Nonlocal effect of plasma resonances on the electron energy-distribution function in microwave plasma columns.

Spatially resolved trace rare gases optical emission spectroscopy was used to analyze the electron energy-distribution function (EEDF) in low-pressure argon plasma columns sustained by surface waves. At frequencies >1 GHz, in the microwave-sustained region, the EEDF departs from a Maxwellian, characterized by a depletion of low-energy electrons and a high-energy tail, whereas in the field-free zone, the EEDF is Maxwellian. Abnormal behavior of the EEDF results from the acceleration of low-energy electrons due to the conversion of surface waves into volume plasmons at the resonance point where the plasma frequency equals the wave frequency and their absorption by either collisional or Landau damping.

What is the value of ultrasound soft tissue measurements in the prediction of abnormal fetal growth?

Abnormal fetal growth increases the complications of pregnancy not only for the baby but also for the mother. Growth abnormalities also have lifelong consequences. These babies are at increased risk of insulin resistance, diabetes and hypertension later in life. It is important to identify these babies antenatally to optimise their clinical care. Although used extensively antenatally to monitor fetal growth, ultrasound has its limitations. Despite the use of more than 50 different formulae to estimate fetal weight, their performance has been poor at the extremes of fetal weight. Over the past 20 years there has been emerging interest in studying fetal soft tissue measurements to improve detection of growth abnormalities. This review paper outlines the value of soft tissue measurements in identifying fetal growth abnormalities, in estimating fetal weight and in managing diabetes mellitus in pregnancy.

Plasma-surface reactions at a spinning wall.

We report a new method for studying surface reactions and kinetics at moderately high pressures (<10 Torr) in near real time. A cylindrical substrate in a reactor wall is rotated at up to 200,000 rpm, allowing the surface to be periodically exposed to a reactive environment and then analyzed by a triple-differentially pumped mass spectrometer in as little as 150 micros thereafter. We used this method to study oxygen plasma reactions on anodized aluminum. When the substrate is spun with the plasma on, a large increase in O2 signal at m/e = 32 is observed with increasing rotation frequency, due to O atoms that impinge and stick on the surface when it is in the plasma, and then recombine over the approximately 0.7 to 40 ms period probed by changing the rotation frequency. Simulations of O2 signal versus rotation frequency indicate a wide range of recombination rate constants, ascribed to a range of O-binding energies.

Recombination reactions of oxygen atoms on an anodized aluminum plasma reactor wall, studied by a spinning wall method.

We have studied the recombination of O atoms on an anodized Al surface in an oxygen plasma, using a new "spinning wall" technique. With this method, a cylindrical section of the wall of the plasma reactor is rotated and the surface is periodically exposed to an oxygen plasma and then to a differentially pumped mass spectrometer (MS). By varying the substrate rotation frequency (r), we vary the reaction time (t(r)), that is, the time between exposure of the surface to O atoms in the plasma and MS detection of desorbing O(2) (t(r) = 1/2r). As t(r) is increased from 0.7 to 40 ms, the O(2) desorption signal decreases by a factor of 2 for an O-atom flux of 1 x 10(16) cm(-2) s(-1) and by a factor of 6 when the O flux is 1 x 10(17) cm(-2) s(-1). The O(2) signal decay is highly nonexponential, slowing at longer times and reaching zero signal as r --> 0. A model of O-atom recombination is compared with these time-dependent results. The model assumes adsorption occurs at surface sites with a range of binding energies. O can detach from these sites, become mobile, and diffuse along the surface. This leads to desorption of O, reattachment at free adsorption sites, and recombination to form O(2) that promptly desorbs. With several adjustable parameters, the model reproduces the observed shapes of the O(2) desorption decay curves and the lack of detectable desorption of O and predicts a high O-atom recombination coefficient on anodized aluminum.

Health care-seeking for menopausal problems.

OBJECTIVES: To determine the rate and timing of medical consultations for menopausal problems during the menopausal transition and to identify baseline and prospective variables associated with these consultations. METHODS: This was a 9-year community-based study with annual interviews of 438 Australian-born women who at baseline were aged 45-55 years, had menstruated in the previous 3 months and were not using hormone therapy. RESULTS: In total, 387 women completed the 9-year study, of whom 86% consulted a doctor about menopausal problems, with an annual mean of 31%. Of the women, 212 experienced a natural menopause. The prevalence of consultations regarding menopausal problems was a maximum about 2.5 years before the final menstrual period (FMP). The time of greatest prevalence of reporting bothersome hot flushes was 2.1 years after the FMP. There was no significant relationship between number of symptoms reported and time to/from the FMP. Multiple regression analysis found that an increased number of consultations for menopausal problems was associated with the baseline variables: vasomotor symptoms (p < 0.005), rating one's health as 'worse than most' (p < 0.005) and taking two or more non-prescription medications (p < 0.05); and the follow-up variables: dysphoric symptoms (p < 0.05), vasomotor symptoms (p < 0.005) and hormone therapy use (p < 0.001). CONCLUSION: Nearly one-third of women will consult a doctor annually during the years of the menopausal transition. Those who are more symptomatic with mood or vasomotor symptoms consult doctors more often and are more likely to use hormone replacement therapy.

Effect of second vaginal delivery on anorectal physiology and faecal continence: a prospective study.

BACKGROUND: Because obstetric injury to the anal sphincters may be occult, and because the mechanism of injury differs between first and subsequent deliveries, we prospectively assessed the effects of first and second vaginal deliveries on anal physiology and continence. METHODS: We undertook a prospective observational study of 59 previously nulliparous women through two successive vaginal deliveries by means of a bowel-function questionnaire, and an anorectal-physiology assessment, both antepartum and 6-12 weeks post partum. FINDINGS: 13 (22%) women reported altered faecal continence after their first vaginal delivery: eight had persistent symptoms during their second pregnancy, of whom seven deteriorated after the second delivery; five regained continence before their second pregnancy, but two became incontinent again after the second delivery. Five women developed incontinence for the first time after their second vaginal delivery, of whom three had occult primiparous sphincter injury. 20 (34%) women, seven of whom had no symptoms, had anal-sphincter injury as a result of their first delivery, but only two new injuries occurred after the second vaginal delivery (p=0.013). Although pudendal neuropathy was no more common after the second than after the first vaginal delivery (15 vs 19%, p=0.8), pudendal-nerve latency was longer after the second delivery (p=0.02). INTERPRETATION: Primiparous women with persistent symptoms of altered faecal continence experience deterioration after a second vaginal delivery. Women with transient faecal incontinence or occult anal-sphincter injury after their first vaginal delivery are at high risk of faecal incontinence after a second vaginal delivery. The risk of mechanical anal sphincter injury is greatest after the first delivery.

Management of blunt splenic trauma in patients older than 55 years. Southern Connecticut Regional Trauma Quality Assurance Committee.

BACKGROUND: Many experts have suggested that blunt splenic trauma in patients older than 55 years should not be managed by observation because of supposed increased fragility of the spleen and decreased physiologic reserve in elderly patients. We sought to determine the outcome of nonoperative management of blunt splenic trauma in patients older than 55 years. METHODS: For the years 1994 through 1996, data for patients with splenic injury older than 55 years from seven trauma centers in a single state were reviewed. RESULTS: Blunt splenic trauma occurred in 41 patients older than 55 years. Eight patients were excluded from further analysis because of death from massive associated injuries within 24 hours of admission. The remaining 33 patients (mean age, 72+/-10 years) were divided into two groups: immediate exploration (10 patients) and observation (23 patients). Observation of blunt splenic injury failed in 4 of 23 patients (17%). No patient deaths were related to the method of management of the splenic injury. CONCLUSIONS: Observation of the elderly patient with blunt splenic trauma has an acceptable failure rate of 17%.

Trace rare gases optical emission spectroscopy: nonintrusive method for measuring electron temperatures in low-pressure, low-temperature plasmas.

Trace rare gases optical emission spectroscopy (TRG-OES) is a new, nonintrusive method for determining electron temperatures (T(e)) and, under some conditions, estimating electron densities (n(e)) in low-temperature, low-pressure plasmas. The method is based on a comparison of atomic emission intensities from trace amounts of rare gases (an equimixture of He, Ne, Ar, Kr, and Xe) added to the plasma, with intensities calculated from a model. For Maxwellian electron energy distribution functions (EEDFs), T(e) is determined from the best fit of theory to the experimental measurements. For non-Maxwellian EEDFs, T(e) derived from the best fit describes the high-energy tail of the EEDF. This method was reported previously, and was further developed and successfully applied to several laboratory and commercial plasma reactors. It has also been used in investigations of correlations between high-T(e) and plasma-induced damage to thin gate oxide layers. In this paper, we provide a refined mechanism for the method and include a detailed description of the generation of emission from the Paschen 2p manifold of rare gases both from the ground state and through metastable states, a theoretical model to calculate the number density of metastables (n(m)) of the rare gases, a practical procedure to compute T(e) from the ratios of experimental-to-theoretical intensity ratios, a way to determine the electron density (n(e)), a discussion of the range of sensitivity of TRG-OES to the EEDF, and an estimate of the accuracy of T(e). The values of T(e) obtained by TRG-OES in a transformer-coupled plasma reactor are compared with those obtained with a Langmuir probe for a wide range of pressures and powers. The differences in T(e) from the two methods are explained in terms of the EEDF dependence on pressure.

Obstetric events leading to anal sphincter damage.

OBJECTIVE: To identify the obstetric factors relating to anal sphincter injury at first vaginal delivery by prospective cohort study of primiparous women. METHODS: We compared the results of a bowel function questionnaire and anal vector manometry before and 6 weeks after delivery in 184 primiparous women. Postpartum, pudendal nerve conduction latency was measured in all women, and anal endosonography was performed in 81 with altered fecal continence or abnormal physiology. RESULTS: Sixteen (9%) women, none of whom had altered fecal continence, were delivered by cesarean. After vaginal delivery, 42 of 168 (25%) women had impairment of fecal continence and 76 of 168 (45%) women had abnormal anal physiology. Instrumental vaginal delivery was associated with an 8.1-fold (95% confidence interval [CI] 2.7, 24.0; P < .001) risk of anal sphincter injury and a 7.2-fold (95% CI 2.8, 18.6; P < .001) risk of symptoms. Duration of the second stage of labor beyond 60 minutes led to a 1.7-fold (95% CI 1.14, 2.48; P;< .01) risk of anal sphincter injury and a 1.6-fold (95% CI 1.03, 2.6, P = .01) risk of symptoms. Epidural analgesia, used in 58% of vaginal deliveries, prolonged the second stage of labor (P = .004; odds ratio [OR] 7.7; 95% CI 4.0, 14.7) and was associated with increased risk of sphincter injury (P = .02; OR 2.1; 95% CI 1.1, 4.0) and of symptoms (P = .02; OR 2.0; 95% CI 1.1, 3.7). CONCLUSION: Instrumental delivery and a second stage of labor prolonged by epidural analgesia are the obstetric factors that pose the greatest risk of injury to the anal sphincter mechanism in primiparous vaginal delivery.

Cesarean delivery and anal sphincter injury.

OBJECTIVE: Cesarean delivery has been thought to prevent all obstetric anal sphincter damage. The objective of this study was to determine the relationship between the timing of cesarean during primiparous delivery and injury to the anal sphincter mechanism. METHODS: A prospective observational study was conducted, using a continence questionnaire and anorectal physiology assessment before and six weeks after primiparous delivery. A cohort of 234 women were recruited from the antenatal clinics at the National Maternity Hospital, Dublin. Thirty-four women delivered subsequently by cesarean, and 200 women by spontaneous vaginal delivery. RESULTS: Thirty-four women underwent cesarean delivery without attempted vaginal delivery: eight prior to labor and 26 during labor, 17 in early labor (cervical dilatation less than 8 cm) and 9 in late labor (dilatation greater than 8 cm). No woman delivered by cesarean had altered fecal continence postpartum. Anorectal physiology was unaltered in women delivered by elective cesarean or cesarean in early labor. Pudendal nerve terminal motor latency was prolonged, anal squeeze pressure increment reduced, but vector symmetry index was unchanged in women delivered by cesarean delivery late in labor, indicating neurologic injury to the anal sphincter mechanism. CONCLUSION: Cesarean delivery performed in late labor, even in the absence of attempted vaginal delivery, does not protect the anal sphincter mechanism.

Postpartum fecal incontinence is more common in women with irritable bowel syndrome.

PURPOSE: Anal sphincter damage can occur during vaginal delivery and may lead to impairment of fecal continence. The aim of this study was to determine the influence of irritable bowel syndrome on symptoms of fecal incontinence following first vaginal delivery. METHODS: A prospective, observational study was performed before delivery, six weeks, and six months following delivery in primiparous women. A bowel function questionnaire was completed, and anal vector manometry, mucosal electrosensitivity, pudendal nerve terminal motor latency, and anal endosonography were performed. A total of 208 women were assessed before and after delivery, and 104 primigravid women were studied after delivery only. A total of 34 of 312 (11 percent) had an existing diagnosis of irritable bowel syndrome. RESULTS: The prevalence of abnormal manometry or endosonography was similar in women with and without irritable bowel syndrome. However, six weeks after delivery, women with irritable bowel syndrome had a higher incidence of defecatory urgency (64 percent) and loss of control of flatus (35 percent) compared with those without (urgency, 10 percent, P < 0.001; flatus, 13 percent, P = 0.007). The incidence of frank fecal incontinence was similar in the two groups. Women with IBS had increased mucosal sensitivity to electrical stimulation of the upper anal canal both before and after delivery. CONCLUSION: Women with IBS are more likely to experience subjective alteration of fecal continence postpartum compared with the healthy primigravid population, but they are not at increased risk of anal sphincter injury.

The influence of oestrogen replacement on faecal incontinence in postmenopausal women.

OBJECTIVE: To assess the value of hormone replacement therapy (HRT) in postmenopausal women with faecal incontinence. DESIGN: Prospective observational study using a bowel function questionnaire and anorectal physiological testing before and after six months of standard oestrogen hormone replacement therapy. SETTING: Menopause and colorectal clinics of two university teaching hospitals. PARTICIPANTS: Twenty postmenopausal women (mean age 61 years) with demonstrable faecal incontinence (mean duration 6.1 years) previously untreated with HRT. MAIN OUTCOME MEASURES: Improvement in symptoms and objective alteration in anorectal physiology tests. RESULTS: All women had significant symptoms of anorectal dysfunction before treatment, whereas 5/20 (25%) were asymptomatic after six months of HRT, and a further 13/20 (65%) were symptomatically improved in terms of flatus control, urgency, and faecal staining. There was no change in bowel frequency or stool consistency following HRT, but social activity was considerably improved. Anal resting pressures and voluntary squeeze increments were significantly increased following oestrogen therapy, although no differences in anal canal vector symmetry index were observed. Insignificant changes occurred in threshold volume of rectal sensation and volume of defaecatory urge, but there was a significant change in maximum tolerated rectal volume after six months. Neither anal canal electrosensitivity nor pudendal nerve terminal motor latency was altered following HRT. Seven of the 20 women (35%) had an identifiable anal sphincter defect on anal endosonography. Statistical analysis, however, showed no significant difference in outcome in this group compared with those with an intact anal sphincter. A larger population sample may demonstrate this. CONCLUSION: This observational study has shown a possible benefit of oestrogen replacement in postmenopausal women with symptoms of impaired faecal continence. A prospective randomised controlled trial is now advisable to test this hypothesis.

Anal canal pressures are low in women with postpartum anal fissure.

BACKGROUND: Anal sphincter hypertenia is commonly thought to underlie development of anal fissure, yet anal fissure is particularly common after childbirth, a time when anal canal pressure may be reduced. This paradox was investigated by a prospective study of the effect of parturition on the pelvic floor. METHODS: Anal manometry was performed 6 weeks before and after delivery in 209 primigravid women with no pre-existing history of anorectal disease. Postpartum studies only were performed on a further 104 primiparae. Anal fissure was diagnosed by history and direct examination. RESULTS: Some 29 women (9 per cent) developed postpartum anal fissure. Antepartum anal canal resting and squeeze pressures were similar in women who did and those who did not develop fissure. Resting and squeeze anal canal pressures decreased post partum in both groups. Postpartum constipation was more common in those with fissure (62 per cent) than in those without (29 per cent) (chi 2 = 10.6, 1 d.f., P < 0.01). The mode of delivery or use of epidural analgesia did not affect the incidence of fissure. CONCLUSION: Postpartum anal fissure is associated with reduced anal canal pressures, and surgical interference with the anal sphincter mechanism should be avoided.

Social support and its relationship to immunization status in preschool children.

Many children are at risk for developing serious and costly health problems because they are not adequately immunized. This descriptive correlational study explored the relationship between social support, parental knowledge of vaccine-preventable diseases, and the immunization status of preschool children. A convenience sample of 153 parents and guardians of children aged 6 to 24 months completed Procidano and Heller's Perceived Social Support Scales, a questionnaire on immunization knowledge, and a demographics questionnaire. Data indicating completeness of immunizations were obtained from the children's health records. Point-biserial statistical analysis revealed a positive relationship between immunization status and social support (r = .29; p = .0003). This finding supports those of past studies that identified a positive relationship between social support and preventive health practices. No relationship was found between immunization status and parental knowledge of vaccine-preventable diseases. Assessment of social support can assist nurses in identifying children at risk for incomplete immunizations and in isolating potential reasons for the deficiency.

Endosonographic assessment of postpartum anal sphincter injury using a 120 degree sector scanner.

Obstetric injury is the principal cause of faecal incontinence in women. We describe use of a 120 degrees sector ultrasound probe to assess integrity of the anal sphincters in primigravid women. Eighty-eight women were successfully studied 6 weeks following vaginal delivery. Anal vector manometry and pudendal nerve studies were abnormal in 54 (61%), of whom 41 (71%) were symptomatic (urgency of defaecation, incontinence to flatus or faeces). The sonographic pattern of the anal sphincters described with a 360 degrees probe was reproduced. Forty-eight abnormal scans were reported by two radiologists with a kappa statistic of 0.65. Sphincter defects were found in 11 asymptomatic women. We conclude that anal endosonography has an important role screening for and diagnosis of postpartum anal sphincter defects. Use of a 120 degrees sector ultrasound probe may prove a cost-effective means of increasing the availability of this technique.

DES clinic--the first six months.

In October 1990 a DES (Diethylstilbestrol) clinic was established at the National Maternity Hospital, Dublin. We describe the results of the first six months of the clinic. During this time, 172 inquiries were received; 95 women were seen at the clinic, 16 were deemed to be DES--exposed and eight were classified as possibly DES exposed. Classical cervicovaginal signs of DES exposure were noted in 15 women, a further eight women showed cervical epithelial abnormalities at colposcopy, the history of in utero DES exposure was confirmed in eight cases. No cases of cervical intraepithelial neoplasia or vaginal clear-cell adenocarcinoma were detected. Pregnancy related problems possibly attributable to DES exposure were documented in six women.