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Biomedical subjects

N Johnson

Publications and source records attributed to N Johnson.

At least 19 recordsLinked to original sources
PubMed1992

Should we use prostaglandins, tents or progesterone antagonists for cervical ripening before first trimester abortion?

Sixty-four women requesting first trimester termination of pregnancy were recruited into a comparative cohort study comparing the cervical ripening properties of a mechanical dilator (Lamicel; n = 17), prostaglandin, antiprogesterone and placebo control (n = 15), gemeprost; n = 17) and mifepristone; n = 15). Compared to the placebo group, all 3 active agents dilated the cervix (p < 0.02) and they significantly reduced the force required to dilate it to 8 mm Hegar (p < 0.001). Although Lamicel insertion resulted in the largest pre-operative cervical dilatation all agents are effective. Therefore the cervical priming agent of choice should be the most convenient to use and the one with least side-effects. The oral antiprogesterone, Mifepristone, is the easiest to administer and has less side effects.

Abortion, Induced↗
PubMed1992

Human immunodeficiency virus infection among inner-city adolescent parturients undergoing routine voluntary screening, July 1987 to March 1991.

OBJECTIVE: The objective of our study was to describe the human immunodeficiency virus epidemic among pregnant adolescents undergoing follow-up in a large inner-city hospital. STUDY DESIGN: We conducted a case-control study comparing demographic and risk behaviors of seropositive and seronegative adolescents (aged 13 to 20) identified from a population undergoing routine voluntary antibody screening at Grady Memorial Hospital in Atlanta, Georgia, between July 1987 and March 1991. RESULTS: Of 10,794 pregnant adolescents screened, 51 (4.7/1000) were infected with human immunodeficiency virus. More than one fourth of case patients were < or = 17 years old. Significantly more case patients than controls reported a history of crack cocaine use (10 [19.6%] vs 23 [8.2%] p < 0.05). A majority (58.8%) of case patients reported no risk factors for infection, and the remainder (41.2%) were presumably infected by heterosexual contact. Thirty-nine controls (13.8%) had self-identified risk factors for infection. CONCLUSIONS: Pregnant adolescents in our center are at risk for human immunodeficiency virus infection and should be targeted for human immunodeficiency virus education and risk reduction counseling.

Adolescent↗
PubMed1992

Using decision analysis to calculate the optimum treatment for microinvasive cervical cancer.

Decision theory was used to calculate the optimum treatment of microscopic squamous cervical cancer using probabilities obtained from an exhaustive literature review and a range of plausible value estimates. This showed that if there is no vascular involvement, survival is maximised by conservative treatment if tumour invasion is less than 3 mm while treatment by radical surgery results in maximal survival rates if the tumour invasion is over 3 mm. Radical surgery also maximises survival for smaller lesions where lymph channel involvement is present, especially if a surgical mortality at the lower end of the reported range is assumed. Refinement of our analysis to include an assessment of patient values showed that these conclusions are still valid regardless of the patient's relative preference for death from surgery or death from cancer. However, the wish to preserve fertility sharply reduces the overall net benefit of surgery. Conservative treatment becomes the preferred option for all microinvasive lesions even for patients who are prepared to trade-off a small (e.g. 2%) risk of death in order to retain their fertility.

Adult↗
PubMed1992

Is transcutaneous electrical nerve stimulation of any value during cervical laser treatment?

OBJECTIVE: To assess the value of transcutaneous electrical nerve stimulation (TENS) during cervical laser therapy. DESIGN: Randomized three arm controlled clinical trial comparing (i) TENS, (ii) local anaesthetic and (iii) TENS plus local anaesthetic (direct infiltration of 2% lignocaine and 0.03 iu/ml octopressin). SETTING: Colposcopy Unit adapted to run randomized trials. SUBJECTS: 100 women with CIN and no previous experience of cervical surgery. MAIN OUTCOME MEASURE: Visual linear analogue pain scores. RESULTS: The median pain score associated with TENS was greater than the score associated with local anaesthesia (23% compared with 17%; P = 0.1). Combining TENS with local anaesthesia did not further reduce pain scores. CONCLUSION: Although there was considerable consumer satisfaction with TENS it provided no additional pain relieving effect in addition to direct infiltration of lignocaine and it is inferior to lignocaine alone. We are unable to advocate the use of TENS for laser treatment of the cervix.

Adult↗
PubMed1992

Do fetal pulse oximetry readings at delivery correlate with cord blood oxygenation and acidaemia?

OBJECTIVE: To assess the accuracy of a pulse oximeter in the fetus. DESIGN: A prospective descriptive study, comparing oxygenation and acidaemia of cord blood with oxygen saturation in the arteries of the fetal scalp measured by a pulse oximeter just before delivery. The data were collected using an experimental pulse oximeter and a sensor specifically adapted to cope with the problems of fetal pulse oximetry. SETTING: The labour ward in a teaching hospital. SUBJECTS: Thirty seven Caucasian fetuses presenting by the vertex in normal uncomplicated labour. MAIN OUTCOME MEASURE: Fetal pulse oximetry reading shortly before birth, umbilical cord oxygenation and pH, and Apgar scores. RESULTS: Data of sufficient quality were obtained from 28 fetuses. There was a highly significant correlation between pulse oximetry reading and umbilical vein oxygen saturation r = 0.59, P = < 0.001). There was also a significant correlation between the pulse oximeter reading and cord blood pH (vein: r = 0.57, P = 0.002, artery: r = 0.63, P = 0.001). Apgar scores were not related to the oximetry results. CONCLUSION: Pulse oximetry readings reflect fetal oxygenation at birth.

Apgar Score↗
PubMed1991

The effect of squatting on pelvic dimensions.

Lateral X-ray pelvimetry was performed on 63 women in the sitting and squatting positions on the 5th or 6th post-natal day to assess whether squatting has any effect on pelvic dimensions. Four assessors measured the inlet and outlet pelvic dimensions from 25 cases with good radiographic views in order to minimise observer bias. There was no statistically significant change in pelvic dimensions with squatting. Some possible explanations are discussed.

Female↗
PubMed1991

Use of computerised general practice data for population surveillance: comparative study of influenza data.

OBJECTIVE: To assess the potential for using routine computerised general practice data for surveillance of illness. DESIGN: Comparison of the incidence of influenza during the 1989 epidemic derived from a computerised database with that derived from the Royal College of General Practitioners's weekly returns service--a well established predominantly manual surveillance system. SETTING: 433 general practices throughout the United Kingdom that used a commercial computer system linked to a central databank. MAIN OUTCOME MEASURE: Incidence of influenza. RESULTS: The slope of the influenza epidemic curve was essentially the same whether derived from the routine computerised data or royal college's weekly returns service data, and the computerised data were geographically consistent. Throughout the study period, however, the computer derived incidence was between one third and one quarter of that derived from the royal college's system (which is served by practitioners trained in surveillance methods). The peak weekly rates were 164 cases per 100,000 for the computerised system and 583 cases per 100,000 for the royal college's surveillance system. CONCLUSIONS: The apparent underreporting in the routine computerised data probably reflects lack of motivation and experience in disease surveillance and haphazard computer entry (particularly of consultations that took place outside of the surgery and consultations that did not result in a prescription), along with overestimation of the population under surveillance. Nevertheless, routine computerised surveillance allows rapid data collection from a large number of practices over a wide geographical area and would greatly augment existing methods.

Computer Systems↗
PubMed1991

Excretion of mutagens following chemotherapy.

The mutagenic activity of urine was evaluated in children receiving single and multiple agent chemotherapy to determine the duration of carcinogenic risk to health care personnel and family contacts. Urine samples from 21 children were evaluated before and daily for 5 days after chemotherapy administration. Mutagenic activity, a sensitive though not specific indicator of carcinogenic risk, was assayed using mutant strains of Salmonella typhimurium (the "Ames test"). Validity of the assay was confirmed by demonstrating mutagenic activity in urine samples from 17 adult cigarette smokers but not from 21 adult nonsmokers (24/24 versus 0/37, p less than 0.001). None of the 21 children tested demonstrated mutagenic activity before chemotherapy administration. Following single agent dactinomycin, cyclophosphamide, daunorubicin, doxorubicin, methotrexate, or vincristine, mutagenic activity was demonstrated for 2 days (5/5 at 1 and 2 days and 0/5 at 3 days). Following multiple agent chemotherapy using two or three of the latter drugs on a single day, mutagenic activity was demonstrated for 4 or 5 days (16/16 at 1, 2, 3, and 4 days, and 4/16 at 5 days). Based on these observations with urine, and presumably other body fluids, precautions are recommended for 2 days following single agent and at least 5 days following multiple agent chemotherapy.

Adult↗
PubMed1991

Fetal monitoring with pulse oximetry.

Continuous fetal monitoring was achieved with a fetal scalp pulse oximetry sensor in 86 labours. The average recorded fetal oxygen saturation in early labour (cervical dilatation less than 5 cm) was 68% (SD 13%). At the end of labour (cervical dilatation greater than or equal to 9 cm) the recorded mean oxygen saturation was 58% (SD 17%). The largest range of readings during a single labour was 81%-11% but this drop was associated with cord compression. The average SD during 1 h of normal labour was 10%. A second group of 40 fetuses was monitored during induction of labour before and after elective amniotomy. Oxygen saturation did not appear to change after amniotomy (mean change -0.4%, SD 1.2%) and there was no difference between mean antenatal or early intrapartum readings. We excluded the amniochorionic membranes as a possible source of data corruption by measuring their in vitro absorption spectra and confirming that they do not preferentially absorb light of either 660 or 940 nm wavelength. Non-invasive pulse oximetry can be used to monitor the fetus before and during labour.

Amnion↗
PubMed1991

Experience with tissue expansion vaginoplasty.

In vaginal agenesis, a vagina can be treated by tissue expansion vaginoplasty. We have performed 17 such procedures. One procedure was abandoned because of infection of the temporary implant. In four women the first stage had to be repeated: in one the implant was placed too superficially, in another it did not provide adequate expansion, in a further instance the implant became infected and the fourth woman received a surgical wound to her labia. The second stage was successful in all 16 women who now have a vagina lined with viable epithelium. The vaginal length was satisfactory in all but one. Two women complained of a vaginal discharge due to hair at the vaginal vault, two women developed postoperative haematomas and one experienced introital stenosis. The disadvantage of the procedure is that it requires two operative stages and involves a prolonged hospital stay but it is not technically complex and results in a full length vagina that does not require dilatation.

Adolescent↗
PubMed1991

The free-flap vaginoplasty; a new surgical procedure for the treatment of vaginal agenesis.

The ideal operation for a young woman born without a vagina would be a one stage procedure, creating a functionally normal vagina without cosmetically unattractive scars, without the need for subsequent dilatation, stents or obturators. This goal was achieved with a free flap vaginoplasty using a full thickness skin graft taken from the scapula region. The blood supply of the graft was maintained by microvascular anastomosis of the graft pedicles to vessels in the groin. The operation has been performed in three young women who were born with uterine hypoplasia and vaginal agenesis. We experienced no unexpected complications, the procedure was well tolerated and left our patients with a good length, fully functional vagina. However, the operation is a major undertaking and needs to be performed by those with expertise in plastic surgery as well as in gynaecology.

Adolescent↗
PubMed1991

Effect of cervical traction with a tenaculum on the uterocervical angle.

The effect of cervical traction on the uterocervical angle was measured radiographically in 24 women undergoing diagnostic curettage. A radio-opaque guidewire was inserted through the cervical canal into the uterine cavity and a lateral pelvic X-ray taken before and after traction. The traction force was measured with a spring-balance attached to the tenaculum. Cervical traction in a caudal direction (force 2 N) reduced the median uterocervical angle, from 75 degrees to 10 degrees (P = 0.001). Moderate cervical traction straightens the uterus and the routine use of a tenaculum theoretically makes insertion of an intrauterine device safer and the passage of an embryo transfer catheter less traumatic.

Cervix Uteri↗
PubMed1991

At what level of collective equipoise does a clinical trial become ethical?

It has often been argued that if a clinician cannot decide which of two treatments to offer, a trial may be ethical, but it is unethical if she/he has a preference. Since individual clinicians usually have a preference, most trials could be judged unethical according to this line of argument. A recent important article in the New England Journal of Medicine argued that individual preferences are not as important as the collective uncertainty of informed clinicians. If clinicians are equally divided, there is a state of collective equipoise and a trial is ethical. However, clinicians will seldom be exactly equally divided. We conducted an ethometric study to find out how much collective equipoise can be disturbed before the potential subjects in a trial think that it is unethical. Half of our subjects perceived a trial as unethical when equipoise was disturbed beyond 70:30. In other words, when 70 per cent of experts favour one treatment, 50 per cent of subjects would prefer that treatment to be administered rather than subjected to critical assessment. When equipoise is disturbed beyond 80:20, less than 3 per cent of subjects would consider human trials morally justifiable.

Aged↗
PubMed1991

Brainstem vascular accidents and cranial arteritis.

Cranial Arteritis (Giant Cell Arteritis) is a clinical diagnosis supported by a raised erythrocyte sedimentation rate (ESR) and if required confirmed by a temporal artery biopsy. This case reports on an unusual presentation where a delay in the diagnosis resulted in visual impairment, illustrating the need for awareness of diagnosis in acute strokes in the elderly.

Aged↗