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Biomedical subjects

D B Craig

Publications and source records attributed to D B Craig.

At least 73 records · Page 4Linked to original sources
PubMed1975

Post-operative epidural analgesia: effects on lung volumes.

A study was undertaken to assess the role of post-operative pain in reducing Functional Residual Capacity (FRC) and Vital Capacity (VC). The efficacy of post-operative epidural analgesia in reversing these changes was measured in eight subjects after upper abdominal operations. With pain, FRC and VC were 78 per cent and 37 per cent of control respectively. Following epidural analgesia, the values were 84 per cent and 55 per cent. These figures indicate the pain component in the post-operative reduction of these two lung capacities. This partial restoration may be of value in the prevention of post-operative pulmonary complications by avoiding closure of small airways during tidal breathing and by increasing the effectiveness of deep breathing and coughing in the removal of secretions and the reversal of atelectasis.

Adult↗
PubMed1975

Airway closure in pregnancy.

Closing capacity (CC; the lung volume at which dependent lung zones cease to ventilate, presumably as a result of airway closure) and standard lung volumes were measured in twenty-four normal women 21 to 29 years of age in the seated and supine positions. Measurements were made serially during pregnancy and once 6 to 8 weeks post partum (the control period). CC was unchanged during pregnancy, while functional residual capacity (FRC) fell by approximately 15%. The difference between FRC and CC (FRC-CC) was reduced during pregnancy, but in one of the subjects when seated, and in only two supine subjects did CC exceed FRC. FRC-CC was reduced in the supine position as compared to seated. The reduced FRC-CC during pregnancy offers a potential explanation for the observations of abnormally low arterial oxygen tensions (Pao2) during pregnancy in some women, and of reduced Pao2 in pregnant women in the supine as compared to upright position.

Adult↗
PubMed1975

Nitrogen analyzer adaptation for use in the presence of halogenated anesthetics.

Interposition of activated carbon between a nitrogen analyzer needle valve and gas mixtures containing halothane, methoxyflurane, enflurane, or isoflurane eliminated the interfering effects of these agents, but added sampling delays. Placement of a carbon-filled Swinney adaptor in the sampling line between the needle valve and analyzer also eliminated the interference. Linearity of response (range 0 to 80 per cent N2) and sampling delay (40 msec) were unchanged. The 90 per cent fall time (step change 80 to 0 per cent N2) increased from 35 to 100 msec. This adaptation allows rapid analysis of nitrogen concentrations during general anesthesia.

Anesthesia, General↗
PubMed1975

Intraindividual variability in maximal expiratory flow-volume and closing volume in asymptomatic subjects.

The variability of the parameters derived from analysis of the forced vital capacity and the expired nitrogen trace after a vital capacity inhalation of oxygen (closing volume) within a day, from day to day, and from week to week, has been determined. Effort-dependent tests as vital capacity and peak expiratory flow showed the least variability. The greatest variability was seen in effort-independent tests of function such as the maximal expiratory flow rate at 25 per cent (75 per cent of expired vital capacity) and 50 per cent of vital capacity, as well as closing volume. The degree of variability in the tests used was uninfluenced by the periodicity of the tests or the age or smoking habits of the subjects tested. It is suggested that variability of tests of respiratory function should be taken into account in their interpretation.

Adolescent↗