Biomedical subjects

M Helm

Publications and source records attributed to M Helm.

At least 19 recordsLinked to original sources

PubMed2007

[Intraosseous puncture in preclinical emergency medicine. Ten years experience in air rescue service].

INTRODUCTION: The intraosseous puncture (IO) is a fast and safe alternative to the puncture of peripheral veins in emergency situations in children < or =6 years of age. The purpose of this paper is to summarize 10 years of experience on the prehospital use of the IO method by the Helicopter Emergency Medical Service (HEMS) "Christoph 22", Ulm. MATERIALS AND METHODS: This was a retrospective study from 1 January 1996 to 31 December 2005. RESULTS: Out of a total of 9,549 missions, the proportion of children was 11.1%. In 27 children (4.2% of the children < or =6 years of age) an IO puncture was performed. Patients of the IO group were younger (1.0 vs. 3.7 years of age; p<0.001) and showed a higher degree of injury severity (NACA 6 vs. 4; p<0.001) compared to the total children group. In all children of the IO group (100%), the intraosseous puncture was the method of first choice to obtain access to the vascular system by the HEMS team. In 96.4% of these cases (26/27), the first IO puncture attempt was successful - in one child, a second puncture attempt was necessary. A standardized puncture technique was performed using the proximal tibia. The time required for successful placement of the IO infusion line was 60 s or less in all cases. In 37% of the cases (10/27) the IO infusion line was used for induction of general anaesthesia; dosage and onset of administered drugs were described as being equivalent to a peripheral infusion line. In all cases, the IO needle was replaced in-hospital within 2 h by a central or peripheral iv line. No complications were observed. CONCLUSIONS: The IO infusion technique is a simple, fast and safe alternative method for emergency access to the vascular system in children < or =6 years of age in the prehospital setting.

Aircraft↗

PubMed2005

Factors influencing emergency intubation in the pre-hospital setting--a multicentre study in the German Helicopter Emergency Medical Service.

BACKGROUND: Definitive airway control by endotracheal intubation (ETI) is standard of care in pre-hospital airway management. However, there are specific factors that may influence and complicate ETI. METHODS: Prospective, descriptive study at three German Helicopter Emergency Medical Services (HEMS) over a 1-yr period. We examined the success and complication rate for field intubation performed by trauma anaesthetists. RESULTS: In 342 patients (9.3%) ETI was performed. The overall success rate was 100%; in 87.4% the first attempt was successful, whereas in 11.1% a second and in 1.5% a third ETI attempt was necessary. No patient required a surgical intervention. Limited access to the patient was found upon arrival at the scene in 20.2% of the patients and in 9.6% of the patients at the time of ETI attempt. An orotracheal ETI technique was used in all patients. In the patients in whom only one ETI attempt was necessary for successful intubation, the assessment of ETI conditions was rated 'very good' or 'good' in 94.7%, but in those requiring a second or third ETI attempt this was reduced to 68.6 and 20.0%, respectively. Difficulties encountered during ETI included blood (19.9%), vomit/debris (15.8%) and secretions (13.8%) in the upper airway; anatomical reasons (11.7%), patient position (9.6%) and surrounding conditions (9.1%), making laryngoscopy more difficult. CONCLUSIONS: Despite various factors increasing the difficulties in managing the airway in the field, definitive airway control by ETI seems to be safe practice.

Adolescent↗

PubMed2005

[Invasive techniques in emergency medicine. III. Intraosseous punction--an alternative vascular access in paediatric emergencies].

There can be few more daunting challenges for the emergency physician than an infant or small child in shock or cardiac arrest. At the best of times, the combination of small veins and abundant subcutaneous tissue makes vascular access difficult or impossible, even in experienced hands. For these situations, the intraosseous vascular access is an easy, rapid and safe alternative. The intraosseous route is recommended for children < or =6 years of age, where conventional vascular access cannot be timely established. The preferred sites are the medial aspect of the proximal end of the tibia, just below the tibial tuberosity. Access should be obtained with a commercially available intraosseous needle. All emergency drugs and infusion fluids for intravenous usage can safely be infused via the intraosseous route (except hypertonic solutions) and it is not necessary to adjust drug dosage compared to the intravenous route. To avoid complications caused by the intraosseous needle, such as osteomyelitis, it should be replaced within 2 h by a conventional vascular access.

Anesthesia, General↗

PubMed2005

[How to assess the severity of the multi-system trauma in the emergency-room -- a critical review].

For more than 30 years various scoring systems have been used as a method to asses the injury severity of multi-system trauma. They have been used as a tool for triage, for emergency-room quality management, for educational reasons or, nowadays, in order to evaluate the cost effectiveness of either a complete hospital or a single department. This review provides the knowledge to score multi-system traumatized patients after their first treatment in the emergency-room. It shows advantages, disadvantages, and limitations of various traumascores which includes knowledge about the used parameters, the type of validation, the medical system in their country of origin, and of course their mathematical background. Relevant examples like physiological trauma scores (GCS, RTS, MEES), anatomic, injury pattern based scores (ISS, NISS, ICISS), biological aspects, mixed scoring systems (PTS, TRISS, ASCOT) and future developments ("Rixen-pattern", RISC) are illustrated. These scores are explained in detail and discussed as to their practicability.

Emergency Service, Hospital↗

PubMed2004

[Preclinical management of multiple trauma].

Approximately 8000 patients with multiple trauma are admitted annually to an emergency room in Germany. The prognosis of these severely injured patients is influenced in particular by concomitant craniocerebral injury, an abdominal wound, or thoracic trauma. Hypoxia and hypotension subsequent to shock induced by hemorrhagic-traumatic effects are of prime importance. Preclinical management thus includes examining the injured patient, immobilizing the spine, ensuring airway patency, stabilizing cardiovascular status suitting the approach to the injury pattern, commensurate care of partial injuries, pain therapy, as well as rapid and careful transportation to the nearest qualified trauma center. Management of patients with multiple trauma poses a particular challenge to the responding team. This article in the continuing education series deals with current algorithms for preclinical management of patients with multiple injuries with particular focus on the significant factor of time.

Blood Transfusion↗

PubMed2004

[Incidence of severe injuries. Results of a population-based analysis].

It is still unknown exactly how many persons sustain a severe injury (ISS > or =16) in Germany each year. Considering the growing restrictions and the introduction of DRGs, it was necessary to acquire data about this rather resource-intensive aspect of trauma care. The aim of this study was therefore to assess the incidence of severe trauma within a defined population. In a retrospective study all surgical emergencies within a 5-year period (1996-2000) were reviewed. Data on type, pattern, severity of injury, and mortality were extracted from the patients' records. During the study period 454 persons sustained a severe injury (ISS > or =16), 112 individuals died at the scene of the accident, and 64 during the hospital stay. The average ISS of the surviving patients was 27 (ISS 16-75). The calculated incidence of severe trauma was 25/100,000 inhabitants per year. Extrapolated, up to 40,000 persons sustain a severe injury each year in Germany. For the first time, this study has provided data on the incidence of major trauma in Germany. Based on the acquired data and a previous cost analysis, hospital treatment costs for severely injured patients amount to up to 2 billion Euros per year in Germany.

Adolescent↗

PubMed2003

[The future of preclinical emergency medicine in Germany].

Against the background of an ever-increasing shortage of financial support, closure of smaller hospitals and shortage of personnel in the medical branch, the necessity of the Federal emergency system is being increasingly called into question. In reality the number of missions which are relatively indicated are clearly increasing nationwide: an emergency doctor is not absolutely necessary in many situations. However, for complex emergency situations in Germany, an emergency medical system must remain an integral component of the preclinical care system in addition to the well-trained rescue service personnel. Hereby it is less important to have more emergency medical doctors, but more important to have a higher emergency medical qualification, possibly by a reduction in the density of emergency service stations. By the introduction of a ranked assistance system and the inclusion of "first responders", the time period before the arrival of the highly qualified emergency medical doctor can be bridged by qualified paramedics and general practitioners. The impulse of the legislators, assimilation of the rescue service acts, restructuring of rescue service catchment areas and the introduction of integrated demand-oriented control stations with a consequent quality management system as well as the implementation of a medical leader rescue system can reduce costs and further improve the quality of the emergency medical rescue system.

Allied Health Personnel↗

PubMed2003

Infrared-phonon-polariton resonance of the nonlinear susceptibility in GaAs.

Nonlinear probing of the fundamental lattice vibration of polar crystals is shown to reveal insight into higher-order cohesive lattice forces. With a free-electron laser tunable in the far infrared we experimentally investigate the dispersion of the second-order susceptibility due to the phonon resonance in GaAs. We observe a strong resonance enhancement of second harmonic light generation at half the optical phonon frequency, and in addition a minimum at a higher frequency below the phonon frequency. Measuring this frequency and comparison to a theoretical model allows the determination of competing higher-order lattice forces.

Journal Article↗

PubMed2003

[Emergency cricothyrotomy--puncture or anatomical preparation? Peculiarities of two methods for emergency airway access demonstrated in a cadaver model].

OBJECTIVES: The aim of the study was a demonstration of peculiarities of two invasive airway management methods performed by anesthesiology residents as a subgroup of emergency physicians. METHODS: During an airway management training seminar,2 groups including 18 anaesthesiology residents and 2 students performed a simulated emergency surgical cricothyrotomy on unfixed cadavers. The more experienced physicians in group 2 started with a puncture technique preceding a blind surgical approach. The time needed to perform each procedure and resulting complications were analyzed. RESULTS: The time taken ranged from 75 to 280 s (median 180 s) in group 1 and from 53 to 255 s (median 73 s) in group 2. The surgical approach caused "bleeding" in 40% (group 1) and 30% (group 2) and damage to the cartilages occurred in 20% and 30%, respectively. Punctures were performed within 10-36 s (median 25 s) and 70% were successful without complications. CONCLUSIONS: Puncture of the cricothyroid membrane can serve as initial emergency approach or as intermediate airway access until a surgical method is available.

Anesthesiology↗

PubMed2003

Environmental temperature stress on drugs in prehospital emergency medical service.

BACKGROUND: Drugs used in prehospital emergency medical service (EMS) in principle are subject to the same storage restrictions as hospital-based medications. The prehospital emergency environment however, often exceeds these storage recommendations. Main stress factors are sunlight, vibration and extreme temperature, which may lead to alteration in chemical and physical stability of stored pharmaceuticals, as well as microbiological contamination and concentration enhancement of pharmacological inserts. METHODS: The purpose of this study was to determine the environmental temperature stress upon drugs used in the prehospital EMS under real mission conditions within different types of rescue vehicles (rescue helicopter [HEMS], ambulance [AMB] and emergency physician transport vehicle [EPTV]) during a 'summer' and 'winter' monitoring period (2 months duration each/location: southern Germany). RESULTS: Recorded temperatures varied from -13.2 degrees C to +50.6 degrees C. The recommended maximum storage temperature (+25 degrees C) was exceeded in all rescue vehicles (33-45% of total exposure time), whereas the recommended minimum storage temperature (0 degrees C) only fell short in the EPTV (19% of total exposure time). The daily maximum temperature variations ranged from 19.0 degrees C (winter) to 32.9 degrees C (summer). CONCLUSIONS: These results show that even in a moderate climatic zone, drugs used in prehospital EMS are significantly influenced by temperature stress; furthermore, these results recommend the usage of temperature-controlled drug boxes.

Air Ambulances↗

PubMed2003

Tight control of prehospital ventilation by capnography in major trauma victims.

BACKGROUND: Tracheal intubation combined with controlled ventilation of the lungs is an important part of the prehospital management of major trauma victims, but gauging the adequacy of ventilation remains a major problem. METHODS: Ninety-seven major trauma victims who underwent tracheal intubation in the field and controlled ventilation of the lungs during prehospital treatment by a Helicopter Emergency Medical Service were assigned randomly to one of two groups: (1) monitor group (n=57) and (2) monitor-blind group (n=40), according to whether the anaesthetist could or could not see an attached capnograph screen. In the monitor-blind group ventilation was set by using a tidal-volume of 10 ml kg(-1) estimated body weight and an age-appropriate ventilatory frequency. In the monitor group, ventilation was adjusted to achieve target end-tidal carbon dioxide values determined by the 'physiological state' of the trauma victim. Arterial blood gases were measured upon hospital admission while maintaining the ventilation initiated in the field and the Pa(CO(2)) value obtained was used as the determinant of the adequacy of prehospital ventilation. RESULTS: The incidence of 'normoventilation' was significantly higher (63.2 vs 20%; P<0.0001) and the incidence of 'hypoventilation' upon hospital admission was significantly lower (5.3 vs 37.5%; P<0.0001) in the monitor group; patients with severe head and chest trauma and haemodynamically unstable patients and those with a high injury severity score were significantly more likely to be 'normoventilated' upon hospital admission in the monitor group than in the monitor-blind group. CONCLUSIONS: The data support the routine use of prehospital capnographic monitoring using target end-tidal carbon dioxide values adapted to the physiological state of the patient in major trauma victims requiring tracheal intubation in the field.

Adolescent↗

PubMed2002

Two crossovers in the Pseudogap regime of YBa 2Cu 3O (7-delta) superconductors observed by ultrafast spectroscopy.

We have investigated the temperature dependence of the optical reflectivity on a femtosecond scale in a near optimally doped YBa 2Cu 3O (7-delta) superconductor. The combined study of the lattice and carrier dynamics at temperatures above T(c) allows us to identify two crossover temperatures in the normal state, giving evidence for an inhomogeneity of the pseudogap regime. These crossovers exhibit a clear hysteresis behavior depending on the direction of temperature change. The carrier and lattice dynamics within the crossover regimes show distinct differences from and similarities to the superconducting state, which may help in choosing between the competing theories for the pseudogap state.

Journal Article↗

PubMed2002

A prospective study of the quality of pre-hospital emergency ventilation in patients with severe head injury.

BACKGROUND: Pre-hospital endotracheal intubation for the purpose of controlled ventilation may prevent secondary brain injury in patients with severe head injury. In view of the limited monitoring devices utilized in the pre-hospital setting, little is known about the 'quality' of controlled ventilation initiated in the pre-hospital setting. METHODS: Included in this prospective study were 122 trauma patients with severe head injury (abbreviated injury scale score > or = 3). In all cases, the pre-hospital treatment included endotracheal intubation in the field. Upon hospital admission, and maintaining the same ventilation mode and setting initiated in the pre-hospital setting, arterial blood gas samples were taken. RESULTS: 'Optimal' oxygenation (PaO2 > 100 mm Hg) was achieved in 85.2% and 'adequate' ventilation (PaCO2 35-45 mm Hg) in 42.6% of the patients upon hospital admission. 'Optimal' oxygenation as well as 'adequate' ventilation was achieved in 37.7% of the study population. Hypoxaemia (PaO2 < 60 mm Hg) was observed in 2.5%, hypercapnia (PaCO2 > 45 mm Hg) in 16.4%, and hypocapnia (PaCO2 < 35 mm Hg) in 40.9% of the study patients. The incidence of hypocapnia was significantly more frequent in polytraumatized patients. Hypocapnia as well as hypercapnia was significantly more frequent in patients with associated pulmonary contusion. CONCLUSIONS: Endotracheal intubation and controlled ventilation of the lungs initiated in the pre-hospital setting do not guarantee optimal oxygenaton and ventilation in patients with severe head injury.

Adolescent↗

PubMed2001

The plant tRNA 3' processing enzyme has a broad substrate spectrum.

To elucidate the minimal substrate for the plant nuclear tRNA 3' processing enzyme, we synthesized a set of tRNA variants, which were subsequently incubated with the nuclear tRNA 3' processing enzyme. Our experiments show that the minimal substrate for the nuclear RNase Z consists of the acceptor stem and T arm. The broad substrate spectrum of the nuclear RNase Z raises the possibility that this enzyme might have additional functions in the nucleus besides tRNA 3' processing. Incubation of tRNA variants with the plant mitochondrial enzyme revealed that the organellar counterpart of the nuclear enzyme has a much narrower substrate spectrum. The mitochondrial RNase Z only tolerates deletion of anticodon and variable arms and only with a drastic reduction in cleavage efficiency, indicating that the mitochondrial activity can only cleave bona fide tRNA substrates efficiently. Both enzymes prefer precursors containing short 3' trailers over extended 3' additional sequences. Determination of cleavage sites showed that the cleavage site is not shifted in any of the tRNA variant precursors.

Anticodon↗

PubMed2001

RNase activity of a DNA minor groove binder with a minimalist catalytic motif from RNase A.

Imidazole and compounds containing imidazole residues have been shown to cleave RNA in an RNase A-mimicking manner. Di-imidazole lexitropsin is a compound which is derived from the polyamide drugs distamycin and netropsin essentially by the replacement of two pyrrole heterocycles with N-methyl-imidazole residues. This enables it to bind to the minor groove of B-DNA in a sequence-specific manner. We demonstrate here that this lexitropsin derivative has RNA cleavage activity, as tested on model RNAs. Optimal cleavage conditions and cleavage specificity resemble those known from other imidazole conjugates and are thus consistent with an RNase A type cleavage mechanism. The optimum concentration of the compound for cleavage is similar to previously investigated imidazole-based RNase mimics. As a whole new class of chemical compounds capable of interacting with nucleic acids through extensive hydrogen bonding, these imidazole containing compounds constitute promising scaffolds and ligands, for the construction of novel RNase mimics with high affinity.

Animals↗

PubMed2000

Search for characteristic structural features of mammalian mitochondrial tRNAs.

A number of mitochondrial (mt) tRNAs have strong structural deviations from the classical tRNA cloverleaf secondary structure and from the conventional L-shaped tertiary structure. As a consequence, there is a general trend to consider all mitochondrial tRNAs as "bizarre" tRNAs. Here, a large sequence comparison of the 22 tRNA genes within 31 fully sequenced mammalian mt genomes has been performed to define the structural characteristics of this specific group of tRNAs. Vertical alignments define the degree of conservation/variability of primary sequences and secondary structures and search for potential tertiary interactions within each of the 22 families. Further horizontal alignments ascertain that, with the exception of serine-specific tRNAs, mammalian mt tRNAs do fold into cloverleaf structures with mostly classical features. However, deviations exist and concern large variations in size of the D- and T-loops. The predominant absence of the conserved nucleotides G18G19 and T54T55C56, respectively in these loops, suggests that classical tertiary interactions between both domains do not take place. Classification of the tRNA sequences according to their genomic origin (G-rich or G-poor DNA strand) highlight specific features such as richness/poorness in mismatches or G-T pairs in stems and extremely low G-content or C-content in the D- and T-loops. The resulting 22 "typical" mammalian mitochondrial sequences built up a phylogenetic basis for experimental structural and functional investigations. Moreover, they are expected to help in the evaluation of the possible impacts of those point mutations detected in human mitochondrial tRNA genes and correlated with pathologies.

Acylation↗

PubMed2000

Phenotypic HIV-1 resistance correlates with treatment outcome of nelfinavir salvage therapy.

In order to analyse whether drug sensitivity testing would be beneficial for clinical decision-making in heavily pretreated patients, we retrospectively studied viral genotype and phenotypic drug resistance in 12 HIV-1-infected patients, each of them with a history of failing at least one therapeutic regimen including one or two protease inhibitors (PIs). The salvage therapy included nelfinavir as new PI in all cases. Four patients showed a sustained and five patients a transient viral load decrease. Three patients failed to show a significant decline of plasma HIV-1 RNA. In the baseline samples of these cases, resistance against all components of their combination therapy could be detected, whereas at least one antiretroviral drug was still active in the cases with transient treatment response. All patients with sustained therapy response harboured viruses that were either fully sensitive or resistant to only one of the drugs administered. In our study, phenotypic drug resistance was predictive for the success of antiretroviral salvage regimens.

Amino Acid Sequence↗

PubMed1999

A Watson-Crick base-pair-disrupting methyl group (m1A9) is sufficient for cloverleaf folding of human mitochondrial tRNALys.

We have previously shown by chemical and enzymatic structure probing that, opposite to the native human mitochondrial tRNA(Lys), the corresponding in vitro transcript does not fold into the expected tRNA-specific cloverleaf structure. This RNA folds into a bulged hairpin, including an extended amino acid acceptor stem, an extra large loop instead of the T-stem and loop, and an anticodon-like domain. Hence, one or several of the six modified nucleotides present in the native tRNA are required and responsible for its cloverleaf structure. Phylogenetic comparisons as well as structural analysis of variant transcripts had pointed to m(1)A9 as the most likely important modified nucleotide in the folding process. Here we describe the synthesis of a chimeric tRNA(Lys) with m(1)A9 as the sole modified base and its structural analysis by chemical and enzymatic probing. Comparison of this structure to that of the unmodified RNA, the fully modified native tRNA, and a variant designed to mimic the effect of m(1)A9 demonstrates that the chimeric RNA folds indeed into a cloverleaf structure that resembles that of the native tRNA. Thus, due to Watson-Crick base-pair disruption, a single methyl group is sufficient to induce the cloverleaf folding of this unusual tRNA. This is the first direct evidence of the role of a modified nucleotide in RNA folding.

Adenine↗