Emergency Medical Response in Space Tourism

Reo Takizawa¹, Rinka Shimizu², Satoshi Oda², Abbauzadeh Daniel Ariya²,
Takeru Kayahara², Saki Shioya², Ayami Kawahara², Shuuhei Yamaguchi², Yudai Yamashita²,
Yuko Kurosaka², Yuka Nagano², Junichi Murakami², Takao Zama², Ryuta Nakamura²,
Tatsuya Tanaka³, Aiko Oka⁴, Sasagu Kurozumi⁵, Jun Horiguchi⁵

¹Department of Vascular Surgery, Saitama Prefectural Cardiovascular and Respiratory Center
²School of Medicine, International University of Health and Welfare, Japan
³Department of Neurosurgery, International University of Health and Welfare
⁴Department of Otorhinolaryngology, International University of Health and Welfare
⁵Department of Breast Surgery, International University of Health and Welfare

ABSTRACT
　Space tourism is expected to flourish with several people venturing into space, including for short trips.　Medical emergencies in the space environment can be a major problem.　Strong connections between medical professionals and the aerospace industry are needed for safe space tourism.　 It is impossible to avoid all medical emergencies in a situation where several space travelers with various underlying diseases, such as hypertension and diabetes, will be participating.　Therefore, it is necessary to consider measures to be taken in the event of a medical emergency for travelers with underlying medical conditions.　Emergency response and disease risk management are critical for space travel.　However, few clinical results in space have been reported, and this is considered an important issue.　This article discusses medical emergencies that can occur during space travel.　It also compares and discusses those who are unsuitable for space travel from the perspective of air travel.

（Received:7 May, 2022　Accepted:20 December, 2022）

Key words:Human spaceflight, Emergency Medical Response, Space Tourism

I.　Introduction
　As space tourism flourishes, the need for space emergency services should also be considered.　Strong connections between medical professionals and the aerospace industry are needed for safe space tourism^1）.　 Common medical problems associated with space travel include minor trauma, burns, skin and musculoskeletal problems, respiratory problems, headaches, insomnia, and space sickness^2）.　A review of space emergency literature reveals that since the 1960s, space emergencies have been of interest to space medics as an extension of aviation medicine and to space flight trajectories^3-4）.　This is not from the medical point of view of emergency medical treatment in the space environment but is based on orbital calculations for the rapid return of sick astronauts to Earth, especially if the astronauts have been healthy up to now and can withstand the return even in a medical emergency.　However, when space travelers with various underlying diseases go to space, the availability of treatment in space must be considered a prerequisite.　A different medical response will likely be required for astronauts with underlying diseases than that required for healthy astronauts.　In addition, there may be travelers who are not suited for space travel.　The medical problems and risks of space travel are defined by the duration of the flight and the orbit.　The early years of commercial space travel are easily comparable to the problems of airplane travel, since suborbital spaceflight is assumed to be more than 100 km above mean sea level.　There are no medically binding criteria for determining a participant’s suitability for prospective commercial spaceflight, beyond guidelines from several aerospace specialty organizations^5-8）.　In this study, we examined the environmental similarities existing between air travel and space travel, and therefore, the similarities between medical conditions in the two situations.　Based on this we determined the cases that are not suitable for space travel.

II.　Current spaceflight and associated medical problems
　By its very nature, space emergency medical response requires international understanding and agreement from the perspective of legal development.　In other words, it is important to be able to transport a person to an appropriate medical facility in any country and under any circumstances in an emergency that requires an urgent return to Earth.　In the current space program, the U.S. and Russian research institutes are supporting low-Earth orbit missions with telemedicine, a medical support service from Earth enhanced by advanced telecommunication links^9）.　This service provides health care for astronauts and makes decisions such as emergency return to Earth in case of medical emergencies.
　Considering that an emergency return to Earth can take up to six hours, medical emergencies in the space environment can be a significant problem.　To avoid a situation requiring an emergency return to Earth, we aim to review various medical conditions and establish guidelines for space travelers who may require emergency medical care.　However, complete avoidance of such medical emergencies is impossible.　Therefore, it is necessary to consider countermeasures in the event of a medical emergency.
　In space tourism, the human body may be exposed to microgravity, high radiation, and low atmospheric pressure.　The International Space Station （ISS） has a microgravity environment （μG） of 10-6G to 10-4G, and the atmospheric pressure is regulated to 1 atm.　Oxygen and nitrogen gases are kept in constant circulation, which is a highly safe environment because it is similar to the Earth's environment except for the gravity environment.　The environment within an aircraft is comparable to that in the early low-earth-orbit space travel spacecraft.　At an altitude of 33,000 feet, the cabin air pressure is about 0.7 atmospheres, the temperature is 24℃, and the humidity is 0 to 20%.　In addition to the special environment, there are other concerns regarding the medical supplies and deployment of medical personnel during space travel.　A doctor is not always available onboard, and even if there is one, the medical supplies and equipment may be insufficient.　This situation has many parallels with in-flight medical care.　Therefore, it will be necessary to deploy crew members with specialized medical training in the event of an emergency and ensure the availability of sufficient medical equipment to deal with trauma and other injuries.　However, the medical equipment, supplies, and hardware for use in space must mthe eet strict requirements of the remote and isolated space environment and are not easy to create^10）.　In addition, the actual treatment of patients requires the immobilization of physicians, patients, and supplies in microgravity and the use of a medical device to provide medical care in a remote environment.　Maintaining a sterile environment and disposal of medical waste must also be considered^11）.
　Situations requiring emergency medical care during space travel are expected to include the following
　（1） Accidents resulting from equipment failure on passenger aircraft.
　（2） Accidents or conditions caused by the external environment.
　（3） Medical emergencies caused by the personal constitution （including illness）.
　I would like to first discuss two technical issues that are particularly important in relation to space medicine: atmospheric pressure and gravity.　This problem corresponds to （1） of the above-mentioned situations.　Decompression sickness （DCS） is a problem during civilian space stays because of emergencies, such as spacecraft damage.　Air leaks due to spacecraft damage cause rapid depressurization and a hypoxic environment inside the spacecraft.　DCS occurs when a rapidly decreased pressure causes gases usually dissolved in blood or tissue to form bubbles in blood vessels.　Bubbles are detected in the blood at supersaturated pressures of 0.3-0.4 atmospheres^12）.　Typical DCS symptoms include pain, neurological symptoms, and in severe cases, death.　Joint pain is common in aircraft-associated DCS.　Serious respiratory impairment is suffered by <2% and neurological impairment by 5%-7% of patients.　Free gas bubbles can occur in any tissue and cause systemic embolism and inflammatory reactions^13）.　DCS treatment involves the administration of high concentrations of oxygen and rapid fluid resuscitation to maintain intravascular volume.　Additionally, the development of space-supplied life jackets for DCS prevention is necessary.　The term “time of useful consciousness” has been previously used to describe the time required for a person to lose the consciousness required for taking specific actions, such as evacuation, after being depressurized.　The considered period is between 10 and 15 seconds.　This is a phenomenon that both rescuers and medical personnel must be aware of to save lives.　Rescuing a rescuer in an extremely depressurized environment requires an appropriate response within the time of useful consciousness.　With an understanding of these conditions, rescuers must attempt to prevent proper decompression and pressurize the rescuer in need.
　The first external factor that affects space travelers when they venture beyond Earth is the change in gravity.　This problem corresponds to （2） of the above-mentioned situations.　The ISS is subject to microgravity, which is one millionth the gravity on Earth.　Previous space medicine research has shown that the effects of microgravity on humans are mainly noticeable in the cardiovascular, musculoskeletal, and neurosensory systems.　The main changes under microgravity in the body's fluid and circulatory systems are, a decrease in intravascular volume, which occurs within a few days and establishes new homeostasis.　This movement of peripheral fluid to the trunk is called the fluid shift.　Therefore, it is considered to be of sufficient concern in the presence of serious circulatory disease.
　Gravity is expected to have a more significant effect in a terrestrial environment.　Approximately 50% of astronauts experience space sickness in the early stages of microgravity exposure, likely caused by dysfunction in the equilibrium sense organs and increased intracranial pressure^14）.
　When a situation arises that requires emergency medical attention, the first principle of life-saving treatment is to secure an intravenous line that will provide a pathway for medication according to the condition.　 However, in a microgravity environment, specialized equipment may be required to administer fluids because of the difference in pressure between the intravenous line and venous pressure that exists in the veins.　Currently, no institution has developed such equipment.　Hemorrhage is a major cause of death from trauma on Earth.　Since saline is the only intravenous fluid that can be used on the Space Shuttle and ISS, it is necessary to discuss the introduction of new infusion methods in the future^15）.
　Common medical problems associated with space travel include minor trauma.　In terms of surgical procedures, current space launch programs provide astronauts with 20-60 hours of medical education, including simple suture training and deployment of basic medical supplies^16）.　During the NeuroLab shuttle mission using rats, astronauts showed that intramuscular anesthesia, dissection, hemostasis, and wound closure were possible and less difficult than in a 1 G environment^17）.　Emergency treatment for minor trauma in early low-earth orbit space travel is possible with some training.　However, the ability to handle large numbers of space tourists may be a problem.
　Although the risks associated with （3）, the individual's constitution, and the urgency associated with the disease, are considered different for each disease, the conditions that are generally considered unsuitable for air transport are may not recommend for aggressive space travel as an area of space emergency medicine^18）.
　Airlines indicate on their MEDICAL INFORMATION FORM （MEDIF） that a user is not suitable for air travel, and we have modified this form to include the following information for users who are not suitable for early space travel. （Table.）
　The three situations listed above apply to all space travelers and are therefore considered extremely important factors.　They are not sufficient and require further study.
　The medications that are used during spaceflight are currently quite limited.　Medicines can be used during space travel, but are mainly drugs for emergencies such as cardiopulmonary arrest and tranquilizers and are not suitable for internal use for space travelers with various co-morbidities.
　Medications are an important component of the risk management plan for astronaut health care during spaceflight.　However, little is understood about the current use and efficacy of medications during spaceflight, drug stability, and changes in drug concentrations during spaceflight^19）.　Another problem is that the need for emergency medical care in space travel is not addressed.　Medications for patients with hypertension, hyperlipidemia, and diabetes and respiratory inhalers for asthma patients are necessities for space travel.　Currently, the details on the mechanisms of these drugs and their effects on sick patients in the space environment have not been;therefore, the efficacy and hemodynamics of these drugs under microgravity conditions needs to be clarified in the future.

Table　Airlines indicate on their MEDICAL INFORMATION FORM （MEDIF） that a user is not suitable for air travel, and we have modified this form to include the following information for users who are not suitable for early space travel.

a）　Severe heart failure, cyanosis, myocardial infarction （within 6 weeks after the attack）

b）　Newborns and infants under 7 years of age

c）　Pregnant women who are within 4 weeks of their expected delivery date

d）　Anemia presenting with Hb less than 8 g/dl

e）　Severe otitis media with Eustachian tube obstruction

f）　Recently developed idiopathic pneumothorax or pyothorax.

g）　mediastinal tumor, extremely large hernia, intestinal obstruction, increased intracranial pressure, skull fracture

h）　Mental illness, alcohol, or other intoxication that may cause harm to self or others

i）　Recently operated on, unhealed wounds, postpartum women

j）　Extensively medullary type, gray myelitis not yet one month since the onset of illness

k）　Statutory and designated infectious diseases and pseudo infections, open tuberculosis, and other acute infections that may be contagious

l）　Infectious skin diseases

m）　Hemoptysis, hematemesis, hemorrhage, vomiting

III.　Conclusions
　At present, research on space medicine advancement is predominantly focused on health care for healthy astronauts.　Therefore, space medicine research focusing on the care of such individuals needs to be carried out.　However, considering that the space tourism industry is expected to develop in the future, there will be instances of civilians with several diseases participating in low earth-orbit space travel.　Currently, there are no medical criteria to determine a participant's suitability for commercial spaceflight other than the guidelines of a few aerospace professional organizations.　Additionally, it should be noted that some prospective space travelers may, unfortunately, be unfit for space travel, and regulations regarding the same should be established.
　Moreover, the methods to anticipate and respond to medical emergencies that may occur during space travel should be taken into consideration.　It is also important to consider the drugs that may be needed and the safety of their administration in the space environment.　Furthermore, in a space environment, the medical care needs to be provided with limited water and other resources due to a shortage of supplies and human resources.　In addition, it may be difficult to station medical personnel on all spacecrafts;thus, the development of telemedicine systems using digital technology is crucial.　In the event of an emergency return of a patient to the Earth, it is also necessary to develop a system that can transport the patient to an appropriate medical facility regardless of the location of the spacecraft landing.

Corresponding author:Reo Takizawa
　　　　　　　　　　　　1696 Itai, Kumagaya, Saitama 360-0197, Japan
　　　　　　　　　　　　Department of Vascular Surgery, Saitama Prefectural Cardiovascular and Respiratory Center
　　　　　　　　　　　　TEL:+81-48-536-9900
　　　　　　　　　　　　FAX:+81-48-536-9926
　　　　　　　　　　　　E-mail:reo.takizawa@gmail.com

1）	Stepanek J, Blue RS, Parazynski S:Space Medicine in the Era of Civilian Spaceflight.　N Engl J Med., 380, 1053-1060, 2019.
2）	Gontcharov IB, Kovachevich IV, Pool SL, Navinkov AL and Barratt MR:Medical care system for NASA-Mir spaceflights.　Aviat Space Environ Med., 73, 1219-1223, 2002.
3）	Campbell PA:Earthman, spaceman, universal man?, Pageant Press, 1965.
4）	Benson OO and Strughold H:Physics and medicine of the atmosphere and space;the proceedings of the Second International Symposium on the Physics and Medicine of the Atmosphere and Space, Wiley, 1960.
5）	Aerospace Medical Association Task Force on Space Travel:Medical guidelines for space passengers.　Aviat Space Environ Med., 72, 948-950, 2001.
6）	Rayman RB, Antun?ano MJ, Garber MA, et al.:Medical guidelines for space passengers ─ II.　Aviat Space Environ Med., 73, 1132-1134, 2002.
7）	Human space flight requirements for crew and space flight participants:final rule.　Washington, DC:Department of Transportation, Federal Aviation Administration, 2006.　https://www.federalregister.gov/documents/2006/12/15/E6-21193/human-space-flight-requirements-for-crew-and-space-flight-participants （Accessed Nov. 25, 2022）
8）	Center of Excellence for Commercial Space Transportation.　Flight crew medical standards and spaceflight participant medical acceptance guidelines for commercial space flight.　June 30, 2012
9）	Harnett BM, Doarn CR, Russell KM, Kapoor V, Merriam NR, and Merrell RC, et al.:Wireless telemetry and Internet technologies for medical management:a Martian analogy.　Aviat Space Environ Med, 72, 1125-1131, 2001.
10）	Houtchens BA:Medical-care systems for long-duration space missions.　Clin Chem, 39, 13-21,1993.
11）	Campbell MR, Dawson DL, Melton S, Hooker D and Cantu H:Surgical instrument restraint in weightlessness.　Aviat Space Environ Med, 72, 871-876, 2001.
12）	Ikeda T, Okamoto Y, Hashimoto A:Bubble formation and decompression sickness on direct ascent from shallow air saturation diving.　Aviat Space Environ Med, 64, 121-112, 1993.
13）	Lawley JS, Petersen LG, Howden EJ, Sarma S, Cornwell WK, Zhang R, Whitworth LA, Williams MA, Levine BD:Effect of gravity and microgravity on intracranial pressure.　J Physiol, 595, 2115-2127, 2017.
14）	Warren BA, Philp RB, Inwood MJ:The ultrastructural morphology of air embolism:platelet adhesion to the interface and endothelial damage.　Br J Exp Pathol, 54, 163-172, 1973.
15）	Kirkpatrick AW, Dulchavsky SA, Boulanger BR, Campbell MR, Hamilton DR, and Dawson DL:Extraterrestrial resuscitation of hemorrhagic shock:fluids.　J Trauma, 50, 162-168, 2001.
16）	Barratt M:Medical support for the International Space Station.　Aviat Space Environ Med, 70, 155-161, 1999.
17）	Campbell MR, Williams DR, Buckey JC, Jr and Kirkpatrick AW:Animal surgery during spaceflight on the Neurolab Shuttle mission.　Aviat Space Environ Med, 76, 589-593, 2005.
18）	Kato K, Iwao Y:Air Transportation of Patients with Respiratory Failure （In Japanese）.　Kokyu To Junkan （Respiration and Circulation） 42（4）, 349-352, 1994.
19）	Blue RS, Bayuse TM, Daniels VR, et al.:Supplying a pharmacy for NASA exploration spaceflight:challenges and current understanding.　NPJ Microgravity, 5, 14, 2019.