Malaria prophylaxis and self-therapy in airline crews

The risk of malaria infection in airline crews is estimated to be 0.5 per 1,000 persons per night in areas with high levels of malaria transmission. Routine chemoprophylaxis for years is not recommended because of possible side effects. Airline crews should therefore use appropriate measures to prevent mosquito bites. In addition, they may need to carry "standby" medication with them to be used for presumptive treatment of a febrile illness if medical attention is not readily available.     

Sustained operations of artillery crews in NBC and non-NBC environments

The capability of artillery crews to perform fire missions was studied as a function of sustained time on the task and clothing condition. Crews wearing either the standard Army field duty uniform (BDU) or a chemical protective ensemble (MOPP gear) attempted to conduct missions for up to 24 hours. Each of three MOPP crews were able to perform for only a limited time (about 2 hours), primarily because they had problems working in a hot environment (approximately 90 degrees F). A BDU crew completed its scenario, which was conducted under similar environmental conditions. Times to fire rounds were much greater in the MOPP crews than the BDU crew, exemplifying the performance difficulties associated with wearing a bulky, restrictive ensemble that can degrade important skills and functions.     

Normobaric hypoxia inhalation test vs. response to airline flight in healthy passengers

INTRODUCTION: There is little data available to determine the normal response to normobaric hypoxia inhalation testing (NHIT) and air travel. Quantifying a healthy response may assist in the evaluation of passengers considered at risk for air travel. The aims of this study were: (1) to quantify the degree of desaturation in healthy subjects during a NHIT and air travel; and (2) assess the validity of the NHIT when compared with actual in-flight responses. METHODS: There were 15 healthy adults (age 23-57; 10 women) who volunteered for this study. Preflight tests included lung function, arterial blood gas, pulse oximetry (SpO2), and NHIT (inspired oxygen 15%). SpO2 and cabin pressure were measured continuously on each subject during a commercial air flight (mean cabin altitude 2178 m; range 1719-2426 m). In-flight oxygenation was compared with the preflight NHIT. RESULTS: Lung function testing results were normal. There was significant desaturation (SpO2) during the NHIT (pre: 98 +/- 2%; post: 92 +/- 2%) and at cruising altitude (pre: 97 +/- 1%; cruise: 92 +/- 2%). There was no difference between the final NHIT SpO2 and the mean in-flight SpO2. There was a significant difference between the lowest in-flight SpO2 (88 +/- 2%) vs. the lowest NHIT SpO2, (90 +/- 2%). DISCUSSION: Oxygen saturation decreases significantly during air travel in normal individuals. In this group of healthy passengers the NHIT approximates some, but not all, aspects of in-flight oxygenation. These results can be used to describe a normal response to the NHIT and air-travel.     

MR imaging of the cervical spine: techniques for two- and three-dimensional imaging.

This review briefly describes two-dimensional (2D) and three-dimensional (3D) MR imaging of the cervical spine and focuses on the current and potential clinical usefulness of 3D sequences in the evaluation of cervical spine abnormalities. The practical advantages of 3D imaging are several, and include an increase in signal-to-noise ratio over 2D imaging, thin contiguous slices, more accurate slice thickness, and optimal computer postprocessing. Different 3D techniques can provide either high- or low-signal-intensity CSF, with excellent suppression of CSF pulsation artifacts.     

Risk factors for deep vein thrombosis in short-haul cockpit crews: a prospective study

BACKGROUND: Venous thrombosis is a concern receiving international attention, especially for passengers traveling on long distance flights. However, there are no data on the effect on cockpit crew of multiple short duration flights. METHODS: Cockpit crew flew two or more internal flights per day. At sign on, 15 ml of blood was venesected from the subjects; at sign off, 20 ml of blood was venesected. All flights originated and terminated at Johannesburg Airport. A full blood count, differential, and D-dimer levels were determined. All participants completed detailed questionnaires stating their ages, alcohol consumption 24 h prior to flight duty, the amount of liquid consumed during flying time, the number of times they went to the toilet, and the amount of time spent sitting during flights. RESULTS: Blood tests on 27 cockpit crew were performed. D-dimers were reduced from 163 ng x ml(-1) to 133 ng x ml(-1) (p = 0.03). Hemoglobin levels dropped from 16.0 g x dl(-1) to 15.8 g x dl(-1) (p = 0.004). Hematocrit levels decreased from 47.2 ml x 100 ml(-1) to 46.9 ml x 100 ml(-1) (p = 0.04). Platelets increased from 221 x 10(9) x L(-1) to 241 x 10(9) x L(-1) (p = 0.001). White cell counts increased from 6.4 x 10(9) x L(-1) to 7.01 x 10(9) x L(-1) (p = 0.0063). Correlation analysis was performed between blood test results and the parameters of the questionnaire. No correlation was found between any of the parameters and the blood results. CONCLUSION: There is no evidence of sub-clinical thrombotic events in this group of subjects. Cockpit crew who fly multiple short duration flights do not suffer sub-clinical thrombotic events as evidenced by an absence of increased D-dimers.     

Measurement of brain structures with artificial neural networks: two- and three-dimensional applications.

PURPOSE: To evaluate the ability of an artificial neural network (ANN) to identify brain structures. This ANN was applied to postprocessed magnetic resonance (MR) images to segment various brain structures in both two- and three-dimensional applications. MATERIALS AND METHODS: An ANN was designed that learned from experience to define the corpus callosum, whole brain, caudate, and putamen. Manual segmentation was used as a training set for the ANN. The ANN was trained on two-thirds of the manually segmented images and was tested on the remaining one-third. The reliability of the ANN was compared against manual segmentations by two technicians. RESULTS: The ANN was able to identify the brain structures as readily and as well as did the two technicians. Reliability of the ANN compared with the technicians was 0.96 for the corpus callosum, 0.95 for the whole brain, 0.86 (right) and 0.93 (left) for the caudate, and 0.71 (right) and 0.88 (left) for the putamen. CONCLUSION: The ANN was able to identify the structures used in this study as well as did the two technicians. The ANN could do this much more rapidly and without rater drift. Several other cortical and subcortical structures could also be readily identified with this method.     

Pain in knee arthrography: comparison of air vs. CO2 and reaspiration vs. no reaspiration

A prospective study of 255 patients undergoing double-contrast arthrography of the knee was performed to evaluate postexamination knee pain after two procedural modifications: (1) intraarticular carbon dioxide versus room air and (2) postprocedural joint reaspiration versus no reaspiration. A moderate or severe increase in pain during the 24 hr after the examination was experienced by 20% of patients. Carbon dioxide resulted in slightly greater patient pain immediately after the procedure than did room air. However, there was no difference in morbidity in these two groups at 24 hr. Aspiration of the knee joint had no immediate or delayed effect on patient pain. Older patients, women, and patients with abnormal arthrograms, reported more baseline discomfort but, allowing for this, they tolerated the procedure as well as younger patients, men, and patients with normal arthrograms. It is recommended that double contrast arthrography of the knee be performed using intraarticular air without reaspiration of the joint.     

Minimizing TE in moment-nulled or flow-encoded two- and three-dimensional gradient-echo imaging.

A method for minimizing field-echo delay in moment-nulled gradient-echo imaging is presented. Even though ramps are accounted for, the analysis yields simple closed-form solutions. The method is then generalized to the section-select waveform for three-dimensional volume imaging and to flow encoding for phase-contrast imaging. Three strategies for first-moment selection in phase-contrast imaging are discussed, including a new strategy that always yields the minimum echo delay. Trapezoidal and triangular gradient lobe shapes are analyzed.     

Perceived fatigue for short- and long-haul flights: a survey of 739 airline pilots

BACKGROUND: Fatigue-related incidents in aviation may be self-reported by pilots in confidential systems. The aim of this study was to clarify what fatigue means to pilots on short- and long-haul flights (SHF and LHF, respectively). METHODS: Questionnaires were distributed to pilots through four airlines. Questions concerned the perceived causes of fatigue, its signs and symptoms in the reporting pilot and observed in others, as well as the strategies used to minimize its impact. RESULTS: Of 3,436 questionnaires distributed, 739 (21.5%) were returned. For LHF, fatigue was seen as mainly due to night flights (59%) and jet lag (45%). For SHF, fatigue was caused by prolonged duty periods (multi-segment flights over a sequence of 4 to 5 d) (53%) and successive early wake-ups (41%). Self-reported manifestations of fatigue in 60% of LHF pilots and 49% of SHF pilots included reduction in alertness and attention, and a lack of concentration. Signs observed in other crewmembers included an increase in response times and small mistakes (calculation, interpretation). When pilots were tired, all the flying tasks seemed to be more difficult than usual. In both LHF and SHF, rest and sleep management were the primary strategies used to cope with fatigue. Analysis showed that duty time is a major predictor of fatigue, but that it cannot be considered independently from the other contributory factors. CONCLUSION: For both LHF and SHF, pilots reported acute fatigue related to sleep deprivation, due mainly to work schedules: night flights, jet-lag, and successive early wake-ups. These causal factors could easily be assessed in investigation of accidents and incidents.     

Functional imaging in the assessment of myocardial infarction: MR imaging vs. MDCT vs. SPECT

Purpose

To intraindividually compare magnetic resonance (MR) imaging, ECG-gated multi-detector spiral computed tomography (MDCT) and gated single photon emission computed tomography (SPECT) for the evaluation of global and regional myocardial function and the identification of myocardial perfusion abnormalities.

Materials and methods

Nine patients (8 men; 55.1 ± 8.9 years) with a history of myocardial infarction (MI) were included in this retrospective study. All patients had undergone segmented k-space steady state free precession MR imaging, ^99mTc-MIBI gated myocardial perfusion SPECT and contrast enhanced ECG-gated 16-MDCT. Ventricular volumes and ejection fraction (EF) were calculated. Left ventricular (LV) wall motion at rest was analyzed. For SPECT and arterial phase MDCT perfusion abnormalities were assessed. Data was compared with Lin's concordance-correlation coefficient (ρ_c), Bland-Altman plots and kappa statistics.

Results

For EF, there was an excellent concordance and correlation (ρ_c = 0.99) between SPECT (EF = 41.7 ± 10.4%), MDCT (EF = 42.2 ± 11.1%), and MR imaging (EF = 41.9 ± 11.4%). Considering MR imaging as standard of reference, MDCT (κ = 0.86) is superior to SPECT (κ = 0.51) for the assessment of the regional wall motion at rest. There was a good agreement between SPECT and MDCT regarding the detection of perfusion abnormalities (κ = 0.62).

Conclusion

MDCT, MR imaging, and SPECT allow for the reliable assessment of global and regional left ventricular function in patients with a history of MI. MDCT also allows to some extent for the detection of perfusion abnormalities. With its potential to assess both, the coronary arteries as well as the myocardium, MDCT a promising modality for the comprehensive diagnostic work-up in patients with suspected myocardial ischemia.     

The use of cardiac and eye blink measures to determine flight segment in F4 crews.

Discriminant analysis techniques were used to classify 8 flight segments for 19 F4 crewmembers and to classify pilots from Weapons Systems Officers (WSOs). Heart rate and eye blink data were used as variables. Pilots and WSOs were correctly classified 84% of the time, while 92% of the flight segments were correctly classified for pilots and 89% for WSOs. The percent correct classifications of flight segments using the jackknife procedure were 69% and 68%, respectively. The advantage of collecting multiple physiological signals was demonstrated. Combined cardiac and eye blink data produced better classifications than when each was used alone. Application of this technique to the flight environment is discussed.     

Double calibration vs. global optimisation: performance and effectiveness for clinical application

For clinical application the quantification of the actual subject-specific kinematics is necessary. Soft tissue artefact (STA) propagation to joint kinematics can nullify the clinical interpretability of stereophotogrammetric analysis. STA was assessed to be strongly subject- and task-specific. The global optimisation, whose performance was assessed only on simulated data, is at the basis of several of the STA compensation methods proposed in the literature. On the other hand, the double calibration was recently proposed and resulted very effective on experimental data. In the present work, the performance of double calibration and global optimisation in reducing soft tissue artefact propagation to relevant knee joint kinematics was compared by using 3D fluoroscopy as gold standard. The mean RMSE over the repetitions for the double calibration is in the order of 1-2 degrees for joint rotations and 1-3 mm for translation, while for the global optimisation is in the order of 10 degrees and 10-15 mm, respectively. The double calibration should then be preferred for the quantification of the subject specific kinematics.     

Whole-body MRI vs. CT for staging lymphoma: Patient experience

Objective

To assess and compare patient experience of whole-body magnetic resonance imaging (MRI) to that of computed tomography (CT) for staging newly diagnosed lymphoma.

Materials and methods

A total of 36 patients with newly diagnosed lymphoma prospectively underwent whole-body MRI and CT for staging purposes. Patients were asked to fill in a short questionnaire with regard to the burden and experience of the examination on a Likert scale (range 1–4). Wilcoxon signed rank tests were used to determine statistically significant differences in patient (dis)comfort between the two examinations.

Results

Patients reported to be significantly (P = 0.007) less worried before undergoing whole-body MRI compared to CT. Patients also experienced whole-body MRI as significantly (P = 0.010) less unpleasant and felt significantly (P = 0.003) better shortly after the scan. The necessary preparations before CT scanning (i.e. insertion of intravenous line, drinking of contrast fluid), which are not required for whole-body MRI, were reported to be a considerable burden.

Conclusion

In this study in patients with newly diagnosed lymphoma, whole-body MRI was experienced as a more patient-friendly technique than CT.     

Central retinal artery occlusion by proxy: a cause for sudden blindness in an airline passenger

The use of gas media in ophthalmologic procedures is relatively commonplace. Scleral buckle and pneumatic retinopexy procedures using air-gas mediums are a widely accepted treatment for retinal detachment. We present a patient who had a scleral buckle with pneumatic retinopexy performed and subsequently flew in a commercial airliner 2 wk later. The patient experienced sudden blindness due to central retinal artery occlusion brought about by expansion of the air bubble when the aircraft reached cruise altitude and a cabin pressure of 8000 ft. The intraocular pressure exceeded the central artery pressure thereby collapsing the artery. The patient's symptoms were relieved when an onboard flight surgeon identified the problem and the cabin pressure was reset to 2000 ft. Flying after an ophthalmic procedure that incorporates intraocular gas may have complications due to the bubble expansion in accordance with Boyle's Law. The ophthalmologic surgeon must be diligent in forewarning patients of the potential complications of flying for weeks to months after a procedure that utilizes intraocular gas.     

Elastic energy in locomotion: Spring-mass vs. poly-articulated models

The human is often modeled as a Poly-Articulated Model (PAM) with rigid segments while some authors use a Spring Mass Model (SMM) for modeling locomotion. These two models are considered independent, and the objective of this study was to link them in order to enlighten the origin of the elasticity in locomotion.Using the characteristics of the two models, a theoretical relationship demonstrates that the variation of elastic energy of the SMM equals the variation of the internal kinetic energy minus internal forces work of the PAM. This theoretical relationship was experimentally investigated among 19 healthy participants walking and running on a treadmill.The results showed that the equality is verified except during the double support phase at 0.56 m s⁻¹, at high walking speeds (1.67 and 2.22 m s⁻¹) or during the aerial phase of running.The formal relationship showed that the global stiffness of the SMM is directly related to the work of the internal forces of the PAM, and thus, to the characteristics of the musculoskeletal system. It also showed the relevance of taking into account the participation of each joint in the global stiffness. Finally, the coordination of internal forces work to produce a global stiffness may be considered as a new criterion of movement optimization for clinical purposes or motion planning for humanoid robots.     

Contrast-enhanced FDG-PET/CT vs. SPIO-enhanced MRI vs. FDG-PET vs. CT in patients with liver metastases from colorectal cancer: a prospective study with intraoperative confirmation

BACKGROUND: The choice of imaging before liver surgery is debated regarding the use of magnetic resonance (MR) imaging, computed tomography (CT), and positron emission tomography (PET). No studies have compared contrast-enhanced PET/CT with superparamagnetic iron oxide (SPIO)-enhanced MR imaging. PURPOSE: To compare PET/CT with superparamagnetic iron oxide (SPIO)-enhanced MR imaging, PET, and CT in the detection of liver metastases (LM) and extrahepatic tumor from colorectal cancer (CRC). MATERIAL AND METHODS: Thirty-five patients with suspected LM underwent PET/CT with a contrast-enhanced CT protocol and SPIO-enhanced MR imaging. Readers independently analyzed images from MR imaging, PET/CT, and the CT part and PET part of the PET/CT study. Imaging findings were compared with surgical and histological findings. RESULTS: Lesion-by-lesion sensitivity and accuracy for liver lesions was 54% and 77% for PET alone, 66% and 83% for PET/CT, 82% and 82% for SPIO-enhanced MR imaging, and 89% and 77% for CT alone, respectively. CT and SPIO-enhanced MR imaging were less specific but significantly more sensitive than PET (P<0.0001). For extrahepatic tumor, sensitivity and specificity was 83% and 96% for PET/CT and 58% and 87% for CT, respectively. CONCLUSION: CT and SPIO-enhanced MR imaging are more sensitive but less specific than PET in the detection of LM. PET/CT can detect more patients with extrahepatic tumor than CT alone.