Meconium and amniotic fluid embolism: effects on coagulation in pregnant mini-pigs.

OBJECTIVE: A hallmark of amniotic fluid embolism is the induction of coagulation defects. Little is known about the nature of these defects or the causative agent or agents. The purpose of this study was to assess the effects of meconium containing (native) meconium-amniotic-fluid infusion (MAFI) and meconium-free (centrifuged) amniotic-fluid infusion (AFI) on the coagulation system in the mini-pig model. DESIGN: Laboratory study. SETTING: University institute animal laboratory. SUBJECTS: Near-term pregnant Göttingen bred mini-pigs in three groups (control, MAFI, AFI) of six animals each. INTERVENTIONS: After induction of anesthesia, amniotic fluid was collected by cesarean section in all animals. Depending on the group, animals received either Ringer's solution (control), native amniotic fluid (MAFI), or centrifuged amniotic fluid (AFI) via an ear vein. MEASUREMENTS AND MAIN RESULTS: Blood samples were taken from a central vein before infusion (baseline), immediately after infusion, every 10 mins until 90 mins after infusion, and finally, every 20 mins until 150 mins after infusion. The following parameters were measured: Platelets, partial thromboplastin time, prothrombin time, fibrinogen, factors V, VII, VIII, antithrombin III, and protein C. The values relative to baseline in the MAFI and AFI groups were compared with control by rank order test. A p<.05 was considered statistically significant. Compared with the control group, platelets were lower in the MAFI group (p<.005), PTT was prolonged in both the MAFI and AFI groups (p<.005), fibrinogen was lower in both the MAFI and AFI groups (p<.05), prothrombin index was lower (i.e., prothrombin time was prolonged) in the MAFI group (p<.05), and protein C was lower in the MAFI group (p<.005). CONCLUSIONS: Both MAFI and, to a much lesser extent, AFI cause an activation of coagulation in mini-pigs. The changes induced by meconium-free AFI are probably not sufficient to explain the high mortality of the condition.

[Stress free anesthesia induction ZESTRANI (ZEro STRess ANesthesia Induction) in Göttingen minipigs. An experimental method]. / Stressfreie Narkoseeinleitung ZESTRANI (ZEro-STRess-ANaesthesia-Induction) beim Göttinger Miniaturschwein. Eine experimentelle Methode.

The Göttingen Mini-pig is a popular laboratory animal, that is used i.a. in experimental surgery and anaesthesia. For ethical and scientific reasons it is mandatory to minimize the stress the laboratory animals are exposed to. The presented stress-free experimental anaesthesia induction (ZESTRANI) is based on innovative means to achieve adequate analgesia using different substances appropriate for the animal's state of consciousness. Markedly lower heart rates and mean arterial pressures are seen when the ZESTRANI-method is used as compared retrospectively to the previously used "conventional" anaesthesia induction. With the ZESTRANI method no "fight or flight"-reactions are seen.

Oximetry for amniotic fluid embolism detection in mini-pigs: tail or snout?

The continuous, non-invasive real-time monitoring of arterial oxygenation (pulse oximetry) has become a standard of care in both human and veterinary medicine. It allows reliable, simple and inexpensive assessment of the arterial oxygenation status. In pigs, commonly used sites for oximetry-probe placement are the ear, snout or tongue, while more recently the 'pig-tail oximetry' has been suggested. In a study regarding the coagulation system during amniotic fluid embolism (AFE) in mini-pigs, we compared tail and snout for oximetry-probe placement and compared them with the 'gold standard': blood-gas analysis (BGA). In both the AFE group and the control group, the tail measurements were slightly lower and the snout measurements were slightly higher than the BGA results. In the experimental model used, both tail and snout measurements were able to detect a temporary desaturation immediately after amniotic fluid embolism (AFE). Blood-gas analysis (BGA) performed on blood drawn from a large artery missed the event. Clinically, there is no significant difference between snout and tail as oximetry-probe placement sites: both are reliable oximetry sites in mini-pigs.