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Biomedical subjects

F M MacLennan

Publications and source records attributed to F M MacLennan.

14 recordsLinked to original sources
PubMed2002

Saliva cyclic GMP increases during anaesthesia.

BACKGROUND: Cyclic GMP (cGMP) has been implicated in modulating the effects of general anaesthesia. Changes in cGMP in humans undergoing anaesthesia have not been reported previously. METHODS: In this pilot study we measured cGMP in the saliva of six healthy volunteers and eight patients undergoing general anaesthesia for minor gynaecological procedures. Samples were obtained using a commercially available sampling device and cGMP was determined with an enzyme immunoassay and results expressed as a cGMP per mg protein. RESULTS: There was no statistically significant variation in salivary cGMP either day-to-day or between time points in healthy volunteers. Analysis of variance of salivary cGMP of patients undergoing general anaesthesia showed that cGMP increased significantly intraoperatively and returned to preoperative levels after surgery (P=0.03). CONCLUSIONS: This is the first time that real time in vivo changes in salivary cGMP levels during general anaesthesia in humans have been demonstrated and may allow an alternative technique for measuring depth of anaesthesia in the future.

Adult↗
PubMed1999

Fluid management in pre-eclampsia.

We review the evidence base for fluid management in pre-eclampsia. Current understanding of the relevant pathophysiology and the possible impact of styles of fluid management on maternal and fetal outcome are presented. There is little evidence upon which to base the management of fluid balance in pre-eclampsia. Reports are conflicting and no large prospective outcome studies of fluid management have been performed. Volume expansion does not appear to reduce the incidence of fetal distress. Pulmonary oedema and oliguria receive particular attention. There is no evidence of long-term renal damage in pre-eclampsia, but there are strong suggestions that pulmonary oedema is linked to fluid administration. Monitoring is discussed and some principles of management are suggested

Journal Article↗
PubMed1996

An investigation of the changes in aortic diameter and an evaluation of their effect on Doppler measurement of cardiac output in pregnancy.

Measurement of cardiac output by means of Doppler ultrasound is based on the velocity of aortic blood flow and therefore requires that aortic diameter should not change between measurements. Work has been published which suggests that, in pregnancy, aortic diameter varies significantly with systemic blood pressure. The implication of this is that aortic diameter must be remeasured for each determination of cardiac output in pregnant patients. This study investigated the changes in aortic diameter with blood pressure in patients having spinal anaesthesia for caesarean section. Aortic diameter did appear to vary with blood pressure but this variation was within the error of the measurement and did not significantly affect the accuracy of the technique.

Journal Article↗
PubMed1987

Lung water during the puerperium.

An alteration in pulmonary water balance might be expected during pregnancy and the puerperium, as a result of the physiological adaptations to pregnancy. A preliminary investigation of this hypothesis was conducted using a radiological method of lung water measurement in 20 normal primigravidae during the early puerperium. Evidence of interstitial lung water was found in seven of the 20 mothers. There was a significant correlation with plasma volume (p less than 0.05) and fluid turnover (p less than 0.05) in the group with excess lung water. The implications of increased interstitial lung water and its possible causes during pregnancy are discussed.

Adult↗
PubMed1986

Maternal mortality from Mendelson's syndrome: an explanation?

There have been major changes in obstetric and anaesthetic practice since 1946, including the introduction of intravenous infusions, oxytocics, tocolytic drugs, and endotracheal intubation. Some of these may adversely affect pulmonary water balance, which is probably already altered by pregnancy. These changes may have contributed to the increased severity of Mendelson's syndrome in pregnancy and to some extent explain the failure of prophylaxis to reduce maternal deaths.

Anesthesia, Obstetrical↗
PubMed1986

Measurement of total lung water from nuclear magnetic resonance images.

An accurate, non-invasive means of measuring pulmonary water is desirable, for both clinical and research use. Nuclear magnetic resonance imaging is theoretically very suitable for this purpose. Nuclear magnetic resonance (NMR) spectroscopy was used to show that the water content of lung tissue could be predicted accurately from the intensity of signal resulting from a 90 degree saturation recovery sequence. The water contained in an image section may, therefore, be calculated by reference to a 100% water standard. Lung water was obtained by imaging the lung in continuous sections and summing the water contents of the component sections. The method performed well when applied to a sponge phantom, but underestimated by up to 30% in excised sheep lung. The total (vascular and extravascular) pulmonary water measured by NMR in six healthy volunteers was 292 g (SD 58 g) or 4.6 g/kg body weight, less than predicted by some other indirect methods and post-mortem values. A briefer examination comprising two axial sections at standardised levels was also devised. In 15 healthy volunteers the mean water content of a 1.6 cm-thick axial section through the right lung was 17.8 g at the sternal angle, and 23.3 g 5 cm caudally. In the left lung, the values were 16.4 g and 16.3 g, respectively.

Adult↗
PubMed1983

Gammahydroxybutyrate.

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Audiometry, Evoked Response↗