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Biomedical subjects

P A Lindsay

Publications and source records attributed to P A Lindsay.

9 recordsLinked to original sources
PubMed1995

Intraoperative semiquantitative keratometry using the keratoscopic astigmatic ruler.

Intraoperative keratometry enables the surgeon to set an appropriate amount of corneal astigmatism with the suture tension. Errors in estimating or measuring the astigmatism can occur with hand-held keratometers because the distance an object is held from an astigmatic cornea influences the shape of the elliptical image. Thus hand-held instruments should be held at a calibrated distance. We have designed a new hand-held keratometer, the keratoscopic astigmatic ruler, to assess the magnitude of corneal astigmatism. It consists of a rack of elliptical keratoscopic lenses corresponding to increasing magnitudes of astigmatism and is made from inexpensive autoclavable injection-molded plastic. The ruler's keratoscopic lenses refract light, creating a real aerial image above the cornea that produces a bright and easily determined corneal reflection. The ruler incorporates a sight to allow the user to hold the ruler at the correct distance.

Astigmatism↗
PubMed1994

Bain circuit occluded by foreign body.

The purpose of this report is to describe a potentially hypoxic event which occurred during mask induction with the Bain circuit in a healthy. ASA I boy. Failure of induction occurred because a pop-off weight from a bubble bottle was lodged in the elbow connecting the Bain circuit to the mask and prevented gas flow. Pethick and Foëx-Crampton Smith tests of the Bain circuit could also have missed this condition. Such an anaesthetic mishap could occur with any breathing circuit which is re-used. Although there was no serious misadventure, the potential for an hypoxic complication with either intra-venous induction of anaesthesia, or dislodging of the weight into the airway was significant. We conclude that the standard tests of system patency do not ensure safety.

Anesthesia, Closed-Circuit↗
PubMed1992

A quantitative scale for the Barrett keratoscope.

By allowing the surgeon to measure and modify corneal curvature during wound closure, intraoperative keratometry can reduce postoperative astigmatic errors. A number of keratometric devices have been developed over the last 10 years, each offering a compromise between cost, accuracy and ease of use. The Barrett keratoscope is a simple, inexpensive hand-held device which gives a qualitative indication of the degree of astigmatism. Addition of a transparent overlay, as described in this paper, sets the distance at which the keratoscope is held and allows the magnitude of the astigmatism to be determined, thereby enabling refined adjustment of the suture tension during wound closure. We describe the error in estimation of astigmatism due to the effect of the distance at which the keratoscope is held from the cornea.

Anthropometry↗
PubMed1979

The big and/or soft spleen: a survey of necropsy specimens.

A statistical survey of the necropsy population, for the year 1973, at the Veterans Administration Hospital, Long Beach, Calif, was performed to determine changes occurring in the spleen. When cirrhosis of the liver was present, spleens were usually enlarged but not substantially firmer. In cases in which there was no cirrhosis, severe systemic infection was not accompanied by splenomegaly, although spleen softening was present. Generally, spleen size did not appear to be related to its own consistency. However, when cirrhosis of the liver was present, severe infection was accompanied by a decrease in the size of the spleen, with no change in consistency; but in these cases, there was less infection at the time of death. Splenomalacia was not shown to be related to postmortem autolysis. The spleen weight decreased only slightly with aging.

Adult↗
PubMedDate not supplied

Suxamethonium apnoea masked by tetrahydroaminacrine.

A case is reported of a patient who was given THA with suxamethonium and who demonstrated a prolonged apnoea. This patient was later shown to have a variant cholinesterase enzyme. The different techniques of THA and suxamethonium administration are discussed and it is suggested that an initial dose of suxamethonium should precede a THA-suxamethonium combination in order to try and avoid a prolonged apnoea.

Acridines↗