Monoenergetic ion beam generation by driving ion solitary waves with circularly polarized laser light.

Experimental data from the Trident Laser facility is presented showing quasimonoenergetic carbon ions from nm-scaled foil targets with an energy spread of as low as ±15% at 35 MeV. These results and high-resolution kinetic simulations show laser acceleration of quasimonoenergetic ion beams by the generation of ion solitons with circularly polarized laser pulses (500 fs, λ=1054 nm). The conversion efficiency into monoenergetic ions is increased by an order of magnitude compared with previous experimental results, representing an important step towards applications such as ion fast ignition.

Enhanced laser-driven ion acceleration in the relativistic transparency regime.

We report on the acceleration of ion beams from ultrathin diamondlike carbon foils of thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities of approximately 7 x 10;{19} W/cm;{2}. An unprecedented maximum energy of 185 MeV (15 MeV/u) for fully ionized carbon atoms is observed at the optimum thickness of 30 nm. The enhanced acceleration is attributed to self-induced transparency, leading to strong volumetric heating of the classically overdense electron population in the bulk of the target. Our experimental results are supported by both particle-in-cell (PIC) simulations and an analytical model.

Laser-driven shock acceleration of ion beams from spherical mass-limited targets.

We report on experimental studies of ion acceleration from spherical targets of diameter 15 microm irradiated by ultraintense (1x10(20) W/cm2) pulses from a 20-TW Ti:sapphire laser system. A highly directed proton beam with plateau-shaped spectrum extending to energies up to 8 MeV is observed in the laser propagation direction. This beam arises from acceleration in a converging shock launched by the laser, which is confirmed by 3-dimensional particle-in-cell simulations. The temporal evolution of the shock-front curvature shows excellent agreement with a two-dimensional radiation pressure model.

Radiation-pressure acceleration of ion beams driven by circularly polarized laser pulses.

We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast laser pulses of energy 0.7 J focused to peak intensities of 5x10(19) W/cm2. A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those C6+ ions are for the first time dominantly accelerated in a phase-stable way by the laser radiation pressure.

Anisotropic explosions of hydrogen clusters under intense femtosecond laser irradiation.

We report on measurements of ion energy distributions from hydrogen clusters irradiated by intense laser pulses of duration 40 and 250 fs. Contrary to the predictions of a simple Coulomb explosion model, we observe a pronounced spatial anisotropy of the ion energies from these explosions with the highest energy ions ejected along the laser polarization direction. The origin of the anisotropy is distinct from that previously seen in clusters of high Z atoms such as Ar and Xe. Furthermore, a measured increase in H+ ion energy when longer, lower intensity pulses are employed suggests that multiple-pass, vacuum heating of the cluster electrons is important in the deposition of energy by the laser.

Prevalence, predictors and patterns of postoperative polyuria and hyponatraemia in the immediate course after transsphenoidal surgery for pituitary adenomas.

OBJECTIVE: Disturbances of osmoregulation, leading to diabetes insipidus and hyponatraemia are well known complications after surgery in the sella region. This study was performed to examine the prevalence and predictors of polyuria and hyponatraemia after a complete and selective removal of pituitary adenomas was attempted via the transnasal-transsphenoidal approach. DESIGN: 1571 patients with pituitary adenomas (238 Cushing's disease, 405 acromegaly, 534 hormonally inactive adenomas, 358 prolactinoma, 23 Nelson's syndrome, and 13 thyrotropinoma) were daily examined within a 10-day postoperative inpatient observation period. Prevalence of patterns of polyuria (> 2500 ml) and oliguria/hyponatraemia (< 132 mmol/l) were surveyed as well as predictors of postoperative morbidity. RESULTS: 487 patients (31%) developed immediate postoperative hypotonic polyuria, 161 patients (10%) showed prolonged polyuria and 37 patients (2.4%) delayed hyponatraemia. A biphasic (polyuria-hyponatraemia) and triphasic (polyuria-hyponatraemia-polyuria) pattern was seen in 53 (3.4%) and 18 (1.1%) patients, respectively. Forty-one patients (2.6%) displayed immediate postoperative (day 1) hyponatraemia. Altogether, 8.4% of patients developed hyponatraemia at some time up to the 10th day postoperative, with symptomatic hyponatraemia in 32 patients (2.1%). Risk analysis showed that patients with Cushing's disease had a fourfold higher risk of polyuria than patients with acromegaly and a 2.8-fold higher risk for postoperative hyponatraemia. Younger age, male sex, and intrasellar expansion were associated with a higher risk of hypotonic polyuria, but this was not considered clinically relevant. CONCLUSIONS: The analysis illustrates that disturbances in osmoregulation resulting in polyuria and pertubations of serum sodium concentration are of very high prevalence and need observation even after selective transsphenoidal surgery for pituitary adenomas, especially in patients with Cushing's disease.

Severe hyponatremia after transsphenoidal surgery for pituitary adenomas.

Severe hyponatremia has been described after elective surgery with subsequent permanent brain damage. Other authors, however, have noted that morbidity and mortality rates of severe hyponatremia have been greatly overestimated. We retrospectively examined 19 patients (8 male, 11 female) who developed severe hyponatremia (100 to 124 mmol/liter) after transsphenoidal surgery for pituitary adenomas. Eight patients had hormonally inactive adenomas, 5 ACTH-secreting adenomas, 2 GH-secreting adenomas and 4 prolactin-secreting adenomas. The mean age of the patients was 47.5 years, with a range from 16 to 71 years. The mean preoperative serum sodium level was 137.8 mmol/liter. The timing of hyponatremia showed two different patterns. Five patients developed early postoperative hyponatremia (mean 114.0 mmol/liter +/- 4.85) and 14 patients showed the lowest mean serum level one week after surgery (118.1 mmol/liter +/- 6.86). Patients with early hyponatremia had fewer and less severe symptoms than patients with delayed hyponatremia. None of the patients developed seizures or a demyelination syndrome. Despite severe degree of hyponatremia for most of our patients treatment with water restriction and oral sodium supplementation was sufficient.

The efficacy of integrating "smart simulated casualties" in hospital disaster drills.

INTRODUCTION: Full-scale disaster drills are complex, expensive, and may involve hundreds or thousands of people. However, even when carefully planned, they often fail to manifest the details of medical care given to the casualties during the drill. OBJECTIVE: To assess the feasibility of integrating physicians among the simulated casualties of a hospital disaster drill. METHODS: A total of 178 physicians graduating an Advanced Trauma Life Support (ATLS) course participated in eight hospital disaster drills during 1994 as "Smart Victims." The participants were given cards with descriptions of their injury and detailed instructions on how to manipulate their medical condition according to the medical care provided in the hospital. They also were given coded questionnaires to fill out during the process of the drill. Conclusions were drawn from analysis of the questionnaires and from a roundtable discussion following each drill. RESULTS: The "smart casualties" made comments on the following topics: 1) triage (over-triage in 9%, and under-triage in 4%); 2) treatment sites; 3) medical equipment usage (i.e., shortage of ventilators and splinting devices); 4) medical knowledge and care rendered by the hospital staff; 5) evacuation and escorting of the wounded; 6) management of patients with post-traumatic stress disorder; and 7) medical documentation. Their comments contributed valuable information on the quality of medical care and organization, and identified obstacles that otherwise would have been overlooked. The "smart casualties" were very cooperative and indicated that their participation in the drill contributed to their understanding of disaster situations in hospitals. CONCLUSION: Integrating physicians among the simulated casualties in a hospital disaster drill may contribute to achieving the objectives of hospital disaster drills and add to disaster management education of the simulated casualty physicians.

Ketamine in the field: the use of ketamine for induction of anaesthesia before intubation in injured patients in the field.

Intubating the subconscious, struggling patient in a pre-hospital setting can be a difficult task even in experienced hands. We performed a clinical prospective study to evaluate the applicability of ketamine for induction of anaesthesia before intubation in the field. Ketamine was distributed to all air medical rescue teams--trained reserve army volunteers from various medical specialties. Lectures and literature concerning the use of ketamine for anaesthesia induction before intubation were given. The physicians were instructed to administer ketamine, in a dose of 2 mg/kg intravenously, if a single intubation attempt failed. Following the administration of ketamine, a questionnaire was filled in by the physician. Analysis of the data was performed after 24 months. During the study period, intubation was indicated in 161 injured patients evacuated by air in Israel. In 29 patients (18 per cent) the first intubation attempt had failed and they were given ketamine. The reasons for failure of the first intubation attempt were restlessness or trismus in 23 patients and traumatic distortion of the upper airway anatomical landmarks in six. Following ketamine administration, intubation was successful in 19 patients (65.5 per cent) in all of whom the indication for ketamine administration was restlessness or trismus. All patients with upper airway anatomy distortion were given a cricothyroidotomy. There were no complications attributed to ketamine. All patients reached hospital alive. This preliminary study suggests that the use of ketamine in this pre-hospital setting is safe. The drug is effective in cases where the primary reason for failure to intubate is restlessness or trismus. The drug is not effective in cases of anatomical damage to the upper airway. In these cases, cricothyroidotomy should probably be performed as early as possible.

[Coniotomy: surgical airway management in trauma before hospitalization].

To assess the efficacy of prehospital coniotomy (cricothyrotomy), information regarding all coniotomies performed by military physicians during the last 3.5 years was analyzed. 26 were performed between October 1991 and May 1995, of which 23 were successful (88.4%). Failures were due to poor anatomic identification of the cricothyroid membrane. Most patients suffered head or neck injuries (in 61.5% and 19%, respectively). The main indications were anatomical distortion of the pharynx and larynx and failure to intubate. Intubation was attempted in 22 patients prior to coniotomy (multiple attempts in 17). Since coniotomy is a life-saving procedure, it should be part of the armamentarium of any physicians. Coniotomy in the field is associated with a high success rate. The procedure is recommended in trauma victims who need airway establishment and cannot be intubated or in whom intubation has failed.

[Medical kits in Army physicians' vehicles].

Physicians' medical kits (PMK) were distributed to 50 physicians, graduates of an advanced trauma life support course. The kits were always to be present in the physicians' designated vehicles, enabling them to provide advanced life support at the earliest possible stage (the "golden hour"). The kits have equipment for advanced airway intervention and management, chest trauma management (chest tube insertion, etc.) and fluid administration. To help assess the impact of the PMK and its cost effectiveness, questionnaires were sent to the physicians involved, of whom 35/50 responded. The questions included 2 subjects: the presence of the kit in the car and details of its use for injuries. The kit was present at all times in the cars of all except 1 of 31 physicians. 7 (22.5%) of them used the kit in 50 incidents which involved 74 injured persons. The injuries were caused by road accidents in 54 cases, in 17 by terrorist activity, and 3 cases involved heart attacks and cardiac resuscitation. Distribution of the PMK among army physicians appears to be valuable in the field, and before hospitalization.

Gentamycin serum levels in a patient with severe skin damage.

Pseudomonas aeruginosa grew in blood cultures taken from a 30-year-old woman with a 45% burn of second and third degree. Because of wound infection, skin grafting was unsuccessful and the wounds were left uncovered and treated topically with Eusol and saline solution. During this period 7 mg/kg gentamycin was administered to the patient daily; the blood level of the antibiotic was 3 microgram/ml, rather than the expected 8--12 microgram/ml in a patient without burns. On the eighth day, 40% of the administered dose was recoverable in the urine. With partial covering of the wounds, a dose of 5 mg/kg gentamycin daily gave blood levels of 6.5 microgram/ml. When most of the burn wounds were covered, a dose of 5 mg/kg gentamycin daily gave a blood level of 12 microgram/ml. Kidney function remained normal throughout the whole period. The possibility that gentamycin was eliminated through the burn wounds is suggested.