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Biomedical subjects

T Gourlay

Publications and source records attributed to T Gourlay.

9 recordsLinked to original sources

Oedema, Starling and pulse reverse osmosis: towards a possible biochemical marker for oedema.

Several conflicting theories have been proposed to explain the development of oedema. Pulse reverse osmosis (PRO) suggests that oedema occurs when the mean pulse capillary pressure exceeds the osmotic gradient between the plasma and the interstitial fluid. In order to test this concept mean arterial blood pressures and colloid osmotic pressures were taken in a group of healthy volunteers, a group of patients with bilateral ankle oedema and a group of treated hypertensives. Patients with oedema were found to have colloid osmotic pressures (COP's) which were significantly less than those of the healthy volunteers (p <0.001) and the treated hypertensives (p <0.001). The results support the oedema mechanism proposed by PRO and indicate that the relationship between blood pressure and COP may be a useful biochemical marker of oedema and its treatment. Further study is required to numerically quantify this relationship.

Analysis of Variance

The therapeutic significance of pulse reverse osmosis.

Pulse reverse osmosis (1) is a new theory of fluid balance and exchange which suggests that the mean blood pressure and osmotic gradient control fluid balance and that the pulse controls fluid exchange. In vitro testing has confirmed some of the physico chemical principles underlying the theory (2). The hypothesis suggests a relationship between mean capillary blood pressure and osmotic gradient. Imbalance in this relationship can be related to the development of hypertension, hypotension, oedema and shock. In an attempt to test this concept mean blood pressures and colloid osmotic pressures were measured and compared in a group of 50 healthy human volunteers. The results suggest a curvilinear correlation between the mean blood pressure and the COP.

Blood Pressure

Laboratory evaluation of the Pall LG6 leukocyte depleting arterial line filter.

The Pall LG6 arterial line filter has been designed to remove free circulating leukocytes from the arterial line of the extracorporeal circuit employed in openheart surgery. The filter was evaluated and compared to a control filter (Pall Stat-Prime) in terms of its general blood handling characteristics, particularly with regard to the associated level of leukocyte removal. The gross air handling characteristics of the filters were also assessed together with pressure drop. It was found that the filters differed little in terms of all factors studied other than the level of leukocyte depletion. The LG6 filter was associated with substantial levels of leukocyte depletion, particularly the depletion of neutrophils. Over the 90 minute perfusion period the LG6 filter was found to be associated with a neutrophil depletion rate of around 70% while preferentially sparing lymphocytes. This compared to a 10-20% depletion rate in the control filter. This was achieved without apparently compromising the performance of the filter in terms of the other factors studied.

Animals

The effects of pulsatile flow on the leukocyte depleting qualities of the Pall LG6 leukocyte depleting arterial line filter: a laboratory investigation.

The Pall LG6 arterial line filter has, in a previous publication, demonstrated its inherent leukocyte depleting qualities. This initial study was however carried out under continuous flow conditions. The present study was designed to assess the effectiveness of the LG6 filter in performing this leukocyte removal function under the more dynamic conditions of pulsatile flow. In addition to leukocyte depletion, the general blood handling and degree of energy absorption associated with the LG6 and Stat-Prime filters was also assessed. The results demonstrated that the LG6 filter was unaffected by the flow regime employed in terms of leukocyte removal and platelet depletion. There was a higher level of measured haemolysis associated with the use of pulsatile rather than nonpulsatile flow, however, this was the case with both filter types and was not found to be the case when generated values were computed. The LG6 filter absorbed more energy than the Stat-Prime filter as reflected by energy equivalent pressure (EEP) measurement, but this difference did not reach a level which was considered to be clinically significant.

Animals