Space Physiology Human Health and Performance Academy Lecture - PowerPoint PPT Presentation

https://ntrs.nasa.gov/search.jsp?R=20130008754 2018-01-25T22:02:24+00:00Z Space Physiology Human Health and Performance Academy Lecture Visual Impairment and Intracranial Pressure (VIIP): What is it and what does it tell us about Spaceflight Physiology? Jennifer Fogarty, PhD Clinical Translational Scientist Space and Clinical Operations Division Human Health and Performance Directorate January 17, 2013

Contributors • Christian Otto • LSAH - epidemiology • Dave Francisco • BDRA – increment roll up • JD Polk • HRP HHC Element • Ashot Sargsyan • VIIP RCAP • Doug Hamilton • VIIP IWG 2

Agenda • Duration of Spaceflight • Visual Impairment and • Historical Context Intracranial Pressure • Spaceflight Physiology – Incidence • Data Collected – Vascular, Central Nervous, • Countermeasures Ocular components – Cardiovascular Physiology • Transition to Operations Refresher – Fluid shift – Imaging of the Eye and Evidence – Theory - ICP – Clinical Practice Guideline 3

Human Spaceflight Experience: The Long and the Short of it… Characteristics of the Vehicle Habitat Environment Partial Gravity Exposure Countermeasure Availability Physiological, Medical, Environmental Data

Historical Perspective • Gemini 5 (8 day mission) • Apollo – Visual Tester in-flight – Retinal vascular photography reveals – Visual acuity retinal vessels measurement program “decreased in size” at 3.5 – Large rectangles at hours into flight. ground sites in Texas and – 100% oxygen Australia. atmosphere – No changes noted in – No visual acuity changes astronaut visual acuity postflight. – Hawkins and Zieglschmid, 1975 – Duntley et al, 1966 5

Shuttle • 10-14 day missions • 122 crewmembers between 1995 and • Anecdotal reports of 1998, 15% indicated vision changes, but decrements in near return to baseline. vision on orbit. Returns • 1 astronaut with to baseline. bilateral lens implants • Paloski et al 2008 • No optic disc edema cases, but an occasional choroidal fold. 6

Differences Between Historical and Present • Missions were 5 to 17 days • Missions average 6 months generally (Skylab a notable on ISS exception) • Astronaut mean age 46.7 • Astronaut age was mean of • MRI, OCT, Telemedicine 38 fundoscopy • MRI and OCT not available • 14.7 psi, 21% oxygen • Spacecraft ranged from 5.0 • Robust exercise suite psi to 10.7 psi to 14.7 psi with varying oxygen concentrations 7

Human Response to Spaceflight Astronauts experience a spectrum of adaptations in •Neurovestibular flight and post flight Exposures: •Cardiovascular Launch & Landing Loads •Skeletal Microgravity Closed Environment (air and water) •Muscular Confined Habitat Radiation Exposure •Immunological •Nutritional Balance disorders Cardiovascular deconditioning Decreased immune function •Behavioral Muscle atrophy Bone loss

Time Course of Physiological Changes During Weightlessness

Physiological & Psychosocial Manifestations Associated with Space Flight Cardiovascular Bone  Fluid volume  Bone mineral content  Orthostatic tolerance  Bone mineral density  Aerobic capacity  Urinary calcium  Arrhythmias  Renal stone risk Psychosocial Skeletal Muscle  Team issues  Skeletal muscle mass  Confinement issues  Skeletal muscle strength  Fatigue  Skeletal muscle endurance  Stress   Skeletal muscle capillary Errors density  Cognitive Function Neurosensory Environmental   Vestibular disturbances CO2 (2-5 mmHg)*   Hearing loss due to Space motion sickness acoustics  Sensorimotor function  Radiation exposure  Postural & locomotor  Risk of cataracts/cancers stability  Skin irritations due to GI/Pharmacokinetics microbial growths  GI motility and PK

Biomedical Data • Data Collected via Medical Requirements • Assessments of: – Bone – Cardiovascular – Aerobic Fitness – Sensory Motor – Functional Fitness – Nutritional Status

International Space Station Medical Requirements collect physiological, medical and environmental data Pelvis BMD % Change from Preflight Expeditions 1-16 (n=20) Loss 0 =7.7% Recovery Half-life=97 d 5.0 10 10 0.0 5 5 0 0 -5.0 BMD Change (%) BMD Change (%) -5 -5 -10.0 -10 -10 -15.0 -15 -15 -20.0 -20 -20 -25.0 -25 -25 -30.0 0 0 300 300 600 600 900 900 1200 1200 1500 1500 Lumbar Femoral Trochanter Whole Heel Pelvis Days-After-Landing Days-After-Landing Spine Neck Body Percent Change in Estimated VO2 Index from Pre-Flight Expeditions 1-16 (n=20) 50 40 30 % change from pre-flight 20 10 0 -10 -20 -30 -40 0-29 30-69 70-99 100-129 130-149 150+ R+4-7 R+30-35 Data can be used to assess the individual or the population 12 12

Bone compartments or bone types Cancellous “Spongy” Bone/Trabecular Bone PROXIMAL FEMUR VERTEBRAL BODY Trochanter Femoral Neck Cortical Bone/ “Compact Bone” An example of a spaceflight adaptation that is well described but still lacks understanding of time course, recovery, and long term risk Sources: L. Mosekilde; SL Bonnick; P Crompton

ISS Exercise Hardware Availability Timeline EXP9 EXP10 EXP11 EXP12 EXP13 EXP14 EXP15 EXP16 EXP6 EXP7 EXP8 EXP1 EXP2 EXP3 EXP4 EXP5 CEVIS CEVIS Assembly restricted to failing control CCC failed control DC power arm ergometry panel Installed panel; CCC converter installed failure I-RED Assembly I-RED Incorrect thimble SchRED on new cord replaces I- RED TVIS Assembly TVIS 7th fwd stbd roller deteriorated 10/00 03/01 08/01 12/01 06/02 11/02 04/03 10/03 04/04 10/04 04/05 09/05 03/06 09/06 04/07 10/07 = Restricted use = Nominal availability = No availability

Countermeasures Research Operational

A consequence of human spaceflight • Visual Impairment and Intracranial Pressure (VIIP) What is the problem? • Optic Disc Edema, Globe Flattening, Choroidal Folds, Hyperopic Shifts and Raised Intracranial – Pressure has occurred in Astronauts During and After Long Duration Space Flight • What is the risk? – Given that all astronauts experience a microgravity-induced cephalad fluid shift and that both symptomatic and asymptomatic individuals have exhibited optic nerve sheath edema on MRI, there is a high probability that all astronauts have some degree of idiopathic intracranial hypertension. Those that are susceptible (due to eye architecture, anatomy, narrow disc, etc.) have a high likelihood of developing either choroidal folds or papilledema, and the degree of edema will determine impairment and long-term or permanent vision loss.

A consequence of human spaceflight • Visual Impairment and Intracranial Pressure (VIIP) – Operational processes (medical requirement) put in place to diagnose and manage 2008 (fundoscope and eye ultrasound) – Sentinel case found retrospectively (2005; Exp 11) – Integrated approach kicked off to address the issue: 2010 – Research and Clinical Advisory Panel formulated in 2011 – Occupational Health Research Protocol developed 2012 – 9 Studies funded in 2012

Vision Impairment & Intracranial Pressure Risk Update Incidence Rate Incidence rate of VIIP per the CPG classifications 36 long duration US astronauts 21 Evaluated as of 7/2012 Refractive changes ≥ .50 diopter cycloplegic 20 refractive change and/or cotton wool spot + Choroidal folds and/or ONSD and/or Number of Cases 42% 15 globe flattening and/or scotoma + Optic Disc Edema 0-2 10 38% Optic Disc Edema 3-4 29% 19% 5 10% 5% N=15 N=6 N=2 N=8 N=1 N=4 0 Not Evaluated Class 0 Class 1 Class 2 Class 3 Class 4 CPG Classification 21 crew members have been evaluated These crewmembers did not have MRIs, OCTs or cycloplegic refraction – NASA is in the process of 15 have symptoms – 15/21 = 71% obtaining this information/evaluation Class 3 and 4 – 5/21 = 24% 18

VIIP: A Three-Part Story 1. The Vascular System 2. The Brain 3. The Eye + + Demographic MRI Intracranial (Pre/Post) Intraocular pressure Gender Peak CSF flow Corneal Thickness Age CSF Production Visual acuity (Pre/In/Post) Race Glove Flattening Refractive error (Pre/Post) Body Composition Globe Axial Length Optic Disc:Cup ratio (Pre/Post) Height Optic Nerve Tortuosity OCT (Pre/Post) Weight Ultrasound (Pre/In/Post) RNFL % Lean Body Mass ONSD RPE angle %Fat Body Mass Nerve/Sheath Ratio Optic nerve head Cardiac Environmental Choroidal Folds Resting Blood pressure CO2 Levels High Res Retinal Photography Resting Cardiac output Retinal hemorrhages Biochemistry Cotton wool spots Homocysteine Optical Biometry (Pre/Post) Lipids (LDL, HDL, TGs) Globe axial length Serum Insulin HbA1c Fasting serum glucose Fitness MVO2 (max oxygen uptake) 19

Cardiovascular Physiology Background Blood Vessel Compliance webschoolsolutions.com Venous compliance is approximately 30 times larger than arterial compliance Starling Equation: hydrostatic and oncotic forces (the so-called Starling forces ) in the movement of fluid across capillary membranes ffden-2.phys.uaf.edu http://en.wikipedia.org/wiki/Starling_equation#cite_note-1 20