PubMed Health⌕ Search

Biomedical subjects

W Künzel

Publications and source records attributed to W Künzel.

At least 181 records · Page 10Linked to original sources
PubMed1987

Redistribution of fetal circulation during repeated asphyxia in sheep: effects on skin blood flow, transcutaneous PO2, and plasma catecholamines.

To improve the understanding of fetal responses to labour, we have ascertained whether reduced fetal skin blood flow after asphyxia reflects redistribution of the circulation, and if so, whether this can be detected by transcutaneous PO2 monitoring. We also studied the relation between plasma concentrations of catecholamines and organ blood flow. Eight experiments were conducted on 8 acutely-prepared fetal sheep in utero between 125 and 135 days of gestation. In each fetus 11 episodes of asphyxia were induced within 33 min by intermittent arrest of uterine blood flow for 90 s. The distribution of blood flow was measured before and after asphyxia (at 35.5 min) by the isotope-labelled microsphere method. Blood samples were drawn at 0, 33 (i.e. after 90 s recovery), and 40 min to determine blood gases, acid-base balance, and catecholamine concentrations. Fetal transcutaneous PO2, heart rate, arterial blood pressure, and arterial O2 saturation were recorded continuously. Repeated fetal asphyxia increased plasma catecholamine concentrations and caused a circulatory redistribution to the brain (181% change), adrenals (116% change), and lungs (105% change) at the expense of many peripheral organs, particularly of the skin (-61% change). The pattern of these changes was different from that observed by others in persistent hypoxia or asphyxia. The decrease in skin blood flow, which depressed transcutaneous PO2 and increased the arterial-transcutaneous PO2 difference, correlated with the decrease in blood flow to other peripheral organs and with an increase in blood flow to the brain stem. We conclude that reduced blood flow to the fetal skin after repeated episodes of asphyxia indicates circulatory redistribution, which can be detected by transcutaneous PO2 measurements. We suggest that monitoring of variables that depend on skin blood flow may improve fetal surveillance during complicated labour.

Animals↗
PubMed1987

Fetal sympathetic activity, transcutaneous PO2, and skin blood flow during repeated asphyxia in sheep.

To improve detection of fetal distress, we examined whether increased fetal sympathetic activity during repeated episodes of asphyxia decreases skin blood flow, which can be monitored by recording transcutaneous PO2. Sympathetic activity was assessed by relating catecholamine concentrations in the fetal plasma to blood gas, acid-base, and heart rate variables which are commonly used to determine fetal distress. Fifteen experiments were conducted on 8 anaesthetised fetal sheep in utero between 125 and 145 days of gestation (term is at 147 days). They were subjected to 11 consecutive episodes of asphyxia of 30 (n = 3), 60 (n = 9), or 90 (n = 3) s over 33 min, achieved by arrest of uterine blood flow. Blood samples were drawn at 0, 33, and 60 min to determine arterial blood gases, acid base-balance, and concentrations of lactate, glucose, norepinephrine, and epinephrine. Fetal transcutaneous PO2, relative local skin blood flow, heart rate, arterial blood pressure, and arterial O2 saturation were recorded continuously. Fetal plasma concentrations of norepinephrine and epinephrine increased logarithmically as the duration of repeated asphyxia, anaerobic metabolism, and glucose concentrations increased, and as the mean O2 saturation, transcutaneous PO2, and local skin blood flow decreased. We conclude that during repeated episodes of asphyxia in fetal sheep near term, a significant increase in sympathetic activity can be detected indirectly by transcutaneous PO2 monitoring, because sympathetic activation reduces skin blood flow.

Animals↗
PubMed1985

Haemodynamic effects of fenoterol for labour inhibition during spinal or epidural anaesthesia.

Haemodynamic investigations, partly using invasive monitoring, concerning interactions between the beta-mimetic effect of fenoterol and the alpha-sympathetic blockade of spinal or epidural anaesthesia were made in a total of 49 patients during pregnancy, during caesarean section and in non-pregnant women. Haemodynamic effects of fenoterol during regional anaesthesia were compared with those during general anaesthesia (n = 17). Epidural or spinal anaesthesia enhance vascular beta-mimetic reactions at the start of tocolysis, leading to a profound but short-lasting decrease in blood pressure. This initial hypotension is more pronounced after regional than after general anaesthesia.

Adult↗