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Biomedical subjects

G McLaughlin

Publications and source records attributed to G McLaughlin.

15 recordsLinked to original sources
PubMed1992

The reality of dental CAD-CAM: hype or hope?

Dental CAD-CAM has become a clinical reality. It holds great promise to help provide a higher level of service to the patient, while allowing the dentist to spend more time on patient needs than on the mechanics of restoration production. Still, this technology is not suited for every dental office. This paper discusses the technique of CAD-CAM, its potential and its limitations so the dentist can better evaluate the appropriateness of this new modality for his or her own office.

Computer-Aided Design↗
PubMed1988

Comparative potency of atropine sulphate and glycopyrrolate on heart rate in man.

Disagreement as to the effect of glycopyrrolate and atropine sulphate at various dosages on heart rate has been reported in the literature. Of particular interest is the question of whether small doses of glycopyrrolate cause bradycardia. Three groups of subjects were studied. The QRS complexes of the electrocardiogram were continuously recorded on a microcomputer. Group 1 consisted of 10 healthy volunteers who were given two doses of atropine sulphate 1.25 micrograms kg-1 and glycopyrrolate 0.75 micrograms kg-1, in random order at two different times, i.v. Monitoring continued until heart rate returned to baseline. Group 2 consisted of 24 women, ASA class I or II, scheduled for gynaecological operations. Each patient received fractionated i.v. doses of either atropine sulphate 2.5, 2.5 and 5 micrograms kg-1 or glycopyrrolate 1.5, 1.5 and 3.0 micrograms kg-1 at 3-min intervals. Heart rate was measured continuously for 1 h before drug injection and for 10 min after the last dose. Group 3 consisted of six volunteers given both drugs in the same dose and time schedule as Group 2, but heart rate was monitored for 180 min after the last dose. In Group 1, the incidence of bradycardia and increases in heart rate after the first dose were statistically significant for both atropine sulphate and glycopyrrolate when compared with baseline values. In Group 2, both drugs significantly increased the heart rate and had similar times to peak effect. In Group 3, bradycardia occurred only with atropine sulphate. Increases in heart rate, peak heart rate and duration of action were similar with both drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Tidal volume changes due to the interaction of anesthesia machine and anesthesia ventilator.

Tidal volume (VT) delivered by mechanical ventilation during anesthesia may be influenced by factors related not only to the patient and the breathing circuit, but also to the interaction between the anesthesia machine and the anesthesia ventilator. To characterize this interaction, we studied in a test lung the effect of fresh-gas-flow (FGF) (0.25, 2.5, 5, and 10 L/min), inspiratory-to-expiratory time ratio (I:E) (1:1, 1:2, and 1:3), and ventilatory frequency (8, 12, and 16 breaths/min) at fixed ventilator bellows excursions of 300, 600, and 900 ml. The influence of these variables was also estimated mathematically for a pediatric situation: a bellows excursion of 50 ml at 20 and 30 breaths/min. Each variable studied was associated with an increase, sometimes dramatic, in the delivered VT compared with that which was set. The VT augmentation was greatest at the highest FGF rate, largest I:E ratio, and slowest respiratory rate. Because the magnitude of the augmentation is independent of the VT setting, the percent increase is much larger for pediatric settings. For example, with VT set at 50 ml, delivered VT ranged from 71 ml (FGF 2.5 L/min, I:E 1:3, and 30 breaths/min) to 300 ml (FGF 10 L/min, I:E 1:1, and 20 breaths/min). Thus it is possible in the pediatric situation to increase the delivered VT by sixfold without changing the ventilator bellows excursion. The magnitude of the changes was slightly larger for the VT settings for adult patients because of the slower respiratory rate. This VT augmentation can be predicted by the product of FGF (ml/s) and inspiratory time (seconds).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1987

The electronic clipboard: a semiautomatic anesthesia record.

An electronic clipboard has been designed, built, and tested, which produces an anesthesia record semiautomatically. Physiologic data are recorded up to once a minute automatically. Two keys number and time 'drug' and 'event' entries. The accurate monitoring of heart rate and blood pressure and the timing of event data are much improved over hand-written entries.

Anesthesiology↗
PubMed1986

Entry of Bartonella bacilliformis into erythrocytes.

Bartonella bacilliformis, which causes the human diseases Oroya fever and verruga peruana, binds to human erythrocytes in vitro and produces substantial and long-lasting deformations in erythrocyte membranes, including cone-shaped depressions, trenches, and deep invaginations. The deforming force is probably provided by the polar flagella of these highly motile bacteria. Deep invaginations containing bacteria are commonly seen, and membrane fusion at the necks of the invaginations leads to the formation of intracellular vacuoles containing bacteria. Fluorescent compounds present externally render the vacuoles fluorescent and, occasionally, lightly fluorescent cells are seen, suggesting that the vacuoles sometimes rupture to admit the bacteria to the cytoplasm. Vacuoles present in fluorescent erythrocytes prepared by preloading the erythrocytes with fluorescent compounds are seen as dark areas from which the fluorescent marker is excluded. Entry of the bacteria appears to be the result of a process of forced endocytosis.

Bacterial Adhesion↗
PubMed1985

Tissue hypoxia distal to a Peñaz finger blood pressure cuff.

The Peñaz finger method to measure blood pressure uses a finger cuff in which the pressure level fluctuates in the vicinity of the mean arterial pressure level and thereby interferes with the circulation of blood to and from the fingertip. We measured capillary blood gases and saturation of hemoglobin in the finger during Peñaz finger blood pressure (PFBP) monitoring to assess the degree to which it impairs circulation in the fingertip. Within 2.5 minutes after initiating PFBP monitoring, capillary oxygen tension (PO2) had decreased significantly, from about 71 mm Hg to between 49 and 58 mm Hg for up to 50 minutes. These changes were quite different from those occurring when an occlusive tourniquet was applied around the finger. Within 10 minutes of tourniquet application, acidosis (pH 7.25), hypercapnia (carbon dioxide tension, 59.0 mm Hg), and hypoxemia (PO2, 29 mm Hg) resulted. Within 30 seconds of releasing the PFBP cuff, capillary blood gas values were back to normal. Interspersing 30-second rest periods every 5 minutes during 35 minutes of PFBP monitoring actually decreased capillary oxygen values compared with monitoring without such rest periods. A finger pulse oximeter distal to the PFBP cuff showed desaturation from an average of 97% to 93.7%, with much variability. However, desaturation was statistically significant within 1 minute of application of the PFBP cuff. Within 1 minute the finger volume increased an average of 0.05 ml. After 1 minute the volumes varied widely and, on the average, returned to normal despite continued PFBP monitoring.

Acidosis↗
PubMedDate not supplied

Future dentistry.

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Aminobutyrates↗