Microgravity effects on fine motor skills: tying surgical knots during parabolic flight

INTRODUCTION: The health provider on a space exploration mission cannot evacuate a patient to Earth. Contingency plans for medical intervention must be designed for autonomy. This study measured the effect of microgravity on performance of fine motor skills such as basic surgical tasks. METHODS: Eight subjects, six with medical and two with non-medical backgrounds, were evaluated during parabolic microgravity flights aboard NASA's KC-135. We evaluated their skill in tying surgical knots on simulated skin made of silicone using standard techniques for minimally invasive surgery. LabView software was developed to archive forces applied to the laparoscopic tool handles during knot-tying. Studies were controlled for medication (ScopeDex) and the aircraft environment. RESULTS: All participants completed the tests successfully. The data indicated that increased force was applied to the instruments and knot quality decreased during flight compared with ground control sessions. CONCLUSION: Specific metrics of surgical task performance are essential in developing education modules for providers of medical care during exploration-class missions.     

Sensorimotor performance and computational demand during short-term exposure to microgravity

INTRODUCTION: Previous research suggests that human sensorimotor performance depends both on task difficulty, and on the allocation of the brain's computational resources to the task. We employ this view to analyze the changes of sensorimotor performance during the microgravity episodes of parabolic flight. METHODS: There were seven subjects who participated before, during, and after exposure to the microgravity episodes of parabolic flight. They performed a tracking task with one hand, and a four-choice reaction time task with the other hand, either alone or concurrently. Overall performance scores across tasks were calculated. RESULTS: Overall single-task performance deteriorated by about 50% microgravity, with little sign of recovery during the flight. Overall dual-task interference was more than twice as great at the onset of microgravity than at the onset of the 1-G baseline, but converged toward that baseline within about 4.5 min. CONCLUSIONS: Our subjects accepted a consistently poor level of sensorimotor performance throughout exposure to microgravity. To maintain that level, they increased the allocation of computational resources to the tasks at the onset of microgravity, but an increase was no longer necessary after 4.5 min of microgravity exposure. We take the initial increase as evidence of a brief phase of sensorimotor adaptation.     

Performance of advanced trauma life support procedures in microgravity

BACKGROUND: Medical operations on the International Space Station will emphasize the stabilization and transport of critically injured personnel and so will need to be capable of advanced trauma life support (ATLS). METHODS: We evaluated the ATLS invasive procedures in the microgravity environment of parabolic flight using a porcine animal model. Included in the procedures evaluated were artificial ventilation, intravenous infusion, laceration closure, tracheostomy, Foley catheter drainage, chest tube insertion, peritoneal lavage, and the use of telemedicine methods for procedural direction. RESULTS: Artificial ventilation was performed and appeared to be unaltered from the 1-G environment. Intravenous infusion, laceration closure, percutaneous dilational tracheostomy, and Foley catheter drainage were achieved without difficulty. Chest tube insertion and drainage were performed with no more difficulty than in the 1-G environment due to the ability to restrain patient, operator and supplies. A Heimlich valve and Sorenson drainage system were both used to provide for chest tube drainage collection with minimal equipment, without the risk of atmospheric contamination, and with the capability to auto-transfuse blood drained from a hemothorax. The use of telemedicine in chest tube insertion was demonstrated to be useful and feasible. Peritoneal lavage using a percutaneous technique, although requiring less training to perform, was found to be dangerous in weightlessness due to the additional pressure of the bowel on the anterior abdominal wall creating a high risk of bowel perforation. CONCLUSIONS: The performance of ATLS procedures in microgravity appears to be feasible with the exception of diagnostic peritoneal lavage. Minor modifications to equipment and techniques are required in microgravity to effect surgical drainage in the presence of altered fluid dynamics, to prevent atmospheric contamination, and to provide for the restraint requirements. A parabolic simulation system was developed for equipment and procedure verification, physiological research, and possible crew medical officer training in the future.     

Surgical instrument restraint in weightlessness

BACKGROUND: Performing a surgical procedure during spaceflight will become more likely in the future as the duration of missions becomes longer. Only minimal surgical capability was available on previous missions since the definitive medical care time was short and the likelihood of a surgical event too low to justify carrying surgical hardware onboard. Early demonstrations of surgical procedures in the microgravity environment of parabolic flight indicated the need for careful logistical planning and restraint of surgical hardware. Human ergonomics also has more effect in microgravity than in the conventional 1-G environment. METHODS: Three methods of surgical instrument restraint--a Minor Surgical Kit (MSK), a Surgical Restraint Scrub Suit (SRSS), and a Surgical Tray (ST)--were evaluated in parabolic flight surgical procedures. RESULTS: The MSK was easily stored, easily deployed, and demonstrated the best ability to facilitate a surgical procedure in microgravity. CONCLUSION: Important factors in a surgical restraint system for microgravity include excellent organization of supplies, ability to maintain sterility, accessibility while providing secure restraint, ability to dispose of sharp items and biological trash, and ergonomic efficiency.     

Influence of the helicopter environment on patient care capabilities: flight crew perceptions

INTRODUCTION: Flight crew perceptions of the effect of the rotary-wing environment on patient-care capabilities have not been subject to statistical analysis. We hypothesized that flight crew members perceived significant difficulties in performing patient-care tasks during air medical transport. METHODS: A survey was distributed to a convenience sample of flight crew members from 20 flight programs. Respondents were asked to compare the difficulty of performing patient-care tasks in rotary-wing and standard (emergency department or intensive care unit) settings. Demographic data collected on respondents included years of flight experience, flights per month, crew duty position and primary aircraft in which the respondent worked. Statistical analysis was performed as appropriate using Student's t-test, type III sum of squares, and analysis of variance. Alpha was defined as p < 0.05. RESULTS: Fifty-five percent of programs (90 individuals) responded. All tasks were significantly rated more difficult in the rotary-wing environment. Ratings were not significantly correlated with flight experience, duty position, flights per month or aircraft used. CONCLUSIONS: We conclude that the performance of patient-care tasks are perceived by air medical flight crew to be significantly more difficult during rotary-wing air medical transport than in hospital settings.     

Basic life support in microgravity: evaluation of a novel method during parabolic flight

BACKGROUND: If a cardiac arrest occurs in microgravity, the aim of current emergency procedures is to treat the patient using a medical restraint system within 2 min. The patient may require treatment while medical equipment is being deployed. The capability for one person, unaided, to successfully perform cardiopulmonary resuscitation (CPR) is, therefore, of paramount importance. A new technique has been developed whereby the practitioner encircles the thorax of the patient with his/her legs to restrain the patient to allow CPR to be performed in microgravity. METHOD: Two investigators performed both this method (during parabolic microgravity) and traditional CPR (at +1 Gz) on an instrumented CPR mannequin. The mannequin was modified to ensure accurate chest compression and ventilation measurements during microgravity. RESULTS: The mean (+/-SE) depth and rate of chest compression were 44.0+/-4.99 mm and 68.3+/-17.0 compressions x min(-1) respectively. Although the mean microgravity rate of compression proved significantly less (p < 0.05) than the +1 Gz mean (97.1+/-3.4 compressions x min(-1)), chest compression depth did not differ (p > 0.05) from +1 Gz measures (43.6+/-0.59 mm). The mean (+/-SE) microgravity tidal volume (VT) was 491+/-50.4 ml, which also did not differ (p > 0.05) from +1 Gz values (507.6+/-11.5 ml). DISCUSSION: Although difficulties in performing this method during parabolic flight primarily affected compression rate, it may be possible to conduct basic life support using this technique in any microgravity environment.     

Biomedical results of the Space Shuttle Orbital Flight Test Program

On July 4, 1982 the Space Shuttle Columbia landed at Edwards Air Force Base, California, thus successfully completing the fourth and last in a series of Orbital Flight Tests (OFT) of the Space Transportation System (STS). The primary goal of medical operation support for the OFT was to assure the health and well-being of flight personnel during all phases of the mission. To this end, the crew health status was evaluated preflight, inflight and postflight. Biomedical flight test requirements were completed in the following areas: physiological adaptation to microgravity, cabin acoustical noise, cabin atmospheric evaluation, radiation dosimetry, crew exercise equipment evaluation and a cardiovascular deconditioning countermeasure assessment.     

On the practicality of emergency surgery during long-duration space missions

While discussions of the practicality of surgery in space often focus on technical issues, such as adapting instrumentation and procedures for use in microgravity, programmatic issues need to be addressed if meaningful capabilities for emergency surgery are to be considered for human exploration missions beyond low Earth orbit. Advanced technologies that have been evaluated, including simulation-enhanced training, telementoring, or robotic assistance, might help prepare or augment a crew medical officer, but a physician with advanced training and relevant experience will be needed if surgical capabilities beyond basic emergency aid are to be considered. Specific operational roles for physician-astronauts should be established.     

Training of flight nurses on fixed-wing air ambulance services

Introduction: The purpose of this study was to determine the background of fixed-wing air ambulance nurses, what level of training they receive before assignment as a flight nurse, and how closely supervised these fixed-wing air ambulance programs are by their medical directors.

Methods: In 1993, a retrospective statistical questionnaire was sent to 113 fixed-wing air ambulance programs. Chief flight nurses for all 113 fixed-wing air ambulance transport companies were requested to complete a written survey consisting of 17 multiple choice and fill-in-the-blank questions about previous experience, flight nurse qualifications, and content covered in their initial training program.

Results: Of 113 surveys, 72 (64%) responded. The majority (87%) of the flight crew were 30 to 39 years of age. The crew mix is RN/EMT-P in 49%, RN/RN in 25%, and RN/RT in 25%. Experience before flying showed emergency department/intensive care unit in 87% with 13% specialized to a specific type of patient care. The initial training in classroom hours was less than 21 hours in 50% of programs. Training programs were taught by the chief flight nurse in 75%, the medical directors in 74%, and outside organizations in 30%. Fifty-five percent of programs use pilots or other flight crew members to supplement initial training. Only eight of the programs did not have yearly refresher classes. Programs providing more extensive training appear to be affiliated with hospital-based services. Medical directors were involved with the everyday running of air medical transports in 35 of the pro grams (50%), 20 medical directors (28%) did monthly chart reviews only, and 12 (17%) were not involved with their programs. There were three responses to “Other” and two with no responses.

Conclusions: Although fixed-wing flight nurses appear to be medically experienced personnel with previous intensive care unit or emergency department experience, this survey would suggest that fixed-wing flight programs are variable in the amount of initial training, level of instructors, ongoing medical education, and involvement of the medical director. This survey indicates the need for increased standardization of continuing education, as well as increased involvement of medical directorship in fixed-wing air ambulance services.     

Sonographic detection of pneumothorax and hemothorax in microgravity

INTRODUCTION: An intrathoracic injury may be disastrous to a crew-member aboard the International Space Station (ISS) if the diagnosis is missed or delayed. Symptomatic or clinically suspicious thoracic trauma is treated as a surgical emergency on Earth, usually with immediate stabilization and rapid transport to a facility that is able to deliver the appropriate medical care. A similar approach is planned for the ISS; however, an unnecessary evacuation would cause a significant mission impact and an exorbitant expense. HYPOTHESIS: The use of ultrasound imaging for the detection of pneumothorax and hemothorax in microgravity is both possible and practical. METHODS: Sonography was performed on anesthetized pigs in a ground-based laboratory (n = 4) and microgravity conditions (0 G) during parabolic flight (n = 4). Aliquots of air (50-500 ml) or saline (10-200 ml) were introduced into the pleural space to simulate pneumothorax and hemothorax, respectively. RESULTS: The presence of "lung sliding" excluded pnemothorax. In microgravity, a loss of "lung sliding" was noted simultaneously in the anterior and posterior sonographic windows after 100 ml of air was introduced into the chest, indicating pneumothorax. The presence of the fluid layer in simulated hemothorax was noted in the anterior and posterior sonographic windows after 50 ml of fluid was injected into the pleural space. During the microgravity phase, the intrapleural fluid rapidly redistributed so that it could be detected using either anterior or posterior sonographic windows. CONCLUSION: Modest to severe pneumothorax and hemothorax can be diagnosed using ultrasound in microgravity.     

Jumping in simulated and true microgravity: response to maximal efforts with three landing types

BACKGROUND: Exercise is a promising countermeasure to the physiological deconditioning experienced in microgravity, but has not proven effective in eliminating the ongoing loss of bone mineral, most likely due to the lack of high-impact forces and loading rates during in-flight activity. We wanted to determine lower-extremity response to high-impact jumping exercises in true and simulated microgravity and establish if 1-G force magnitudes can be achieved in a weightless environment. METHODS: Jumping experiments were performed in a ground-based zero-gravity simulator (ZGS) in 1 G, and during parabolic flight with a gravity-replacement system. There were 12 subjects who participated in the study, with 4 subjects common to both conditions. Force, loading rates, jump height, and kinematics were analyzed during jumps with three distinct landings: two-footed toe-heel, one-footed toe-heel, and flat-footed. Gravity replacement loads of 45%, 60%, 75%, and 100% bodyweight were used in the ZGS; because of time constraints, these loads were limited to 60% and 75% bodyweight in parabolic flight. RESULTS: Average peak ground-reaction forces during landing ranged between 1902+/-607 and 2631+/-663 N in the ZGS and between 1683+/-807 and 2683+/-1174 N in the KC-135. No significant differences were found between the simulated and true microgravity conditions, but neither condition achieved the magnitudes found in 1 G. CONCLUSION: Data support the hypothesis that jumping exercises can impart high-impact forces during weightlessness and that the custom-designed ZGS will replicate what is experienced in true microgravity.     

Inflight application of three pilot workload measurement techniques

Three measures of workload were tested during 11 routine missions conducted by the NASA Kuiper Airborne Observatory: communications performance, subjective ratings, and heart rate. The activities that contributed to crewmember workload varied; the commander was responsible for aircraft control and navigation whereas the copilot handled communications with ATC and the astronomers. Ratings of workload, stress, and effort given by the two crewmembers were highly correlated and varied across flight segments, peaking during takeoff and landing. Since the pilots performed different tasks during each segment, their ratings appeared to reflect overall crew workload, rather than experiences specific to each pilot. Subjective fatigue increased significantly from takeoff to landing for all flights, although the increase was significantly greater as landing times shifted from 10:00 p.m. to 9:00 a.m. The type, source, number, and frequency of communications varied significantly across flight segments, providing an objective indicator of pilot workload. Heart rate was significantly higher for the aircraft commander than for the copilot. Although heart rate peaked for both positions during takeoff and landing, the amount of change was significantly greater for the aircraft commander. Subjective ratings of stress, workload, and mental effort were significantly correlated with heart rate and communications frequency but were unrelated to mission duration, rated fatigue, or pilot evaluation of performance.     

The effect of an in-flight, emergency training program on crew confidence

INTRODUCTION: Despite some progress, the air medical transport profession continues to experience widely publicized accidents that result in injuries and death to crew members and patients. An air medical crew member's experience, training and confidence may affect his or her ability to deal effectively with an in-flight emergency, and may also affect his or her behavior before and after the emergency. SETTING: A hospital-based, rural rotor- and fixed-wing program flying approximately 890 flights per year. Seventy-seven percent of these flights are interfacility. METHODS: A pretraining survey evaluated the experiences of air medical crew members and pilots. A 20-question assessment tool based on a 5-point Likert scale evaluated how confident the individuals were in their ability to react to in-flight emergencies. An extensive in-flight emergency training program was then conducted. Personnel were asked to complete the same questionnaire one month and six months after the training. RESULTS: On the pretraining questionnaire, flight crew members with neither prior training nor actual experience in in-flight emergencies showed the lowest level of confidence. Those with prior training, actual in-flight emergency experience or both, responded with higher levels of confidence. The mean confidence scores of the study participants increased from 82 pretraining to 89 at one month post-training and remained at the increased level six months after training. CONCLUSIONS: A training program focusing on in-flight, aircraft-related emergencies can increase the crew's confidence during such situations. This increase in confidence is most noticeable in those without previous training or experience and is maintained for at least six months. Several other benefits occur from the training program.     

Testing of the gas vortex culture stirrer under conditions of short-term microgravity

Functional testing of the bioreactor for stirring culture in microgravity was performed during the microgravity episodes aboard research airplane Il-76 following the Kepler parabolic flight path. The attempt to produce the gas vortex stirring effect in a given liquid volume was a failure. Nonetheless, the stirrer ventilator is capable to agitate liquid acting as a mechanical stirrer.     

Human health and performance for long-duration spaceflight

Future long-duration spaceflights are now being planned to the Moon and Mars as a part of the "Vision for Space Exploration" program initiated by NASA in 2004. This report describes the design reference missions for the International Space Station, Lunar Base, and eventually a Mars Expedition. There is a need to develop more stringent preflight medical screening for crewmembers to minimize risk factors for diseases which cannot be effectively treated in flight. Since funding for space life sciences research and development has been eliminated to fund program development, these missions will be enabled by countermeasures much like those currently in use aboard the International Space Station. Artificial gravity using centrifugation in a rotating spacecraft has been suggested repeatedly as a "universal countermeasure" against deconditioning in microgravity and could be an option if other countermeasures are found to be ineffective. However, the greatest medical unknown in interplanetary flight may be the effects of radiation exposure. In addition, a Mars expedition would lead to a far greater level of isolation and psychological stress than any space mission attempted previously; because of this, psychiatric decompensation remains a risk. Historically, mortality and morbidity related to illness and injury have accounted for more failures and delays in new exploration than have defective transportation systems. The medical care system on a future Mars expedition will need to be autonomous and self-sufficient due to the extremely long separation from definitive medical care. This capability could be expanded by the presence of a physician in the crew and including simple, low-technology surgical capability.     

CPR effectiveness in microgravity: comparison of three positions and a mechanical device

BACKGROUND AND OBJECTIVE: Cardiopulmonary resuscitation (CPR) in microgravity via closed chest compression is thought to be possible by several techniques. This study examined the handstand, side, and waist straddle maneuvers, and a bear hug technique in performing CPR and meeting American Heart Association (AHA) recommendations in microgravity. We also hypothesized that one rescuer using a CPR bellows adjunct device is equivalent to two rescuers. METHODS: A pre-intubated mannequin model resting on the crew medical restraint system from the International Space Station was instrumented with transducers to measure airway pressure and chest compression depth. Microgravity conditions were provided through repetitive parabolic flight on the KC-135A. On identifying the most effective position, standard two-rescuer CPR was compared with one-rescuer CPR augmented with a bellows-on-sternum CPR adjunct device (Kendall CardioVent, Kendall Medizinische Erzeugnisse GMBH, Neustadt/Donau, Germany). RESULTS: Handstand position compression depth was 1.58 in +/- 0.20 in SD (4.01 cm +/- 0.51 cm), side straddle was 0.78 in +/- 0.44 in SD (1.98 cm +/- 1.12 cm), and waist straddle was 1.21 in +/- 0.47 in SD (3.07 cm +/- 1.19 cm) across rescuers with heights of 164-174 cm. Rates of compression were 98.3 +/- 6.3 SD, 100.0 +/- 3.0 SD, and 102.6 +/- 12.1 SD compressions per minute, respectively. Compression depth for one rescuer utilizing the Kendall CardioVent device in the handstand position was 1.48 in +/- 0.14 in SD (3.76 cm +/- 0.36 cm). Compression depth for two rescuers was 1.58 in +/- 0.20 in SD (4.01 cm +/- 0.51 cm) (p < 0.01). CONCLUSION: CPR in microgravity is most reliably performed in the handstand position and meets AHA guidelines for closed chest compression depth. One-rescuer CPR incorporating the Kendall CardioVent device appears promising in microgravity. CPR adjunct devices would positively impact resuscitative procedures like CPR by small crews with inherent manpower requirements.     

Medical qualification of a commercial spaceflight participant: not your average astronaut

BACKGROUND: Candidates for commercial spaceflight may be older than the typical astronaut and more likely to have medical problems that place them at risk during flight. Since the effects of microgravity on many medical conditions are unknown, physicians have little guidance when evaluating and certifying commercial spaceflight participants. This dynamic new era in space exploration may provide important data for evaluating medical conditions, creating appropriate medical standards, and optimizing treatment alternatives for long-duration spaceflight. CASE: A 57-yr-old spaceflight participant for an ISS mission presented with medical conditions that included moderately severe bullous emphysema, previous spontaneous pneumothorax with talc pleurodesis, a lung parenchymal mass, and ventricular and atrial ectopy. The medical evaluation required for certification was extensive and included medical studies and monitoring conducted in analogue spaceflight environments including altitude chambers, high altitude mixed-gas simulation, zero-G aircraft, and high-G centrifuge. To prevent recurrence of pneumothorax, we performed video-assisted thoracoscopic pleurodesis, and to assess lung masses, several percutaneous or direct biopsies. The candidate's 10-d mission was without incident. CONCLUSION: Non-career astronauts applying for commercial suborbital and orbital spaceflight will, at least in the near future, challenge aerospace physicians with unknowns regarding safety during training and flight, and highlight important ethical and risk-assessment problems. The information obtained from this new group of space travelers will provide important data for the evaluation and in-flight treatment of medical problems that space programs have not yet addressed systematically, and may improve the medical preparedness of exploration-class missions.     

Pilot study for predicting appropriate use of air medical helicopters. Part 1: Interfacility transports

Introduction: Appropriate use of rotor-wing aircraft is an important issue to the emergency transport industry. The purpose of this pilot study was to test criteria for their ability to accurately identify patients for whom interfacility helicopter transport is appropriate.Methods: Flight data collected from 219 flights included measures of physiological status, interventions, and need for timely care. Appropriate and inappropriate flights were compared using chi-square, Mann-Whitney U, and Wilcoxon matched-pairs signed rank tests. Logistic regression was used to evaluate how well information at critical decision points distinguishes between appropriate and inappropriate flights.Results: Statistical difference occurred between appropriate and inappropriate flights for the variables of preflight cardiac status, preflight interventions, preflight total score, flight crew vital signs, flight crew cardiac status, flight crew interventions, flight crew total score, need for surgical intervention, and need for complex critical care. No statistical difference existed between appropriate and inappropriate flights for the variables of preflight vital signs, preflight neurologic status, and flight crew neurologic status. Logistic regression models showed that coefficients for preflight total score, flight crew interventions, flight crew total score, need for surgical intervention, and need for complex critical care were significant. All other coefficients were not significant. Patients requiring emergent surgical intervention were more than four times likely to be considered an appropriate use of the aircraft, and patients requiring complex critical care were almost eight times more likely to be considered an appropriate use of the aircraft. Odds ratios for preflight and flight crew total scores revealed an increase in the likelihood of appropriateness as the total score values increased.Conclusion: Development of a gold standard to determine appropriate use of the aircraft and measurable criteria on which to base that decision is important. The instrument used in this pilot study now must be revised given statistical findings and input from the emergency transport industry.     

载人航天中微重力环境对认知功能的影响

目前在载人航天的研究中，对于在微重力条件下认知功能变化的研究还较少。本文综述了近年来这方面的一些进展。研究表明，在微重力条件下，空间定向、运动知觉出现障碍，早期物体识别受影响的程度也较大，肌肉运动和协调功能有所减弱。微重力条件对高级认知功能，如逻辑推理、短时记忆提取的速度和准确性等的影响较小，但是一些需要注意参与的认知任务(如跟踪任务、视觉选择反应)和长时记忆任务，在航天环境或模拟失重条件下会受到影响。     

Method for rehabilitation of the alcohol-addicted pilot in a commercial airline

Based upon data available from the National Council on Alcoholism and encouraged by the emerging concept of alcoholism as a disease responsive to the multidisciplinary approach to its management, a program to assist alcoholic employees was instituted in 1968 at the United Airlines Maintenance Operations Center in San Francisco. This program was developed through the tripartite efforts of management, union and the medical department. Using this basic model, a similar effort to assist flight crew members of our San Francisco pilot domicile emerged in 1970. The method is oriented to the three-fold process of identification, referral for treatment, and followup. The mechanism of identification includes an intervention process. Treatment is accomplished in a specialty hospital embracing the principles of Alcoholics Anonymous. The essential monthly followup is continued for 2 years. Twenty-five pilots in United's system have been returned to flight deck duties after treatment and recertification.