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M Siegemund

Publications and source records attributed to M Siegemund.

13 recordsLinked to original sources
PubMed2006

Effects of dopexamine in a rat model of supracoeliac aortic cross-clamping and declamping.

This experimental study in rats was designed to demonstrate effects of dopexamine (3 microg kg(-1) min(-1), n = 6) or physiologic saline solution (n = 6) on systemic as well as regional perfusion during 30 min of supracoeliac aortic cross-clamping and during 180 min of reperfusion following declamping. Rats were surgically instrumented with arterial, right atrial and portal venous catheters, ultrasonic flow probes around the abdominal aorta, superior mesenteric and carotid artery, and a paediatric tonometer for intestinal mucosal PCO(2) measurement. During 120 min of reperfusion, fluid resuscitation was titrated to keep abdominal aortic blood flow above 80% of baseline values. We found that during cross-clamping, values of arterial lactate (p = 0.002) and intestinal tonometric PCO(2) (p = 0.018) were higher in the dopexamine group than in the control group.

Animals↗
PubMed2006

Microcirculatory recruitment maneuvers correct tissue CO2 abnormalities in sepsis.

The rises in tissue partial pressure of carbon dioxide have been observed in critically ill patients with shock and sepsis for a long time and have been proposed to be an earlier and more reliable marker of tissue hypoxia than traditional markers. However, the mechanisms leading to those increases, especially in sepsis and endotoxemia, are not well understood. Recent studies provided further data, supporting the idea that the origin of those increases in partial pressure of CO2 in sepsis as being caused by microcirculatory perfusion deficit resulting in mitochondrial depression by time. Previously, we have termed this condition where despite correction of systemic oxygen delivery variables, regional hypoxia and oxygen extraction deficit persist as microcirculatory and mitochondrial distress syndrome (MMDS). Recent findings support the idea that the progression from early to severe sepsis is accompanied or possibly even caused by microcirculatory dysfunction, which leads to mitochondrial dysfunction by time. Therefore early identification of microcirculatory dysfunction and correction with microcirculatory recruitment maneuvers are needed to ensure adequate microcirculatory perfusion and tissue oxygenation. Microcirculatory imaging, such as SDF imaging technique, appears to be a very useful tool for this task and its combination together with other systemic and regional tissue oxygenation measurements may provide more information regarding the tissue oxygenation and will be a very promising tool for microcirculatory researchers and the management of critically ill patients at the bedside.

Animals↗
PubMed2003

Neuropsychiatric thalamocortical dysrhythmia: surgical implications.

Clearly, more clinical experience must be amassed to define in detail the possibilities of this surgical approach in disabling neuropsychiatric disorders. We propose, however, that the evidence for benign and efficient surgical intervention against the neuropsychiatric TCD syndrome is already compelling. The potential appearance of strong postoperative reactive manifestations requires a close association between surgery and psychotherapy, with the latter providing support for the integration of the new situation as well as the resolution of old unresolved issues.

Adult↗
PubMed2002

[Obstetric analgesia and anesthesia in Switzerland in 1999].

QUESTION: This survey investigated the common practice of obstetric analgesia and anaesthesia in Swiss hospitals and evaluated the influence of the Swiss interest group for obstetric anaesthesia. METHODS: In March 1999 we submitted 145 questionnaires to all Swiss hospitals providing an obstetric service. RESULTS: The rate of epidural analgesia (EA) was higher in large hospitals (> 1,000 births/year) than in small services. EA was maintained by continuous infusion techniques in 53% of the responding hospitals. For elective caesarean section, spinal anaesthesia (SA) and EA were performed in 77% and 16% of the patients, respectively. General anaesthesia (5%) was only used in small hospitals (< 500 births/year). Emergency caesarean section was performed under SA in 75% of all hospitals and only in 25% was a general anaesthesia used. An already existing EA for labour analgesia was continued for anaesthesia for caesarean section in 63% of Swiss hospitals. CONCLUSIONS: Regional anaesthesia was most commonly used for obstetric anaesthesia in Swiss hospitals. Epidemiological studies, recommendations of the Swiss interest group for obstetric anaesthesia, as well as the expectations of pregnant women, increased the numbers of regional anaesthesia compared with the first survey in 1992.

Adult↗
PubMed2001

The effect of the transfusion of stored RBCs on intestinal microvascular oxygenation in the rat.

BACKGROUND: Although it is known that the transfusion of stored RBCs does not always improve tissue O(2) consumption under conditions of limited tissue oxygenation, the efficiency of O(2) delivery to the microcirculation by stored RBCs has never been determined. STUDY DESIGN AND METHODS: In a rat hemorrhagic shock model, the effects of resuscitation with fresh or 28-day-old RBCs stored in CPD plasma, saline-adenine-glucose-mannitol, and CPDA-1 plasma were investigated. Systemic hemodynamic and intestinal oxygenation measures were monitored. Intestinal microvascular PO(2) was determined with the O(2)-dependent quenching of palladium-porphyrin phosphorescence, and the RBC deformability was measured with a Laser-assisted optic rotational cell analyzer. RESULTS: Hemodynamic and oxygenation measures were significantly decreased during hemorrhagic shock. Intestinal oxygen consumption and mesenteric venous pO(2) were restored with the transfusion of both fresh and stored RBCs, except for CPD-stored RBCs. The intestinal microvascular pO(2) improved only with the transfusion of fresh RBCs. Deformability of the stored RBCs was significantly decreased. CONCLUSION: In contrast to that of fresh RBCs, the transfusion of stored RBCs did not restore the microcirculatory oxygenation, possibly because of impaired O(2) unloading, but, except for CPD-stored RBCs, the storage-induced changes were not enough to impair intestinal VO(2) and mesenteric venous pO(2).

Animals↗
PubMed2001

Critical hematocrit in intestinal tissue oxygenation during severe normovolemic hemodilution.

BACKGROUND: A critical point in oxygen supply for microvascular oxygenation during normovolemic hemodilution has not been identified. The relation between organ microvascular oxygen partial pressure (microPO2) and organ oxygen consumption (VO2) during a decreasing oxygen delivery (DO2) is not well understood. The present study was designed to determine the systemic hematocrit and organ DO2 values below which organ microPO2 and VO2 cannot be preserved by regulatory mechanisms during normovolemic hemodilution. METHODS: Eighteen male Wistar rats were randomized between an experimental group (n = 12), in which normovolemic hemodilution was performed with pasteurized protein solution (PPS), and a control group (n = 6). Systemic hemodynamic and intestinal oxygenation parameters were monitored. Intestinal microPO2 was measured using the oxygen-dependent quenching of palladium-porphyrin phosphorescence. RESULTS: Baseline values in hemodilution and control group were similar. Hemodilution decreased hematocrit to 6.2 +/- 0.8% (mean +/- SD). Constant central venous pressure measurements suggested maintenance of isovolemia. Despite an increasing mesenteric blood flow, intestinal DO2 decreased immediately. Initially, microPO2 was preserved, whereas mesenteric venous PO2 (P(mv)O2) decreased; below a hematocrit of 15%, microPO2 decreased significantly below P(mv)O2. Critical DO2 was 1.5 +/- 0.5 ml x kg(-1) x min(-1) for VO2, and 1.6 +/- 0.5 ml x kg(-1) x min(-1) for microPO2. Critical hematocrit values for VO2 and microPO2 were 15.8 +/- 4.6% and 16.0 +/- 3.5%, respectively. CONCLUSIONS: Intestinal microPO2 and VO2 were limited by a critical decrease in DO2 and hematocrit at the same time. Beyond these critical points not only shunting of oxygen from the microcirculation could be demonstrated, but also a significant correlation between intestinal microPO2 and VO2.

Analysis of Variance↗
PubMed2000

Preservation of intestinal microvascular Po2 during normovolemic hemodilution in a rat model.

The effect of hemodilution on the intestinal microcirculatory oxygenation is not clear. The aim of this study was to determine the effect of moderate normovolemic hemodilution on intestinal microvascular partial oxygen pressure (Po2) and its relation to the mesenteric venous Po2 (Pmvo2). Normovolemic hemodilution was performed in 13 anesthetized male Wistar rats. Systemic hemodynamic and intestinal oxygenation parameters were monitored. Intestinal microvascular Po2 was measured by using the oxygen-dependent quenching of palladium-porphyrin phosphorescence. Hemodilution decreased systemic hematocrit from 45.0% +/- 0.1% (average +/- SEM) to 24.6% +/- 1.6%. The mesenteric blood flow did not change from baseline values, resulting in a linear decrease in intestinal oxygen delivery (from 2.77 +/- 0.15 to 1.42 +/- 0.11 mLxkg(-1)xmin(-1)). The intestinal oxygen extraction ratio increased significantly from 24% +/- 1% to 42% +/- 4%. Pmvo2 decreased significantly (from 57 +/- 2 to 41 +/- 2 mm Hg), but intestinal oxygen consumption and microvascular Po2 remained unaffected. As a result, the difference between microvascular Po2 and Pmvo2 increased significantly during hemodilution. Intestinal microvascular Po2 and oxygen consumption were well preserved during moderate normovolemic hemodilution. These results might be explained by the notion of others that hemodilution induces recruitment of capillaries, resulting in redistribution of the intestinal blood flow in favor of the microcirculation, which allows a more efficient extraction of oxygen. These findings further indicate that the use of venous Po2 values as indicators of microvascular oxygenation may be misleading.

Animals↗
PubMed1999

Systemic and mesenteric hemodynamics, metabolism, and intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping.

OBJECTIVE: To describe systemic and mesenteric hemodynamics, metabolism, and intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping. DESIGN: Prospective, randomized, experimental study. SETTING: University cardiovascular research laboratory. PARTICIPANTS: Twelve male anesthetized and ventilated Sprague-Dawley rats. INTERVENTION: Supraceliac aortic cross-clamping was performed for 30 minutes, followed by declamping and reperfusion for 180 minutes or sham clamping and sham declamping. MEASUREMENTS AND MAIN RESULTS: Mean arterial blood pressure; abdominal aortic, superior mesenteric, and carotid artery blood flow; intestinal mucosal tonometry; hemoglobin; lactate; and blood gases were measured before and after 30 minutes of aortic cross-clamping and 15, 30, 60, 120, and 180 minutes after declamping during reperfusion. Aortic cross-clamping induced an increase in mean arterial pressure (117+/-20 mm Hg to 147+/-12 mm Hg), an increase in right atrial hemoglobin saturation(66%+/-11% to 81%+/-6%), an increase in lactate levels (1.7+/-0.7 mmol/L to 4.3+/-1.3 mmol/L), and an increase in tonometric PCO2 (49.6+/-5.0 mm Hg to 75.6+/-8.6 mm Hg). Three hours of reperfusion after declamping resulted in significantly decreased mean arterial pressure (38+/-10 mm Hg); decreased aortic (101+/-12 mL/min/kg to 57+/-32 mL/min/kg), mesenteric (19+/-4 to 13+/-6 mL/min/kg), and carotid (12+/-4 mL/min/kg to 5+/-3 mL/min/ kg) blood flows; and elevated lactate levels (4.2+/-2.0 mmol/L). Tonometric PCO2 had normalized to baseline levels (51.9+/-3.8 mm Hg), but PCO2 gap was significantly higher than in sham clamped rats (17.9+/-7.8 mm Hg v. 7.0+/-2.6 mm Hg). CONCLUSIONS: Hemodynamic and metabolic effects of aortic cross-clamping and declamping known from large animal models are reproducible using a rat model. Intestinal tonometry indicated mesenteric ischemia during aortic cross-clamping, which was reversible to preclamp values within 30 minutes of reperfusion after declamping.

Animals↗
PubMed1996

Extradural abscess complicating lumbar extradural anaesthesia and analgesia in an obstetric patient.

A 33-year-old nulliparous woman with severe pre-eclampsia was treated with extradural analgesia to control blood pressure and relieve pain during delivery. Nine hours after extradural catheter insertion a Caesarean section was performed due to uterine inertia. The extradural catheter was kept in place for 88 hours. Ten days following the extradural block she developed an extradural abscess and had to undergo a laminectomy. In a retrospective and, in part, prospective analysis on more than 13,000 extradural blocks, we studied the incidence of this dreaded complication and reviewed the literature on clinical findings, diagnosis and treatment.

Abscess↗
PubMedDate not supplied

Initiating extradural analgesia during labour: comparison of three different bupivacaine concentrations used as the loading dose.

OBJECTIVE: Potential effects of extradural analgesia on the progress of labour and obstetric outcome are still a matter of concern and the focus of ongoing debates. Despite this, little attention is paid to the initiation of extradural labour analgesia. The objective of this prospective, randomized, double-blind trial was to identify the optimal of three concentrations of bupivacaine used as a loading bolus for initiating extradural analgesia during labour. METHODS: Sixty-seven full-term parturients requesting extradural analgesia received either bupivacaine 0.25% (group A), 0.125% (group B) or 0. 0625% (group C). Bupivacaine administration was titrated to achieve a pain score </=1.5 on a 10-cm visual analogue scale (VAS) and was limited to a maximum of 20 ml of the study drug. We recorded the time to achieve a VAS </=1.5, the total amount of local anaesthetic used, sensory level, maternal and foetal as well as neonatal side effects. RESULTS: The probability of obtaining a VAS pain score </=1. 5 was significantly lower in group C. Although mean times to reach a VAS pain score </=1.5 were not statistically different, survival curves show a significantly lower probability for reaching this score. Significantly more parturients in group A developed a motor block >/=1 based on using a modified Bromage scoring scale. There were no differences in incidence of maternal hypotension, ephedrine requirements, foetal heart rate abnormalities, mode of delivery and neonatal outcome. CONCLUSIONS: Of the three concentrations used in this clinical setting, 0.125% was the most suitable concentration of plain bupivacaine to initiate extradural analgesia in labour. Using 0.25% bupivacaine increased the incidence of motor block, whereas for 0.0625% plain bupivacaine the probability to achieve adequate analgesia was unacceptably low.

Analgesia, Obstetrical↗