Chapter 7

Medical Operations in Space

Delivering healthcare in microgravity: from routine monitoring to emergency medicine

The Challenge of Space Medicine Practice

Providing medical care in microgravity presents unique challenges. Diagnostic procedures that rely on gravity (like chest auscultation or blood pressure measurement) work differently. Treatment modalities must be adapted—injections, IVs, wound care, and medication administration all require modified techniques. Emergency procedures like CPR are nearly impossible in traditional form. And medical supplies are limited to what can be launched, with resupply taking months on deep space missions.

ISS medical operations represent the culmination of decades of flight medicine experience. The medical system includes preventive health monitoring, diagnostic capabilities, treatment resources, and protocols for emergencies ranging from minor injuries to life-threatening conditions. Understanding these systems provides insight into the current state of space medicine and future requirements for exploration missions.

The ISS Medical Kit and Pharmaceuticals

The ISS Health Maintenance System (HMS) includes several categories of medical supplies. The primary medical kit contains diagnostic equipment, treatment supplies, and medications for common medical issues. Specialized kits address dental emergencies, burns, eye injuries, and trauma. A surgical kit provides capability for emergency procedures.

Medical Kit Type	Contents	Intended Use	Last Resupply Cycle
Crew Medical Restraint System (CMRS)	Body restraints, equipment mounts	Secure patient and provider during procedures	Permanent hardware
Crew Health Care System (CHeCS)	Diagnostic devices, monitoring equipment	Routine health assessments	Every 6 months
Pharmacy	200+ medications	Acute and chronic illness treatment	Every 6-12 months
Emergency Medical Kit	Resuscitation drugs, airways, IV supplies	Life-threatening emergencies	Every 6 months
Surgical Kit	Scalpels, sutures, drains, instruments	Emergency surgical procedures	Rarely replaced

Pharmaceutical Formulary

The ISS pharmacy contains over 200 medications addressing a wide range of conditions. Categories include analgesics (pain relief), antibiotics, antiemetics (anti-nausea), cardiovascular drugs, gastrointestinal medications, topical treatments, and psychoactive medications. All medications are packaged in single-use containers to minimize contamination and waste.

Diagnostic Capabilities

Ultrasound: The Swiss Army Knife

Portable ultrasound has revolutionized ISS medical care. Without X-ray or CT capability (too heavy, radiation exposure concerns), ultrasound provides real-time imaging for numerous applications: cardiac assessment, abdominal examination, vascular access guidance, trauma evaluation (FAST exam for internal bleeding), musculoskeletal injuries, and even SANS optic nerve imaging.

Astronauts receive extensive ultrasound training, guided by ground-based experts via telemedicine. The Advanced Diagnostic Ultrasound in Microgravity (ADUM) program demonstrated that non-physician astronauts can perform quality exams with remote guidance. This capability will be essential for autonomous Mars missions where real-time ground support isn't possible.

Laboratory Diagnostics

Limited laboratory analysis is available on ISS. Devices can measure basic chemistry (glucose, electrolytes), complete blood counts, urinalysis, and microbial culture. More sophisticated testing requires returning samples to Earth—impractical for time-sensitive diagnoses or distant missions. Future capabilities may include:

• Lab-on-a-chip devices: Miniaturized analyzers using microfluidics to perform comprehensive blood chemistry, immunoassays, and genetic testing with tiny sample volumes
• Biomarker panels: Arrays measuring multiple proteins, metabolites, or nucleic acids simultaneously to diagnose infections, organ dysfunction, or radiation damage
• Continuous monitoring: Wearable biosensors tracking vital signs, biomarkers, and physiological state in real-time

Diagnostic Modality	Current ISS Capability	Limitations	Mars Mission Needs
Imaging	Ultrasound (cardiac, abdominal, vascular)	No X-ray, CT, or MRI	Portable CT or advanced ultrasound AI
Laboratory	Basic chemistry, CBC, urinalysis, culture	Limited panel, manual processing	Comprehensive lab-on-chip, automated
Vital Signs	BP, HR, SpO₂, temp, ECG	Intermittent, manual	Continuous wearable monitoring
Pathogen ID	Culture-based (days)	Slow, limited organisms	Rapid PCR/sequencing (hours)

Telemedicine and Ground Support

ISS crews have continuous access to flight surgeons and specialists on Earth via voice, video, and data links. This telemedicine capability allows ground-based physicians to guide astronauts through complex procedures, interpret diagnostic data, and make treatment decisions. The Crew Medical Officer (CMO)—an astronaut with advanced medical training—serves as the onboard medical expert, but can consult with terrestrial specialists for challenging cases.

Common Medical Events in Space

Medical issues aboard ISS are tracked and analyzed. The most frequent conditions include:

• Minor trauma: Cuts, bruises, abrasions from collisions with hardware in cramped spaces (most common)
• Rashes and skin irritation: Contact dermatitis, fungal infections, pressure sores
• Upper respiratory infections: Common colds and viral syndromes (limited transmission due to small population)
• Headaches: Often related to carbon dioxide levels, stress, or dehydration
• Gastrointestinal complaints: Constipation, diarrhea, nausea
• Musculoskeletal pain: Back pain, muscle strains from exercise or EVAs
• Eye irritation: Foreign bodies, conjunctivitis
• Dental issues: Toothaches, lost fillings (rare but problematic)

Most conditions are minor and managed with conservative treatment. Serious medical events—defined as those requiring immediate intervention, evacuation consideration, or causing significant mission impact—occur at a rate of approximately 1 per 1,000 person-days. For a six-month mission with 6 crew members, this translates to roughly 1 serious medical event per mission.

Emergency Medical Procedures

Cardiopulmonary Resuscitation in Microgravity

Traditional CPR relies on a firm surface beneath the patient and gravity to aid compressions. In microgravity, both are absent. Multiple CPR techniques have been developed and tested in parabolic flight:

• Handstand method: Rescuer braces feet against ceiling, wraps legs around patient, performs chest compressions
• Reverse bear hug: Rescuer behind patient, performs compressions while another crew member stabilizes
• Evetts-Russomano method: Rescuer straddles patient's thighs, uses elastic strap around patient's torso for counter-pressure

All methods are awkward and physically exhausting compared to terrestrial CPR. Automated chest compression devices designed for microgravity are being developed but aren't yet deployed. The reality is that cardiac arrest in space has a very poor prognosis—prevention through cardiovascular screening and monitoring is paramount.

Trauma and Hemorrhage Control

Controlling bleeding in microgravity is challenging. Blood doesn't flow or pool—it forms spherical droplets that float and can contaminate equipment or be inhaled. Pressure dressings, tourniquets, and hemostatic agents are available, but surgical intervention would be extremely difficult.

Surgical Capability

Current ISS capability includes minor procedures: suturing lacerations, incision and drainage of abscesses, tooth extractions, and basic wound debridement. Major surgery—appendectomy, exploratory laparotomy, or thoracotomy—would be exceptionally difficult but may be attempted in a dire emergency.

Challenges include:

• Containment: Blood and fluids must be suctioned or absorbed; cannot be allowed to float
• Patient stabilization: Requires specialized restraint system
• Anesthesia: General anesthesia in microgravity is complex; airway management differs
• Sterility: Maintaining sterile field when objects float is challenging
• Team coordination: Surgeon, assistant, and anesthetist all floating and tethered
• Limited training: No crew member is likely to be a trained surgeon; ground guidance essential

Research into space surgery uses animal models, simulations, and robotic assistance. Teleoperated surgical robots—where a ground-based surgeon controls instruments aboard the spacecraft—may be feasible for ISS with minimal communication delay. For Mars, autonomous or semi-autonomous robotic systems would be necessary.

Preventive Medicine and Health Monitoring

The best medical treatment is prevention. ISS crews undergo regular health monitoring including:

• Daily vital signs: Blood pressure, heart rate, temperature, weight
• Weekly questionnaires: Sleep quality, mood, fatigue, symptoms
• Monthly examinations: Comprehensive physical exam by CMO with ground physician participation
• Quarterly assessments: Ultrasound exams, ECG, pulmonary function, vision testing
• Pre and post-flight: Comprehensive medical evaluations including imaging, laboratory work, fitness testing

This intensive monitoring allows early detection of medical issues and tracking of physiological changes. Data feeds into NASA's Longitudinal Study of Astronaut Health (LSAH), building a database of spaceflight health effects across thousands of person-days.