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.     

Effects of vitamin D3 metabolites on bone cell calcium transport

Summary The vitamin D₃ metabolite, 25-hydroxycholecalciferol, at concentrations of 0.01 to 10.0 g/ml, decreased calcium uptake by isolated bone cells. The effect occurred within 1 min after the simultaneous addition of metabolite and⁴⁵Ca. Lactic acid and ATP production by the cells was not affected. 24(R), 25-dihydroxycholecalciferol produced a similar decrease in calcium uptake. Vitamin D₃ had no effect at concentrations from 0.01 to 10.0 g/ml. No effect of 1,25-dihydroxycholecalciferol on calcium uptake was observed with concentrations from 0.1 to 100 ng/ml and various preincubation periods extending to 2 h. None of the agents had any effect on calcium efflux. The effects of 25-hydroxycholecalciferol and 24(R), 25-dihydroxycholecalciferol on calcium uptake were not seen in isolated fetal rat skin cell preparations.     

Pharmacokinetics of methotrexate in leukemia cells: Effect of dose and mode of injection

A lumped compartmental model has been derived to predict methotrexate concentration as a function of time for L1210 cells in BD2F ₁ female mice at doses ranging from 3 mg/kg to 400 mg/kg. Using standard methods of parameter estimation as well as experimental determinations, an integrated approach was derived to account for the differences between the subcutaneous (s.c.) and intraperitoneal (i.p.) modes of injection. It was found that a single generalized forcing function can be used to fit plasma concentration after s.c. injection for all doses. Adequate fits (average error<20% while the standard deviation of experimental determinations was±22%) of L1210 cell data after s.c. injection were obtained. The best results were for a maximum facilitated influx constant V_max of 0.424 g/min/ml, a Michaelis influx constant K_m of 1,42 g/ml, and a first-order efflux constant of 0.047 min^–1.The model simulations were not sensitive to V_max, K_m,and so long as the ratio V_max/was approximately 9g/ml. The values of V _max ,K _m ,and which were obtained from our analysis of the in vivodata can be explained on the basis of previously performed in vitroexperiments. The parameters obtained from modeling the s.c. data were then applied for i.p. injection data. The resulting fits were adequate (average error<20% while the standard deviation of experimental determinations was±22%). A single generalized forcing function for drug concentration in the peritoneal cavity after i.p. injection for all doses was derived. The application of these results enables the prediction of methotrexate concentration in neoplastic cells at other doses after either s.c. or i.p. injection.     

Noradrenaline transport by rat heart sympathetic nerves: A re-examination of the role of sodium ions

Summary The effect of sodium ion on ³H-(–)-noradrenaline (0.0875 to 0.5 M) transport by rat heart atrial hemi-appendages incubated in vitro has been studied, and the following observations made: a) When sodium was omitted (choline and lithium substitution) there was no evidence for active noradrenaline transport, and only a component that did not show saturation kinetics up to 1 M noradrenaline, remained. b) Omission of sodium or addition of 4×10^–5 M desipramine inhibited noradrenaline transport to exactly the same extent, and their effects were not additive. Alprenolol did not reduce this sodium-independent transport, but tropolone lowered it somewhat. c) No evidence for corticosterone-sensitive noradrenaline transport (uptake-2) was found in this preparation at the low amine concentrations used. d) In control medium, the kinetic parameters of transport were: K _m: 0.59 ± 0.063 M and V _max: 2.44 ± 0.43 (pmoles/mg protein/min). With 26 mM sodium and the rest substituted by choline, K _m:2.26 ± 0.70 M (P0.001) and V _max: 2.74 ± 0.43 (pmoles/mg protein/min) (not significant). Also with 26 mM sodium, but with sucrose substitution, K _m: 0.76 ± 0.13 M (N.S.) and V _max: 1.06 ± 0.13 (pmol/mg/min) (P<0.05). Such results indicate that sodium only modifies the affinity of the transport system for noradrenaline, without changing V _max, and that changes in the latter are only a consequence of a reduction of the ionic strength. e) When noradrenaline transport was studied at different concentrations of external sodium, at constant ionic strength and with precautions to minimize the noradrenaline-releasing effect of low sodium, it was found that the data could be best represented by two hyperbolas placed in series. This suggests that the noradrenaline carrier has two sites for sodium, that do not interact with each other. When the same experiments were repeated in the absence of chloride, it was found that the noradrenaline transport system had lost virtually all its affinity for sodium. f) The effect of prolonged tissue incubation in the absence of sodium was found to produce a relatively small inactivation of noradrenaline transport. Such phenomenon was enhanced by raising the calcium concentration to 2 mM.     

Thymidine transport in hepatocytes

Thymidine transport and phosphorylation were investigated in isolated rat hepatocytes and AS 30 D hepatoma cells. In contrast to hepatoma cells, hepatocytes exhibited a minimum of thymidine phosphorylation due to a 100-fold smaller thymidine kinase activity. In hepatocytes thymidine is transported by two transport systems: a specific concentrative high affinity system and an unspecific non-concentrative low affinity system. In hepatoma cells only the low affinity system could be detected. A single dose of 20 or 50 mg diethylnitrosamine/kg body weight induced in hepatocytes a remarkable increase of thymidine kinase activity and a decrease of the transport by the high affinity system. Thymidine transport and phosphorylation by hepatocytes are considered to be sensitive markers for early recognition of toxin-induced liver regeneration.

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Zusammenfassung Thymidintransport und -phosphorylierung wurden in isolierten Rattenhepatozyten und AS 30 D-Hepatomzellen untersucht. Hepatozyten wiesen im Gegensatz zu Hepatomzellen aufgrund einer 100fach niedrigeren Thymidinkinaseaktivität eine äußerst niedrige Thymidinphosphorylierungsrate auf. In Hepatozyten wurde Thymidin durch zwei Transportsysteme aufgenommen: ein spezifisches, konzentratives high affinity System und ein unspezifisches, nichtkonzentratives low affinity System. In ATP-freien Hepatomzellen konnte nur das low affinity System nachgewiesen werden. Eine einmalige Dosis von 20 bzw. 50 mg Diäthylnitrosamin/kg Körpergewicht bewirkte in Hepatozyten einen Anstieg der Thymidinkinaseaktivität und eine Verminderung des Thymidintransports über das high affinity System. Thymidintransport und -phosphorylierung in Hepatozyten erwiesen sich als sensitives System zur frühen Erkennung beginnender Leberregeneration nach toxischer Vorschädigung.

     

Carrier mediated transport of choline in rat lens

Choline accumulation was studied in rat lenses incubated in TC-199 medium containing radiolabeled choline. Choline entered the lens and was rapidly phosphorylated. Phosphorylcholine did not readily escape the lens and continued to accumulate throughout 24 hr of incubation. Accumulation of choline displayed saturation kinetics and this saturability appeared to be a property of transport rather than a reflection of the properties of choline kinase. Countertransport of labeled choline from lenses preloaded with radiolabeled choline indicates that choline transport in rat lens is carrier mediated. The existence of a choline carrier would also be consistent with the kinetic data. Ethanolamine competed for the choline carrier, however a component of ethanolamine uptake was non-saturable at concentrations of ethanolamine or choline up to 5 mm. Choline and ethanolamine appeared to be phosphorylated by separate kinases in lens.     

Analysis of orthograde fast axonal transport and nonaxonal transport along the optic pathway of albino rabbits during increased and decreased intraocular pressure

Orthograde fast axonal and nonaxonal transport through the optic disc was studied quantitatively and autoradiographically in albino rabbits during elevated (30 or 50 mmHg), normal (13–15 mmHg) and decreased (0–4 mmHg) intraocular pressure (IOP). In cases of intraocular hypertension up to 50 mmHg, autoradiographic findings of a disturbed orthograde fast axonal transport were seen in the optic disc within 3 hr. The blockage was relatively mild and uniform, and was distributed adjacent to the extension line of sclera. Despite this histological evidence of blockage, a quantitative analysis showed no statistically significant decrease in axonally transferred radioactivity within 3 hr. Decrease in the transferred material was evident at 6 hr, and the extent of decrease was mild (ca. 20% at the most prominent portion). In cases of moderate intraocular hypertension (30 mmHg) for 6 hr, a quantitative analysis showed no decrease in axonal transport. After 3–6 hr of intraocular hypotension (0–4 mmHg), papilledema did not develop and autoradiographically there was no accumulatjon of axonal components. Axonally transferred material remained quantitatively at the same level as in the control animals. Nonaxonal transport along the optic nerve was doubly enhanced in cases of intraocular hypertension up to 50 mmHg, and was reduced to one thrid at level of 0–4 mmHg. Filtration of intraocular fluid through the optic disc appears to be the largest component of the nonoxonal transport.     

Competitive inhibition of the uptake of demethylphalloin by cholic acid in isolated hepatocytes

Summary Cholic acid inhibits the uptake of demethylphalloin (DMP), in a competitive manner. The bile acid increases the Michaelis constant but not V _max of the inward transport. The inhibition constant K _i for cholate was found to be 8 M. Cholate competes for the transport system but not for intracellular binding of phallotoxins. Various experimental data presented in this paper exclude an accumulation of phallotoxins in hepatocytes by intracellular binding only.Preincubation of hepatocytes with small concentrations of either (³H)-demethylphalloin or (¹⁴C)-cholate and subsequent treatment with high concentrations of the nonlabelled compounds reduces the intracellular concentration of both radioactive substrates. In accordance with earlier findings the above results suggest a common component needed for the transport of both phallotoxins and cholic acid.This work was supported by the Deutsche Forschungsgemeinschaft     

The effects of capsaicin upon electrogenic ion transport in rat descending colon

Summary Preparations of rat descending colon mucosa have been used to record changes in short circuit current (SCC) under voltage clamp conditions. When added to the basolateral compartment capsaicin (8-methyl-N-vanillyl-6-nonenamide, 0.1-3 M) caused an initial transient increase in SCC, followed by a more prolonged reduction in SCC, that lasted for 20–30 min.Repeated applications of 3 M capsaicin caused desensitisation of the initial secretory response. The antisecretory effects (i. e. reduction in SCC from the original baseline) remained, although they were significantly reduced. In some preparations described as non-responders, 3 M capsaicin did not elicit a secretory response. No desensitisation of the remaining antisecretory responses was observed in these tissues; in fact these reductions in SCC were consistently larger than those from tissues which responded with a secretory response.Tetrodotoxin (100 nM), hexamethonium (10 M), and yohimbine (50 M) had no significant effect upon either secretory or antisecretory responses. Ruthenium red (10 M) abolished the secretory response to 3 M capsaicin, but had no effect upon the antisecretory responses. Pretreatment of the tissues with 1 M substance P(SP) resulted in significant desensitisation to the peptide and abolished the secretory response to 3 M capsaicin. The antisecretory responses remained, and were significantly larger compared with responses from control tissues. Send offprint requests to H. M. Cox at present address