Airway hypocapnia increases microvascular leakage in the guinea pig trachea.

We have previously shown that airway hypocapnia induced bronchoconstriction in the guinea pig lung by releasing tachykinins. To examine whether airway hypocapnia could also cause an increase in airway microvascular leakage, a tracheal segment was isolated in vivo in anesthetized guinea pigs and unidirectionally ventilated (200 ml/min) for 1 h with fully conditioned air (0% CO2) or isocapnic gas (5% CO2). The lungs were ventilated through a distally placed tracheal cannula. Microvascular leakage was quantitated by the injection of Evans blue (EB) and its extraction from the tracheal segment. EB extravasation was increased in tracheae exposed to 0% CO2 (52.3 +/- 2.0 micrograms/g wet tissue) compared with tracheae exposed to 5% CO2 (26.4 +/- 2.9 micrograms/g; p less than 0.05) and to tracheae from spontaneously breathing guinea pigs (25.2 +/- 2.3 micrograms/g; p less than 0.05). Groups of animals in which trachea were unidirectionally ventilated with 0% CO2 were then pretreated with a range of drugs in an attempt to determine the mediators responsible for the microvascular leakage with 0% CO2. Capsaicin and morphine pretreatment did not significantly alter 0% CO2-induced EB extravasation, and phosphoramidon prevented rather than increased extravasation, suggesting that tachykinins did not play a role. The hypocapnia-induced increase in microvascular leakage was, however, prevented by indomethacin pretreatment and significantly attenuated by dazmegrel, a thromboxane synthetase inhibitor. We conclude that airway hypocapnia causes microvascular leakage in the guinea pig trachea and that this effect is mediated by prostaglandins and/or thromboxane.     

Effect of timolol versus pilocarpine on visual field progression in patients with primary open-angle glaucoma.

BACKGROUND: Relatively few studies have been conducted linking decreasing intraocular pressure (IOP) to preservation of visual field. This investigation was conducted to determine if this link could be made and to compare the long-term effect of two ocular hypotensive agents on preservation of visual field. METHODS: In an observer-masked study, 189 patients with primary open-angle glaucoma received either timolol or pilocarpine by random allocation. The dose of antiglaucoma agent was increased from 0.25% to 0.5% twice daily for timolol or from 2% to 4% four times daily for pilocarpine if the initial IOP response was inadequate. After an on-treatment baseline, visual fields were followed every 4 months for 2 years using the Octopus program 32. RESULTS: Compared with timolol, significantly more patients receiving pilocarpine discontinued use because of inadequate IOP control (P < or = 0.01). By comparing the mean visual field scores, it can be seen that the pilocarpine group had a significantly worse score at all timepoints from month 4 to month 24. The pilocarpine group also had a greater mean number of test loci with decreased sensitivity of 5 or more decibels (dB) at all timepoints. The mean within-patient regression slope for timolol was 0.01 dB/month and for pilocarpine was -0.06 dB/month (P < 0.01). The study has shown that over a 2-year period, patients treated with pilocarpine 2% or 4% four times daily experienced a significantly greater visual field deterioration than that seen in patients receiving either 0.25% or 0.5% timolol twice daily. CONCLUSION: Although these data do not support a link between lowering of IOP and visual field preservation, treatment with timolol was associated with significantly less visual field loss than treatment with pilocarpine.     

Criteria for evaluating the clinical and practical utility of models used by nurses

Arguably, nursing, like all health care disciplines, is an applied science. Essentially, this refers to the application of theory in order to understand and respond to the health problems of clients. These theories may be drawn (borrowed) from any applied science, or generated inductively from clinical nursing practice. Alternatively, nurses may attempt to apply deductive theory (global theoretical frameworks) known as nursing models. In this paper, all theoretical approaches, irrespective of origin, are referred to as models used by nurses. Thirteen criteria by which clinicians, and others, can evaluate the clinical and practical utility of models used by nurses which are expressed in the form of questions are identified and discussed. The criteria are an extension, both in detail and in number, of those developed by Reynolds and Cormack and subsequently applied by those writers to the Johnson Behavioural System Model of Nursing. The value, or otherwise, of individual models, or of models in general, will not be discussed in this paper. However, the authors propose that if the evaluation criteria described here are applied to existing models, serious deficits will be identified in relation to their clinical and practical utility.     

Normative data of hemoglobin concentration and free erythrocyte protoporphyrin in a private pediatric practice: a 1990 update

Free erythrocyte protoporphyrin (FEP) and hemoglobin (Hgb) concentrations were tested in 790 children in a private pediatric office; results were compared to those obtained in 1984. Only 16 children (2%) had abnormal FEPs in 1990 compared to 76 children (9.6%) in the earlier study. The mean FEP in the normal group also decreased significantly in each age group studied. The hemoglobin concentrations were not significantly different in most of the age groups studied. Screening for iron deficiency in our pediatric practice by determining hemoglobin and FEP concentrations had a much lower yield in 1990 than in 1984.     

Diagnostic performance of nocturnal penile tumescence studies in healthy, dysfunctional (impotent), and depressed men

Nocturnal penile tumescence (NPT) studies were evaluated in 17 men with a clinical diagnosis of organic erectile dysfunction in comparison to age-matched healthy controls (n = 17) and depressed men (n = 17). The dysfunctional group had significantly fewer NPT episodes and reduced maximal penile tip changes when compared to healthy controls and depressed patients. Further, the dysfunctional group had significantly diminished erectile fullness and reduced penile rigidity. Diagnostic performance of polygraphic (night 1) and visual inspection (nights 2 or 3) components of the NPT protocol were examined in these criterion groups. A diagnostic classification based on polygraphic measures successfully discriminated 73.5% of dysfunctional and healthy control subjects, but classified 47% of depressives in the dysfunctional range. Use of visual inspection indices correctly identified 88% of the dysfunctional sample and 94% of normal controls, and reduced the "false-positive" rate in depression to only 18%. Results support the diagnostic utility of NPT studies, particularly when enhanced by visual inspection procedures. Nevertheless, the presence of major depression may confound interpretation of such studies.