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Biomedical subjects

G Rooth

Publications and source records attributed to G Rooth.

At least 37 records · Page 2Linked to original sources
PubMed1981

Early reduction of vascular reactivity in diabetic children detected by transcutaneous oxygen electrode.

Reactive hyperaemia in the skin was monitored by transcutaneous measurement of PO2 (tcPO2) (using electrode temperatures of 35 and 37 degrees C) in 13 well controlled diabetic children without clinical signs of vascular disease, and in healthy peers matched for age and sex. The tcPO2 increase was smaller in 12 of the 13 diabetic children than in individual controls. Taking the lower limit of the 95% confidence interval of the increases for the healthy children as a cut-off point, only 4 of the 13 diabetic children had values overlapping into the range of non-diabetics at 37 degrees C. This non-invasive technique, demonstrating a reduced postischaemic response in a group of well controlled diabetic children, may become a useful method for the early detection of diabetic microvascular disorders.

Adolescent↗
PubMed1981

Postischaemic hyperaemia studied with a transcutaneous oxygen electrode used at 33-37 degrees C.

The hyperaemic response in the vasculature of the forearm skin following induced ischaemia was studied with a transcutaneous oxygen (tcpO2) electrode. Electrode temperatures of 35-37 degree C allowed optimal recordings of the postischaemic reaction. During arterial occlusion there was a fall in tcpO2 to zero in 1-3 min. Re-establishment of circulation resulted in a biphasic reaction, with a steep rise overshooting the baseline recording by 1-3 kPa and a slower return to baseline level. At higher electrode temperatures (greater than 39 degree C) there was no overshoot due to hyperaemia. The postischaemic peak response was well reproducible from one occasion to another in the same subject. Simultaneous recording of energy consumption for the heating of the electrode permitted detection of artifacts and environmental changes unrelated to postischaemic hyperaemia, therefore validating the tcpO2 recordings but only at electrode temperatures greater than 35 degree C. The tcpO2 technique used at 35-37 degree C easily detects relative blood flow changes and seems suitable for comparative studies. The method is non-invasive and permits continuous recordings in well-defined skin areas in human subject; significant advantages compared with other methods available.

Adolescent↗
PubMed1980

The effects of mechanical pressure and local stasis on transcutaneous monitoring of fetal oxygen tension.

A methodological study of the influence of local stasis and mechanical pressure on the continuous transcutaneous oxygen tension electrode (tcPO2 electrode) during intrapartum monitoring is presented. No effect of mechanical pressure up to 7.3 kPa (55 mm Hg) on the electrode membrane was found. Reduced blood flow in the capillaries of the tissue beneath the electrode caused by stasis or pressure effect resulted, below a certain threshold value, in tcPO2 decrease. The results emphasize that an attempt to differentiate between a methodologically caused decrease and a decrease due to impaired oxygenation must be made when evaluating the absolute fetal arterial oxygen tension from fetal tcPO2. The consistently observed decrease in relative local perfusion ('flow') may be a help in this respect.

Adult↗
PubMed1979

Time factor in oxygen transfer from mother to fetus.

The time factor in the oxygen transfer from mother to fetus was studied by the tcPO2 technique. When a fairly constant fetal circulation made estimation possible, the decrease in fetal tcPO2 synchronous with and due to the uterine contractions in more than 400 events was always delayed 50--60 sec. Since the time lag in the increase in fetal tcPO2 following administration of pure oxygen to the mother was found to be of the same order of magnitude, the placental part of the delay in the oxygen transfer from mother to fetus can be assumed to be 50--60 sec. This determination supports the prevalent hypothesis that type II dips or late decelerations in the fetal heart rate are caused by hypoxia while type I dips or early decelerations are initiated by other factors.

Female↗
PubMed1979

Integrated interpretation of fetal heart rate, intrauterine pressure and fetal transcutaneous PO2.

By a study of the patterns of changes and the temporal relationship in fetal heart rate, intrauterine pressure, fetal tcPO2 and 'flow', a series of ten typical examples of combined patterns are described. Fetal tcPO2 is affected by the level of the fetal oxygenation and by the blood flow beneath the electrode. Should the latter be below a certain critical level fetal tcPO2 will be lower than fetal scalp blood PO2. By the integrated analysis of the four simultaneously recorded variables the different factors dominating fetal tcPO2 may be identified.

Female↗
PubMed1979

Interpretation of the tcPO2 curve in adult patients in an intensive care unit.

From the data collected on 135 adult patients in an intensive care unit the following conclusions of the interpretation of the transcutaneous PO2 curve in this type of patient may be drawn: 1) One to four minutes after the electrode was attached a nadir (= the lowest initial point) was reached and then there was a gradual increase which ended with an initial plateau. This plateau could be predicted from the lowest initial point by adding 30 mm Hg. 2) If the lowest initial point was 35 mm Hg or less, it was expected that the final tcPO2 level would be lower than the actual PaO2. 3) No correlation was seen between the lowest initial point of the tcPO2 curve and the time until the initial plateau was reached. In 75% of the cases the plateau was reached within 20 minutes. 4) A slight positive correlation was found between arterial blood pressure and lowest initial point. The difference between the means of the lowest initial point for a group with blood pressure less than or equal to 90 mm Hg and another group with blood pressure greater than 120 mm Hg was highly significant. 5) Transcutaneous PO2 measurements were more likely to represent the arterial PO2 level if blood pressure was greater than 120 mm Hg than if it was less than or equal to 90 mm Hg. 6) The lower the initial tcPO2 level, the more likely it was that the arterial level was higher than the tcPO2 level (see also point 2). 7) The differences between PaO2 and tcPO2 were independent of the arterial PO2 level. 8) The overall correlation between PaO2 and tcPO2 in this material was 0.91; the slope was 0.90 and the intercept -8 mm Hg. The correlation coefficient within each individual patient was higher. 9) The correlation coefficient between PaO2 and tcPO2 for those patients in whom PaO2 was 60 mm Hg or less was comparatively low. This may be explained by the bad condition of these patients followed by a reduced blood flow. 10) An initial drop in tcPO2 to zero level indicates a reduced peripheral circulation, but this must be suspected when the initial drop is below 35 mm Hg.

Adolescent↗
PubMed1978

Effect of respiratory physiotherapy on arterial oxygen tension.

The effect of deep breathing on arterial oxygen tension was investigated in 45 postoperative patients. Arterial oxygen tension was estimated by the transcutaneous oxygen tension method, which allows continuous non-invasive measurement of the arterial oxygen tension changes. Three deep breaths in 1 min, assisted by three respiratory therapy devices, were compared to a standard physiotherapy programme. A peak increase in arterial oxygen tension of 3--4.5 mmHg occurred after 1 min, and significantly increased values were seen for 2--4 min following deep breathing with the three respiratory devices. From the various physiotherapeutic procedures, verbally and manually assisted deep breathing gave a 7 mmHg PO2 peak and significantly increased values for 6 min. The sign mechanism is discussed in the light of the present knowledge of airway closure, which gives a satisfactory explanation of the short-lasting increase in oxygen tension.

Closing Volume↗