Space Medicine

1

Operational Space Medicine

Douglas Hamilton, M.D, Ph.D

Wyle Laboratories NASA Johnson Space Center

Houston, TX, USA

Star Trek TV Series. Photo Paramount Pictures

Kluwer Academic Publishers • Copyright © 2003 • All rights reserved

Fundamentals of Space Medicine — Chapter 7

Space Medicine

2Key Concepts

• Space medicine: What is it?

• What are the health hazards of spaceflight. Comparison with analog environments

• Medical selection of astronauts and prevention of health hazards

• In-flight countermeasures

• Treatment of medical events in space. The onsite medical facility. Emergency and rescue

Space Medicine

3Space Medicine

• What it is– It involves proactive and reactive care of humans to

optimize physical, physiological, and mental well-being, within the unique constraints of an extreme environment

• What it isn’t

– Space Medicine is different from Space Physiology

– Many aspects of adaptation to weightlessness are peculiarities, not necessarily pathology

– Even if not pathological, changes may alter the way a disease presents or may increase risks for a given medical problem

Photo NASA

Space Medicine

4Space Medicine

“Your neuro-vestibular, cardio-vascular, and musculo-skeletal systems can’t support you anymore.”

Space Medicine

5Operational Space Medicine

• Selection and Prevention are the primary means of maintaining crew health and performance

• Countermeasures are used when Selection and Prevention are unable to mitigate the deleterious effects of spaceflight

• Treatment is used when Selection, Prevention, and Countermeasures are unable to prevent or mitigate illness or injury

• Rehabilitation: return to flight status

Space Medicine

6History of Space Medicine

Photos NASA

Space Medicine

7Astronaut Selection

• Medical history

• Examination

– Physical exam

– Cardio-pulmonary

– Ear-Nose-Throat

– Ophtalmological

– Dental

– Neurological

– Psychiatric

– Radiographic

– Laboratory

• Others

– U.S.:

• Drug screen, microbiological, pregnancy, STD

– Russia:

• Decompression and hypoxia

• Centrifuge for +Gz and +Gx resistance

• Rotating chair

• Tilt table studies

• LBNP

• Heat stress

• Parabolic flight

Space Medicine

8Astronaut Training

Jet training

Emergency egress training

Medical training

Water training

Pho

tos

NA

SA

Pho

to C

NE

SP

hoto

NA

SA

Space Medicine

9Risk Assessment

• Most tests have a poor ability for detecting the presence of disease in very healthy individuals

• There are almost no tests which are designed to select-out the occurrence of pathology (illness) over the next three years. This is a problem for selecting a crew for a Mars Mission

• All risks cannot be predicted

Movie: 09_AlienSong

Space Medicine

10Common Medical Events

• Space Motion Sickness: count on 50-70%

• Foreign bodies in the eye: particles do not “settle out”

• Decompression-related disorders: especially with active EVA schedule

• Toxic inhalation: e.g. from chemicals/reagents involved in investigations, pyrolysis products from fire, propellants

• Kidney stones: risk due to mobilization of calcium from skeleton, and possibly other factors

• Radiation: identified as the major career-limiting exposure for astronauts

Photo NASA

Space Medicine

11Less Likely Medical Events

• Cardiovascular events: rigorous screening process during astronaut selection, flight certification

• Major fractures: largely, forces which lead to such events terrestrially, such as vehicle accidents and falls, not present

• Infectious disease: after a certain disease free “incubation period” no new pathogens introduced into a small group (however, there are also immune system changes with unclear effects on overall risk)

Note: all the above represents a large portion of events prompting visits to medical care facilities on Earth

Space Medicine

12Source of Ionizing Radiation in Space

• Solar energetic particles emitted from the sun during solar flares

• Particles trapped by the Earth’s magnetic field in the Van Allen belts,

• Galactic cosmic radiation which crosses the galaxy

Each of these sources consists of all the types of space radiation, but at different energies and in different relative proportions

Space Medicine

13Acute Radiation Syndrome

Dose (Sv) Probable Medical Effects0.1-0.5 No effects except minor blood changes0.1-1 5-10% subjects experience nausea or vomiting, fatigue for 1-2 days, slight

reduction in white blood cells1-2 25-50% nausea/vomiting, with some other symptoms, 50%

reduction in white blood cells2-3.5 75-100% nausea/vomiting, fever, with anorexia, diarrhea, minor

bleeding, 75% reduction in all blood elements. 5-50% subjects will die3.5-5.5 100% nausea/vomiting, fever, bleeding diarrhea, emaciation. Death of 50-

90% in 6 weeks. Survivors require 6 months convalescence5.5-7.5 100% nausea/vomiting in 4 hours. 80-100% die7.5-10 Severe nausea/vomiting for 3 days. Death within 2.5 weeks10-20 Nausea/vomiting within 1 hour. 100% die within less than 2

weeks45 Incapacitation within hours. 100% die within 1 week

Space Medicine

14Radiation Exposure

• Exposure Limits for Ionizing RadiationBFO Eye Skin

30 Days 0.25 1 1.5 Annual 0.5 2 3 Career 1-4* 4 6

*The career dose-equivalent (in Sievert, Sv) is based upon a maximum 3% lifetime risk of cancer mortality. BFO: blood-forming organs

• Measured Radiation Dose during Spaceflight

Mission Absorbed Dose(mGy) Dose Equivalent (Sv)Space Shuttle 2-4 0.005 Sv(7-day mission orbiting Earth at <450 km)

Space Shuttle 5.2 0.05 Sv(8-day mission orbiting Earth at >450 km)

Apollo-14 11.4 0.03 Sv(9-day mission to the Moon)

Skylab-4 77.4 0.178 Sv(84-day mission orbiting Earth at 430 km, 28.5 deg inclination)

Mir 146 0.584 Sv(1-year mission orbiting Earth at 400 km, 51.5 deg inclination)

Space Medicine

15Radiation Shielding

Time Event06:21 Optical flare observed13:00 30-day limit exceeded for skin and optical lens14:00 30-day limit exceeded for BFO; annual limit

exceeded for lens15:00 Annual limit exceeded for skin16:00 Annual exceeded for BFO; Career exceeded for lens17:00 Career limit exceeded for skin

• Effects of a Solar Flare Event with 2 g/cm2 shielding (Aug’72)

Shield Thickness BFO Skin Lens0.2 (g/cm2) 6.0 3.0 1.91.0 (g/cm2) 6.3 3.5 2.45.0 (g/cm2) 8.9 8.0 6.5

• Time to reach 30-day limit (hours)

Photo NASA

Space Medicine

16Rules in Space Medicine

• “Common things occur commonly”

• Mission-specific operational hazards: e.g., harmful environment, toxic substances, etc.

• Injury / illness is occurring in a body which is adapting to microgravity

• Manpower is in short supply

• In-flight, the crew is on its own with limited support from Earth

Photo CNES

Space Medicine

17Medical Hardware Selection

• Weight/volume: as small and compact as possible

• Simple and intuitive to use; training will be limited

• Power/data needs: add immensely to complexity; non-powered if possible

• Long shelf-life, "bullet proof” technology desired

• Supports identified standards of care; must meets clinical management analysis, e.g. provides useful information

• Modular, easy to replace and upgrade components

• Think 0-G or partial G as needed

Photo NASA

Space Medicine

18ISS Crew Health Care System (CHeCS)

• Health Maintenance System

– Body Restraint System

– Cardiac defibrillator

– Advanced Life Support Pack

– Human Research Facility

• Gas Analyzer System

• Heart and vascular ultrasound

• Abdominal ultrasound, deep organ

• Gynecological ultrasound

• Muscle and tendon ultrasound

• Transcranial ultrasound

• Environmental Health System

• Countermeasures System

– Treadmill

– Cycle ergometer

– Resistive exercise

First ultrasound examination (lungs) performed on board

the ISS. Documents NASA

Movie: 18_lungs

Space Medicine

19Examples of Flight Medical Hardware

• Cardiac Defibrillator / Monitor

– Early electrical defibrillation correlates best with survival in event of cardiac arrest (many roads to ventricular fibrillation)

– It is no longer simple to apply force to defibrillator paddles; adhesive conductive pads are used

– Must provide insulation from delivered voltage and consider effects of electromagnetic interference (EMI) on sensitive avionics

Pho

to N

AS

A

Space Medicine

20Examples of Flight Medical Hardware

• Advanced Life Support Pack

– Accessibility and use strongly influence success / survival

– Medical waste, e.g., sharp needles must be carefully disposed

– Medications must be tracked and discarded when shelf-life exceeded

– Absorption of oral medications may be sensitive to digestive function, which may be altered in space

– Alternate routes of administration may be better for some drugs (intramuscular, intravenous, nasal)

Pho

tos

NA

SA

Space Medicine

21Advanced Life Support Pack

Document NASA

Deployment and utilization of the Advanced Life Support Pack on board the ISS

Movie: 21_contingency

Space Medicine

22Telemedicine

Care MedicalOfficer (CMO)

Onboard MedicalCare Facility

Injured or ill Crewmember

Telemedicine Link

Crew Surgeon

EngineeringSupport Consultants

Space Medicine

23Telemedicine Pack

• Voice / video communications both ways (private medical conferences, diagnostic and procedural aid)

• Continuous physiological monitoring (eases requirements on crew; ground personnel can analyze trends)

• Video Imaging– Eye– Ear, nose, throat– Skin

• Biomedical Monitoring– ECG– SpO2

– Blood pressure– Heart rate

• Electronic Stethoscope– Heart, lung, and bowel sounds

Photo NASA

Space Medicine

24Emergency and Rescue

• Response to an orbital medical event depends on 5 factors:

– Severity of illness / injury

– Capability of onboard medical system

– Ability of surgeon to assist during medical event

– Level of skill / training of onboard medical officer

– Ease / feasibility of medical evacuation to Earth

• Crew Medical Officer

– 3 -7 crewmembers on ISS

– Crew Medical Officer (CMO) on ISS is usually not a physician

– CMO receives 40-60 hours of medical training completed at least 3 months prior to flight

– Trained to recognize, treat, and stabilized acute injury

– Trained to prepare patient for transport

Space Medicine

25Treatment

• Treatment structure highly desirable

• Requires means of transporting patient

• Necessary medical hardware in proximity

• Restraint function integrated with diagnostic and therapeutic systems

• Some new procedures need to be adapted for microgravity (e.g., CPR)

Documents NASA

Movie: 25_restraint

Space Medicine

26Surgery in Space

• Operator and patient restraints

• Instrument deployment and fixation

• Sterile environment

– Increased population of antibiotic resistant bacteria

– Decreased immune function documented in space

• Lighting and exposure

• Control of atmosphere contamination (bleeding)

• Decreased proprioceptive (muscle and skin) sensation

• Time delay for telesurgery

Photo NASA

Space Medicine

27Emergencies — Soyuz

Photos NASA

Space Medicine

28Emergencies — Egress

Photos NASA

Space Medicine

29Additional Reading

• Billica RD, Simmons SC, Mather KL, et al. (1996) Perception of the medical risk of spaceflight. Aviat Space Environ Med 67: 467-473

• Clément G (2003) Fundamentals of Space Medicine. Dordrecht: Kluwer Academic Publishers

• Lane HW, Schoeller D (eds) (1999) Nutrition in Spaceflight and Weightless Models. Boca Raton, FL: CRC Press

• Wilson WJ, Miller J, Konradi A, Cucinotta FA (eds) (1997) Shielding Strategies for Human Space Exploration. NASA CP-3360 Washington, DC: NASA

• Institute of Medicine (2001) Safe Passage: Astronaut Care for Exploration Missions. Ball HR, Evans CH, Ballard JR (eds) Washington, DC: National Academy Press

• International Workshop on Human Factors in Space. Aviat Space Environ Med 71, Number 9, Section II (Supplement) 2000

• National Research Council (1996) Radiation Hazards to Crews of Interplanetary Missions. Task Group on the Biological Effects of Space Radiation. Washington, DC: National Academy Press