The association of parity with mortality outcomes among triplets

OBJECTIVE: The purpose of this study was to evaluate the association of parity with stillbirth and neonatal and infant death among triplets. STUDY DESIGN: This was a retrospective cohort study of 15,930 triplets who were delivered in the United States between 1995 and 1997. Infants of nulliparous mothers were compared with infants of multiparous mothers. Adjusted relative risks for death by parity were computed with the use of the generalized estimating equations framework. RESULTS: The likelihood for stillbirth (odds ratio, 3.40; 95% CI, 2.20-5.26) was significantly greater among nulliparous mothers. Neonatal (odds ratio, 1.17; 95% CI, 0.95-1.43) and infant mortality rates (odds ratio, 1.10; 95% CI, 0.92-1.32) were comparable, however. With an increase in parity, there was a consistent declining trend in the risk for stillbirth (P<.0001). CONCLUSION: Nulliparity more than triples the risk for intrauterine fetal death among triplets. This parity-related disparity underscores the need for care providers to be particularly concerned about triplet gestations among nulliparous mothers.     

Labor and delivery nurses: a survey of attitudes toward third-year medical students and their education

OBJECTIVE: Forty-six percent of third-year medical students at the University of Alberta rated labor and delivery nurses as a negative influence on their obstetrics and gynecology rotation. We hypothesized that the nurses would have mostly negative opinions toward students and their education. STUDY DESIGN: Labor and delivery nurses were surveyed with regard to their views on the following: (1) student learning objectives, (2) factors causing a patient to reject or accept a student, and (3) the role of the nurse in medical student education. RESULTS: Eighty-nine nurses ranked student tasks (objectives) as very appropriate, appropriate, neutral, inappropriate, and very inappropriate. History and physical examination, witnessing deliveries, assisting at deliveries, and following up women in labor were rated very appropriate or appropriate by more than 96% of nurses; 85% approved of students doing supervised deliveries. Nursing staff were equally divided in approving or disapproving of pelvic exams in labour and outpatient assessment by students. Artificial rupture of membranes, fetal scalp electrode application, and episiotomy repair were not approved of by more than 70% of nurses. The most important factors causing a patient to reject or accept a student were felt to be bedside manner and previous experience with a student, with least important being attractiveness, gender, and the nurse's opinion. Eighty-seven percent of nurses declared that one of their roles is to help students gain experience, but 71% said they would protect women from students with whom they were not comfortable. CONCLUSION: Labor and delivery nurses generally have a more positive attitude toward students and their learning than review of evaluations by the students would suggest. However, nurses have reservations about students performing technical procedures in the labor and delivery room. Creation of guidelines (objectives) with nursing input and better briefing of students with regard to nursing expectations may improve the student's experience.     

Visual neglect: occurrence and patterns in pilots in a simulated overnight flight

INTRODUCTION: Visual neglect is the unconscious inability to recognize or acknowledge some visual information in the presence of a structurally intact visual system, and was hypothesized to occur with less than 24 h of continuous wakefulness. Visual perception was evaluated in military pilots during a simulated overnight flight to explore for the possible occurrence of visual neglect. METHODS: There were eight military pilots (male, 31-52 yr of age, mean 37 yr) on flight status who were recruited to perform the primary task of flying a simulated 12.5 h overnight mission after a day of continuous wakefulness and the secondary task of responding to repeated 20 min presentations of single- and double-light stimuli displayed in random sequence at 15 degrees intervals across the cockpit instrument panel. In addition to the visual performance task, simulator shutdowns occurring when the tolerances of the simulator were exceeded were measured and simple reaction time on the psychomotor vigilance task was assessed. Total continuous wakefulness was 26.5 h. RESULTS: Combined performance on the visual perception task showed response omissions increasing at 19 h of continuous wakefulness. Patterns included omissions at all stimulus locations, of primarily peripherally located stimuli, and of one of two simultaneously presented stimuli. Simulator shutdowns began at 21.5 h of continuous wakefulness. Correlation of visual task response omissions with simulator shutdowns was r = 0.95, p < 0.0001. CONCLUSIONS: Significant neglect of visual stimuli occurred in pilots beginning at 19 h of continuous wakefulness in a simulated overnight fixed wing aircraft flight, preceded simulator shutdowns, and correlated at 0.95 with simulator shutdowns.     

Mechanical effect of posterior wire or half-pin configuration on stabilization utilizing a model of circular external fixation of the foot

BACKGROUND: Numerous studies have addressed biomechanical characteristics of circular external fixation of long bones. The objective of the present study was to evaluate stabilization of a simulated foot model using external fixation with either calcaneal tensioned stopper wires or half-pins. METHODS: Fixation configurations of the calcaneus included two parallel wires, two wires crossing at either 30 degrees or 45 degrees, a 4-mm- and 5-mm-diameter single half-pin, or two half-pins inserted at a cross-angle of either 45 degrees or 90 degrees. All frames were tested in axial compression, anteroposterior (AP) bending, and mediolateral (ML) bending. RESULTS: An increase in wire cross-angle improved the axial and AP bending stabilization but had no influence on ML bending. Utilization of a single calcaneal half-pin instead of two cross-wires resulted in a considerable reduction in ML bending stabilization. Frame configurations with two half-pins substantially improved axial and ML bending stabilization. Due to the medial location of the metatarsal wire stopper, an increase in half-pin cross-angle significantly improved ML bending stiffness under lateral foot loading. Under the medial foot loading, however, the half-pin cross-angle had no effect on ML bending stabilization. Replacement of cross-wires with two half-pins significantly improved the AP bending stiffness only when the half-pin cross-angle was reduced to 45 degrees. In all modes of two half-pin frame loading, the half-pin diameter had a substantial effect on foot stabilization. CONCLUSIONS: Although the wire cross-angle, half-pin cross-angle, and half-pin diameter affect the stability of foot circular external fixation, the influence of these mechanical parameters on foot stabilization is dependent on the mode and location of loading. CLINICAL RELEVANCE: The results of the present mechanical testing can be utilized as a useful guideline for the optimization of circular external fixation of the foot.     

The diagnostic accuracy of computed tomography in pediatric chronic rhinosinusitis

OBJECTIVE: To determine the accuracy of computed tomography (CT) in the diagnosis of pediatric chronic rhinosinusitis (CRS). SETTING: Multi-institutional prospective dual cohort study. METHODS: Two cohorts of children undergoing CT of the paranasal sinuses were prospectively evaluated. The first cohort consisted of children undergoing CT in preparation for endoscopic sinus surgery (diseased group). The second cohort consisted of children undergoing CT for nonsinusitis reasons (nondiseased control group). Sinus CT scans were scored according to the Lund-MacKay system. Diagnostic accuracy was quantified with the receiver operating characteristic curve. Sensitivity, specificity, and predictive value analyses were conducted. RESULTS: A total of 66 pediatric patients (mean age, 8 years) were studied in the diseased group and exhibited a mean Lund score of 10.4 (95% confidence interval, 9.2-11.5); 192 control patients (mean age, 9 years) exhibited a mean Lund score of 2.8 (95% confidence interval, 2.4-3.2). The area under the curve for the receiver operating characteristic was 0.923 (P<.001), indicating excellent diagnostic accuracy. Adopting a Lund score cutoff of 5 to represent true disease, the CT scan demonstrated a sensitivity and specificity of 86% and 85%, respectively. Lund scores of 2 or less have an excellent negative predictive value, whereas Lund scores of 5 or greater have an excellent positive predictive value (ie, strongly indicate true disease). CONCLUSIONS: The sinus CT scan demonstrates excellent diagnostic accuracy for the diagnosis of pediatric CRS, with excellent sensitivity and specificity. However, its predictive value depends substantially on the base rate prevalence of CRS in the population being evaluated.     

Health effects associated with recreational coastal water use: urban versus rural California

We compared rates of reported health symptoms among surfers in urban North Orange County (NOC) and rural Santa Cruz County (SCC), California, during 2 winters (1998 and 1999) to determine whether symptoms were associated with exposure to urban runoff. NOC participants reported almost twice as many symptoms as SCC participants during the 1998 winter. In both study years, risk increased across symptom categories by an average of 10% for each 2.5 hours of weekly water exposure. Our findings suggest that discharging untreated urban runoff onto public beaches can pose health risks.     

Retinal bipolar cells: contrast encoding for sinusoidal modulation and steps of luminance contrast

Contrast encoding for sinusoidal modulations of luminance contrast was investigated by intracellular recording in the intact salamander retina. In what appears to be the first study of this kind for vertebrate bipolar cells, responses of the central receptive-field mechanism of cone-driven cells to modulation of 3 Hz were analyzed quantitatively via both signal averaging and a Fast Fourier Transform (FFT) while the retina was light adapted to 20 cd/m2. Depolarizing and hyperpolarizing bipolar cells showed very similar encoding. Both responded with sinusoidal waveforms whose amplitude varied linearly with modulation depths ranging up to 7-8%. The slope of the modulation/response curve was very steep in this range. Thus, the contrast gain was high, reaching values of 6-7, and the half-maximal response was achieved at modulations of 9% or less. At modulations above approximately 15%, the responses typically showed strong compressive nonlinearity and the waveform was increasingly distorted. At maximum modulation, the higher harmonics of the FFT constituted about 30% of the amplitude of the fundamental. Measurements were also made for cones and horizontal cells. Both cell types showed predominantly linear responses and low contrast gain, in marked contrast to bipolar cells. These results suggest that the high contrast gain and strong nonlinearity of bipolar cells largely arise postsynaptic to cone transmitter release. Further experiments were performed to compare responses to contrast steps versus those to sinusoidal modulation. In the linear range, we show that the contrast gains of cones and horizontal cells are low and virtually identical for both steps and sinusoidal modulations. In bipolar cells, on the other hand, the contrast gain is about two times greater for steps than that for the 3-Hz sine waves. These results suggest that mechanisms intrinsic to bipolar cells act like a high-pass filter with a short time constant to selectively emphasize contrast transients over slower changes in contrast.