Obstetrical providers' preferred mode of delivery and attitude towards non-medically indicated caesarean sections: a cross-sectional study.

OBJECTIVE: To describe obstetrical providers' delivery preferences and attitudes towards caesarean section without medical indication, including on maternal request, and to examine the association between provider characteristics and preferences/attitudes. DESIGN: Cross-sectional study. SETTING: Two public and two private hospitals in Argentina. POPULATION: Obstetrician-gynaecologists and midwives who provide prenatal care and/or labour/delivery services. METHODS: Providers in hospitals with at least 1000 births per year completed a self-administered, anonymous survey. MAIN OUTCOME MEASURES: Provider delivery preference for low-risk women, perception of women's preferred delivery method, support for a woman's right to choose her delivery method and willingness to perform caesarean section on maternal request. RESULTS: 168 providers participated (89.8% coverage rate). Providers (93.2%) preferred a vaginal delivery for their patients in the absence of a medical indication for caesarean section. Whereas 74.4% of providers supported their patient's right to choose a delivery method in the absence of a medical indication for caesarean section and 66.7% would perform a caesarean section upon maternal request, only 30.4% would consider a non-medically indicated caesarean section for their own personal delivery or that of their partner. In multivariate adjusted analysis, providers in the private sector [odds ratio (OR) 4.70, 95% CI 1.19-18.62] and obstetrician-gynaecologists (OR 4.37, 95% CI 1.58-12.09) were more willing than either providers working in the public/both settings or midwives to perform a caesarean section on maternal request. CONCLUSIONS: Despite the ethical debate surrounding non-medically indicated caesarean sections, we observe very high levels of support, especially by providers in the private sector and obstetrician-gynaecologists, as aligned with the high caesarean section rates in Argentina. TWEETABLE ABSTRACT: Non-medically indicated c-section? 74% of sampled Argentine OB providers support women's right to choose.

The efficiency of an asynchronous flight muscle from a beetle.

Mechanical power output and metabolic power input were measured from an asynchronous flight muscle, the basalar muscle of the beetle Cotinus mutabilis. Mechanical power output was determined using the work loop technique and metabolic power input by monitoring CO(2) production or both CO(2) production and O(2) consumption. At 35 degrees C, and with conditions that maximized power output (60 Hz sinusoidal strain, optimal muscle length and strain amplitude, 60 Hz stimulation frequency), the peak mechanical power output during a 10 s burst was approximately 140 W kg(-1), the respiratory coefficient 0.83 and the muscle efficiency 14-16 %. The stimulus intensity used was the minimal required to achieve a maximal isometric tetanus. Increasing or decreasing the stimulus intensity from this level changed mechanical power output but not efficiency, indicating that the efficiency measurements were not contaminated by excitation of muscles adjacent to that from which the mechanical recordings were made. The CO(2) produced during an isometric tetanus was approximately half that during a bout of similar stimulation but with imposed sinusoidal strain and work output, suggesting that up to 50 % of the energy input may go to muscle activation costs. Reducing the stimulus frequency to 30 Hz from its usual value of 60 Hz reduced mechanical power output but had no significant effect on efficiency. Increasing the frequency of the sinusoidal strain from 60 to 90 Hz reduced power output but not CO(2) consumption; hence, there was a decline in efficiency. The respiratory coefficient was the same for 10 s and 30 s bursts of activity, suggesting that there was no major change in the fuel used over this time range. The mass-specific mechanical power output and the efficiency of the beetle muscle were each 2-3 times greater than values measured in previous studies, using similar techniques, from locust flight muscles, which are synchronous muscles. These results support the hypothesis that asynchronous flight muscles have evolved in several major insect taxa because they can provide greater power output and are more efficient than are synchronous muscles for operation at the high frequencies of insect flight.

Power output by an asynchronous flight muscle from a beetle.

The basalar muscle of the beetle Cotinus mutabilis is a large, fibrillar flight muscle composed of approximately 90 fibers. The paired basalars together make up approximately one-third of the mass of the power muscles of flight. Changes in twitch force with changing stimulus intensity indicated that a basalar muscle is innervated by at least five excitatory axons and at least one inhibitory axon. The muscle is an asynchronous muscle; during normal oscillatory operation there is not a 1:1 relationship between muscle action potentials and contractions. During tethered flight, the wing-stroke frequency was approximately 80 Hz, and the action potential frequency in individual motor units was approximately 20 Hz. As in other asynchronous muscles that have been examined, the basalar is characterized by high passive tension, low tetanic force and long twitch duration. Mechanical power output from the basalar muscle during imposed, sinusoidal strain was measured by the work-loop technique. Work output varied with strain amplitude, strain frequency, the muscle length upon which the strain was superimposed, muscle temperature and stimulation frequency. When other variables were at optimal values, the optimal strain for work per cycle was approximately 5%, the optimal frequency for work per cycle approximately 50 Hz and the optimal frequency for mechanical power output 60-80 Hz. Optimal strain decreased with increasing cycle frequency and increased with muscle temperature. The curve relating work output and strain was narrow. At frequencies approximating those of flight, the width of the work versus strain curve, measured at half-maximal work, was 5% of the resting muscle length. The optimal muscle length for work output was shorter than that at which twitch and tetanic tension were maximal. Optimal muscle length decreased with increasing strain. The curve relating work output and muscle length, like that for work versus strain, was narrow, with a half-width of approximately 3 % at the normal flight frequency. Increasing the frequency with which the muscle was stimulated increased power output up to a plateau, reached at approximately 100 Hz stimulation frequency (at 35 degrees C). The low lift generated by animals during tethered flight is consistent with the low frequency of muscle action potentials in motor units of the wing muscles. The optimal oscillatory frequency for work per cycle increased with muscle temperature over the temperature range tested (25-40 degrees C). When cycle frequency was held constant, the work per cycle rose to an optimum with increasing temperature and then declined. We propose that there is a temperature optimum for work output because increasing temperature increases the shortening velocity of the muscle, which increases the rate of positive work output during shortening, but also decreases the durations of the stretch activation and shortening deactivation that underlie positive work output, the effect of temperature on shortening velocity being dominant at lower temperatures and the effect of temperature on the time course of activation and deactivation being dominant at higher temperatures. The average wing-stroke frequency during free flight was 94 Hz, and the thoracic temperature was 35 degrees C. The mechanical power output at the measured values of wing-stroke frequency and thoracic temperature during flight, and at optimal muscle length and strain, averaged 127 W kg(-1)muscle, with a maximum value of 200 W kg(-1). The power output from this asynchronous flight muscle was approximately twice that measured with similar techniques from synchronous flight muscle of insects, supporting the hypothesis that asynchronous operation has been favored by evolution in flight systems of different insect groups because it allows greater power output at the high contraction frequencies of flight.

Asynchronous muscle: a primer.

The asynchronous muscles of insects are characterized by asynchrony between muscle electrical and mechanical activity, a fibrillar organization with poorly developed sarcoplasmic reticulum, a slow time course of isometric contraction, low isometric force, high passive stiffness and delayed stretch activation and shortening deactivation. These properties are illustrated by comparing an asynchronous muscle, the basalar flight muscle of the beetle Cotinus mutabilis, with synchronous wing muscles from the locust, Schistocerca americana. Because of delayed stretch activation and shortening deactivation, a tetanically stimulated beetle muscle can do work when subjected to repetitive lengthening and shortening. The synchronous locust muscle, subjected to similar stimulation and length change, absorbs rather than produces work.

Relationship between short-range stiffness and yielding in type-identified, chemically skinned muscle fibers from the cat triceps surae muscles.

1. Transient, stretch-evoked force responses of chemically skinned muscle fibers from the cat hindlimb were investigated. The purpose of these experiments was to determine the exent to which short-range stiffness, the apparent stiffness exerted by the fiber over the first 0.5% of length change, is higher in type I than type II muscle fibers. Fibers were obtained from soleus and vastus intermedius muscles, which contain predominantly type I fibers, the LGm, a compartment of the lateral gastrocnemius muscle that contains predominantly type II fibers, and LG3, a compartment of mixed type. 2. Beyond a short range of approximately 1% of muscle length during a 0.5 muscle length/s (ML/s) stretch, most fibers exhibited an abrupt decrease in apparent stiffness or yield. Fibers from the muscles containing predominantly type S (slow twitch, or type I) fibers, soleus and vastus intermedius, exhibited such a pronounced decline in apparent stiffness that force declined as well during continued stretch. Most of the fibers from the LG3 compartment could be divided into two distinct groups depending upon whether or not they showed a force yield at the stretch velocity of 0.5 ML/s. 3. The short-range stiffness measured over the first 0.5% of stretch was greater for fibers showing force yield than for those that did not at matched initial forces and normalized stretch amplitudes. This result is consistent with the hypothesis that the same mechanism that endows the fiber with high short-range stiffness is also responsible for a greater extent of yielding. 4. Fibers from soleus were found to exhibit a force yield over a 200-fold range of velocities (0.01-2 ML/s). In contrast, most fibers from the LGm compartment showed only an increase in extent of yield with stretch velocity. Some of these fibers eventually yielded in force, but only when they were stretched at velocities > 2 ML/s. The proposed relationship between high short-range stiffness and yielding was supported by the finding that short-range stiffness increased sharply in the range of velocities where the fiber showed the greatest increase in extent of yield. 5. After the physiological experiments, fibers were subjected to SDS gel electrophoresis. Two distinct patterns of bands in the low molecular weight range were found to correspond to the two types that were identified on the basis of their dynamic mechanical properties. Fibers that did not yield at 0.5 ML/s showed a band pattern very similar to that of rabbit psoas (type II) fibers. 6. These results support the hypothesis that type I fibers are specialized in presenting a high short-range stiffness for effective postural control in advance of reflex mechanisms and that this property results from intrinsic properties of the fiber and is not due to differences in the dimensions of type I and II fibers. Yielding serves to protect the fiber from damaging levels of force during lengthening contractions. The importance of these transient properties to the mechanical behavior of muscle during ongoing movements is suggested by the observation that high stiffness followed by yielding is repeated with little alteration during successive stretches.

UnCover: the article access solution.

The current climate for academic libraries is such that traditional collection development philosophies are being examined anew. The rising cost of journals, coupled with steady or declining budgets, has necessitated a review of the means for providing access to information at the local level. Where once the local collection was all-important, the focus now has shifted in other directions. As Leach describes it, libraries will begin to shift collection development funds to document delivery services. Instead of purchasing resources "just in case," the new paradigm may be purchasing information "just in time". Anticipating this shift and taking advantage of existing technologies, the UnCover Company has developed a service that, although relatively new, has been widely discussed.

Preselecting literature for routine delivery to physicians in a community hospital-based patient care related reading program.

Health sciences librarians have been actively responding to the changing information needs of users by extending services which involve the selection of literature in response to specific requests from health care personnel. A further development is Patient Care Related Reading (PCRR), a hospital-based program of continuing medical education in which the librarian actively participates in the preselection, packaging, and routine delivery of literature for use by physicians caring for patients with certain clinical disorders. Criteria for selection of literature packet topics were developed jointly by librarians and physicians at their own hospitals. Librarians compiled bibliographic material, reviewed articles, and prepared preliminary packets. Physicians reviewed these packets and made suggestions for each article. Librarians then prepared final packets following reviewers' recommendations and distributed them as a routine procedure to all physicians caring for patients with a diagnosis corresponding to prepared topics. Librarians were notified of patients with PCRR clinical problems by admitting office personnel, floor nurses, nursing supervisors, utilization review, and Professional Standards Review Organization personnel as a part of their usual activities. Packets are used by physicians to add to their fund of knowledge, and for review and teaching purposes. PCRR has provided increased visibility of the library and its many services. Recognition of the librarian's role in the program reinforces the concept of the community hospital library as a service-oriented entity, and helps to establish the library as an active partner in the development and implementation of hospital-based continuing education programs.

Diagnosis of intrauterine growth retardation by a simple clinical method: measurement of uterine height.

Generally there is a tendency to underrate the value of uterine height in the diagnosis of intrauterine growth retardation (IUGR). This fact is probably due to the lack of standard normal values for this measurement. In a group of 298 healthy pregnant women, the 10th, 50th, and 90th percentile were calculated by week of amenorrhea. Uterine height was measured with a nonelastic measuring tape, from the symphysis pubis to the fundus uteri. With the use of these standard values the predictive value of the method was established. Of 44 neonates with low birth weight for gestational age, 38 had a uterine height below the 10th percentile (sensitivity 86%). Six cases of IUGR were not diagnosed by this method. Of 95 neonates with adequate birth weight, 85 had uterine values above the 10th percentile (specificity 90%). Ten (10%) of these were predicted as low birth weight but were born with adequate weight. The uterine height measurement is shown to be a very good method for detecting IUGR. It can be used as a screening test to detect impairment in fetal growth and to make early referral of those pregnancies.