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Biomedical subjects

A P Adams

Publications and source records attributed to A P Adams.

At least 19 recordsLinked to original sources
PubMed2001

Ectopic transplantation of equine invasive trophoblast.

A system for transplanting invasive equine trophoblast (i.e., chorionic girdle) to ectopic sites has been developed as a means to study the differentiation of this tissue and to assess maternal immune responses to the conceptus tissue in a site outside the uterus. Chorionic girdle was isolated from Day 33 to 34 conceptuses and surgically placed into the vulvar mucosa or subdermal skin of recipient mares. Biopsy specimens of the graft sites for immunohistochemical staining were taken at weekly or biweekly intervals after grafting. Serum samples were collected from each recipient and tested for antibody to donor major histocompatibility complex (MHC) class I antigens using the lymphocyte microcytotoxicity assay. Transplanted trophoblast cells expressed differentiation markers associated with invading chorionic girdle and endometrial cup cells. The transplanted trophoblast cells were also labeled by an antibody to eCG. Strong cellular and humoral immune responses to the transplanted tissue were mounted by the recipients, similar to those occurring during normal equine pregnancy. Despite these responses, the invasive trophoblast transplants survived for at least 28 days after grafting and downregulated MHC class I antigens, as do the mature endometrial cup cells in equine pregnancy. These findings suggest that invasive equine trophoblast has the capacity to differentiate fully in equine nonuterine tissues, and that it can evade maternal immune responses independent of the physiological state of pregnancy and in sites other than the uterus.

Animals↗
PubMed1996

A new tracheal tube for difficult intubation.

We have compared a new Portex tracheal tube with the Oxford tube in performing simulated grade 3 difficult intubations. The Portex tube was modified so that the bevel faced backwards, as in the Oxford tube. A gum elastic introducer was used with both tubes. The time taken and number of attempts needed were recorded, with changes in arterial pressure, heart rate and incidence of sore throat. Both tubes were successful in avoiding the problem of obstruction at the cords, which occurs when a standard Magill tube is used with an introducer. Thus the new tube has the merits of the Oxford tube without the disadvantages of rubber. It is suitable for both easy and difficult intubations with advantages in safety, cost and convenience. An unexpected but important finding was a clear learning effect, despite both investigators being familiar with the technique at the outset. Over the course of the study, intubation time decreased progressively (P < 0.001). This provides new evidence of the need for trainees to practise the art of intubation when the cords are not visible. Our estimate of the learning "half-life" was 15 intubations; we conclude that 30 simulated grade 3 intubations would be a reasonable objective for trainees before handling high-risk cases.

Adult↗
PubMed1993

Tracheal intubation in a mannikin: comparison of the Belscope with the Macintosh laryngoscope.

Tracheal intubation carries a risk of accidental oesophageal intubation; this is increased with inexperienced trainees, and in patients with a difficult airway. The recent introduction of an angulated laryngoscope, the Belscope, may permit a better view of the vocal cords and increase the accuracy of orotracheal intubation. To determine how easy it is to learn to use the Belscope compared with the traditional Macintosh laryngoscope, a group of medical students attempted to intubate a mannikin which had been modified to simulate a difficult intubation. Time to intubation was fast with both laryngoscopes, although faster with the Macintosh, but the Belscope produced an unexpected greater incidence of failed intubation.

Anesthesiology↗
PubMed1993

Inadvertent suppression of a fixed rate ventricular pacemaker using a peripheral nerve stimulator.

Electromagnetic interference usually produces only minor effects in patients with pacemakers. Nevertheless, the possibilities of serious and even fatal consequences of this complication must be recognised. This case reports an unusual anaesthetic source of interference, caused by activation of a popular nerve stimulator, resulting in cardiac arrest in a patient with a fixed-rate ventricular pacemaker.

Aged↗
PubMed1993

Pre-oxygenation: an easy method for all elective patients.

The transparent plastic facemask has been investigated as a pleasant method of pre-oxygenation for elective non-high risk cases in 60 healthy ASA I or II patients randomly allocated to two groups. The patients in the pre-oxgenated group (n = 30) received 8 litre min-1 oxygen through a plastic facemask for 3 min whereas those in a control group (n = 30) were not pre-oxygenated. In all patients anaesthesia was induced with propofol 2.5 mg kg-1, fentanyl 1 ug kg-1 and atracurium 0.6 mg kg-1. Manual ventilation of the lungs using a Mapleson A breathing system was performed for 2 min with 50% oxygen in nitrous oxide prior to oral intubation. Arterial saturation in the pre-oxygenated group rose significantly from a mean baseline value of 96.4 (+/- 0.9)% to 99 (+/- 0.8)% (P < 0.01) and then remained stable both after induction and intubation: 99.1 (+/- 0.8)% and 98.9 (+/- 1.1)% respectively. In the control group arterial saturation dropped sharply within 20 s following induction to a mean of 89.8 (+/- 3.1)%, and it was 30 s before arterial saturation reached the equivalent value in the pre-oxygenated group as a result of manual inflation of the lungs. An 8 litre min-1 oxygen flow via a standard transparent plastic facemask is a simple, feasible and acceptable method for routine pre-oxygenation for all elective cases.

Adult↗
PubMed1992

Endotracheal intubation skills of medical students.

The ability and confidence of clinical medical students to insert endotracheal tubes correctly and quickly and to recognize oesophageal misplacement was evaluated. Ten (33%) of the medical students intubated the trachea correctly at their first attempt but 14 (47%) incorrectly identified the position of the endotracheal tube. However, recognition improved by their second and third attempts (70% and 80% respectively). Ninety-three percent of students intubated correctly on their third attempt. Although medical students can obtain better results at correct tube placement with repeated attempts under optimum conditions--a practice effect--and do better at recognizing correct tube placement there is still a persistent failure to recognize endotracheal tube misplacement, ie oesophageal intubation. It is the ability to recognize oesophageal intubation promptly that is a life-saving skill. This essential skill should be taught during the introductory anaesthesia programme through the use of clinical patients.

Adolescent↗
PubMed1991

Oxygen delivery systems--a comparison of two devices.

Two low-volume, variable performance oxygen delivery systems were compared in conscious spontaneously breathing volunteers. Oropharyngeal oxygen concentrations were measured during periods of nose and mouth breathing. The systems were studied at oxygen flow rates of 2 or 4 litres/minute. The performance of both systems was similar under the test conditions but the nasal catheter is preferable in terms of cost.

Anesthesia Recovery Period↗
PubMed1991

Hysteria. A cause of failure to recover after anaesthesia.

Hysteria as a cause of failure to recover consciousness following general anaesthesia is a rare event. This case report describes such an instance in a young, healthy 22-year-old female suffering severe dental phobia who was undergoing dental conservation. The literature is reviewed and a summary of the possible physiological mechanisms involved is given.

Adult↗