Performance of six types of oxygen delivery devices at varying respiratory rates.

The administration of a known concentration of oxygen is an important part of routine care of the sick patient. Many devices are currently available. The actual concentration of oxygen that can be delivered by these devices can be affected by several factors, both from the patient as well as the device itself. Measuring the F(i)o(2) delivered to the lungs in vivo can be both difficult and potentially uncomfortable for the subjects. We constructed a model using a resuscitation manikin, a ventilator and a set of bellows to simulate ventilation. With this model we tested a series of devices - variable performance, fixed performance and high flow - at two fixed tidal volumes. The respiratory rate was increased and its effect on the oxygen concentration assessed. Variable performance systems such as the Hudson mask deliver a significantly reduced oxygen concentration at high respiratory rates. Fixed performance systems delivering 24-40% oxygen deliver appropriate oxygen concentrations across the range of respiratory rates, whereas those delivering 60% show a reduction in performance. High flow systems show no failure of performance at increased respiratory rates.

A prospective follow up study of women with colposcopically unconfirmed positive cervical smears.

OBJECTIVE: To examine a cohort of women with positive cervical smears, but negative colposcopy, in order to ascertain whether there is a subsequent difference in the incidence of squamous dyskaryosis and cervical intraepithelial neoplasia when compared with a control group. DESIGN: Prospective follow up study. SETTING: Colposcopy clinics, antenatal clinics, GP surgeries. METHODS: A study group of 255 women with reported abnormal cervical smears but negative colposcopy was subdivided into three groups according to referral smears suggesting high grade dyskaryosis (n = 34), mild dyskaryosis (n = 120) and borderline changes (n = 101). They were followed for at least five years and were compared with a control group of 726 women followed up after a negative smear, using the first and worst follow up smears over a five year recall period. MAIN OUTCOME MEASURES: Incidence of subsequent cervical cytological and histological abnormalities. RESULTS: The control group had a similar incidence of squamous dyskaryosis as that expected in the screening population. Forty-six per cent of the study group with colposcopically unconfirmed ('false positive') cervical smears subsequently had abnormal smears. When the three groups were compared with controls using a chi2 test, their incidence of abnormal smears was significantly increased. Cervical intrepithelial neoplasia was found in 19% of the study group, and in 3% of the control group (P < 0.0001). CONCLUSIONS: The analysis demonstrates that women with so-called 'false positive' smears defined by negative colposcopy have an increased risk of subsequent abnormal smears and cervical intrepithelial neoplasia, suggesting that lesions may have been missed on colposcopy. However, in a significant proportion of women, further abnormalities were not detected during the follow up period, indicating that there may be other causes for positive smears and negative colposcopy.

Productive use of IT in support of FM (facilities management) solutions.

Drawing on the author's personal experience within the UK National Health Service, outlines at the macro level what information is needed, and why, in facilities management. Suggests that top-level data gathering is a priority, describes the processes required, and finally considers the advantages of sharing information with competitors and others.

A retrospective analysis of 94 patients with CIN and false negative cervical smears taken at colposcopy.

This report investigates the reasons for false negative cervical cytology in 94 out of 630 patients (15%) in whom cervical intraepithelial neoplasia (CIN) was diagnosed on colposcopically directed biopsy. Cervical smears were taken immediately before biopsy and the cases with false negative cytology were compared with those whose cytology was abnormal. Patients with false negative cytology were more likely to have been younger (P < 0.01), to have had fewer pregnancies (P < 0.001), to have had a less severe grade of dyskaryosis on their referral smear (P < 0.001), to have had no endocervical cells on the smear (P < 0.05), to have had a less severe grade of CIN on biopsy (P < 0.001), to have had no punctation visible at colposcopy (P < 0.01), and to have had no mosaic pattern seen at colposcopy (P < 0.05). We found no effect attributable to the patient's menstrual history, the interval between referral smear and colposcopy clinic visit, the smear taker or the type of spatula used to take the smear.

Relationship between serum immunoglobulin G and alpha-fetoprotein levels during human pregnancy.

The immunoregulatory processes operating during pregnancy that allow the survival of the semiallogeneic conceptus are at present far from understood. alpha-fetoprotein (AFP) is a biological component of the body produced in high amounts during pregnancy mainly by the fetal liver, and in certain clinical pathological states. The biological function of AFP is still unknown, but some investigators postulate an immunosuppressive role for the protein during pregnancy. In this study, serum immunoglobulin G, M and A levels of 101 gravidas at different stages of gestation (26 from 11-14 weeks, 37 from 32-34 weeks and finally 38 from 38-40 weeks) were determined and compared to 57 age matched nonpregnant females. Before being included in the study, patients were checked for various conditions which potentially alter immunoglobulin and AFP serum levels. Maternal serum samples showed a significant decreased concentration of immunoglobulin G (IgG) as compared to non-pregnancy serum samples (table I). AFP levels were also quantitated in the pregnancy sera and correlated with immunoglobulins levels. A strongly negative correlation between AFP and IgG was found throughout gestation (table II). When gestational age was fixed and the partial coefficients of correlation calculated, the inverse correlation persisted. In addition, the relationship between AFP and IgG at the various periods of gestation (11-14 weeks, 32-34 weeks and 38-40 weeks), calculated in order to detect where the association was stronger, revealed significant and uniform negative correlations (table III).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of mitogen and allogeneic stimulated lymphocyte growth by human amniotic fluid: lack of correlation between alpha-fetoprotein level and in vitro immunosuppression.

The influence of human amniotic fluid from women at 16-18 wk gestation on the in vitro proliferation of human peripheral lymphocytes stimulated with various mitogens (PHA, Con A and PWM) and with allogeneic cells in the one- and two-way mixed lymphocyte reaction (MLR) was studied. It was seen that amniotic fluid inhibits nonspecifically the responsiveness of the various subpopulations of cells induced to proliferate. It was also demonstrated that the suppression depends on the concentration of the immunosuppressive agent(s), since diluted amniotic fluids showed less inhibitory capacity. In order to detect a possible immune action for alpha-fetoprotein (AFP), the levels of the protein in the amniotic fluid supplemented cultures were correlated with the inhibitory properties of the fluids. No correlation was encountered, indicating that AFP is not mainly responsible for the in vitro immunosuppressive properties of human amniotic fluid on the in vitro test of cell-mediated immunity here utilized.

Relationship between some obstetric landmarks and the concentration of alpha-fetoprotein in maternal blood.

Alpha-fetoprotein (AFP) quantitation in maternal blood has been used for prenatal diagnosis of anencephaly, spina bifida and some other congenital abnormalities. The levels of AFP in pregnancy serum are greatly dispersed within each gestational period, what makes the test of difficult interpretation mainly in border line cases. The factors which contribute to this variability are still poorly understood. They must act either on the synthesis or catabolism of the protein, or on the permeability of the fetal-maternal barrier. In an attempt to elucidate some of these factors, the levels of AFP in serum of 89 women at 32 to 34 weeks gestation and of 115 women at term were measured by radioimmunoassay and related to several obstetric variables such as parity, pregnancy number, 1 - minute Apgar score, smoking habit and sex of newborn. It was seen that parity and pregnancy number do not correlate with the levels of AFP in pregnancy serum. Smokers, particularly those who smoke more than a pack per day, however, had higher levels of the protein in their blood. The interpretation of these data should take into consideration the fact that smoking causes vasoconstriction and important vascular alterations similar to the ones encountered in diabetic angiopathy. It is possible that an increased microvascular permeability of placenta and/or membranes to proteins of the size of AFP from the fetus to maternal circulation may explain the greater levels of the protein in serum of smokers.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of human peripheral blood lymphocytes in the presence of cord sera: relationship of lymphocyte transformation with number of pregnancies and levels of alpha-fetoprotein.

Peripheral blood lymphocytes were stimulated with various mitogens (PHA, Con A and PWM) and allogenic cells in the presence of cord serum. The cord sera suppressed more effectively certain T cell populations. This immunoregulatory response of cord serum was compared with nonpregnant and pregnant sera from different gestations. Although the cord sera showed significantly higher inhibition compared to normal adult serum but the serum from gravidae in late gestation proved more inhibitory compared to cord serum. No correlation was found between the levels of alpha-fetoprotein (AFP) in the cord sera and the degree of inhibition observed in the cultures. As previously described for pregnant sera the cord serum obtained from women with different numbers of pregnancies did not correlate with the inhibition of cellular proliferation. Our results suggest a possible different suppressor factor in pregnant and cord sera and also excludes the possibility of AFP in cord sera as a suppressor agent of cell-mediated immunity.

Inhibition of lymphocyte transformation by serum from pregnant women: lack of correlation with levels of alpha-fetoprotein.

Lymphocytes from pregnant and non-pregnant women were stimulated with optimal doses of phytohaemagglutinin (PHA) in order to detect any possible suppression of the maternal cellular immune capabilities. No major differences were observed. Similar cultures using lymphocytes from normal healthy individuals were exposed to sera from pregnant and non-pregnant women. A consistent inhibitory influence, more pronounced at the end of gestation, was identified in the sera from pregnant women. No correlation was found between the levels of alpha-fetoprotein in the pregnant sera and the degree of inhibition observed in the cultures.

Cord serum AFP and the immunological status of the mother: a lack of correlation.

Cord serum from 139 newborns was analysed for alpha-fetoprotein and immunoglobulin G and the results correlated with the obstetric records of the mothers. No significant correlation was found in comparing either alpha-fetoprotein or immunoglobulin G levels with the previous obstetric experiences of the mothers. A previously reported sex difference of alpha-fetoprotein levels at birth was not found in this study. These results are discussed in the light of the possible immunosuppressive effects of alpha-fetoprotein.