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Biomedical subjects

R A Saunders

Publications and source records attributed to R A Saunders.

At least 73 records · Page 4Linked to original sources
PubMed1979

Coated Vicryl (polyglactin 910) suture in extraocular muscle surgery.

A newly available coated Vicryl (Polyglactin 910) suture was evaluated in laboratory and clinical trials for use in extraocular muscle surgery. The suture retains the increased strength and low antigenicity of uncoated Vicryl suture, while providing easier passage through tissue and improved tying characteristics. The improved handling properties result from the coating which produces a smoother suture surface.

Adolescent↗
PubMed1978

Is air trapping important in the maintenance of the functional residual capacity in the hours after birth?

Serial measurements of thoracic gas volume revealed no evidence of air trapping in maintenance of functional residual capacity (FRC) in healthy term babies in the first days of life. Tidal pressue/volume and flow/volume analysis demonstrated intermittent air trapping in only 2 of 19 such babies. Artificial FRC reduction by continuous positive external pressure of 7 cm H20 induced grunting in 4 babies, but otherwise had no effect on spontaneous breathing pattern or on dynamic compliance. Group mean total pulmonary resistance rose by 52.9% but only one baby demonstrated evidence of air trapping. Our findings suggest that FRC is maintained in the immediate neonatal period by some means other than air trapping.

Age Factors↗
PubMed1978

A study of the role of air trapping in the establishment of the functional residual capacity by analysis of pressure/volume and flow/volume loops.

Pulmonary mechanics were measured in 22 normal, full-term babies as soon as quiet, regular breathing was established. The method included construction of tidal resistance profiles, by which it was demonstrated that 'air trapping' is probably not the major factor in establishing and maintaining the functional residual capacity immediately after birth.

Air↗
PubMed1978

Pulmonary pressure/volume relationships during the last phase of delivery and the first postnatal breaths in human subjects.

Intrathoracic pressure and volume changes during delivery and the first postpartum breaths were measured in 17 term infants. The following findings emerged: (1) Infants were often exposed to high pressures during delivery, when significant volumes of lung fluid were expressed. (2) Despite this, none of the infants' lungs reinflated by passive "elastic recoil." (3) The active inspiratory effort required for reinflation was usually small or moderate, and an "opening pressure" did not appear to be necessary for the initial rise in volume. It is believed that diaphragm and intercostal muscle tone falls or disappears during delivery and returns during the first breath.

Delivery, Obstetric↗
PubMed1978

Tidal pressure/volume and flow/volume respiratory loop patterns in human neonates.

1. Tidal pressure/volume and flow/volume respiratory loops were constructed from records obtained during 98 studies on 48 neonates of various ages and gestations. Records were obtained with a total body plethysmograph and an oesophageal balloon. Total pulmonary resistance was computed at five separate levels in the breathing cycle and results were expressed graphically as tidal resistance profiles by plotting total pulmonary resistance against percentage tidal volume above functional residual capacity. 2. Values obtained for standard pulmonary mechanical measurements and thoracic gas volume were similar to those of other workers. In addition six distinctive resistance profile patterns were found and related to different breathing patterns. 3. The technique appeared to be particularly useful in identifying air trapping and also demonstrated that total pulmonary resistance is open to misinterpretation when measured only at the mid-tidal-volume level, as is the present convention.

Airway Resistance↗
PubMed1978

Effects of delivery by caesarean section on lung mechanics and lung volume in the human neonate.

Lung function tests were carried out in the first 6 hours of life on 26 babies born by vaginal delivery and 10 born by caesarean section. The babies born by caesarean section had a mean thoracic gas volume of only 19.7 ml/kg body weight compared with 32.7 ml/kg for the babies born vaginally. We conclude that this is owing to an excess of lung fluid in the babies born by caesarean section.

Airway Resistance↗
PubMed1978

Longitudinal studies of infants with the Wilson-Mikity syndrome. Clinical, radiological and mechanical correlations.

Simple clinical measurements were performed on a group of 23 very low birth weight babies (less than 1500 g and less than 32 weeks gestation), and combined with pulmonary function studies in 13 cases. The studied included a special single-breath analysis, or Tidal Resistance Profile, which enabled us to detect air trapping. 2 infants developed classical Wilson-Mikity syndrome and 2 further infants exhibited a milder, shorter form of the same disorder. All 4 survived. Results suggest that all infants in this maturity group are at risk of developing Wilson-Mikity syndrome, and that it comprises a wide spectrum of respiratory dysfunction.

Humans↗
PubMed1978

Relationship of intra-oesophageal pressure to mouth pressure during the measurement of thoracic gas volume in the newborn.

During the measurement of thoracic gas volume, mouth pressure changes were compared to oesophageal pressure changes using an oesophageal balloon system. In individual babies the correlation was high, with r values in excess of 0.98. In other babies the correlation was less satisfactory due to cardiac contractions producing artefacts in the oesophageal pressure trace. The overall correlation obtained from analysing 155 respiratory efforts in a group of 21 babies studied on 23 occasions exceeded an r value of 0.90. We conclude that it is valid to use an oesophageal balloon system to measure changes in intrathoracic pressure.

Esophagus↗
PubMed1977

Apnoea induced by airflow obstruction.

Total obstruction of the airways caused all respiratory efforts to stop on 15 occasions in 10 preterm babies. This was not seen in 60 studies on 38 term babies. These findings suggest that failure to achieve an oral airway may not be the only mechanism by which upper airway obstruction might cause the cot death syndrome.

Airway Obstruction↗
PubMed1977

Effects of continuous distending pressure on lung volumes and lung mechanics in the immediate neonatal period.

The effects of CPAP and CNEP on lung mechanics and lung volumes were investigated in a group of 12 healthy newborn infants. Both resulted in a mild suppression of respiration. The fall in TPR50 was far greater during CPAP than during CNEP. Both led to a one third fall in dynamic compliance. Approximately 50% of the distending pressure was transmitted to the mediastinal structures whether applied as CPAP or CNEP.

Airway Resistance↗
PubMed1976

An evaluation of the "CentrifiChem" parallel fast analyser.

The operating principles of the CentrifiChem are briefly described and the results of the evaluation are summarised. The pipettor, the temperature control unit, and the photometer were tested separately, but the remainder of the instrument is interdependent. Up to 10 different tests were used to measure within-batch and between-day precision, and accuracy. Carryover was found to be small, and for the six tests investigated the linearity was good. Estimates are given of the running costs, and also included are sections on the reliability and safety of the instrument. Since it requires only a small volume of serum, it is ideally suited to paediatric requirements. When used as an enzyme analyser it can work at about 200 specimens per hour.

Autoanalysis↗
PubMed1975

The performance of the 'CentrifiChem' parallel fast analyser using packaged reagents.

The CentrifiChem system was used with packaged reagent kits for the following determinations: albumin, alanine and aspartate aminotransferases, creatinine, glucose, and alpha-hydroxybutyrate and lactate dehydrogenases. The linearity obtainable for each assay was investigated, and particular attention was paid to finding the most suitable instrument settings.

Alanine Transaminase↗