Advanced Life Support Systems Research Articles

Recovery of resources for advanced life support space applications: effect of retention time on biodegradation of two crop residues in a fed-batch, continuous stirred tank reactor

Bioreactor retention time is a key process variable that will influence costs that are relevant to long distance space travel or long duration space habitation. However, little is known about the effects of this parameter on the microbiological treatment options that are being proposed for Advanced Life Support (ALS) systems. Two bioreactor studies were designed to examine this variable. In the first one, six retention times – ranging from 1.3 to 21.3 days – were run in duplicate, 8 l working-volume continuous stirred tank reactors (CSTR) that were fed ALS wheat residues. Ash-free dry weight loss, carbon mineralization, soluble TOC reduction, changes in fiber content (cellulose, hemicellulose, and lignin), bacterial numbers, and mineral recoveries were monitored. At short retention times – 1.33 days – biodegradation was poor (total: 16–20%, cellulose – 12%, hemicellulose – 28%) but soluble TOC was decreased by 75–80% and recovery of major crop inorganic nutrients was adequate, except for phosphorus. A high proportion of the total bacteria (ca. 83%) was actively respiring. At the longest retention time tested, 21.3 days, biodegradation was good (total: 55–60%, cellulose – ca. 70%, hemicellulose – ca. 55%) and soluble TOC was decreased by 80%. Recovery of major nutrients, except phosphorus, remained adequate. A very low proportion of total bacteria was actively respiring (ca. 16%). The second bioreactor study used potato residue to determine if even shorter retention times could be used (range 0.25–2.0 days). Although overall biodegradation deteriorated, the degradation of soluble TOC continued to be ca. 75%. We conclude that if the goal of ALS bioprocessing is maximal degradation of crop residues, including cellulose, then retention times of 10 days or longer will be needed. If the goal is to provide inorganic nutrients with the smallest volume/weight bioreactor possible, then a retention time of 1 day (or less) is sufficient.

Sodium chloride removal from urine via a six-compartment ED cell for use in Advanced Life Support Systems (Part 2: Limiting current density behavior)

A six-compartment electrodialysis cell with univalent ion selective membranes was used to remove sodium chloride from human urine for Advanced Life Support applications that will be used in long-term space travel. To study the feasibility of this system, the first variable under study was the limiting current density ( i lim). Working at current densities lower than i lim allows obtaining better efficiency of sodium chloride removal and extends the membrane's useful life. The i lim data were obtained at four fluid velocities ranging from 0.015 to 0.083 m/s and four urine dilution ratios ranging from 3,200 to 12,800 ppm, based on chloride salts concentration. The i lim was found to be a power function of fluid velocity and Cl − salts concentration correlated by the model i lim = 4105 U 0.9 C. An average current efficiency of 50% based on Na + ion removal indicated that half of the applied current was used in sodium chloride transport. Higher and more stable current efficiencies than those of continuous flow mode of operation were found for batch recirculation experiments.

Sodium chloride removal from urine via a six-compartment ED cell for use in Advanced Life Support Systems (Part 1: salt removal as a function of applied voltage and fluid velocity)

A six-compartment electrodialysis cell with univalent ion selective membranes was studied to remove sodium chloride from human urine. Current-voltage behavior data were obtained at four fluid velocities ranging from 0.015 to 0.083 m/s, and four urine dilution ratios ranging from 3,200 to 12,800 ppm, based on chloride salts concentration. Ion chromatography revealed that the highest sodium chloride percentage for continuous once-through mode of operation was of 91.0% achieved at the most diluted solution ( U = 0.039 m/s and i = 57 A/m 2). For batch recirculation, the operational voltages were 5.0, 7.5 and 9.0 V and a constant velocity of 0.083 m/s was used. Under this mode of operation the highest removal, 98.5%, was achieved at a potential of 9.0 V.

Model-based predictive control for biomass production in advanced life support

A model-based predictive control (MBPC) algorithm for crop production in a biomass production component of an Advanced Life Support System (ALSS) is introduced. The MBPC adjusts light intensity, air temperature, and atmospheric carbon dioxide concentration setpoints so that crop growth (total and yield biomass) follows pre-determined production schedules. Mathematical models developed for wheat, soybean, and white potato using multivariate polynomial regression (MPR) are used as the feed-forward models in the control. The control algorithm is evaluated for its ability to compensate for simulated environmental disturbances and sensitivity to modeling and measurement errors. A 24-hour time increment is utilized

Automation for Biomass Production within Advanced Life Support Systems

Advanced life support systems for manned long-duration space missions include four major subsystems: crew, biomass production, food processing and nutrition, and waste processing and resource recovery. Crew time requirements are a concern, especially in the potentially labor intensive operation of the biomass production subsystem. Different types of automation (including mechanization and robotics) are needed in order to reduce crew time. Automation is an important aspect of advanced biomass production systems within controlled environment life support systems. A biomass production subsystem model was developed to investigate the effects of different crop and automation scenarios on crew time requirements.

Control of Crop Growth in Advanced Life Support Systems

An elementary method for controlling crop growth in Advanced Life Support Systems is presented. Two models for crop growth are considered, one developed by the agricultural industry and used by the Ames Research Center, and a mechanistic model. termed the Energy Cascade model. The controller is applied to both models using wheat as the crop. A variety of circumstances are considered, such as model errors, measurement errors, and the incapability of applying the desired control input. It is shown that the proposed approach is a potentially viable way of controlling crop growth.

Scheduling and Control of Crop Production for Advanced Life Support

Advanced life support systems will support human lives during space journeys. Plants will provide food, consume CO2, produce O2, and clean water within the enclosed systems. Computer models were developed for the purpose of analyzing effects of crop production schemes on food supply and resource requirements and for controlling plant growth and development. An object-oriented approach was used to develop a top-level model for crop production scheme analysis. Another approach developed controlled environment crop growth and development models by modifying open field crop models for formulating model-based control algorithms. This paper presents an overview of these two different approaches.

Quantification and characterization of volatiles evolved during extrusion of rice and soy flours.

NASA-Johnson Space Center is designing and building a habitat (Bioregenerative Planetary Life Support Systems Test Complex, BIO-Plex) intended for evaluating advanced life support systems developed for long-duration missions to the Moon or Mars where all consumables will be recycled and reused. A food system based on raw products obtained from higher plants (such as soybeans, rice, and wheat) may be a central feature of a biologically based Advanced Life Support System. To convert raw crops to edible ingredients or food items, multipurpose processing equipment such as an extruder is ideal. Volatile compounds evolved during the manufacturing of these food products may accumulate and reach toxic levels. Additionally, off-odors often dissipated in open-air environments without consequence may cause significant discomfort in the BIO-Plex. Rice and defatted soy flours were adjusted to 16% moisture, and triplicate samples were extruded using a tabletop single-screw extruder. The extrudate was collected in specially designed Tedlar bags from which air samples could be extracted. The samples were analyzed by GC-MS with special emphasis on compounds with Spacecraft Maximum Allowable Concentrations (SMACs). Results showed a combination of alcohols, aldehydes, ketones, and carbonyl compounds in the different flours. Each compound and its SMAC value, as well as its impact on the air revitalization system, was discussed.

Long term outcome after out-of-hospital cardiac arrest with physician staffed emergency medical services: the Utstein style applied to a midsized urban/suburban area

OBJECTIVETo test the effect of a physician staffed advanced cardiac life support (ALS) system on patient outcome following out-of-hospital cardiac arrest.DESIGNObservational study.SETTINGTwo tier basic life support (BLS) and physician staffed...

Transfer from Long to Short Photoperiods Affects Production Efficiency of Day-neutral Rice

The day-neutral, semidwarf rice (Oryza sativa L.) cultivar Ai-Nan-Tsao was grown in a greenhouse under summer conditions using high-pressure sodium lamps to extend the natural photoperiod. After allowing 2 weeks for germination, stand establishment, and thinning to a consistent planting density of 212 plants/m2, stands were maintained under continuous lighting for 35 or 49 days before shifting to 8- or 12-h photoperiods until harvest 76 days after planting. Non-shifted control treatments consisting of 8-, 12-, or 24-h photoperiods also were maintained throughout production. Tiller number increased as duration of exposure to continuous light increased before shifting to shorter photoperiods. However, shoot harvest index and yield efficiency rate were lower for all plants receiving continuous light than for those under the 8- or 12-h photoperiods. Stands receiving 12-h photoperiods throughout production had the highest grain yield per plant and equaled the 8-h-photoperiod control plants for the lowest tiller number per plant. As long as stands were exposed to continuous light, tiller formation continued. Shifting to shorter photoperiods late in the cropping cycle resulted in newly formed tillers that were either sterile or unable to mature grain before harvest. Late-forming tillers also suppressed yield of grain in early-forming tillers, presumably by competing for photosynthate or for remobilized assimilate during senescence. Stands receiving 12-h photoperiods throughout production not only produced the highest grain yield at harvest but had the highest shoot harvest index, which is important for resource-recovery strategies in advanced life-support systems proposed for space.

The Efficacy of Advanced Life Support: A Review of the Literature

Jurisdictions throughout the United States and some other parts of the world have invested substantial time and resources into creating and sustaining a prehospital advanced life support (ALS) system without knowing whether the efficacy of ALS-level care had been validated scientifically. In recent years, it has become fashionable for speakers before large audiences to declare that there is no scientific evidence for the clinical effectiveness of ALS-level care in the out-of-hospital setting. This study was undertaken to evaluate the evidence that pertains to the efficacy of ALS-level care in the current scientific literature. An extensive review of the available literature was accomplished using computerized and manual means to identify all applicable articles from 1966 to October, 1995. Selected articles were read, abstracted, analyzed, and compiled. Each article also was categorized as presenting evidence supporting or refuting the clinical efficacy of ALS-level care, and a list was constructed that pointed to where the preponderance of the evidence lies. Research in this field differs widely in terms of methodological sophistication. Of the 51 articles reviewed, eight concluded that ALS-level care is not any more effective than is basic life support, seven concluded that it is effective in some applications but not for others, and the remainder demonstrated effectiveness. The strongest support for ALS-level care was in the area of responses to victims of cardiac arrest, whereas somewhat more divergent findings related to trauma or non condition-specific studies. While not unanimous, the predominant finding of recent research into the clinical effectiveness of advanced life support demonstrates improved effectiveness over basic life support for patients with certain pathologies. More outcomes-based research is needed.

Nutritional Quality of Sweetpotato Greens from Greenhouse Plants

Sweetpotato (Ipomoea batatas(L.) Lam.) is a candidate root crop for production in the Advanced Life Support System (ALSS) program of the National Aeronautic and Space Administration (NASA). To increase the edible plant portion, the use of young leaves and petioles from sweetpotato grown by the nutrient film technique (NFT) as a green or leafy vegetable for ALSS is promoted. This study was conducted to determine the nutritional quality of sweetpotato greens from plants grown by NFT. Nutrient concentrations in greens from the same cultivars (Georgia Jet, Jewel, and TU-82-155) grown in greenhouse beds were also obtained for comparison. Raw greens from hydroponic and bed plants were analyzed for dry matter, protein, ash, total dietary fiber, fat, minerals (Ca, Fe, K, Na, Mg, Zn), vitamins (carotene, ascorbic acid, thiamine), oxalic and tannic acids, and chymotrypsin and trypsin inhibitors. Differences in the nutrient and antinutrient concentrations were observed in the three cultivars due to variety and production method.

Effectiveness of Emergency Medical Services for Victims of Out-of-Hospital Cardiac Arrest: A Metaanalysis

To determine the relative effectiveness of differences in response time interval, proportion of bystander CPR, and type and tier of emergency medical services (EMS) system on survival after out of hospital cardiac arrest. We performed a comprehensive literature search, excluding EMS systems other than those of interest (systems of interest were those comprising one tier with providers of basic life support [BLS] or advanced life support [ALS] and those comprising two tiers with providers of BLS or BLS-defibrillation followed by ALS), patient population of fewer than 100 cardiac arrests, studies in which we could not determine the total number of arrests of presumed cardiac origin, and studies lacking data on survival to hospital discharge. Metaanalysis using generalized linear model with dispersion estimation for random effects was then performed. Increased survival to hospital discharge was significantly associated with tier (P < .01), response time interval (P < .01), and bystander CPR (P = .04). A significant interaction was detected between response time interval and bystander CPR (P = .02). For the studies analyzed, survival was 5.2% in a one-tier EMS system or 10.5% in a two-tier EMS system. A 1-minute decrease in mean response time interval was associated with absolute increases in survival rates of .4% and .7% in a one-tier and two-tier EMS systems, respectively. Increased survival to hospital discharge may be associated with decreased response time interval and with the use of a two-tier EMS system as opposed to a one-tier system. The data available for this analysis were suboptimal. Policymakers need more methodologically rigorous research to have more reliable and valid estimates of the effectiveness of different EMS systems.

Mission simulation as an approach to develop requirements for automation in advanced life support systems

This paper examines mission simulation as an approach to develop requirements for automation and robotics for Advanced Life Support Systems (ALSS). The focus is on requirements and applications for command and control, control and monitoring, situation assessment and response, diagnosis and recovery, adaptive planning and scheduling, and other automation applications in addition to mechanized equipment and robotics applications to reduce the excessive human labor requirements to operate and maintain an ALSS. Based on principles of systems engineering, an approach is proposed to assess requirements for automation and robotics using mission simulation tools. First, the story of a simulated mission is defined in terms of processes with attendant types of resources needed, including options for use of automation and robotic systems. Next, systems dynamics models are used in simulation to reveal the implications for selected resource allocation schemes in terms of resources required to complete operational tasks. The simulations not only help establish ALSS design criteria, but also may offer guidance to ALSS research efforts by identifying gaps in knowledge about procedures and/or biophysical processes. Simulations of a planned one-year mission with 4 crewmembers in a Human Rated Test Facility are presented as an approach to evaluation of mission feasibility and definition of automation and robotics requirements.

NASA's advanced life support systems human-rated test facility

Future NASA missions to explore the solar system will be long-duration missions, requiring human life support systems which must operate with very high reliability over long periods of time. Such systems must be highly regenerative, requiring minimum resupply, to enable the crews to be largely self-sufficient. These regenerative life support systems will use a combination of higher plants, microorganisms, and physicochemical processes to recycle air and water, produce food, and process wastes. A key step in the development of these systems is establishment of a human-rated test facility specifically tailored to evaluation of closed, regenerative life supports systems — one in which long-duration, large-scale testing involving human test crews can be performed. Construction of such a facility, the Advanced Life Support Program's (ALS) Human-Rated Test Facility (HRTF), has begun at NASA's Johnson Space Center, and definition of systems and development of initial outfitting concepts for the facility are underway. This paper will provide an overview of the HRTF project plan, an explanation of baseline configurations, and descriptive illustrations of facility outfitting concepts.

Johnson Space Center's Regenerative Life Support Systems Test Bed

The Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center is an atmospherically closed, controlled environment facility for human testing of regenerative life support systems using higher plants in conjunction with physicochemical life support systems. The facility supports NASA's Advanced Life Support (ALS) Program. The facility is comprised of two large scale plant growth chambers, each with approximately 11 m 2 growing area. The root zone in each chamber is configurable for hydroponic or solid media plant culture systems. One of the two chambers, the Variable Pressure Growth Chamber (VPGC), is capable of operating at lower atmospheric pressures to evaluate a range of environments that may be used in a planetary surface habitat; the other chamber, the Ambient Pressure Growth Chamber (APGC) operates at ambient atmospheric pressure. The air lock of the VPGC is currently being outfitted for short duration (1 to 15 day) human habitation at ambient pressures. Testing with and without human subjects will focus on 1) integration of biological and physicochemical air and water revitalization systems; 2) effect of atmospheric pressure on system performance; 3) planetary resource utilization for ALS systems, in which solid substrates (simulated planetary soils or manufactured soils) are used in selected crop growth studies; 4) environmental microbiology and toxicology; 5) monitoring and control strategies; and 6) plant growth systems design. Included are descriptions of the overall design of the test facility, including discussions of the atmospheric conditioning, thermal control, lighting, and nutrient delivery systems.

Factors influencing successful intubation in the prehospital setting.

To explore the determinants influencing oral/nasal endotracheal intubation (OETI/NETI) and determine which cognitive, therapeutic, and technical interventions may assist prehospital airway management. Prospective review of run reports and structured interviews of paramedics involved in OETI/NETI attempts were conducted in a high-volume, inner-city, advanced life support (ALS) system during an eight-month period (July 1991 to February 1992). Data were abstracted from run reports, and paramedics were asked in structured interviews to describe difficulties in OETI/NETI attempts. Of 236 patients studied, 88% (208) were intubated successfully. Success/failure rate was not related statistically to patients' ages (p = 0.78), medical or trauma complaint (89% vs 85%, p = 0.35), oral versus nasal route (88% vs 85%, p = 0.38), care time (scene+transport times: success, 18 minutes; failure, 20 minutes, p = 0.30), paramedic seniority (p = 0.13), or number of attempts per paramedic (p > 0.05). Increased level of consciousness (LOC) was associated with decreased success rate (p = 0.04). Paramedics reported difficulties in endotracheal intubation (ETI) attempts in 110 (46.6%) of patients. Factors reported to increase ETI difficulty were: 1) technical problems (35.6%); 2) mechanical problems (15.6%); and 3) combative patients (12.7%). Oral endotracheal intubation and NETI success rates identified in this study are similar to those described in the literature, although innovative strategies could be used to facilitate prehospital airway management. Many of the factors found to increase ETI difficulty could be ameliorated by the administration of paralytic agents, that is, for combative patients. Focused training in cadaver and animal labs coupled with recurrence training in the operating suites should be used on a regular basis to decrease difficulties in visualization. Interventions directed at alleviating mechanical difficulties that should be explored include new-to-the-field techniques, such as retrograde intubation, fiber-optic technology, and surgical tracheal access.

Association of out-of-hospital criteria with need for hospital admission.

To validate high-risk historical and physiologic out-of-hospital criteria as predictors of the need for hospitalization following ED evaluation. Consecutive patients entered into the Suffolk County advanced life support system were enrolled. Previously proposed historical and physiologic "high-risk" criteria for hospitalization were prospectively collected. Criteria were associated with the need for hospital admission following ED evaluation. 1,238 patients were enrolled; 391 were released from an ED after transport. Most patients (843/1,238; 68%) were admitted to a hospital; and four died in the ED. Factors associated with an increased likelihood of admission or death among the transported patients were: bradycardia (90% admitted, p < 0.02); hypotension (80%, p < 0.03); hypertension (89%, p < 0.03); and age > 55 years (81%, p < 0.0001). Unresponsiveness and other abnormal vital signs were not associated with admission on univariate analysis. Logistic regression analysis identified two other factors associated with admission or death: tachycardia (72% admitted, p < 0.01) and head injury (78% admitted, p < 0.001). Abnormal pulse or blood pressure, head injury, and age > 55 years are associated with patients' requiring hospital admission after accessing the emergency medical services system. These criteria may aid the design of out-of-hospital refusal-of-care policies.

Study of multiple rotor-wing flight programs on emergency medical services

Introduction: Improvements in prehospital care, designation of trauma centers and expeditious transport have significantly reduced trauma deaths. In 1985 Pennsylvania formally introduced trauma-system implementation, including the integration of regional prehospital trauma guidelines. The purpose of this study is to examine the similarities and dissimilarities of advanced life support (ALS) trauma operations in eastern Pennsylvania and southern New Jersey, and the impact and integration of multiple flight programs on regional ALS systems. Setting: Ground ALS (GALS) operations within Pennsylvania and New Jersey, and air medical operations in Pennsylvania. Methods: Site visits and telephone interviews were used to characterize demographic, operational and clinical practice characteristics, including those flights where GALS was on location. Descriptive statistics were used to compare the various programs. Results: Airway management differed greatly among the respondents. For example, of five air medical services, one did not carry paralytic agents, and one performed oral intubations only after the use of such agents. None of the GALS services used such agents. Procedures that required direct physician orders varied among the flight programs and the GALS services. Trauma triage guidelines following the American College of Surgeons recommendations were modified by all GALS services. Conclusions: Wide variation in the scope of practice exists among air medical services and GALS services within New Jersey and Pennsylvania.

Sudden cardiac death. How to reduce the number of victims?

Considerable effort and large sums of money have been spent on constructing a risk profile for sudden death in the myocardial infarction survivor at the time of discharge from hospital. However, these patients are only a minority among those dying suddenly outside hospital. The majority of sudden death victims cannot be identified before the event and their survival depends on the presence of people knowing how to perform basic life support and the rapid availability of advance life support systems. This suggests that measures other than the assignment of expensive therapy to a small segment of the population might be more cost effective and numerically more successful.