Life support in the intensive care unit: a qualitative investigation of technological purposes. Canadian Critical Care Trials Group.
BACKGROUND: The ability of many intensive care unit (ICU) technologies to prolong life has led to an outcomes-oriented approach to technology assessment, focusing on morbidity and mortality as clinically important end points. With advanced life support, however, the therapeutic goals sometimes shift from extending life to allowing life to end. The objective of this study was to understand the purposes for which advanced life support is withheld, provided, continued or withdrawn in the ICU. METHODS: In a 15-bed ICU in a university-affiliated hospital, the authors observed 25 rounds and 11 family meetings in which withdrawal or withholding of advanced life support was addressed. Semi-structured interviews were conducted with 7 intensivists, 5 consultants, 9 ICU nurses, the ICU nutritionist, the hospital ethicist and 3 pastoral services representatives, to discuss patients about whom life support decisions were made and to discuss life-support practices in general. Interview transcripts and field notes were analysed inductively to identify and corroborate emerging themes; data were coded following modified grounded theory techniques. Triangulation methods included corroboration among multiple sources of data, multidisciplinary team consensus, sharing of results with participants and theory triangulation. RESULTS: Although life-support technologies are traditionally deployed to treat morbidity and delay mortality in ICU patients, they are also used to orchestrate dying. Advanced life support can be withheld or withdrawn to help determine prognosis. The tempo of withdrawal influences the method and timing of death. Decisions to withhold, provide, continue or withdraw life support are socially negotiated to synchronize understanding and expectations among family members and clinicians. In discussions, one discrete life support technology is sometimes used as an archetype for the more general concept of technology. At other times, life-support technologies are discussed collectively to clarify the pursuit of appropriate goals of care. CONCLUSIONS: The orchestration of death involves process-oriented as well as outcome-oriented uses of technology. These uses should be considered in the assessment of life-support technologies and directives for their appropriate use in the ICU. (+info)
Impact of hetastarch on the intestinal microvascular barrier during ECLS.
The effects of hetastarch on microvascular fluid flux were determined in anesthetized dogs undergoing extracorporeal life support (ECLS) with a roller pump and membrane oxygenator. ECLS with a lactated Ringer priming solution resulted in a decrease in microvascular protein reflection coefficient and an increase in transvascular protein clearance. Use of a 6% hetastarch priming solution attenuated the decrease in microvascular protein reflection coefficient and blunted the increase in transvascular protein clearance. Ileal tissue water increased in the group treated with the lactated Ringer priming solution compared with the group treated with 6% hetastarch. The effective plasma-to-interstitial colloid osmotic pressure gradient was greater in the group treated with hetastarch than in the group treated with lactated Ringer solution. Hetastarch decreases the edema associated with ECLS. The reduction in edema is due to the maintenance of the plasma-to-interstitial colloid osmotic pressure gradient and the reduction in the microvascular permeability to protein. (+info)
Pediatricians and the Advanced Trauma Life Support (ATLS): time for reconsideration?
BACKGROUND: General pediatricians in Israel are actively involved in the initial evaluation, resuscitation and management of traumatized children. However, pediatric trauma care is not a part of pediatric specialty training in Israel, and the few Advanced Trauma Life Support courses per year are insufficient for most pediatricians working in accident and emergency care. OBJECTIVE: To examine the value of the course in relation to the limited resources available for such training. METHODS: A telephone survey of 115 pediatricians who had taken the course between 1990 and 1994 was conducted. The responding physicians (67%) were asked to complete a specially designed questionnaire on life-saving procedures that were taught in the course. In addition, they were asked to subjectively assess the practical utility of the course. RESULTS: Forty-three (56%) pediatricians reported that they routinely treated both adult and pediatric trauma cases. Of these, 81% performed 27 life-saving ATLS procedures. Pediatric trauma was treated by only 22 (28%), of whom 72.3% performed 18 life-saving ATLS procedures. These pediatricians ranked the courses as being "very high" to "high" in impact. CONCLUSIONS: These figures indicate that an ATLS course designed specifically for pediatricians can markedly improve pediatric trauma care. To ensure standard education and patient care, such a course should be developed and made a mandatory component of residency training. Further studies to examine the objective impact of the courses on pediatric trauma care should be carried out. (+info)
Liver support systems.
In recent years liver transplantation was shown to be the only clinically effective method of treating acute or chronic hepatic failure due to various causes. However, this ultimate therapeutic approach is limited by the growing disparity between organ donation and the number of patients on the waiting list. Factors such as high cost, morbidity, and the need for lifelong immunosuppression accelerated the research on alternative methods to support the failing liver. Recently, new technologies incorporating hepatocytes and extracorporeal circulation devices were introduced for liver support. This review presents current knowledge on liver support systems and their role in the treatment of acute liver failure. (+info)
Influence of changes in daylength and carbon dioxide on the growth of potato.
Potatoes (Solanum tuberosum L.) are highly productive in mid- to high-latitude areas where photoperiods change significantly throughout the growing season. To study the effects of changes in photoperiod on growth and tuber development of potato cv. Denali, plants were grown for 112 d with 400 micromol m-2 s-1 photosynthetic photon flux (PPF) under a 12-h photoperiod (short days, SD), a 24-h photoperiod (long days, LD), and combinations where plants were moved between the two photoperiods 28, 56, or 84 d after planting. Plants given LD throughout growth received the greatest total daily PPF and produced the greatest tuber yields. At similar levels of total PPF, plants given SD followed by LD yielded greater tuber dry mass (DM) than plants given LD followed by SD. Stem DM per plant, leaf DM, and total plant DM all increased with an increasing proportion of LD and increasing daily PPF, regardless of the daylength sequence. When studies were repeated, but at an enriched (1000 micromol mol-1) CO2 concentration, overall growth trends were similar, with high CO2 resulting in greater stem length, stem DM, leaf DM, and total plant DM; but high CO2 did not increase tuber DM. (+info)
Carp experiment in space microgravity--a visual-vestibular sensory conflict model.
In the 8-d flight mission of Spacelab-J (STS-47) conducted in 1992, behavior of the dorsal light response (DLR) and EEG activity of the cerebellum were intermittently examined for two carp, normal and otolith-removed. The latter carp had immobilization trouble caused by twisting of the EEG cable on day 2 inflight. The problem continued for the remainder of the experiment. Analyses made on the normal carp provided additional evidence in fish for sensory-motor disorder and readjustment during early phase of microgravity, thus supporting the sensory conflict hypothesis for space motion sickness. In the present report, why and how this space experiment was conducted were reviewed with a brief summary of the results. (+info)
Very high CO2 reduces photosynthesis, dark respiration and yield in wheat.
Although terrestrial CO2 concentrations, [CO2] are not expected to reach 1000 micromoles mol-1 for many decades, CO2 levels in closed systems such as growth chambers and glasshouses, can easily exceed this concentration. CO2 levels in life support systems in space can exceed 10000 micromoles mol-1 (1%). Here we studied the effect of six CO2 concentrations, from ambient up to 10000 micromoles mol-1, on seed yield, growth and gas exchange of two wheat cultivars (USU-Apogee and Veery-l0). Elevating [CO2] from 350 to 1000 micromoles mol-1 increased seed yield (by 33%), vegetative biomass (by 25%) and number of heads m-2 (by 34%) of wheat plants. Elevation of [CO2] from 1000 to 10000 micromoles mol-1 decreased seed yield (by 37%), harvest index (by 14%), mass per seed (by 9%) and number of seeds per head (by 29%). This very high [CO2] had a negligible, non-significant effect on vegetative biomass, number of heads m-2 and seed mass per head. A sharp decrease in seed yield, harvest index and seeds per head occurred by elevating [CO2] from 1000 to 2600 micromoles mol-1. Further elevation of [CO2] from 2600 to 10000 micromoles mol-1 caused a further but smaller decrease. The effect of CO2 on both wheat cultivars was similar for all growth parameters. Similarly there were no differences in the response to high [CO2] between wheat grown hydroponically in growth chambers under fluorescent lights and those grown in soilless media in a glasshouse under sunlight and high pressure sodium lamps. There was no correlation between high [CO2] and ethylene production by flag leaves or by wheat heads. Therefore, the reduction in seed set in wheat plants is not mediated by ethylene. The photosynthetic rate of whole wheat plants was 8% lower and dark respiration of the wheat heads 25% lower when exposed to 2600 micromoles mol-1 CO2 compared to ambient [CO2]. It is concluded that the reduction in the seed set can be mainly explained by the reduction in the dark respiration in wheat heads, when most of the respiration is functional and is needed for seed development. (+info)
Dive Europa: a search-for-life initiative.
Liquid water, underwater volcanoes and possibly life forms have been suggested to be present beneath the estimated 10 km-thick ice shell of Europa the Jovian satellite J2. Europa's possible ocean is estimated to be 100-200km deep. Despite the great depth of the Europa's ocean, hydrostatic pressure at the seafloor would be 130-260 MPa, corresponding to 13-26 km depth of a theoretical Earth's ocean. The hydrostatic pressure is not beyond the edge of existing deep-sea technology. Here we propose exploration of Europa's deep-sea by the use of current technologies, taking a symbolic example of a deep submergence vehicle Shinkai 6500 which dives to a depth of 6.5 km deep (50 km depth of Europa's ocean). Shinkai 6500 is embarkable in the payload bay of the Space Shuttles in terms of size and weight for the transportation to a Low Earth Orbit (LEO). Secondary boost is needed for interplanetary flight from the LEO. On-orbit assembly of the secondary booster is a technological challenge. The International Space Station (ISS) and ISS-related technologies will facilitate the secondary boost. Also, ice shell drilling is a challenge and is needed before the dive into Europa's ocean. These challenges should be overcome during a certain leading time for matured experience in the ISS operation. (+info)