Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana", University of Salerno, Baronissi, Italy
| | - Maddalena De Bernardo
- Eye Unit, Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana", University of Salerno, Baronissi, Italy
| | - Luigi Capasso
- Corneal Transplant Unit, Azienda Sanitaria Locale (ASL) Napoli 1, Naples, Italy
| | - Palmiro Cornetta
- Eye Unit, "Maria SS Addolorata" Hospital, Azienda Sanitaria Locale (ASL) Salerno, Eboli, Italy
| | - Nicola Rosa
- Eye Unit, Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana", University of Salerno, Baronissi, Italy
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Stability of OCT and OCTA in the Intensive Therapy Unit Setting. Diagnostics (Basel) 2021; 11:diagnostics11081516. [PMID: 34441449 PMCID: PMC8394026 DOI: 10.3390/diagnostics11081516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/03/2021] [Accepted: 08/13/2021] [Indexed: 11/23/2022] Open
Abstract
To assess the stability of retinal structure and blood flow measures over time and in different clinical settings using portable optical coherence tomography angiography (OCTA) as a potential biomarker of central perfusion in critical illness, 18 oesophagectomy patients completed retinal structure and blood flow measurements by portable OCT and OCTA in the eye clinic and intensive therapy unit (ITU) across three timepoints: (1) pre-operation in a clinic setting; (2) 24–48 h post-operation during ITU admission; and (3) seven days post-operation, if the patient was still admitted. Blood flow and macular structural measures were stable between the examination settings, with no consistent variation between pre- and post-operation scans, while retinal nerve fibre layer thickness increased in the post-operative scans (+2.31 µm, p = 0.001). Foveal avascular zone (FAZ) measurements were the most stable, with an intraclass correlation coefficient of up to 0.92 for right eye FAZ area. Blood flow and structural measures were lower in left eyes than right eyes. Retinal blood flow assessed in patients before and during an ITU stay using portable OCTA showed no systematic differences between the clinical settings. The stability of retinal blood flow measures suggests the potential for portable OCTA to provide clinically useful measures in ITU patients.
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Ong J, Lee AG, Moss HE. Head-Down Tilt Bed Rest Studies as a Terrestrial Analog for Spaceflight Associated Neuro-Ocular Syndrome. Front Neurol 2021; 12:648958. [PMID: 33841315 PMCID: PMC8032981 DOI: 10.3389/fneur.2021.648958] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 03/01/2021] [Indexed: 01/16/2023] Open
Abstract
Astronauts who undergo prolonged periods of spaceflight may develop a unique constellation of neuro-ocular findings termed Spaceflight Associated Neuro-Ocular Syndrome (SANS). SANS is a disorder that is unique to spaceflight and has no terrestrial equivalent. The prevalence of SANS increases with increasing spaceflight duration and although there have been residual, structural, ocular changes noted, no irreversible or permanent visual loss has occurred after SANS, with the longest spaceflight to date being 14 months. These microgravity-induced findings are being actively investigated by the United States' National Aeronautics Space Administration (NASA) and SANS is a potential obstacle to future longer duration, manned, deep space flight missions. The pathophysiology of SANS remains incompletely understood but continues to be a subject of intense study by NASA and others. The study of SANS is of course partially limited by the small sample size of humans undergoing spaceflight. Therefore, identifying a terrestrial experimental model of SANS is imperative to facilitate its study and for testing of preventative measures and treatments. Head-down tilt bed rest (HDTBR) on Earth has emerged as one promising possibility. In this paper, we review the HDTBR as an analog for SANS pathogenesis; the clinical and imaging overlap between SANS and HDTBR studies; and potential SANS countermeasures that have been or could be tested with HDTBR.
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Affiliation(s)
- Joshua Ong
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Andrew G Lee
- Department of Ophthalmology, Houston Methodist Hospital, Houston, TX, United States.,Baylor College of Medicine and the Center for Space Medicine, Houston, TX, United States.,The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, United States.,Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, United States.,Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, United States.,University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Texas A and M College of Medicine, Bryan, TX, United States.,Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, United States
| | - Heather E Moss
- Departments of Ophthalmology, Stanford University, Palo Alto, CA, United States.,Departments of Neurology & Neurosciences, Stanford University, Palo Alto, CA, United States
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